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Sample records for albumin metal interaction

  1. Interaction of Human Serum Albumin with Metal Protoporphyrins

    Science.gov (United States)

    Hu, Jie; Brancaleon, Lorenzo

    2015-03-01

    Fluorescence spectroscopy is widely used in biotechnology, nanotechnology, and molecular biophysics, since it can provide information on a wide range of molecular processes, e.g. the interactions of solvent molecules with fluorophores, conformational changes, and binding interactions etc. In this study, we present the photophysical properties of the interaction of human serum albumin (HSA) with a series of metal compound of Protoporphyrin IX (PPIX), including ZnPPIX, FePPIX, MgPPIX, MnPPIX and SnPPIX respectively, as well as the free base PPIX. Binding constants were retrieved independently using the Benesi-Hildebrand analysis of the porphyrin emission or absorption spectra and the fluorescence quenching (i.e. Stern-Volmer analysis) and reveal that the two methods yield a difference of approximately one order or magnitude between the two. Fluorescence lifetimes was used to probe whether binding of the porphyrin changes the conformation of the protein or if the interaction places the porphyrin at a location that can prompt resonance energy transfer with the lone Tryptophan residue. In recent years it has been discovered that HSA provides a specific binding site for metal-chelated protoporphyrins in subdomain IA. This has opened a novel field of study over the importance of this site for biomedical applications but it has also created the potential for a series of biotechnological applications of the HSA/protoporphyrin complexes. Our study provides a preliminary investigation of the interaction with metal-chelated protoporphyrins that had not been previously investigated.

  2. Interaction of amphiphilic drugs with human and bovine serum albumins.

    Science.gov (United States)

    Khan, Abbul Bashar; Khan, Javed Masood; Ali, Mohd Sajid; Khan, Rizwan Hasan; Kabir-Ud-Din

    2012-11-01

    To know the interaction of amphiphilic drugs nortriptyline hydrochloride (NOT) and promazine hydrochloride (PMZ) with serum albumins (i.e., human serum albumin (HSA) and bovine serum albumin (BSA)), techniques of UV-visible, fluorescence, and circular dichroism (CD) spectroscopies are used. The binding affinity is more in case of PMZ with both the serum albumins. The quenching rate constant (k(q)) values suggest a static quenching process for all the drug-serum albumin interactions. The UV-visible results show that the change in protein conformation of PMZ-serum albumin interactions are more prominent as compared to NOT-serum albumin interactions. The CD results also explain the conformational changes in the serum albumins on binding with the drugs. The increment in %α-helical structure is slightly more for drug-BSA complexes as compared to drug-HSA complexes. Copyright © 2012 Elsevier B.V. All rights reserved.

  3. Serum Albumin Binding and Esterase Activity: Mechanistic Interactions with Organophosphates

    Directory of Open Access Journals (Sweden)

    Nikolay V. Goncharov

    2017-07-01

    Full Text Available The albumin molecule, in contrast to many other plasma proteins, is not covered with a carbohydrate moiety and can bind and transport various molecules of endogenous and exogenous origin. The enzymatic activity of albumin, the existence of which many scientists perceive skeptically, is much less studied. In toxicology, understanding the mechanistic interactions of organophosphates with albumin is a special problem, and its solution could help in the development of new types of antidotes. In the present work, the history of the issue is briefly examined, then our in silico data on the interaction of human serum albumin with soman, as well as comparative in silico data of human and bovine serum albumin activities in relation to paraoxon, are presented. Information is given on the substrate specificity of albumin and we consider the possibility of its affiliation to certain classes in the nomenclature of enzymes.

  4. Bovine Serum Albumin Metal Complexes for Mimic of SOD

    Indian Academy of Sciences (India)

    consequence, it can be considered as a bio-functional mimic of enzyme SOD and has a promising application prospect in antioxidant drug field. Keywords. Bovine serum albumin; biopolymer metal complexes; superoxide; free radical; scavenging activity. 1. Introduction. Reactive oxygen species (ROS), natural byproducts.

  5. Bovine Serum Albumin Metal Complexes for Mimic of SOD

    Indian Academy of Sciences (India)

    Proteins are well-known for efficiency and selecti- vity that few other natural or artificial molecules can match,24,25 whether in catalysis or molecular recogni- tion. Owing to 35 cysteine residues, human serum albu- min (HSA) is facile to be combined with metal ions. The serum albumin is readily available, non-antigenic.

  6. Albumin-drug interaction and its clinical implication.

    Science.gov (United States)

    Yamasaki, Keishi; Chuang, Victor Tuan Giam; Maruyama, Toru; Otagiri, Masaki

    2013-12-01

    Human serum albumin acts as a reservoir and transport protein for endogenous (e.g. fatty acids or bilirubin) and exogenous compounds (e.g. drugs or nutrients) in the blood. The binding of a drug to albumin is a major determinant of its pharmacokinetic and pharmacodynamic profile. The present review discusses recent findings regarding the nature of drug binding sites, drug-albumin binding in certain diseased states or in the presence of coadministered drugs, and the potential of utilizing albumin-drug interactions in clinical applications. Drug-albumin interactions appear to predominantly occur at one or two specific binding sites. The nature of these drug binding sites has been fundamentally investigated as to location, size, charge, hydrophobicity or changes that can occur under conditions such as the content of the endogenous substances in question. Such findings can be useful tools for the analysis of drug-drug interactions or protein binding in diseased states. A change in protein binding is not always a problem in terms of drug therapy, but it can be used to enhance the efficacy of therapeutic agents or to enhance the accumulation of radiopharmaceuticals to targets for diagnostic purposes. Furthermore, several extracorporeal dialysis procedures using albumin-containing dialysates have proven to be an effective tool for removing endogenous toxins or overdosed drugs from patients. Recent findings related to albumin-drug interactions as described in this review are useful for providing safer and efficient therapies and diagnoses in clinical settings. This article is part of a Special Issue entitled Serum Albumin. Copyright © 2013 Elsevier B.V. All rights reserved.

  7. Interaction of mycotoxin zearalenone with human serum albumin.

    Science.gov (United States)

    Poór, Miklós; Kunsági-Máté, Sándor; Bálint, Mónika; Hetényi, Csaba; Gerner, Zsófia; Lemli, Beáta

    2017-05-01

    Zearalenone (ZEN) is a mycotoxin produced mainly by Fusarium species. Fungal contamination of cereals and plants can result in the formation of ZEN, leading to its presence in different foods, animal feeds, and drinks. Because ZEN is an endocrine disruptor, it causes reproductive disorders in farm animals and hyperoestrogenic syndromes in humans. Despite toxicokinetic properties of ZEN were studied in more species, we have no information regarding the interaction of ZEN with serum albumin. Since albumin commonly plays an important role in the toxicokinetics of different toxins, interaction of ZEN with albumin has of high biological importance. Therefore the interaction of ZEN with human serum albumin (HSA) was investigated using spectroscopic methods, ultrafiltration, and molecular modeling studies. Fluorescence spectroscopic studies demonstrate that ZEN forms complex with HSA. Binding constant (K) of ZEN-HSA complex was quantified with fluorescence quenching technique. The determined binding constant (logK=5.1) reflects the strong interaction of ZEN with albumin suggesting the potential biological importance of ZEN-HSA complex formation. Based on the results of the investigations with site markers as well as docking studies, ZEN occupies a non-conventional binding site on HSA. Considering the above listed observations, we should keep in mind this interaction if we would like to precisely understand the toxicokinetic behavior of ZEN. Copyright © 2017 Elsevier B.V. All rights reserved.

  8. Interaction of Tannin with Bovine Serum Albumin by Fluorescence Spectrometry

    OpenAIRE

    Dong-Il, Kim; Son-Ae, Choe; Kye-Ryong, Sin

    2016-01-01

    Interaction between tannin and bovine serum albumin (BSA) was examined by the fluorescent quenching. The process of elimination between BSA and tannin was the one of a stationary state, and the coupling coefficient was one. The working strength between the tannin and the beef serum was hydrophobic one.

  9. Molecular basis of indomethacin-human serum albumin interaction

    DEFF Research Database (Denmark)

    Trivedi, V D; Vorum, H; Honoré, B

    1999-01-01

    Studies on the strength and extent of binding of the non-steroidal anti-inflammatory drug indomethacin to human serum albumin (HSA) have provided conflicting results. In the present work, the serum-binding of indomethacin was studied in 55 mM sodium phosphate buffer (pH 7.0) at 28 degrees C......, by using a fluorescence quench titration technique. The interaction of indomethacin with human serum albumin has been studied as a function of temperature, ionic strength and pH. The results suggest that electrostatic interaction plays a major role in the binding. The possible role of lysine residues...... in this interaction was studied by modifying exposed and buried lysine residues of HSA with potassium cyanate and studying indomethacin binding with the modified HSA. The data suggest that the interaction takes place via a salt bridge formation between the carboxylate group of indomethacin and a buried lysine residue...

  10. Albumin as marker for susceptibility to metal ions in metal-on-metal hip prosthesis patients.

    Science.gov (United States)

    Facchin, F; Catalani, S; Bianconi, E; Pasquale, D De; Stea, S; Toni, A; Canaider, S; Beraudi, A

    2017-04-01

    Metal-on-metal (MoM) hip prostheses are known to release chromium and cobalt (Co), which negatively affect the health status, leading to prosthesis explant. Albumin (ALB) is the main serum protein-binding divalent transition metals. Its binding capacity can be affected by gene mutations or modification of the protein N-terminal region, giving the ischaemia-modified albumin (IMA). This study evaluated ALB, at gene and protein level, as marker of individual susceptibility to Co in MoM patients, to understand whether it could be responsible for the different management of this ion. Co was measured in whole blood, serum and urine of 40 MoM patients. A mutational screening of ALB was performed to detect links between mutations and metal binding. Finally, serum concentration of total ALB and IMA were measured. Serum total ALB concentration was in the normal range for all patients. None of the subjects presented mutations in the investigated gene. Whole blood, serum and urine Co did not correlate with serum total ALB or IMA, although IMA was above the normal limit in most subjects. The individual susceptibility is very important for patients' health status. Despite the limited results of this study, we provide indications on possible future investigations on the toxicological response to Co.

  11. The role of Glutathione, Cysteine and D-Penicillamine in exchanging Palladium and Vanadium metals from albumin metal complex.

    Science.gov (United States)

    Mukhtiar, Muhammad; Jan, Syed Umer; Ullah, Ihsan; Hussain, Abid; Ullah, Izhar; Gul, Rahman; Ali, Essa; Jabbar, Abdul; Kuthu, Zulfiqar Hussan; Wasim, Muhammad; Khan, Muhammad Farid

    2017-11-01

    Thiol groups are extensively present across biological systems being found in range of small molecules (e.g. Glutathione, Homo-cysteine) and proteins (e.g. albumin, haemo-globin). Albumin is considered to be a major thiol containing protein present in circulating Plasma. Albumin contains a single thiolate group located at cysteine-34(cys-34) at its active site. Albumin also binds a wide variety of metals and metals complexes at various sites around the protein. Usually heavy metals are preferentially attached with the thiol group of albumin. The binding of heavy metals at cys-34 provides a mechanism by which the residence time of potentially toxic species in the body can be increased. In this research we have assessed the oxidative modification of and metal binding capacity of cys-34 with heavy metals Palladium and Vanadium to investigate the ease with which it is possible to effect disulfide-thiol exchange at this sites/or remove a metal bound at this position. Both the metals were treated with albumin and then the albumin metals (Pd and V) complexes were treated with small thoil molecules like Glutathione, Cysteine and D-Penicillamine. Our finding showed that the albumin thiol group retained the metals with itself by forming some strong bonding with the Thiols group, it is concluded from this finding that if by chance both the metals enter the living system; strongly disturb the chemistry and physiological function of this bio-molecule.

  12. Investigation of interactions between dendrimer-coated magnetite nanoparticles and bovine serum albumin

    International Nuclear Information System (INIS)

    Pan Bifeng; Gao Feng; Ao Limei

    2005-01-01

    We investigated the interactions between dendrimer-coated magnetite nanoparticles (MNPs) and the protein serum albumin. The investigation was based on the fluorescence quenching of tryptophan residue of serum albumin after binding with the dendrimer-coated magnetite nanoparticles. The extent of the interactions between bovine serum albumin and dendrimer-coated MNPs strongly depends on their surface groups and pH value

  13. [Study on the interaction of doxycycline with human serum albumin].

    Science.gov (United States)

    Hu, Tao-Ying; Chen, Lin; Liu, Ying

    2014-05-01

    The present study was designed to investigate the interaction of doxycycline (DC) with human serum albumin (HSA) by the inner filter effects, displacement experiments and molecular docking methods, based on classic multi-spectroscopy. With fluorescence quenching method at 298 and 310 K, the binding constants Ka, were determined to be 2. 73 X 10(5) and 0. 74X 10(5) L mol-1, respectively, and there was one binding site between DC and HSA, indicating that the binding of DC to HSA was strong, and the quenching mechanism was a static quenching. The thermodynamic parameters (enthalpy change, AH and enthropy change, delta S) were calculated to be -83. 55 kJ mol-1 and -176. 31 J mol-1 K-1 via the Vant' Hoff equation, which indicated that the interaction of DC with HSA was driven mainly by hydrogen bonding and van der Waals forces. Based on the Föster's theory of non-radiation energy transfer, the specific binding distance between Trp-214 (acceptor) and DC (donor) was 4. 98 nm, which was similar to the result confirmed by molecular docking. Through displacement experiments, sub-domain IIA of HSA was assigned to possess the high-affinity binding site of DC. Three-dimensional fluorescence spectra indicated that the binding of DC to HSA induced the conformation change of HSA and increased the disclosure of some part of hydrophobic regions that had been buried before. The results of FTIR spectroscopy showed that DC bound to HSA led to the slight unfolding of the polypeptide chain of HSA. Furthermore, the binding details between DC and HSA were further confirmed by molecular docking methods, which revealed that DC was bound at sub-domain IIA through multiple interactions, such as hydrophobic effect, polar forces and pi-pi interactions. The experimental results provide theoretical basis and reliable data for the study of the interaction between small drug molecule and human serum albumin

  14. Spectroscopic investigations of pentobarbital interaction with human serum albumin

    Science.gov (United States)

    Darwish, Saqer M.; Abu sharkh, Sawsan E.; Abu Teir, Musa M.; Makharza, Sami A.; Abu-hadid, Mahmoud M.

    2010-01-01

    The interaction between pentobarbital and human serum albumin has been investigated. The basic binding interaction was studied by UV-absorption and fluorescence spectroscopy. From spectral analysis pentobarbital showed a strong ability to quench the intrinsic fluorescence of HSA through a static quenching procedure. The binding constant ( k) is estimated at 1.812 × 10 4 M -1 at 293 K. FT-IR spectroscopy with Fourier self-deconvolution technique was used to determine the protein secondary structure and drug binding mechanisms. The observed spectral changes of HSA-pentobarbital complex indicate a larger intensity decrease in the absorption band of α-helix relative to that of β-sheets. This variation in intensity is related indirectly to the formation of H-bonding in the complex molecules, which accounts for the different intrinsic propensities of α-helix and β-sheets.

  15. 3-hydroxyflavone-bovine serum albumin interaction in Dextran medium

    Directory of Open Access Journals (Sweden)

    Voicescu Mariana

    2015-01-01

    Full Text Available Spectroscopic analysis of a bioactive flavonol, 3-Hydroxyflavone (3-HF, in systems based on Dextran 70 (Dx70 (an important bio-relevant polysacharide and Bovine Serum Albumin (BSA (a carrier protein, have been studied by fluorescence and circular dichroism. Changes produced by different concentrations of Dx70 on the fluorescent characteristics of 3-HF, and on the excited - state intramolecular proton transfer (ESIPT process were studied. The influence of 3-HF binding and of Dx70 on the secondary structure of BSA were investigated by circular dichroism spectroscopy. The influence of temperature (30-80°C range on the intrinsic Tryptophan fluorescence in 3-HF/BSA/Dx70 systems, was investigated. The results are discussed with relevance to 3-HF as a sensitive fluorescence probe for exploring flavone-protein interaction in plasma expander media and also for its biological evaluation.

  16. Interaction of indomethacin with adult human albumin and neonatal serum

    DEFF Research Database (Denmark)

    Honoré, B; Brodersen, R; Robertson, A

    1983-01-01

    The binding of indomethacin to albumin was investigated at 37 degrees C, pH 7.4. The first stoichiometric binding constant is 2.5 X 10(5) M-1. Indomethacin utilizes both the bilirubin and diazepam binding functions equally. The effect on bilirubin binding to albumin is negligible at therapeutic...... indomethacin blood levels. Oleic acid does not affect indomethacin binding until the oleate/albumin molar ratio exceeds 2. A method for measuring the reserve albumin equivalent for binding indomethacin is described. Measurement of this reserve binding equivalent in 33 neonatal serum samples shows...

  17. Study of the interaction of kaempferol with bovine serum albumin

    Science.gov (United States)

    Tian, Jianniao; Liu, Jiaqin; Tian, Xuan; Hu, Zhide; Chen, Xingguo

    2004-03-01

    The binding of kaempferol with bovine serum albumin (BSA) was investigated at three temperatures, 296, 310 and 318 K, by the fluorescence, circular dichroism (CD) and Fourier transform infrared spectroscopy (FT-IR) at pH 7.40. The CD and FT-IR studies indicate that kaempferol binds strongly to BSA. The association constant K was determined by Stern-Volmer equation based on the quenching of the fluorescence BSA in the presence of kaempferol. The thermodynamic parameters were calculated according to the dependence of enthalpy change on the temperature as follows: Δ H0 and Δ S0 possess small negative (-1.694 kJ/mol) and positive values (88.814 J/mol K), respectively. According to the displacement experimental and the thermodynamic results, it is considered that kaempferol binding site II (subdomain III) mainly by hydrophobic interaction. The results studied by FT-IR and CD experiments indicate that the secondary structures of the protein have been changed by the interaction of kaempferol with BSA. The distance between the tryptophan residues in BSA and kaempferol bound to site II was estimated to be 2.78 nm using Foster's equation on the basis of fluorescence energy transfer.

  18. Interactions of human serum albumin with doxorubicin in different media

    Science.gov (United States)

    Gun'ko, Vladimir M.; Turov, Vladimir V.; Krupska, Tetyana V.; Tsapko, Magdalina D.

    2017-02-01

    Interactions of human serum albumin (10 wt% H2O and 0.3 wt% sodium caprylate) with doxorubicin hydrochloride (1 wt%) were studied alone or with addition of HCl (3.6 wt% HCl) using 1H NMR spectroscopy. A model of hydrated HSA/12DOX was calculated using PM7 method with COSMO showing large variations in the binding constant depending on structural features of DOX/HSA complexes. DOX molecules/ions displace bound water from narrow intramolecular voids in HSA that leads to diminution of freezing-melting point depression of strongly bound water (SBW). Structure of weakly bound water (WBW) depends much weaker on the presence of DOX than SBW because a major fraction of DOX is bound to adsorption sites of HSA. Addition of HCl results in strong changes in structure of macromolecules and organization of water in hydration shells of HSA (i.e., mainly SBW) and in the solution (i.e., WBW + non-bound bulk water).

  19. Interactions between imazethapyr and bovine serum albumin: Spectrofluorimetric study

    Energy Technology Data Exchange (ETDEWEB)

    Pacheco, Maria E. [Division Quimica Analitica, Departamento de Quimica, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, La Plata, Buenos Aires (Argentina); Bruzzone, Liliana, E-mail: bruzzone@quimica.unlp.edu.ar [Division Quimica Analitica, Departamento de Quimica, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, La Plata, Buenos Aires (Argentina)

    2012-10-15

    The interaction between imazethapyr (IMA) and bovine serum albumin (BSA) was investigated by fluorescence spectroscopy. The Stern-Volmer quenching constant (K{sub SV}) at three temperatures was evaluated in order to determine the quenching mechanism. The dependence of fluorescence quenching on viscosity was also evaluated for this purpose. The results showed that IMA quenches the fluorescence intensity of BSA through a static quenching process. The values of the binding constant for the formed BSA-IMA complex and the number of binding sites were found to be 1.51 Multiplication-Sign 10{sup 5} M{sup -1} and 0.77, respectively, at room temperature. Based on the calculated thermodynamic parameters, the forces that dominate the binding process are hydrogen bonds and van der Waals forces, and the binding process is spontaneous and exothermic. The quenching of protein fluorescence by iodide ion was used to probe the accessibility of tryptophan residues in BSA and the change in accessibility induced by the presence of IMA. According to the obtained results, the BSA-IMA complex is formed in the site where the Trp-134 is located, causing it to become less exposed to the solvent. - Highlights: Black-Right-Pointing-Pointer Fluorescence spectroscopy helps to understand protein binding mechanisms. Black-Right-Pointing-Pointer Quenching measurements reveal the nature of the binding process involved. Black-Right-Pointing-Pointer Iodine ion can be used to study the change in accessibility of tryptophan residues. Black-Right-Pointing-Pointer Thermodynamic parameters for the binding reaction confirm binding modes.

  20. Interaction of carbon nanoparticles to serum albumin: elucidation of the extent of perturbation of serum albumin conformations and thermodynamical parameters.

    Science.gov (United States)

    Mandal, Samir; Hossain, Maidul; Devi, P Sujatha; Kumar, Gopinatha Suresh; Chaudhuri, Keya

    2013-03-15

    Carbon nanoparticles continuously generated from industries and vehicles due to incomplete combustion of fuels is one of the potent causes of air pollution. The exposure of this polluted air with carbon nanoparticles, introduced into the bloodstream of animals in the course of respiration, motivated us to study their interaction with plasma proteins, bovine serum albumin and human serum albumin. Carbon nanoparticles with very small size and high purity were synthesized by dehydration of d-glucose using concentrated sulphuric acid as dehydrating agent. These were characterized by transmission electron microscopy, atomic force microscopy, X-ray diffraction, Raman spectroscopy, FTIR spectroscopy and UV-visible spectroscopy. Carbon nanoparticles-protein interactions were studied by fluorescence spectroscopy, circular dichroism spectroscopy and isothermal titration calorimetry. The fluorescence quenching constants and thermodynamic parameters such as enthalpy change (ΔH°), entropy change (ΔS°) and free energy change (ΔG°) were calculated, which indicated a strong static quenching and primary electrostatic interaction between the carbon nanoparticles and blood proteins. Circular dichroism spectra provided the information about the secondary structure alteration of the proteins in presence of carbon nanoparticles. These findings have shed light towards an understanding of the interactions between carbon nanoparticles and serum proteins which may clarify the potential risks and undesirable health effects of carbon nanoparticles, as well as the related cellular trafficking and systemic translocation. Copyright © 2013 Elsevier B.V. All rights reserved.

  1. Interaction of norfloxacin with bovine serum albumin studied by different spectrometric methods; displacement studies, molecular modeling and chemometrics approaches

    Energy Technology Data Exchange (ETDEWEB)

    Naseri, Abdolhossein, E-mail: a_naseri@tabrizu.ac.ir [Departments of Analytical Chemistry, Faculty of Chemistry, University of Tabriz, Tabriz 51666-16471 (Iran, Islamic Republic of); Hosseini, Soheila [Departments of Analytical Chemistry, Faculty of Chemistry, University of Tabriz, Tabriz 51666-16471 (Iran, Islamic Republic of); Rasoulzadeh, Farzaneh [Drug Applied Research Center, Tabriz University of Medical Sciences, Tabriz 51644-14766 (Iran, Islamic Republic of); Rashidi, Mohammad-Reza [Research Center for Pharmaceutical Nanotechnology, Tabriz University of Medical Sciences, Tabriz 51644-14766 (Iran, Islamic Republic of); Zakery, Maryam; Khayamian, Taghi [Department of Chemistry, College of Chemistry, Isfahan University of Technology, Isfahan 84154 (Iran, Islamic Republic of)

    2015-01-15

    Serum albumins as major target proteins can bind to other ligands leading to alteration of their pharmacological properties. The mechanism of interaction between norfloxacin (NFLX) with bovine serum albumin (BSA) was investigated. Fuorescence quenching of serum albumin by this drug was found to be a static quenching process. The binding sites number, n, apparent binding constant, K, and thermodynamic parameters were calculated at different temperatures. The distance, r, between donor, BSA, and acceptor, NFLX, was calculated according to the Forster theory of non-radiation energy transfer. Also binding characteristics of NFLX with BSA together with its displacement from its binding site by kanamycin and effect of common metal ions on binding constant were investigated by the spectroscopic methods. The conformational change in the secondary structure of BSA upon interaction with NFLX was investigated qualitatively from synchronous fluorescence spectra, Fourier Transform Infrared (FTIR) and circular dichroism (CD) spectrometric methods. Molecular docking studies were performed to obtain information on the possible residues involved in the interaction process and changes in accessible surface area of the interacting residues. The results showed that the conformation of BSA changed in the presence of NFLX. For the first time, displacement studies were used for this interaction; displacement studies showed that NFLX was displaced by phenylbutazon and ketoprofen but was not displaced by ibuprofen indicating that the binding site of NFLX on albumin was site I. In addition a powerful chemometrics method, multivariate curve resolution-alternating least square, was used for resolution of spectroscopic augmented data obtained in two different titration modes in order to extract spectral information regardless of spectral overlapping of components. - Highlights: • Interaction between norfloxacin and BSA is studied by spectral methods. • Chemometrics methods are used to

  2. Spectroscopic studies on the interaction between chalcone and bovine serum albumin

    Energy Technology Data Exchange (ETDEWEB)

    Naik, Keerti M.; Nandibewoor, Sharanappa T., E-mail: stnandibewoor@yahoo.com

    2013-11-15

    The interaction between chalcone and bovine serum albumin (BSA) has been studied by spectroscopic techniques under physiological condition. By the analysis of fluorescence spectrum and fluorescence intensity, it was observed that the chalcone has a strong ability to quench the intrinsic fluorescence with BSA through a static quenching procedure and non-radiation energy transfer were the main reasons for the fluorescence quenching. The association constants of chalcone with BSA were determined at different temperatures based on fluorescence quenching results. The positive entropy change and enthalpy change indicated that the interaction of chalcone and BSA was driven mainly by hydrophobic forces. The process of binding was a spontaneous process in which Gibbs free energy change was negative. The distance, r, between donor (BSA) and acceptor (chalcone) was obtained according to the Forster's theory of non-radiation energy transfer. The UV–vis, CD, FT-IR, synchronous and 3-D spectral results revealed the changes in the secondary structure of BSA upon interaction with chalcone. The effects of some common metal ions on binding of BSA–chalcone complex were also investigated. -- Highlights: • We explored the interaction between chalcone and BSA by fluorescence spectroscopy. • The fluorescence quenching mechanism was static quenching. • The binding constants and thermodynamic parameters were calculated. • The interaction is driven mainly by hydrophobic force. • The binding of chalcone to BSA induced changes in the secondary structure of BSA.

  3. Metal interactions with boron clusters

    International Nuclear Information System (INIS)

    Grimes, R.N.

    1982-01-01

    This book presents information on the following topics: the structural and bonding features of metallaboranes and metallacarboranes; transition-metal derivatives of nido-boranes and some related species; interactions of metal groups with the octahydrotriborate (1-) anion, B 3 H 8 ; metallaboron cage compounds of the main group metals; closo-carborane-metal complexes containing metal-carbon and metal-boron omega-bonds; electrochemistry of metallaboron cage compounds; and boron clusters with transition metal-hydrogen bonds

  4. Photo-physical and structural interactions between viologen phosphorus-based dendrimers and human serum albumin

    Energy Technology Data Exchange (ETDEWEB)

    Ciepluch, Karol, E-mail: ciepluch@biol.uni.lodz.pl [Department of General Biophysics, University of Lodz, 141/143 Pomorska St., 90-236 Lodz (Poland); Katir, Nadia [Laboratoire de Chimie de Coordination du CNRS (LCC), 205 route de Narbonne, F-31077 Toulouse cedex 4 (France); Institute of Nanomaterials and Nanotechnology (INANOTECH)-MAScIR (Moroccan Foundation for Advanced Science, Innovation and Research), ENSET, Avenue de l' Armee Royale, Madinat El Irfane, 10100 Rabat (Morocco); El Kadib, Abdelkrim [Institute of Nanomaterials and Nanotechnology (INANOTECH)-MAScIR (Moroccan Foundation for Advanced Science, Innovation and Research), ENSET, Avenue de l' Armee Royale, Madinat El Irfane, 10100 Rabat (Morocco); Weber, Monika [Department of General Biophysics, University of Lodz, 141/143 Pomorska St., 90-236 Lodz (Poland); Caminade, Anne-Marie [Laboratoire de Chimie de Coordination du CNRS (LCC), 205 route de Narbonne, F-31077 Toulouse cedex 4 (France); Bousmina, Mostapha [Hassan II Academy of Sciences and Technology, Avenue MVI, Km4, 10220 Rabat (Morocco); Pierre Majoral, Jean [Laboratoire de Chimie de Coordination du CNRS (LCC), 205 route de Narbonne, F-31077 Toulouse cedex 4 (France); Hassan II Academy of Sciences and Technology, Avenue MVI, Km4, 10220 Rabat (Morocco); Bryszewska, Maria [Department of General Biophysics, University of Lodz, 141/143 Pomorska St., 90-236 Lodz (Poland)

    2012-06-15

    This work deals with photo-physical and structural interactions between viologen phosphorus dendrimers and human serum albumin (HSA). Viologens are derivatives of 4,4 Prime -bipyridinium salts. Aiming to rationalize the parameters governing such interactions eight types of these polycationic dendrimers in which the generation, the number of charges, the nature of the core and of the terminal groups vary from one to another, were designed and used. The influence of viologen-based dendrimers' on human serum albumin has been investigated. The photo-physical interactions of the two systems have been monitored by fluorescence quenching of free L-tryptophan and of HSA tryptophan residue. Additionally, using circular dichroism (CD) the effect of dendrimers on the secondary structure of albumin was measured. The obtained results show that viologen dendrimers interact with human serum albumin quenching its fluorescence either by collisional (dynamic) way or by forming complexes in a ground state (static quenching). In some cases the quenching is accompanied by changes of the secondary structure of HSA. - Highlights: Black-Right-Pointing-Pointer Photo-physical interactions between viologen phosphorus dendrimers and human serum albumin (HSA) were investigated. Black-Right-Pointing-Pointer The viologen dendrimers can quench the fluorescence of tryptophan in HSA. Black-Right-Pointing-Pointer CD spectra to explain the changes in secondary structure of albumin after exposition of dendrimers.

  5. The investigation of the interaction between edaravone and bovine serum albumin by spectroscopic approaches

    Energy Technology Data Exchange (ETDEWEB)

    Yu Xianyong; Yang Ying; Liu Ronghua; Huang Haowen; Chen Jian; Ji Danhong [Key Laboratory of Theoretical Chemistry and Molecular Simulation of Ministry of Education, Hunan Province College Key Laboratory of QSAR/QSPR, School of Chemistry and Chemical Engineering, Hunan University of Science and Technology, Xiangtan 411201 (China); Li Xiaofang, E-mail: fine_chem@163.co [Key Laboratory of Theoretical Chemistry and Molecular Simulation of Ministry of Education, Hunan Province College Key Laboratory of QSAR/QSPR, School of Chemistry and Chemical Engineering, Hunan University of Science and Technology, Xiangtan 411201 (China); Yang Fengxian [Key Laboratory of Theoretical Chemistry and Molecular Simulation of Ministry of Education, Hunan Province College Key Laboratory of QSAR/QSPR, School of Chemistry and Chemical Engineering, Hunan University of Science and Technology, Xiangtan 411201 (China); Yi Pinggui, E-mail: pgyi@hnust.c [Key Laboratory of Theoretical Chemistry and Molecular Simulation of Ministry of Education, Hunan Province College Key Laboratory of QSAR/QSPR, School of Chemistry and Chemical Engineering, Hunan University of Science and Technology, Xiangtan 411201 (China)

    2011-07-15

    The fluorescence and ultraviolet spectroscopies were explored to study the interaction between edaravone (EDA) and bovine serum albumin (BSA) under imitated physiological condition. The experimental results show that the fluorescence quenching mechanism between EDA and BSA is a combined quenching (dynamic and static quenching). The binding constants, binding sites, and the corresponding thermodynamic parameters ({Delta}G, {Delta}H, and {Delta}S) of the interaction system were calculated at different temperatures. According to Foerster non-radiation energy transfer theory, the binding distance between EDA and BSA was calculated to be 3.10 nm. The effect of EDA on the conformation of BSA was analyzed using synchronous fluorescence spectroscopy. In addition, the effects of some common metal ions Mg{sup 2+}, Ca{sup 2+}, Cu{sup 2+}, and Ni{sup 2+} on the binding constant between EDA and BSA were examined. - Highlights: {yields} We explored the interaction of BSA and EDA using spectroscopic methods. {yields} The fluorescence quenching mechanism is combined quenching. {yields} Hydrophobic interaction force plays a major role in stabilizing the complex. {yields} The binding constants, binding sites, and thermodynamic parameters were calculated. {yields} EDA affects the conformation of tryptophan residue's microregion.

  6. Spectroscopic analysis of the riboflavin-serum albumins interaction on silver nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Voicescu, Mariana, E-mail: voicescu@icf.ro; Angelescu, Daniel G. [Institute of Physical Chemistry ' Ilie Murgulescu' , Romanian Academy (Romania); Ionescu, Sorana [University of Bucharest, Department of Physical Chemistry (Romania); Teodorescu, Valentin S. [Institute of Atomic Physics, National Institute of Materials Physics (Romania)

    2013-04-15

    Spectrophotometric behavior of riboflavin (RF) adsorbed on silver nanoparticles as well as its interaction with two serum albumins, BSA and HSA, respectively, has been evidenced. The time evolution of the plasmonic features of the complexes formed by RF/BSA/HSA and Ag(0) nanoparticles having an average diameter of 10.0 {+-} 2.0 nm have been investigated by UV-Vis absorption spectroscopy. Using steady-state and time-resolved fluorescence spectroscopy, the structure, stability, and dynamics of the serum albumins have been studied. The efficiency of energy transfer process between RF and serum albumins on silver nanoparticles has been estimated. A reaction mechanism of RF with silver nanoparticles is also proposed and the results are discussed with relevance to the involvement of the silver nanoparticles to the redox process of RF and to the RF-serum albumins interaction into a silver nanoparticles complex.

  7. Spectroscopic analysis of the riboflavin—serum albumins interaction on silver nanoparticles

    Science.gov (United States)

    Voicescu, Mariana; Angelescu, Daniel G.; Ionescu, Sorana; Teodorescu, Valentin S.

    2013-04-01

    Spectrophotometric behavior of riboflavin (RF) adsorbed on silver nanoparticles as well as its interaction with two serum albumins, BSA and HSA, respectively, has been evidenced. The time evolution of the plasmonic features of the complexes formed by RF/BSA/HSA and Ag(0) nanoparticles having an average diameter of 10.0 ± 2.0 nm have been investigated by UV-Vis absorption spectroscopy. Using steady-state and time-resolved fluorescence spectroscopy, the structure, stability, and dynamics of the serum albumins have been studied. The efficiency of energy transfer process between RF and serum albumins on silver nanoparticles has been estimated. A reaction mechanism of RF with silver nanoparticles is also proposed and the results are discussed with relevance to the involvement of the silver nanoparticles to the redox process of RF and to the RF-serum albumins interaction into a silver nanoparticles complex.

  8. Bovine Serum Albumin Metal Complexes for Mimic of SOD

    Indian Academy of Sciences (India)

    Furthermore, the scavenging superoxide anion free radical (O•−₂ ) activity of biopolymer-metal complexes were determined by nitroblue tetrazolium light reduction assay method. The antioxidant capacity of BSA-M has markedly increased. The conjugated BSA-M (M=Cu, Mn) showed preeminent scavenging activity ...

  9. Biomolecular Interaction Study of Cyclolinopeptide A with Human Serum Albumin

    Directory of Open Access Journals (Sweden)

    Ben Rempel

    2010-01-01

    Full Text Available The kinetics, energetics, and structure of Cyclolinopeptide A binding with Human Serum Albumin were investigated with surface plasmon resonance and circular dichroism. The complex is formed through slow recognition kinetics that is temperature sensitive in the range of 20°C–37°C. The overall reaction was observed to be endothermic (ΔH=204 kJ mol−1 and entropy driven (ΔS=746 J mol−1K−1 with overall small changes to the tertiary structure.

  10. Multi-spectroscopic characterization of bovine serum albumin upon interaction with atomoxetine

    Directory of Open Access Journals (Sweden)

    Arunkumar T. Buddanavar

    2017-06-01

    Full Text Available The quenching interaction of atomoxetine (ATX with bovine serum albumin (BSA was studied in vitro under optimal physiological condition (pH=7.4 by multi-spectroscopic techniques. The mechanism of ATX-BSA system was a dynamic quenching process and was confirmed by the fluorescence spectra and lifetime measurements. The number of binding sites, binding constants and other binding characteristics were computed. Thermodynamic parameters ∆H° and ∆S° indicated that intermolecular hydrophobic forces predominantly stabilized the drug-protein system. The average binding distance between BSA and ATX was studied by Försters theory. UV-absorption, Fourier transform infrared spectroscopy (FT-IR, circular dichroism (CD, synchronous spectra and three-dimensional (3D fluorescence spectral results revealed the changes in micro-environment of secondary structure of protein upon the interaction with ATX. Displacement of site probes and the effects of some common metal ions on the binding of ATX with BSA interaction were also studied.

  11. Investigation of the interaction between indigotin and two serum albumins by spectroscopic approaches

    Directory of Open Access Journals (Sweden)

    Zheng-Jun Cheng

    2013-08-01

    Full Text Available The binding characteristics of indigotin with human serum albumin (HSA and bovine serum albumin (BSA have been investigated by various spectroscopic techniques. Spectroscopic analysis revealed that the quenching mechanism between indigotin and HSA/BSA belonged to the static quenching. The displacement experiments suggested that indigotin primarily bound to tryptophan residues on proteins within site I. The thermodynamic parameters indicated that the binding of indigotin–HSA/BSA mainly depended on the hydrophobic interaction. The binding distance of indigotin to HSA/BSA was evaluated. The results by synchronous fluorescence, three-dimensional fluorescence, Fourier Transform Infrared spectroscopy (FT-IR and circular dichroism (CD spectra showed that the conformation of proteins altered in the presence of indigotin. Keywords: Human serum albumin, Bovine serum albumin, Indigotin, Fluorescence spectroscopy, Binding constants

  12. Effects of urea, metal ions and surfactants on the binding of baicalein with bovine serum albumin

    Directory of Open Access Journals (Sweden)

    Atanu Singha Roy

    2016-08-01

    Full Text Available The interaction of baicalein with bovine serum albumin (BSA was investigated with the help of spectroscopic and molecular docking studies. The binding affinity of baicalein towards BSA was estimated to be in order of 105 M−1 from fluorescence quenching studies. Negative ΔH° (−5.66±0.14 kJ/mol and positive (ΔS° (+79.96±0.65 J/mol K indicate the presence of electrostatic interactions along with the hydrophobic forces that result in a positive ΔS°. The hydrophobic association of baicalein with BSA diminishes in the presence of sodium dodecyl sulfate (SDS due to probable hydrophobic association of baicalein with SDS, resulting in a negative ΔS° (−40.65±0.87 J/mol K. Matrix-assisted laser desorption ionization/time of flight (MALDI--TOF experiments indicate a 1:1 complexation between baicalein and BSA. The unfolding and refolding phenomena of BSA were investigated in the absence and presence of baicalein using steady-state and fluorescence lifetime measurements. It was observed that the presence of urea ruptured the non-covalent interaction between baicalein and BSA. The presence of metal ions (Ag+, Mg2+, Ni2+, Mn2+, Co2+and Zn2+ increased the binding affinity of ligand towards BSA. The changes in conformational aspects of BSA after ligand binding were also investigated using circular dichroism (CD and Fourier transform infrared (FT-IR spectroscopic techniques. Site selectivity studies following molecular docking analyses indicated the binding of baicalein to site 1 (subdomain IIA of BSA.

  13. Interaction of Water-Soluble CdTe Quantum Dots with Bovine Serum Albumin

    Science.gov (United States)

    2011-01-01

    Semiconductor nanoparticles (quantum dots) are promising fluorescent markers, but it is very little known about interaction of quantum dots with biological molecules. In this study, interaction of CdTe quantum dots coated with thioglycolic acid (TGA) with bovine serum albumin was investigated. Steady state spectroscopy, atomic force microscopy, electron microscopy and dynamic light scattering methods were used. It was explored how bovine serum albumin affects stability and spectral properties of quantum dots in aqueous media. CdTe–TGA quantum dots in aqueous solution appeared to be not stable and precipitated. Interaction with bovine serum albumin significantly enhanced stability and photoluminescence quantum yield of quantum dots and prevented quantum dots from aggregating. PMID:27502633

  14. Characterizing the Interaction between tartrazine and two serum albumins by a hybrid spectroscopic approach.

    Science.gov (United States)

    Pan, Xingren; Qin, Pengfei; Liu, Rutao; Wang, Jing

    2011-06-22

    Tartrazine is an artificial azo dye commonly used in food products. The present study evaluated the interaction of tartrazine with two serum albumins (SAs), human serum albumin (HSA) and bovine serum albumin (BSA), under physiological conditions by means of fluorescence, three-dimensional fluorescence, UV-vis absorption, and circular dichroism (CD) techniques. The fluorescence data showed that tartrazine could bind to the two SAs to form a complex. The binding process was a spontaneous molecular interaction procedure, in which van der Waals and hydrogen bond interactions played a major role. Additionally, as shown by the UV-vis absorption, three-dimensional fluorescence, and CD results, tartrazine could lead to conformational and some microenvironmental changes of both SAs, which may affect the physiological functions of SAs. The work provides important insight into the mechanism of toxicity of tartrazine in vivo.

  15. Interactions of hemin with bovine serum albumin and human hemoglobin: A fluorescence quenching study

    Science.gov (United States)

    Makarska-Bialokoz, Magdalena

    2018-03-01

    The binding interactions between hemin (Hmi) and bovine serum albumin (BSA) or human hemoglobin (HHb), respectively, have been examined in aqueous solution at pH = 7.4, applying UV-vis absorption, as well as steady-state, synchronous and three-dimensional fluorescence spectra techniques. Representative results received for both BSA and HHb intrinsic fluorescence proceeding from the interactions with hemin suggest the formation of stacking non-covalent and non-fluorescent complexes in both the Hmi-BSA and Hmi-HHb systems, with highly possible concurrent formation of a coordinate bond between a group on the protein surface and the metal in Hmi molecule. All the values of calculated parameters, the binding, fluorescence quenching and bimolecular quenching rate constants point to the involvement of static quenching in both the systems studied. The blue shift in the synchronous fluorescence spectra imply the participation of both tryptophan and tyrosine residues in quenching of BSA and HHb intrinsic fluorescence. Depicted outcomes suggest that hemin is supposedly able to influence the physiological functions of BSA and HHb, the most important blood proteins, particularly in case of its overuse.

  16. Synthesis, characterization and biological application of four novel metal-Schiff base complexes derived from allylamine and their interactions with human serum albumin: Experimental, molecular docking and ONIOM computational study.

    Science.gov (United States)

    Kazemi, Zahra; Rudbari, Hadi Amiri; Sahihi, Mehdi; Mirkhani, Valiollah; Moghadam, Majid; Tangestaninejad, Shahram; Mohammadpoor-Baltork, Iraj; Gharaghani, Sajjad

    2016-09-01

    Novel metal-based drug candidate including VOL2, NiL2, CuL2 and PdL2 have been synthesized from 2-hydroxy-1-allyliminomethyl-naphthalen ligand and have been characterized by means of elemental analysis (CHN), FT-IR and UV-vis spectroscopies. In addition, (1)H and (13)C NMR techniques were employed for characterization of the PdL2 complex. Single-crystal X-ray diffraction technique was utilized to characterise the structure of the complexes. The Cu(II), Ni(II) and Pd(II) complexes show a square planar trans-coordination geometry, while in the VOL2, the vanadium center has a distorted tetragonal pyramidal N2O3 coordination sphere. The HSA-binding was also determined, using fluorescence quenching, UV-vis spectroscopy, and circular dichroism (CD) titration method. The obtained results revealed that the HSA affinity for binding the synthesized compounds follows as PdL2>CuL2>VOL2>NiL2, indicating the effect of metal ion on binding constant. The distance between these compounds and HSA was obtained based on the Förster's theory of non-radiative energy transfer. Furthermore, computational methods including molecular docking and our Own N-layered Integrated molecular Orbital and molecular Mechanics (ONIOM) were carried out to investigate the HSA-binding of the compounds. Molecular docking calculation indicated the existence of hydrogen bond between amino acid residues of HSA and all synthesized compounds. The formation of the hydrogen bond in the HSA-compound systems leads to their stabilization. The ONIOM method was utilized in order to investigate HSA binding of compounds more precisely in which molecular mechanics method (UFF) and semi empirical method (PM6) were selected for the low layer and the high layer, respectively. The results show that the structural parameters of the compounds changed along with binding to HSA, indicating the strong interaction between the compounds and HSA. The value of binding constant depends on the extent of the resultant changes. This

  17. Biological Interaction of Molybdenocene Dichloride with Bovine Serum Albumin Using Fluorescence Spectroscopy

    Science.gov (United States)

    Domínguez, Moralba; Cortes-Figueroa, Jose´ E.; Meléndez, Enrique

    2018-01-01

    Bioinorganic topics are ubiquitous in the inorganic chemistry curriculum; however, experiments to enhance understanding of related topics are scarce. In this proposed laboratory, upper undergraduate students assess the biological interaction of molybdenocene dichloride (Cp2MoCl2) with bovine serum albumin (BSA) by fluorescence spectroscopy.…

  18. Interaction of serum albumins with cyclodextrins: How safe is the use ...

    Indian Academy of Sciences (India)

    Interaction of cyclodextrins with human and bovine serum albumin: A combined spectroscopic and computational investigation. Saptarshi Ghosh, Bijan Kumar Paul, Nitin Chattopadhyay*. Department of Chemistry, Jadavpur University, Kolkata - 700 032, India. *Corresponding author: Fax: 91-33-2414 6584. E-mail: ...

  19. Thermodynamic Study of the Interaction of Bovine Serum Albumin and Amino Acids with Cellulose Nanocrystals

    OpenAIRE

    Lombardo, Salvatore; Eyley, Sam; Schütz, Christina; Van Gorp, Hans; Rosenfeldt, Sabine; Van den Mooter, Guy; Thielemans, Wim

    2017-01-01

    The interaction of bovine serum albumin (BSA) with sulfated, carboxylated, and pyridinium-grafted cellulose nanocrystals (CNCs) was studied as a function of the degree of substitution by determining the adsorption isotherm and by directly measuring the thermodynamics of interaction. The adsorption of BSA onto positively charged pyridinium-grafted cellulose nanocrystals followed Langmuirian adsorption with the maximum amount of adsorbed protein increasing linearly with increasing degree of sub...

  20. Characterization of the interaction between 3-Oxotabersonine and two serum albumins by using spectroscopic techniques

    International Nuclear Information System (INIS)

    Wang, Qing; Yan, Jin; He, Jiawei; Bai, Keke; Li, Hui

    2013-01-01

    3-Oxotabersonine (OTAB) is a component of Voacanga africana, which is a type of traditional drug in Africa widely used for treating diseases. This study examines the interaction of OTAB with bovine serum albumin (BSA) and human serum albumin (HSA) under physiological conditions. The interaction between OTAB and BSA/HSA was investigated using fluorescence spectroscopy, Fourier transform infrared (FT-IR) spectroscopy, circular dichroism (CD) spectroscopy, and molecular modeling under simulated physiological conditions. The experimental results confirm that the quenching mechanism is a static quenching process. The binding site number (n) and the apparent binding constant (K) were measured at various temperatures. The thermodynamic parameters, namely, enthalpy change (ΔH) and entropy change (ΔS), were calculated. Furthermore, the structural changes in the serum albumin that affected the OTAB binding were determined using FT-IR. The binding site was assumed to be located in site I of the BSA/HSA (subdomain IIA). -- Highlights: ► Make use of the 3-Oxotabersonine firstly extracted from seeds of Voacanga africana Stapf to study the drug–protein system. ► Use two kinds of similar structure serum albumins to do a comparative study. ► FT-IR was used to study the conformational change of BSA and HSA. ► Use the BSA and HSA structure obtained from the Brookhaven Protein Data Bank for molecular docking

  1. Interaction of phosphatidylcholine with bovine serum albumin. Specificity and properties of the complexes.

    Science.gov (United States)

    Jonas, A

    1976-03-18

    Phosphatidylcholine dispersed on Celite was rapidly solubilized by neutral bovine serum albumin solutions. Stable protein-lipid complexes were isolated by Agrose gel filtration or by ultracentrifugal flotation in high density solvents, and the physicochemical properties of the complexes were investigated in terms of the stoichiometry of binding, effect of fatty acid ligands on phosphatidylcholine binding, effect of high ionic strength on the stability of the complexes, intrinsic fluorescence and circular dichroism spectra, and sedimentation velocity coefficients. Complexes containing from 2 to 30 phosphatidylcholine molecules per protein molecule were observed; however, no saturation of binding sites could be detected in this range of molar ratios. Oleic acid binding by serum albumin prevents interaction of the protein with phosphatidylcholine, indicating possible competition of these ligands at low contents of the phospholipid. For molar ratios of up to 10 phosphatidylcholine molecules per serum albumin, binding is primarily due to hydrophobic interactions that have no effect on the overall shape and secondary structure of the native protein except for local modifications at tryptophan residues, whose fluorescence becomes quenched and blue shifted on phosphatidylcholine binding. Similar phosphatidylcholine uptake experiments performed with a series of globular proteins indicated that the lipid extraction from Celite surfaces is a non-specific process, accelerated by several other proteins (e.g. aldolase, egg albumin, chymotrypsinogen, soybean trypsin inhibitor, and the major apolipoprotein from bovine serum high density lipoprotein). Formation of stable protein-lipid complexes, however, was only observed with bovine serum albumin, which in contrast to the other proteins is known to have affinity binding sites for anions with hydrophobic side chains.

  2. The role of colloid particles in the albumin-lanthanides interaction: The study of aggregation mechanisms.

    Science.gov (United States)

    Tikhonova, Tatiana N; Shirshin, Evgeny A; Romanchuk, Anna Yu; Fadeev, Victor V

    2016-10-01

    We studied the interaction between bovine serum albumin (BSA) and lanthanide ions in aqueous solution in the 4.0÷9.5pH range. A strong increase of the solution turbidity was observed at pH values exceeding 6, which corresponds to the formation of Ln(OH)3 nanoparticles, while no changes were observed near the isoelectric point of BSA (pH 4.7). The results of the dynamic light scattering and protein adsorption measurements clearly demonstrated that the observed turbidity enhancement was caused by albumin sorption on the surface of Ln(OH)3 and colloid particles bridging via adsorbed protein molecules. Upon pH increase from 4.5 to 6.5, albumin adsorption on lanthanide colloids was observed, while the following increase of pH from 6.5 to 9.5 led to protein desorption. The predominant role of the electrostatic interactions in the adsorption and desorption processes were revealed in the zeta-potential measurements. No reversibility was observed upon decreasing pH from 9.5 to 4.5 that was suggested to be due to the other interaction mechanisms present in the system. It was shown that while for all lanthanide ions the interaction mechanism with BSA was similar, its manifestation in the optical properties of the system was significantly different. This was interpreted as a consequence of the differences in lanthanides hydrolysis constants. Copyright © 2016 Elsevier B.V. All rights reserved.

  3. Investigation of the interaction of deltamethrin (DM) with human serum albumin by multi-spectroscopic method

    Science.gov (United States)

    Wang, Jiaman; Ma, Liang; Zhang, Yuhao; Jiang, Tao

    2017-02-01

    The interaction of Deltamethrin (DM) with human serum albumin (HSA) under the condition of simulating human blood pH environment (pH = 7.4) was investigated by fluorescence, UV-Vis absorbance and circular dichroism (CD) spectroscopy. It was shown that DM was a static quencher of HSA. The binding constants (Ka) are 3.598 × 104 L mol-1 (25 °C); the thermodynamic parameters (ΔH = -3.269 × 104 kJ mol-1, ΔS = -22.81 kJ mol-1 k-1, ΔG = -25889.8 kJ mol-1) obtained with the thermodynamic equation. The hydrogen bond and Vander Waals were the main driving force. The effect of DM on the conformation of HSA was observed by three-dimensional (3D) fluorescence and circular dichroism spectra, indicating that the interaction between DM and HSA was achieved through the binding of DM with the tryptophan and tyrosine residues of HSA. The study on the interaction of DM and Bovine Serum Albumin (BSA) was researched and compared. Difference exists in the interactions of with each of the serum albumins. We will verify and supplement that DM residue in animals and human metabolism, toxicology and other mechanisms are different.

  4. Interactions of cephalexin with bovine serum albumin: displacement reaction and molecular docking

    Directory of Open Access Journals (Sweden)

    Hamed Hamishehkar

    2016-09-01

    Conclusion: The outcomes of spectroscopic methods revealed that the conformation of BSA changed during drug-BSA interaction. The results of FRET propose that CPL quenches the fluorescence of BSA by static quenching and FRET. The displacement study showed that phenylbutazon and ketoprofen displaced CPL, indicating that its binding site on albumin is site I and Gentamicin cannot be displaced from the binding site of CPL. All results of molecular docking method agreed with the results of experimental data.

  5. Interactions between 4-(2-dimethylaminoethyloxy)-N-octadecyl-1,8-naphthalimide and serum albumins: Investigation by spectroscopic approach

    Energy Technology Data Exchange (ETDEWEB)

    Sun Yang; Wei Song [School of Chemical Engineering, Northwest University, No. 229 Taibai North Road, Xi' an, Shaanxi 710069 (China); Zhao Yingyong [Biomedicine Key Laboratory of Shaanxi Province, Northwest University, No. 229 Taibai North Road, Xi' an, Shaanxi 710069 (China); Hu Xiaoyun, E-mail: hxy3275@nwu.edu.cn [Department of Physics, Northwest University, No. 229 Taibai North Road, Xi' an, Shaanxi 710069 (China); Fan Jun, E-mail: fanjun@nwu.edu.cn [School of Chemical Engineering, Northwest University, No. 229 Taibai North Road, Xi' an, Shaanxi 710069 (China)

    2012-04-15

    detection limit (3{sigma}) for HSA was 1.12 Multiplication-Sign 10{sup -10} M, for BSA it was 0.92 Multiplication-Sign 10{sup -10} M and for EA it was 4.33 Multiplication-Sign 10{sup -10} M. The effect of metal cations on the fluorescence spectra of DON in ethanol was also investigated. The method has been applied to detect the total proteins in human serum samples and the results were in good agreement with those reported by the hospital. - Highlights: Black-Right-Pointing-Pointer 4-(2-Dimethylaminoethyloxy)-N-octadecyl-1,8-naphthalimide (DON) was synthesized. Black-Right-Pointing-Pointer Effect of solvents on spectral characteristic of DON was investigated. Black-Right-Pointing-Pointer Interactions of DON with serum albumin were studied by spectral method. Black-Right-Pointing-Pointer A fluorometric method for determination of protein was developed.

  6. SERS spectroscopy of kaempferol and galangin under the interaction of human serum albumin with adsorbed silver nanoparticles

    Science.gov (United States)

    Zhang, Wei; Bai, Xueyuan; Wang, Yingping; Zhao, Bing; Zhao, Daqing; Zhao, Yu

    Raman and surface-enhanced Raman scattering (SERS) spectroscopy were employed to probe the interaction of the flavonol drugs, kaempferol and galangin, with human serum albumin (HSA). SERS spectra of both flavonol derivatives were obtained from a colloidal silver surface in physiological condition, based on the high performance of the enhanced substrate, the most enhanced modes of kaempferol and galangin were those with certain motions perpendicular to the metal surface. The SERS spectra were allowed to predict similar orientation geometry for both of the drugs on the colloidal surface with minor difference. In addition, both flavonols-HSA complexes were prepared in different concentration ratios and the orientated differences between kaempferol and galangin were investigated by SERS.

  7. Synergistic interaction between prolonged increased glycemic exposure and mildly increased urinary albumin excretion on diabetic retinopathy.

    Science.gov (United States)

    Moon, Shinje; Yoo, Hyung-Joon; Ahn, You-Hern; Kim, Gheun-Ho; Yu, Jae Myung; Park, Joon-Sung

    2018-01-01

    The association of mild increase in urinary albumin excretion with diabetic retinopathy (DR) in clinical studies is controversial. The aim of this study is to clarify the interaction between increased glycemic exposure and mild increase in urinary albumin excretion on risk of DR.Data were collected from the National Health and Nutrition Examination Survey (NHANES) from 2005 to 2012. Overall, data from 953 participants without microalbuminuria (477 men and 476 women) were assessed. Logistic regression analysis was constructed to evaluate the association between DR and related clinical parameters, including urinary albumin-creatinine ratio (UACR, mg/g creatinine). The biological interaction of glycemic status and UACR on DR was evaluated by 3 indices: RERI, the relative excess risk due to the interaction; AP, the attributable proportion due to the interaction; and S, the additive interaction index of synergy.We found that UACR, glycated hemoglobin (HbA1c), and diabetic duration were deeply associated with increased risk of DR (UACR, odds ratio [OR] = 1.04, 95% confidence interval [CI] = 1.02-1.07; HbA1c, OR = 1.16, 95% CI = 1.04-1.30; diabetic duration, OR = 1.06, 95% CI = 1.04-1.07). Furthermore, our interaction analysis demonstrated that synergistic interaction between HbA1c and UACR on development of DR was prominent in participants with diabetic duration of ≥10 years (adjusted RERI = 0.92, 95% CI = 0.10-1.74; adjusted AP = 0.29, 95% CI = -0.82-1.41; adjusted S = 1.76, 95% CI = 1.27-2.25), but not subjects with shorter diabetic duration.These findings imply that there is the interaction between prolonged hyperglycemic exposure and increased urinary albumin excretion may exert additive synergistic effect on vascular endothelial dysfunction in the eye, even before the appearance of overt diabetic nephropathy. Copyright © 2017 The Authors. Published by Wolters Kluwer Health, Inc. All rights reserved.

  8. Interaction of fibrinogen and albumin with titanium dioxide nanoparticles of different crystalline phases

    Science.gov (United States)

    Marucco, Arianna; Fenoglio, Ivana; Turci, Francesco; Fubini, Bice

    2013-04-01

    TiO2 nanoparticles (NPs) are contained in different kinds of industrial products including paints, self-cleaning glasses, sunscreens. TiO2 is also employed in photocatalysis and it has been proposed for waste water treatment. Micrometric TiO2 is generally considered a safe material, while there is concern on the possible health effects of nanometric titania. Due to their small size NPs may migrate within the human body possibly entering in the blood stream. Therefore studies on the interaction of NPs with plasma proteins are needed. In fact, the interaction with proteins is believed to ultimately influences the NPs biological fate. Fibrinogen and albumin are two of the most abundant plasma proteins. They are involved in several important physiological functions. Furthermore, fibrinogen is known to trigger platelet adhesion and inflammation. For these reasons the study of the interaction between these protein and nanoparticles is an important step toward the understanding of the behavior of NPs in the body. In this study we investigated the interaction of albumin and fibrinogen with TiO2 nanoparticles of different crystal phases (rutile and anatase) using an integrated set of techniques. The amount of adsorbed fibrinogen and albumin for each TiO2 surface was investigated by using the bicinchoninic acid assay (BCA). The variation of the surface charge of the NP-protein conjugates respect to the naked NPs was used to indirectly estimate both surface coverage and reversibility of the adsorption upon dilution. Surface charge was monitored by measuring the ζ potential with a conventional electrophoretic light scattering (ELS) system. The extent of protein deformation was evaluated by Raman Spectroscopy. We found that both proteins adsorb irreversibly against electrostatic repulsion, likely undergoing conformational changes or selective orientation upon adsorption. The size of primary particles and the particles aggregation rather than the crystal phase modulate the

  9. Interaction of fibrinogen and albumin with titanium dioxide nanoparticles of different crystalline phases

    International Nuclear Information System (INIS)

    Marucco, Arianna; Fenoglio, Ivana; Turci, Francesco; Fubini, Bice

    2013-01-01

    TiO 2 nanoparticles (NPs) are contained in different kinds of industrial products including paints, self-cleaning glasses, sunscreens. TiO 2 is also employed in photocatalysis and it has been proposed for waste water treatment. Micrometric TiO 2 is generally considered a safe material, while there is concern on the possible health effects of nanometric titania. Due to their small size NPs may migrate within the human body possibly entering in the blood stream. Therefore studies on the interaction of NPs with plasma proteins are needed. In fact, the interaction with proteins is believed to ultimately influences the NPs biological fate. Fibrinogen and albumin are two of the most abundant plasma proteins. They are involved in several important physiological functions. Furthermore, fibrinogen is known to trigger platelet adhesion and inflammation. For these reasons the study of the interaction between these protein and nanoparticles is an important step toward the understanding of the behavior of NPs in the body. In this study we investigated the interaction of albumin and fibrinogen with TiO 2 nanoparticles of different crystal phases (rutile and anatase) using an integrated set of techniques. The amount of adsorbed fibrinogen and albumin for each TiO 2 surface was investigated by using the bicinchoninic acid assay (BCA). The variation of the surface charge of the NP-protein conjugates respect to the naked NPs was used to indirectly estimate both surface coverage and reversibility of the adsorption upon dilution. Surface charge was monitored by measuring the ζ potential with a conventional electrophoretic light scattering (ELS) system. The extent of protein deformation was evaluated by Raman Spectroscopy. We found that both proteins adsorb irreversibly against electrostatic repulsion, likely undergoing conformational changes or selective orientation upon adsorption. The size of primary particles and the particles aggregation rather than the crystal phase modulate the

  10. Interaction of chlorogenic acids and quinides from coffee with human serum albumin.

    Science.gov (United States)

    Sinisi, Valentina; Forzato, Cristina; Cefarin, Nicola; Navarini, Luciano; Berti, Federico

    2015-02-01

    Chlorogenic acids and their derivatives are abundant in coffee and their composition changes between coffee species. Human serum albumin (HSA) interacts with this family of compounds with high affinity. We have studied by fluorescence spectroscopy the specific binding of HSA with eight compounds that belong to the coffee polyphenols family, four acids (caffeic acid, ferulic acid, 5-O-caffeoyl quinic acid, and 3,4-dimethoxycinnamic acid) and four lactones (3,4-O-dicaffeoyl-1,5-γ-quinide, 3-O-[3,4-(dimethoxy)cinnamoyl]-1,5-γ-quinide, 3,4-O-bis[3,4-(dimethoxy)cinnamoyl]-1,5-γ-quinide, and 1,3,4-O-tris[3,4-(dimethoxy)cinnamoyl]-1,5-γ-quinide), finding dissociation constants of the albumin-chlorogenic acids and albumin-quinides complexes in the micromolar range, between 2 and 30μM. Such values are comparable with those of the most powerful binders of albumin, and more favourable than the values obtained for the majority of drugs. Interestingly in the case of 3,4-O-dicaffeoyl-1,5-γ-quinide, we have observed the entrance of two ligand molecules in the same binding site, leading up to a first dissociation constant even in the hundred nanomolar range, which is to our knowledge the highest affinity ever observed for HSA and its ligands. The displacement of warfarin, a reference drug binding to HSA, by the quinide has also been demonstrated. Copyright © 2014 Elsevier Ltd. All rights reserved.

  11. Interaction of tea polyphenols with serum albumins: A fluorescence spectroscopic analysis

    International Nuclear Information System (INIS)

    Bose, Adity

    2016-01-01

    Interactions of some tea polyphenols, namely (−) Catechin (C), (−)-epicatechin (EC), (–) epicatechin-3-gallate (ECG), (−)-epigallocatechin (EGC) and (−)-epigallocatechin-3-gallate (EGCG) are outlined with the serum albumin proteins. These interactions had all resulted in binding with the proteins with a concomitant static quenching of the protein fluorescence. A fluorescence technique has been considered as the tool to comprehend the polyphenol–protein interactions mainly and simultaneously other spectroscopic techniques used to verify the results have been discussed. In this mini review the different types of equations usually employed to calculate the binding constant values have been outlined, namely, modified Stern Volmer plot, Scatchard plot and Lineweaver Burk equation, with their corresponding results. The n values (number of binding sites) had always been close to unity suggesting a 1:1 complexation with the polyphenols and the protein. A structural change in the polyphenols has been found to alter the binding constant value and the galloyl moiety attached to the C ring of the polyphenols have been found to play a crucial role in this regard. It has been found that an increase in galloyl moiety increases binding of the catechins with proteins. - Highlights: • Review on interactions of some tea polyphenols with the serum albumin proteins. • Tea polyphenols include Catechin, epigallocatechin-3-gallate, epigallocatechin, epicatechin-3-gallate and epicatechin. • Fluorescence spectroscopic technique is mainly outlined. • Binding constant studies have been given importance. • Galloyl moiety in the C ring is crucial in increasing binding constant.

  12. Mapping the interactions between the Alzheimer's Aβ-peptide and human serum albumin beyond domain resolution.

    Science.gov (United States)

    Algamal, Moustafa; Milojevic, Julijana; Jafari, Naeimeh; Zhang, William; Melacini, Giuseppe

    2013-10-01

    Human serum albumin (HSA) is a potent inhibitor of Aβ self-association and this novel, to our knowledge, function of HSA is of potential therapeutic interest for the treatment of Alzheimer's disease. It is known that HSA interacts with Aβ oligomers through binding sites evenly partitioned across the three albumin domains and with comparable affinities. However, as of this writing, no information is available on the HSA-Aβ interactions beyond domain resolution. Here, we map the HSA-Aβ interactions at subdomain and peptide resolution. We show that each separate subdomain of HSA domain 3 inhibits Aβ self-association. We also show that fatty acids (FAs) compete with Aβ oligomers for binding to domain 3, but the determinant of the HSA/Aβ oligomer interactions are markedly distinct from those of FAs. Although salt bridges with the FA carboxylate determine the FA binding affinities, hydrophobic contacts are pivotal for Aβ oligomer recognition. Specifically, we identified a site of Aβ oligomer recognition that spans the HSA (494-515) region and aligns with the central hydrophobic core of Aβ. The HSA (495-515) segment includes residues affected by FA binding and this segment is prone to self-associate into β-amyloids, suggesting that sites involved in fibrilization may provide a lead to develop inhibitors of Aβ self-association. Copyright © 2013 Biophysical Society. Published by Elsevier Inc. All rights reserved.

  13. An interaction of the functionalized closo-borates with albumins: The protein fluorescence quenching and calorimetry study

    International Nuclear Information System (INIS)

    Losytskyy, Mykhaylo Yu.; Kovalska, Vladyslava B.; Varzatskii, Oleg A.; Kuperman, Marina V.; Potocki, Slawomir; Gumienna-Kontecka, Elzbieta; Zhdanov, Andrey P.; Yarmoluk, Sergiy M.; Voloshin, Yan Z.; Zhizhin, Konstantin Yu.; Kuznetsov, Nikolai T.; Elskaya, Anna V.

    2016-01-01

    An interaction of the boron clusters closo-borates K 2 [B 10 H 10 ], K 2 [B 12 H 12 ] and their functionalized derivatives with serum proteins human (HSA) and bovine (BSA) albumins and immonoglobulin IgG as well as globular proteins β-lactoglobulin and lysozyme was characterized. The steady state and time resolved protein fluorescence quenching studies point on the binding of the closo-borate arylamine derivatives to serum albumins and discrimination of other proteins. The mechanism of the albumin fluorescence quenching by the closo-borate arylamine derivatives was proposed. The complex formation between albumin and the closo-borate molecules has been confirmed by isothermal titration calorimetry (ITC). The compound (K 2 [B 10 H 10 ]) and its arylamine derivative both interact with HSA, have close values of K a (1.4 and 1.2×10 3 M −1 respectively) and Gibbs energy (−17.9 and −17.5 kJ/mol respectively). However, the arylamine derivative forms complex with the higher guest/host binding ratio (4:1) comparing to the parent closo-borate (2:1). - Highlights: • Complex formation between boron clusters closo-borates and albumins was confirmed. • Functional substituent of closo-borate strongly affects its complex with albumins. • Binding of arylamine closo-borates essentially quench the albumin fluorescence. • Mechanism of tryptophan emission quenching by arylamine closo-borates was proposed.

  14. The interaction of human serum albumin with selected lanthanide and actinide ions: Binding affinities, protein unfolding and conformational changes.

    Science.gov (United States)

    Ali, Manjoor; Kumar, Amit; Kumar, Mukesh; Pandey, Badri N

    2016-04-01

    Human serum albumin (HSA), the most abundant soluble protein in blood plays critical roles in transportation of biomolecules and maintenance of osmotic pressure. In view of increasing applications of lanthanides- and actinides-based materials in nuclear energy, space, industries and medical applications, the risk of exposure with these metal ions is a growing concern for human health. In present study, binding interaction of actinides/lanthanides [thorium: Th(IV), uranium: U(VI), lanthanum: La(III), cerium: Ce(III) and (IV)] with HSA and its structural consequences have been investigated. Ultraviolet-visible, Fourier transform-infrared, Raman, Fluorescence and Circular dichroism spectroscopic techniques were applied to study the site of metal ions interaction, binding affinity determination and the effect of metal ions on protein unfolding and HSA conformation. Results showed that these metal ions interacted with carbonyl (CO..:)/amide(N..-H) groups and induced exposure of aromatic residues of HSA. The fluorescence analysis indicated that the actinide binding altered the microenvironment around Trp214 in the subdomain IIA. Binding affinity of U(VI) to HSA was slightly higher than that of Th(IV). Actinides and Ce(IV) altered the secondary conformation of HSA with a significant decrease of α-helix and an increase of β-sheet, turn and random coil structures, indicating a partial unfolding of HSA. A correlation was observed between metal ion's ability to alter HSA conformation and protein unfolding. Both cationic effects and coordination ability of metal ions seemed to determine the consequences of their interaction with HSA. Present study improves our understanding about the protein interaction of these heavy ions and their impact on its secondary structure. In addition, binding characteristics may have important implications for the development of rational antidote for the medical management of health effects of actinides and lanthanides. Copyright © 2016 Elsevier

  15. Thermodynamic Study of Human Serum Albumin upon Interaction with Ytterbium (III

    Directory of Open Access Journals (Sweden)

    G. Rezaei Behbehani

    2013-01-01

    Full Text Available Complexation reaction between Yb3+ and human serum albumin is examined using isothermal titration calorimetry (ITC. The extension solvation theory was used to reproduce the enthalpies of HAS + Yb3+ interactions over the whole range of Yb3+ concentrations. The binding parameters recovered from this model were attributed to the structural change of HSA. The results show that Yb3+ ions bind to HSA with three equivalent affinity sites. It was found that in the high concentrations of the ytterbium ions, the HSA structure was destabilized.

  16. {beta}-Lactam antibiotics epitope mapping with STD NMR spectroscopy: a study of drug-human serum albumin interaction

    Energy Technology Data Exchange (ETDEWEB)

    Milagre, Cintia D. F.; Cabeca, Luis F.; Almeida, Wanda P.; Marsaioli, Anita J., E-mail: cmilagre@rc.unesp.br [Institute of Chemistry, University of Campinas (UNICAMP), SP (Brazil)

    2012-03-15

    Molecular recognition events are key issues in many biological processes. STD NMR (saturation transfer difference nuclear magnetic resonance spectroscopy) is one of the techniques used to understand such biological interactions. Herein, we have investigated the interactions of four {beta}-lactam antibiotics belonging to two classes (cephalosporins and penicillins) with human serum albumin (HSA) by {sup 1}H STD NMR revealing that the interaction between the aromatic moiety and HSA is responsible for the binding efficiency. Thus, the structural differences from the five to six-membered thio ring in penicillins and cephalosporins do not seem to influence antibiotic albumin interactions. (author)

  17. The application of two-dimensional fluorescence correlation spectroscopy on the interaction between bovine serum albumin and prulifloxacin

    OpenAIRE

    Xue, Mao-Yun; Yang, Ai-Ping; Ma, Mei-Hua; Li, Xiao-Hua

    2009-01-01

    The interaction between bovine serum albumin (BSA) and prulifloxacin was investigated by ultraviolet spectrophotometer (UV) and fluorescence spectroscopy in this paper. Two-dimensional (2D) correlation spectroscopy was applied to the analysis of fluorescence spectra. The results of spectroscopic measurements suggested that prulifloxacin (PL) have a strong ability to quench the intrinsic fluorescence of bovine serum albumin through static quenching procedure. Thermodynamic parameter enthalpy c...

  18. Fluorescence resonance energy transfer: A promising tool for investigation of the interaction between 1-anthracene sulphonate and serum albumins

    International Nuclear Information System (INIS)

    Banerjee, Paltu; Ghosh, Saptaparni; Sarkar, Arindam; Bhattacharya, Subhash Chandra

    2011-01-01

    This present investigation has revealed that steady state as well as time-resolved fluorescence techniques can serve as highly sensitive monitors for exploring the interaction of fluorescent probe 1-anthracene sulphonate (1-AS) with model transport proteins, bovine serum albumin (BSA) and human serum albumin (HSA).We have focused on fluorescence resonance energy transfer (FRET) between excited tryptophan in transport proteins to 1-AS, for the study of relaxation dynamics of biological molecules.

  19. Characterization of the Interaction between Eupatorin and Bovine Serum Albumin by Spectroscopic and Molecular Modeling Methods

    Science.gov (United States)

    Xu, Hongliang; Yao, Nannan; Xu, Haoran; Wang, Tianshi; Li, Guiying; Li, Zhengqiang

    2013-01-01

    This study investigated the interaction between eupatorin and bovine serum albumin (BSA) using ultraviolet-visible (UV-vis) absorption, fluorescence, synchronous fluorescence, circular dichroism (CD) spectroscopies, and molecular modeling at pH 7.4. Results of UV-vis and fluorescence spectroscopies illustrated that BSA fluorescence was quenched by eupatorin via a static quenching mechanism. Thermodynamic parameters revealed that hydrophobic and electrostatic interactions played major roles in the interaction. Moreover, the efficiency of energy transfer, and the distance between BSA and acceptor eupatorin, were calculated. The effects of eupatorin on the BSA conformation were analyzed using UV-vis, CD, and synchronous fluorescence. Finally, the binding of eupatorin to BSA was modeled using the molecular docking method. PMID:23839090

  20. Interaction of Palmitic Acid with Metoprolol Succinate at the Binding Sites of Bovine Serum Albumin

    Directory of Open Access Journals (Sweden)

    Mashiur Rahman

    2014-12-01

    Full Text Available Purpose: The aim of this study was to characterize the binding profile as well as to notify the interaction of palmitic acid with metoprolol succinate at its binding site on albumin. Methods: The binding of metoprolol succinate to bovine serum albumin (BSA was studied by equilibrium dialysis method (ED at 27°C and pH 7.4, in order to have an insight in the binding chemistry of the drug to BSA in presence and absence of palmitic acid. The study was carried out using ranitidine as site-1 and diazepam as site-2 specific probe. Results: Different analysis of binding of metoprolol succinate to bovine serum albumin suggested two sets of association constants: high affinity association constant (k1 = 11.0 x 105 M-1 with low capacity (n1 = 2 and low affinity association (k2 = 4.0×105 M-1 constant with high capacity (n2 = 8 at pH 7.4 and 27°C. During concurrent administration of palmitic acid and metoprolol succinate in presence or absence of ranitidine or diazepam, it was found that palmitic acid displaced metoprolol succinate from its binding site on BSA resulting reduced binding of metoprolol succinate to BSA. The increment in free fraction of metoprolol succinate was from 26.27% to 55.08% upon the addition of increased concentration of palmitic acid at a concentration of 0×10-5 M to 16×10-5 M. In presence of ranitidine and diazepam, palmitic acid further increases the free fraction of metoprolol succinate from 33.05% to 66.95% and 40.68% to 72.88%, respectively. Conclusion: This data provided the evidence of interaction at higher concentration of palmitic acid at the binding sites on BSA, which might change the pharmacokinetic properties of metoprolol succinate.

  1. A multispectroscopic and molecular docking investigation of the binding interaction between serum albumins and acid orange dye

    Science.gov (United States)

    Naveenraj, Selvaraj; Solomon, Rajadurai Vijay; Mangalaraja, Ramalinga Viswanathan; Venuvanalingam, Ponnambalam; Asiri, Abdullah M.; Anandan, Sambandam

    2018-03-01

    The interaction of Acid Orange 10 (AO10) with bovine serum albumin (BSA) was investigated comparatively with that of human serum albumin (HSA) using multispectroscopic techniques for understanding their toxic mechanism. Further, density functional theory calculations and docking studies have been carried out to gain more insights into the nature of interactions existing between AO10 and serum albumins. The fluorescence results suggest that AO10 quenched the fluorescence of BSA through the combination of static and dynamic quenching mechanism. The same trend was followed in the interaction of AO10 with HSA. In addition to the type of quenching mechanism, the fluorescence spectroscopic results suggest that the binding occurs near the tryptophan moiety of serum albumins and the binding. AO10 has more binding affinity towards BSA than HSA. An AO10-Trp model has been created to explicitly understand the Csbnd Htbnd π interactions from Bader's quantum theory of atoms in molecules analysis which confirmed that AO10 bind more strongly with BSA than that of HSA due to the formation of three hydrogen bonds with BSA whereas it forms two hydrogen bonds in the case of HSA. These obtained results provide an in-depth understanding of the interaction of the acid azo dye AO10 with serum albumins. This interaction study provides insights into the underlying reasons for toxicity of AO10 relevant to understand its effect on bovids and humans during the blood transportation process.

  2. [Study of interaction between sorbitol and bovine serum albumin by fluorescence spectrometry].

    Science.gov (United States)

    Li, Dan; Jiang, Xin-min; Yan, Zheng-yu

    2008-06-01

    The interaction of sorbitol and bovine serum album (BSA) was studied by fluorescence and ultraviolet absorption spectra. As it is well known to us, the interactional analysis between small molecular drug and biology macromolecule (such as protein, DNA, etc) is one of the important interactional analyses, which can not only offer new biological view but also supply chance for chemist and biochemist to synthesize new drug capable of regulating the biology process effectively. In the present paper, fluorescence spectrophotometry was first employed to study the interaction between BSA and sorbitol. At the same time, the synchronous fluorescence spectroscopy was adopted to review the configuration of BSA influenced by sorbitol, which provides important significance for clinical medication. The results show that sorbitol has strongly quenched the fluorescence of bovine serum albumin in natural physiological condition, the quenching mechanism is a static quenching procedure at different temperatures and drug concentration, and the variational absorption spectra also proves this deduction. At the same time, this article has also examined the influences of sorbitol on the fluorescence quenching of bovine serum albumin at different temperatures and drug concentration. The binding constants and the number of binding sites between sorbitol and BSA were calculated at different temperatures. Furthermore, the enthalpy and entropy changes in the interaction of sorbitol and bovine serum album were also obtained by the equations of Stern-Volmer and Lineweaver-Burk. From the thermodynamic parameters, it can be judged that the primary binding power between sorbitol and BSA is electrostatic force. Moreover, the synchronous fluorescence spectroscopy was applied to examine the effect of sorbitol on the configuration of BSA. The alterative configuration of BSA may be induced by the hydrophobicity environment of tyrosine with the increase in drug concentration. In conclusion, the

  3. [Investigation on the interaction between pentadecafluorooctanoic acid and human serum albumin by capillary electrophoresis].

    Science.gov (United States)

    Gu, Yi; Guo, Ming; Lü, Da; Hou, Ping; Yin, Xinxin

    2018-01-08

    Capillary electrophoresis (CE) has been used to establish the analytical method of interaction between pentadecafluorooctanoic acid (PFOA) and human serum albumin (HSA). Under the physiological conditions, the interaction model of PFOA and HSA were constructed. Mobility method, plug-plug kinetic (PPK) method and simplified Hummel-Dreyer method were used to determine the interaction between derivatives and HSA. Non-linear regression, Scatchard equation and Klotz equation were adopted to obtain the interaction parameters. The results showed that all the three methods can be used to analyze the interaction of PFOA-HSA system. According to the interaction parameters, the most suitable CE method is simplified Hummel-Dreyer method while the most suitable theoretical equation is non-linear regression. The binding parameters indicated that the interaction of PFOA-HSA system has only one type of binding sites and the binding is stable. The research results have illustrated the interaction between HSA and PFOA, and provided a beneficial reference for in-depth research of the toxic mechanism of PFOA.

  4. A model based on spectrofluorimetry to study the interaction between glyphosate and serum albumin of Salminus brasiliensis

    Science.gov (United States)

    Escobar, Marta Araujo Cyrino; Cortez, Celia Martins; Silva, Dilson; Neto, Jayme da Cunha Bastos

    2017-11-01

    The aim of this work is to initiate an investigation on the albumin of Salminus brasiliensis (gold fish) as a biomarker of environmental actions of glyphosate. We started using a mathematical-computational model based on spectrofluorimetric measurements to study the interaction of glyphosate with gold fish albumin and human serum albumin. Salminus brasiliensis is a migratory freshwater fish species found in southern and central-western Brazil, mainly in the Prata river basin, where most of soybean plantations are set. Glyphosate is a very used herbicide in this type of crop. Differently from the organophosphorate methyl parathion, glyphosate does not form complex with HSA, and the quenching constants estimated for its binding with gold fish albumin at 20 °C and 25 °C is 1.3(± 0.3) × 104 / M e 2.5 (± 0.3) × 104 / M, respectively.

  5. A calorimetric study on interactions of colchicine with human serum albumin

    Science.gov (United States)

    Zhao, Qiang; Xu, Xiang-Yu; Sun, Xiang-Jun; Liu, Min; Sun, De-Zhi; Li, Lin-Wei

    2009-08-01

    Interaction of colchicine (COL) with human serum albumin (HSA) in buffer solutions (pH 7.2) has been investigated by isothermal titration calorimetry (ITC) combined with circular dichroism (CD) and UV-vis spectra. Heats of the interactions have been determined at 298.15 K. Based on the calorimetric data and reasonable suppositions for the bio-macromolecule - ligand binding process, the equilibrium constants, standard changes of enthalpy, entropy and Gibbs free energy of the processes are obtained. The results show that there are two classes of ligand binding sites. The first-class binding is mainly driven by entropy, while the second-class binding is synergistically driven by entropy and enthalpy. Circular dichroism (CD) and UV-vis spectra show that COL can change the secondary structure of HSA molecule.

  6. Interaction of the flavonoid hesperidin with bovine serum albumin: A fluorescence quenching study

    Energy Technology Data Exchange (ETDEWEB)

    Wang Yanqing [Jiangsu Provincial Key Laboratory of Coastal Wetland Bioresources and Environmental Protection, Yancheng Normal College, Yancheng City, Jiangsu Province 224002 (China) and Institute of Applied Chemistry and Environmental Engineering, Yancheng Normal College, Yancheng City, Jiangsu Province 224002 (China)]. E-mail: wyqing76@126.com; Zhang Hongmei [Institute of Applied Chemistry and Environmental Engineering, Yancheng Normal College, Yancheng City, Jiangsu Province 224002 (China); Zhang Gencheng [Jiangsu Provincial Key Laboratory of Coastal Wetland Bioresources and Environmental Protection, Yancheng Normal College, Yancheng City, Jiangsu Province 224002 (China); Institute of Applied Chemistry and Environmental Engineering, Yancheng Normal College, Yancheng City, Jiangsu Province 224002 (China); Tao Weihua [Institute of Applied Chemistry and Environmental Engineering, Yancheng Normal College, Yancheng City, Jiangsu Province 224002 (China); Tang Shuhe [Institute of Applied Chemistry and Environmental Engineering, Yancheng Normal College, Yancheng City, Jiangsu Province 224002 (China)

    2007-09-15

    The interaction between the flavonoid hesperidin and bovine serum albumin (BSA) was investigated by fluorescence and UV/Vis absorption spectroscopy. The results revealed that hesperidin caused the fluorescence quenching of BSA through a static quenching procedure. The hydrophobic and electrostatic interactions play a major role in stabilizing the complex. The binding site number n, and apparent binding constant K {sub A}, corresponding thermodynamic parameters {delta}G {sup o}, {delta}H {sup o}, {delta}S {sup o} at different temperatures were calculated. The distance r between donor (BSA) and acceptor (hesperidin) was obtained according to fluorescence resonance energy transfer. The effect of Cu{sup 2+}, Zn{sup 2+}, Ni{sup 2+}, Co{sup 2+}, and Mn{sup 2+} on the binding constants between hesperidin and BSA were studied. The effect of hesperidin on the conformation of BSA was analyzed using synchronous fluorescence spectroscopy and UV/Vis absorption spectroscopy.

  7. Interaction of diuron to human serum albumin: Insights from spectroscopic and molecular docking studies.

    Science.gov (United States)

    Chen, Huilun; Rao, Honghao; Yang, Jian; Qiao, Yongxiang; Wang, Fei; Yao, Jun

    2016-01-01

    This investigation was undertaken to determine the interaction of diuron with human serum albumin (HSA) was studied by monitoring the spectral behavior of diuron-HSA system. The fluorescence of HSA at 340 nm excited at 230 nm was obviously quenched by diuron due to dynamic collision and the quenching constant was of the order of 10(4) L mol(-1) at 310 K. However, no fluorescence quenching was observed when excited at 280 nm. Thermodynamic investigations revealed that the combination between diuron and HSA was entropy driven by predominantly hydrophobic interactions. The binding of diuron induced the drastic reduction in α-helix conformation and the significant enhancement in β-turn conformation of HSA. In addition, both sites marker competition study and molecular modeling simulation evidenced the binding of diuron to HSA primarily took place in subdomain IIIA (Sudlow's site II).

  8. Docking simulations and spectroscopy of the interactions of ellagic acid and oleuropein with human serum albumin

    Energy Technology Data Exchange (ETDEWEB)

    He, Jiawei; Wang, Qing; Zhang, Lili; Lin, Xia; Li, Hui, E-mail: lihuilab@sina.com

    2014-10-15

    The primary objective of this study is to evaluate the interactions of ellagic acid (EA) and oleuropein (OLE) with human serum albumin (HSA). Plasma protein binding model prediction and molecular modeling suggest that EA binds to HSA stronger than OLE, and that both interact with the binding pocket of HSA subdomain IIA. Furthermore, fluorescence spectroscopy confirmed that EA has a stronger HSA binding affinity than OLE. Three-dimensional fluorescence spectroscopy and CD spectroscopy, analyzed using DichroWeb, showed that the binding of EA and OLE to HSA induce conformational changes. - Highlights: • Two drugs were extracted and characterized by us. • DS 3.1 was used to analyze the binding ability and binding sites. • DICHROWEB was used to analyze CD data.

  9. Hydrophobic interaction adsorption of hen egg white proteins albumin, conalbumin, and lysozyme.

    Science.gov (United States)

    Rojas, Edwin E Garcia; dos Reis Coimbra, Jane S; Minim, Luis A; Saraiva, Sérgio H; da Silva, César A Sodré

    2006-08-18

    Hydrophobic adsorption equilibrium data of the hen egg white proteins albumin, conalbumin, and lysozyme were obtained in batch systems, at 25 degrees C, using the Streamline Phenyl resin as adsorbent. The influence of three types of salt, NaCl, Na(2)SO(4), or (NH(4))(2)SO(4), and their concentration on the equilibrium data were evaluated. The salt Na(2)SO(4) showed the higher interaction with the studied proteins, thus favoring the adsorption of proteins by the adsorbent, even though each type of salt interacted in a distinct manner with each protein. The isotherm models of Langmuir, Langmuir exponential, and Chen and Sun were well fitted to the equilibrium data, with no significant difference being observed at the 5% level of significance. The mass transfer model applied simulated correctly adsorption kinetics of the proteins under the studied conditions.

  10. Toxic interaction mechanism of two fluoroquinolones with serum albumin by spectroscopic and computational methods.

    Science.gov (United States)

    Qin, Pengfei; Pan, Xingren; Liu, Rutao; Hu, Changwei; Dong, Yuliang

    2017-11-02

    To evaluate the toxicity of two fluoroquinolones (FQs), ciprofloxacin (CPFX), and enrofloxacin (ENFX), at the protein level, their binding modes with bovine serum albumin (BSA) were characterized by multiple spectroscopic and molecular docking methods under simulated physiological conditions. On the basis of fluorescence spectra, we concluded that both FQs greatly quenched the fluorescence intensity of BSA, which was attributed to the formation of a moderately strong complex mainly through electrostatic interactions. Besides, CPFX posed more of an affinity threat than ENFX. The molecular docking methods further illustrated that both CPFX and ENFX could bind into the subdomain IIIA of BSA and interact with Arg 508 and Lys 437, the positively charged residues in protein. Furthermore, as shown by the synchronous fluorescence, UV-Visible absorption and circular dichroism data, both CPFX and ENFX could lead to the conformational and microenvironmental changes of BSA, which may affect its physiological function.

  11. Fluorescence and Docking Studies of the Interaction between Human Serum Albumin and Pheophytin

    Directory of Open Access Journals (Sweden)

    Otávio Augusto Chaves

    2015-10-01

    Full Text Available In the North of Brazil (Pará and Amazonas states the leaves of the plant Talinum triangulare (popular: cariru replace spinach as food. From a phytochemical point of view, they are rich in compounds of the group of pheophytins. These substances, related to chlorophyll, have photophysical properties that give them potential application in photodynamic therapy. Human serum albumin (HSA is one of the main endogenous vehicles for biodistribution of molecules by blood plasma. Association constants and thermodynamic parameters for the interaction of HSA with pheophytin from Talinum triangulare were studied by UV-Vis absorption, fluorescence techniques, and molecular modeling (docking. Fluorescence quenching of the HSA’s internal fluorophore (tryptophan at temperatures 296 K, 303 K, and 310 K, resulted in values for the association constants of the order of 104 L∙mol−1, indicating a moderate interaction between the compound and the albumin. The negative values of ΔG° indicate a spontaneous process; ΔH° = 15.5 kJ∙mol−1 indicates an endothermic process of association and ΔS° = 0.145 kJ∙mol−1∙K−1 shows that the interaction between HSA and pheophytin occurs mainly by hydrophobic factors. The observed Trp fluorescence quenching is static: there is initial non-fluorescent association, in the ground state, HSA:Pheophytin. Possible solution obtained by a molecular docking study suggests that pheophytin is able to interact with HSA by means of hydrogen bonds with three lysine and one arginine residues, whereas the phytyl group is inserted in a hydrophobic pocket, close to Trp-214.

  12. Interaction of phenylbutazone and colchicine in binding to serum albumin in rheumatoid therapy: 1H NMR study

    Science.gov (United States)

    Maciążek-Jurczyk, M.; Sułkowska, A.; Bojko, B.; Równicka-Zubik, J.; Sułkowski, W. W.

    2009-09-01

    The monitoring of drug concentration in blood serum is necessary in multi-drug therapy. Mechanism of drug binding with serum albumin (SA) is one of the most important factors which determine drug concentration and its transport to the destination tissues. In rheumatoid diseases drugs which can induce various adverse effects are commonly used in combination therapy. Such proceeding may result in the enhancement of those side effects due to drug interaction. Interaction of phenylbutazone and colchicine in binding to serum albumin and competition between them in gout has been studied by proton nuclear magnetic resonance ( 1H NMR) technique. The aim of the study was to determine the low affinity binding sites, the strength and kind of interaction between serum albumin and drugs used in combination therapy. The study of competition between phenylbutazone and colchicine in binding to serum albumin points to the change of their affinity to serum albumin in the ternary systems. This should be taken into account in multi-drug therapy. This work is a subsequent part of the spectroscopic study on Phe-COL-SA interactions [A. Sułkowska, et al., J. Mol. Struct. 881 (2008) 97-106].

  13. Interactions between epinastine and human serum albumin: Investigation by fluorescence, UV-vis, FT-IR, CD, lifetime measurement and molecular docking

    Science.gov (United States)

    Ariga, Girish G.; Naik, Praveen N.; Chimatadar, Shivamurti A.; Nandibewoor, Sharanappa T.

    2017-06-01

    The fluorescence quenching of human serum albumin (HSA) by epinastine hydrochloride (EPN) at pH 7.4 buffer was studied using absorption, fluorescence quenching, time-resolved, circular-dichroism, synchronous and molecular docking studies have been employed in the system. The fluorescence quenching study revealed that the static quenching mechanism was involved in the interaction of EPN with human serum albumin. The value number of binding sites, n, is close to unity, EPN-HSA, indicated the presence of a single class of binding site for the drug in protein. The binding constant value of EPN_HSA was observed to be 2.72 × 104 M-1 at 298 K. The spectral results attest that the binding of EPN-HSA induced conformational changes in the HSA. The metal ions viz., Ca2+, Co2+, Cu2+, Ni2+ and Zn2+ were found to influence the binding of the EPN to HSA. Based on the Forster's theory of non-radiation energy transfer, the binding average distance, r, between the donor (HSA) and acceptor (EPN) was found to be 4.33 nm. The circular dichroism data revealed that the presence of EPN decreased the α-helix content of serum albumin, which indicated conformation changes in HSA upon interaction with EPN.

  14. Investigation on the interaction between bovine serum albumin and 2,2-diphenyl-1-picrylhydrazyl

    Energy Technology Data Exchange (ETDEWEB)

    Li, Xiangrong [Department of Chemistry, School of Basic Medicine, Xinxiang Medical University, Xinxiang, Henan 453003 (China); Chen, Dejun; Wang, Gongke [School of Chemistry and Chemical Engineering, Key Laboratory of Green Chemical Media and Reactions, Ministry of Education, Henan Normal University, 46 Jian-she Road, Mu Ye District, Xinxiang, Henan 453007 (China); Lu, Yan, E-mail: 1842457577@qq.com [School of Chemistry and Chemical Engineering, Key Laboratory of Green Chemical Media and Reactions, Ministry of Education, Henan Normal University, 46 Jian-she Road, Mu Ye District, Xinxiang, Henan 453007 (China)

    2014-12-15

    Albumin represents a very abundant and important circulating antioxidant in plasma. In this paper, the ability of bovine serum albumin (BSA) to scavenge 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical has been investigated using UV–vis absorption spectra. The result shows that the antioxidant activity of BSA against DPPH radical is similar to glutathione and the value of IC{sub 50} is 5.153×10{sup −5} mol L{sup −1}. The interaction between BSA and DPPH has been investigated without or with the eight popular antioxidants (L-ascorbic acid, α-tocopherol, glutathione, melatonin, (+)-catechin hydrate, procyanidine B3, β-carotene and astaxanthin) by means of fluorescence spectroscopy and circular dichroism (CD) spectroscopy. The fluorescence experiments show that DPPH quenches the fluorescence intensity of BSA through a static mechanism. The quenching process of DPPH with BSA is easily affected by the eight antioxidants, however, they cannot change the quenching mechanism of DPPH with BSA. Additionally, as shown by synchronous fluorescence spectroscopy and CD, DPPH may induce conformational and microenvironmental changes of BSA. - Highlights: • The antioxidant activity of BSA against DPPH is similar to glutathione. • DPPH can quench the fluorescence of BSA through a static quenching. • One molecule of DPPH radical reduced by one molecule of BSA. • The eight antioxidants cannot change the quenching mechanism of DPPH with BSA. • The binding parameters are decreased by the introduction of the eight antioxidants.

  15. Multi-spectroscopic investigation of the binding interaction of fosfomycin with bovine serum albumin

    Directory of Open Access Journals (Sweden)

    Manjunath D. Meti

    2015-08-01

    Full Text Available The interaction between fosfomycin (FOS and bovine serum albumin (BSA has been investigated effectively by multi-spectroscopic techniques under physiological pH 7.4. FOS quenched the intrinsic fluorescence of BSA via static quenching. The number of binding sites n and observed binding constant KA were measured by the fluorescence quenching method. The thermodynamic parameters ΔG0, ΔH0 and ΔS0 were calculated at different temperatures according to the van’t Hoff equation. The site of binding of FOS in the protein was proposed to be Sudlow’s site I based on displacement experiments using site markers viz. warfarin, ibuprofen and digitoxin. The distance r between the donor (BSA and acceptor (FOS molecules was obtained according to the Förster theory. The effect of FOS on the conformation of BSA was analyzed using synchronous fluorescence spectra (SFS, circular dichroism (CD and 3D fluorescence spectra. A molecular modeling study further confirmed the binding mode obtained by the experimental studies. Keywords: Fosfomycin, Serum albumin, Spectroscopic methods, Synchronous fluorescence, 3D spectra

  16. Studies on binding interactions between clenbuterol hydrochloride and two serum albumins by multispectroscopic approaches in vitro.

    Science.gov (United States)

    Wang, Qin; Zhang, Shengrui

    2014-08-01

    In this study, binding properties of clenbuterol hydrochloride (CL) with human serum albumin (HSA) and bovine serum albumin (BSA) were examined using constant protein concentrations and various CL contents under physiological conditions. The binding parameters were confirmed using fluorescence quenching spectroscopy at various temperatures. The experimental results confirmed that the quenching mechanisms of CL and HSA/BSA were both static quenching processes. The thermodynamic parameters, namely, enthalpy change (ΔH) and entropy change (ΔS), were calculated according to the van't Hoff equation, which suggested that the electrostatic interactions were the predominant intermolecular forces in stabilizing the CL-HSA complex, and hydrogen bonds and van der Waals force were the predominant intermolecular forces in stabilizing the CL-BSA complex. Furthermore, the conformational changes of HSA/BSA in the presence of CL were determined using the data obtained from three-dimensional fluorescence spectroscopy, ultraviolet-visible absorption spectroscopy and circular dichroism spectroscopy. Copyright © 2013 John Wiley & Sons, Ltd.

  17. On the molecular interaction between albumin and ibuprofen: An AFM and QCM-D study.

    Science.gov (United States)

    Eleta-Lopez, Aitziber; Etxebarria, Juan; Reichardt, Niels-Christian; Georgieva, Radostina; Bäumler, Hans; Toca-Herrera, José L

    2015-10-01

    The adsorption of proteins on surfaces often results in a change of their structural behavior and consequently, a loss of bioactivity. One experimental method to study interactions on a molecular level is single molecular force spectroscopy that permits to measure forces down to the pico-newton range. In this work, the binding force between human serum albumin (HSA), covalently immobilized on glutaraldehyde modified gold substrates, and ibuprofen sodium salt was studied by means of single molecular force spectroscopy. First of all, a protocol was established to functionalize atomic force microscopy (AFM) tips with ibuprofen. The immobilization protocol was additionally tested by quartz crystal microbalance with dissipation (QCM-D) and contact angle measurements. AFM was used to characterize the adsorption of HSA on gold substrates, which lead to a packed monolayer of thickness slightly lower than the reported value in solution. Finally, single molecule spectroscopy results were used to characterize the binding force between albumin and ibuprofen and calculate the distance of the transition state (0.6 nm) and the dissociation rate constant (0.055 s(-1)). The results might indicate that part of the adsorbed protein still preserves its functionality upon adsorption. Copyright © 2015 Elsevier B.V. All rights reserved.

  18. Raman studies of the interactions of fibrous carbon nanomaterials with albumin

    Science.gov (United States)

    Wesełucha-Birczyńska, Aleksandra; Morajka, Krzysztof; Stodolak-Zych, Ewa; Długoń, Elżbieta; Dużyja, Maria; Lis, Tomasz; Gubernat, Maciej; Ziąbka, Magdalena; Błażewicz, Marta

    2018-05-01

    Adsorption or immobilization of proteins on synthetic surfaces is a key issue in the context of the biocompatibility of implant materials, especially those intended for the needs of cardiac surgery but also for the construction of biosensors or nanomaterials used as drug carriers. The subject of research was the analysis of Raman spectra of two types of fibrous carbon nanomaterials, of great potential for biomedical applications, incubated with human serum albumin (HSA). The first nanomaterial has been created on the layer of MWCNTs deposited by electrophoretic method (EPD) and then covered by thin film of pyrolytic carbon introduced by chemical vapor deposition process (CVD). The second material was formed from carbonized nanofibers prepared via electrospinning (ESCNFs) of polyacrylonitrile (PAN) precursor and then covered with pyrolytic carbon (CVD). The G-band blue-shift towards the position of about 1600 cm-1, observed for both studied surfaces, clearly indicates the albumin (HSA) adhesion to the surface. The G and G' (2D) peak shift was employed to assess the stress build up on the carbon nanomaterials. The surface nano- and micro-topography as well as the method of ordering the carbon nanomaterial has a significant influence on the mode of surface-protein interaction.

  19. Bovine serum albumin interacts with silver nanoparticles with a "side-on" or "end on" conformation.

    Science.gov (United States)

    Dasgupta, Nandita; Ranjan, Shivendu; Patra, Dhabaleswar; Srivastava, Priyanka; Kumar, Ashutosh; Ramalingam, Chidambaram

    2016-06-25

    As the nanoparticles (NPs) enter into the biological interface, they have to encounter immediate and first exposure to many proteins of different concentrations. The physicochemical interaction of NPs and proteins is greatly influenced not only by the number and type of proteins; but also the surface chemistry of NPs. To analyze the effects of NPs on proteins, the interaction between bovine serum albumin (BSA) and silver nanoparticles (AgNPs) at different concentrations were investigated. The interaction, BSA conformations, kinetics and adsorption were analyzed by UV-Visible spectrophotometer, dynamic light scattering (DLS), FT-IR spectroscopy and fluorescence quenching. DLS, FTIR and UV-visible spectrophotometric analysis confirms the interaction with minor alterations in size of the protein. Fluorescence quenching analysis confirms the side-on or end-on interaction of 1.5 molecules of BSA to AgNP. Further, pseudo-second order kinetics was determined with equilibrium contact-time of 30 min. The data of the present study determines the detailed evaluation of BSA adsorption on AgNP along with mechanism, kinetics and isotherm of the adsorption. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  20. Interaction of different thiol-capped CdTe quantum dots with bovine serum albumin

    International Nuclear Information System (INIS)

    Wang Qisui; Zhang Xiaolei; Zhou Xiaolan; Fang Tingting; Liu Pengfei; Liu Peng; Min Xinmin; Li, Xi

    2012-01-01

    Due to their unique optical properties, quantum dots (QDs) are rapidly revolutionizing many areas of medicine and biology. Despite the remarkable speed of development of nanoscience, relatively little is known about the interaction of nanoscale objects with organism. In this work, interaction of CdTe QDs coated with mercaptopropanoic acid (MPA), L-cysteine (L-cys), and glutathione (GSH) with bovine serum albumin (BSA) was investigated. Fluorescence (FL), UV–vis absorption, and circular dichroism (CD) spectra methods were used. The Stern-Volmer quenching constant (K sv ) at different temperatures, corresponding thermodynamic parameters (ΔH, ΔG and ΔS), and information of the structural features of BSA were gained. We found that QDs can effectively quench the FL of BSA in a ligand-dependent manner, electrostatic interactions play a major role in the binding reaction, and the nature of quenching is static, resulting in forming QDs-BSA complexes. The CD spectra showed that the secondary and tertiary structure of BSA was changed. This study contributes to a better understanding of the ligand effects on QDs-proteins interactions, which is a critical issue for the applications in vivo. - Highlights: ► The interaction between three thiol-capped QDs and BSA by UV–vis, FL, and CD spectra. ► The bio-effect of CdTe QDs on BSA was a ligand-dependent manner. ► The thermodynamic parameters and the structural features of BSA were gained.

  1. Comparative Interactions of Dihydroquinazolin Derivatives with Human Serum Albumin Observed via Multiple Spectroscopy

    Directory of Open Access Journals (Sweden)

    Yi Wang

    2017-02-01

    Full Text Available The interactions of dihydroquinazolines with human serum albumin (HSA were studied in pH 7.4 aqueous solution via fluorescence, circular dichroism (CD and Fourier transform infrared (FTIR spectroscopic techniques. In this work, 6-chloro-1-(3,3-dimethyl-butanoyl-2(unsubstitutedphenyl-2,3-dihydroquinazolin-4(1H-one (PDQL derivatives were designed and synthesized to study the impact of five similar substituents (methyl, methoxy, cyano, trifluoromethyl and isopropyl on the interactions between PDQL and HSA using a comparative methodology. The results revealed that PDQL quenched the intrinsic fluorescence of HSA through a static quenching process. Displacement experiments with site-specific markers revealed that PDQL binds to HSA at site II (subdomain IIIA and that there may be only one binding site for PDQL on HSA. The thermodynamic parameters indicated that hydrophobic interactions mainly drove the interactions between PDQL and HSA. The substitution using five similar groups in the benzene ring could increase the interactions between PDQL and HSA to some extent through the van der Waals force or hydrogen bond effects in the proper temperature range. Isopropyl substitution could particularly enhance the binding affinity, as observed via comparative studies

  2. The interaction between 4-aminoantipyrine and bovine serum albumin: Multiple spectroscopic and molecular docking investigations

    International Nuclear Information System (INIS)

    Teng Yue; Liu Rutao; Li Chao; Xia Qing; Zhang Pengjun

    2011-01-01

    4-Aminoantipyrine (AAP) is widely used in the pharmaceutical industry, in biochemical experiments and in environmental monitoring. AAP as an aromatic pollutant in the environment poses a great threat to human health. To evaluate the toxicity of AAP at the protein level, the effects of AAP on bovine serum albumin (BSA) were investigated by multiple spectroscopic techniques and molecular modeling. After the inner filter effect was eliminated, the experimental results showed that AAP effectively quenched the intrinsic fluorescence of BSA via static quenching. The number of binding sites, the binding constant, the thermodynamic parameters and binding subdomain were measured, and indicated that AAP could spontaneously bind with BSA on subdomain IIIA through electrostatic forces. Molecular docking results revealed that AAP interacted with the Glu 488 and Glu 502 residues of BSA. Furthermore, the conformation of BSA was demonstrably changed in the presence of AAP. The skeletal structure of BSA loosened, exposing internal hydrophobic aromatic ring amino acids and peptide strands to the solution.

  3. Interaction of Hyperoside with Human Serum Albumin and Effect of Glucose on the Binding

    Directory of Open Access Journals (Sweden)

    Jie Yang

    2014-01-01

    Full Text Available The interaction of hyperoside (Hyp with human serum albumin (HSA and effect of glucose on the binding were studied in simulating physiological condition (pH 7.40. The results suggested that Hyp quenched the endogenous fluorescence of HSA via a static quenching process with the distance of 1.95 nm between Hyp and HSA. Hydrophobic forces played a major role in stabilizing the Hyp-HSA complex. Through synchronous fluorescence monitoring of conformation of HSA, we found that the binding to Hyp can change the microenvironment around tryptophan (Trp residues. Increasing in glucose concentration over a range from 0 to 9 mM decreased the binding ability of HSA to Hyp, implying that increasing in glucose concentration would increase the concentration of free Hyp.

  4. Investigation on the interaction of pyrene with bovine serum albumin using spectroscopic methods.

    Science.gov (United States)

    Xu, Chengbin; Gu, Jiali; Ma, Xiping; Dong, Tian; Meng, Xuelian

    2014-05-05

    This paper was designed to investigate the interaction of pyrene with bovine serum albumin (BSA) under physiological condition by spectroscopic methods. Spectroscopic analysis of the emission quenching revealed that the quenching mechanism of BSA by pyrene was static. The binding sites and constants of pyrene-BSA complex were observed to be 1.20 and 2.63×10(6) L mol(-1) at 298 K, respectively. The enthalpy change (ΔH) and entropy change (ΔS) revealed that van der Waals forces and hydrogen bonds stabilized the pyrene-BSA complex. Energy transfer from tryptophan to pyrene occurred by a FRET (fluorescence resonance energy transfer) mechanism, and the distance (r=2.72 nm) had been determined. The results of synchronous, three-dimensional fluorescence, and circular dichroism spectra showed that the pyrene induced conformational changes of BSA. Copyright © 2014 Elsevier B.V. All rights reserved.

  5. Spectroscopic analysis of the interaction between tetra-(p-sulfoazophenyl-4-aminosulfonyl-substituted aluminum (III phthalocyanines and serum albumins

    Directory of Open Access Journals (Sweden)

    Liqin Zheng

    2017-03-01

    Full Text Available The binding interaction between tetra-(p-sulfoazophenyl-4-aminosulfonyl-substituted aluminum (III phthalocyanine (AlPc, and two-serum albumins (bovine serum albumin (BSA and human serum albumin (HSA has been investigated. AlPc could quench the intrinsic fluorescence of BSA and HSA through a static quenching process. The primary and secondary binding sites of AlPc on BSA were domain I and III of BSA. The primary binding site of AlPc on HSA was domain I, and the secondary binding sites of AlPc on HSA were found at domains I and II. Our results suggest that AlPc readily interact with BSA and HSA implying that the amphiphilic substituents AlPc may contribute to their transportation in the blood.

  6. An interaction of the functionalized closo-borates with albumins: The protein fluorescence quenching and calorimetry study

    Energy Technology Data Exchange (ETDEWEB)

    Losytskyy, Mykhaylo Yu., E-mail: mlosytskyy@gmail.com [Institute of Molecular Biology and Genetics, NASU, 150 Zabolotnogo Street, 03143 Kyiv (Ukraine); Kovalska, Vladyslava B. [Institute of Molecular Biology and Genetics, NASU, 150 Zabolotnogo Street, 03143 Kyiv (Ukraine); Varzatskii, Oleg A. [V. I. Vernadsky Institute of General and Inorganic Chemistry, 32/34 Palladin Avenue, 03080 Kyiv (Ukraine); Kuperman, Marina V. [Institute of Molecular Biology and Genetics, NASU, 150 Zabolotnogo Street, 03143 Kyiv (Ukraine); Potocki, Slawomir; Gumienna-Kontecka, Elzbieta [Faculty of Chemistry, Wroclaw University, 14F. Joliot-Curie Street, 50-383 Wroclaw (Poland); Zhdanov, Andrey P. [Kurnakov Institute of General and Inorganic Chemistry, 31 Leninskii Avenue, 119991 Moscow (Russian Federation); Yarmoluk, Sergiy M. [Institute of Molecular Biology and Genetics, NASU, 150 Zabolotnogo Street, 03143 Kyiv (Ukraine); Voloshin, Yan Z. [Nesmeyanov Institute of Organoelement Compounds, 28 Vavilova Street, 119991 Moscow (Russian Federation); Zhizhin, Konstantin Yu.; Kuznetsov, Nikolai T. [Kurnakov Institute of General and Inorganic Chemistry, 31 Leninskii Avenue, 119991 Moscow (Russian Federation); Elskaya, Anna V. [Institute of Molecular Biology and Genetics, NASU, 150 Zabolotnogo Street, 03143 Kyiv (Ukraine)

    2016-01-15

    An interaction of the boron clusters closo-borates K{sub 2}[B{sub 10}H{sub 10}], K{sub 2}[B{sub 12}H{sub 12}] and their functionalized derivatives with serum proteins human (HSA) and bovine (BSA) albumins and immonoglobulin IgG as well as globular proteins β-lactoglobulin and lysozyme was characterized. The steady state and time resolved protein fluorescence quenching studies point on the binding of the closo-borate arylamine derivatives to serum albumins and discrimination of other proteins. The mechanism of the albumin fluorescence quenching by the closo-borate arylamine derivatives was proposed. The complex formation between albumin and the closo-borate molecules has been confirmed by isothermal titration calorimetry (ITC). The compound (K{sub 2}[B{sub 10}H{sub 10}]) and its arylamine derivative both interact with HSA, have close values of K{sub a} (1.4 and 1.2×10{sup 3} M{sup −1} respectively) and Gibbs energy (−17.9 and −17.5 kJ/mol respectively). However, the arylamine derivative forms complex with the higher guest/host binding ratio (4:1) comparing to the parent closo-borate (2:1). - Highlights: • Complex formation between boron clusters closo-borates and albumins was confirmed. • Functional substituent of closo-borate strongly affects its complex with albumins. • Binding of arylamine closo-borates essentially quench the albumin fluorescence. • Mechanism of tryptophan emission quenching by arylamine closo-borates was proposed.

  7. Investigation of the interaction of naringin palmitate with bovine serum albumin: spectroscopic analysis and molecular docking.

    Directory of Open Access Journals (Sweden)

    Xia Zhang

    Full Text Available BACKGROUND: Bovine serum albumin (BSA contains high affinity binding sites for several endogenous and exogenous compounds and has been used to replace human serum albumin (HSA, as these two compounds share a similar structure. Naringin palmitate is a modified product of naringin that is produced by an acylation reaction with palmitic acid, which is considered to be an effective substance for enhancing naringin lipophilicity. In this study, the interaction of naringin palmitate with BSA was characterised by spectroscopic and molecular docking techniques. METHODOLOGY/PRINCIPAL FINDINGS: The goal of this study was to investigate the interactions between naringin palmitate and BSA under physiological conditions, and differences in naringin and naringin palmitate affinities for BSA were further compared and analysed. The formation of naringin palmitate-BSA was revealed by fluorescence quenching, and the Stern-Volmer quenching constant (KSV was found to decrease with increasing temperature, suggesting that a static quenching mechanism was involved. The changes in enthalpy (ΔH and entropy (ΔS for the interaction were detected at -4.11 ± 0.18 kJ·mol(-1 and -76.59 ± 0.32 J·mol(-1·K(-1, respectively, which indicated that the naringin palmitate-BSA interaction occurred mainly through van der Waals forces and hydrogen bond formation. The negative free energy change (ΔG values of naringin palmitate at different temperatures suggested a spontaneous interaction. Circular dichroism studies revealed that the α-helical content of BSA decreased after interacting with naringin palmitate. Displacement studies suggested that naringin palmitate was partially bound to site I (subdomain IIA of the BSA, which was also substantiated by the molecular docking studies. CONCLUSIONS/SIGNIFICANCE: In conclusion, naringin palmitate was transported by BSA and was easily removed afterwards. As a consequence, an extension of naringin applications for use in food, cosmetic

  8. Comprehensive spectroscopic probing the interaction and conformation impairment of bovine serum albumin (BSA) by herbicide butachlor.

    Science.gov (United States)

    Liu, Xiaoyi; Ling, Zhaoxing; Zhou, Xing; Ahmad, Farooq; Zhou, Ying

    2016-09-01

    Butachlor is an effective herbicide to deal with undesired weeds selectively and is used at high levels in Asian countries. However, its interaction and impairment effect on BSA was still not clear. In this study, we investigated the interaction between butachlor and bovine serum albumin (BSA) by multi-spectroscopic methods including UV absorption, circular dichroism (CD) spectra, Fourier transform infrared (FTIR) spectra and fluorescence spectra under physiological conditions (pH=7.4). The results revealed that there was a static quenching of BSA induced by butachlor stemmed from the formation of complex. Based on thermodynamic data, the interaction of butachlor with BSA was due to happen, and van der Waals force as well as hydrogen bond were the major forces contributed to the interaction. The binding constant Kb and number of binding site of butachlor with BSA were 5.158×10(5) and 1.372 at 303K, respectively. The distance r between donor (BSA) and acceptor (butachlor) was 0.113nm, obtained according to the Förster theory. The results revealed that butachlor induced conformational changes in BSA but the secondary structure of BSA was still retained. In addition, the microenvironment around chromophore residues of BSA, for example, tryptophan, changed as well, resulting from the formation of more hydrogen bonds. Copyright © 2016 Elsevier B.V. All rights reserved.

  9. Spectroscopic study on the interaction between mononaphthalimide spermidine (MINS) and bovine serum albumin (BSA).

    Science.gov (United States)

    Tian, Zhiyong; Zang, Fenglei; Luo, Wen; Zhao, Zhonghua; Wang, Yueqiao; Xu, Xuejun; Wang, Chaojie

    2015-01-01

    The interaction mononaphthalimide spermidine (MINS, 1) and bovine serum albumin (BSA) was studied by UV/vis absorption, fluorescence and circular dichroism spectra (CD) under physiological conditions (pH=7.4). The observed spectral quenching of BSA by compound 1 indicated compound 1 could bind to BSA. Further fluorescent tests revealed that the quenching mechanism of BSA by compound 1 was overall static. Meanwhile, the obtained binding constant and thermodynamic parameters on compound-BSA interaction showed that the type of interaction force of compound 1 and BSA was mainly hydrophobic. The analysis of synchronous, three-dimensional fluorescence and CD showed that compound 1 had weak influence on the conformational changes in BSA. Molecular docking simulation was performed and docking model in silico suggested that the configuration of compound 1 was localized in enzymatic drug site II in BSA. Furthermore, naphthalimide moiety of compound 1 greatly contributed to the hydrophobic interaction between compound 1 and BSA protein, as confirmed by experimental data. Copyright © 2014 Elsevier B.V. All rights reserved.

  10. Interactions of poly(amidoamine) dendrimers with human serum albumin: binding constants and mechanisms.

    Science.gov (United States)

    Giri, Jyotsnendu; Diallo, Mamadou S; Simpson, André J; Liu, Yi; Goddard, William A; Kumar, Rajeev; Woods, Gwen C

    2011-05-24

    The interactions of nanomaterials with plasma proteins have a significant impact on their in vivo transport and fate in biological fluids. This article discusses the binding of human serum albumin (HSA) to poly(amidoamine) [PAMAM] dendrimers. We use protein-coated silica particles to measure the HSA binding constants (K(b)) of a homologous series of 19 PAMAM dendrimers in aqueous solutions at physiological pH (7.4) as a function of dendrimer generation, terminal group, and core chemistry. To gain insight into the mechanisms of HSA binding to PAMAM dendrimers, we combined (1)H NMR, saturation transfer difference (STD) NMR, and NMR diffusion ordered spectroscopy (DOSY) of dendrimer-HSA complexes with atomistic molecular dynamics (MD) simulations of dendrimer conformation in aqueous solutions. The binding measurements show that the HSA binding constants (K(b)) of PAMAM dendrimers depend on dendrimer size and terminal group chemistry. The NMR (1)H and DOSY experiments indicate that the interactions between HSA and PAMAM dendrimers are relatively weak. The (1)H NMR STD experiments and MD simulations suggest that the inner shell protons of the dendrimers groups interact more strongly with HSA proteins. These interactions, which are consistently observed for different dendrimer generations (G0-NH(2)vs G4-NH(2)) and terminal groups (G4-NH(2)vs G4-OH with amidoethanol groups), suggest that PAMAM dendrimers adopt backfolded configurations as they form weak complexes with HSA proteins in aqueous solutions at physiological pH (7.4).

  11. Tuning the solution organization of cationic polymers through interactions with bovine serum albumin.

    Science.gov (United States)

    Papagiannopoulos, Aristeidis; Vlassi, Eleni; Pispas, Stergios; Jafta, Charl J

    2017-07-19

    The interactions of bovine serum albumin (BSA) with aggregates of cationic polymers, i.e. quaternized poly(chloromethyl styrene) chains (QIm-PCMS), in aqueous solutions are investigated using small angle neutron scattering on length scales relevant to the size of BSA. The arrangement of the macromolecular chains within their aggregates is consistent with a blob description of overlapping chains that contain hydrophobic domains. The local conformations depend on the salt content as in typical linear polyelectrolytes. Although the hydrophobic content of the cationic polymers does not cause measurable local morphology differences, the interactions with BSA are enhanced in the case of the not fully quaternized polymer. The secondary structure of BSA is critically compromised by the interaction with the quaternized polymers as the signature of the alpha helix conformation is lost. The complexation with BSA and the resulting enhancement of interchain associations on higher length scales are verified using dynamic light scattering experiments. This study demonstrates the ability to tune the polyelectrolyte/protein interactions and polyelectrolyte chain-chain associations by modifying the hydrophobic content of the polyelectrolytes.

  12. Calorimetric and spectroscopic studies of the interaction between zidovudine and human serum albumin

    Science.gov (United States)

    Pîrnău, Adrian; Mic, Mihaela; Neamţu, Silvia; Floare, Călin G.; Bogdan, Mircea

    2018-02-01

    A quantitative analysis of the interaction between zidovudine (AZT) and human serum albumin (HSA) was achieved using Isothermal titration calorimetry (ITC) in combination with fluorescence and 1H NMR spectroscopy. ITC directly measure the heat during a biomolecular binding event and gave us thermodynamic parameters and the characteristic association constant. By fluorescence quenching, the binding parameters of AZT-HSA interaction was determined and location to binding site I of HSA was confirmed. Via T1 NMR selective relaxation time measurements the drug-protein binding extent was evaluated as dissociation constants Kd and the involvement of azido moiety of zidovudine in molecular complex formation was put in evidence. All three methods indicated a very weak binding interaction. The association constant determined by ITC (3.58 × 102 M- 1) is supported by fluorescence quenching data (2.74 × 102 M- 1). The thermodynamic signature indicates that at least hydrophobic and electrostatic type interactions played a main role in the binding process.

  13. Study on the interaction between promethazine hydrochloride and bovine serum albumin by fluorescence spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    He Lingling [Department of Chemistry, Northeastern University, Shenyang 110004 (China); College of Applied Chemistry, Shenyang University of Chemical Technology, Shenyang 110142 (China); Wang Xin [School of Pharmaceutical Sciences, Liaoning University, Shenyang 110036 (China); Liu Bin [Department of Chemistry, Northeastern University, Shenyang 110004 (China); School of Pharmaceutical Sciences, Liaoning University, Shenyang 110036 (China); Wang Jun [School of Pharmaceutical Sciences, Liaoning University, Shenyang 110036 (China); Sun Yaguang; Gao Enjun [College of Applied Chemistry, Shenyang University of Chemical Technology, Shenyang 110142 (China); Xu Shukun, E-mail: xushukun46@126.co [Department of Chemistry, Northeastern University, Shenyang 110004 (China)

    2011-02-15

    The interaction between promethazine hydrochloride (PMT) and bovine serum albumin (BSA) in vitro was investigated by means of fluorescence spectroscopy and absorption spectroscopy. The fluorescence of BSA was quenched remarkably by PMT and the quenching mechanism was considered as static quenching by forming a complex. The association constants K{sub a} and the number of binding sites n were calculated at different temperatures. The BSA-PMT binding distance was determined to be less than 8 nm, suggesting that energy transfer from BSA to PMT may occur. The thermodynamic parameters of the interaction between PMT and BSA were measured according to the van't Hoff equation. The enthalpy change ({Delta}H) and entropy change ({Delta}S) were calculated to be -23.62 kJ mol{sup -1} and -0.10 J mol{sup -1} K{sup -1}, respectively, which indicated that the interaction of PMT with BSA was driven mainly by van der Waals forces and hydrogen bonds. The binding process was a spontaneous process in which Gibbs free energy change ({Delta}G) was negative. In addition, the results of synchronous fluorescence spectra and three-dimensional fluorescence spectra showed that binding of PMT with BSA can induce conformational changes in BSA.

  14. Interaction of human serum albumin with Fe(III)–deferasirox studied by multispectroscopic methods

    Energy Technology Data Exchange (ETDEWEB)

    Dehghan, Gholamreza, E-mail: dehghan2001d@yahoo.com [Department of Biology, Faculty of Natural Science, University of Tabriz, Tabriz (Iran, Islamic Republic of); Shaghaghi, Masoomeh [Department of Chemistry, Payame Noor University, PO Box 19395-3697 Tehran, I.R. of Iran (Iran, Islamic Republic of); Sattari, Safura [Islamic Azad University, Science and Research Branch, Tehran (Iran, Islamic Republic of); Jouyban, Abolghasem [Drug Applied Research Center and Faculty of Pharmacy, Tabriz University of Medical Sciences, Tabriz 51664 (Iran, Islamic Republic of)

    2014-05-01

    The interaction between the iron complex of deferasirox (Fe(III)–DFX) and human serum albumin (HSA) was studied by fluorescence, UV–vis absorption and circular dichroism (CD) spectroscopy. Binding constants, number of binding sites and binding distance (r) were calculated. Fluorescence data at different temperatures revealed that the fluorescence intensity of HSA is decreased in the presence of Fe(III)–DFX complex, and the fluorescence quenching was the result of the formation of the Fe(III)–DFX–HSA complex, therefore the quenching mechanism was static. The binding constant (K{sub a}) for the interaction was 10{sup 4}, and the number of binding site was obtained ∼1. The thermodynamic parameters including enthalpy (∆H), entropy (∆S) and Gibb's free energy (∆G) changes were calculated according to the van't Hoff equation. These data suggested that hydrophobic interaction was the dominant intermolecular force in stabilizing the complex and the association process was spontaneous. The interaction of HSA with Fe(III)–DFX was also confirmed by UV–vis absorption spectra. The quantitative analysis data of CD spectra showed significant alterations of HSA secondary structure in the presence of Fe(III)–DFX complex in aqueous solution with reduction of α-helices content and increase of β-turn structure. - Highlights: • The interaction between Fe(III)–DFX and (HSA) was studied by multispectroscopic methods. • Fluorescence intensity of HSA is decreased in the presence of Fe(III)–DFX complex through a static quenching procedure. • Thermodynamic data suggested that hydrophobic interaction was the dominant intermolecular force and the association process was spontaneous. • The CD spectra showed significant alterations of HSA secondary structure with reduction of α-helices content and increase of β-turn structure.

  15. Studies of the interaction of CS@ZnS:Mn with bovine serum albumin under illumination

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Li, E-mail: 2476625723@qq.com [Institute of Agricultural Quality Standards and Testing Technology Research, Hubei Academy of Agricultural Science, Wuhan 430064 (China); Xiao, Ling [School of Resource and Environmental Science, Hubei Biomass-Resource Chemistry and Environmental Biotechnology Key Laboratory, Wuhan University, Wuhan 430072 (China)

    2015-09-15

    Highlights: • The interaction and illumination damages of CS@ZnS:Mn D-dots to BSA were studied. • The quenching mechanism of CS@ZnS:Mn D-dots with BSA belongs to dynamic quenching. • The hydrophobic interaction plays a major role; the binding processes are spontaneous. • The FL enhancement of CS@ZnS:Mn D-dots by BSA under UV illumination was observed. • The probable mechanism is mainly a photo-induced free radical procedure. - Abstract: In this study, chitosan coated Mn-doped ZnS quantum dots (CS@ZnS:Mn D-dots) were obtained in aqueous media under ambient pressure. The interaction and illumination damages of CS@ZnS:Mn D-dots with bovine serum albumin (BSA) were studied by means of ultraviolet–visible (UV–vis) and fluorescence (FL) spectra. It was found that the FL of BSA was quenched by CS@ZnS:Mn D-dots. The dominating quenching mechanism of CS@ZnS:Mn D-dots with BSA belongs to dynamic quenching. Hydrophobic interaction plays a major role in the CS@ZnS:Mn–BSA interaction; binding processes are spontaneous. Influencing factors such as illumination time and CS@ZnS:Mn D-dots concentrations were considered. The FL quenching effect of BSA by CS@ZnS:Mn D-dots is enhanced with the increase of illumination time and CS@ZnS:Mn D-dots concentration. The FL enhancement of CS@ZnS:Mn D-dots by BSA under UV illumination was also observed. It was proved that, the interaction of CS@ZnS:Mn D-dots with BSA under UV illumination is mainly a result of a photo-induced free radical procedure. CS@ZnS:Mn D-dots may be used as photosensitizers in photodynamic therapy.

  16. In Vitro Investigation of the Interaction of Tolbutamide and Losartan with Human Serum Albumin in Hyperglycemia States

    Directory of Open Access Journals (Sweden)

    Agnieszka Szkudlarek

    2017-12-01

    Full Text Available Serum albumin is exposed to numerous structural modifications which affect its stability and activity. Glycation is one of the processes leading to the loss of the original properties of the albumin and physiological function disorder. In terms of long lasting states of the hyperglycemia, Advanced Glycation End-products (AGEs are formed. AGEs are responsible for cellular and tissue structure damage that cause the appearance of a number of health consequences and premature aging. The aim of the present study was to analyze the conformational changes of serum albumin by glycation—“fructation”—using multiple spectroscopic techniques, such as absorption (UV-Vis, fluorescence (SFM, circular dichroism (CD and nuclear magnetic resonance (NMR spectroscopy and evaluate of possible alteration of binding and competition between tolbutamide (TB, a first-generation sulfonylurea oral hypoglycemic drug and losartan (LOS, an angiotensin II receptor (AT1 blocker used in hypertension (1st line with a coexisting diabetes in binding to non-glycated (HSA and glycated (gHSAFRC human serum albumin in high-affinity binding sites. The studies allowed us to indicate the structural alterations of human serum albumin as a result of fructose glycation. Changes in binding parameters, such as association ( K a or Stern-Volmer ( K S V constants suggest that glycation increases the affinity of TB and LOS towards albumin and affects interactions between them. The process of albumin glycation influences the pharmacokinetics of drugs, thus monitored pharmacotherapy is reasonable in the case of diabetes and hypertension polypharmacy. This information may lead to the development of more effective drug treatments based on personalized medicine for patients with diabetes. Our studies suggest the validity of monitored polypharmacy of diabetes and coexisting diseases.

  17. Spectroscopic investigation of the interactions of carbofuran and amitrol herbicides with human serum albumin

    Energy Technology Data Exchange (ETDEWEB)

    Tunç, Sibel, E-mail: stunc@akdeniz.edu.tr; Duman, Osman, E-mail: osmanduman@akdeniz.edu.tr; Soylu, İnanç; Kancı Bozoğlan, Bahar

    2014-07-01

    In this study, various spectroscopic techniques including UV absorption, fluorescence and synchronous fluorescence spectroscopy were used to examine the interactions of carbofuran (CF) and amitrol (AMT) herbicides with human serum albumin (HSA). The results of spectroscopic experiments illustrated that CF was bound by HSA, on the other hand there was no interaction between HSA and AMT molecules. In HSA–CF system, static quenching mechanism was responsible for the fluorescence quenching of HSA. The Stern–Volmer constant and binding constant decreased with increasing temperature. This means that an increase in temperature reduces the stability of HSA–CF complex. In HSA–CF system, the number of binding site on protein was found to be one. From the thermodynamic parameters, enthalpy change (ΔH) and entropy change (ΔS) were calculated as −22.30 kJ mol{sup −1} and −10.70 J mol{sup −1} K{sup −1}, respectively, which indicated that the interaction forces between HSA and CF molecules were mainly hydrogen bonding and van der Waals forces. The conformational change in the protein structure was investigated by synchronous fluorescence spectroscopy. According to the results of synchronous fluorescence analysis, there was a change in the protein structure owing to the interaction of CF with HSA. - Highlights: • UV absorption, fluorescence and synchronous fluorescence measurements confirm the formation of HSA–CF complex. • The formation of HSA–CF complex involves both hydrogen bonding and van der Waals forces. • There is no interaction between HSA and AMT molecules. • Binding constants, numbers of binding sites and thermodynamic parameters have been calculated. • The binding of CF to HSA changes the conformational structure of protein.

  18. Interaction of biocompatible natural rosin-based surfactants with human serum albumin: A biophysical study

    Energy Technology Data Exchange (ETDEWEB)

    Ishtikhar, Mohd [Protein Biophysics Laboratory, Interdisciplinary Biotechnology Unit, Aligarh Muslim University, Aligarh 202002 (India); Ali, Mohd Sajid [Surfactant Research Chair, Department of Chemistry, King Saud University, P.O. Box-2455, Riyadh 11451 (Saudi Arabia); Atta, Ayman M. [Surfactant Research Chair, Department of Chemistry, King Saud University, P.O. Box-2455, Riyadh 11451 (Saudi Arabia); Petroleum Application department, Egyptian Petroleum Research Institute, Ahmad Elzomor St., Nasr city, Cairo-11727 (Egypt); Al-Lohedan, H.A. [Surfactant Research Chair, Department of Chemistry, King Saud University, P.O. Box-2455, Riyadh 11451 (Saudi Arabia); Nigam, Lokesh; Subbarao, Naidu [Centre for Computational Biology and Bioinformatics, School of Computational and Integrative Sciences, Jawaharlal Nehru University, New Delhi 110067 (India); Hasan Khan, Rizwan, E-mail: rizwanhkhan@hotmail.com [Protein Biophysics Laboratory, Interdisciplinary Biotechnology Unit, Aligarh Muslim University, Aligarh 202002 (India)

    2015-11-15

    Biophysical insight into interaction of biocompatible rosin-based surfactants with human serum albumin (HSA) was studied at physiological conditions using various spectroscopic, calorimetric and molecular docking approaches. The binding constant (K{sub b}), enthalpy (ΔH{sup 0}), entropy (ΔS{sup 0}) and Gibbs free energy change (ΔG{sup 0}) were calculated by spectroscopic and calorimetric method. We have also calculated the probability of energy transfer by FRET analysis. The circular dichroism study showed that the cationic surfactant QRMAE significantly altered the secondary structure of HSA as compared to the nonionic rosin surfactants. The thermodynamic study was performed by ITC to determine binding constant as well as change in enthalpy of HSA in presence of rosin surfactants. It clearly showed that hydrogen binding and hydrophobic interaction play an important role in the binding of HSA to rosin surfactants. We have also performed molecular docking studies to locate the binding site on HSA and to visualize the mode of interaction. The present study provides a significant insight into HSA–rosin surfactants interaction, which also improves our understanding of the possible effect of rosin surfactants on human health. - Highlights: • RMPEG 750 has the highest Kb, Kq and Ksv value as compared to other rosin surfactants. • The probability of energy transfer from HSA to rosin surfactants was maximum in the case of RMPEG 750. • Cationic surfactant QRMAE significantly altered the secondary structure of the HSA as compared to other rosin surfactants. • Molecular docking and ITC experiment studies, to locate the binding site on HSA and to investigate the mode of interaction.

  19. Study on the interaction between amphiphilic drug and bovine serum albumin: A thermodynamic and spectroscopic description

    Energy Technology Data Exchange (ETDEWEB)

    Rub, Malik Abdul, E-mail: malikrub@gmail.com [Chemistry Department, Faculty of Science, King Abdulaziz University, Jeddah-21589 (Saudi Arabia); Khan, Javed Masood [Interdisciplinary Biotechnology Unit, Aligarh Muslim University, Aligarh 202002 (India); Asiri, Abdullah M. [Chemistry Department, Faculty of Science, King Abdulaziz University, Jeddah-21589 (Saudi Arabia); Center of Excellence for Advanced Materials Research, King Abdulaziz University, Jeddah-21589 (Saudi Arabia); Khan, Rizwan Hasan, E-mail: rizwanhkhan1@gmail.com [Interdisciplinary Biotechnology Unit, Aligarh Muslim University, Aligarh 202002 (India); Kabir-ud-Din [Department of Applied Chemistry, Aligarh Muslim University, Aligarh-202002 (India)

    2014-11-15

    Herein we report the interaction of amphiphilic drug clomipramine hydrochloride (CLP—a tricyclic antidepressant) with bovine serum albumin (BSA) studied by fluorescence, UV–vis, and circular dichroism (CD) spectroscopic techniques. Clomipramine hydrochloride is used to treat a variety of mental health problems. The quenching rate constant (k{sub q}) values, calculated according to the fluorescence data, decrease with increase in temperature indicating the static quenching procedure for the CLP–BSA interaction. The association binding constants (K{sub A}), evaluated at different conditions, and the thermodynamic parameters (free energy, enthalpy and entropy changes) indicate that the hydrophobic forces play a major role in the binding interaction of drug. The interaction of BSA with CLP was further confirmed by UV absorption spectra. Blue shift of position was detected due to the complex formation between the BSA–CLP. The molecular distance, r{sub 0}, between donor (BSA) and acceptor (CLP) was estimated by fluorescence resonance energy transfer (FRET) whose value (4.47 nm) suggests high probability of static quenching interaction. The CD results prove the conformational changes in the BSA on binding with the drug. Thus, the results supply qualitative and quantitative understanding of the binding of BSA to CLP, which is important in understanding their effect as therapeutic agents. - Highlights: • BSA can be considered as a good carrier for transportation of CLP in vivo. • The fluorescence results indicated the presence of static quenching mechanism in the binding process. • CD spectra showed the change in molecular conformation of BSA in the presence of CLP. • The results have applicability in model drug delivery.

  20. Caffeine and sulfadiazine interact differently with human serum albumin: A combined fluorescence and molecular docking study

    Science.gov (United States)

    Islam, Mullah Muhaiminul; Sonu, Vikash K.; Gashnga, Pynsakhiat Miki; Moyon, N. Shaemningwar; Mitra, Sivaprasad

    2016-01-01

    The interaction and binding behavior of the well-known drug sulfadiazine (SDZ) and psychoactive stimulant caffeine (CAF) with human serum albumin (HSA) was monitored by in vitro fluorescence titration and molecular docking calculations under physiological condition. The quenching of protein fluorescence on addition of CAF is due to the formation of protein-drug complex in the ground state; whereas in case of SDZ, the experimental results were explained on the basis of sphere of action model. Although both these compounds bind preferentially in Sudlow's site 1 of the protein, the association constant is approximately two fold higher in case of SDZ (∼4.0 × 104 M-1) in comparison with CAF (∼9.3 × 102 M-1) and correlates well with physico-chemical properties like pKa and lipophilicity of the drugs. Temperature dependent fluorescence study reveals that both SDZ and CAF bind spontaneously with HSA. However, the binding of SDZ with the protein is mainly governed by the hydrophobic forces in contrast with that of CAF; where, the interaction is best explained in terms of electrostatic mechanism. Molecular docking calculation predicts the binding of these drugs in different location of sub-domain IIA in the protein structure.

  1. Interaction and sonodynamic damage activity of acridine red (AD-R) to bovine serum albumin (BSA)

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Dandan; Xie, Jinhui; Wu, Qiong; Fan, Ping; Wang, Jun, E-mail: wangjun888tg@126.com

    2015-04-15

    The sonodynamic therapy (SDT) has become an attractive antitumor treatment method in recent years, but the selection of sonosensitizer, mechanism of damage biomolecule and kind of reactive oxygen species (ROS) generated during sonodynamic process have not been investigated in detail. In this paper, the acridine red (AD-R), as a sonosensitizer, combining with ultrasonic irradiation to damage bovine serum albumin (BSA) was investigated. At first, the interaction of AD-R to BSA molecules in aqueous solution was studied by fluorescence spectroscopy. As judged from the experimental results, the quenching mechanism of BSA fluorescence belongs to a static process. Synchronous fluorescence spectra demonstrate that the binding and damage sites to BSA molecules are mainly on the tryptophan residues. The generation and kind of generated ROS were also estimated by the method of oxidation and extraction photometry. This paper may offer some valuable references for the study of the sonodynamic activity and application of AD-R in SDT for tumor treatment. - Highlights: ●Acridine red (AD-R) is used to study interaction with BSA. ●Spectroscopy is used to study sonodynamic damage activity of AD-R to BSA. ●Generation of ROS caused by AD-R under ultrasonic irradiation was determined.

  2. Surface and micellar properties of Chloroquine Diphosphate and its interactions with surfactants and Human Serum Albumin

    International Nuclear Information System (INIS)

    Usman, Muhammad; Siddiq, Mohammad

    2013-01-01

    Highlights: ► Free energy of adsorption is more negative than free energy of micellization. ► Shifts in UV/Visible spectra in presence of SDS indicated interaction of CLQ with SDS. ► The decrease in fluorescence intensity of HSA by CLQ shows its binding with HSA. -- Abstract: This manuscript addresses the physicochemical behavior of an antimalarial drug Chloroquine Diphosphate (CLQ) as well as its interaction with anionic surfactants and Human Serum Albumin (HSA). Surface tension and specific conductivity were employed to detect the critical micelle concentration (CMC) and thus its surface and thermodynamic parameters were calculated. Solubilization of this drug within micelles of anionic surfactant sodium dodecyl sulfate (SDS) has also been studied. UV/Visible spectroscopy was used to calculate partition coefficient (K x ), free energy of partition and number of drug molecules per micelle. The complexation of drug with HSA at physiological conditions (pH 7.4) has also been analyzed by using UV/Visible and fluorescence spectroscopy. The values of drug-protein binding constant, number of binding sites and free energy of binding were calculated

  3. Interaction of the docetaxel with human serum albumin using optical spectroscopy methods

    Energy Technology Data Exchange (ETDEWEB)

    Cheng Hongxia, E-mail: chenjunbo94@yahoo.com.c [State Key Laboratory of Virology, College of Life Sciences, Center of Nanoscience and Nanotechnology, Wuhan University, Wuhan 430072 (China); Liu Hui; Zhang Yuying [State Key Laboratory of Virology, College of Life Sciences, Center of Nanoscience and Nanotechnology, Wuhan University, Wuhan 430072 (China); Zou Guolin, E-mail: zouguolin@whu.edu.c [State Key Laboratory of Virology, College of Life Sciences, Center of Nanoscience and Nanotechnology, Wuhan University, Wuhan 430072 (China)

    2009-10-15

    Docetaxel is a semi-synthetic product derived from the needles of the European yew. It is an antineoplastic agent belonging to the taxoid family. The interaction between docetaxel and human serum albumin (HSA) has been investigated systematically by the fluorescence quenching technique, synchronous fluorescence spectroscopy, ultraviolet (UV)-vis absorption spectroscopy, circular dichroism (CD) spectroscopy and Fourier transform infrared (FT-IR) under physiological conditions. Our fluorescence data showed that HSA had only one docetaxel binding site and the binding process was a static quenching procedure. According to the Van't Hoff equation, the thermodynamic parameters standard enthalpy (DELTAH{sup 0}) and standard entropy (DELTAS{sup 0}) were calculated to be -41.07 KJ mol{sup -1} and -49.72 J mol{sup -1} K{sup -1}. These results suggested that hydrogen bond was the predominant intermolecular force stabling the docetaxel-HSA complex. The data from the CD, FT-IR and UV-vis spectroscopy supported the change in the secondary structure of protein caused by the interaction of docetaxel with HSA.

  4. Investigation on the interactions of clenbuterol to bovine serum albumin and lysozyme by molecular fluorescence technique.

    Science.gov (United States)

    Bi, Shuyun; Pang, Bo; Wang, Tianjiao; Zhao, Tingting; Yu, Wang

    2014-01-01

    Clenbuterol interacting with bovine serum albumin (BSA) or lysozyme (LYS) in physiological buffer (pH 7.4) was investigated by the fluorescence spectroscopy and UV-vis absorption spectroscopy. The results indicated that clenbuterol quenched the intrinsic fluorescence of BSA and LYS via a static quenching procedure. The binding constants of clenbuterol with BSA and LYS were 1.16×10(3) and 1.49×10(3) L mol(-1) at 291 K. The values of ΔH and ΔS implied that hydrophobic and electrostatic interaction played a major role in stabilizing the complex (clenbuterol-BSA or clenbuterol-LYS). In the presence of Fe2+, Fe3+, Cu2+, Mg2+, Ca2+, or Zn2+, the binding constants of clenbuterol to BSA or LYS had no significant differences. The distances between the donor (BSA or LYS) and acceptor (clenbuterol) were 2.61 and 2.19 nm for clenbuterol-BSA and clenbuterol-LYS respectively. Furthermore, synchronous fluorescence spectrometry was used to analyze the conformational changes of BSA and LYS. Copyright © 2013 Elsevier B.V. All rights reserved.

  5. The investigation of the interaction between piracetam and bovine serum albumin by spectroscopic methods

    Science.gov (United States)

    Guo, Xingjia; Han, Xiaowei; Tong, Jian; Guo, Chuang; Yang, Wenfeng; Zhu, Jifen; Fu, Bing

    2010-03-01

    The interaction between piracetam (OPA) with bovine serum albumin (BSA) has been thoroughly studied by fluorescence quenching technique in combination with UV-vis absorption, Fourier transform infrared (FT-IR), and circular dichroism (CD) spectroscopies under the simulative physiological conditions. The quenching of BSA fluorescence by OPA was found to be a static quenching process. The binding constants ( K a) are 3.014, 2.926, and 2.503 × 10 3 M -1 at 292, 298, and 309 K, respectively. According to the van't Hoff equation, the thermodynamic functions standard enthalpy (Δ H) and standard entropy (Δ S) for the reaction were calculated to be -74.560 kJ mol -1 and -159.380 J mol -1 K -1, which indicated that OPA binds to BSA mainly by hydrogen bonds and van der Waals interactions. The binding distance between BSA and OPA was calculated to be 4.10 nm according to the theory of FÖrster's non-radiation energy transfer. The displacement experiments confirmed that OPA could bind to the site I of BSA. Furthermore, the effects of pH and some common ions on the binding constant were also examined. And the alterations of protein secondary structure in the presence of OPA were observed by the CD and FT-IR spectra.

  6. The investigation of interaction between Thioguanine and human serum albumin by fluorescence and modeling

    Directory of Open Access Journals (Sweden)

    Xin An

    2017-05-01

    Full Text Available The interaction between Thioguanine (6-TG and human serum albumin (HSA under simulative physiological conditions was studied using fluorescence spectroscopy in combination with UV absorption and molecular modeling method. A strong fluorescence quenching reaction of 6-TG to HSA was observed and the quenching mechanism was suggested as static quenching according to the Stern–Volmer equation. The binding constants (K at different temperatures as well as thermodynamic parameters, enthalpy change (ΔH and entropy change (ΔS, were calculated according to relevant fluorescent data and thermodynamic equation. It was indicated that the hydrophobic interaction was a predominant intermolecular force in order to stabilize the copolymer, which was in agreement with the results of molecular modeling study. In addition, the binding distance between 6-TG and the tryptophan residue of HSA was studied according to Föster’s non-radiative energy transfer theory and the effects of common ions on the binding constant of 6-TG-HSA copolymer were also discussed at room temperature.

  7. Spectroscopic Study on the Interaction between Naphthalimide-Polyamine Conjugates and Bovine Serum Albumin (BSA

    Directory of Open Access Journals (Sweden)

    Zhi-Yong Tian

    2015-09-01

    Full Text Available The effect of a naphthalimide pharmacophore coupled with diverse substituents on the interaction between naphthalimide-polyamine conjugates 1–4 and bovine serum albumin (BSA was studied by UV absorption, fluorescence and circular dichroism (CD spectroscopy under physiological conditions (pH = 7.4. The observed spectral quenching of BSA by the compounds indicated that they could bind to BSA. Furthermore, caloric fluorescent tests revealed that the quenching mechanisms of compounds 1–3 were basically static type, but that of compound 4 was closer to a classical type. The Ksv values at room temperature for compound-BSA complexes-1-BSA, 2-BSA, 3-BSA and 4-BSA were 1.438 × 104, 3.190 × 104, 5.700 × 104 and 4.745 × 105, respectively, compared with the value of MINS, 2.863 × 104 at Ex = 280 nm. The obtained quenching constant, binding constant and thermodynamic parameter suggested that the binding between compounds 1–4 with BSA protein, significantly affected by the substituted groups on the naphthalene backbone, was formed by hydrogen bonds, and other principle forces mainly consisting of charged and hydrophobic interactions. Based on results from the analysis of synchronous three-dimensional fluorescence and CD spectra, we can conclude that the interaction between compounds 1–4 and BSA protein has little impact on the BSA conformation. Calculated results obtained from in silico molecular simulation showed that compound 1 did not prefer either enzymatic drug sites I or II over the other. However, DSII in BSA was more beneficial than DSI for the binding between compounds 2–4 and BSA protein. The binding between compounds 1–3 and BSA was hydrophobic in nature, compared with the electrostatic interaction between compound 4 and BSA.

  8. Induction of axial chirality in divanillin by interaction with bovine serum albumin.

    Directory of Open Access Journals (Sweden)

    Diego Venturini

    Full Text Available Vanillin is a plant secondary metabolite and has numerous beneficial health applications. Divanillin is the homodimer of vanillin and used as a taste enhancer compound and also a promissory anticancer drug. Here, divanillin was synthesized and studied in the context of its interaction with bovine serum albumin (BSA. We found that divanillin acquires axial chirality when complexed with BSA. This chiroptical property was demonstrated by a strong induced circular dichroism (ICD signal. In agreement with this finding, the association constant between BSA and divanillin (3.3 x 105 mol-1L was higher compared to its precursor vanillin (7.3 x 104 mol-1L. The ICD signal was used for evaluation of the association constant, demonstration of the reversibility of the interaction and determination of the binding site, revealing that divanillin has preference for Sudlow's site I in BSA. This property was confirmed by displacement of the fluorescent markers warfarin (site I and dansyl-L-proline (site II. Molecular docking simulation confirmed the higher affinity of divanillin to site I. The highest scored conformation obtained by docking (dihedral angle 242° was used for calculation of the circular dichroism spectrum of divanillin using Time-Dependent Density Functional Theory (TDDFT. The theoretical spectrum showed good similarity with the experimental ICD. In summary, we have demonstrated that by interacting with the chiral cavities in BSA, divanillin became a atropos biphenyl, i.e., the free rotation around the single bound that links the aromatic rings was impeded. This phenomenon can be explained considering the interactions of divanillin with amino acid residues in the binding site of the protein. This chiroptical property can be very useful for studying the effects of divanillin in biological systems. Considering the potential pharmacological application of divanillin, these findings will be helpful for researchers interested in the pharmacological

  9. Spectroscopic Study on the Interaction between Naphthalimide-Polyamine Conjugates and Bovine Serum Albumin (BSA).

    Science.gov (United States)

    Tian, Zhi-Yong; Song, Li-Na; Zhao, Yuan; Zang, Feng-Lei; Zhao, Zhong-Hua; Chen, Nan-Hao; Xu, Xue-Jun; Wang, Chao-Jie

    2015-09-11

    The effect of a naphthalimide pharmacophore coupled with diverse substituents on the interaction between naphthalimide-polyamine conjugates 1-4 and bovine serum albumin (BSA) was studied by UV absorption, fluorescence and circular dichroism (CD) spectroscopy under physiological conditions (pH = 7.4). The observed spectral quenching of BSA by the compounds indicated that they could bind to BSA. Furthermore, caloric fluorescent tests revealed that the quenching mechanisms of compounds 1-3 were basically static type, but that of compound 4 was closer to a classical type. The Ksv values at room temperature for compound-BSA complexes-1-BSA, 2-BSA, 3-BSA and 4-BSA were 1.438 × 10⁴, 3.190 × 10⁴, 5.700 × 10⁴ and 4.745 × 10⁵, respectively, compared with the value of MINS, 2.863 × 10⁴ at Ex = 280 nm. The obtained quenching constant, binding constant and thermodynamic parameter suggested that the binding between compounds 1-4 with BSA protein, significantly affected by the substituted groups on the naphthalene backbone, was formed by hydrogen bonds, and other principle forces mainly consisting of charged and hydrophobic interactions. Based on results from the analysis of synchronous three-dimensional fluorescence and CD spectra, we can conclude that the interaction between compounds 1-4 and BSA protein has little impact on the BSA conformation. Calculated results obtained from in silico molecular simulation showed that compound 1 did not prefer either enzymatic drug sites I or II over the other. However, DSII in BSA was more beneficial than DSI for the binding between compounds 2-4 and BSA protein. The binding between compounds 1-3 and BSA was hydrophobic in nature, compared with the electrostatic interaction between compound 4 and BSA.

  10. Thermodynamic Study of the Interaction of Bovine Serum Albumin and Amino Acids with Cellulose Nanocrystals.

    Science.gov (United States)

    Lombardo, Salvatore; Eyley, Samuel; Schütz, Christina; van Gorp, Hans; Rosenfeldt, Sabine; Van den Mooter, Guy; Thielemans, Wim

    2017-06-06

    The interaction of bovine serum albumin (BSA) with sulfated, carboxylated, and pyridinium-grafted cellulose nanocrystals (CNCs) was studied as a function of the degree of substitution by determining the adsorption isotherm and by directly measuring the thermodynamics of interaction. The adsorption of BSA onto positively charged pyridinium-grafted cellulose nanocrystals followed Langmuirian adsorption with the maximum amount of adsorbed protein increasing linearly with increasing degree of substitution. The binding mechanism between the positively charged pyridinum-grafted cellulose nanocrystals and BSA was found to be endothermic and based on charge neutralization. A positive entropy of adsorption associated with an increase of the degree of disorder upon addition of BSA compensated for the unfavorable endothermic enthalpy and enabled formation of pyridinium-g-CNC-BSA complexes. The endothermic enthalpy of adsorption was further found to decrease as a function of increasing degree of substitution. Negatively charged cellulose nanocrystals bearing sulfate and/or carboxylic functionalities were found to not interact significantly with the BSA protein. To investigate in more detail the role of single amino acids in the adsorption of proteins onto cellulose nanocrystals, we also studied the interaction of different types of amino acids with CNCs, i.e., charged (lysine, aspartic acid), aromatic (tryptophan, tyrosine), and polar (serine) amino acids. We found that none of the single amino acids bound with CNCs irrespective of surface charge and that therefore the binding of proteins with CNCs appears to require larger amino acid sequences that induce a greater entropic contribution to stabilize binding. Single amino acids are thus not adsorbed onto cellulose nanocrystals.

  11. Study of the interaction of C60 fullerene with human serum albumin in aqueous solution

    Energy Technology Data Exchange (ETDEWEB)

    Li, Song [Vanderbilt University; Zhao, Xiongce [National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health; Mo, Yiming [ORNL; Cummings, Peter T [ORNL; Heller, William T [ORNL

    2013-01-01

    Concern about the toxicity of engineered nanoparticles, such as the prototypical nanomaterial C60 fullerene, continues to grow. While evidence continues to mount that C60 and its derivatives may pose health hazards, the specific molecular interactions of these particles with biological macromolecules require further investigation. To better understand the interaction of C60 with proteins, the protein human serum albumin (HSA) was studied in solution with C60 at C60:HSA molar ratios ranging from 1:2 to 4:1. HSA is the major protein component of blood plasma and plays a role in a variety of functions, such as the maintenance of blood pH and pressure. The C60-HSA interaction was probed by a combination of circular dichroism (CD) spectroscopy, small-angle neutron scattering (SANS) and atomistic molecular dynamics (MD) simulations to understand C60-driven changes in the structure of HSA in solution. The CD spectroscopy demonstrates that the secondary structure of the protein decreases in -helical content in response to the presence of C60. Similarly, C60 produces subtle changes in the solution conformation of HSA, as evidenced by the SANS data and MD. The data do not indicate that C60 is causing a change in the oligomerization state of the protein. Taken together results demonstrate that C60 interacts with HSA, but it does not strongly perturb the structure of the protein by unfolding it or inducing aggregation, suggesting a mechanism for transporting C60 throughout the body to accumulate in various tissues.

  12. Interaction of bovine serum albumin with a psychotropic drug alprazolam: Physicochemical, photophysical and molecular docking studies

    Energy Technology Data Exchange (ETDEWEB)

    Sarkar, Moumita; Paul, Shiv Shankar; Mukherjea, Kalyan K., E-mail: k_mukherjea@yahoo.com

    2013-10-15

    The interaction between alprazolam (Alp) and bovine serum albumin (BSA) has been investigated under physiological conditions by UV–vis, steady state as well as time-resolved fluorescence, circular dichroism (CD) spectroscopic and molecular docking studies. The binding constant K of Alp to BSA was found to be 1.8×10{sup 5} L mol{sup −1} from absorption data. Fluorometric studies suggested the formation of the Alp–BSA complex, while time-resolved fluorescence studies showed that the binding of Alp by BSA was mainly static and the effective rate constant is found to be 2.33×10{sup 13} L mol{sup −1} s{sup −1}. According to the modified Stern–Volmer equation, the Stern–Volmer quenching constants (K{sub SV}) between Alp and BSA at four different temperatures 295, 303, 308, 313 K were obtained to be 1.19×10{sup 5}, 1.05×10{sup 5}, 0.99×10{sup 5} and 0.90×10{sup 5} L mol{sup −1}, respectively. The change in enthalpy (ΔH) and entropy (ΔS) were calculated to be −11.66 and 57.64 J mol{sup −1} K{sup −1}, respectively, indicating that the interaction was hydrophobic in nature. Site marker competitive experiments suggested that the binding of Alp to BSA primarily took place in sub-domain IIA, whereas the binding distance (r) between Alp and the tryptophan residue of BSA was obtained to be 1.87 nm by Förster's theory of non-radiative energy transfer. The conformational studies by CD spectroscopy showed that the presence of Alp decreased the α-helical content of BSA and induced the unfolding of the polypeptide of the protein. The change in conformation was also supported by excitation–emission matrix spectroscopy (EEMS) studies. The molecular docking experiment supports the above results and effectively proves the binding of Alp to BSA. -- Highlights: • Alprazolam: a benzodiazepine drug with anxiolytic and anticonvulsant properties. • Alprazolam induces conformational change on the native as well as urea denatured BSA. • Alprazolam may

  13. Interaction mode and nanoparticle formation of bovine serum albumin and anthocyanin in three buffer solutions

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Rui; Dong, Xueyan; Song, Lanlan; Jing, Hao, E-mail: hao.haojing@gmail.com

    2014-11-15

    Investigation of interaction mode of bovine serum albumin (BSA) and anthocyanin (ACN) in different solutions will help us understand the interaction mechanism and functional change of bioactive small molecule and biomacromolecule. This study investigated the binding mode, including binding constant, number of binding sites, binding force of BSA and ACN interaction in three buffer solutions of phosphate (PBS), sodium chloride (NaCl), and PBS-NaCl, using fluorescence spectroscopy and synchronous fluorescence spectroscopy. Formation and characteristics of BSA–ACN complex were also investigated using dynamic light scattering (DLS) and transmission electron microscopy (TEM). The results showed that ACN could interact with BSA at both tyrosine (Tyr) and tryptophan (Trp) residues through both hydrogen bonds and van der Waals force, and the same binding mode was seen in dH{sub 2}O and three buffer solutions. The value of binding constant K was decreased as the temperature increased from 298 K to 308 K, and the decreasing degree was in the order of dH{sub 2}O (9.0×10{sup 4})>NaCl (2.64×10{sup 4})/PBS (2.37×10{sup 4})>PBS-NaCl (0.88×10{sup 4}), which was inversely correlated with the ionic strength of the buffer solutions of PBS-NaCl>NaCl>PBS. It indicated that stability of BSA–ACN complex was affected most in dH{sub 2}O than in three buffer solutions. The BSA and ACN interaction led to formation of BSA–ACN nanoparticles. The sizes of BSA–ACN nanoparticles in dH{sub 2}O were smaller than that in three buffer solutions, which correlated with stronger binding force between BSA and ACN in dH{sub 2}O than in three buffer solutions at room temperature (25 °C, 298 K). - Highlights: • We report the influences of four solutions on the BSA–ACN interaction. • We report the relationship between BSA–ACN interaction and particle size of complex. • The stability of BSA–ACN complex was affected most in dH{sub 2}O than in buffer solutions.

  14. Interaction mode and nanoparticle formation of bovine serum albumin and anthocyanin in three buffer solutions

    International Nuclear Information System (INIS)

    Zhou, Rui; Dong, Xueyan; Song, Lanlan; Jing, Hao

    2014-01-01

    Investigation of interaction mode of bovine serum albumin (BSA) and anthocyanin (ACN) in different solutions will help us understand the interaction mechanism and functional change of bioactive small molecule and biomacromolecule. This study investigated the binding mode, including binding constant, number of binding sites, binding force of BSA and ACN interaction in three buffer solutions of phosphate (PBS), sodium chloride (NaCl), and PBS-NaCl, using fluorescence spectroscopy and synchronous fluorescence spectroscopy. Formation and characteristics of BSA–ACN complex were also investigated using dynamic light scattering (DLS) and transmission electron microscopy (TEM). The results showed that ACN could interact with BSA at both tyrosine (Tyr) and tryptophan (Trp) residues through both hydrogen bonds and van der Waals force, and the same binding mode was seen in dH 2 O and three buffer solutions. The value of binding constant K was decreased as the temperature increased from 298 K to 308 K, and the decreasing degree was in the order of dH 2 O (9.0×10 4 )>NaCl (2.64×10 4 )/PBS (2.37×10 4 )>PBS-NaCl (0.88×10 4 ), which was inversely correlated with the ionic strength of the buffer solutions of PBS-NaCl>NaCl>PBS. It indicated that stability of BSA–ACN complex was affected most in dH 2 O than in three buffer solutions. The BSA and ACN interaction led to formation of BSA–ACN nanoparticles. The sizes of BSA–ACN nanoparticles in dH 2 O were smaller than that in three buffer solutions, which correlated with stronger binding force between BSA and ACN in dH 2 O than in three buffer solutions at room temperature (25 °C, 298 K). - Highlights: • We report the influences of four solutions on the BSA–ACN interaction. • We report the relationship between BSA–ACN interaction and particle size of complex. • The stability of BSA–ACN complex was affected most in dH 2 O than in buffer solutions

  15. Spectroscopic investigation of the interaction of water-soluble azocalix[4]arenes with bovine serum albumin.

    Science.gov (United States)

    Fan, Ping; Wan, Lu; Shang, Yunshan; Wang, Jun; Liu, Yulong; Sun, Xiaoyu; Chen, Chen

    2015-02-01

    In this work, three hydrosoluble azocalix[4]arene derivatives, 5-(o-methylphenylazo)-25,26,27-tris(carboxymethoxy)-28-hydroxycalix[4]arene (o-MAC-Calix), 5-(m-methylphenylazo)-25,26,27-tris(carboxymethoxy)-28-hydroxycalix[4]arene (m-MAC-Calix) and 5-(p-methylphenylazo)-25,26,27-tris(carboxymethoxy)-28-hydroxycalix[4]arene (p-MAC-Calix) were synthesized. Their structures were characterized by infrared spectrum (IR), nuclear magnetic resonance spectrum (1H NMR and 13C NMR) and mass spectrum (MS). The interactions between these compounds and bovine serum albumin (BSA) were studied by fluorescence spectroscopy, UV-vis spectrophotometry and circular dichroic spectroscopy. According to experimental results, three azocalix[4]arene derivatives can efficiently bind to BSA molecules and the o-MAC-Calix displays more efficient interactions with BSA molecules than m-MAC-Calix and p-MAC-Calix. Molecular docking showed that the o-MAC-Calix was embedded in the hydrophobic cavity of helical structure of BSA molecular and the tryptophan (Trp) residue of BSA molecular had strong interaction with o-MAC-Calix. The fluorescence quenching of BSA caused by azocalix[4]arene derivatives is attributed to the static quenching process. In addition, the synchronous fluorescence spectroscopy indicates that these azocalix[4]arene derivatives are more accessible to Trp residues of BSA molecules than the tyrosine (Tyr) residues. The circular dichroic spectroscopy further verified the binding of azocalix[4]arene derivatives and BSA. Copyright © 2014 Elsevier Inc. All rights reserved.

  16. Spectroscopic and voltammetric characterizations of the interaction of two local anesthetics with bovine serum albumin

    Energy Technology Data Exchange (ETDEWEB)

    Bi Shuyun, E-mail: sy_bi@sina.co [College of Chemistry, Changchun Normal University, Changchun 130032 (China); Yan Lili; Wang Binbin; Bian Jiangyu [College of Chemistry, Changchun Normal University, Changchun 130032 (China); Sun Yantao [College of Chemistry, Jilin Normal University, Sipin 136000 (China)

    2011-05-15

    The interactions of bovine serum albumin (BSA) with two local anesthetics, procaine hydrochloride (PCH) and tetracaine hydrochloride (TCH) were studied using spectroscopic methods such as fluorescence and ultraviolet visible (UV-vis), and electrochemical techniques including cyclic voltammetry (CV) and differential pulsed stripping voltammetry (DPSV). The results obtained from these techniques turned out that both PCH and TCH could bind to BSA. The binding constants (K{sub A}) and the number of binding sites (n) of the two drugs with BSA at different temperatures were determined, respectively. At 291 K, K{sub A} was found as 2.40x10{sup 4} and 1.42x10{sup 4} L mol{sup -1} and n was 1.03 and 0.99 for PCH-BSA and TCH-BSA, respectively. According to van't Hoff equation, the thermodynamic parameters, {Delta}G, {Delta}H and {Delta}S, were obtained, showing the involvement of hydrophobic and electrostatic force in these interactions. Based on the theory of the Foerster energy transference, the distance between the acceptor (PCH or TCH) and the donor (BSA) were determined as 2.32 and 3.62 nm for PCH and TCH, respectively. The effects of Fe{sup 3+}, Cu{sup 2+}, Mg{sup 2+}, Mn{sup 2+}, Zn{sup 2+} and Ca{sup 2+} on the binding of PCH or TCH to BSA were also evaluated. - Research highlights: Procaine or tetracaine hydrochloride quenching the fluorescence of Trp in BSA was a static quenching process. Synchronous fluorescence was applied to study the structural change of BSA. Binding constant, binding site and binding force were determined. Voltammetry techniques further characterized the nature of the interactions of the two drugs with BSA.

  17. Interaction of ANS with human serum albumin under confinement: Important insights and relevance

    Energy Technology Data Exchange (ETDEWEB)

    Malik, Ashima; Kundu, Jayanta; Karmakar, Sandip; Lai, Sima; Chowdhury, Pramit K., E-mail: pramitc@chemistry.iitd.ac.in

    2015-11-15

    Human serum albumin (HSA) has been extensively studied over the years not only as a model protein but also as an important small molecule carrier with its ability to bind a variety of ligands. This study focuses on the modulation in the conformational disposition of HSA within the confinement of water pools of AOT reverse micelles, and its interactions with 1-anilinonapthelenesulfonate (ANS), the latter serving as a drug moiety. Circular dichroism studies show that while on one hand the incorporation of the protein in the reverse micelles leads to significant distortion in its secondary structure, however, at the same time, addition of ANS leads to a marked increase in helicity of HSA. A combination of FRET studies, time resolved anisotropy measurements and global analyses of temperature dependent spectra reveal little or no significant interaction between HSA and ANS inside the AOT water pools, this being expected, based on the observed distortion of the protein secondary structure on reverse micelle entrapment (the latter resulting in disruption of the binding pockets available to ANS). Taken together our data show possible insights into how HSA releases its bound species (when interacting with membranes or charged confined spaces) and thereby remains a viable drug carrier. - Highlights: • Perturbation of the native structure of HSA in reverse micelles was investigated. • The thermal transition of HSA was quite non-cooperative inside the water pools. • 1-ANS was use to check whether it was binding to HSA inside the water pools. • Our analyses show the HSA subdomain cavities to be perturbed not allowing ANS to bind. • This we propose is a manner that HSA can release its bound molecules.

  18. Synthesis of biological active thiosemicarbazone and characterization of the interaction with human serum albumin

    International Nuclear Information System (INIS)

    Yu, Wangshu; Shi, Lei; Hui, Guangquan; Cui, Fengling

    2013-01-01

    The synthesis of a new biological active reagent, 2-((1,4-dihydroxy)-9,10-anthraquinone) aldehyde thiosemicarbazone (DHAQTS), was designed. The interaction between DHAQTS and HSA was studied by fluorescence spectroscopy in combination with molecular modeling under simulation of physiological conditions. According to the results of fluorescence measurements, the quenching mechanism was suggested to be static. The thermodynamic parameters are calculated by van't Hoff equation, which demonstrated that hydrophobic interactions are the predominant intermolecular forces stabilizing the complex. The number of binding sites (n) was calculated. Through the site marker competitive experiment, DHAQTS was confirmed to be located in site I of HSA. The binding distance r=2.83 nm between the donor HSA and acceptor DHAQTS was obtained according to Förster's non-radiative energy transfer theory. The three-dimensional fluorescence spectral results showed the conformation and microenvironment of HSA changed in the presence of DHAQTS. The effects of common ions on the binding of DHAQTS to HSA were also evaluated. The experimental results were in agreement with the results obtained via a molecular docking study. - Highlights: ► 2-((1,4-dihydroxy)-9,10-anthraquinone)aldehyde thiosemicarbazone (DHAQTS) was synthesized. ► DHAQTS can quench the fluorescence of human serum albumin (HSA) by static quenching mechanism. ► Hydrophobic interactions were the predominant intermolecular forces. ► The competitive experiment was carried out to identify the DHAQTS binding site on HSA. ► Three-dimensional spectra confirmed DHAQTS caused the conformational change of HSA.

  19. Characterizing the interaction between oridonin and bovine serum albumin by a hybrid spectroscopic approach

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Zhen [Department of Chemistry, Shantou University, Shantou 515063 (China); Chen, Junhui, E-mail: chenjupush@126.com [Interventional Oncology and Minimally Invasive Therapies Department, Peking University Shenzhen Hospital, Shenzhen 518036 (China); Wang, Shaobin [The Fourth People' s Hospital of Shenzhen, Shenzhen 518033 (China); Chen, Zhanguang, E-mail: kqlu@stu.edu.cn [Department of Chemistry, Shantou University, Shantou 515063 (China)

    2013-02-15

    Oridonin is an effective anticancer drug which has high potency and low systemic toxicity. In this study, the interaction between oridonin and bovine serum albumin (BSA) was investigated by several spectroscopic approaches for the first time. The binding characteristics of oridonin and BSA were determined by fluorescence emission spectra and resonance light scattering spectra. It is showed that the oridonin quenches the fluorescence of BSA and the static quenching constant K{sub SV} is 1.30 Multiplication-Sign 10{sup 4} L mol{sup -1} at 298 K. Moreover, oridonin and BSA form a 1:1 complex with a binding constant of 0.62 Multiplication-Sign 10{sup 4} L mol{sup -1}. On the other hand, the thermodynamic parameters indicate that the binding process was a spontaneous molecular interaction procedure, in which hydrophobic forces played a major role. The structure analysis indicates that oridonin binding results in an increased hydrophobicity around the tryptophan residues of BSA. Additionally, as shown by the UV-vis absorption, synchronous fluorescence and three-dimensional fluorescence results, oridonin could lead to conformational and some microenvironmental changes of BSA. The work provides accurate and full basic data for clarifying the binding mechanism of oridonin with BSA in vitro and is helpful for understanding its effect on protein function during its transportation and distribution in blood. - Highlights: Black-Right-Pointing-Pointer Interaction between oridonin and BSA was evaluated by multi-spectroscopic methods. Black-Right-Pointing-Pointer Binding constant, number of binding sites and thermodynamic parameters were calculated. Black-Right-Pointing-Pointer Oridonin binds to Subdomain II site in BSA and form a 1:1 complex with it. Black-Right-Pointing-Pointer Oridonin-BSA complex is stabilized mainly by hydrophobic force. Black-Right-Pointing-Pointer Oridonin binding induces conformational and microenvironmental changes in BSA.

  20. Binding interaction of phosphorus heterocycles with bovine serum albumin: A biochemical study

    Directory of Open Access Journals (Sweden)

    Swarup Roy

    2017-02-01

    Full Text Available Interaction between bovine serum albumin (BSA and phosphorus heterocycles (PHs was studied using multi-spectroscopic techniques. The results indicated the high binding affinity of PHs to BSA as it quenches the intrinsic fluorescence of BSA. The experimental data suggested the fluorescence quenching mechanism between PHs and BSA as a dynamic quenching. From the UV–vis studies, the apparent association constant (Kapp was found to be 9.25×102, 1.27×104 and 9.01×102 L/mol for the interaction of BSA with PH-1, PH-2 and PH-3 respectively. According to the Förster's non-radiation energy transfer (FRET theory, the binding distances between BSA and PHs were calculated. The binding distances (r of PH-1, PH-2 and PH-3 were found to be 2.86, 3.03, and 5.12 nm, respectively, indicating energy transfer occurs between BSA and PHs. The binding constants of the PHs obtained from the fluorescence quenching data were found to be decreased with increase of temperature. The negative values of the thermodynamic parameters ΔH, ΔS and ΔG at different temperatures revealed that the binding process is spontaneous; hydrogen bonds and van der Waals interaction were the main force to stabilize the complex. The microenvironment of the protein-binding site was studied by synchronous fluorescence and circular dichroism (CD techniques and data indicated that the conformation of BSA changed in the presence of PHs. Finally, we studied the BSA-PHs docking using Autodock and results suggest that PHs is located in the cleft between the domains of BSA.

  1. Study of the interaction between fluoxetine hydrochloride and bovine serum albumin in the imitated physiological conditions by multi-spectroscopic methods

    Energy Technology Data Exchange (ETDEWEB)

    Katrahalli, Umesha [Department of Chemistry, Karnatak University, Dharwad 580 003 (India); Jaldappagari, Seetharamappa, E-mail: j_seetharam@rediffmail.co [Department of Chemistry, Karnatak University, Dharwad 580 003 (India); Kalanur, Shankara S. [Department of Chemistry, Karnatak University, Dharwad 580 003 (India)

    2010-02-15

    The mechanism of interaction of an antidepressant, fluoxetine hydrochloride (FLX) with bovine serum albumin (BSA) has been studied by different spectroscopic techniques under physiological conditions. FLX was found to quench the intrinsic fluorescence of protein by static quenching mechanism. The binding constant 'K' was found to be 7.06x10{sup 3} M{sup -1} at 296 K. The value of 'n' close to unity revealed that the BSA has a single class of binding site for FLX. Based on thermodynamic parameters, hydrogen bonding and van der Waals forces were proposed to operate between BSA and FLX. The change in conformation of protein was noticed upon its interaction with the drug. From displacement studies it was concluded that the FLX bound to protein at site I. The effects of various common metals ions on the binding were also investigated.

  2. Molecular interaction and energy transfer between human serum albumin and bioactive component Aloe dihydrocoumarin

    Science.gov (United States)

    Zhang, Xiu-Feng; Xie, Ling; Liu, Yang; Xiang, Jun-Feng; Li, Lin; Tang, Ya-Lin

    2008-10-01

    Aloe dihydrocoumarin is an antioxidant and a candidate of immunomodulatory drug on the immune system and can balance physiological reactive oxygen species (ROS) levels which may be useful to maintain homeostasis. In order to explore the mechanism of drug action at a molecular level, the binding of Aloe dihydrocoumarin with human serum albumin (HSA) has been investigated by fluorescence, ultraviolet (UV), circular dichroism (CD) and Fourier transform infrared (FT-IR) spectroscopy, fluorescence dynamics, and molecular dynamic docking for the first time. We observed a quenching of fluorescence of HSA in the presence of Aloe dihydrocoumarin and also analyzed the quenching results using the Stern-Volmer equation and obtained high affinity binding to HSA. A Förster type fluorescence resonance energy transfer mechanism is involved in this quenching of Trp fluorescence by Aloe dihydrocoumarin. From the CD and FT-IR results, it is apparent that the interaction of Aloe dihydrocoumarin with HSA causes a conformational change of the protein, with the loss of α-helix stability and the gain of β-sheet and β-turn content. Data obtained by fluorescence spectroscopy, fluorescence dynamics, CD, and FT-IR experiments along with the docking studies suggest that Aloe dihydrocoumarin binds to residues located in subdomain IIA of HSA.

  3. Investigation of Interaction Between Ozagrel and Human Serum Albumin by Spectroscopic and Electrochemical Methods

    Science.gov (United States)

    Li, S.; Wang, Li; Hao, J.; Wang, L.; Tong, Y.-J.; Fu, Z.-Q.; Zhang, A.-P.

    2017-01-01

    The interaction between ozagrel and human serum albumin (HSA) was investigated by fl uorescence spectroscopy, UV-Vis absorption spectroscopy, cyclic voltammetry (CV), differential pulse voltammetry (DPV), and Fourier transform infrared spectroscopy (FTIR) under simulative physiological conditions. The results of CV, DPV and fl uorescence titration revealed that ozagrel bound to HSA. The enthalpy change (ΔH) and the entropy change (ΔS) were derived to be positive values, indicating that the hydrophobic force played the main role in the binding of ozagrel with HSA. The binding distance between ozagrel and HSA was 1.75 nm. Upon binding with ozagrel, the conformation and the secondary structure of HSA molecules were changed. The percentage of α-helix and β-sheet structures decreased by 7.25% and 4.58%, respectively, while the percentage of a β-turn structure increased by 2.67%. The effect of common ions on the binding of ozagrel with HSA was also examined. This study will give an insight into the evaluation of the drug's stabi-lity during transport and its releasing effi ciency at the target site under simulative physiological conditions.

  4. Spectroscopic and calorimetric studies of interaction of methimazole with human serum albumin

    Energy Technology Data Exchange (ETDEWEB)

    Afrin, Sadaf [Department of Chemistry, Aligarh Muslim University, Aligarh 202002, Uttar Pradesh (India); Riyazuddeen, E-mail: rz1@rediffmail.com [Department of Chemistry, Aligarh Muslim University, Aligarh 202002, Uttar Pradesh (India); Rabbani, Gulam; Khan, Rizwan Hasan [Interdisciplinary Biotechnology Unit, Aligarh Muslim University, Aligarh 202002, Uttar Pradesh (India)

    2014-07-01

    The interaction of the anti-thyroid drug, 2-mercapto 1-methylimidazole (methimazole) with human serum albumin (HSA) has been examined by fluorescence and isothermal titration calorimetry (ITC) techniques. Fluorescence results indicate that in case of HSA–drug complex the quenching of fluorescence intensity is at 340 nm. The methimazole has an ability to quench the intrinsic fluorescence of HSA tryptophan through a static quenching procedure. The binding constant has been determined using Stern–Volmer modified equation and energy transfer mechanisms of quenching are discussed. The ΔG°, ΔH°, and ΔS° values are also calculated by ITC measurements. The experimental spectroscopic and thermodynamic parameters have been used for understanding the binding mechanism of anti-thyroid drug with HSA. - Highlights: • The binding of methimazole to HSA quenches the intrinsic fluorescence of tryptophan. • The negative ΔG° value suggests the binding of methimazole with HSA is spontaneous. • The main contribution to ΔG° arises from the ΔS° rather than from ΔH°, so hydrophobic forces most likely play a major role in the binding of methimazole to HSA.

  5. The interaction of plant-growth regulators with serum albumin: molecular modeling and spectroscopic methods.

    Science.gov (United States)

    Dong, Sheying; Li, Zhiqin; Shi, Ling; Huang, Guiqi; Chen, Shuangli; Huang, Tinglin

    2014-05-01

    The affinity between two plant-growth regulators (PGRs) and human serum albumin (HSA) was investigated by molecular modeling techniques and spectroscopic methods. The results of molecular modeling simulations revealed that paclobutrazol (PAC) could bind on both site I and site II in HSA where the interaction was easier, while uniconazole (UNI) could not bind with HSA. Furthermore, the results of fluorescence spectroscopy, three-dimensional (3D) fluorescence spectroscopy and circular dichroism (CD) spectroscopy suggested that PAC had a strong ability to quench the intrinsic fluorescence of HSA. The binding affinity (Kb) and the amounts of binding sites (n) between PAC and HSA at 291 K were estimated as 2.37×10(5) mol L(-1) and 1, respectively, which confirm that PAC mainly binds on site II of HSA. An apparent distance between the Trp214 and PAC was 4.41 nm. Additionally, the binding of PAC induced the conformational changes of disulfide bridges of HSA with the decrease of α-helix content. These studies provide more information on the potential toxicological effects and environmental risk assessment of PGRs. Copyright © 2014 Elsevier Ltd. All rights reserved.

  6. Thermodynamics of the interaction of the food additive tartrazine with serum albumins: a microcalorimetric investigation.

    Science.gov (United States)

    Basu, Anirban; Kumar, Gopinatha Suresh

    2015-05-15

    The thermodynamics of the interaction of the food colourant tartrazine with two homologous serum proteins, HSA and BSA, were investigated, employing microcalorimetric techniques. At T=298.15K the equilibrium constants for the tartrazine-BSA and HSA complexation process were evaluated to be (1.92 ± 0.05) × 10(5)M(-1) and (1.04 ± 0.05) × 10(5)M(-1), respectively. The binding was driven by a large negative standard molar enthalpic contribution. The binding was dominated essentially by non-polyelectrolytic forces which remained largely invariant at all salt concentrations. The polyelectrolytic contribution was weak at all salt concentrations and accounted for only 6-18% of the total standard molar Gibbs energy change in the salt concentration range 10-50mM. The negative standard molar heat capacity values, in conjunction with the enthalpy-entropy compensation phenomenon observed, established the involvement of dominant hydrophobic forces in the complexation process. Tartrazine enhanced the stability of both serum albumins against thermal denaturation. Copyright © 2014 Elsevier Ltd. All rights reserved.

  7. Comparison of the interaction between three anthocyanins and human serum albumins by spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Tang, Lin, E-mail: tanglin@sdnu.edu.cn; Zuo, Huijun; Shu, Li

    2014-09-15

    Anthocyanin is an important kind of water-soluble pigment existing widely in plants, and has various health benefits to human body. The number and location of the hydroxyl groups of the parent nucleus of Anthocyanins have significant effects on their activities. This research employed different spectroscopic methods (i.e. fluorescence spectroscopy, UV–vis absorbance, three-dimensional fluorescence spectra and circular dichroism (CD)) to investigate the mutual interactions between three differently substituted B-ring hydroxyl groups (Pelargonidin-3-O-glucoside, P3G; Cyanidin-3-O-glucoside, C3G and Delphinidin-3-O-glucoside, D3G) and human serum albumin (HSA) under physiological pH conditions. The calculated thermodynamic parameters and the spectrum showed that P3G, C3G and D3G could result in quenching of the intrinsic fluorescence. The comparison result of the strength of comprehensive binding parameter Y (i.e. Y=lg( K{sub a}×E×n/r)), which was used to reflect the extent of interaction of Anthocyanin–HSA system, was Y{sub D3G}>Y{sub C3G}>Y{sub P3G}. Moreover, the secondary structure of HSA was changed in the presence of P3G/C3G/D3G. The α-helix percentage of P3G–HSA increased while that of C3G/D3G–HSA decreased. Overall, these results showed that the number of B-ring –OH in each molecule played an important role in the interaction of these anthocyanins with HSA. - Highlights: • Study the interactions between three differently structured anthocyanins and HSA. • The order of binding parameter Y [Y=lg(K{sub a}×E×n/r)] as Delphinidin>Cyanidin>Pelargonidin. • Increase in the number of B-ring –OH may enhance the binding affinity for HSA. • HSA secondary structural changes occurred due to these interactions. • The number of B-ring –OH in each molecule played an important role in the interaction.

  8. Size-dependent interaction of silica nanoparticles with lysozyme and bovine serum albumin proteins

    Science.gov (United States)

    Yadav, Indresh; Aswal, Vinod K.; Kohlbrecher, Joachim

    2016-05-01

    The interaction of three different sized (diameter 10, 18, and 28 nm) anionic silica nanoparticles with two model proteins—cationic lysozyme [molecular weight (MW) 14.7 kDa)] and anionic bovine serum albumin (BSA) (MW 66.4 kDa) has been studied by UV-vis spectroscopy, dynamic light scattering (DLS), and small-angle neutron scattering (SANS). The adsorption behavior of proteins on the nanoparticles, measured by UV-vis spectroscopy, is found to be very different for lysozyme and BSA. Lysozyme adsorbs strongly on the nanoparticles and shows exponential behavior as a function of lysozyme concentration irrespective of the nanoparticle size. The total amount of adsorbed lysozyme, as governed by the surface-to-volume ratio, increases on lowering the size of the nanoparticles for a fixed volume fraction of the nanoparticles. On the other hand, BSA does not show any adsorption for all the different sizes of the nanoparticles. Despite having different interactions, both proteins induce similar phase behavior where the nanoparticle-protein system transforms from one phase (clear) to two phase (turbid) as a function of protein concentration. The phase behavior is modified towards the lower concentrations for both proteins with increasing the nanoparticle size. DLS suggests that the phase behavior arises as a result of the nanoparticles' aggregation on the addition of proteins. The size-dependent modifications in the interaction potential, responsible for the phase behavior, have been determined by SANS data as modeled using the two-Yukawa potential accounting for the repulsive and attractive interactions in the systems. The protein-induced interaction between the nanoparticles is found to be short-range attraction for lysozyme and long-range attraction for BSA. The magnitude of attractive interaction irrespective of protein type is enhanced with increase in the size of the nanoparticles. The total (attractive+repulsive) potential leading to two-phase formation is found to be

  9. Study on the interaction of catechins with human serum albumin using spectroscopic and electrophoretic techniques

    Science.gov (United States)

    Trnková, Lucie; Boušová, Iva; Staňková, Veronika; Dršata, Jaroslav

    2011-01-01

    The interaction between eight naturally occurring flavanols (catechin, epicatechin, gallocatechin, epigallocatechin, catechin gallate, epicatechin gallate, gallocatechin gallate, and epigallocatechin gallate) and human serum albumin (HSA) has been investigated by spectroscopic (fluorescence quenching and UV-Vis absorption) and electrophoretic (native and SDS PAGE) techniques under simulated physiological conditions (pH 7.40, 37 °C). The spectroscopic results confirmed the complex formation for the tested systems. The binding constants and the number of binding sites were obtained by analysis of fluorescence data. The strongest binding affinity to HSA was found for epicatechin gallate and decreased in the order epicatechin gallate ⩾ catechin gallate > epigallocatechin gallate > gallocatechin gallate ≫ epicatechin ⩾ catechin > gallocatechin ⩾ epigallocatechin. All free energy changes possessed negative sign indicating the spontaneity of catechin-HSA systems formation. The binding distances between the donor (HSA) and the acceptors (catechins) estimated by the Förster theory revealed that non-radiation energy transfer from HSA to catechins occurred with high possibility. According to results obtained by native PAGE, the galloylated catechins increased the electrophoretic mobility of HSA, which indicated the change in the molecular charge of HSA, whilst the non-galloylated catechins caused no changes. The ability of aggregation and cross-linking of tested catechins with HSA was not proved by SDS-PAGE. The relationship between the structure characteristics of all tested catechins (e.g. presence of the galloyl moiety on the C-ring, the number of hydroxyl groups on the B-ring, and the spatial arrangement of the substituents on the C-ring) and their binding properties to HSA is discussed. The presented study contributes to the current knowledge in the area of protein-ligand binding, particularly catechin-HSA interactions.

  10. Spectroscopic and molecular docking techniques study of the interaction between oxymetholone and human serum albumin

    Energy Technology Data Exchange (ETDEWEB)

    Madrakian, Tayyebeh, E-mail: madrakian@basu.ac.ir; Bagheri, Habibollah; Afkhami, Abbas; Soleimani, Mohammad

    2014-11-15

    In this study, the binding of oxymetholone (OXM), a doping drug, to human serum albumin (HSA) was explored at pH 7.40 by spectroscopic methods including spectrofluorimetry, three dimensional excitation–emission matrix (3D EEM), UV–vis absorption, resonance rayleigh scattering (RRS) and molecular docking. The fluorescence results showed that there was a considerable quenching of the intrinsic fluorescence of HSA upon binding to OXM by static quenching mechanism. The Stern–Volmer quenching constants (K{sub SV}) between OXM and HSA at three different temperatures 295, 303, 308 K, were obtained as 4.63×10{sup 4}, 3.05×10{sup 4} and 1.49×10{sup 4} L mol{sup −1}, respectively. Furthermore this interaction was confirmed by UV–vis spectrophotometric and RRS techniques. The binding site number, n, apparent binding constant, K{sub b}, and corresponding thermodynamic parameters (ΔS, ΔH and ΔG) were measured at different temperatures. The Van der Waals and hydrogen-bond forces were found to stabilize OXM–HSA complex. The distance (r) between the donor and acceptor was obtained from Förster's theory of fluorescence resonance energy transfer (FRET) and found to be 1.67 nm. The 3D EEM showed that OXM slightly changes the secondary structure of HSA. Furthermore, the molecular docking was employed for identification of drug binding sites and interaction of OXM with amino acid residues. - Highlights: • The binding of OXM as a doping drug with HSA was studied by different techniques. • The binding constant of HSA–OXM was calculated. • The binding site of OXM on HSA was characterized with molecular docking. • The thermodynamic parameters were calculated according to fluorescence technique.

  11. Spectroscopic analysis on the binding interaction of biologically active pyrimidine derivative with bovine serum albumin

    Directory of Open Access Journals (Sweden)

    Vishwas D. Suryawanshi

    2016-02-01

    Full Text Available A biologically active antibacterial reagent, 2–amino-6-hydroxy–4–(4-N, N-dimethylaminophenyl-pyrimidine-5-carbonitrile (AHDMAPPC, was synthesized. It was employed to investigate the binding interaction with the bovine serum albumin (BSA in detail using different spectroscopic methods. It exhibited antibacterial activity against Escherichia coli and Staphylococcus aureus which are common food poisoning bacteria. The experimental results showed that the fluorescence quenching of model carrier protein BSA by AHDMAPPC was due to static quenching. The site binding constants and number of binding sites (n≈1 were determined at three different temperatures based on fluorescence quenching results. The thermodynamic parameters, enthalpy change (ΔH, free energy (ΔG and entropy change (ΔS for the reaction were calculated to be 15.15 kJ/mol, –36.11 kJ/mol and 51.26 J/mol K according to van't Hoff equation, respectively. The results indicated that the reaction was an endothermic and spontaneous process, and hydrophobic interactions played a major role in the binding between drug and BSA. The distance between donor and acceptor is 2.79 nm according to Förster's theory. The alterations of the BSA secondary structure in the presence of AHDMAPPC were confirmed by UV–visible, synchronous fluorescence, circular dichroism (CD and three-dimensional fluorescence spectra. All these results indicated that AHDMAPPC can bind to BSA and be effectively transported and eliminated in the body. It can be a useful guideline for further drug design.

  12. Spectroscopic Investigations of the Binding Interaction of a New Indanedione Derivative with Human and Bovine Serum Albumins

    Directory of Open Access Journals (Sweden)

    Mihaela Hillebrand

    2009-04-01

    Full Text Available Binding of a newly synthesized indanedione derivative, 2-(2-hydroxy-3-ethoxybenzylidene-1,3-indanedione (HEBID, to human and bovine serum albumins (HSA and BSA, under simulated physiological conditions was monitored by fluorescence spectroscopy. The binding parameters (binding constants and number of binding sites and quenching constants were determined according to literature models. The quenching mechanism was assigned to a Förster non-radiative energy transfer due to the HEBID-SA complex formation. A slightly increased affinity of HEBID for HSA was found, while the number of binding sites is approximately one for both albumins. The molecular distance between donor (albumin and acceptor (HEBID and the energy transfer efficiency were estimated, in the view of Förster’s theory. The effect of HEBID on the protein conformation was investigated using circular dichroism and synchronous fluorescence spectroscopies. The results revealed partial unfolding in the albumins upon interaction, as well as changes in the local polarity around the tryptophan residues

  13. Probing the interaction of a new synthesized CdTe quantum dots with human serum albumin and bovine serum albumin by spectroscopic methods

    International Nuclear Information System (INIS)

    Bardajee, Ghasem Rezanejade; Hooshyar, Zari

    2016-01-01

    A novel CdTe quantum dots (QDs) were prepared in aqueous phase via a facile method. At first, poly (acrylic amide) grafted onto sodium alginate (PAAm-g-SA) were successfully synthesized and then TGA capped CdTe QDs (CdTe-TGA QDs) were embed into it. The prepared CdTe-PAAm-g-SA QDs were optimized and characterized by transmission electron microscopy (TEM), thermo-gravimetric (TG) analysis, Fourier transform infrared (FT-IR), UV–vis and fluorescence spectroscopy. The characterization results indicated that CdTe-TGA QDs, with particles size of 2.90 nm, were uniformly dispersed on the chains of PAAm-g-SA biopolymer. CdTe-PAAm-g-SA QDs also exhibited excellent UV–vis absorption and high fluorescence intensity. To explore biological behavior of CdTe-PAAm-g-SA QDs, the interactions between CdTe-PAAm-g-SA QDs and human serum albumin (HSA) (or bovine serum albumin (BSA)) were investigated by cyclic voltammetry, FT-IR, UV–vis, and fluorescence spectroscopic. The results confirmed the formation of CdTe-PAAm-g-SA QDs-HSA (or BSA) complex with high binding affinities. The thermodynamic parameters (ΔG < 0, ΔH < 0 and ΔS < 0) were indicated that binding reaction was spontaneous and van der Waals interactions and hydrogen-bond interactions played a major role in stabilizing the CdTe-PAAm-g-SA QDs-HSA (or BSA) complexes. The binding distance between CdTe-PAAm-g-SA QDs and HSA (or BSA)) was calculated about 1.37 nm and 1.27 nm, respectively, according to Forster non-radiative energy transfer theory (FRET). Analyzing FT-IR spectra showed that the formation of QDs-HSA and QDs-BSA complexes led to conformational changes of the HSA and BSA proteins. All these experimental results clarified the effective transportation and elimination of CdTe-PAAm-g-SA QDs in the body by binding to HSA and BSA, which could be a useful guideline for the estimation of QDs as a drug carrier. - Highlights: • The CdTe quantum dots coated with polyacrylamide grafted onto sodium alginate. • The

  14. Probing the interaction of a new synthesized CdTe quantum dots with human serum albumin and bovine serum albumin by spectroscopic methods

    Energy Technology Data Exchange (ETDEWEB)

    Bardajee, Ghasem Rezanejade, E-mail: rezanejad@pnu.ac.ir; Hooshyar, Zari

    2016-05-01

    A novel CdTe quantum dots (QDs) were prepared in aqueous phase via a facile method. At first, poly (acrylic amide) grafted onto sodium alginate (PAAm-g-SA) were successfully synthesized and then TGA capped CdTe QDs (CdTe-TGA QDs) were embed into it. The prepared CdTe-PAAm-g-SA QDs were optimized and characterized by transmission electron microscopy (TEM), thermo-gravimetric (TG) analysis, Fourier transform infrared (FT-IR), UV–vis and fluorescence spectroscopy. The characterization results indicated that CdTe-TGA QDs, with particles size of 2.90 nm, were uniformly dispersed on the chains of PAAm-g-SA biopolymer. CdTe-PAAm-g-SA QDs also exhibited excellent UV–vis absorption and high fluorescence intensity. To explore biological behavior of CdTe-PAAm-g-SA QDs, the interactions between CdTe-PAAm-g-SA QDs and human serum albumin (HSA) (or bovine serum albumin (BSA)) were investigated by cyclic voltammetry, FT-IR, UV–vis, and fluorescence spectroscopic. The results confirmed the formation of CdTe-PAAm-g-SA QDs-HSA (or BSA) complex with high binding affinities. The thermodynamic parameters (ΔG < 0, ΔH < 0 and ΔS < 0) were indicated that binding reaction was spontaneous and van der Waals interactions and hydrogen-bond interactions played a major role in stabilizing the CdTe-PAAm-g-SA QDs-HSA (or BSA) complexes. The binding distance between CdTe-PAAm-g-SA QDs and HSA (or BSA)) was calculated about 1.37 nm and 1.27 nm, respectively, according to Forster non-radiative energy transfer theory (FRET). Analyzing FT-IR spectra showed that the formation of QDs-HSA and QDs-BSA complexes led to conformational changes of the HSA and BSA proteins. All these experimental results clarified the effective transportation and elimination of CdTe-PAAm-g-SA QDs in the body by binding to HSA and BSA, which could be a useful guideline for the estimation of QDs as a drug carrier. - Highlights: • The CdTe quantum dots coated with polyacrylamide grafted onto sodium alginate. • The

  15. Investigation of the interaction between isomeric derivatives and human serum albumin by fluorescence spectroscopy and molecular modeling

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Ruiyong, E-mail: wangry@zzu.edu.cn; Dou, Huanjing; Yin, Yujing; Xie, Yuanzhe; Sun, Li; Liu, Chunmei; Dong, Jingjing; Huang, Gang; Zhu, Yanyan; Song, Chuanjun, E-mail: chjsong@zzu.edu.cn; Chang, Junbiao, E-mail: changjunbiao@zzu.edu.cn

    2014-10-15

    In this paper, we have synthesized 9H-pyrrolo[1,2-a]indol-9-ones and the isomeric indeno[2,1-b]pyrrol-8-ones. The interactions of human serum albumin with series of isomeric derivatives have been studied by spectrophotometric methods. Results show the intrinsic fluorescence is quenched by the derivatives with a static quenching procedure. The thermodynamics parameters indicate that van der Waals forces and hydrogen bonds play a major role in the interactions. The results of synchronous fluorescence spectra demonstrate that the microenvironments of Trp residue of human serum albumin are disturbed by most derivatives. Thermodynamic results showed that the 9H-pyrrolo[1,2-a]indol-9-ones are stronger quenchers and bind to human serum albumin with the higher affinity than isomeric indeno[2,1-b]pyrrol-8-ones. The influence of molecular structure on the binding aspects has been investigated. - Highlights: • The interactions between isomeric derivatives and HSA have been investigated. • Results reveal that 9H-pyrrolo[1,2-a]indol-9-ones are stronger quenchers for HSA. • Hydrogen bonds and van der Waals forces play major role in the binding process. • The influence of molecular structure on the binding aspects has been investigated. • The binding study was also modeled by molecular docking.

  16. Spectrofluorimetric study on the interaction between antimicrobial drug sulfamethazine and bovine serum albumin

    Energy Technology Data Exchange (ETDEWEB)

    Dawoud Bani-Yaseen, Abdulilah, E-mail: aayaseen@yahoo.co [Department of Chemistry, Faculty of Science, Taibah University, Al-MAdinah Al-Munawarah P.O. Box 30002 (Saudi Arabia)

    2011-05-15

    The interaction between the antimicrobial drug sulfamethazine (STM) and bovine serum albumin (BSA) has been studied using steady state and synchronous fluorescence spectroscopy. Fluorescence emission data revealed that BSA (2x10{sup -6} M) fluorescence was statically quenched by STM at various concentrations, which implies that STM-BSA complex has been formed. The fluorescence emission data was analyzed via applying the Stern-Volmer analysis in combination with thermodynamic investigation, where obtained results revealed that quenching is static with quenching constants of 2.371, 1.658, and 0.916x10{sup 5} M{sup -1} at 298, 304, and 310 K, respectively. Binding constants and number of binding sites at different temperatures were also determined by applying the Scatchard method, which in turn were used to construct the van't Hoff plot in order to estimate the enthalpy ({Delta}H) and entropy changes ({Delta}S) for the complexation process. An average of 1.00{+-}0.17 was estimated for the number of sites of BSA, which indicated that STM binds to BSA with stoichiometric ratio of 1:1. The values that were estimated from the van't Hoff plot for {Delta}H and ({Delta}S) were -36.8 kJ mol{sup -1} and -14.9 J mol{sup -1} K{sup -1}, respectively, which indicate that the STM-BSA complex is stabilized with hydrogen bonds and van der Waals interactions. Synchronous fluorescence data was obtained at {Delta}{lambda} of 15 and 60 nm, where obtained results confirmed that STM binds to BSA at the tryptophan residue (Trp. 213). In addition, the distance between STM and the Trp. 213 was estimated via employing the Foerster's non-radiative energy-transfer theory, and was found to be 2.73 nm, which in turn indicated that STM can bind to BSA with high probability. - Research highlights: {yields} Fluorescence data was used to demonstrate that BSA fluorescence can be quenched by STM. {yields} STM can bind to BSA with stoichiometric ratio of 1:1. {yields} STM-BSA complex is

  17. Interaction study on bovine serum albumin physically binding to silver nanoparticles: Evolution from discrete conjugates to protein coronas

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Jun; Zhong, Ruibo; Li, Wanrong; Liu, Yushuang; Bai, Zhijun; Yin, Jun; Liu, Jingran; Gong, Pei [Agricultural Nanocenter, School of Life Science, Inner Mongolia Agricultural University, 306 Zhaowuda Road, Hohhot 010018 (China); Zhao, Xinmin, E-mail: zhao.xinmin@hotmail.com [School of Foreign Language, Inner Mongolia Agricultural University, 306 Zhaowuda Road, Hohhot 010018 (China); Zhang, Feng, E-mail: fengzhang1978@hotmail.com [Agricultural Nanocenter, School of Life Science, Inner Mongolia Agricultural University, 306 Zhaowuda Road, Hohhot 010018 (China)

    2015-12-30

    Graphical abstract: With the non-uniform coating of amphiphilic polymer, the silver nanoparticles (AgNPs) can form protein coronas which can become discrete protein–nanoparticle conjugates when controlling the protein–nanoparticle molar ratios. The protein's conformational changes upon binding NPs was also studied by both circular dichroism and three-dimensional fluorescence spectroscopy. - Highlights: • The amphiphilic polymer coating can not only transfer hydrophobic NPs into water soluble, but also providing a thick shell responsible for the strong physisorption to proteins without significantly changing their spatial conformations. • NP with discrete proteins can be simply obtained by a simple mixing procedure followed by a gel electrophoresis separation, and the resulting conjugates are robust enough to resist common separation techniques like gel electrophoresis. • In combination with the universal amphiphilic polymer coating strategy and the physisorption mediated protein–NP conjugation, proteins like BSA can be effectively conjugated to different materials such as noble metal, semiconductor and magnetic NPs. • In contrast to chemical coupling methods, the physisorption mediated protein–NP conjugation holds facile, robust and reversible advantages, which may find wide applications in nano-biomedicine field. - Abstract: The nanostructures formed by inorganic nanoparticles together with organic molecules especially biomolecules have attracted increasing attention from both industries and researching fields due to their unique hybrid properties. In this paper, we systemically studied the interactions between amphiphilic polymer coated silver nanoparticles and bovine serum albumins by employing the fluorescence quenching approach in combination with the Stern-Volmer and Hill equations. The binding affinity was determined to 1.30 × 10{sup 7} M{sup −1} and the interaction was spontaneously driven by mainly the van der Waals force and

  18. Analysis of binding interaction between the natural apocarotenoid bixin and human serum albumin by circular dichroism and fluorescence spectroscopy.

    Science.gov (United States)

    Zsila, Ferenc; Molnár, Péter; Deli, József

    2005-06-01

    Bixin is an important, pharmacologically active dietary cis-carotenoid, but its interaction with potential macromolecular targets is completely unexplored. This work was aimed to study the binding of bixin to human serum albumin (HSA), the most abundant protein in blood plasma. Circular dichroism (CD) spectroscopy in combination with UV/VIS absorption spectroscopy and fluorescence quenching techniques were applied. Appearance of induced CD bands in the UV- and VIS-absorption spectral regions indicated the formation of non-covalent carotenoid-albumin complexes. Shape and spectral position of the extrinsic Cotton effects suggested the binding of a single bixin molecule to HSA in chiral conformation. Scatchard and non-linear regression analyses of CD titration data resulted in similar values for the association constant (Ka = 6.6 and 4.6x10(5) M(-1), resp.) and for the number of binding sites (n = 1). The binding interaction was independently confirmed by fluorescence-quenching experiment from which the binding parameters were also calculated. CD Displacement measurements performed with marker ligands established that the main drug binding sites of HSA are not involved in binding of bixin. Palmitic acid decreased the amplitude of the induced CD bands suggesting a common albumin binding site for bixin and long-chain fatty acids. The above data indicate that HSA plays a significant role in the plasma transportation of bixin and related dietary carboxylic acid carotenoids.

  19. Investigation into the interaction of losartan with human serum albumin and glycated human serum albumin by spectroscopic and molecular dynamics simulation techniques: A comparison study.

    Science.gov (United States)

    Moeinpour, Farid; Mohseni-Shahri, Fatemeh S; Malaekeh-Nikouei, Bizhan; Nassirli, Hooriyeh

    2016-09-25

    The interaction between losartan and human serum albumin (HSA), as well as its glycated form (gHSA) was studied by multiple spectroscopic techniques and molecular dynamics simulation under physiological conditions. The binding information, including the binding constants, effective quenching constant and number of binding sites showed that the binding partiality of losartan to HSA was higher than to gHSA. The findings of three-dimensional fluorescence spectra demonstrated that the binding of losartan to HSA and gHSA would alter the protein conformation. The distances between Trp residue and the binding sites of the drug were evaluated on the basis of the Förster theory, and it was indicated that non-radiative energy transfer from HSA and gHSA to the losartan happened with a high possibility. According to molecular dynamics simulation, the protein secondary and tertiary structure changes were compared in HSA and gHSA for clarifying the obtained results. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  20. Study on interaction between salicylaldehyde l-serine schiff base and human serum albumin by fluorescence spectroscopy

    Directory of Open Access Journals (Sweden)

    Yang Yanqiu

    2017-01-01

    Full Text Available The interaction of salicylaldehyde L-serine Schiff base (L with human serum albumin (HSA was examined by fluorescence emission spectra at the excitation wavelength 290 nm. Through fluorescence quenching experiments, it was confirmed that the combination of L with HSA was static quenching process. Thermodynamic parameters, such as ΔG, ΔH and ΔS, were calculated at different temperatures, showing that van der Waals force or hydrogen bond interaction were mostly responsible for the binding of L to HSA. The experiments results showed that the microenvironment and the conformation of HSA changed during the binding reaction.

  1. Characteristics and thermodynamics of the interaction of 6-shogaol with human serum albumin as studied by isothermal titration calorimetry

    Directory of Open Access Journals (Sweden)

    Shevin Rizal Feroz

    Full Text Available ABSTRACT The interaction between 6-shogaol, a pharmacologically active ginger constituent, and human serum albumin (HSA, the main in vivo drug transporter, was investigated using isothermal titration calorimetry (ITC. The value of the binding constant, Ka (5.02 ± 1.37 × 104 M−1 obtained for the 6-shogaol-HSA system suggested intermediate affinity. Analysis of the ITC data revealed feasibility of the binding reaction due to favorable enthalpy and entropy changes. The values of the thermodynamic parameters suggested involvement of van der Waals forces, hydrogen bonds and hydrophobic interactions in the 6-shogaol-HSA complex formation.

  2. Nitrogen interactions at metal surfaces

    NARCIS (Netherlands)

    Gleeson, M.A.; Kleijn, A.W.

    2013-01-01

    Molecular beam experiments with specially prepared beams allow the study of the interaction of very reactive species with surfaces. In the present case the interaction of N-atoms with Ag(1 1 1) is studied. The energy of the atoms is around 5 eV, precisely between the classical energy regimes of

  3. Complementary Fluorescence and Phosphorescence Study of the Interaction of Brompheniramine with Human Serum Albumin

    NARCIS (Netherlands)

    Tardioli, S.; mr. Lammers, I.; Hooijschuur, J.H.; Ariese, F.; van der Zwan, G.; Gooijer, C.

    2012-01-01

    Binding of the antihistamine drug brompheniramine (BPA) to human serum albumin (HSA) is studied by measuring quenching of the fluorescence and room temperature phosphorescence (RTP) of tryptophan. The modified Stern-Volmer equation was used to derive association constants and accessible fractions

  4. Study of Interactions of an Anticancer Drug Neratinib With Bovine Serum Albumin: Spectroscopic and Molecular Docking Approach

    Directory of Open Access Journals (Sweden)

    Tanveer A. Wani

    2018-03-01

    Full Text Available Binding of therapeutic agents to plasma proteins, particularly to serum albumin, provides valuable information in the drug development. This study was designed to evaluate the binding interaction of neratinib with bovine serum albumin (BSA. Neratinib blocks HER2 signaling and is effective in trastuzumab-resistant breast cancer treatment. Spectrofluorometric, UV spectrophotometric, and fourier transform infrared (FT-IR and molecular docking experiments were performed to study this interaction. The fluorescence of BSA is attributed to the presence of tryptophan (Trp residues. The fluorescence of BSA in presence of neratinib was studied using the excitation wavelength of 280 nm and the emission was measured at 300-500 nm at three different temperatures. Neratinib quenched the BSA intrinsic fluorescence by static mechanism. A complex formation occurred due to the interaction leading to BSA absorption shift. The fluorescence, UV- absorption, three dimensional fluorescence and FT-IR data showed conformational changes occurred in BSA after interaction with neratinib. The binding constant values decreased as the temperature increased suggesting an instable complex formation at high temperature. Site I (sub-domain IIA was observed as the principal binding site for neratinib. Hydrogen bonding and Van der Waals forces were suggested to be involved in the BSA-neratinib interaction due to the negative values of entropy and enthalpy changes.

  5. Mapping the Interactions between the Alzheimer’s Aβ-Peptide and Human Serum Albumin beyond Domain Resolution

    Science.gov (United States)

    Algamal, Moustafa; Milojevic, Julijana; Jafari, Naeimeh; Zhang, William; Melacini, Giuseppe

    2013-01-01

    Human serum albumin (HSA) is a potent inhibitor of Aβ self-association and this novel, to our knowledge, function of HSA is of potential therapeutic interest for the treatment of Alzheimer’s disease. It is known that HSA interacts with Aβ oligomers through binding sites evenly partitioned across the three albumin domains and with comparable affinities. However, as of this writing, no information is available on the HSA-Aβ interactions beyond domain resolution. Here, we map the HSA-Aβ interactions at subdomain and peptide resolution. We show that each separate subdomain of HSA domain 3 inhibits Aβ self-association. We also show that fatty acids (FAs) compete with Aβ oligomers for binding to domain 3, but the determinant of the HSA/Aβ oligomer interactions are markedly distinct from those of FAs. Although salt bridges with the FA carboxylate determine the FA binding affinities, hydrophobic contacts are pivotal for Aβ oligomer recognition. Specifically, we identified a site of Aβ oligomer recognition that spans the HSA (494–515) region and aligns with the central hydrophobic core of Aβ. The HSA (495–515) segment includes residues affected by FA binding and this segment is prone to self-associate into β-amyloids, suggesting that sites involved in fibrilization may provide a lead to develop inhibitors of Aβ self-association. PMID:24094411

  6. Synthesis of N-(2-chloro purin-6-yl) aza-18-crown-6 and its interaction with human serum albumin.

    Science.gov (United States)

    Li, Cui; Cui, Fengling; Mao, Runze; Huo, Ruina; Qu, Guirong

    2012-01-28

    The synthesis of novel purine nucleosides-linked azacrown ethers in the C6 position, N-(2-chloro purin-6-yl) aza-18-crown-6 (NCPAC), was described. This new nucleoside analogue can be prepared from a series of N9-modified nucleosides and the method allows for new and easy modification of the nucleosides. The interaction between NCPAC and human serum albumin (HSA) was studied using molecular docking and fluorescence techniques. Thermodynamics revealed that the interaction was entropy driven with predominantly hydrophobic forces. From the observed Föster's-type fluorescence resonance energy transfer, the donor (Trp 214 in HSA) to acceptor (NCPAC) distance was calculated to be 3.6 nm. The conformational changes of HSA due to the interaction were investigated qualitatively from synchronous fluorescence spectra. Molecular docking studies were performed to obtain information on the possible residues involved in the interaction process.

  7. Interactions of nanobubbles with bovine serum albumin and papain films on gold surfaces

    Czech Academy of Sciences Publication Activity Database

    Kolivoška, Viliam; Gál, Miroslav; Hromadová, Magdaléna; Lachmanová, Štěpánka; Pospíšil, Lubomír

    2011-01-01

    Roč. 6, č. 4 (2011), s. 164-170 ISSN 1559-4106 R&D Projects: GA ČR GP203/09/P502; GA ČR GA203/09/0705; GA ČR GA203/08/1157; GA AV ČR IAA400400802 Institutional research plan: CEZ:AV0Z40400503 Keywords : nanobubbles * bovine serum albumin * gold surfaces Subject RIV: CG - Electrochemistry Impact factor: 3.118, year: 2010

  8. Molecular modeling and multispectroscopic studies of the interaction of hepatitis B drug, adefovir dipivoxil with human serum albumin

    Energy Technology Data Exchange (ETDEWEB)

    Shahabadi, Nahid, E-mail: nahidshahabadi@yahoo.com [Department of Chemistry, Faculty of Science, Razi University, Kermanshah (Iran, Islamic Republic of); Medical Biology Research Center (MBRC) Kermanshah University of Medical Sciences, Kermanshah (Iran, Islamic Republic of); Falsafi, Monireh [Department of Chemistry, Faculty of Science, Razi University, Kermanshah (Iran, Islamic Republic of); Hadidi, Saba [Department of Chemistry, Faculty of Science, Razi University, Kermanshah (Iran, Islamic Republic of); Medical Biology Research Center (MBRC) Kermanshah University of Medical Sciences, Kermanshah (Iran, Islamic Republic of)

    2015-11-15

    The interaction of hepatitis B drug, adefovir dipivoxil with human serum albumin (HSA) was studied by using UV–vis, fluorometric, circular dichroism (CD) and molecular docking techniques. The results indicated that the binding of the drug to HSA caused fluorescence quenching through static quenching mechanism with binding constant of 1.3×103 M{sup −1}. The thermodynamic parameters indicated that the hydrophobic force contacts are the major forces in the stability of protein-drug complex (ΔH>0 and ΔS>0). The displacement experiments using the site probes viz., warfarin and ibuprofen showed that adefovir dipivoxil could bind to the site III of HSA. The results of CD and UV–vis spectroscopy indicated that the binding of the drug induced some conformational changes in HSA. Furthermore, the study of molecular docking also confirmed binding of adefovir dipivoxil to the site III of HSA by hydrophobic interaction. - Highlights: • The interaction of adefovir dipivoxil, drug for the treatment of HIV and HBV with human serum albumin (HSA) is investigated. • The drug bound to HSA by hydrophobic force and induced some conformational changes in HSA. • The study of molecular docking showed that adefovir dipivoxil could bind to the site III of HSA mainly.

  9. Molecular modeling and multispectroscopic studies of the interaction of hepatitis B drug, adefovir dipivoxil with human serum albumin

    International Nuclear Information System (INIS)

    Shahabadi, Nahid; Falsafi, Monireh; Hadidi, Saba

    2015-01-01

    The interaction of hepatitis B drug, adefovir dipivoxil with human serum albumin (HSA) was studied by using UV–vis, fluorometric, circular dichroism (CD) and molecular docking techniques. The results indicated that the binding of the drug to HSA caused fluorescence quenching through static quenching mechanism with binding constant of 1.3×103 M −1 . The thermodynamic parameters indicated that the hydrophobic force contacts are the major forces in the stability of protein-drug complex (ΔH>0 and ΔS>0). The displacement experiments using the site probes viz., warfarin and ibuprofen showed that adefovir dipivoxil could bind to the site III of HSA. The results of CD and UV–vis spectroscopy indicated that the binding of the drug induced some conformational changes in HSA. Furthermore, the study of molecular docking also confirmed binding of adefovir dipivoxil to the site III of HSA by hydrophobic interaction. - Highlights: • The interaction of adefovir dipivoxil, drug for the treatment of HIV and HBV with human serum albumin (HSA) is investigated. • The drug bound to HSA by hydrophobic force and induced some conformational changes in HSA. • The study of molecular docking showed that adefovir dipivoxil could bind to the site III of HSA mainly

  10. STUDIES ON THE INTERACTION BETWEEN TRIPTOLIDE AND BOVINE SERUM ALBUMIN (BSA) BY SPECTROSCOPIC AND MOLECULAR MODELING METHODS.

    Science.gov (United States)

    Wang, Haidong; Shi, Hailang; Pang, Jie; Song, Xingfa; Xu, Caiyun; Sun, Zengxian

    2016-01-01

    Triptolide is a major active constituent isolated from Tripterygiumwilfordii Hook F, a Chinese herbal medicine. This study investigated the intermolecular interaction between triptolide and bovine serum albumin (BSA). The fluorescence, circular dichroism (CD) and molecular docking methods were used to investigate the intermolecular interaction between triptolide and BSA. The binding constant, the number of binding sites, binding subdomain and the thermodynamic parameters were measured. The results of this experiment revealed that the intrinsic fluorescence of BSA was effectively quenched by triptolide via static quenching. The experimental results of synchronous fluorescence and CD spectra showed that the conformation of BSA was changed in the presence of triptolide. It indicated that triptolide could spontaneously bind on site II (subdomain IIIA) of BSA mainly via hydrogen bonding interactions and Van der Waals force.

  11. Probing the interaction of human serum albumin with DPPH in the absence and presence of the eight antioxidants.

    Science.gov (United States)

    Li, Xiangrong; Chen, Dejun; Wang, Gongke; Lu, Yan

    2015-02-25

    Albumin represents a very abundant and important circulating antioxidant in plasma. DPPH radical is also called 2,2-diphenyl-1-picrylhydrazyl. It has been widely used for measuring the efficiency of antioxidants. In this paper, the ability of human serum albumin (HSA) to scavenge DPPH radical was investigated using UV-vis absorption spectra. The interaction between HSA and DPPH was investigated in the absence and presence of eight popular antioxidants using fluorescence spectroscopy. These results indicate the antioxidant activity of HSA against DPPH radical is similar to glutathione and the value of IC50 is 5.200×10(-5) mol L(-1). In addition, the fluorescence experiments indicate the quenching mechanism of HSA, by DPPH, is a static process. The quenching process of DPPH with HSA is easily affected by the eight antioxidants, however, they cannot change the quenching mechanism of DPPH with HSA. The binding of DPPH to HSA primarily takes place in subdomain IIA and exists two classes of binding sites with two different interaction behaviors. The decreased binding constants and the number of binding sites of DPPH with HSA by the introduction of the eight antioxidants may result from the competition of the eight antioxidants and DPPH binding to HSA. The binding of DPPH to HSA may induce the micro-environment of the lone Trp-214 from polar to slightly nonpolar. Copyright © 2014 Elsevier B.V. All rights reserved.

  12. Interaction Of Hydrogen With Metal Alloys

    Science.gov (United States)

    Danford, M. D.; Montano, J. W.

    1993-01-01

    Report describes experiments on interaction of hydrogen with number of metal alloys. Discusses relationship between metallurgical and crystallographic aspects of structures of alloys and observed distributions of hydrogen on charging. Also discusses effect of formation of hydrides on resistances of alloys to hydrogen. Describes attempt to correlate structures and compositions of alloys with their abilities to resist embrittlement by hydrogen.

  13. Spectroscopic analyses and studies on respective interaction of cyanuric acid and uric acid with bovine serum albumin and melamine

    Science.gov (United States)

    Chen, Dandan; Wu, Qiong; Wang, Jun; Wang, Qi; Qiao, Heng

    2015-01-01

    In this work, the fluorescence quenching was used to study the interaction of cyanuric acid (CYA) and uric acid (UA) with bovine serum albumin (BSA) at two different temperatures (283 K and 310 K). The bimolecular quenching constant (Kq), apparent quenching constant (Ksv), effective binding constant (KA) and corresponding dissociation constant (KD), binding site number (n) and binding distance (r) were calculated by adopting Stern-Volmer, Lineweaver-Burk, Double logarithm and overlap integral equations. The results show that CYA and UA are both able to obviously bind to BSA, but the binding strength order is BSA + CYA < BSA + UA. And then, the interactions of CYA and UA with melamine (MEL) under the same conditions were also studied by using similar methods. The results indicates that both CYA and UA can bind together closely with melamine (MEL). It is wished that these research results would facilitate the understanding the formation of kidney stones and gout in the body after ingesting excess MEL.

  14. The fluorescence spectroscopic study on the interaction between imidazo[2,1-b]thiazole analogues and bovine serum albumin

    Science.gov (United States)

    Yu, Xianyong; Yang, Ying; Shiyu, Lu; Yao, Qing; Heting, Liu; Xiaofang, Li; Pinggui, Yi

    2011-12-01

    The interaction between imidazo[2,1-b]thiazole (IMTZ) and bovine serum albumin (BSA) was analyzed by fluorescence and ultraviolet spectroscopy at 302 and 310 K under simulative physiological conditions. The results show that IMTZ can effectively quench the intrinsic fluorescence of BSA via static and dynamic quenching. The binding constant, binding sites of IMTZ with BSA were calculated. According to the Förster non-radiation energy transfer theory, the average binding distance between IMTZ and BSA was obtained. What's more, the synchronous fluorescence spectra indicated that the conformation of BSA has been changed. The results provided the information for the binding of IMTZ to BSA, and the influences of substituent group on the interaction were also discussed.

  15. Microbial virulence and interactions with metals

    DEFF Research Database (Denmark)

    German, N.; Lüthje, Freja Lea; Hao, X.

    2016-01-01

    Transition metals, such as iron, copper, zinc, and manganese play an important role in many bacterial biological processes that add to an overall evolutional fitness of bacteria. They are often involved in regulation of bacterial virulence as a mechanism of host invasion. However, the same transi...... reconstruction of Fe-S clusters and the use of Mn as a protectant against reactive oxygen species. Therefore, tight regulation of transition metal distribution in bacteria and hosts is a vital part of host-pathogen interactions....

  16. Metal-metal interactions among dietary toxic and essential trace metals in the rat

    Energy Technology Data Exchange (ETDEWEB)

    Elsenhans, B.; Schmolke, G.; Kolb, K.; Stokes, J.; Forth, W.

    1987-12-01

    Exposure to toxic and essential metals is thought to be reflected by corresponding metal concentrations in tissues. However, toxic and essential metals may influence each other in regard to their retention in the body. Therefore, a basic diet containing four toxic metals (As 7, Cd 9, Ni 13, and Pb 20 ppm) and adequate amounts of essential metals was fed to rats for 2 weeks. Test groups received the basic diet with increasing concentrations of one of the toxic metals (up to 90 ppm As, 180 ppm Cd, 365 ppm Ni, and 394 ppm Pb). As, Cd, Ni, Pb, Cu, Fe, Mn, and Zn were determined by atomic emission spectroscopy in liver, kidney, intestine, brain, muscle, bone, skin, hair, and blood. A linear relationship between diet and tissue concentration is observed for As and Ni in the kidney, for Cd in the liver, and for Pb in the bone. In other tissues saturation was observed. While Cd-Fe interactions were common to most of the tissues, other interactions were detected only in specific tissues, e.g., As-Cu in the kidney, Cd-Zn in the liver, and As-Mn, Cd-Mn, or Ni-Cu in the intestine. Increases of renal Pb and intestinal Cd by dietary Ni, and a decrease in bone As by dietary Pb were the most pronounced interactions between the toxic metals. The results demonstrate that potential target organs for the evaluation of metal exposure need to be carefully analyzed for interfering metal-metal interactions.

  17. Evaluation of the interactions between human serum albumin (HSA and warfarin or diflunisal by using molecular fluorescence using two approaches

    Directory of Open Access Journals (Sweden)

    Susana Amézqueta

    2018-03-01

    Full Text Available Serum albumin is the main drug transporter of the bloodstream and contains two main binding sites:  Sudlow I or acidic drug binding site, and Sudlow II or benzodiazepine binding site. Warfarin, a well-known anticoagulant drug commonly used in the prevention of thrombosis and thromboembolism, binds to Sudlow I site, whereas non-steroidal antiinflammatory drugs (NSAIDs such as diflunisal bind preferentially to Sudlow II site.  Albumin is a fluorophore that modifies its fluorescence (quenching or enhancement effect when it is bound to a drug. The application of the double logarithm Stern-Volmer equation allows the calculation of the stoichiometry and the binding constant of the process. This procedure does not consider the possible interferences coming from the fluorescence of the drug though. Another strategy to evaluate the binding constants is to consider the whole spectrum, taking into account all the possible species in equilibrium; in this case we have used an extended version of the STAR program, which can deal with 300 spectra, each containing up to 300 data points. The aim of this work is to compare both approaches to evaluate the interaction between warfarin (Sudlow I and diflunisal (Sudlow II and HSA: the double logarithm Stern-Volmer equation and the STAR program.

  18. Combined spectroscopic and molecular docking techniques to study interaction of Zn (II) DiAmsar with serum albumins

    Energy Technology Data Exchange (ETDEWEB)

    Bardajee, Ghasem Rezanejade, E-mail: rezanejad@pnu.ac.ir; Hooshyar, Zari; Shafagh, Pegah; Ghiasvand, Samira; Kakavand, Nahaleh

    2014-12-15

    Zinc (II) diamine-sarcophagine (Zn (II) DiAmsar) as a water soluble hexadentate ligand was synthesized and characterized by nuclear magnetic resonance (NMR), Fourier transform infrared (FT-IR) and UV–visible (UV–vis) spectroscopy. The bindings of Zn (II) DiAmsar with human serum albumin (HSA) and bovine serum albumin (BSA) were investigated under the simulative physiological conditions. To study this binding, the fluorescence spectra in combination with FT-IR, UV–vis, cyclic voltammetry (CV), and molecular docking techniques were used in the present work. The results indicate that Zn (II) DiAmsar quenched effectively the intrinsic fluorescence of HSA and BSA via a static quenching process. The fluorescence quenching data was also used to determine binding sites and binding constants at different temperatures. The calculated thermodynamic parameters (∆G°, ∆H°, and ∆S°) suggest that the binding process occurs spontaneously by involving hydrogen bond and van der Waals interactions. The distance between HSA (or BSA) as a donor and Zn (II) DiAmsar as an acceptor was obtained according to fluorescence resonance energy transfer (FRET). In addition, the docking results revealed the possible binding sites and assess the microenvironment around the bounded Zn (II) DiAmsar.

  19. Influence of galloyl moiety in interaction of epicatechin with bovine serum albumin: a spectroscopic and thermodynamic characterization.

    Science.gov (United States)

    Pal, Sandip; Saha, Chabita; Hossain, Maidul; Dey, Subrata Kumar; Kumar, Gopinatha Suresh

    2012-01-01

    The health benefits stemming from green tea are well known, but the exact mechanism of its biological activity is not elucidated. Epicatechin (EC) and epicatechin gallate (ECG) are two dietary catechins ubiquitously present in green tea. Serum albumins functionally carry these catechins through the circulatory system and eliminate reactive oxygen species (ROS) induced injury. In the present study ECG is observed to have higher antioxidant activity; which is attributed to the presence of galloyl moiety. The binding affinity of these catechins to bovine serum albumin (BSA) will govern the efficacy of their biological activity. EC and ECG bind with BSA with binding constants 1.0 × 10(6) M(-1) and 6.6 × 10(7) M(-1), respectively. Changes in secondary structure of BSA on interaction with EC and ECG have been identified by circular dichroism (CD) and Fourier transform infrared (FT-IR) spectroscopy. Thermodynamic characterization reveals the binding process to be exothermic, spontaneous and entropy driven. Mixed binding forces (hydrophobic, electrostatic and hydrogen bonding) exist between ECG and BSA. Binding site for EC is primarily site-II in sub-domain IIIA of BSA and for ECG; it is site-I in sub-domain IIA. ECG with its high antioxidant activity accompanied by high affinity for BSA could be a model in drug designing.

  20. Influence of galloyl moiety in interaction of epicatechin with bovine serum albumin: a spectroscopic and thermodynamic characterization.

    Directory of Open Access Journals (Sweden)

    Sandip Pal

    Full Text Available The health benefits stemming from green tea are well known, but the exact mechanism of its biological activity is not elucidated. Epicatechin (EC and epicatechin gallate (ECG are two dietary catechins ubiquitously present in green tea. Serum albumins functionally carry these catechins through the circulatory system and eliminate reactive oxygen species (ROS induced injury. In the present study ECG is observed to have higher antioxidant activity; which is attributed to the presence of galloyl moiety. The binding affinity of these catechins to bovine serum albumin (BSA will govern the efficacy of their biological activity. EC and ECG bind with BSA with binding constants 1.0 × 10(6 M(-1 and 6.6 × 10(7 M(-1, respectively. Changes in secondary structure of BSA on interaction with EC and ECG have been identified by circular dichroism (CD and Fourier transform infrared (FT-IR spectroscopy. Thermodynamic characterization reveals the binding process to be exothermic, spontaneous and entropy driven. Mixed binding forces (hydrophobic, electrostatic and hydrogen bonding exist between ECG and BSA. Binding site for EC is primarily site-II in sub-domain IIIA of BSA and for ECG; it is site-I in sub-domain IIA. ECG with its high antioxidant activity accompanied by high affinity for BSA could be a model in drug designing.

  1. Adsorption behavior of oxidized galactomannans onto amino terminated surfaces and their interaction with bovine serum albumin

    Energy Technology Data Exchange (ETDEWEB)

    Sierakowski, M.-R; Silva, Maria R.V. da [Universidade Federal do Parana, Curitiba, PR (Brazil). Dept. de Quimica. Lab. de Biopolimeros]. E-mail: mrbiopol@quimica.ufpr.br; Freitas, R.A.; Moreira, Jose S.R. [Universidade Federal do Parana, Curitiba, PR (Brazil). Dept. de Bioquimica; Fujimoto, J.; Petri, D.F.S.; Cordeiro, Paulo R.D. [Sao Paulo Univ., SP (Brazil). Inst. de Quimica]. E-mail: dfsp@quim.iq.usp.br; Andrade, Fabiana D

    2001-07-01

    A galactomannan (CF) extracted from Cassia fastuosa seeds was purified and oxidized with (2,2,6,6- tetramethylpiperidine-1-oxyl) to form a uronic acid-containing polysaccharide (CFOX) with a degree of oxidation (DO) of 0.22. The chemical structures of CF and CFOX were characterized. The adsorption behavior of CF and CFOX onto amino-terminated surfaces was studied by means of ellipsometric measurements. The influence of p H and ionic strength on the adsorption was also investigated. At p H 4, there was a maximum in the adsorbed amount caused by strong electrostatic attraction between the substrate and the oxidized galactomannans. There was no ionic strength effect on the adsorption behavior. The immobilization of bovine serum albumin onto CF and CFOX was studied as a function of p H. At the isoelectric point a maximum in the adsorbed amount was found. (author)

  2. Adsorption behavior of oxidized galactomannans onto amino terminated surfaces and their interaction with bovine serum albumin

    International Nuclear Information System (INIS)

    Sierakowski, M.-R; Silva, Maria R.V. da; Freitas, R.A.; Moreira, Jose S.R.; Fujimoto, J.; Petri, D.F.S.; Cordeiro, Paulo R.D.; Andrade, Fabiana D.

    2001-01-01

    A galactomannan (CF) extracted from Cassia fastuosa seeds was purified and oxidized with (2,2,6,6- tetramethylpiperidine-1-oxyl) to form a uronic acid-containing polysaccharide (CFOX) with a degree of oxidation (DO) of 0.22. The chemical structures of CF and CFOX were characterized. The adsorption behavior of CF and CFOX onto amino-terminated surfaces was studied by means of ellipsometric measurements. The influence of p H and ionic strength on the adsorption was also investigated. At p H 4, there was a maximum in the adsorbed amount caused by strong electrostatic attraction between the substrate and the oxidized galactomannans. There was no ionic strength effect on the adsorption behavior. The immobilization of bovine serum albumin onto CF and CFOX was studied as a function of p H. At the isoelectric point a maximum in the adsorbed amount was found. (author)

  3. NMR diffusion and relaxation studies of 2-nitroimidazole and albumin interactions

    Science.gov (United States)

    Wijesekera, Dj; Willis, Scott A.; Gupta, Abhishek; Torres, Allan M.; Zheng, Gang; Price, William S.

    2018-03-01

    Nitroimidazole derivatives are of current interest in the development of hypoxia targeting agents and show potential in the establishment of quantitative measures of tumor hypoxia. In this study, the binding of 2-nitroimidazole to albumin was probed using NMR diffusion and relaxation measurements. Binding studies were conducted at three different protein concentrations (0.23, 0.30 and 0.38 mM) with drug concentrations ranging from 0.005-0.16 M at 298 K. Quantitative assessments of the binding model were made by evaluating the number of binding sites, n, and association constant, K. These were determined to be 21 ± 3 and 53 ± 4 M- 1, respectively.

  4. [Synthesis of purpure-18-imide and study on its interaction with bovine serum albumins by fluorescence].

    Science.gov (United States)

    Wang, Jin-jun; Liu, Yong-ming; Li, Li

    2005-04-01

    Purpure-18-imide was synthesized based on the porphyrin's special affinity for cancer cells and the antitumor activity of pyrrolidine compound. The binding reaction between purpure-18-imide and bovine serum albumins (BSA) in aqueous was studied by fluorescence and UV-Vis absorption spectra. The research results indicated that the combination reaction of them was a single static quenching process. In aqueous, purpure-18-imide strongly bound BSA with molar ratio of 1:1. The binding constant K0 was 5.386 x 10(5) L x mol(-1). The shortest binding distance (r = 3.54 nm) and energy transfer efficiencies (E = 0.26) between donor (BSA) and acceptor (purpure-18-imide) were obtained by Forster's nonradiative energy transfer mechanism.

  5. The Investigation of the Interaction between Lomefloxacin and Human Serume Albumin by Specteroscopic Methods

    Directory of Open Access Journals (Sweden)

    F. S. Goldouzian

    2012-03-01

    Full Text Available Mechanism of the binding of lomefloxacin (LMF with human serum albumin has been studied at physiological pH (7.4 using fluorescence spectroscopic technique. LMF is a third-generation fluoroquinolone antibiotic that exhibits striking potency against a broad spectrum of Gram-negative and Gram-positive bacteria through inhibition of DNA gyrase. Lomefloxacin is a drug that is excreted in urine and has very variable systemic absorption. Human serum albumin (HSA is the most important and abundant constituent of blood plasma and serves as a protein storage component. Recently, the three-dimensional structure of HSA was determined through X-ray crystallographic measurement. Fluorescence studies showed that (LMF has an ability to quench the intrinsic fluorescence of HSA through a static quenching  procedure  according to the Stern–Volmer equation .LMF showed two types of binding sites, the first having a very high affinity (1/72 ×107M-1 and a secondary binding site with an affinity two orders lower than the primary site. The number of binding sites for complex: HSA-LMF at 280 nm was calculated 1and0.5. The microenvironment of tryptophan and tyrosin residues and more hydrophobic of fluorophores microenvironment were changed and disturbed by the blue shift in maximum wavelength and decreased in fluorescence intensity in the presence of lomefloxacin revealed  decreased polarity of the fluorophores. The binding site for LMF is in a hydrophobic pocket in the sub-domain II A of HSA.

  6. Interaction of bovine serum albumin and lysozyme with stainless steel studied by time-of-flight secondary ion mass spectrometry and X-ray photoelectron spectroscopy.

    Science.gov (United States)

    Hedberg, Yolanda S; Killian, Manuela S; Blomberg, Eva; Virtanen, Sannakaisa; Schmuki, Patrik; Odnevall Wallinder, Inger

    2012-11-27

    An in-depth mechanistic understanding of the interaction between stainless steel surfaces and proteins is essential from a corrosion and protein-induced metal release perspective when stainless steel is used in surgical implants and in food applications. The interaction between lysozyme (LSZ) from chicken egg white and bovine serum albumin (BSA) and AISI 316L stainless steel surfaces was studied ex situ by means of X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS) after different adsorption time periods (0.5, 24, and 168 h). The effect of XPS measurements, storage (aging), sodium dodecyl sulfate (SDS), and elevated temperature (up to 200 °C) on the protein layers, as well as changes in surface oxide composition, were investigated. Both BSA and LSZ adsorption induced an enrichment of chromium in the oxide layer. BSA induced significant changes to the entire oxide, while LSZ only induced a depletion of iron at the utmost layer. SDS was not able to remove preadsorbed proteins completely, despite its high concentration and relatively long treatment time (up to 36.5 h), but induced partial denaturation of the protein coatings. High-temperature treatment (200 °C) and XPS exposure (X-ray irradiation and/or photoelectron emission) induced significant denaturation of both proteins. The heating treatment up to 200 °C removed some proteins, far from all. Amino acid fragment intensities determined from ToF-SIMS are discussed in terms of significant differences with adsorption time, between the proteins, and between freshly adsorbed and aged samples. Stainless steel-protein interactions were shown to be strong and protein-dependent. The findings assist in the understanding of previous studies of metal release and surface changes upon exposure to similar protein solutions.

  7. Multispectroscopic and molecular modeling approach to investigate the interaction of diclofop-methyl enantiomers with human serum albumin

    International Nuclear Information System (INIS)

    Zhang, Ping; Liu, Donghui; Li, Zhe; Shen, Zhigang; Wang, Peng; Zhou, Meng; Zhou, Zhiqiang; Zhu, Wentao

    2014-01-01

    Pesticides and related environmental contaminants have always been threated to human health due to their intrinsic toxicity. In the context of this contribution, the interaction between diclofop-methyl (DM) enantiomers and human serum albumin (HSA) has been characterized by steady state and three-dimensional fluorescence, molecular modeling, circular dichroism (CD) and ultraviolet–visible (UV–vis) spectroscopy. The binding constants significantly showed the binding was enantioselective and HSA had higher affinity for S-DM. The thermodynamic parameters of the binding reaction (ΔG, ΔH and ΔS) clearly signified that hydrophobic effects and H-bonds contribute to the formation of DM-HSA complex. The alterations of protein secondary structure in the presence of DM enantiomers were confirmed by CD spectroscopy, UV–vis and three-dimensional fluorescence spectroscopy. In addition, both fluorescence probe study and molecular modeling simulation evidenced the binding of DM enantiomers to HSA primarily took place in subdomain IIIA (Sudlow's site II). This investigation highlights the binding mechanism, specific binding sites and binding region of DM enantiomers on human serum albumin at the first time. Besides, such task can provide important insight to the interaction of the physiological protein HSA with chiral aryloxyphenoxypropionate herbicides and give support to the human health risk assessment. - Highlights: • The binding of DM enantiomers to HSA was enantioselective. • HSA had higher affinity for S-DM than R-DM. • Hydrophobic effects and hydrogen bonds were involved in the DM-HSA interaction. • The binding of DM enantiomers to HSA primarily took place in Sudlow's site II. • DM enantiomers could alter the second structure of HSA

  8. Interaction mechanisms between organic UV filters and bovine serum albumin as determined by comprehensive spectroscopy exploration and molecular docking.

    Science.gov (United States)

    Ao, Junjie; Gao, Li; Yuan, Tao; Jiang, Gaofeng

    2015-01-01

    Organic UV filters are a group of emerging PPCP (pharmaceuticals and personal care products) contaminants. Current information is insufficient to understand the in vivo processes and health risks of organic UV filters in humans. The interaction mechanism of UV filters with serum albumin provides critical information for the health risk assessment of these active ingredients in sunscreen products. This study investigates the interaction mechanisms of five commonly used UV filters (2-hydroxy-4-methoxybenzophenone, BP-3; 2-ethylhexyl 4-methoxycinnamate, EHMC; 4-methylbenzylidene camphor, 4-MBC; methoxydibenzoylmethane, BDM; homosalate, HMS) with bovine serum albumin (BSA) by spectroscopic measurements of fluorescence, circular dichroism (CD), competitive binding experiments and molecular docking. Our results indicated that the fluorescence of BSA was quenched by these UV filters through a static quenching mechanism. The values of the binding constant (Ka) ranged from (0.78±0.02)×10(3) to (1.29±0.01)×10(5) L mol(-1). Further exploration by synchronous fluorescence and CD showed that the conformation of BSA was demonstrably changed in the presence of these organic UV filters. It was confirmed that the UV filters can disrupt the α-helical stability of BSA. Moreover, the results of molecular docking revealed that the UV filter molecule is located in site II (sub-domain IIIA) of BSA, which was further confirmed by the results of competitive binding experiments. In addition, binding occurred mainly through hydrogen bonding and hydrophobic interaction. This study raises critical concerns regarding the transportation, distribution and toxicity effects of organic UV filters in human body. Copyright © 2014 Elsevier Ltd. All rights reserved.

  9. Multispectroscopic and molecular modeling approach to investigate the interaction of diclofop-methyl enantiomers with human serum albumin

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Ping; Liu, Donghui; Li, Zhe; Shen, Zhigang; Wang, Peng [Department of Applied Chemistry, China Agricultural University, Beijing 100193 (China); Zhou, Meng [Business School, University of Bedfordshire, Luton LU1 3JU (United Kingdom); Zhou, Zhiqiang [Department of Applied Chemistry, China Agricultural University, Beijing 100193 (China); Zhu, Wentao, E-mail: wentaozhu@cau.edu.cn [Department of Applied Chemistry, China Agricultural University, Beijing 100193 (China)

    2014-11-15

    Pesticides and related environmental contaminants have always been threated to human health due to their intrinsic toxicity. In the context of this contribution, the interaction between diclofop-methyl (DM) enantiomers and human serum albumin (HSA) has been characterized by steady state and three-dimensional fluorescence, molecular modeling, circular dichroism (CD) and ultraviolet–visible (UV–vis) spectroscopy. The binding constants significantly showed the binding was enantioselective and HSA had higher affinity for S-DM. The thermodynamic parameters of the binding reaction (ΔG, ΔH and ΔS) clearly signified that hydrophobic effects and H-bonds contribute to the formation of DM-HSA complex. The alterations of protein secondary structure in the presence of DM enantiomers were confirmed by CD spectroscopy, UV–vis and three-dimensional fluorescence spectroscopy. In addition, both fluorescence probe study and molecular modeling simulation evidenced the binding of DM enantiomers to HSA primarily took place in subdomain IIIA (Sudlow's site II). This investigation highlights the binding mechanism, specific binding sites and binding region of DM enantiomers on human serum albumin at the first time. Besides, such task can provide important insight to the interaction of the physiological protein HSA with chiral aryloxyphenoxypropionate herbicides and give support to the human health risk assessment. - Highlights: • The binding of DM enantiomers to HSA was enantioselective. • HSA had higher affinity for S-DM than R-DM. • Hydrophobic effects and hydrogen bonds were involved in the DM-HSA interaction. • The binding of DM enantiomers to HSA primarily took place in Sudlow's site II. • DM enantiomers could alter the second structure of HSA.

  10. Investigation of Non-Covalent Interactions of Aflatoxins (B1, B2, G1, G2, and M1 with Serum Albumin

    Directory of Open Access Journals (Sweden)

    Miklós Poór

    2017-10-01

    Full Text Available Aflatoxins are widely spread mycotoxins produced mainly by Aspergillus species. Consumption of aflatoxin-contaminated foods and drinks causes serious health risks for people worldwide. It is well-known that the reactive epoxide metabolite of aflatoxin B1 (AFB1 forms covalent adducts with serum albumin. However, non-covalent interactions of aflatoxins with human serum albumin (HSA are poorly characterized. Thus, in this study the complex formation of aflatoxins was examined with HSA applying spectroscopic and molecular modelling studies. Our results demonstrate that aflatoxins form stable complexes with HSA as reflected by binding constants between 2.1 × 104 and 4.5 × 104 dm3/mol. A binding free energy value of −26.90 kJ mol−1 suggests a spontaneous binding process between AFB1 and HSA at room-temperature, while the positive entropy change of 55.1 JK−1 mol−1 indicates a partial decomposition of the solvation shells of the interacting molecules. Modeling studies and investigations with site markers suggest that Sudlow’s Site I of subdomain IIA is the high affinity binding site of aflatoxins on HSA. Interaction of AFB1 with bovine, porcine, and rat serum albumins was also investigated. Similar stabilities of the examined AFB1-albumin complexes were observed suggesting the low species differences of the albumin-binding of aflatoxins.

  11. Study on the molecular interaction of graphene quantum dots with human serum albumin: Combined spectroscopic and electrochemical approaches

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Shan; Qiu, Hangna; Lu, Shuangyan; Zhu, Fawei [College of Chemistry and Material Science, Guangxi Teachers Education University, Nanning 530001 (China); Xiao, Qi, E-mail: qi.xiao@whu.edu.cn [College of Chemistry and Material Science, Guangxi Teachers Education University, Nanning 530001 (China); State Key Laboratory of Virology, College of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072 (China)

    2015-03-21

    Highlights: • The interactions between GQDs and HSA were systematically investigated. • GQDs could quench the intrinsic fluorescence of HSA via static mode. • The binding site of GQDs was mainly located in site I of HSA. • The potential toxicity of GQDs resulted in the structural damage of HSA. - Abstract: Graphene quantum dots (GQDs) have attracted great attention in biological and biomedical applications due to their super properties, but their potential toxicity investigations are rarely involved. Since few studies have addressed whether GQDs could bind and alter the structure and function of human serum albumin (HSA), the molecular interaction between GQDs and HSA was systematically characterized by the combination of multispectroscopic and electrochemical approaches. GQDs could quench the intrinsic fluorescence of HSA via static mode. The competitive binding fluorescence assay revealed that the binding site of GQDs was site I of HSA. Some thermodynamic parameters suggested that GQDs interacted with HSA mainly through van der Waals interactions and hydrogen bonding interactions, and protonation might also participate in the process. As further revealed by FT-IR spectroscopy and circular dichroism technique, GQDs could cause the global and local conformational change of HSA, which illustrated the potential toxicity of GQDs that resulted in the structural damage of HSA. Electrochemical techniques demonstrated the complex formation between GQDs and HSA. Our results offered insights into the binding mechanism of GQDs with HSA and provided important information for possible toxicity risk of GQDs to human health.

  12. Multispectroscopic Investigation of the Interaction Between two Ruthenium(II) Arene Complexes of Curcumin Analogs and Human Serum Albumin.

    Science.gov (United States)

    Huang, Shan; Peng, Shushu; Zhu, Fawei; Lei, Xiaolin; Xiao, Qi; Su, Wei; Liu, Yi; Huang, Chusheng; Zhang, Lixia

    2016-02-01

    The interaction between two ruthenium(II) arene complexes of curcumin analogs and human serum albumin (HSA) was systematically investigated by multispectroscopic techniques. The fluorescence spectral results indicated that two complexes quenched the intrinsic fluorescence of HSA through static quenching mode. The quenching constants and the corresponding thermodynamic parameters at different temperatures were calculated. The binding interactions of two complexes with HSA resulted in the complex formation of complex-HSA, and the van der Waals interactions and hydrogen bond interactions played major roles in the complex stabilization. The distances between HSA and two complexes were obtained according to fluorescence resonance energy transfer theory. The site competitive replacement experiments illustrated that two complexes mainly bounded with HSA on site I. The results of synchronous fluorescence spectra, three-dimensional fluorescence spectra, FT-IR spectra, and circular dichroism spectra indicated that the secondary structure of HSA was changed at the present of two complexes. The results of mass spectrometry further validated the binding interaction and the binding number between two complexes and HSA.

  13. Interaction of hydrogen with metallic nanojunctions

    Energy Technology Data Exchange (ETDEWEB)

    Halbritter, Andras; Csonka, Szabolcs; Makk, Peter; Mihaly, Gyoergy [Electron Transport Research Group of the Hungarian Academy of Sciences and Department of Physics, Budapest University of Technology and Economics, 1111 Budapest (Hungary)

    2007-03-15

    We study the behavior of hydrogen molecules between atomic-sized metallic electrodes using the mechanically controllable break junction technique. We focus on the interaction H{sub 2} with monoatomic gold chains demonstrating the possibility of a hydrogen molecule being incorporated in the chain. We also show that niobium is strongly reactive with hydrogen, which enables molecular transport studies between superconducting electrodes. This opens the possibility for a full characterization of the transmission properties of molecular junctions with superconducting subgap structure measurements.

  14. Magnetic Interactions in Transition-Metal Oxides

    OpenAIRE

    Solovyev, I. V.

    2003-01-01

    This a review article, which presents a general framework for the analysis of interatomic magnetic interactions in the spin-density-functional theory, which is based on the magnetic force theorem, make a link with the models for transition-metal oxides, and gives several examples of how this strategy can be used for the analysis of magnetic properties of colossal-magnetoresistive perovskite manganites, double perovskite and pyrochlore compounds.

  15. Commentary on "Spectral characterization of the binding and conformational changes of serum albumins upon interaction with an anticancer drug, anastrozole"

    Science.gov (United States)

    Korkmaz, Filiz

    2015-03-01

    The manuscript by R. Punith and J. Seetharamappa (http://dx.doi.org/10.1016/j.saa.201202.038) presents the interaction between serum albumin from human (HAS) and from bovine (BSA) with a drug called Anastrozole (AZ). The drug is on the market for treating patients with breast cancer after surgery and for metastasis in women. The study utilizes various spectroscopic techniques such as; fluorescence, synchronous fluorescence, 3D fluorescence measurements, FTIR, CD and UV. Although there are some relatively minor comments on the paper, the main point that needs to be reviewed by the authors is the result of FTIR measurements. Based on the data provided in the text (there is no figure), the protein sample is not in its native state, which makes the data inconvenient to be used in drawing conclusions. Authors are kindly requested to take another look at the FTIR experiments.

  16. Interaction of fisetin with human serum albumin by fluorescence, circular dichroism spectroscopy and DFT calculations: binding parameters and conformational changes

    Energy Technology Data Exchange (ETDEWEB)

    Matei, Iulia; Ionescu, Sorana [Department of Physical Chemistry, Faculty of Chemistry, University of Bucharest, Bd. Regina Elisabeta 4-12, 030018 Bucharest (Romania); Hillebrand, Mihaela, E-mail: mihh@gw-chimie.math.unibuc.ro [Department of Physical Chemistry, Faculty of Chemistry, University of Bucharest, Bd. Regina Elisabeta 4-12, 030018 Bucharest (Romania)

    2011-08-15

    The interaction between fisetin, an antioxidant and neuroprotective flavonoid, and human serum albumin (HSA) is investigated by means of fluorescence (steady-state, synchronous, time-resolved) and circular dichroism (CD) spectroscopy. The formation of a 1:1 complex with a constant of about 10{sup 5} M{sup -1} was evidenced. Foerster's resonance energy transfer and competitive binding with site markers warfarin and ibuprofen were considered and discussed. Changes in the CD band of HSA indicate a decrease in the {alpha}-helix content upon binding. An induced CD signal for bound fisetin was observed and rationalized in terms of density functional theory calculations. - Highlights: > Fisetin-BSA system was studied by fluorescence spectroscopy. > Binding parameters, association constant and number of sites were estimated. > Binding site of fisetin was identified by competitive experiments. > Conformational changes in HSA and fisetin were evidenced by circular dichroism. > TDDFT calculated CD spectra supported the experimental data.

  17. Characterization of the interactions of human serum albumin (HSA), gatifloxacin, and metronidazole using spectroscopic and electrochemical methods

    International Nuclear Information System (INIS)

    Fu, Li; Liu, Xiu-fen; Zhou, Qiu-xiang; Zhang, Ji-xiang; Dong, Jing-ya; Wang, Jian-fang

    2014-01-01

    Human serum albumin (HSA), the most abundant protein in blood plasma, is an important carrier for many drugs. Understanding HSA-drug interactions is critical in being able to interpret the distribution and acting mechanisms of these drugs, which is particularly important in the case of multi-drug therapy. In this study, we investigated the interactions between HSA and two commonly used antibiotics, gatifloxacin (GFLX) and metronidazole (MET), in Tris–HCl buffer solution (pH=7.4). The efficacy of the individual drugs (GFLX or MET) and the efficacy of a combination of GFLX and MET were measured using fluorescence spectroscopy, UV absorption spectroscopy, and electrochemical methods. Our results demonstrated that GFLX and MET have a synergistic effect. Briefly, one drug decreased the binding stability with HSA of the other drug, thus increasing the concentration of free drug at the action sites. The interaction of drugs with HSA is a process of complex-formation static quenching. There is approximately one binding site between HSA and the drug (GFLX or MET). The binding distance, r, between the drug and HSA was determined on the basis of the theory of Forster-type non-radiative energy transfer. It was shown that the interaction between the two drugs increased the r-value. Using thermodynamic parameters, we found that the binding of drug-HSA interactions is mainly controlled by electrostatic force. Analysis of the synchronous fluorescence spectrum suggested that the interactions between the drugs have important effects on protein conformation. In conclusion, combining GFLX and MET enhances treatment efficacy. Our study provides a basis to understand the mechanism of the interaction of MET, GFLX and HSA in the human body. - Highlights: • The synergistic effects between MET and GFLX were founed. • The type of interaction between the drugs and HSA was identified

  18. Characterization of the interactions of human serum albumin (HSA), gatifloxacin, and metronidazole using spectroscopic and electrochemical methods

    Energy Technology Data Exchange (ETDEWEB)

    Fu, Li, E-mail: fuli668@126.com; Liu, Xiu-fen; Zhou, Qiu-xiang; Zhang, Ji-xiang; Dong, Jing-ya; Wang, Jian-fang

    2014-05-01

    Human serum albumin (HSA), the most abundant protein in blood plasma, is an important carrier for many drugs. Understanding HSA-drug interactions is critical in being able to interpret the distribution and acting mechanisms of these drugs, which is particularly important in the case of multi-drug therapy. In this study, we investigated the interactions between HSA and two commonly used antibiotics, gatifloxacin (GFLX) and metronidazole (MET), in Tris–HCl buffer solution (pH=7.4). The efficacy of the individual drugs (GFLX or MET) and the efficacy of a combination of GFLX and MET were measured using fluorescence spectroscopy, UV absorption spectroscopy, and electrochemical methods. Our results demonstrated that GFLX and MET have a synergistic effect. Briefly, one drug decreased the binding stability with HSA of the other drug, thus increasing the concentration of free drug at the action sites. The interaction of drugs with HSA is a process of complex-formation static quenching. There is approximately one binding site between HSA and the drug (GFLX or MET). The binding distance, r, between the drug and HSA was determined on the basis of the theory of Forster-type non-radiative energy transfer. It was shown that the interaction between the two drugs increased the r-value. Using thermodynamic parameters, we found that the binding of drug-HSA interactions is mainly controlled by electrostatic force. Analysis of the synchronous fluorescence spectrum suggested that the interactions between the drugs have important effects on protein conformation. In conclusion, combining GFLX and MET enhances treatment efficacy. Our study provides a basis to understand the mechanism of the interaction of MET, GFLX and HSA in the human body. - Highlights: • The synergistic effects between MET and GFLX were founed. • The type of interaction between the drugs and HSA was identified.

  19. Investigation of the Interaction between Patulin and Human Serum Albumin by a Spectroscopic Method, Atomic Force Microscopy, and Molecular Modeling

    Directory of Open Access Journals (Sweden)

    Li Yuqin

    2014-01-01

    Full Text Available The interaction of patulin with human serum albumin (HSA was studied in vitro under normal physiological conditions. The study was performed using fluorescence, ultraviolet-visible spectroscopy (UV-Vis, circular dichroism (CD, atomic force microscopy (AFM, and molecular modeling techniques. The quenching mechanism was investigated using the association constants, the number of binding sites, and basic thermodynamic parameters. A dynamic quenching mechanism occurred between HSA and patulin, and the binding constants (K were 2.60 × 104, 4.59 × 104, and 7.01 × 104 M−1 at 288, 300, and 310 K, respectively. Based on fluorescence resonance energy transfer, the distance between the HSA and patulin was determined to be 2.847 nm. The ΔG0, ΔH0, and ΔS0 values across various temperatures indicated that hydrophobic interaction was the predominant binding force. The UV-Vis and CD results confirmed that the secondary structure of HSA was altered in the presence of patulin. The AFM results revealed that the individual HSA molecule dimensions were larger after interaction with patulin. In addition, molecular modeling showed that the patulin-HSA complex was stabilized by hydrophobic and hydrogen bond forces. The study results suggested that a weak intermolecular interaction occurred between patulin and HSA. Overall, the results are potentially useful for elucidating the toxigenicity of patulin when it is combined with the biomolecular function effect, transmembrane transport, toxicological, testing and other experiments.

  20. The interaction of 2-mercaptobenzimidazole with human serum albumin as determined by spectroscopy, atomic force microscopy and molecular modeling.

    Science.gov (United States)

    Li, Yuqin; Jia, Baoxiu; Wang, Hao; Li, Nana; Chen, Gaopan; Lin, Yuejuan; Gao, Wenhua

    2013-04-01

    The interaction of 2-mercaptobenzimidazole (MBI) with human serum albumin (HSA) was studied in vitro by equilibrium dialysis under normal physiological conditions. This study used fluorescence, ultraviolet-visible spectroscopy (UV-vis), Fourier transform infrared (FT-IR), circular dichroism (CD) and Raman spectroscopy, atomic force microscopy (AFM) and molecular modeling techniques. Association constants, the number of binding sites and basic thermodynamic parameters were used to investigate the quenching mechanism. Based on the fluorescence resonance energy transfer, the distance between the HSA and MBI was 2.495 nm. The ΔG(0), ΔH(0), and ΔS(0) values across temperature indicated that the hydrophobic interaction was the predominant binding Force. The UV, FT-IR, CD and Raman spectra confirmed that the HSA secondary structure was altered in the presence of MBI. In addition, the molecular modeling showed that the MBI-HSA complex was stabilized by hydrophobic forces, which resulted from amino acid residues. The AFM results revealed that the individual HSA molecule dimensions were larger after interaction with MBI. Overall, this study suggested a method for characterizing the weak intermolecular interaction. In addition, this method is potentially useful for elucidating the toxigenicity of MBI when it is combined with the biomolecular function effect, transmembrane transport, toxicological testing and other experiments. Copyright © 2012 Elsevier B.V. All rights reserved.

  1. Spectroscopic studies on the interaction of bovine serum albumin with Ginkgol C15:1 from Ginkgo biloba L

    Energy Technology Data Exchange (ETDEWEB)

    Fang, Yang-Yang [School of Food and Biological Engineering, Jiangsu University, Zhenjiang 212013 (China); School of Chemistry and Chemical Engineering, Jiangsu University, Zhenjiang 212013 (China); Yang, Xiao-Ming, E-mail: XM_Yang1963@126.com [School of Food and Biological Engineering, Jiangsu University, Zhenjiang 212013 (China); Li, Yue-Ying [School of Medical Science and Laboratory Medicine, Jiangsu University, Zhenjiang 212013 (China); Feng, Chun-Lai [School of Pharmacy, Jiangsu University, Zhenjiang 212013 (China)

    2015-06-15

    The interaction between Ginkgol C15:1 (Ginkgol), a natural bioactive compound from Ginkgo biloba, and bovine serum albumin (BSA) was studied by fluorescence, UV–vis absorption, Fourier transform infrared (FT-IR) and circular dichroism (CD) spectroscopy under simulative physiological conditions. The results showed that the fluorescence quenching of BSA by Ginkgol was a static quenching procedure through forming a 1:1 ground-state Ginkgol–BSA complex with a binding constant of about 2.6×10{sup 3} L mol{sup −1}. The values of the thermodynamic parameters indicated that electrostatic and hydrophobic forces played important roles in the interaction of BSA with Ginkgol. The binding distance between BSA and Ginkgol was 3.37 nm, based on Föster’s non-radiative energy transfer theory, and subdomain IIA (Sudlow site I) was the primary binding site which was consistent with that results of molecular docking modeling. The results of UV–vis, CD, three-dimensional fluorescence and FT-IR spectra indicated that binding of Ginkgol to BSA induced conformational changes of BSA. - Highlights: • This is the first time to report the interaction between Ginkgol C15:1 and BSA. • Researching the binding properties of Ginkgol C15:1 and BSA in-depth. • From the aspect of BSA structure change, verified the anticancer activity of Ginkgol. • Molecular docking study explored the interaction of Ginkgol on BSA.

  2. Human serum albumin interactions with C60 fullerene studied by spectroscopy, small-angle neutron scattering, and molecular dynamics simulations

    Science.gov (United States)

    Li, Song; Zhao, Xiongce; Mo, Yiming; Cummings, Peter T.; Heller, William T.

    2013-07-01

    Concern about the toxicity of engineered nanoparticles, such as the prototypical nanomaterial C60 fullerene, continues to grow. While, evidence continues to mount that C60 and its derivatives may pose health hazards, the specific molecular interactions of these particles with biological macromolecules require further investigation. In this article, we report combined experimental and theoretical studies on the interaction of one of the most prevalent proteins in the human body, human serum albumin (HSA), with C60 in an aqueous environment. The C60-HSA interaction was probed by circular dichroism (CD) spectroscopy, small-angle neutron scattering (SANS), and atomistic molecular dynamics (MD) simulations to understand C60-driven changes in the structure of HSA in solution. The CD spectroscopy demonstrates that the secondary structure of the protein decreases in α-helical content in response to the presence of C60 (0.68 nm in diameter). Similarly, C60 produces subtle changes in the solution conformation of HSA (an 8.0 nm × 3.8 nm protein), as evidenced by the SANS data and MD simulations, but the data do not indicate that C60 changes the oligomerization state of the protein, such as by inducing aggregation. The results demonstrate that the interaction is not highly disruptive to the protein in a manner that would prevent it from performing its physiological function.

  3. Human serum albumin interactions with C60 fullerene studied by spectroscopy, small-angle neutron scattering, and molecular dynamics simulations

    International Nuclear Information System (INIS)

    Li, Song; Zhao, Xiongce; Mo, Yiming; Cummings, Peter T.; Heller, William T.

    2013-01-01

    Concern about the toxicity of engineered nanoparticles, such as the prototypical nanomaterial C 60 fullerene, continues to grow. While, evidence continues to mount that C 60 and its derivatives may pose health hazards, the specific molecular interactions of these particles with biological macromolecules require further investigation. In this article, we report combined experimental and theoretical studies on the interaction of one of the most prevalent proteins in the human body, human serum albumin (HSA), with C 60 in an aqueous environment. The C 60 –HSA interaction was probed by circular dichroism (CD) spectroscopy, small-angle neutron scattering (SANS), and atomistic molecular dynamics (MD) simulations to understand C 60 -driven changes in the structure of HSA in solution. The CD spectroscopy demonstrates that the secondary structure of the protein decreases in α-helical content in response to the presence of C 60 (0.68 nm in diameter). Similarly, C 60 produces subtle changes in the solution conformation of HSA (an 8.0 nm × 3.8 nm protein), as evidenced by the SANS data and MD simulations, but the data do not indicate that C 60 changes the oligomerization state of the protein, such as by inducing aggregation. The results demonstrate that the interaction is not highly disruptive to the protein in a manner that would prevent it from performing its physiological function

  4. Interaction of bovine serum albumin with N-acyl amino acid based anionic surfactants: Effect of head-group hydrophobicity.

    Science.gov (United States)

    Ghosh, Subhajit; Dey, Joykrishna

    2015-11-15

    The function of a protein depends upon its structure and surfactant molecules are known to alter protein structure. For this reason protein-surfactant interaction is important in biological, pharmaceutical, and cosmetic industries. In the present work, interactions of a series of anionic surfactants having the same hydrocarbon chain length, but different amino acid head group, such as l-alanine, l-valine, l-leucine, and l-phenylalanine with the transport protein, bovine serum albumin (BSA), were studied at low surfactant concentrations using fluorescence and circular dichroism (CD) spectroscopy, and isothermal titration calorimetry (ITC). The results of fluorescence measurements suggest that the surfactant molecules bind simultaneously to the drug binding site I and II of the protein subdomain IIA and IIIA, respectively. The fluorescence as well as CD spectra suggest that the conformation of BSA goes to a more structured state upon surfactant binding at low concentrations. The binding constants of the surfactants were determined by the use of fluorescence as well as ITC measurements and were compared with that of the corresponding glycine-derived surfactant. The binding constant values clearly indicate a significant head-group effect on the BSA-surfactant interaction and the interaction is mainly hydrophobic in nature. Copyright © 2015 Elsevier Inc. All rights reserved.

  5. Interaction of an antiepileptic drug, lamotrigine with human serum albumin (HSA): Application of spectroscopic techniques and molecular modeling methods.

    Science.gov (United States)

    Poureshghi, Fatemeh; Ghandforoushan, Parisa; Safarnejad, Azam; Soltani, Somaieh

    2017-01-01

    Lamotrigine (an epileptic drug) interaction with human serum albumin (HSA) was investigated by fluorescence, UV-Vis, FTIR, CD spectroscopic techniques, and molecular modeling methods. Binding constant (K b ) of 5.74×10 3 and number of binding site of 0.97 showed that there is a slight interaction between lamotrigine and HSA. Thermodynamic studies was constructed using the flourimetric titrations in three different temperatures and the resulted data used to calculate the parameters using Vant Hoff equation. Decreased Stern Volmer quenching constant by enhanced temperature revealed the static quenching mechanism. Negative standard enthalpy (ΔH) and standard entropy (ΔS) changes indicated that van der Waals interactions and hydrogen bonds were dominant forces which facilitate the binding of Lamotrigine to HSA, the results were confirmed by molecular docking studies which showed no hydrogen binding. The FRET studies showed that there is a possibility of energy transfer between Trp214 and lamotrigine. Also the binding of lamotrigine to HSA in the studied concentrations was not as much as many other drugs, but the secondary structure of the HSA was significantly changed following the interaction in a way that α-helix percentage was reduced from 67% to 57% after the addition of lamotrigine in the molar ratio of 4:1 to HSA. According to the docking studies, lamotrigine binds to IB site preferably. Copyright © 2016. Published by Elsevier B.V.

  6. Insight into the Interaction between the HIV-1 Integrase Inhibitor Elvitegravir and Bovine Serum Albumin: A Spectroscopic Study

    Directory of Open Access Journals (Sweden)

    Ali Saber Abdelhameed

    2015-01-01

    Full Text Available The interaction between the anti-HIV drug Elvitegravir (EVG and bovine serum albumin (BSA was investigated by fluorescence spectroscopy and UV-visible absorption spectra. The mechanism for quenching the fluorescence of BSA by EVG is discussed. It was found that EVG can quench the intrinsic fluorescence of BSA through a static quenching procedure. The quenching type, association constant, and number of binding sites were investigated. The binding constant of EVG with BSA was calculated at different temperatures based on fluorescence quenching results. The thermodynamic parameters ΔHθ, ΔGθ, and ΔSθ were determined. The positive ΔSθ and negative ΔHθ and ΔGθ values showed that a spontaneous interaction may involve both roles of hydrophobic interaction and hydrogen bonding. The interaction of BSA with EVG was also confirmed by UV absorption spectra. The average distance, r, between donor (BSA and acceptor (EVG was obtained according to Förster’s theory of nonradiation energy transfer. Synchronous fluorescence and three-dimensional fluorescence spectra were used to investigate the conformational change of BSA molecules that occur upon addition of EVG and showed, upon binding, a possibility of increasing hydrophobicity around tryptophan residues of BSA.

  7. Biophysical and molecular docking insight into the interaction of cytosine β-D arabinofuranoside with human serum albumin

    Energy Technology Data Exchange (ETDEWEB)

    Alam, Parvez; Chaturvedi, Sumit Kumar [Interdisciplinary Biotechnology Unit, Aligarh Muslim University, Aligarh 202002, UP (India); Anwar, Tamanna [Center of Bioinformatics Research and Technology, Aligarh 202002 (India); Siddiqi, Mohammad Khursheed; Ajmal, Mohd Rehan [Interdisciplinary Biotechnology Unit, Aligarh Muslim University, Aligarh 202002, UP (India); Badr, Gamal [Laboratory of Immunology & Molecular Physiology, Zoology Department, Faculty of Science, Assiut University, 71516 Assiut (Egypt); Mahmoud, Mohamed H. [Food Science and Nutrition Department, National Research Center, Dokki, Cairo (Egypt); Deanship of Scientific Research, King Saud University, Riyadh (Saudi Arabia); Hasan Khan, Rizwan, E-mail: rizwanhkhan@hotmail.com [Interdisciplinary Biotechnology Unit, Aligarh Muslim University, Aligarh 202002, UP (India)

    2015-08-15

    Interaction of pharmacologically important anticancer drug cytosine β-D arabinofuranoside with human serum albumin (HSA) at physiological pH 7.4 has been studied by utilizing various spectroscopic and molecular docking strategies. Fluorescence results revealed that cytosine β-D arabinofuranoside interacts with HSA through static quenching mechanism with binding affinity of 2.4×10{sup 3} M{sup −1}. The average binding distance between drug and Trp{sup 214} of HSA was found to be 2.23 nm on the basis of the theory of Förster's energy transfer. Synchronous fluorescence data indicated that interaction of drug with HSA changed the microenvironment around the tryptophan residue. UV–visible spectroscopy and circular dichroism results deciphered the complex formation and conformational alterations in the HSA respectively. Dynamic light scattering was utilized to understand the topology of protein in absence and presence of drug. Thermodynamic parameters obtained from isothermal titration calorimetry (ΔH=−26.01 kJ mol{sup −1} and TΔS=6.5 kJ mol{sup −1}) suggested the involvement of van der Waal interaction and hydrogen bonding. Molecular docking and displacement study with site specific markers suggested that cytosine β-D arabinofuranoside binds to subdomain IB of HSA which is also known as the hemin binding site. This study will be helpful to understand the binding mechanism of cytosine β-D arabinofuranoside with HSA and associated alterations. - Highlights: • Comprehensive insight into the interaction of CBDA with HSA. • The interaction process is spontaneous and exothermic. • The main governing forces for stabilizing HSA–CBDA complex are van der Waal interaction and hydrogen bonding. • CBDA binds at subdomain IB on HSA.

  8. Biophysical and molecular docking insight into the interaction of cytosine β-D arabinofuranoside with human serum albumin

    International Nuclear Information System (INIS)

    Alam, Parvez; Chaturvedi, Sumit Kumar; Anwar, Tamanna; Siddiqi, Mohammad Khursheed; Ajmal, Mohd Rehan; Badr, Gamal; Mahmoud, Mohamed H.; Hasan Khan, Rizwan

    2015-01-01

    Interaction of pharmacologically important anticancer drug cytosine β-D arabinofuranoside with human serum albumin (HSA) at physiological pH 7.4 has been studied by utilizing various spectroscopic and molecular docking strategies. Fluorescence results revealed that cytosine β-D arabinofuranoside interacts with HSA through static quenching mechanism with binding affinity of 2.4×10 3 M −1 . The average binding distance between drug and Trp 214 of HSA was found to be 2.23 nm on the basis of the theory of Förster's energy transfer. Synchronous fluorescence data indicated that interaction of drug with HSA changed the microenvironment around the tryptophan residue. UV–visible spectroscopy and circular dichroism results deciphered the complex formation and conformational alterations in the HSA respectively. Dynamic light scattering was utilized to understand the topology of protein in absence and presence of drug. Thermodynamic parameters obtained from isothermal titration calorimetry (ΔH=−26.01 kJ mol −1 and TΔS=6.5 kJ mol −1 ) suggested the involvement of van der Waal interaction and hydrogen bonding. Molecular docking and displacement study with site specific markers suggested that cytosine β-D arabinofuranoside binds to subdomain IB of HSA which is also known as the hemin binding site. This study will be helpful to understand the binding mechanism of cytosine β-D arabinofuranoside with HSA and associated alterations. - Highlights: • Comprehensive insight into the interaction of CBDA with HSA. • The interaction process is spontaneous and exothermic. • The main governing forces for stabilizing HSA–CBDA complex are van der Waal interaction and hydrogen bonding. • CBDA binds at subdomain IB on HSA

  9. Interactions of cinnamaldehyde and its metabolite cinnamic acid with human serum albumin and interference of other food additives.

    Science.gov (United States)

    Sun, Qiaomei; Yang, Hongqin; Tang, Peixiao; Liu, Jiuyang; Wang, Wan; Li, Hui

    2018-03-15

    Considering the adverse effect of food additives on humans, thorough research of their physiological effects at the molecular level is important. The interactions of cinnamaldehyde (CNMA), a food perfume, and its major metabolite cinnamic acid (CA) with human serum albumin (HSA) were examined by multiple-spectroscopies. NMR analysis revealed CNMA and CA both bound to HSA, and STD-NMR experiments established CNMA and CA primarily interacted with site I and site II of HSA, respectively. The ligands caused strong quenching of HSA fluorescence through a static quenching mechanism, with hydrophobic and electrostatic interaction between CNMA/CA and HSA, respectively. UV-vis absorption and CD results showed ligands induced secondary structure changes of HSA. Binding configurations were proved by docking method. Furthermore, binding constants of CNMA/CA-HSA systems were influenced by the addition of four other food additives. These studies have increased our knowledge regarding the safety and biological action of CNMA and CA. Copyright © 2017 Elsevier Ltd. All rights reserved.

  10. Study of the interaction between 8-azaguanine and bovine serum albumin using optical spectroscopy and molecular modeling methods.

    Science.gov (United States)

    Gong, Qiao-Ling; Hu, Xin-Gen; Fang, Guo-Yong; Li, Xin-Hua

    2012-02-01

    The interaction between 8-azaguanine (8-Azan) and bovine serum albumin (BSA) in Tris-HCl buffer solutions at pH 7.4 was investigated by means of fluorescence and ultraviolet-visible (UV-Vis) spectroscopy. At 298 K and 310 K, at a wavelength of excitation (λ (ex)) of 282 nm, the fluorescence intensity decreased significantly with increasing concentrations of 8-Azan. Fluorescence static quenching was observed for BSA, which was attributed to the formation of a complex between 8-Azan and BSA during the binding reaction. This was illuminated further by the UV-Vis absorption spectra and the decomposition of the fluorescence spectra. The thermodynamic parameters ∆G, ∆H, ∆S were calculated. The results showed that the forces acting between 8-Azan and BSA were typical hydrophobic forces, and that the interaction process was spontaneous. The interaction distance r between 8-Azan and BSA, evaluated according to fluorescence resonance energy transfer theory, suggested that there is a high possibility of energy transfer from BSA to 8-Azan. Theoretical investigations based on homology modeling and molecular docking suggested that binding between 8-Azan and BSA is dominated by hydrophilic forces and hydrogen bonding. The theoretical investigations provided a good structural basis to explain the phenomenon of fluorescence quenching between 8-Azan and BSA.

  11. Thermodynamic study of the effects of ethanol on the interaction of ochratoxin A with human serum albumin

    Energy Technology Data Exchange (ETDEWEB)

    Li, Yin [Department of General and Physical Chemistry, University of Pécs, Ifjúság 6, H-7624 Pécs (Hungary); János Szentágothai Research Center, Ifjúság 20, H-7624 Pécs (Hungary); Czibulya, Zsuzsanna [Department of General and Physical Chemistry, University of Pécs, Ifjúság 6, H-7624 Pécs (Hungary); János Szentágothai Research Center, Ifjúság 20, H-7624 Pécs (Hungary); Chimie et Biologie des Membranes et Nanoobjets, CNRS-Université de Bordeaux, UMR 52478, ENITAB, Pessac (France); Poór, Miklós [Institute of Laboratory Medicine, University of Pécs, Ifjúság 13, H-7624, Pécs (Hungary); Lecomte, Sophie [Chimie et Biologie des Membranes et Nanoobjets, CNRS-Université de Bordeaux, UMR 52478, ENITAB, Pessac (France); Kiss, László [Department of General and Physical Chemistry, University of Pécs, Ifjúság 6, H-7624 Pécs (Hungary); János Szentágothai Research Center, Ifjúság 20, H-7624 Pécs (Hungary); and others

    2014-04-15

    Ethanol effect on the interaction of ochratoxin A (OTA) with human serum albumin (HSA) was investigated by using fluorescence spectroscopy and Raman spectroscopy. The Raman results showed that after the binding of OTA, the microenvironment of tryptophan residue on HSA became less hydrophobic. The fluorescence quenching observations revealed that the binding constant for the binding of OTA to HSA decreased as ethanol concentration increased. The thermodynamic studies showed that the binding process of OTA to HSA switched from being entropy-driven to enthalpy-driven in the presence of increasing concentrations (0.7–24.7%, vol/vol) of ethanol. Enthalpy–entropy compensation effect for the binding of OTA to HSA in the presence of different ethanol concentrations had been found. Based on the thermodynamic analyses, we concluded that the ethanol-induced variation of the shape of binding site of OTA on HSA and the solvent reorganization surrounding the OTA–HSA complex are the two dominant effects. -- Highlights: • The presence of ethanol can prohibit the binding of OTA to HSA. • Microenvironment of Trp214 on HSA becomes less hydrophobic after the binding of OTA. • Ethanol induces the interaction from being entropy-driven to enthalpy-driven. • Enthalpy–entropy compensation for the interaction was found.

  12. Mechanistic and conformational studies on the interaction of anti-inflammatory drugs, isoxicam and tenoxicam with bovine serum albumin

    Energy Technology Data Exchange (ETDEWEB)

    Punith, Reeta; Katrahalli, Umesha; Kalanur, Shankara S. [Department of Chemistry, Karnatak University, Dharwad 580 003 (India); Jaldappagari, Seetharamappa, E-mail: jseetharam@yahoo.co [Department of Chemistry, Karnatak University, Dharwad 580 003 (India)

    2010-11-15

    The mechanism of interaction of the non-steroidal anti-inflammatory drugs, isoxicam (IXM) and tenoxicam (TXM) with bovine serum albumin (BSA) has been studied using spectroscopic techniques, viz., spectrofluorescence, circular dichroism (CD), UV-visible absorption and FT-IR under simulative physiological conditions. Stern-Volmer analysis of fluorescence quenching data shows the presence of the static quenching mechanism. Thermodynamic parameters (negative {Delta}H{sup 0} and positive {Delta}S{sup 0} values obtained in the present study) revealed that the hydrophobic interactions played a major role in the interaction of these drugs with BSA. The distance, r between the donor (BSA) and acceptor (IXM/TXM) was calculated based on the Forster's theory of non-radiation energy transfer and the values were observed to be 3.85 nm and 2.60 nm in IXM-BSA and TXM-BSA system, respectively. CD and FT-IR studies indicated that the binding of IXM/TXM to BSA induced conformational changes in BSA. The effect of common ions on the binding of IXM/TXM to BSA has been investigated.

  13. Probing into the binding interaction between medroxyprogesterone acetate and bovine serum albumin (BSA): spectroscopic and molecular docking methods.

    Science.gov (United States)

    Fang, Fang; Pan, Dong-Qi; Qiu, Min-Jie; Liu, Ting-Ting; Jiang, Min; Wang, Qi; Shi, Jie-Hua

    2016-09-01

    To further understand the mechanism of action and pharmacokinetics of medroxyprogesterone acetate (MPA), the binding interaction of MPA with bovine serum albumin (BSA) under simulated physiological conditions (pH 7.4) was studied using fluorescence emission spectroscopy, synchronous fluorescence spectroscopy, circular dichroism and molecular docking methods. The experimental results reveal that the fluorescence of BSA quenches due to the formation of MPA-BSA complex. The number of binding sites (n) and the binding constant for MPA-BSA complex are ~1 and 4.6 × 10(3)  M(-1) at 310 K, respectively. However, it can be concluded that the binding process of MPA with BSA is spontaneous and the main interaction forces between MPA and BSA are van der Waals force and hydrogen bonding interaction due to the negative values of ΔG(0) , ΔH(0) and ΔS(0) in the binding process of MPA with BSA. MPA prefers binding on the hydrophobic cavity in subdomain IIIA (site II'') of BSA resulting in a slight change in the conformation of BSA, but BSA retaining the α-helix structure. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

  14. Study of interaction of butyl p-hydroxybenzoate with human serum albumin by molecular modeling and multi-spectroscopic method

    Energy Technology Data Exchange (ETDEWEB)

    Wang Qin, E-mail: wqing07@lzu.c [Department of Chemistry, Lanzhou University, Lanzhou 730000 (China); Zhang Yaheng, E-mail: zhangyah04@lzu.c [Department of Chemistry, Lanzhou University, Lanzhou 730000 (China); Sun Huijun, E-mail: sun.hui.jun-04@163.co [Department of Chemistry, Lanzhou University, Lanzhou 730000 (China); Chen Hongli, E-mail: hlchen@lzu.edu.c [Department of Chemistry, Lanzhou University, Lanzhou 730000 (China); Chen Xingguo, E-mail: chenxg@lzu.edu.c [Department of Chemistry, Lanzhou University, Lanzhou 730000 (China)

    2011-02-15

    Study of the interaction between butyl p-hydroxybenzoate (butoben) and human serum albumin (HSA) has been performed by molecular modeling and multi-spectroscopic method. The interaction mechanism was predicted through molecular modeling first, then the binding parameters were confirmed using a series of spectroscopic methods, including fluorescence spectroscopy, UV-visible absorbance spectroscopy, circular dichroism (CD) spectroscopy and Fourier transform infrared (FT-IR) spectroscopy. The thermodynamic parameters of the reaction, standard enthalpy {Delta}H{sup 0} and entropy {Delta}S{sup 0}, have been calculated to be -29.52 kJ mol{sup -1} and -24.23 J mol{sup -1} K{sup -1}, respectively, according to the Van't Hoff equation, which suggests the van der Waals force and hydrogen bonds are the predominant intermolecular forces in stabilizing the butoben-HSA complex. Results obtained by spectroscopic methods are consistent with that of the molecular modeling study. In addition, alteration of secondary structure of HSA in the presence of butoben was evaluated using the data obtained from UV-visible absorbance, CD and FT-IR spectroscopies. - Research highlights: The interaction between butyl p-hydroxybenzoate with HSA has been investigated for the first time. Molecular modeling study can provide theoretical direction for experimental design. Multi-spectroscopic method can provide the binding parameters and thermodynamic parameters. These results are important for food safety and human health when using parabens as a preservative.

  15. Interaction of Flavonoids from Woodwardia unigemmata with Bovine Serum Albumin (BSA): Application of Spectroscopic Techniques and Molecular Modeling Methods.

    Science.gov (United States)

    Ma, Rui; Pan, Hong; Shen, Tao; Li, Peng; Chen, Yanan; Li, Zhenyu; Di, Xiaxia; Wang, Shuqi

    2017-08-09

    Phytochemical investigation on the methanol extract of Woodwardia unigemmata resulted in the isolation of seven flavonoids, including one new flavonol acylglycoside ( 1 ). The structures of these compounds were elucidated on the basis of extensive spectroscopic analysis and comparison of literature data. The multidrug resistance (MDR) reversing activity was evaluated for the isolated compounds using doxorubicin-resistant K562/A02 cells model. Compound 6 showed comparable MDR reversing effect to verapamil. Furthermore, the interaction between compounds and bovine serum albumin (BSA) was investigated by spectroscopic methods, including steady-state fluorescence, synchronous fluorescence, circular dichroism (CD) spectroscopies, and molecular docking approach. The experimental results indicated that the seven flavonoids bind to BSA by static quenching mechanisms. The negative ΔH and ΔS values indicated that van der Waals interactions and hydrogen bonds contributed in the binding of compounds 2 - 6 to BSA. In the case of compounds 1 and 7 systems, the hydrophobic interactions play a major role. The binding of compounds to BSA causes slight changes in the secondary structure of BSA. There are two binding sites of compound 6 on BSA and site I is the main site according to the molecular docking studies and the site marker competitive binding assay.

  16. Investigation of the interaction of aurantio-obtusin with human serum albumin by spectroscopic and molecular docking methods.

    Science.gov (United States)

    Liu, Jianming; Yan, Xuyang; Yue, Yuanyuan; Zhao, Shufang

    2018-02-01

    The interaction between human serum albumin (HSA) and aurantio-obtusin was investigated by spectroscopic techniques combined with molecular docking. The Stern-Volmer quenching constants (K SV ) decreased from 8.56 × 10 5  M -1 to 5.13 × 10 5  M -1 with a rise in temperatures from 289 to 310 K, indicating that aurantio-obtusin produced a static quenching of the intrinsic fluorescence of HSA. Time-resolved fluorescence studies proved again that the static quenching mechanism was involved in the interaction. The sign and magnitude of the enthalpy change as well as the entropy change suggested involvement of hydrogen bonding and hydrophobic interaction in aurantio-obtusin-HSA complex formation. Aurantio-obtusin binding to HSA produced significant alterations in secondary structures of HSA, as revealed from the time-resolved fluorescence, Fourier transform infrared (FT-IR) spectroscopy, three-dimensional (3D) fluorescence and circular dichroism (CD) spectral results. Molecular docking study and site marker competitive experiment confirmed aurantio-obtusin bound to HSA at site I (subdomain IIA). Copyright © 2017 John Wiley & Sons, Ltd.

  17. Spectroscopic and molecular docking studies of binding interaction of gefitinib, lapatinib and sunitinib with bovine serum albumin (BSA).

    Science.gov (United States)

    Shen, Guo-Feng; Liu, Ting-Ting; Wang, Qi; Jiang, Min; Shi, Jie-Hua

    2015-12-01

    The binding interactions of three kinds of tyrosine kinase inhibitors (TKIs), such as gefitinib, lapatinib and sunitinib, with bovine serum albumin (BSA) were studied using ultraviolet spectrophotometry, fluorescence spectroscopy, circular dichroism (CD), Fourier transform infrared spectroscopy (FT-IR) and molecular docking methods. The experimental results showed that the intrinsic fluorescence quenching of BSA induced by the three TKIs resulted from the formation of stable TKIs-BSA complexes through the binding interaction of TKIs with BSA. The stoichiometry of three stable TKIs-BSA complexes was 1:1 and the binding constants (Kb) of the three TKIs-BSA complexes were in the order of 10(4)M(-1) at 310 K, indicating that there was a strong binding interaction of the three TKIs with BSA. Based on the analysis of the signs and magnitudes of the free energy change (ΔG(0)), enthalpic change (ΔH(0)) and entropic change (ΔS(0)) in the binding process, it can be deduced that the binding process of the three TKIs with BSA was spontaneous and enthalpy-driven process, and the main interaction forces between the three TKIs and BSA were van der Waals force and hydrogen bonding interaction. Moreover, from the results of CD, FT-IR and molecular docking, it can be concluded that there was a significant difference between the three TKIs in the binding site on BSA, lapatinib was located on site II (m) of BSA while gefitinib and sunitinib were bound on site I of BSA, and there were some changes in the BSA conformation when binding three TKIs to BSA but BSA still retains its secondary structure α-helicity. Copyright © 2015 Elsevier B.V. All rights reserved.

  18. Binding interaction of ramipril with bovine serum albumin (BSA): Insights from multi-spectroscopy and molecular docking methods.

    Science.gov (United States)

    Shi, Jie-Hua; Pan, Dong-Qi; Jiang, Min; Liu, Ting-Ting; Wang, Qi

    2016-11-01

    The binding interaction between a typical angiotensin-converting enzyme inhibitor (ACEI), ramipril, and a transport protein, bovine serum albumin (BSA), was studied in vitro using UV-vis absorption spectroscopy, steady-state fluorescence spectroscopic titration, synchronous fluorescence spectroscopy, three dimensional fluorescence spectroscopy, circular dichroism and molecular docking under the imitated physiological conditions (pH=7.4). The experimental results suggested that the intrinsic fluorescence of BSA was quenched by ramipril thought a static quenching mechanism, indicating that the stable ramipril-BSA complex was formed by the intermolecular interaction. The number of binding sites (n) and binding constant of ramipril-BSA complex were about 1 and 3.50×10 4 M -1 at 298K, respectively, suggesting that there was stronger binding interaction of ramipril with BSA. The thermodynamic parameters together with molecular docking study revealed that both van der Waal's forces and hydrogen bonding interaction dominated the formation of the ramipril-BSA complex and the binding interaction of BSA with ramipril is enthalpy-driven processes due to |ΔH°|>|TΔS°| and ΔG°BSA was calculated to be 3.56nm based on Förster's non-radiative energy transfer theory. The results of the competitive displacement experiments and molecular docking confirmed that ramipril inserted into the subdomain IIA (site I) of BSA, resulting in a slight change in the conformation of BSA but BSA still retained its secondary structure α-helicity. Copyright © 2016 Elsevier B.V. All rights reserved.

  19. Spectroscopic study of interaction between osthole and human serum albumin: Identification of possible binding site of the compound

    International Nuclear Information System (INIS)

    Bijari, Nooshin; Shokoohinia, Yalda; Ashrafi-Kooshk, Mohammad Reza; Ranjbar, Samira; Parvaneh, Shahram; Moieni-Arya, Maryam; Khodarahmi, Reza

    2013-01-01

    The studies on the interaction between human serum albumin (HSA) and drugs have been an interesting research field in life science, chemistry and clinical medicine. Osthole possesses a variety of pharmacological activities including anti-tumor, anti-inflammation, anti-seizure, anti-hyperlipidemic and anti-osteoporosis effects. The interaction of osthole with HSA and its binding site in HSA by spectroscopic methods is the subject of this work. By monitoring the intrinsic fluorescence of the single Trp 214 residue and performing site markers displacement measurements, the specific binding of osthole in the vicinity of Sudlow's site I of HSA has been clarified. The changes in the secondary structure of HSA after its complexation with ligand were studied with CD spectroscopy, which indicate that osthole induced only a slight decrease in the helix structural content of the protein. In addition, the mean distance between osthole and HSA fluorophores is estimated to be 4.96 nm using Föster's equation on the basis of the fluorescence energy transfer. Furthermore, the synchronous fluorescence spectra show that the microenvironment of the tryptophan residues does not have obvious changes. Osthole can quench the intrinsic fluorescence of HSA by dynamic quenching, and analysis of the thermodynamic parameters of binding showed that hydrophobic interactions play an important role in the stabilizing of the complex. Increase of protein surface hydrophobicity (PSH) was also observed upon the osthole binding. -- Highlights: • Hydrophobic interactions play an important role in osthole–HSA interaction. • Sudlow's I site is possible binding site of osthole. • Osthole inhibits esterase activity of HSA. • Osthole binding induces no gross protein structural changes

  20. Molecular interaction of 2,4-diacetylphloroglucinol (DAPG) with human serum albumin (HSA): The spectroscopic, calorimetric and computational investigation

    Science.gov (United States)

    Pragna Lakshmi, T.; Mondal, Moumita; Ramadas, Krishna; Natarajan, Sakthivel

    2017-08-01

    Drug molecule interaction with human serum albumin (HSA) affects the distribution and elimination of the drug. The compound, 2,4-diacetylphloroglucinol (DAPG) has been known for its antimicrobial, antiviral, antihelminthic and anticancer properties. However, its interaction with HSA is not yet reported. In this study, the interaction between HSA and DAPG was investigated through steady-state fluorescence, time-resolved fluorescence (TRF), circular dichroism (CD), Fourier transform infrared (FT-IR) spectroscopy, isothermal titration calorimetry (ITC), molecular docking and molecular dynamics simulation (MDS). Fluorescence spectroscopy results showed the strong quenching of intrinsic fluorescence of HSA due to interaction with DAPG, through dynamic quenching mechanism. The compound bound to HSA with reversible and moderate affinity which explained its easy diffusion from circulatory system to target tissue. The thermodynamic parameters from fluorescence spectroscopic data clearly revealed the contribution of hydrophobic forces but, the role of hydrogen bonds was not negligible according to the ITC studies. The interaction was exothermic and spontaneous in nature. Binding with DAPG reduced the helical content of protein suggesting the unfolding of HSA. Site marker fluorescence experiments revealed the change in binding constant of DAPG in the presence of site I (warfarin) but not site II marker (ibuprofen) which confirmed that the DAPG bound to site I. ITC experiments also supported this as site I marker could not bind to HSA-DAPG complex while site II marker was accommodated in the complex. In silico studies further showed the lowest binding affinity and more stability of DAPG in site I than in site II. Thus the data presented in this study confirms the binding of DAPG to the site I of HSA which may help in further understanding of pharmacokinetic properties of DAPG.

  1. Biophysical study on the interaction between two palladium(II) complexes and human serum albumin by Multispectroscopic methods

    Energy Technology Data Exchange (ETDEWEB)

    Saeidifar, Maryam, E-mail: saeidifar@merc.ac.ir [Department of Nanotechnology and Advanced Materials, Materials and Energy Research Center, Karaj (Iran, Islamic Republic of); Mansouri-Torshizi, Hassan [Department of Chemistry, University of Sistan and Baluchestan, Zahedan (Iran, Islamic Republic of); Akbar Saboury, Ali [Institute of Biochemistry and Biophysics, University of Tehran, Tehran (Iran, Islamic Republic of)

    2015-11-15

    The interaction of [Pd(bpy)(n-pr-dtc)]Br (I) and ([Pd(phen)(n-pr-dtc)]Br (II) (bpy=2,2′-bipyridine, phen=1,10-phenanthroline and n-pr-dtc=n-propyldithiocarbamate) with human serum albumin (HSA) was investigated using fluorescence, UV–vis absorption and circular dichroism (CD) spectroscopy techniques under simulative physiological conditions (pH=7.4). It was observed that the two complexes interact with HSA via static fluorescence quenching. The thermodynamic parameters indicate that the binding process was spontaneous and that hydrogen bonds and van der Waals forces play a major role in the association of the HSA–Pd(II) complexes. The activation energy (E{sub a}), binding constant (K{sub b}) and number of binding sites (n) of the HSA–Pd(II) complexes were calculated from fluorescence data at 293 K, 303 K and 311 K. The conformational alternations of protein secondary structure in the presence of Pd(II) complexes were demonstrated using synchronous fluorescence, three-dimensional fluorescence spectra, UV–vis absorption and circular dichroism techniques. Furthermore, the apparent distance between donor (HSA) and acceptor (Pd(II) complexes) was determined using fluorescence resonance energy transfer (FRET). The binding studies between these complexes and HSA give us key insights into the transportation, distribution and toxicity of newly design antitumor Pd(II) complexes in human blood. - Highlights: • The HSA binding properties of two Palladium (II) complexes were studied. • Static quenching mechanism is effective in the interaction of HSA with Pd(II) complexes. • Hydrogen bonds and van der Waals forces were involved in the Pd(II) complexes–HSA interaction. • 3D fluorescence was used to study the interaction between two complexes and HSA.

  2. Spectroscopic study of interaction between osthole and human serum albumin: Identification of possible binding site of the compound

    Energy Technology Data Exchange (ETDEWEB)

    Bijari, Nooshin [Medical Biology Research Center, Kermanshah University of Medical Sciences, Kermanshah (Iran, Islamic Republic of); Shokoohinia, Yalda [Department of Pharmacognosy and Biotechnology, Faculty of Pharmacy, Kermanshah University of Medical Sciences, Kermanshah (Iran, Islamic Republic of); Ashrafi-Kooshk, Mohammad Reza; Ranjbar, Samira; Parvaneh, Shahram [Medical Biology Research Center, Kermanshah University of Medical Sciences, Kermanshah (Iran, Islamic Republic of); Moieni-Arya, Maryam [Student Research Committee, Faculty of Pharmacy, Kermanshah University of Medical Sciences, Kermanshah (Iran, Islamic Republic of); Khodarahmi, Reza, E-mail: rkhodarahmi@mbrc.ac.ir [Medical Biology Research Center, Kermanshah University of Medical Sciences, Kermanshah (Iran, Islamic Republic of); Department of Pharmacognosy and Biotechnology, Faculty of Pharmacy, Kermanshah University of Medical Sciences, Kermanshah (Iran, Islamic Republic of)

    2013-11-15

    The studies on the interaction between human serum albumin (HSA) and drugs have been an interesting research field in life science, chemistry and clinical medicine. Osthole possesses a variety of pharmacological activities including anti-tumor, anti-inflammation, anti-seizure, anti-hyperlipidemic and anti-osteoporosis effects. The interaction of osthole with HSA and its binding site in HSA by spectroscopic methods is the subject of this work. By monitoring the intrinsic fluorescence of the single Trp{sub 214} residue and performing site markers displacement measurements, the specific binding of osthole in the vicinity of Sudlow's site I of HSA has been clarified. The changes in the secondary structure of HSA after its complexation with ligand were studied with CD spectroscopy, which indicate that osthole induced only a slight decrease in the helix structural content of the protein. In addition, the mean distance between osthole and HSA fluorophores is estimated to be 4.96 nm using Föster's equation on the basis of the fluorescence energy transfer. Furthermore, the synchronous fluorescence spectra show that the microenvironment of the tryptophan residues does not have obvious changes. Osthole can quench the intrinsic fluorescence of HSA by dynamic quenching, and analysis of the thermodynamic parameters of binding showed that hydrophobic interactions play an important role in the stabilizing of the complex. Increase of protein surface hydrophobicity (PSH) was also observed upon the osthole binding. -- Highlights: • Hydrophobic interactions play an important role in osthole–HSA interaction. • Sudlow's I site is possible binding site of osthole. • Osthole inhibits esterase activity of HSA. • Osthole binding induces no gross protein structural changes.

  3. Relevance of Orbital Interactions and Pauli Repulsion in the Metal-Metal Bond of Coinage Metals.

    Science.gov (United States)

    Brands, Maria B; Nitsch, Jörn; Guerra, Célia Fonseca

    2018-03-05

    The importance of relativity and dispersion in metallophilicity has been discussed in numerous studies. The existence of hybridization in the bonding between closed shell d 10 -d 10 metal atoms has also been speculated, but the presence of attractive MO interaction in the metal-metal bond is still a matter of an ongoing debate. In this comparative study, a quantitative molecular orbital analysis and energy decomposition is carried out on the metallophilic interaction in atomic dimers (M + ···M + ) and molecular perpendicular [H 3 P-M-X] 2 (where M = Cu, Ag, and Au; X = F, Cl, Br, and I). Our computational studies prove that besides the commonly accepted dispersive interactions, orbital interactions and Pauli repulsion also play a crucial role in the strength and length of the metal-metal bond. Although for M + ···M + the orbital interaction is larger than the Pauli repulsion, leading to a net attractive MO interaction, the bonding mechanism in perpendicular [H 3 P-M-X] dimers is different due to the larger separation between the donor and acceptor orbitals. Thus, Pauli repulsion is much larger, and two-orbital, four-electron repulsion is dominant.

  4. Interaction mechanisms of ionic liquids [Cnmim]Br (n=4, 6, 8, 10) with bovine serum albumin

    International Nuclear Information System (INIS)

    Yan Hua; Wu Junyong; Dai Guoliang; Zhong Aiguo; Chen Hao; Yang Jianguo; Han Deman

    2012-01-01

    It is important to study the interaction of ionic liquids (ILs) with protein for the applications of ILs in biochemical process, and help the researchers to choose and design the better ILs to serve as a solvent. In this work, the interaction between 1-alkyl-3-methylimidazolium bromide [C n mim]Br (n=4, 6, 8, 10) and bovine serum albumin (BSA) was systematically investigated for the first time by multi-spectroscopic approach (fluorescence, UV–vis and FT-IR spectroscopy) and density functional theory (DFT). [C n mim]Br (n=4, 6, 8, 10) can bind to BSA by H-bond interaction between their cationic headgroups and Asp/Glu amino acid residue at the surface of BSA, and hydrophobic interaction between their hydrocarbon chains and the hydrophobic amino acid residues in the interior of BSA. On the basis of thermodynamic parameters and the similar structure of [C n mim]Br (n=4, 6, 8, 10), it can be inferred that the hydrophobic interaction plays a major role in the interaction of [C 10 mim]Br with BSA, while the hydrogen bond and van der Waals force play a major role in the interaction of [C n mim]Br (n=4, 6, 8) with BSA. Synchronous fluorescence and FT-IR spectra indicate that [C 10 mim]Br could markedly change the secondary structure of BSA, while [C n mim]Br (n=4, 6, 8) could slightly change the secondary structure of BSA. The results allowed us to understand (i) the effect of the alkyl chain length of the cation on the mechanism of ILs–protein interaction and (ii) the effect of the alkyl chain length of the cation on the protein secondary structure. - Highlights: ► Interaction of [C n mim]Br with BSA was investigated by spectroscopy and DFT. ► Interaction mechanisms and BSA secondary structure were discussed. ► Effects of the alkyl chain length of cation were presented.

  5. Study on the interaction of tussilagone with human serum albumin (HSA) by spectroscopic and molecular docking techniques

    Science.gov (United States)

    Xu, Liang; Hu, Yan-Xi; Li, Yan-Cheng; Zhang, Li; Ai, Hai-Xin; Liu, Hong-Sheng; Liu, Yu-Feng; Sang, Yu-Li

    2017-12-01

    Tussilagone is a sesquiterpenoid which exhibits a variety of pharmacological activities. The interaction of tussilagone with human serum albumin (HSA) was investigated using fluorescence spectroscopy, UV-vis absorption, fluorescence probe experiments, synchronous fluorescence, circular dichroism (CD) spectra, three-dimensional spectra and molecular docking techniques under simulative physiological conditions. The results clarified that the fluorescence quenching of HSA by tussilagone was a static quenching process as a result of HSA-tussilagone (1:1) complex. Tussilagone spontaneously bound to HSA in site I (subdomain IIA), which was primarily driven by hydrophobic forces and hydrogen bonds (ΔH° = -13.89 kJ mol-1, ΔS° = 16.39 J mol-1 K-1). The binding constant was calculated to be 2.182 × 103 L mol-1 and the binding distance was estimated to be 2.07 nm at 291 K, showing the occurrence of fluorescence energy transfer. The results of CD, synchronous and three-dimensional fluorescence spectra all revealed that tussilagone induced the conformational changes of HSA. Meanwhile, the study of molecular docking also indicated that tussilagone could bind to the site I of HSA mainly by hydrophobic and hydrogen bond interactions.

  6. Analysis of interactions of brevetoxin-B and human serum albumin by liquid chromatography/mass spectrometry.

    Science.gov (United States)

    Wang, Zhihong; Ramsdell, John S

    2011-01-14

    Brevetoxins are neurotoxins produced by marine dinoflagellates, primarily Karenia brevis, and can cause intoxication and even mortality of marine species, affect human health through the consumption of brevetoxin-contaminated shellfish, and effect respiratory irritation through aerosol exposure at coastal areas. Brevetoxin-A and brevetoxin-B, the major brevetoxins produced in algae, are metabolized to a series of amino acid and peptide-related derivatives in shellfish through the reactions of the amino acid residue cysteine with an α,β-unsaturated aldehyde group. In this paper, covalent interactions between brevetoxin and proteins were investigated using brevetoxin-B and human serum albumin (HSA) as a model. It is demonstrated that both noncovalent and covalent interactions can occur between brevetoxin-B and HSA with in vitro experiments. Covalent adducts of brevetoxin-B and HSA were generated under physiological conditions and reduced with sodium borohydride based on the reaction conditions of single amino acid residues with brevetoxin-B. LC/MS analysis of toxin-treated HSA recognized the formation of the intact protein adducts with primarily one and two toxin molecules attached to one HSA molecule. HSA treated with/without brevetoxin-B was digested with trypsin, trypsin following chymotrypsin, and Pronase, respectively, for LC/MS analysis of adduction sites. Brevetoxin-B was found to react primarily with Cys(34) and His(3) and with His and Lys at other sites of HSA with variable reactivity and with Lys in general the least reactive.

  7. Structure dependent hydrophobic and hydrophilic interactions between nickel(II) Schiff base complexes and serum albumins: Spectroscopic and docking studies

    International Nuclear Information System (INIS)

    Koley Seth, Banabithi; Ray, Aurkie; Banerjee, Mousumi; Bhattacharyya, Teerna; Bhattacharyya, Dhananjay; Basu, Samita

    2016-01-01

    A systematic and comparative binding study between serum-albumins (SA) and a series of monomeric nickel(II)-Schiff-base-complexes (NSCs), which might be imperative to investigate the function of SA behind nickel allergy, has been carried out through docking and different spectroscopic techniques. The initial docking studies indicate structure-dependent selective hydrophobic and hydrophilic interactions. The pyridine and phenyl containing NSCs, which are more aromatic, show better π–π staking compared to pyrrole one. Again all the NSCs bind with BSA though amino acid residues of IB domain affecting local environment of the Trp-134 surrounded by both hydrophobic and hydrophilic residues instead of the hydrophobically buried Trp-212. In HSA the hydophobically buried Trp-214 is influenced by NSCs. The experimental results nicely support the docking outcomes. The changes in Gibbs free energy, binding affinity and the nature of hydrophilic/hydrophobic interactions of NSC–SA systems indicate greater accessibility of N_2O_2 donor set complex compared to N_4 one towards SA. Quantum chemical structure optimizations support the better planarity of NSC with N_2O_2 which provides better binding. Therefore the structural variation of N_2O_2 donor set complexes becomes much more useful compared to N_4 one to search out the most compatible NSC towards SAs.

  8. Structure dependent hydrophobic and hydrophilic interactions between nickel(II) Schiff base complexes and serum albumins: Spectroscopic and docking studies

    Energy Technology Data Exchange (ETDEWEB)

    Koley Seth, Banabithi; Ray, Aurkie; Banerjee, Mousumi; Bhattacharyya, Teerna [Chemical Sciences Division, Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Kolkata 700064 (India); Bhattacharyya, Dhananjay [Computational Sciences Division, Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Kolkata 700064 (India); Basu, Samita, E-mail: samita.basu@saha.ac.in [Chemical Sciences Division, Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Kolkata 700064 (India)

    2016-03-15

    A systematic and comparative binding study between serum-albumins (SA) and a series of monomeric nickel(II)-Schiff-base-complexes (NSCs), which might be imperative to investigate the function of SA behind nickel allergy, has been carried out through docking and different spectroscopic techniques. The initial docking studies indicate structure-dependent selective hydrophobic and hydrophilic interactions. The pyridine and phenyl containing NSCs, which are more aromatic, show better π–π staking compared to pyrrole one. Again all the NSCs bind with BSA though amino acid residues of IB domain affecting local environment of the Trp-134 surrounded by both hydrophobic and hydrophilic residues instead of the hydrophobically buried Trp-212. In HSA the hydophobically buried Trp-214 is influenced by NSCs. The experimental results nicely support the docking outcomes. The changes in Gibbs free energy, binding affinity and the nature of hydrophilic/hydrophobic interactions of NSC–SA systems indicate greater accessibility of N{sub 2}O{sub 2} donor set complex compared to N{sub 4} one towards SA. Quantum chemical structure optimizations support the better planarity of NSC with N{sub 2}O{sub 2} which provides better binding. Therefore the structural variation of N{sub 2}O{sub 2} donor set complexes becomes much more useful compared to N{sub 4} one to search out the most compatible NSC towards SAs.

  9. Using resonance light scattering and UV/vis absorption spectroscopy to study the interaction between gliclazide and bovine serum albumin.

    Science.gov (United States)

    Zhang, Qiu-Ju; Liu, Bao-Sheng; Li, Gai-Xia; Han, Rong

    2016-08-01

    At different temperatures (298, 310 and 318 K), the interaction between gliclazide and bovine serum albumin (BSA) was investigated using fluorescence quenching spectroscopy, resonance light scattering spectroscopy and UV/vis absorption spectroscopy. The first method studied changes in the fluorescence of BSA on addition of gliclazide, and the latter two methods studied the spectral change in gliclazide while BSA was being added. The results indicated that the quenching mechanism between BSA and gliclazide was static. The binding constant (Ka ), number of binding sites (n), thermodynamic parameters, binding forces and Hill's coefficient were calculated at three temperatures. Values for the binding constant obtained using resonance light scattering and UV/vis absorption spectroscopy were much greater than those obtained from fluorescence quenching spectroscopy, indicating that methods monitoring gliclazide were more accurate and reasonable. In addition, the results suggest that other residues are involved in the reaction and the mode 'point to surface' existed in the interaction between BSA and gliclazide. Copyright © 2015 John Wiley & Sons, Ltd. Copyright © 2015 John Wiley & Sons, Ltd.

  10. Interaction between titanium dioxide nanoparticles and human serum albumin revealed by fluorescence spectroscopy in the absence of photoactivation

    Energy Technology Data Exchange (ETDEWEB)

    Sun Wen [Department of Analytical Chemistry, China Pharmaceutical University, Nanjing 210009 (China); Du Yingxiang, E-mail: du_yingxiang@126.co [Key Laboratory of Drug Quality Control and Pharmacovigilance, Ministry of Education, China Pharmaceutical University, No. 24, Tongjiaxiang, Nanjing, Jiangsu 210009 (China) and Department of Analytical Chemistry, China Pharmaceutical University, Nanjing 210009 (China); Chen Jianqiu [Department of Analytical Chemistry, China Pharmaceutical University, Nanjing 210009 (China); Kou Junping; Yu Boyang [Department of Complex Prescription of TCM, China Pharmaceutical University, Nanjing 210009 (China)

    2009-08-15

    Titanium dioxide (TiO{sub 2}) nanoparticles (NPs) are widely used as an important kind of biomaterials. The interaction between TiO{sub 2} (P25) at 20 nm in diameter and human serum albumin (HSA) was studied by fluorescence spectroscopy in this work. Under the simulative physiological conditions, fluorescence data revealed the presence of a single class of binding site on HSA and its binding constants (K{sub a}) were 2.18+-0.04x10{sup 4}, 0.87+-0.05x10{sup 4}, 0.68+-0.06x10{sup 4} M{sup -1} at 298, 304 and 310 K, respectively. In addition, according to the Van't Hoff equation, the thermodynamic functions standard enthalpy (DELTAH{sup 0}) and standard entropy (DELTAS{sup 0}) for the reaction were calculated to be -75.18+-0.15 kJ mol{sup -1} and -170.11+-0.38 J mol{sup -1} K{sup -1}. These results indicated that TiO{sub 2} NPs bond to HSA mainly by van der Waals force and hydrogen bonding formation in low dielectric media, and the electrostatic interactions cannot be excluded. Furthermore, the effects of common ions on the binding constant of TiO{sub 2} NPs-HSA complex were discussed.

  11. Analysis of binding properties and interaction of thiabendazole and its metabolite with human serum albumin via multiple spectroscopic methods.

    Science.gov (United States)

    Sun, Qiaomei; He, Jiawei; Yang, Hongqin; Li, Shanshan; Zhao, Ludan; Li, Hui

    2017-10-15

    Thiabendazole (TBZ), which is oxidized into 5-hydroxythiabendazole (5-OH-TBZ) in vivo, is a commonly used food preservative. Interactions of TBZ and 5-OH-TBZ with human serum albumin (HSA) were comprehensively studied via multiple spectroscopic methods and molecular docking. This study focussed on the mechanistic and structural information on binding of TBZ and 5-OH-TBZ to HSA to evaluate the impact of the food additive on HSA. 1 H NMR spectra of the two ligands showed the binding exists. ITC and fluorescence spectroscopy results revealed that TBZ was a stronger ligand, with a binding constant of 10 5 l/mol and formed a more stable complex with HSA than did 5-OH-TBZ via electrostatic interaction. Spectroscopic results (UV-vis, FT-IR, and CD) showed that TBZ and 5-OH-TBZ caused conformational changes in HSA, in which α-helix and β-turn transformed into β-sheet, causing HSA structure to loosen. Docking programs showed that both TBZ and 5-OH-TBZ bound to HSA via IB. Copyright © 2017 Elsevier Ltd. All rights reserved.

  12. Binding of antioxidant flavonol morin to the native state of bovine serum albumin: Effects of urea and metal ions on the binding

    Energy Technology Data Exchange (ETDEWEB)

    Singha Roy, Atanu; Dinda, Amit Kumar; Chaudhury, Susmitnarayan; Dasgupta, Swagata, E-mail: swagata@chem.iitkgp.ernet.in

    2014-01-15

    In consideration of the various medicinal aspects of the flavonoid polyphenols, the interaction of morin with bovine serum albumin (BSA) has been investigated using multi-spectroscopic approaches. The pKa{sub 1} of morin being 5.09, which is below physiological pH, binding studies provide important insights into its potential use as a biotherapeutic. The binding was performed under different pH (5, 7 and 9) conditions and in absence and presence of Cu(II) and Fe(III) ions. It is observed that the presence of metal ions affect the binding of morin towards BSA. The binding with BSA results in a motional restriction of morin in solution that causes an increase in anisotropy (r), rotational correlation time (t{sub r}) and steady-state lifetime (t{sub av}) of the ligand. Urea causes denaturation of BSA resulting in the release of morin from the protein core as determined from both the steady-state fluorescence and anisotropy (r) measurements. The possibility of non-radiative energy transfer from the donor tryptophan to the acceptor morin is detected following the Förster's theory. The site marker displacement studies along with the molecular docking results indicated that morin binds to the hydrophobic pocket of site 1 (subdomain IIA) near Trp 213 of BSA. -- Highlights: • Binding mainly occurs through the electrostatic forces with partial hydrophobic association. • Negative ΔG° indicates the spontaneity of the complexation between morin and BSA. • Morin binds near Trp 213 (site 1, subdomain IIA) of BSA only in its native state. • Lifetime of morin increases as a function of BSA. • Motional restriction of morin occurs in the presence of BSA.

  13. Molecular interaction study of flavonoid derivative 3d with human serum albumin using multispectroscopic and molecular modeling approach.

    Science.gov (United States)

    Wei, Juntong; Jin, Feng; Wu, Qin; Jiang, Yuyang; Gao, Dan; Liu, Hongxia

    2014-08-01

    Human serum albumin (HSA) has been developed as a model protein to study drug-protein interaction. In the present work, the interaction between our synthesized flavonoid derivative 3d (possessing potent antitumor activity against HepG2 cells) and HSA was investigated using fluorescence spectroscopy, circular dichroism spectroscopy, UV-vis spectroscopy and molecular modeling approach. Fluorescence spectroscopy showed that the fluorescence of HSA can be quenched remarkably by 3d under physiological condition with a slight shift of maximum fluorescence emission bands from 360nm to 363nm. Calculated results from Stern-Volmer equation and modified Stern-Volmer equation indicated that the fluorescence was quenched by static quenching processing with association constant 5.26±0.04×10(4)L mol(-1) at 298K. After comprehensive consideration of the free energy change ΔG, enthalpy change ΔH and entropy change ΔS, electrostatic interactions were confirmed as the main factor that participate in stabilizing the 3d-HSA complex. Both dichroism spectroscopy and UV-vis spectroscopy indicated conformational change of HSA after binding to 3d. Moreover, the structure of HSA was loosened and the percentage of α-helix decreased with increasing concentration of 3d. Molecular modeling results demonstrated that 3d could bind to HSA well into subdomain IIA, which is related to its capability of deposition and delivery. Three cation-π interactions and three hydrogen bonds occurred between 3d and amino acid residuals ARG218, ARG222 and LYS199. In conclusion, flavonoid derivative 3d can bind to HSA with noncovalent bond in a relatively stable way, so it can be delivered by HSA in a circulatory system. Copyright © 2014 Elsevier B.V. All rights reserved.

  14. Characterizing the binding interaction between antimalarial artemether (AMT) and bovine serum albumin (BSA): Spectroscopic and molecular docking methods.

    Science.gov (United States)

    Shi, Jie-Hua; Pan, Dong-Qi; Wang, Xiou-Xiou; Liu, Ting-Ting; Jiang, Min; Wang, Qi

    2016-09-01

    Artemether (AMT), a peroxide sesquiterpenoides, has been widely used as an antimalarial for the treatment of multiple drug-resistant strains of plasmodium falciparum malaria. In this work, the binding interaction of AMT with bovine serum albumin (BSA) under the imitated physiological conditions (pH7.4) was investigated by UV spectroscopy, fluorescence emission spectroscopy, synchronous fluorescence spectroscopy, Fourier transform infrared spectroscopy (FT-IR), circular dichroism (CD), three-dimensional fluorescence spectroscopy and molecular docking methods. The experimental results indicated that there was a change in UV absorption of BSA along with a slight red shift of absorption wavelength, indicating that the interaction of AMT with BSA occurred. The intrinsic fluorescence of BSA was quenched by AMT due to the formation of AMT-BSA complex. The number of binding sites (n) and binding constant of AMT-BSA complex were about 1 and 2.63×10(3)M(-1) at 298K, respectively, suggesting that there was stronger binding interaction of AMT with BSA. Based on the analysis of the signs and magnitudes of the free energy change (ΔG(0)), enthalpic change (ΔH(0)) and entropic change (ΔS(0)) in the binding process, it can be concluded that the binding of AMT with BSA was enthalpy-driven process due to |ΔH°|>|TΔS°|. The results of experiment and molecular docking confirmed the main interaction forces between AMT and BSA were van der Waals force. And, there was a slight change in the BSA conformation after binding AMT but BSA still retains its secondary structure α-helicity. However, it had been confirmed that AMT binds on the interface between sub-domain IIA and IIB of BSA. Copyright © 2016 Elsevier B.V. All rights reserved.

  15. Interaction of anticancer drug clofarabine with human serum albumin and human α-1 acid glycoprotein. Spectroscopic and molecular docking approach.

    Science.gov (United States)

    Ajmal, Mohammad Rehan; Nusrat, Saima; Alam, Parvez; Zaidi, Nida; Khan, Mohsin Vahid; Zaman, Masihuz; Shahein, Yasser E; Mahmoud, Mohamed H; Badr, Gamal; Khan, Rizwan Hasan

    2017-02-20

    The binding interaction between clofarabine, an important anticancer drug and two important carrier proteins found abundantly in human plasma, Human Serum Albumin (HSA) and α-1 acid glycoprotein (AAG) was investigated by spectroscopic and molecular modeling methods. The results obtained from fluorescence quenching experiments demonstrated that the fluorescence intensity of HSA and AAG is quenched by clofarabine and the static mode of fluorescence quenching is operative. UV-vis spectroscopy deciphered the formation of ground state complex between anticancer drug and the two studied proteins. Clofarabine was found to bind at 298K with both AAG and HSA with the binding constant of 8.128×10 3 and 4.120×10 3 for AAG and HSA, respectively. There is stronger interaction of clofarabine with AAG as compared to HSA. The Gibbs free energy change was found to be negative for the interaction of clofarabine with AAG and HSA indicating that the binding process is spontaneous. Binding of clofarabine with HSA and AAG induced ordered structures in both proteins and lead to molecular compaction. Clofarabine binds to HSA near to drug site II. Hydrogen bonding and hydrophobic interactions were the main bonding forces between HSA-clofarabine and AAG-clofarabine as revealed by docking results. This study suggests the importance of binding of anticancer drug to AAG spatially in the diseases like cancers where the plasma concentration of AAG increases many folds. Design of drug dosage can be adjusted accordingly to achieve optimal treatment outcome. Copyright © 2016 Elsevier B.V. All rights reserved.

  16. Cordycepin and N6-(2-hydroxyethyl-adenosine from Cordyceps pruinosa and their interaction with human serum albumin.

    Directory of Open Access Journals (Sweden)

    Zebin Meng

    Full Text Available Cordyceps pruinosa (CP is often used as Traditional Chinese Medicine, but the substance basis of its medicinal properties is unclear. In this study, two compounds were isolated from CP cultures by column chromatography, and identified as cordycepin and N6-(2-hydroxyethyl-adenosine (HEA by Nuclear Magnetic Resonance. In order to understand the efficacy of these two substances as potential therapeutic agents, it is necessary to explore their binding with proteins. The molecular mechanisms of interaction between cordycepin, HEA and human serum albumin (HSA were studied using UV and fluorescence spectroscopy. The bingding constants between HSA and cordycepin were 4.227, 3.573 and 3.076 × 10(3·at 17, 27 and 37°C respectively, and that of HSA and HEA were 27.102, 19.409 and 13.002 × 10(3·at the three tempretures respectively. Both cordycepin and HEA can quench the intrinsic fluorescence of HSA via static quenching, and they can bind with HSA to form complexes with a single binding site. The interaction forces between cordycepin and HSA were determined as electrostatic and hydrophobic, and those of HEA and HSA were hydrogen bonding and van der Waals forces. Using Foster's equation, the distance between fluorophores of cordycepin and HSA, and HEA and HSA are estimated to be 5.31 nm and 4.98 nm, respectively. In this study, cordycepin was isolated for the first time from CP, and will provide a new source of cordycepin and expand the use of this taxon. The interaction mechanisms between cordycepin and HSA was studied for the first time, which will provide a useful guide for the clinical application of cordycepin. The pharmacological importance of this study is to understand the interaction of HSA with cordycepin and HEA, which will be essential for the future designing of drugs based on the two compounds.

  17. Exploring the interaction between Salvia miltiorrhiza and human serum albumin: Insights from herb-drug interaction reports, computational analysis and experimental studies.

    Science.gov (United States)

    Shao, Xin; Ai, Ni; Xu, Donghang; Fan, Xiaohui

    2016-05-15

    Human serum albumin (HSA) binding is one of important pharmacokinetic properties of drug, which is closely related to in vivo distribution and may ultimately influence its clinical efficacy. Compared to conventional drug, limited information on this transportation process is available for medicinal herbs, which significantly hampers our understanding on their pharmacological effects, particularly when herbs and drug are co-administrated as polytherapy to the ailment. Several lines of evidence suggest the existence of Salvia miltiorrhiza-Warfarin interaction. Since Warfarin is highly HSA bound in the plasma with selectivity to site I, it is critical to evaluate the possibility of HSA-related herb-drug interaction. Herein an integrated approach was employed to analyze the binding of chemicals identified in S. miltiorrhiza to HSA. Molecular docking simulations revealed filtering criteria for HSA site I compounds that include docking score and key molecular determinants for binding. For eight representative ingredients from the herb, their affinity and specificity to HSA site I was measured and confirmed fluorometrically, which helps to improve the knowledge of interaction mechanisms between this herb and HSA. Our results indicated that several compounds in S. miltiorrhiza were capable of decreasing the binding constant of Warfarin to HSA site I significantly, which may increase free drug concentration in vivo, contributing to the herb-drug interaction observed clinically. Furthermore, the significance of HSA mediated herb-drug interactions was further implied by manual mining on the published literatures on S. miltiorrhiza. Copyright © 2016 Elsevier B.V. All rights reserved.

  18. Comparative analysis of the interaction of capecitabine and gefitinib with human serum albumin using (19)F nuclear magnetic resonance-based approach.

    Science.gov (United States)

    Wu, Di; Yan, Jin; Sun, Pingchuan; Xu, Kailin; Li, Shanshan; Yang, Hongqi; Li, Hui

    2016-09-10

    Monitoring the interaction between drugs and proteins is critical to understanding drug transport and metabolism underlying pharmacodynamics. The binding capacities to human serum albumin of two anticancer drugs, capecitabine and gefitinib, were compared via an approach combining (19)F NMR, (1)H saturation transfer difference (STD) NMR, circular dichroism and docking simulations. Results showed that the two drugs interaction with human serum albumin caused (19)F NMR signal shifted to different directions. Capecitabine had accurate binding site and higher binding affinity than gefitinib. This study provided fresh insights into ligand-protein interaction and the strength of (19)F NMR approach in biomedical research was well illustrated in this case. Copyright © 2016 Elsevier B.V. All rights reserved.

  19. New insight into protein-nanomaterial interactions with UV-visible spectroscopy and chemometrics: human serum albumin and silver nanoparticles.

    Science.gov (United States)

    Wang, Yong; Ni, Yongnian

    2014-01-21

    In recent years, great efforts have focused on the exploration and fabrication of protein nanoconjugates due to potential applications in many fields including bioanalytical science, biosensors, biocatalysis, biofuel cells and bio-based nanodevices. An important aspect of our understanding of protein nanoconjugates is to quantitatively understand how proteins interact with nanomaterials. In this report, human serum albumin (HSA) and citrate-coated silver nanoparticles (AgNPs) are selected as a case study of protein-nanomaterial interactions. UV-visible spectroscopy together with multivariate curve resolution by alternating least squares (MCR-ALS) algorithm is first exploited for the detailed study of AgNPs-HSA interactions. Introduction of the chemometrics tool allows extracting the kinetic profiles, spectra and distribution diagrams of two major absorbing pure species (AgNPs and AgNPs-HSA conjugate). These resolved profiles are then analysed to give the thermodynamic, kinetic and structural information of HSA binding to AgNPs. Transmission electron microscopy, circular dichroism spectroscopy and Fourier transform infrared spectroscopy are used to further characterize the complex system. Moreover, a sensitive spectroscopic biosensor for HSA is fabricated with the MCR-ALS resolved concentration of absorbing pure species. It is found that the linear range for the HSA nanosensor was from 1.9 nM to 45.0 nM with a detection limit of 0.9 nM. It is believed that the proposed method will play an important role in the fabrication and optimization of a robust nanobiosensor or cross-reactive sensors array for the detection and identification of biocomponents.

  20. Effect of pH on the interaction of vitamin B12 with bovine serum albumin by spectroscopic approaches

    Science.gov (United States)

    Li, Daojin; Zhang, Tian; Xu, Chen; Ji, Baoming

    2011-12-01

    The interaction mechanism between vitamin B12 (B12, cyanocobalamin) and bovine serum albumin (BSA) has been investigated by fluorescence, synchronous fluorescence, ultraviolet-vis (UV) absorbance, and three-dimensional fluorescence. The intrinsic fluorescence of BSA was strongly quenched by the addition of B12 in different pH buffer solutions (pH 2.5, 3.5, 5.0, 7.4, and 9.0) and spectroscopic observations are mainly rationalized in terms of a static quenching process at lower concentration of B12 ( CB12/ CBSA B12 ( CB12/ CBSA > 5). The structural characteristics of B12 and BSA were probed, and their binding affinities were determined under different pH conditions. The results indicated that the binding abilities of B12 to BSA in the acidic and basic pH regions (pH 2.5, 3.5, 5.0, and 9.0) were lower than that at simulating physiological condition (pH 7.4). In addition, the efficiency of energy transfer from tryptophan fluorescence to B12 was found to depend on the binding distance r between the donor and acceptor calculated using Förster's theory. The effect of B12 on the conformation of BSA was analyzed using UV, synchronous fluorescence and three-dimensional fluorescence under different pH conditions. These results showed that the binding of B12 to BSA causes apparent change in the secondary and tertiary structures of BSA.

  1. Voltammetric behavior of Mammeisin (MA) at a glassy carbon electrode and its interaction with Bovine Serum Albumin (BSA).

    Science.gov (United States)

    Leuna, Jules-Blaise Mabou; Sop, Sergeot Kungo; Makota, Suzanne; Njanja, Evangeline; Ebelle, Thiery Christophe; Azebaze, Anatole Guy; Ngameni, Emmanuel; Nassi, Achille

    2018-02-01

    The electrochemical oxidation of Mammeisin (MA) was studied in a solution containing acetone and 0.1M phosphate buffer +0.1M KCl (pH=5.3) at a glassy carbon electrode (GCE), using cyclic (CV) and square wave voltammetry (SWV). MA showed a quasi-reversible process, which is pH dependent and that involves the exchange of two electrons and two protons. The oxidation product was adsorbed by the electrode surface to form a film that blocks active sites over repetitive cyclic. Moreover, the interaction of MA and bovine serum albumin (BSA) was studied by CV and SWV at different pHs (5.4, 7.2, 9.5). As a result of the affinity binding with BSA, electrochemically inactive complex was formed. In addition, the oxidation potential of MA in the presence of BSA depends on the pH. The diffusion coefficients of both free and bound MA were estimated from the cyclic voltammetry data using the method developed by Randles-Sevich (D f =9.85×10 -5 cm 2 s -1 and D b =1.27×10 -9 cm 2 s -1 ) and the binding constant of MA-BSA complex, K=3.47×10 2 Lmol -1 , was obtained. Copyright © 2017. Published by Elsevier B.V.

  2. Spectroscopic and molecular docking studies on the interaction of human serum albumin with copper(II) complexes

    Science.gov (United States)

    Guhathakurta, Bhargab; Pradhan, Ankur Bikash; Das, Suman; Bandyopadhyay, Nirmalya; Lu, Liping; Zhu, Miaoli; Naskar, Jnan Prakash

    2017-02-01

    Two osazone based ligands, butane-2,3-dione bis(2‧-pyridylhydrazone) (BDBPH) and hexane-3,4-dione bis(2‧-pyridylhydrazone) (HDBPH), were synthesized out of the 2:1 M Schiff base condensation of 2-hydrazino pyridine respectively with 2,3-butanedione and 3,4-hexanedione. The X-ray crystal structures of both the ligands have been determined. The copper(II) complex of HDBPH has also been synthesized and structurally characterized. HDBPH and its copper(II) complex have thoroughly been characterized through various spectroscopic and analytical techniques. The X-ray crystal structure of the copper complex of HDBPH shows that it is a monomeric Cu(II) complex having 'N4O2' co-ordination chromophore. Interaction of human serum albumin (HSA) with these ligands and their monomeric copper(II) complexes have been studied by various spectroscopic means. The experimental findings show that the ligands as well as their copper complexes are good HSA binders. Molecular docking investigations have also been done to unravel the mode of binding of the species with HSA.

  3. Probing the interaction of a therapeutic flavonoid, pinostrobin with human serum albumin: multiple spectroscopic and molecular modeling investigations.

    Directory of Open Access Journals (Sweden)

    Shevin R Feroz

    Full Text Available Interaction of a pharmacologically important flavonoid, pinostrobin (PS with the major transport protein of human blood circulation, human serum albumin (HSA has been examined using a multitude of spectroscopic techniques and molecular docking studies. Analysis of the fluorescence quenching data showed a moderate binding affinity (1.03 × 10(5 M(-1 at 25°C between PS and HSA with a 1∶1 stoichiometry. Thermodynamic analysis of the binding data (ΔS = +44.06 J mol(-1 K(-1 and ΔH = -15.48 kJ mol(-1 and molecular simulation results suggested the involvement of hydrophobic and van der Waals forces, as well as hydrogen bonding in the complex formation. Both secondary and tertiary structural perturbations in HSA were observed upon PS binding, as revealed by intrinsic, synchronous, and three-dimensional fluorescence results. Far-UV circular dichroism data revealed increased thermal stability of the protein upon complexation with PS. Competitive drug displacement results suggested the binding site of PS on HSA as Sudlow's site I, located at subdomain IIA, and was well supported by the molecular modelling data.

  4. The influence of the flavonoid quercetin on the interaction of propranolol with human serum albumin: Experimental and theoretical approaches

    Energy Technology Data Exchange (ETDEWEB)

    Mohseni-Shahri, Fatemeh S., E-mail: fmohsenishahri@gmail.com [Department of Chemistry, Faculty of Science, Ferdowsi University of Mashhad, Mashhad (Iran, Islamic Republic of); Housaindokht, Mohammad R. [Department of Chemistry, Faculty of Science, Ferdowsi University of Mashhad, Mashhad (Iran, Islamic Republic of); Bozorgmehr, Mohammad R. [Department of Chemistry, Mashhad Branch, Islamic Azad University, Mashhad (Iran, Islamic Republic of); Moosavi-Movahedi, Ali A. [Institute of Biochemistry and Biophysics, University of Tehran, Tehran (Iran, Islamic Republic of)

    2014-10-15

    The binding of propranolol (PROP) to human serum albumin (HSA) in the absence and presence of quercetin (QUER) in aqueous solution was investigated by multiple techniques. The presence of quercetin (QUER) increased binding constant of propranolol (PROP) with HSA. Fluorescence spectroscopy showed that quercetin (QUER) could quench the HSA fluorescence spectra. The results of synchronous fluorescence, resonance light scattering (RLS) and three-dimensional fluorescence spectra showed that propranolol (PROP) and quercetin (QUER) would alter the micro-environment around tryptophan (Trp) and tyrosine (Tyr) residues. According molecular dynamics (MD) simulation results suggested that these ligands can interact with the protein, with affecting the secondary structure of HSA and with a modification of its tertiary structure. Molecular docking studies showed that the affinity and binding site of each of the ligands to HSA altered in the presence of the other. All above results may have related consequence in rationalizing the interferences of ordinary food to cardiac dysrhythmias treatments. - Highlights: • The presence of quercetin increased binding constant of propranolol with HSA. • Quercetin quenched the fluorescence of HSA through a static quenching mechanism. • The binding of propranolol and quercetin with HSA induced partial unfolding. • The tertiary structure of HSA changed after ligand binding. • After the binding of quercetin, the helix content of HSA declined.

  5. Spectroscopic analysis on structure-affinity relationship in the interactions of different oleanane-type triterpenoids with bovine serum albumin.

    Science.gov (United States)

    Hou, Jia; Wang, Zhenzhong; Yue, Ying; Li, Qian; Shao, Shijun

    2015-09-01

    Oleanane-type triterpenoids serve as an important group of plant secondary metabolites with a variety of biological activities and the C-3 position substitution pattern is a significant structural feature for their biological activities. Three selected oleanane-type triterpenoids (glycyrrhizin, glycyrrhetinic acid, and carbenoxolone) bearing different substituents (glucuronic acid dimer, hydroxyl, and succinyl groups) at the C-3 position were studied for their affinities to bind bovine serum albumin (BSA) by steady-state fluorescence, synchronous, three-dimensional fluorescence and ultraviolet-visible (UV-vis) absorption spectra. The binding mechanism of the triterpenoids to BSA is due to the formation of the triterpenoids-BSA complex and the binding affinity is strongest for carbenoxolone and ranked in the order carbenoxolone > glycyrrhetinic acid > glycyrrhizin. The thermodynamic parameters calculated at different temperatures showed that triterpenoids binding to BSA primarily depended on hydrophobic interaction and hydrogen bonding. The distance between the bound triterpenoid and BSA was determined on the basis of the Förster's energy transfer theory. Displacement experiments using phenylbutazone and ibuprofen showed the binding site of triterpenoids on BSA at subdomain IIA (Sudlow's site I). The effect of triterpenoids on BSA conformation was analyzed by UV-vis absorption, and synchronous and three-dimensional fluorescence spectra. These results revealed that the C-3 position substitution pattern significantly affects the structure-affinity relationships of oleanane-type triterpenoid binding to BSA and further affects the bioavailability of triterpenoids in the blood circulatory system. Copyright © 2014 John Wiley & Sons, Ltd.

  6. Fluorescent copper(II complexes: The electron transfer mechanism, interaction with bovine serum albumin (BSA and antibacterial activity

    Directory of Open Access Journals (Sweden)

    Madhumita Hazra

    2017-01-01

    Full Text Available Dinuclear copper(II complexes with formula [Cu2(L2(N32] (1 and [Cu2(L2(NCS2] (2 HL = (1-[(3-methyl-pyridine-2-ylimino-methyl]-naphthalen-2-ol were synthesized by controlling the molar ratio of Cu(OAC2·6H2O, HL, sodium azide (1 and ammonium thiocyanate (2. The end on bridges appear exclusively in azide and thiocyanate to copper complexes. The electron transfer mechanism of copper(II complexes is examined by cyclic voltammetry indicating copper(II complexes are Cu(II/Cu(I couple. The interactions of copper(II complexes towards bovine serum albumin (BSA were examined with the help of absorption and fluorescence spectroscopic tools. We report a superficial solution-based route for the synthesis of micro crystals of copper complexes with BSA. The antibacterial activity of the Schiff base and its copper complexes were investigated by the agar disc diffusion method against some species of pathogenic bacteria (Escherichia coli, Vibrio cholerae, Streptococcus pneumonia and Bacillus cereus. It has been observed that the antibacterial activity of all complexes is higher than the ligand.

  7. Synthesis and characterization of a lipidic alpha amino acid: solubility and interaction with serum albumin and lipid bilayers.

    Science.gov (United States)

    Filipe, Hugo A L; Coreta-Gomes, Filipe M; Velazquez-Campoy, Adrian; Almeida, Ana R; Peixoto, Andreia F; Pereira, Mariette M; Vaz, Winchil L C; Moreno, Maria J

    2013-04-04

    The lipidic α-amino acid with 11 carbons in the alkyl lateral chain (α-aminotridecanoic acid) was synthesized via multicomponent hydroformylation/Strecker reaction, which is a greener synthetic approach to promote this transformation relative to previously described methods. Its solubility and aggregation behavior in aqueous solutions was characterized, as well as the interaction with lipid bilayers. Lipidic amino acids are very promising molecules in the development of prodrugs with increased bioavailability due to the presence of the two polar functional groups and nonpolar alkyl chain. They are also biocompatible surfactants that may be used in the food and pharmaceutical industry. In this work we have conjugated the lipidic amino acid with a fluorescent polar group (7-nitrobenz-2-oxa-1,3-diazol-4-yl), to mimic drug conjugates, and its association with serum proteins and lipid bilayers was characterized. The results obtained indicate that conjugates of polar molecules with lipidic α-amino acid, via covalent attachment to the amine group, have a relatively high solubility in aqueous solutions due to their negative global charge. They bind to serum albumin with intermediate affinity and show a very high partition coefficient into lipid bilayers in the liquid-disordered state. The attachment of the polar group to the lipidic amino acid increased strongly the aqueous solubility of the amphiphile, although the partition coefficient into lipid membranes was not significantly reduced. Conjugation of polar drugs with lipidic amino acids is therefore an efficient approach to increase their affinity for biomembranes.

  8. Theoretical model to investigate the alkyl chain and anion dependent interactions of gemini surfactant with bovine serum albumin.

    Science.gov (United States)

    Vishvakarma, Vijay K; Kumari, Kamlesh; Patel, Rajan; Dixit, V S; Singh, Prashant; Mehrotra, Gopal K; Chandra, Ramesh; Chakrawarty, Anand Kumar

    2015-05-15

    Surfactants are used to prevent the irreversible aggregation of partially refolded proteins and they also assist in protein refolding. We have reported the design and screening of gemini surfactant to stabilize bovine serum albumin (BSA) with the help of computational tool (iGEMDOCK). A series of gemini surfactant has been designed based on bis-N-alkyl nicotinate dianion via varying the alkyl group and anion. On changing the alkyl group and anion of the surfactant, the value of Log P changes means polarity of surfactant can be tuned. Further, the virtual screening of the gemini surfactant has been carried out based on generic evolutionary method. Herein, thermodynamic data was studied to determine the potential of gemini surfactant as BSA stabilizer. Computational tools help to find out the efficient gemini surfactant to stabilize the BSA rather than to use the surfactant randomly and directionless for the stabilization. It can be confirmed through the experimental techniques. Previously, researcher synthesized one of the designed and used gemini surfactant to stabilize the BSA and their interactions were confirmed through various techniques and computational docking. But herein, the authors find the most competent gemini surfactant to stabilize BSA using computational tools on the basis of energy score. Different from the single chain surfactant, the gemini surfactants exhibit much stronger electrostatic and hydrophobic interactions with the protein and are thus effective at much lower concentrations. Based on the present study, it is expected that gemini surfactants may prove useful in the protein stabilization operations and may thus be effectively employed to circumvent the problem of misfolding and aggregation. Copyright © 2015 Elsevier B.V. All rights reserved.

  9. Interactions between {beta}-carboline alkaloids and bovine serum albumin: Investigation by spectroscopic approach

    Energy Technology Data Exchange (ETDEWEB)

    Nafisi, Shohreh, E-mail: drshnafisi@gmail.com [Department of Chemistry, Islamic Azad University, Central Tehran Branch (IAUCTB), Tehran (Iran, Islamic Republic of); Panahyab, Ataollah [Department of Chemistry, Islamic Azad University, Central Tehran Branch (IAUCTB), Tehran (Iran, Islamic Republic of); Bagheri Sadeghi, Golshan [Department of Biology, Islamic Azad University, Science and Research Branch, Tehran (Iran, Islamic Republic of)

    2012-09-15

    {beta}-Carboline alkaloids are present in medicinal plants such as Peganum harmala L. that have been used as folk medicine in anticancer therapy. BSA is the major soluble protein constituent of the circulatory system, and has many physiological functions including the transport of a variety of compounds. This study is the first attempt to investigate the binding of {beta}-carboline alkaloids to BSA by using a constant protein concentration and varying drug concentrations at pH 7.2. FTIR and UV-Vis spectroscopic methods were used to analyze the binding modes of {beta}-carboline alkaloids, the binding constants and the effects of drug complexation on BSA stability and conformation. Spectroscopic evidence showed that {beta}-carboline alkaloids bind BSA via hydrophobic interaction and van der Waals contacts along with H-bonding with the -NH groups, with overall binding constants of K{sub harmine-BSA}=2.04 Multiplication-Sign 10{sup 4} M{sup -1}, K{sub tryptoline-BSA}=1.2 Multiplication-Sign 10{sup 4} M{sup -1}, K{sub harmaline-BSA}=5.04 Multiplication-Sign 10{sup 3} M{sup -1}, K{sub harmane-BSA}=1.41 Multiplication-Sign 10{sup 3} M{sup -1} and K{sub harmalol-BSA}=1.01 Multiplication-Sign 10{sup 3} M{sup -1}, assuming that there is one drug molecule per protein. The BSA secondary structure was altered with a major decrease of {alpha}-helix from 64% (free protein) to 59% (BSA-harmane), 56% (BSA-harmaline and BSA-harmine), 55% (BSA-tryptoline), 54% (BSA-harmalol) and {beta}-sheet from 15% (free protein) to 6-8% upon {beta}-carboline alkaloids complexation, inducing a partial protein destabilization. - Highlights: Black-Right-Pointing-Pointer We model the binding of {beta}-carboline alkaloids to BSA by using the spectroscopic methods. Black-Right-Pointing-Pointer We investigate the effects of drug complexation on BSA stability and conformation. Black-Right-Pointing-Pointer A partial protein destabilization occurred at high alkaloids concentration. Black

  10. Interaction of NAEn-s-n gemini surfactants with bovine serum albumin: A structure-activity probe

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Houchen [Chemical Synthesis and Pollution Control Key Laboratory of Sichuan Province, China West Normal University, Nanchong, Sichuan 637009 (China); Jiang, Xiaohui, E-mail: jxh2314508@163.com [Chemical Synthesis and Pollution Control Key Laboratory of Sichuan Province, China West Normal University, Nanchong, Sichuan 637009 (China); Zhou, Limei; Cheng, Zhenjun; Yin, Wenmin [Chemical Synthesis and Pollution Control Key Laboratory of Sichuan Province, China West Normal University, Nanchong, Sichuan 637009 (China); Duan, Ming; Liu, Pingli [State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Southwest Petroleum University, Chengdu, Sichuan 610500 (China); Jiang, Xiaomin [Southwest Electric Power Design Institute, Chengdu, Sichuan 61002 (China)

    2013-02-15

    Gemini surfactants, {alpha},{omega}-bis (3-(alkyloxylacyl) pyridinium) propane/butane/hexane dibromide (designated as NAEn-s-n), have been prepared and the interactions of NAEn-s-n with bovine serum albumin (BSA) were investigated by fluorescence, UV-vis and FTIR spectroscopies. The intrinsic fluorescence of BSA was significantly quenched by NAEn-s-n through static quenching. NAEn-s-n combined mainly with Trp-212 in BSA by van der Waals force, hydrogen bonding, electrostatic and hydrophobic interaction. The binding process was spontaneous, exothermic and enthalpy driven. The synchronous and tridimensional fluorescence revealed the changed conformation of the peptide backbone and the altered microenvironment of tryptophan and tyrosine residues in BSA. The red-shift in the IR spectrum of the BSA amide I peak, the blue-shift of amide II peak, as well as the appearance of a new peak at around 1514 cm{sup -1} suggested unfolding of the protein secondary structure upon the addition of NAEn-s-n. The lengths of spacer and hydrophobic chain greatly influenced the interaction. With the lengthening alkyl chain in NAEn-s-n, the binding constant of BSA-NAEn-4-n increased, while the thermodynamic parameters and the {alpha}-helix content of BSA decreased. This indicated an enhancement of hydrophobic interaction between BSA and NAEn-s-n. However, these values (i.d. binding constant, {alpha}-helix content etc.) fluctuated with methylene numbers in the spacer of NAEn-s-n, which might be due to the different spatial arrangement of the spacer of the gemini surfactants. This investigation may shed new light on the understanding of structure-activity correlation. Highlights: Black-Right-Pointing-Pointer NAEn-s-n is a serial of newly synthesized cationic gemini surfactants. Black-Right-Pointing-Pointer NAEn-s-n binds in hydrophobic domain II and III of BSA by hydrophobic forces. Black-Right-Pointing-Pointer The concentrations of NAEn-s-n and BSA affect the binding constants and the

  11. Domain-specific interactions between MLN8237 and human serum albumin estimated by STD and WaterLOGSY NMR, ITC, spectroscopic, and docking techniques

    OpenAIRE

    Yang, Hongqin; Liu, Jiuyang; Huang, Yanmei; Gao, Rui; Tang, Bin; Li, Shanshan; He, Jiawei; Li, Hui

    2017-01-01

    Alisertib (MLN8237) is an orally administered inhibitor of Aurora A kinase. This small-molecule inhibitor is under clinical or pre-clinical phase for the treatment of advanced malignancies. The present study provides a detailed characterization of the interaction of MLN8237 with a drug transport protein called human serum albumin (HSA). STD and WaterLOGSY nuclear magnetic resonance (NMR)-binding studies were conducted first to confirm the binding of MLN8237 to HSA. In the ligand orientation a...

  12. Influence of mixed electrolytes and pH on adsorption of bovine serum albumin in hydrophobic interaction chromatography.

    Science.gov (United States)

    Hackemann, Eva; Hasse, Hans

    2017-10-27

    Using salt mixtures instead of single salts can be beneficial for hydrophobic interaction chromatography (HIC). The effect of electrolytes on the adsorption of proteins, however, depends on the pH. Little is known on that dependence for mixed electrolytes. Therefore, the effect of the pH on protein adsorption from aqueous solutions containing mixed salts is systematically studied in the present work for a model system: the adsorption of bovine serum albumin (BSA) on the mildly hydrophobic resin Toyopearl PPG-600M. The pH is adjusted to 4.0, 4.7 or 7.0 using 25mM sodium phosphate or sodium citrate buffer. Binary and ternary salt mixtures of sodium chloride, ammonium chloride, sodium sulfate and ammonium sulfate as well as the pure salts are used at overall ionic strengths between 1500 and 4200mM. The temperature is always 25°C. The influence of the mixed electrolytes on the adsorption behavior of BSA changes completely with varying pH. Positive as well as negative cooperative effects of the mixed electrolytes are observed. The results are analyzed using a mathematical model which was recently introduced by our group. In that model the influence of the electrolytes is described by a Taylor series expansion in the individual ion molarities. After suitable parametrization using a subset of the data determined in the present work, the model successfully predicts the influence of mixed electrolytes on the protein adsorption. Furthermore, results for BSA from the present study are compared to literature data for lysozyme, which are available for the same adsorbent, temperature and salts. By calculating the ratio of the loading of the adsorbent for both proteins particularly favorable separation conditions can be selected. Hence, a model-based optimization of solvents for protein separation is possible. Copyright © 2017 Elsevier B.V. All rights reserved.

  13. Interactions of perfluorooctanoic acid and perfluorooctanesulfonic acid with serum albumins by native mass spectrometry, fluorescence and molecular docking.

    Science.gov (United States)

    Chi, Quan; Li, Zhixiong; Huang, Juan; Ma, Jieyao; Wang, Xian

    2018-05-01

    The binding information of perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS) with bovine and human serum albumins was investigated and characterized in details by using a combination method of electrospray ionization mass spectrometry (ESI-MS), fluorescence, circular dichroism (CD) and molecular docking (MD). The ESI-MS analysis revealed that maximally eight PFOA or PFOS molecules could bind to serum albumins at high mole ratios of PFOA/PFOS. Association constants were measured by ESI-MS and suggested that PFOS had a better binding affinity than PFOA. PFOA and PFOS were likely to bind with serum albumins in more than one pocket. The CD data demonstrated that binding of PFOA and PFOS could change the conformation of serum albumins with decreasing α-helix content, which may affect the protein physiological function. The phenomenon of protein fluorescence quenching by the binding of PFOA and PFOS indicated that the hydrophobic pocket proximate to Trp 214 in human serum albumin might be one of the dominated binding sites. This assumption was further confirmed by MD simulation. Consistent to ESI-MS observation, MD results also displayed a stronger binding affinity of PFOS than PFOA according to the calculated binding free energy, which is probably ascribed to one more hydrogen bond formed in the PFOS-bound protein complexes. Copyright © 2018 Elsevier Ltd. All rights reserved.

  14. Different interactions of fungi with toxic metals

    OpenAIRE

    Fanelli, Corrado; Fabbri, Anna Adele; Pilo, Giuseppina; Luongo, Laura; Corazza, Luciana; Melis, Pietro

    1994-01-01

    Many papers have reported the uptake and translocation of toxic metals and radionuclides to fruit bodies of edible fungi and also to mycelia biomass. Our aim is to study how to reduce the metal phytotoxicity by mychorrizal fungi pointing at land reclamation and at the detoxification of metal/radionuclides-containing industrial effluents.

  15. NMR identification of endogenous metabolites interacting with fatted and non-fatted human serum albumin in blood plasma: Fatty acids influence the HSA-metabolite interaction

    Science.gov (United States)

    Jupin, Marc; Michiels, Paul J.; Girard, Frederic C.; Spraul, Manfred; Wijmenga, Sybren S.

    2013-03-01

    Metabolites and their concentrations are direct reporters on body biochemistry. Thanks to technical developments metabolic profiling of body fluids, such as blood plasma, by for instance NMR has in the past decade become increasingly accurate enabling successful clinical diagnostics. Human Serum Albumin (HSA) is the main plasma protein (∼60% of all plasma protein) and responsible for the transport of endogenous (e.g. fatty acids) and exogenous metabolites, which it achieves thanks to its multiple binding sites and its flexibility. HSA has been extensively studied with regard to its binding of drugs (exogenous metabolites), but only to a lesser extent with regard to its binding of endogenous (non-fatty acid) metabolites. To obtain correct NMR measured metabolic profiles of blood plasma and/or potentially extract information on HSA and fatty acids content, it is necessary to characterize these endogenous metabolite/plasma protein interactions. Here, we investigate these metabolite-HSA interactions in blood plasma and blood plasma mimics. The latter contain the roughly twenty metabolites routinely detected by NMR (also most abundant) in normal relative concentrations with fatted or non-fatted HSA added or not. First, we find that chemical shift changes are small and seen only for a few of the metabolites. In contrast, a significant number of the metabolites display reduced resonance integrals and reduced free concentrations in the presence of HSA or fatted HSA. For slow-exchange (or strong) interactions, NMR resonance integrals report the free metabolite concentration, while for fast exchange (weak binding) the chemical shift reports on the binding. Hence, these metabolites bind strongly to HSA and/or fatted HSA, but to a limited degree because for most metabolites their concentration is smaller than the HSA concentration. Most interestingly, fatty acids decrease the metabolite-HSA binding quite significantly for most of the interacting metabolites. We further find

  16. HPMA-based drug delivery system and its interactions of human serum albumin: SAXS, ITC, and NMR study

    Czech Academy of Sciences Publication Activity Database

    Filippov, Sergey K.; Kaberov, Leonid; Zhang, X.; Niebuur, B.-J.; Chytil, Petr; Etrych, Tomáš; Wieland, F.; Velychkivska, Nadiia; Starovoytova, Larisa; Svergun, D.; Papadakis, C.

    2017-01-01

    Roč. 254, 20 August (2017), s. 455 ISSN 0065-7727. [ACS National Meeting & Exposition /254./. 20.08.2017-24.08.2017, Washington] R&D Projects: GA ČR(CZ) GC15-10527J Institutional support: RVO:61389013 Keywords : HPMA * human serum albumin * SAXS Subject RIV: CF - Physical ; Theoretical Chemistry OBOR OECD: Physical chemistry

  17. A combined spectroscopic and molecular docking study on site selective binding interaction of Toluidine blue O with Human and Bovine serum albumins

    Energy Technology Data Exchange (ETDEWEB)

    Selva Sharma, Arumugam [Department of Chemistry, Bharathiar University, Coimbatore 641046 (India); Anandakumar, Shanmugam [Department of Bioinformatics, Bharathiar University, Coimbatore 641046 (India); Ilanchelian, Malaichamy, E-mail: chelian73@yahoo.com [Department of Chemistry, Bharathiar University, Coimbatore 641046 (India)

    2014-07-01

    In the present investigation the interaction of a biologically active photodynamic therapeutic agent Toluidine blue O (TBO) with Serum albumins viz Human serum albumin (HSA) and Bovine serum albumin (BSA) was studied using absorption, emission, circular dichroism spectroscopy and molecular docking experiments. The emission titration experiments between HSA/BSA and TBO revealed the existence of strong interactions between TBO and the proteins. The site competitive experiment of HSA and BSA showed that the primary binding site of TBO is located in site I of HSA/BSA involving hydrophobic, hydrogen bonding and electrostatic interaction. To ascertain the results of site competitive experiments, molecular docking was utilized to characterize the binding models of TBO–HSA/BSA complexes. From the molecular docking studies, free energy calculations were undertaken to examine the energy contributions and the role of various amino acid residues of HSA/BSA in TBO binding. The existence of Forster Resonance Energy Transfer (FRET) between the ligand and the protein was utilized to calculate the donor–acceptor distance of TBO and protein. The TBO induced conformational changes of HSA/BSA was established using synchronous emission, three dimensional emission and circular dichroism studies. - Highlights: • Site selective binding interaction of TBO with HSA and BSA were investigated. • TBO quenches the intrinsic fluorescence of HSA/BSA by static quenching process. • Computational studies of TBO with HSA/BSA substantiate the experimental findings. • 3D and CD spectral studies of TBO–HSA/BSA revealed structural changes in protein. • The distance (r) between TBO and HSA/BSA were estimated from FRET theory.

  18. Long-range interactions among three alkali-metal atoms

    International Nuclear Information System (INIS)

    Marinescu, M.; Starace, A.F.

    1996-01-01

    The long-range asymptotic form of the interaction potential surface for three neutral alkali-metal atoms in their ground states may be expressed as an expansion in inverse powers of inter-nuclear distances. The first leading powers are proportional to the dispersion coefficients for pairwise atomic interactions. They are followed by a term responsible for a three body dipole interaction. The authors results consist in evaluation of the three body dipole interaction coefficient between three alkali-metal atoms. The generalization to long-range n atom interaction terms will be discussed qualitatively

  19. Influence of core and maltose surface modification of PEIs on their interaction with plasma proteins-Human serum albumin and lysozyme.

    Science.gov (United States)

    Wrobel, Dominika; Marcinkowska, Monika; Janaszewska, Anna; Appelhans, Dietmar; Voit, Brigitte; Klajnert-Maculewicz, Barbara; Bryszewska, Maria; Štofik, Marcel; Herma, Regina; Duchnowicz, Piotr; Maly, Jan

    2017-04-01

    Regardless of the route of administration, some or all of a therapeutic agent will appear in the blood stream, where it can act on blood cells and other components of the plasma. Recently we have shown that poly(ethylene imines) (PEIs) which interact with plasma proteins are taken up into erythrocyte membranes. These observations led us to investigate the interactions between maltose functionalized hyperbranched PEIs (PEI-Mal) and plasma proteins. Two model proteins were chosen - human serum albumin (HSA) (albumins constitute ∼60% of all plasma proteins), and lysozyme. HSA is a negatively charged 66kDa protein at neutral pH, whereas lysozyme is a positively charged 14kDa protein. Fluorescence quenching and changes in the conformation of the amino acid tryptophan, diameter and zeta potential of proteins were investigated to evaluate the interaction of PEI-Mal with proteins. PEI-Mal interacts with both types of proteins. The strength of dendritic glycopolymer interactions was generally weak, especially with lysozyme. Greater changes were found with HSA, mainly triggered by hydrogen bonds and the electrostatic interaction properties of dendritic glycopolymers. Moreover, the structure and the size of PEI-Mal macromolecules affected these interactions; larger macromolecules with more sugar groups (95% maltose units) interacted more strongly with proteins than smaller ones with lower sugar modification (33% maltose units). Due to (i) the proven overall low toxicity of sugar-modified PEIs and, (ii) their ability to interact preferentially through hydrogen bonds with proteins of human plasma or possibly with other interesting protein targets, PEI-Mal is a good candidate for creating therapeutic nanoparticles in the fast developing field of nanomedicine. Copyright © 2017 Elsevier B.V. All rights reserved.

  20. Trace Metal Requirements and Interactions in Symbiodinium kawagutii

    Science.gov (United States)

    Rodriguez, Irene B.; Ho, Tung-Yuan

    2018-01-01

    Photosynthetic organisms need trace metals for various biological processes and different groups of microalgae have distinctive obligate necessities due to their respective biochemical requirements and ecological niches. We have previously shown that the dinoflagellate Symbiodinium kawagutii requires high concentrations of bioavailable Fe to achieve optimum growth. Here, we further explored the trace metal requirements of S. kawagutii with intensive focus on the effect of individual metal and its interaction with other divalent metals. We found that low Zn availability significantly decreases growth rates and results in elevated intracellular Mn, Co, Ni, and Fe quotas in the dinoflagellate. The results highlight the complex interaction among trace metals in S. kawagutii and suggest either metal replacement strategy to counter low Zn availability or enhanced uptake of other metals by non-specific divalent metal transporters. In this work, we also examined the Fe requirement of S. kawagutii using continuous cultures. We validated that 500 pM of Fe′ was sufficient to support maximum cell density during steady state growth period either at 26 or 28°C. This study shows that growth of S. kawagutii was limited by metal availability in the following order, Fe > Zn > Mn > Cu > Ni > Co. The fundamental information obtained for the free-living Symbiodinium shall provide insights into how trace metal availability, either from ambient seawater or hosts, affects growth and proliferation of symbiotic dinoflagellates and the interaction between symbiont and their hosts. PMID:29467748

  1. Trace Metal Requirements and Interactions inSymbiodinium kawagutii.

    Science.gov (United States)

    Rodriguez, Irene B; Ho, Tung-Yuan

    2018-01-01

    Photosynthetic organisms need trace metals for various biological processes and different groups of microalgae have distinctive obligate necessities due to their respective biochemical requirements and ecological niches. We have previously shown that the dinoflagellate Symbiodinium kawagutii requires high concentrations of bioavailable Fe to achieve optimum growth. Here, we further explored the trace metal requirements of S. kawagutii with intensive focus on the effect of individual metal and its interaction with other divalent metals. We found that low Zn availability significantly decreases growth rates and results in elevated intracellular Mn, Co, Ni, and Fe quotas in the dinoflagellate. The results highlight the complex interaction among trace metals in S. kawagutii and suggest either metal replacement strategy to counter low Zn availability or enhanced uptake of other metals by non-specific divalent metal transporters. In this work, we also examined the Fe requirement of S. kawagutii using continuous cultures. We validated that 500 pM of Fe' was sufficient to support maximum cell density during steady state growth period either at 26 or 28°C. This study shows that growth of S. kawagutii was limited by metal availability in the following order, Fe > Zn > Mn > Cu > Ni > Co. The fundamental information obtained for the free-living Symbiodinium shall provide insights into how trace metal availability, either from ambient seawater or hosts, affects growth and proliferation of symbiotic dinoflagellates and the interaction between symbiont and their hosts.

  2. Trace Metal Requirements and Interactions in Symbiodinium kawagutii

    Directory of Open Access Journals (Sweden)

    Irene B. Rodriguez

    2018-02-01

    Full Text Available Photosynthetic organisms need trace metals for various biological processes and different groups of microalgae have distinctive obligate necessities due to their respective biochemical requirements and ecological niches. We have previously shown that the dinoflagellate Symbiodinium kawagutii requires high concentrations of bioavailable Fe to achieve optimum growth. Here, we further explored the trace metal requirements of S. kawagutii with intensive focus on the effect of individual metal and its interaction with other divalent metals. We found that low Zn availability significantly decreases growth rates and results in elevated intracellular Mn, Co, Ni, and Fe quotas in the dinoflagellate. The results highlight the complex interaction among trace metals in S. kawagutii and suggest either metal replacement strategy to counter low Zn availability or enhanced uptake of other metals by non-specific divalent metal transporters. In this work, we also examined the Fe requirement of S. kawagutii using continuous cultures. We validated that 500 pM of Fe′ was sufficient to support maximum cell density during steady state growth period either at 26 or 28°C. This study shows that growth of S. kawagutii was limited by metal availability in the following order, Fe > Zn > Mn > Cu > Ni > Co. The fundamental information obtained for the free-living Symbiodinium shall provide insights into how trace metal availability, either from ambient seawater or hosts, affects growth and proliferation of symbiotic dinoflagellates and the interaction between symbiont and their hosts.

  3. Phenytoin-Bovine Serum Albumin interactions - modeling plasma protein - drug binding: A multi-spectroscopy and in silico-based correlation

    Science.gov (United States)

    Suresh, P. K.; Divya, Naik; Nidhi, Shah; Rajasekaran, R.

    2018-03-01

    The study focused on the analysis of the nature and site of binding of Phenytoin (PHT) -(a model hydrophobic drug) with Bovine Serum Albumin (BSA) (a model protein used as a surrogate for HSA). Interactions with defined amounts of Phenytoin and BSA demonstrated a blue shift (hypsochromic -change in the microenvironment of the tryptophan residue with decrease in the polar environment and more of hydrophobicity) with respect to the albumin protein and a red shift (bathochromic -hydrophobicity and polarity related changes) in the case of the model hydrophobic drug. This shift, albeit lower in magnitude, has been substantiated by a fairly convincing, Phenytoin-mediated quenching of the endogenous fluorophore in BSA. Spectral shifts studied at varying pH, temperatures and incubation periods (at varying concentrations of PHT with a defined/constant BSA concentration) showed no significant differences (data not shown). FTIR analysis provided evidence of the interaction of PHT with BSA with a stretching vibration of 1737.86 cm- 1, apart from the vibrations characteristically associated with the amine and carboxyl groups respectively. Our in vitro findings were extended to molecular docking of BSA with PHT (with the different ionized forms of the drug) and the subsequent LIGPLOT-based analysis. In general, a preponderance of hydrophobic interactions was observed. These hydrophobic interactions corroborate the tryptophan-based spectral shifts and the fluorescence quenching data. These results substantiates our hitherto unreported in vitro/in silico experimental flow and provides a basis for screening other hydrophobic drugs in its class.

  4. Understanding metallic bonding: Structure, process and interaction by Rasch analysis

    Science.gov (United States)

    Cheng, Maurice M. W.; Oon, Pey-Tee

    2016-08-01

    This paper reports the results of a survey of 3006 Year 10-12 students on their understandings of metallic bonding. The instrument was developed based on Chi's ontological categories of scientific concepts and students' understanding of metallic bonding as reported in the literature. The instrument has two parts. Part one probed into students' understanding of metallic bonding as (a) a submicro structure of metals, (b) a process in which individual metal atoms lose their outermost shell electrons to form a 'sea of electrons' and octet metal cations or (c) an all-directional electrostatic force between delocalized electrons and metal cations, that is, an interaction. Part two assessed students' explanation of malleability of metals, for example (a) as a submicro structural rearrangement of metal atoms/cations or (b) based on all-directional electrostatic force. The instrument was validated by the Rasch Model. Psychometric assessment showed that the instrument possessed reasonably good properties of measurement. Results revealed that it was reliable and valid for measuring students' understanding of metallic bonding. Analysis revealed that the structure, process and interaction understandings were unidimensional and in an increasing order of difficulty. Implications for the teaching of metallic bonding, particular through the use of diagrams, critiques and model-based learning, are discussed.

  5. DNA interactions and biocidal activity of metal complexes of ...

    Indian Academy of Sciences (India)

    Narendrula Vamsikrishna

    cancer agents, and the binding between DNA and metal complexes were used in understanding the interaction between the drugs and DNA. In general, the tumour cells can be smashed by stopping the replication of the unnatural DNA. Using Schiff base transition metal complex in particular, affected DNA may be dented by.

  6. Fungal melanins and their interactions with metals.

    Science.gov (United States)

    Fogarty, R V; Tobin, J M

    1996-09-01

    Fungal melanins are dark brown or black pigments located in cell walls. They also exist as extracellular polymers. Melanized fungi possess increased virulence and resistance to microbial attack as well as enhanced survival while under environmental stress. Melanins contain various functional groups which provide an array of multiple nonequivalent binding sites for metal ions. Pigmented Cladosporium cladosporoides was shown to biosorb 2.5- to four-fold more Ni, Cu, Zn, Cd, and Pb than albino Penicillium digitatum and at four- to six-fold higher rates. Metal desorption was significantly lower for extracellular melanin than from pigmented or albino biomass which indicated the strength of the melanin-metal bond. At equilibrium, tributyltin chloride (TBTC) concentrations of 2.5 mM, pigmented and albino Aureobasidium pullulans absorbed approximately 0.9 and 0.7 mumol TBTC mg -1 dry wt, respectively, whereas purified extracellular melanin exhibited uptake levels of approximately 22 mumol TBTC mg-1 dry wt at an equilibrium concentration of only 0.4 mM. Addition of melanin to the growth medium reduced the toxic effect of CuSO4 and TBTC due to melanin metal binding and sequestration.

  7. Dynamic interactions of Leidenfrost droplets on liquid metal surface

    Science.gov (United States)

    Ding, Yujie; Liu, Jing

    2016-09-01

    Leidenfrost dynamic interaction effects of the isopentane droplets on the surface of heated liquid metal were disclosed. Unlike conventional rigid metal, such conductive and deformable liquid metal surface enables the levitating droplets to demonstrate rather abundant and complex dynamics. The Leidenfrost droplets at different diameters present diverse morphologies and behaviors like rotation and oscillation. Depending on the distance between the evaporating droplets, they attract and repulse each other through the curved surfaces beneath them and their vapor flows. With high boiling point up to 2000 °C, liquid metal offers a unique platform for testing the evaporating properties of a wide variety of liquid even solid.

  8. The interaction of hydrogen with metal alloys

    Science.gov (United States)

    Danford, M. D.; Montano, J. W.

    1991-01-01

    Hydrogen diffusion coefficients were measured for several alloys, and these were determined to be about the same at 25 C for all alloys investigated. The relation of structure, both metallurgical and crystallographic, to the observed hydrogen distribution on charging was investigated, as well as the role of hydride formation in the hydrogen resistance of metal alloys. An attempt was made to correlate the structures and compositions of metal alloys as well as other parameters with the ratios of their notched tensile strengths in hydrogen to that in helium, R(H2/He), which are believed to represent a measure of their hydrogen resistance. Evidence supports the belief that hydrogen permeability and hydrogen resistance are increased by smaller grain sizes for a given alloy composition.

  9. Application of a new method for data analysis of isothermal titration calorimetry in the interaction between human serum albumin and Ni2+

    International Nuclear Information System (INIS)

    Saboury, Ali Akbar.

    2003-01-01

    The interaction of human serum albumin (HAS) with divalent nickel ion was studied by isothermal titration calorimetry (ITC) in 30 mM Tris buffer, pH 7.0. There is a set of eight identical and independent binding sites for nickel ions on the protein at the temperature of 300 K. A new calorimetric data analysis allows the determination of the complete set of thermodynamic parameters. The binding isotherm for nickel-HSA interaction is easily obtained by carrying out two different ITC experiments. In the first experiment, the enthalpy of binding for one mole of nickel ion to one mole of binding site on HSA (ΔH=-36.5 kJ) is obtained, and is used in a second experiment to determine the binding isotherm and to find the number of binding sites (g=8) and the equilibrium constant (K=0.57 μM -1 )

  10. Phenytoin-Bovine Serum Albumin interactions - modeling plasma protein - drug binding: A multi-spectroscopy and in silico-based correlation.

    Science.gov (United States)

    Suresh, P K; Divya, Naik; Nidhi, Shah; Rajasekaran, R

    2018-03-15

    The study focused on the analysis of the nature and site of binding of Phenytoin (PHT) -(a model hydrophobic drug) with Bovine Serum Albumin (BSA) (a model protein used as a surrogate for HSA). Interactions with defined amounts of Phenytoin and BSA demonstrated a blue shift (hypsochromic -change in the microenvironment of the tryptophan residue with decrease in the polar environment and more of hydrophobicity) with respect to the albumin protein and a red shift (bathochromic -hydrophobicity and polarity related changes) in the case of the model hydrophobic drug. This shift, albeit lower in magnitude, has been substantiated by a fairly convincing, Phenytoin-mediated quenching of the endogenous fluorophore in BSA. Spectral shifts studied at varying pH, temperatures and incubation periods (at varying concentrations of PHT with a defined/constant BSA concentration) showed no significant differences (data not shown). FTIR analysis provided evidence of the interaction of PHT with BSA with a stretching vibration of 1737.86cm -1 , apart from the vibrations characteristically associated with the amine and carboxyl groups respectively. Our in vitro findings were extended to molecular docking of BSA with PHT (with the different ionized forms of the drug) and the subsequent LIGPLOT-based analysis. In general, a preponderance of hydrophobic interactions was observed. These hydrophobic interactions corroborate the tryptophan-based spectral shifts and the fluorescence quenching data. These results substantiates our hitherto unreported in vitro/in silico experimental flow and provides a basis for screening other hydrophobic drugs in its class. Copyright © 2017. Published by Elsevier B.V.

  11. Comparative studies on the interaction of caffeic acid, chlorogenic acid and ferulic acid with bovine serum albumin

    Science.gov (United States)

    Li, Shuang; Huang, Kelong; Zhong, Ming; Guo, Jun; Wang, Wei-zheng; Zhu, Ronghua

    2010-10-01

    The substitution of the hydrogen on aromatic and esterification of carboxyl group of the phenol compounds plays an important role in their bio-activities. In this paper, caffeic acid (CaA), chlorogenic acid (ChA) and ferulic acid (FA) were selected to investigate the binding to bovine serum albumin (BSA) using UV absorption spectroscopy, fluorescence spectroscopy and synchronous fluorescence spectroscopy. It was found that the methoxyl group substituting for the 3-hydroxyl group of CaA decreased the affinity for BSA and the esterification of carboxyl group of CaA with quinic acid increased the affinities. The affinities of ChA and FA with BSA were more sensitive to the temperature than that of CaA with BSA. Synchronous fluorescence spectroscopy and time-resolved fluorescence indicated that the Stern-Volmer plots largely deviated from linearity at high concentrations and were caused by complete quenching of the tyrosine fluorescence of BSA.

  12. Kaempferol-human serum albumin interaction: Characterization of the induced chirality upon binding by experimental circular dichroism and TDDFT calculations

    Science.gov (United States)

    Matei, Iulia; Ionescu, Sorana; Hillebrand, Mihaela

    2012-10-01

    The experimental induced circular dichroism (ICD) and absorption spectra of the achiral flavonoid kaempferol upon binding to human serum albumin (HSA) were correlated to electronic CD and UV-vis spectra theoretically predicted by time-dependent density functional theory (TDDFT). The neutral and four anionic species of kaempferol in various conformations were considered in the calculations. The appearance of the experimental ICD signal was rationalized in terms of kaempferol binding to HSA in a distorted, chiral, rigid conformation. The comparison between the experimental and simulated spectra allowed for the identification of the kaempferol species that binds to HSA, namely the anion generated by deprotonation of the hydroxyl group in position 7. This approach constitutes a convenient method for evidencing the binding species and for determining its conformation in the binding pocket of the protein. Its main advantage over the UV-vis absorption method lays in the fact that only the bound ligand species gives an ICD signal.

  13. In-vitro displacement interaction of atenolol and amlodipine on binding with bovine serum albumin when co-administered

    Directory of Open Access Journals (Sweden)

    Md. Ashraful Alam, Md. Abdul Awal, Mahbub Mostofa, Md. Kamrul Islam and Nusrat Subhan

    2007-06-01

    Full Text Available The binding of atenolol (selective β1-blocker and amlodipine (calcium channel blocker to bovine serum albumin (BSA was studied by equilibrium dialysis method in order to have an insight into the binding chemistry of these two to BSA. Free atenolol concentration was increased due to addition of amlodipine which reduced the binding of the compounds to BSA. However, the free fraction was increased to a level as it was expected from direct competitive displacement while the free atenolol concentration was increased according to increasing the amlodipine concentration when only the BSA was present. The result obtained when the binding site was blocked by sufficient amount of amlodipine was that the increment of free concentration of atenolol was prominent. When no amlodipine was added the free concentration of atenolol was only 28% whereas this release was 93 % to 98.01% when amlodipine was added with increasing concentration.

  14. Asperity interaction in adhesive contact of metallic rough surfaces

    International Nuclear Information System (INIS)

    Sahoo, Prasanta; Banerjee, Atanu

    2005-01-01

    The analysis of adhesive contact of metallic rough surfaces considering the effect of asperity interaction is the subject of this investigation. The micro-contact model of asperity interactions developed by Zhao and Chang (2001 Trans. ASME: J. Tribol. 123 857-64) is combined with the elastic plastic adhesive contact model developed by Chang et al (1988 Trans. ASME: J. Tribol. 110 50-6) to consider the asperity interaction and elastic-plastic deformation in the presence of surface forces simultaneously. The well-established elastic adhesion index and plasticity index are used to consider the different contact conditions. Results show that asperity interaction influences the load-separation behaviour in elastic-plastic adhesive contact of metallic rough surfaces significantly and, in general, adhesion is reduced due to asperity interactions

  15. Algal-bacterial interactions in metal contaminated floodplain sediments

    International Nuclear Information System (INIS)

    Boivin, M.E.Y.; Greve, G.D.; Garcia-Meza, J.V.; Massieux, B.; Sprenger, W.; Kraak, M.H.S.; Breure, A.M.; Rutgers, M.; Admiraal, W.

    2007-01-01

    The aim of the present study was to investigate algal-bacterial interactions in a gradient of metal contaminated natural sediments. By means of multivariate techniques, we related the genetic structure (denaturing gradient gel electrophoresis, DGGE) and the physiological structure (community-level physiological profiling, CLPP) of the bacterial communities to the species composition of the algal communities and to the abiotic environmental variables, including metal contamination. The results revealed that genetic and physiological structure of the bacterial communities correlated with the species composition of the algal community, but hardly to the level of metal pollution. This must be interpreted as an indication for a strong and species-specific linkage of algal and bacterial species in floodplain sediments. Metals were, however, not proven to affect either the algal or the bacterial communities of the Dutch river floodplains. - Algal and bacterial communities in floodplain sediments are interlinked, but are not affected by metal pollution

  16. Molecular metals with ferromagnetic interaction between localized magnetic moments

    Science.gov (United States)

    Nishijo, J.; Ogura, E.; Yamaura, J.; Miyazaki, A.; Enoki, T.; Takano, T.; Kuwatani, Y.; Iyoda, M.

    2000-11-01

    New charge-transfer salts (EDO-TTFI 2) 2M(mnt) 2 (M=Ni,Pt) are the first organic metals with strong ferromagnetic interactions. These salts consist of one-dimensional chains of EDO-TTFI 2 donors and M(mnt) 2 acceptors aligned in parallel to each other. The metallic conductivity is due to the one dimensional chain of EDO-TTFI 2, and a metal-insulator transition occurs at about 90 K. Localized spins of M(mnt) 2 behave as a one-dimensional ferromagnet, which interact with conduction electrons. The origin of the ferromagnetic interactions are orthogonality of the molecular orbitals of M(mnt) 2 and spin polarization effect which is explained by McConnell's first model.

  17. Spectroscopic characterization of effective components anthraquinones in Chinese medicinal herbs binding with serum albumins

    Science.gov (United States)

    Bi, Shuyun; Song, Daqian; Kan, Yuhe; Xu, Dong; Tian, Yuan; Zhou, Xin; Zhang, Hanqi

    2005-11-01

    The interactions of serum albumins such as human serum albumin (HSA) and bovine serum albumin (BSA) with emodin, rhein, aloe-emodin and aloin were assessed employing fluorescence quenching and absorption spectroscopic techniques. The results obtained revealed that there are relatively strong binding affinity for the four anthraquinones with HSA and BSA and the binding constants for the interactions of anthraquinones with HSA or BSA at 20 °C were obtained. Anthraquinone-albumin interactions were studied at different temperatures and in the presence of some metal ions. And the competition binding of anthraquinones with serum albumins was also discussed. The Stern-Volmer curves suggested that the quenching occurring in the reactions was the static quenching process. The binding distances and transfer efficiencies for each binding reactions were calculated according to the Föster theory of non-radiation energy transfer. Using thermodynamic equations, the main action forces of these reactions were also obtained. The reasons of the different binding affinities for different anthraquinone-albumin reactions were probed from the point of view of molecular structures.

  18. Spin-exchange interaction between transition metals and metalloids in soft-ferromagnetic metallic glasses

    Science.gov (United States)

    Das, Santanu; Choudhary, Kamal; Chernatynskiy, Aleksandr; Choi Yim, Haein; Bandyopadhyay, Asis K.; Mukherjee, Sundeep

    2016-06-01

    High-performance magnetic materials have immense industrial and scientific importance in wide-ranging electronic, electromechanical, and medical device technologies. Metallic glasses with a fully amorphous structure are particularly suited for advanced soft-magnetic applications. However, fundamental scientific understanding is lacking for the spin-exchange interaction between metal and metalloid atoms, which typically constitute a metallic glass. Using an integrated experimental and molecular dynamics approach, we demonstrate the mechanism of electron interaction between transition metals and metalloids. Spin-exchange interactions were investigated for a Fe-Co metallic glass system of composition [(Co1-x Fe x )0.75B0.2Si0.05]96Cr4. The saturation magnetization increased with higher Fe concentration, but the trend significantly deviated from simple rule of mixtures. Ab initio molecular dynamics simulation was used to identify the ferromagnetic/anti-ferromagnetic interaction between the transition metals and metalloids. The overlapping band-structure and density of states represent ‘Stoner type’ magnetization for the amorphous alloys in contrast to ‘Heisenberg type’ in crystalline iron. The enhancement of magnetization by increasing iron was attributed to the interaction between Fe 3d and B 2p bands, which was further validated by valence-band study.

  19. Metal and Metal Oxide Interactions and Their Catalytic Consequences for Oxygen Reduction Reaction

    Energy Technology Data Exchange (ETDEWEB)

    Jia, Qingying; Ghoshal, Shraboni; Li, Jingkun; Liang, Wentao; Meng, Guangnan [ULVAC Technologies, Inc., 401; Che, Haiying [Shanghai; Zhang, Shiming [Shanghai; Ma, Zi-Feng [Shanghai; Mukerjee, Sanjeev

    2017-06-01

    Many industrial catalysts are composed of metal particles supported on metal oxides (MMO). It is known that the catalytic activity of MMO materials is governed by metal and metal oxide interactions (MMOI), but how to optimize MMO systems via manipulation of MMOI remains unclear, due primarily to the ambiguous nature of MMOI. Herein, we develop a Pt/NbOx/C system with tunable structural and electronic properties via a modified arc plasma deposition method. We unravel the nature of MMOI by characterizing this system under reactive conditions utilizing combined electrochemical, microscopy, and in situ spectroscopy. We show that Pt interacts with the Nb in unsaturated NbOx owing to the oxygen deficiency in the MMO interface, whereas Pt interacts with the O in nearly saturated NbOx, and further interacts with Nb when the oxygen atoms penetrate into the Pt cluster at elevated potentials. While the Pt–Nb interactions do not benefit the inherent activity of Pt toward oxygen reduction reaction (ORR), the Pt–O interactions improve the ORR activity by shortening the Pt–Pt bond distance. Pt donates electrons to NbOx in both Pt–Nb and Pt–O cases. The resultant electron efficiency stabilizes low-coordinated Pt sites, hereby stabilizing small Pt particles. This determines the two characteristic features of MMO systems: dispersion of small metal particles and high catalytic durability. These findings contribute to our understandings of MMO catalytic systems.

  20. Ultrasound-assisted interaction between chlorin-e6 and human serum albumin: pH dependence, singlet oxygen production, and formulation effect

    Science.gov (United States)

    Mocanu, Mihaela N.; Yan, Fei

    2018-02-01

    The interaction between chlorin e6 (Ce6) and human serum albumin (HSA) in the presence and absence of ultrasound have been investigated by ultraviolet-visible absorption spectroscopy and fluorescence spectroscopy. Ce6 is found to bind strongly to HSA at or near physiological pH conditions, but the strength of the binding is significantly weakened at lower pHs. The intrinsic fluorescence of HSA is incrementally quenched with increasing concentration of Ce6, and the quenching is enhanced after exposure to high-frequency ultrasound. Our experimental results suggest that Ce6-induced sonodynamic oxidation of HSA is mainly mediated by singlet oxygen. The formulation of Ce6 by high molecular weight polyvinylpyrrolidone (PVP) increased its stability in aqueous solutions and its quantum yield of singlet oxygen under ultrasound irradiation.

  1. Determination of correlation times from selective and non-selective spin-lattice relaxation rates and their use in drug-drug and drug-albumin interaction studies

    Directory of Open Access Journals (Sweden)

    Tinoco Luzineide Wanderley

    1999-01-01

    Full Text Available The effects of the changes in sample concentration on the NMR chemical shifts and on the selective and non-selective spin-lattice relaxation rates (R1S and R1NS of the three isomers of nitrobenzaldeyde guanyl hydrazone (NBGH pure and with bovine serum albumin (BSA were measured in solution. The results wereused to determine the correlation times (tauc, showing that the degree of intermolecular drug-drug association varies with the nitro group position on the ring and that this degree of association interferes with the interaction of these drugs with BSA. The results suggest that the degree of drug-drug and drug-BSA association are related to the in vitro anti-Trypanosoma cruzi activity of these compounds.

  2. Interaction of 2-(9H-purin-6-ylamino)-4-(methylthio) butanoic acid with human serum albumin: fluorescence and modeling studies.

    Science.gov (United States)

    Cui, Fengling; Yan, Yinghua; Zhang, Qiangzhai; Du, Juan; Yao, Xiaojun; Qu, Guirong; Lu, Yan

    2010-01-01

    This study was designed to investigate the interaction between (S)-2-(9H-purin-6-ylamino)-4-(methylthio) butanoic acid (PYMBA) and human serum albumin (HSA) using fluorescence spectroscopy. The combination of UV absorption and molecular docking under simulative physiological conditions was also applied to comprehensively understand the binding mechanism of PYMBA to HSA. Fluorescence data indicated that PYMBA has a strong ability to quench the intrinsic fluorescence of HSA. The binding constants (K) at different temperatures, thermodynamic parameters including enthalpy change (DeltaH) and entropy change (DeltaS) of PYMBA-HSA were correlated to the relevant fluorescence data, which suggested that the hydrophobic force played a very important role for the PYMBA binding to the HSA. The experimental results were in agreement with the results obtained via a molecular docking study. The effects of other ions on the binding constants were also studied.

  3. From guest to ligand - A study on the competing interactions of antitumor drug resveratrol with {beta}-cyclodextrin and bovine serum albumin

    Energy Technology Data Exchange (ETDEWEB)

    Li, Xudong [College of Chemistry and Chemical Engineering, Liaocheng University, Liaocheng, Shandong Province 252059 (China); Department of Clinical Laboratory, Liaocheng People' s Hospital, Liaocheng, Shandong Province 252000 (China); Li, Hui [College of Chemistry and Chemical Engineering, Liaocheng University, Liaocheng, Shandong Province 252059 (China); Liu, Min, E-mail: liumin_panpan@163.com [College of Chemistry and Chemical Engineering, Liaocheng University, Liaocheng, Shandong Province 252059 (China); Li, Guangqian; Li, Linwei [College of Chemistry and Chemical Engineering, Liaocheng University, Liaocheng, Shandong Province 252059 (China); Sun, Dezhi, E-mail: sundezhisdz@163.com [College of Chemistry and Chemical Engineering, Liaocheng University, Liaocheng, Shandong Province 252059 (China)

    2011-07-10

    Graphical abstract: Thermodynamic behavior of the interaction between bovine serum albumin and antitumor drug resveratrol delivered by {beta}-cyclodextrin in buffer solutions (pH 7.40) have been investigated by ITC combined with UV, FS and circular dichroism at 298.15 K. The results indicated that the affinity of resveratrol with the host ({beta}-cyclodextrin) was evidently weaker than that of the drug with the both classes of binding sites on the protein molecule. Highlights: {yields} Supramolecular complex of a drug with BSA could form in aqueous medium. {yields} A set of thermodynamic parameters were determined. {yields} Affinity of the drug to {beta}-CD is weaker than that of it to the protein. {yields} The molecular conformation of BSA was (slightly) changed by the drug. - Abstract: Interaction between bovine serum albumin (BSA) and resveratrol (RES) included by {beta}-cyclodextrin ({beta}-CD) in Tris-HCl aqueous buffer solutions (pH 7.4) has been investigated by isothermal titration calorimetry (ITC) combined with ultraviolet, fluorescence and circular dichroism spectra analyses. The results indicate that there are two classes of ligand binding sites. The first class of binding is mainly driven by enthalpy, while the second one is driven by both enthalpy and entropy. The secondary structure of BSA in the aqueous system was slightly changed with addition of the drug. Thermodynamic parameters, i.e., equilibrium constants, standard enthalpy changes and the entropy effects for the binding process of RES with BSA were calculated based on the calorimetric data. In fact, due to the poor solubility of RES in aqueous buffer medium, these parameters could not be determined by the employed experimental method without the existence of the CD.

  4. The standard molar enthalpy of formation of a new copper(II) Schiff-base complex and its interaction with bovine serum albumin

    Energy Technology Data Exchange (ETDEWEB)

    Xie, Jin-Qi [Hunan Provincial Key Laboratory of Xiangnan Rare-Precious Metals Compounds and Applications, Department of Chemistry and Life Science, Xiangnan University, Chenzhou 423000, Hunan (China); Li, Chuan-Hua, E-mail: lichuanhua0526@126.com [Hunan Provincial Key Laboratory of Xiangnan Rare-Precious Metals Compounds and Applications, Department of Chemistry and Life Science, Xiangnan University, Chenzhou 423000, Hunan (China); Dong, Jia-Xin [School of Chemistry and Pharmaceutical Sciences, Guangxi Normal University, Guilin 541004 (China); Qu, Wei; Pan, Lan; Peng, Meng-La; Xie, Ming-An; Tao, Xu; Yu, Cheng-Mao; Zhu, Yi; Zhang, Ping-Hua; Tang, Chun-Guang [Hunan Provincial Key Laboratory of Xiangnan Rare-Precious Metals Compounds and Applications, Department of Chemistry and Life Science, Xiangnan University, Chenzhou 423000, Hunan (China); Li, Qiang-Guo, E-mail: liqiangguo@163.com [Hunan Provincial Key Laboratory of Xiangnan Rare-Precious Metals Compounds and Applications, Department of Chemistry and Life Science, Xiangnan University, Chenzhou 423000, Hunan (China)

    2014-12-20

    Highlights: • A new copper(II) Valen Schiff-base complex was synthesized and characterized. • The standard molar enthalpy of formation of the title complex was obtained. • The interaction between the complex and bovine serum albumin was investigated. - Abstract: A new copper(II) Schiff-base complex [Cu(HL)·NO{sub 3}·MeOH] was prepared by using equivalent molar of Valen Schiff-base ligand [H{sub 2}L=N,N′-ethylene-bis(3-methoxysalicylideneimine)] and Cu(NO{sub 3}){sub 2}·3H{sub 2}O. The structure of the complex was confirmed by single-crystal X-ray diffraction. Based on an ideal and feasible thermochemical cycle, the standard molar enthalpy of formation of the complex was estimated to be: Δ{sub f}H{sub m}{sup θ} [Cu(HL)·NO{sub 3}·MeOH(s), 298.15 K] = –(945.40 ± 2.44) kJ mol{sup −1} by an advanced solution-reaction isoperibol calorimeter. In particular, the interaction between the complex and bovine serum albumin (BSA) was investigated using the fluorescence quenching method. Fluorescence quenching data showed that the quenching mechanism of BSA treated by the complex was static quenching, which was highly accord with the non-radioactive energy transfer theory. And some relevant parameters such as binding sites, binding distance and intermolecular forces between the complex and BSA were also obtained by analyzing the fluorescence spectral data.

  5. Affinity capillary electrophoresis and fluorescence spectroscopy for studying enantioselective interactions between omeprazole enantiomer and human serum albumin.

    Science.gov (United States)

    Xu, Yujing; Hong, Tingting; Chen, Xueping; Ji, Yibing

    2017-05-01

    Baseline separation of omeprazole (OME) enantiomers was achieved by affinity capillary electrophoresis (ACE), using human serum albumin (HSA) as the chiral selector. The influence of several experimental variables such as HSA concentration, the type and content of organic modifiers, applied voltage and running buffer concentration on the separation was evaluated. The binding of esomeprazole (S-omeprazole, S-OME) and its R-enantiomer (R-omeprazole, R-OME) to HSA under simulated physiological conditions was studied by ACE and fluorescence spectroscopy which was considered as a reference method. ACE studies demonstrated that the binding constants of the two enantiomers and HSA were 3.18 × 10 3 M -1 and 5.36 × 10 3 M -1 , respectively. The binding properties including the fluorescence quenching mechanisms, binding constants, binding sites and the number of binding sites were obtained by fluorescence spectroscopy. Though the ACE method could not get enough data when compared with the fluorescence spectrum method, the separation and binding studies of chiral drugs could be achieved simultaneously via this method. This study is of great significance for the investigation and clinical application of chiral drugs. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Human serum albumin interactions with C{sub 60} fullerene studied by spectroscopy, small-angle neutron scattering, and molecular dynamics simulations

    Energy Technology Data Exchange (ETDEWEB)

    Li, Song [Vanderbilt University, Department of Chemical and Biomolecular Engineering (United States); Zhao, Xiongce [NIDDK, National Institutes of Health (United States); Mo, Yiming [Institute of Agriculture, University of Tennessee (United States); Cummings, Peter T., E-mail: cummingspt@ornl.gov [Vanderbilt University, Department of Chemical and Biomolecular Engineering (United States); Heller, William T., E-mail: hellerwt@ornl.gov [Oak Ridge National Laboratory, Center for Structural Molecular Biology (United States)

    2013-07-15

    Concern about the toxicity of engineered nanoparticles, such as the prototypical nanomaterial C{sub 60} fullerene, continues to grow. While, evidence continues to mount that C{sub 60} and its derivatives may pose health hazards, the specific molecular interactions of these particles with biological macromolecules require further investigation. In this article, we report combined experimental and theoretical studies on the interaction of one of the most prevalent proteins in the human body, human serum albumin (HSA), with C{sub 60} in an aqueous environment. The C{sub 60}-HSA interaction was probed by circular dichroism (CD) spectroscopy, small-angle neutron scattering (SANS), and atomistic molecular dynamics (MD) simulations to understand C{sub 60}-driven changes in the structure of HSA in solution. The CD spectroscopy demonstrates that the secondary structure of the protein decreases in {alpha}-helical content in response to the presence of C{sub 60} (0.68 nm in diameter). Similarly, C{sub 60} produces subtle changes in the solution conformation of HSA (an 8.0 nm Multiplication-Sign 3.8 nm protein), as evidenced by the SANS data and MD simulations, but the data do not indicate that C{sub 60} changes the oligomerization state of the protein, such as by inducing aggregation. The results demonstrate that the interaction is not highly disruptive to the protein in a manner that would prevent it from performing its physiological function.

  7. Penetrable silica microspheres for immobilization of bovine serum albumin and their application to the study of the interaction between imatinib mesylate and protein by frontal affinity chromatography.

    Science.gov (United States)

    Ma, Liyun; Li, Jing; Zhao, Juan; Liao, Han; Xu, Li; Shi, Zhi-guo

    2016-01-01

    In the current study, novel featured silica, named penetrable silica, simultaneously containing macropores and mesopores, was immobilized with bovine serum albumin (BSA) via Schiff base method. The obtained BSA-SiO2 was employed as the high-performance liquid chromatographic (HPLC) stationary phase. Firstly, D- and L-tryptophan were used as probes to investigate the chiral separation ability of the BSA-SiO2 stationary phase. An excellent enantioseparation factor was obtained up to 4.3 with acceptable stability within at least 1 month. Next, the BSA-SiO2 stationary phase was applied to study the interaction between imatinib mesylate (IM) and BSA by frontal affinity chromatography. A single type of binding site was found for IM with the immobilized BSA, and the hydrogen-bonding and van der Waals interactions were expected to be contributing interactions based on the thermodynamic studies, and this was a spontaneous process. Compared to the traditional silica for HPLC stationary phase, the proposed penetrable silica microsphere possessed a larger capacity to bond more BSA, minimizing column overloading effects and enhancing enantioseparation ability. In addition, the lower running column back pressure and fast mass transfer were meaningful for the column stability and lifetime. It was a good substrate to immobilize biomolecules for fast chiral resolution and screening drug-protein interactions.

  8. Albumin-based drug delivery

    DEFF Research Database (Denmark)

    Larsen, Maja Thim; Kuhlmann, Matthias; Hvam, Michael Lykke

    2016-01-01

    The effectiveness of a drug is dependent on accumulation at the site of action at therapeutic levels, however, challenges such as rapid renal clearance, degradation or non-specific accumulation requires drug delivery enabling technologies. Albumin is a natural transport protein with multiple ligand...... binding sites, cellular receptor engagement, and a long circulatory half-life due to interaction with the recycling neonatal Fc receptor. Exploitation of these properties promotes albumin as an attractive candidate for half-life extension and targeted intracellular delivery of drugs attached by covalent...... conjugation, genetic fusions, association or ligand-mediated association. This review will give an overview of albumin-based products with focus on the natural biological properties and molecular interactions that can be harnessed for the design of a next-generation drug delivery platform....

  9. Molecular Indicators of Soil Humification and Interaction with Heavy Metals

    Energy Technology Data Exchange (ETDEWEB)

    Fan, Teresa W.-M.; Higashi, Richard M.; Cassel, Teresa; Green, Peter; Lane, Andrew N.

    2003-03-26

    For stabilization of heavy metals at contaminated sites, interaction of soil organic matter (SOM) with heavy metal ions is critically important for long-term sustainability, a factor that is poorly understood at the molecular level. Using 13C- and 15N-labeled soil humates (HS), we investigated the turnover of five organic amendments (celluose, wheat straw, pine shavings, chitin and bone meal) in relation to heavy metal ion leaching in soil column experiments. The labeled molecular substructures in HS were examined by multinuclear 2-D NMR and pyrolysis GC-MS while the element profile in the leachates was analyzed by ICP-MS. Preliminary analysis revealed that peptidic and polysaccharidic structures were highly enriched, which suggests their microbial origin. Cd(II) leaching was significantly attenuated with humification of lignocellulosic materials. Correlation of 13C and 15N turnovers of HS substructures to metal leaching is underway.

  10. Interaction of bovine serum albumin and human blood plasma with PEO-tethered surfaces: Influence of PEO chain length, grafting density, and temperature : Influence of PEO chain length, grafting density, and temperature

    NARCIS (Netherlands)

    Norde, Willem; Gage, D.

    2004-01-01

    Solid surfaces are modified by grafting poly(ethylene oxide), PEO, to influence their interaction with indwelling particles, in particular molecules of bovine serum albumin and human plasma proteins. As a rule, the grafted PEO layers suppress protein adsorption. The suppression is most effective

  11. Transmission electron microscopy and time resolved optical spectroscopy study of the electronic and structural interactions of ZnO nanorods with bovine serum albumin.

    Science.gov (United States)

    Klaumünzer, M; Weichsel, U; Mačković, M; Spiecker, E; Peukert, W; Kryschi, C

    2013-08-22

    The adsorption behavior and electronic interactions of bovine serum albumin (BSA) with ZnO nanorod surfaces were investigated using high-resolution transmission electron microscopy as well as stationary and time-resolved optical spectroscopy techniques. Transmission electron microscopy shows that ZnO nanorod surfaces are surrounded by a homogeneous amorphous BSA film with thicknesses between ~2.5 and 5.0 nm. The electronic structure and adsorption geometry of BSA were examined using high-angle annular dark field scanning transmission electron microscopy combined with electron energy loss spectroscopy. The adsorption process was observed to result into an unfolded conformation of BSA becoming predominantly bound in the side-on orientation at the ZnO surface. This adsorption mode of the BSA molecules allows for a strong interaction with surface states of the ZnO nanorods. This is obvious from its efficient quenching of the defect-center photoluminescence of ZnO. Complementary information of electronic interactions across the ZnO nanorod interface was obtained from femtosecond transient absorption spectroscopy experiments. The rise dynamics of the measured transients revealed altered hole trapping dynamics and, thus, indicated to heterogeneous charge transfer as emerging from adsorbed BSA molecules to defect centers of the ZnO interface.

  12. Analysis of the interactions between human serum albumin/amphiphilic penicillin in different aqueous media: an isothermal titration calorimetry and dynamic light scattering study

    International Nuclear Information System (INIS)

    Barbosa, Silvia; Taboada, Pablo; Mosquera, Victor

    2005-01-01

    The complexation process of the amphiphilic penicillins sodium cloxacillin and sodium dicloxacillin with the protein human serum albumin (HSA) in aqueous buffered solutions of pH 4.5 and 7.4 at 25 o C was investigated through isothermal titration calorimetry (ITC) and dynamic light scattering. ITC experiments were carried out in the very dilute regime and showed that although hydrophobic interactions are the leading forces for complexation, electrostatic interactions also play an important role. The possibility of the formation of hydrogen bonds is also deduced from experimental data. The thermodynamic quantities of the binding mechanism, i.e, the enthalpy, ΔHITCi, entropy, ΔSITCi, Gibbs energy, ΔGITCi, binding constant, KITCi and the number of binding sites, n i , were obtained. The binding was saturable and is characterised by Langmuir adsorption isotherms. From ITC data and following a theoretical model, the number of bound and free penicillin molecules was calculated. From Scatchard plots, KITCi and n i were obtained and compared with those from ITC data. The interaction potential between the HSA-penicillin complexes and their stability were determined at pH 7.4 from the dependence of the diffusion coefficients on protein concentration by application of the DLVO colloidal stability theory. The results indicate decreasing stability of the colloidal dispersion of the drug-protein complexes with increase in the concentration of added drug

  13. Analysis of the Interaction of Dp44mT with Human Serum Albumin and Calf Thymus DNA Using Molecular Docking and Spectroscopic Techniques

    Directory of Open Access Journals (Sweden)

    Zhongjie Xu

    2016-06-01

    Full Text Available Di-2-pyridylketone-4,4,-dimethyl-3-thiosemicarbazone (Dp44mT exhibits significant antitumor activity. However, the mechanism of its pharmacological interaction with human serum albumin (HSA and DNA remains poorly understood. Here, we aimed to elucidate the interactions of Dp44mT with HSA and DNA using MTT assays, spectroscopic methods, and molecular docking analysis. Our results indicated that addition of HSA at a ratio of 1:1 did not alter the cytotoxicity of Dp44mT, but did affect the cytotoxicity of the Dp44mT-Cu complex. Data from fluorescence quenching and UV-VIS absorbance measurements demonstrated that Dp44mT could bind to HSA with a moderate affinity (Ka = approximately 104 M−1. CD spectra revealed that Dp44mT could slightly disrupt the secondary structure of HSA. Dp44mT could also interact with Ct-DNA, but had a moderate binding constant (KEB = approximately 104 M−1. Docking studies indicated that the IB site of HSA, but not the IIA and IIIA sites, could be favorable for Dp44mT and that binding of Dp44mT to HSA involved hydrogen bonds and hydrophobic force, consistent with thermodynamic results from spectral investigations. Thus, the moderate binding affinity of Dp44mT with HSA and DNA partially contributed to its antitumor activity and may be preferable in drug design approaches.

  14. Surface/structure functionalization of copper-based catalysts by metal-support and/or metal-metal interactions

    Science.gov (United States)

    Konsolakis, Michalis; Ioakeimidis, Zisis

    2014-11-01

    Cu-based catalysts have recently attracted great attention both in catalysis and electro-catalysis fields due to their excellent catalytic performance and low cost. Given that their performance is determined, to a great extent, by Cu sites local environment, considerable efforts have been devoted on the strategic modifications of the electronic and structural properties of Cu sites. In this regard, the feasibility of tuning the local structure of Cu entities by means of metal-support or metal-metal interactions is investigated. More specifically, the physicochemical properties of Cu entities are modified by employing: (i) different oxides (CeO2, La2O3, Sm2O3), or (ii) ceria-based mixed oxides (Ce1-xSmxOδ) as supporting carriers, and (iii) a second metal (Cobalt) adjacent to Cu (bimetallic Cu-Co/CeO2). A characterization study, involving BET, XRD, TPR, and XPS, reveal that significant modifications on structural, redox and electronic properties of Cu sites can be induced by adopting either different oxide carriers or bimetallic complexes. Fundamental insights into the tuning of Cu local environment by metal-support or metal-metal interactions are provided, paving the way for real-life industrial applications.

  15. Metals interaction in the process of torch mass transfer

    International Nuclear Information System (INIS)

    Khaldeev, V.N.; Pashko, O.V.; Belova, V.P.; Sevryugina, N.D.; Vasil'eva, A.I.

    2000-01-01

    The billet material components interaction with the work surface material of the electrode-tool under the action of a torch jet which is formed in the process of electro-erosion treatment is investigated. It is established that metallic film arises on a surface of the electrode-tool under certain conditions in the process of electro-erosion forming is identical with the composition of the worked material. Components of the metal alloy worked diffuse into the tool material with formation of a particular compounds [ru

  16. In vitro study on binding interaction of quinapril with bovine serum albumin (BSA) using multi-spectroscopic and molecular docking methods.

    Science.gov (United States)

    Shi, Jie-Hua; Pan, Dong-Qi; Jiang, Min; Liu, Ting-Ting; Wang, Qi

    2017-08-01

    The binding interaction between quinapril (QNPL) and bovine serum albumin (BSA) in vitro has been investigated using UV absorption spectroscopy, steady-state fluorescence spectroscopic, synchronous fluorescence spectroscopy, 3D fluorescence spectroscopy, Fourier transform infrared spectroscopy, circular dichroism, and molecular docking methods for obtaining the binding information of QNPL with BSA. The experimental results confirm that the quenching mechanism of the intrinsic fluorescence of BSA induced by QNPL is static quenching based on the decrease in the quenching constants of BSA in the presence of QNPL with the increase in temperature and the quenching rates of BSA larger than 10 10  L mol -1  s -1 , indicating forming QNPL-BSA complex through the intermolecular binding interaction. The binding constant for the QNPL-BSA complex is in the order of 10 5  M -1 , indicating there is stronger binding interaction of QNPL with BSA. The analysis of thermodynamic parameters together with molecular docking study reveal that the main binding forces in the binding process of QNPL with BSA are van der Waal's forces and hydrogen bonding interaction. And, the binding interaction of BSA with QNPL is an enthalpy-driven process. Based on Förster resonance energy transfer, the binding distance between QNPL and BSA is calculated to be 2.76 nm. The results of the competitive binding experiments and molecular docking confirm that QNPL binds to sub-domain IIA (site I) of BSA. It is confirmed there is a slight change in the conformation of BSA after binding QNPL, but BSA still retains its secondary structure α-helicity.

  17. Some Case Studies on Metal-Microbe Interactions to Remediate Heavy Metals- Contaminated Soils in Korea

    Science.gov (United States)

    Chon, Hyo-Taek

    2015-04-01

    Conventional physicochemical technologies to remediate heavy metals-contaminated soil have many problems such as low efficiency, high cost and occurrence of byproducts. Recently bioremediation technology is getting more and more attention. Bioremediation is defined as the use of biological methods to remediate and/or restore the contaminated land. The objectives of bioremediation are to degrade hazardous organic contaminants and to convert hazardous inorganic contaminants to less toxic compounds of safe levels. The use of bioremediation in the treatment of heavy metals in soils is a relatively new concept. Bioremediation using microbes has been developed to remove toxic heavy metals from contaminated soils in laboratory scale to the contaminated field sites. Recently the application of cost-effective and environment-friendly bioremediation technology to the heavy metals-contaminated sites has been gradually realized in Korea. The merits of bioremediation include low cost, natural process, minimal exposure to the contaminants, and minimum amount of equipment. The limitations of bioremediation are length of remediation, long monitoring time, and, sometimes, toxicity of byproducts for especially organic contaminants. From now on, it is necessary to prove applicability of the technologies to contaminated sites and to establish highly effective, low-cost and easy bioremediation technology. Four categories of metal-microbe interactions are generally biosorption, bioreduction, biomineralization and bioleaching. In this paper, some case studies of the above metal-microbe interactions in author's lab which were published recently in domestic and international journals will be introduced and summarized.

  18. Binding investigation on the interaction between Methylene Blue (MB)/TiO2 nanocomposites and bovine serum albumin by resonance light-scattering (RLS) technique and fluorescence spectroscopy.

    Science.gov (United States)

    Li, Yuesheng; Zhang, Yue; Sun, Shaofa; Zhang, Aiqing; Liu, Yi

    2013-11-05

    The interaction between Methylene Blue (MB)/TiO2 nanocomposites and bovine serum albumin (BSA) was investigated by resonance light scattering (RLS), fluorescence, three-dimension spectra and UV-vis absorbance spectroscopy. Several factors which may influence the RLS intensity were also investigated before characterizing MB/TiO2-BSA complex. It was proved that the mechanism of MB/TiO2 nanocomposites binding to BSA was mainly a result of the formation of MB/TiO2-BSA complex. The binding constant of MB/TiO2-BSA is 0.762 × 10(-5) L mol(-1) at 298K. By calculating the binding constant at different temperature, the thermodynamic parameters ΔH, ΔG, and ΔS can be observed and deduced that the hydrophobic interactions played an important role to stabilize the complex. The distance r (3.73 nm) between donor (BSA) and acceptor (MB/TiO2) was obtained according to fluorescence resonance energy transfer (FRET). The binding site for MB/TiO2 on BSA was mainly located in sub-domain IIA. The UV-vis absorbance, circular dichroism and three dimension fluorescence have also been used to investigate the effect of MB/TiO2 on the conformation of BSA. Copyright © 2013 Elsevier B.V. All rights reserved.

  19. Characterizing the binding interaction of fungicide boscalid with bovine serum albumin (BSA): A spectroscopic study in combination with molecular docking approach.

    Science.gov (United States)

    Lou, Yan-Yue; Zhou, Kai-Li; Shi, Jie-Hua; Pan, Dong-Qi

    2017-08-01

    Boscalid, a carboxamide fungicide, is used in the treatment of grey mould and powdery mildew, widely applied to a variety of crops and fruits such as rice, wheat, grapes and pears. It will become a potential risk for health due to its widely application and residue in crops and fruits. In this study, the binding interaction between boscalid and bovine serum albumin (BSA) was characterized using steady-state fluorescence spectroscopy, ultraviolet spectroscopy (UV), synchronous fluorescence spectroscopy, 3D fluorescence spectroscopy, Fourier transform infrared spectroscopy (FT-IR) and molecular docking to ascertain the store, transport and distribution of boscalid in vivo. The experimental results indicated that the fluorescence of BSA was quenched due to the forming the static boscalid-BSA complex with the binding constant of 4.57×10 3 M -1 at 298 K and boscalid bound on the subdomain III A (site II) of BSA through van der Waals force and hydrogen bonding interaction. The binding process of boscalid with BSA was spontaneous and enthalpy-driven process based on ΔG 0 T|ΔS 0 | over the studied temperature range. Meanwhile, the obvious change in the conformation of boscalid was observed while the slight change in the conformation of BSA when binding boscalid to the BSA, implying that the flexibility of boscalid contributes to increasing the stability of the boscalid-BSA complex. Copyright © 2017 Elsevier B.V. All rights reserved.

  20. Domain-specific interactions between MLN8237 and human serum albumin estimated by STD and WaterLOGSY NMR, ITC, spectroscopic, and docking techniques

    Science.gov (United States)

    Yang, Hongqin; Liu, Jiuyang; Huang, Yanmei; Gao, Rui; Tang, Bin; Li, Shanshan; He, Jiawei; Li, Hui

    2017-03-01

    Alisertib (MLN8237) is an orally administered inhibitor of Aurora A kinase. This small-molecule inhibitor is under clinical or pre-clinical phase for the treatment of advanced malignancies. The present study provides a detailed characterization of the interaction of MLN8237 with a drug transport protein called human serum albumin (HSA). STD and WaterLOGSY nuclear magnetic resonance (NMR)-binding studies were conducted first to confirm the binding of MLN8237 to HSA. In the ligand orientation assay, the binding sites of MLN8237 were validated through two site-specific spy molecules (warfarin sodium and ibuprofen, which are two known site-selective probes) by using STD and WaterLOGSY NMR competition techniques. These competition experiments demonstrate that both spy molecules do not compete with MLN8237 for the specific binding site. The AutoDock-based blind docking study recognizes the hydrophobic subdomain IB of the protein as the probable binding site for MLN8237. Thermodynamic investigations by isothermal titration calorimetry (ITC) reveal that the non-covalent interaction between MLN8237 and HSA (binding constant was approximately 105 M-1) is driven mainly by favorable entropy and unfavorable enthalpy. In addition, synchronous fluorescence, circular dichroism (CD), and 3D fluorescence spectroscopy suggest that MLN8237 may induce conformational changes in HSA.

  1. Probing the Interaction of Human Serum Albumin with Norfloxacin in the Presence of High-Frequency Electromagnetic Fields: Fluorescence Spectroscopy and Circular Dichroism Investigations

    Directory of Open Access Journals (Sweden)

    Jamshidkhan Chamani

    2011-11-01

    Full Text Available The present study describes an investigation by fluorescence quenching, circular dichroism and UV-visible spectroscopy of the interaction between norfloxacin (NRF and human serum albumin (HSA in the presence of electromagnetic fields (EMFs. The results obtained from this study indicated that NRF had a strong ability to quench HSA at λex = 280 nm. In addition, a slight blue shift occurred, which suggested that the microenvironment of the protein became more hydrophobic after addition of NRF. The interaction between the NRF and HSA, whether in the absence or presence of an EMF, was considered to be a static quenching mechanism. Moreover, synchronous fluorescence demonstrated that the microenvironment around Trp became modified. Data of HSA-NRF in the presence of EMFs between 1 Hz–1 MHz confirmed the results of quenching and blue shifts. Corresponding Stern-Volmer plots were also drawn and the resultant Ksv and kq values were compared. Moreover, the binding parameters, including the number of binding sites, the binding constant and the distance, r, between donor and acceptor, were calculated based on Förster’s non-radiative energy transfer theory. According to far and near UV-CD, the formation of the complex caused changes of the secondary and tertiary structures of HSA. The obtained results are significant for patients who are subjected to high-frequency radiation as this was found to reduce the affinity of NRF to HSA.

  2. Biophysical characterization of the interaction between human serum albumin and n-dodecyl β-D-maltoside: A multi-technique approach.

    Science.gov (United States)

    Ali, Mohd Sajid; Al-Lohedan, Hamad A

    2015-10-01

    We have studied the effect of biocompatible sugar based surfactant n-dodecyl β-D-maltoside (DDM) on the conformation of human serum albumin (HSA). A multi-technique approach was applied in order to understand the type of interaction and effect of DDM on the secondary and tertiary structure of HSA. Surface tension measurement showed that HSA shifted the critical micelle concentration (cmc) of the surfactant to the higher side that clarifies the complex formation between DDM and HSA which was also confirmed by UV absorption spectroscopy. Fluorescence quenching measurements showed that fluorescence of HSA was quenched by the addition of DDM with a prominent blue shift indicative of the involvement of hydrophobic interaction which was further confirmed by extrinsic fluorescence of organic dye 1-anilino-8-naphthalenesulfonate. Synchronous fluorescence measurement trends suggested that the hydrophobicity increases near the tryptophan residue while an increase in the polarity was observed near tyrosine residues. A collective information obtained by circular dicroism (CD) and Fourier-transform infra-red (FTIR) spectroscopies along with dynamic light scattering revealed the partial unfolding of the protein. Copyright © 2015 Elsevier B.V. All rights reserved.

  3. Interaction between ropinirole hydrochloride and aspirin with human serum albumin as binary and ternary systems by multi-spectroscopic, molecular modeling and zeta potential

    International Nuclear Information System (INIS)

    Mahaki, Hanie; Memarpoor-Yazdi, Mina; Chamani, Jamshidkhan; Reza Saberi, Mohammad

    2013-01-01

    The aim of the present study was to describe the competition of ropinirole hydrochloride (RP) and aspirin (ASA) in binding to human serum albumin (HSA) in physiological buffer (pH=7.4) using multi-spectroscopic, molecular modeling and zeta-potential measurements. Fluorescence analysis was used to define the binding and quenching properties of drug-HSA complexes in binary and ternary systems. Fluorescence spectroscopy showed that in the presence of RP, the binding constant of HSA–ASA was increased. Static quenching was confirmed to result in the fluorescence quenching and FRET. The effect of drugs on the conformation of HSA was analyzed using synchronous fluorescence spectroscopy, three-dimensional fluorescence spectra and circular dichroism (CD). The RLS method determined the critical aggregation concentration of drugs on HSA in binary and ternary systems that confirmed the zeta potential results. Structural modeling showed that the affinity of each of the drugs to HSA in binary and ternary systems confirms the spectroscopic results. - Highlights: ► We studied the interaction of ropinirole hydrochloride and aspirin with HSA. ► Molecular modeling and zeta-potential used to describe competitive interaction. ► We determined the critical induced aggregation concentration of both drugs on HSA. ► The binding mechanism of drugs as separate and simultaneous to HSA has been compared. ► The binding site of both drugs as simultaneous effects on HSA has been determined.

  4. Studies of the Interaction between Isoimperatorin and Human Serum Albumin by Multispectroscopic Method: Identification of Possible Binding Site of the Compound Using Esterase Activity of the Protein

    Directory of Open Access Journals (Sweden)

    Samira Ranjbar

    2013-01-01

    Full Text Available Isoimperatorin is one of the main components of Prangos ferulacea as a linear furanocoumarin and used as anti-inflammatory, analgesic, antispasmodic, and anticancer drug. Human serum albumin (HSA is a principal extracellular protein with a high concentration in blood plasma and carrier for many drugs to different molecular targets. Since the carrying of drug by HSA may affect on its structure and action, we decided to investigate the interaction between HSA and isoimperatorin using fluorescence and UV spectroscopy. Fluorescence data indicated that isoimperatorin quenches the intrinsic fluorescence of the HSA via a static mechanism and hydrophobic interaction play the major role in the drug binding. The binding average distance between isoimperatorin and Trp 214 of HSA was estimated on the basis of the theory of Förster energy transfer. Decrease of protein surface hydrophobicity (PSH was also documented upon isoimperatorin binding. Furthermore, the synchronous fluorescence spectra show that the microenvironment of the tryptophan residues does not have obvious changes. Site marker compettive and fluorescence experiments revealed that the binding of isoimperatorin to HSA occurred at or near site I. Finally, the binding details between isoimperatorin and HSA were further confirmed by molecular docking and esterase activity inhibition studies which revealed that drug was bound at subdomain IIA.

  5. Probing the interaction of thionine with human serum albumin by multispectroscopic studies and its in vitro cytotoxic activity toward MCF-7 breast cancer cells.

    Science.gov (United States)

    Manivel, Perumal; Paulpandi, Manickam; Murugan, Kadarkarai; Benelli, Giovanni; Ilanchelian, Malaichamy

    2017-11-01

    The studies on protein-dye interactions are important in biological process and it is regarded as vital step in rational drug design. The interaction of thionine (TH) with human serum albumin (HSA) was analyzed using isothermal titration calorimetry (ITC), spectroscopic, and molecular docking technique. The emission spectral titration of HSA with TH revealed the formation of HSA-TH complex via static quenching process. The results obtained from absorption, synchronous emission, circular dichroism, and three-dimensional (3D) emission spectral studies demonstrated that TH induces changes in the microenvironment and secondary structure of HSA. Results from ITC experiments suggested that the binding of TH dye was favored by negative enthalpy and a favorable entropy contribution. Site marker competitive binding experiments revealed that the binding site of TH was located in subdomain IIA (Sudlow site I) of HSA. Molecular docking study further substantiates that TH binds to the hydrophobic cavity of subdomain IIA (Sudlow site I) of HSA. Further, we have studied the cytotoxic activity of TH and TH-HSA complex on breast cancer cell lines (MCF-7) by MTT assay and LDH assay. These studies revealed that TH-HSA complex showed the higher level of cytotoxicity in cancer cells than TH dye-treated MCF-7 cells and the significant adverse effect did not found in the normal HBL-100 cells. Fluorescence microscopy analyses of nuclear fragmentation studies validate the significant reduction of viability of TH-HSA-treated human MCF-7 breast cancer cells through activation of apoptotic-mediated pathways.

  6. Interaction between ropinirole hydrochloride and aspirin with human serum albumin as binary and ternary systems by multi-spectroscopic, molecular modeling and zeta potential

    Energy Technology Data Exchange (ETDEWEB)

    Mahaki, Hanie, E-mail: hanieh.mahaki@gmail.com [Department of Biology, Faculty of Sciences, Mashhad Branch, Islamic Azad University, Mashhad (Iran, Islamic Republic of); Memarpoor-Yazdi, Mina; Chamani, Jamshidkhan [Department of Biology, Faculty of Sciences, Mashhad Branch, Islamic Azad University, Mashhad (Iran, Islamic Republic of); Reza Saberi, Mohammad [Medical Chemistry Department, School of Pharmacy, Mashhad University of Medical Sciences, Mashhad (Iran, Islamic Republic of)

    2013-02-15

    The aim of the present study was to describe the competition of ropinirole hydrochloride (RP) and aspirin (ASA) in binding to human serum albumin (HSA) in physiological buffer (pH=7.4) using multi-spectroscopic, molecular modeling and zeta-potential measurements. Fluorescence analysis was used to define the binding and quenching properties of drug-HSA complexes in binary and ternary systems. Fluorescence spectroscopy showed that in the presence of RP, the binding constant of HSA-ASA was increased. Static quenching was confirmed to result in the fluorescence quenching and FRET. The effect of drugs on the conformation of HSA was analyzed using synchronous fluorescence spectroscopy, three-dimensional fluorescence spectra and circular dichroism (CD). The RLS method determined the critical aggregation concentration of drugs on HSA in binary and ternary systems that confirmed the zeta potential results. Structural modeling showed that the affinity of each of the drugs to HSA in binary and ternary systems confirms the spectroscopic results. - Highlights: Black-Right-Pointing-Pointer We studied the interaction of ropinirole hydrochloride and aspirin with HSA. Black-Right-Pointing-Pointer Molecular modeling and zeta-potential used to describe competitive interaction. Black-Right-Pointing-Pointer We determined the critical induced aggregation concentration of both drugs on HSA. Black-Right-Pointing-Pointer The binding mechanism of drugs as separate and simultaneous to HSA has been compared. Black-Right-Pointing-Pointer The binding site of both drugs as simultaneous effects on HSA has been determined.

  7. Green synthesis of zero-valent Fe-nanoparticles: Catalytic degradation of rhodamine B, interactions with bovine serum albumin and their enhanced antimicrobial activities.

    Science.gov (United States)

    Khan, Zaheer; Al-Thabaiti, Shaeel Ahmad

    2018-03-01

    Biomimetic method was used for the synthesis of Fe-nanoparticles (FeNPs). FeCl 3 and Hibiscus sabdariffa, Roselle flower aqueous extract (HBS) were employed in the present studies. The FeNPs have been characterized by using UV-visible spectroscopy, transmission electron microscope (TEM), and energy dispersion X-ray spectroscopy (EDS). The average particles diameter was found to be 18 nm. The as prepared FeNPs were used as a catalyst to the oxidative degradation of rhodamine B (RB) in presence of NaBH 4 . The effects of various quencher on the degradation rates were examined by employing ammonium oxalate (AO), benzoquinone (BQ), isopropyl alcohol (IPA), and potassium iodide (KI). The interactions of FeNPs with bovine serum albumin (BSA) have been determined and discussed. Adsorption of FeNPs into the core of BSA changes the tryptophan environment from hydrophobic to hydrophilic (from folding to partially folded and/or unfolded). Tryptophan residues, indole moieties of BSA were responsible to complex formation with FeNPs in excited states via electrostatic, van der Waals, hydrogen bonding, hydrophobic and hydrophilic interactions with static quenching. The antimicrobial activities of FeNPs have been determined against human pathogens. Hibiscus sabdariffa flower extract shows mild antimicrobial activities against all target pathogenic organisms. FeNPs have potential antimicrobial activity against both bacterial strains and candida fungus even at low concentration, and retains potential application in biomedical industries. Copyright © 2018 Elsevier B.V. All rights reserved.

  8. Study of fluorescence interaction and conformational changes of bovine serum albumin with histamine H₁ -receptor--drug epinastine hydrochloride by spectroscopic and time-resolved fluorescence methods.

    Science.gov (United States)

    Ariga, Girish G; Naik, Praveen N; Nandibewoor, Sharanappa T; Chimatadar, Shivamurti A

    2015-11-01

    The fluorescence, ultraviolet (UV) absorption, time resolved techniques, circular dichroism (CD), and infrared spectral methods were explored as tools to investigate the interaction between histamine H1 drug, epinastine hydrochloride (EPN), and bovine serum albumin (BSA) under simulated physiological conditions. The experimental results showed that the quenching of the BSA by EPN was static quenching mechanism and also confirmed by lifetime measurements. The value of n close to unity indicated that one molecule of EPN was bound to protein molecule. The binding constants (K) at three different temperatures were calculated (7.1 × 10(4), 5.5 × 10(4), and 3.9 × 10(4) M(-1)). Based on the thermodynamic parameters (ΔH(0), ΔG(0), and ΔS(0)), the nature of binding forces operating between drug and protein was proposed. The site of binding of EPN in the protein was proposed to be Sudlow's site I based on displacement experiments using site markers viz, warfarin, ibuprofen, and digitoxin. Based on the Förster's theory of non-radiation energy transfer, the binding average distance, r between the donor (BSA) and acceptor (EPN) was evaluated and found to be 4.48 nm. The UV-visible, synchronous fluorescence, CD, and three-dimensional fluorescence spectral results revealed the changes in secondary structure of the protein upon its interaction with EPN. © 2015 Wiley Periodicals, Inc.

  9. Metal supplementation to UASB bioreactors: from cell-metal interactions to full-scale application

    International Nuclear Information System (INIS)

    Fermoso, Fernando G.; Bartacek, Jan; Jansen, Stefan; Lens, Piet N.L.

    2009-01-01

    Upflow anaerobic sludge bed (UASB) bioreactors are commonly used for anaerobic wastewater treatment. Trace metals need to be dosed to these bioreactors to maintain microbial metabolism and growth. The dosing needs to balance the supply of a minimum amount of micronutrients to support a desired microbial activity or growth rate with a maximum level of micronutrient supply above which the trace metals become inhibitory or toxic. In studies on granular sludge reactors, the required micronutrients are undefined and different metal formulations with differences in composition, concentration and species are used. Moreover, an appropriate quantification of the required nutrient dosing and suitable ranges during the entire operational period has been given little attention. This review summarizes the state-of-the-art knowledge of the interactions between trace metals and cells growing in anaerobic granules, which is the main type of biomass retention in anaerobic wastewater treatment reactors. The impact of trace metal limitation as well as overdosing (toxicity) on the biomass is overviewed and the consequences for reactor performance are detailed. Special attention is given to the influence of metal speciation in the liquid and solid phase on bioavailability. The currently used methods for trace metal dosing into wastewater treatment reactors are overviewed and ways of optimization are suggested.

  10. Metal supplementation to UASB bioreactors: from cell-metal interactions to full-scale application

    Energy Technology Data Exchange (ETDEWEB)

    Fermoso, Fernando G. [Sub-department of Environmental Technology, Wageningen University, ' Biotechnion' -Bomenweg 2, P.O. Box 8129, 6700 EV Wageningen (Netherlands); Bartacek, Jan [Sub-department of Environmental Technology, Wageningen University, ' Biotechnion' -Bomenweg 2, P.O. Box 8129, 6700 EV Wageningen (Netherlands); Pollution Prevention and Control core, UNESCO-IHE, P.O. Box 3015, 2601 DA Delft (Netherlands); Jansen, Stefan [Laboratory of Physical Chemistry and Colloid Science, Wageningen University, Dreijenplein 6, 6703 HB Wageningen (Netherlands); Lens, Piet N.L., E-mail: Piet.Lens@wur.nl [Sub-department of Environmental Technology, Wageningen University, ' Biotechnion' -Bomenweg 2, P.O. Box 8129, 6700 EV Wageningen (Netherlands); Pollution Prevention and Control core, UNESCO-IHE, P.O. Box 3015, 2601 DA Delft (Netherlands)

    2009-06-01

    Upflow anaerobic sludge bed (UASB) bioreactors are commonly used for anaerobic wastewater treatment. Trace metals need to be dosed to these bioreactors to maintain microbial metabolism and growth. The dosing needs to balance the supply of a minimum amount of micronutrients to support a desired microbial activity or growth rate with a maximum level of micronutrient supply above which the trace metals become inhibitory or toxic. In studies on granular sludge reactors, the required micronutrients are undefined and different metal formulations with differences in composition, concentration and species are used. Moreover, an appropriate quantification of the required nutrient dosing and suitable ranges during the entire operational period has been given little attention. This review summarizes the state-of-the-art knowledge of the interactions between trace metals and cells growing in anaerobic granules, which is the main type of biomass retention in anaerobic wastewater treatment reactors. The impact of trace metal limitation as well as overdosing (toxicity) on the biomass is overviewed and the consequences for reactor performance are detailed. Special attention is given to the influence of metal speciation in the liquid and solid phase on bioavailability. The currently used methods for trace metal dosing into wastewater treatment reactors are overviewed and ways of optimization are suggested.

  11. Fundamental Study on Laser Interaction with Metal Matrix Nanocomposites

    OpenAIRE

    Ma, Chao

    2015-01-01

    The objective of this study is to significantly advance the fundamental understanding of laser interaction with metal matrix nanocomposites (MMNCs) and to overcome the fundamental limits of current laser processing techniques by tuning heat transfer and fluid flow using nanoparticles.Ultrasonic assisted electrocodeposition was used to prepare MMNCs samples (e.g., Ni/Al2O3) for laser melting experiments. Microstructural study showed that uniform distribution and dispersion of nanoparticles wer...

  12. Electron emission during multicharged ion-metal surface interactions

    International Nuclear Information System (INIS)

    Zeijlmans van Emmichoven, P.A.; Havener, C.C.; Hughes, I.G.; Overbury, S.H.; Robinson, M.T.; Zehner, D.M.; Meyer, F.W.

    1992-01-01

    The electron emission during multicharged ion-metal surface interactions will be discussed. The interactions lead to the emission of a significant number of electrons. Most of these electrons have energies below 30 eV. For incident ions with innershell vacancies the emission of Auger electrons that fill these vacancies has been found to occur mainly below the surface. We will present recently measured electron energy distributions which will be used to discuss the mechanisms that lead to the emission of Auger and of low-energy electrons

  13. Interaction of high-intensity laser radiation with metals.

    Science.gov (United States)

    Linlor, W. I.

    1971-01-01

    The interaction is characterized by the production of plasma, within which the primary absorption occurs. Absorption of laser radiation by a plasma may occur by several processes. The absorption process called 'inverse bremsstrahlung' is discussed. The interaction of a laser beam with the plasma produced from a thick metal target was studied. The results of the measurements of the ion kinetic energies are presented in a graph. In addition to measurements with thick targets, information was also obtained with a thin foil of gold.

  14. Copper transfer from Cu-Aβ to human serum albumin inhibits aggregation, radical production and reduces Aβ toxicity

    DEFF Research Database (Denmark)

    Perrone, Lorena; Mothes, Emmanuelle; Vignes, Maeva

    2010-01-01

    Amyloid-β peptides (Aβ) and the protein human serum albumin (HSA) interact in vivo. They are both localised in the blood plasma and in the cerebrospinal fluid. Among other functions, HSA is involved in the transport of the essential metal copper. Complexes between Aβ and copper ions have been...

  15. Interactions of bovine serum albumin with cationic imidazolium and quaternary ammonium gemini surfactants: effects of surfactant architecture.

    Science.gov (United States)

    Zhou, Ting; Ao, Mingqi; Xu, Guiying; Liu, Teng; Zhang, Juan

    2013-01-01

    The interactions of BSA with a series of cationic imidazolium gemini surfactants ([C(n)-s-C(n)im]Br(2), n=10, 12, 14, s=2, 4, 6), quaternary ammonium surfactants (C(12)C(2)C(12)), and their corresponding monomers ([C(12)mim]Br and DTAB) are investigated by fluorescence using pyrene as a molecular probe, synchronous fluorescence, circular dichroism (CD), and UV-visible absorption spectra. These surfactants are used to elucidate the effects of surfactant hydrophilic head group, spacer length, and hydrophobic chain length on the conformation of BSA. The results of fluorescence spectra and CD show that the imidazolium gemini surfactants with shorter spacers or with longer hydrophobic chains have a larger effect on BSA unfolding, and the imidazolium gemini surfactant interacts with BSA more strongly than its corresponding monomer and the quaternary ammonium gemini surfactant. These conclusions have been confirmed by the binding constants (K(a)) and binding sites (n) for the BSA/surfactant system. Stern-Volmer quenching constants K(SV) of cationic surfactants binding to BSA are obtained, indicating that the probable quenching mechanism is initiated by ground-state complex formation rather than by dynamic collision. Moreover, the synchronous fluorescence spectra show that the surfactants mainly interact with tryptophan residues of BSA. Copyright © 2012 Elsevier Inc. All rights reserved.

  16. Negligible interaction of [Ru(Phen)3]2+with human serum albumin makes it promising for a reliable invivo assessment of the tissue oxygenation.

    Science.gov (United States)

    Belej, Dominik; Jurasekova, Zuzana; Nemergut, Michal; Wagnieres, Georges; Jancura, Daniel; Huntosova, Veronika

    2017-09-01

    The interaction between a ruthenium - based water soluble oxygen probe ([Ru(Phen) 3 ] 2+ , phen - phenanthroline) and human serum albumin (HSA) was investigated with the aim of describing the influence of HSA on the [Ru(Phen) 3 ] 2+ luminescence properties. Nowadays, several oxygen sensitive luminescent probes are used to determine the oxygen level in different compartments of living organisms. However, they can interact, depending on their hydrophilic/hydrophobic characters, with various serum proteins, and/or lipids, during their utilization for invivo oxygen measurement. Since HSA is the most abundant serum protein in most biological organisms, its presence may affect the spectral properties of the employed probes and, consequently, the determination of the oxygen concentration. Having this in mind, we have applied several spectroscopic and calorimetric techniques to study [Ru(Phen) 3 ] 2+ - HSA mixtures. Only a negligible effect of HSA on the absorption and luminescence spectra of [Ru(Phen) 3 ] 2+ was observed. In addition, differential scanning calorimetric studies showed that [Ru(Phen) 3 ] 2+ does not significantly influence HSA thermal stability. Importantly, [Ru(Phen) 3 ] 2+ retained a reliable luminescence lifetime sensitivity to the oxygen concentration in solutions supplemented with HSA and in U87 MG cancer cells. Finally, the biodistribution of [Ru(Phen) 3 ] 2+ in the presence of serum proteins in the blood stream of chick embryo's chorioallantoic membrane (CAM) was investigated. Fast [Ru(Phen) 3 ] 2+ and similar extravasations were observed in the presence or absence of CAM-serum. We can conclude that HSA-[Ru(Phen) 3 ] 2+ complex interaction does not significantly influence the potential of [Ru(Phen) 3 ] 2+ to be a suitable candidate for a reliable oxygen probe in living organisms. Copyright © 2017 Elsevier Inc. All rights reserved.

  17. Spectroscopic analyses on interaction of Amantadine-Salicylaldehyde, Amantadine-5-Chloro-Salicylaldehyde and Amantadine-o-Vanillin Schiff-Bases with bovine serum albumin (BSA)

    Science.gov (United States)

    Wang, Zhiqiu; Gao, Jingqun; Wang, Jun; Jin, Xudong; Zou, Mingming; Li, Kai; Kang, Pingli

    2011-12-01

    In this work, three Tricyclo [3.3.1.1(3,7)] decane-1-amine (Amantadine) Schiff-Bases, Amantadine-Salicylaldehyde (AS), Amantadine-5-Chloro-Salicylaldehyde (AS-5-C) and Amantadine-o-Vanillin (AS-o-V), were synthesized by direct heating reflux method in ethanol solution and characterized by infrared spectrum and elementary analysis. Fluorescence quenching was used to study the interaction of these Amantadine Schiff-Bases (AS, AS-5-C and AS-o-V) with bovine serum albumin (BSA). According to fluorescence quenching calculations the bimolecular quenching constant ( Kq), apparent quenching constant ( KSV), effective binding constant ( KA) and corresponding dissociation constant ( KD), binding site number ( n) and binding distance ( r) were obtained. The results show that these Amantadine Schiff-Bases can obviously bind to BSA molecules and the binding strength order is AS < AS-5-C = AS-o-V. Synchronous fluorescence spectroscopy reveals that these Amantadine Schiff-Bases adopt different way to bind with BSA molecules. That is, the AS and AS-5-C are accessibility to tryptophan (Trp) residues more than the tyrosine (Tyr) residues, while the AS-o-V is equally close to the Tyr and Trp residues.

  18. Zinc Phthalocyanine Labelled Polyethylene Glycol: Preparation, Characterization, Interaction with Bovine Serum Albumin and Near Infrared Fluorescence Imaging in Vivo

    Directory of Open Access Journals (Sweden)

    Tianjun Liu

    2012-05-01

    Full Text Available Zinc phthalocyanine labelled polyethylene glycol was prepared to track and monitor the in vivo fate of polyethylene glycol. The chemical structures were characterized by nuclear magnetic resonance and infrared spectroscopy. Their light stability and fluorescence quantum yield were evaluated by UV-Visible and fluorescence spectroscopy methods. The interaction of zinc phthalocyanine labelled polyethylene glycol with bovine serum albumin was evaluated by fluorescence titration and isothermal titration calorimetry methods. Optical imaging in vivo, organ aggregation as well as distribution of fluorescence experiments for tracking polyethylene glycol were performed with zinc phthalocyanine labelled polyethylene glycol as fluorescent agent. Results show that zinc phthalocyanine labelled polyethylene glycol has good optical stability and high emission ability in the near infrared region. Imaging results demonstrate that zinc phthalocyanine labelled polyethylene glycol can track and monitor the in vivo process by near infrared fluorescence imaging, which implies its potential in biomaterials evaluation in vivo by a real-time noninvasive method.

  19. Multi-spectroscopic and molecular modeling approaches to elucidate the binding interaction between bovine serum albumin and darunavir, a HIV protease inhibitor

    Science.gov (United States)

    Shi, Jie-Hua; Zhou, Kai-Li; Lou, Yan-Yue; Pan, Dong-Qi

    2018-01-01

    Darunavir (DRV), a second-generation HIV protease inhibitor, is widely used across the world as an important component of HIV therapy. The interaction of DRV with bovine serum albumin (BSA), a major carrier protein, has been studied under simulated physiological conditions (pH 7.4) by multi-spectroscopic techniques in combination with molecular modeling. Fluorescence data revealed that the intrinsic fluorescence of BSA was quenched by DRV in terms of a static quenching procedure due to the formation of the DRV-BSA complex. The results indicated the presence of single weak affinity binding site ( 103 M- 1, 310 K) on protein. The thermodynamic parameters, namely enthalpy change (ΔH0), entropy change (ΔS0) and Gibbs free energy change (ΔG0) were calculated, which signified that the binding reaction was spontaneous, the main binding forces were hydrogen bonding and van der Waals forces. Importantly, competitive binding experiments with three site probes, phenylbutazone (in sub-domain IIA, site I), ibuprofen (in sub-domain IIIA, site II) and artemether (in the interface between sub-domain IIA and IIB, site II'), suggested that DRV was preferentially bound to the hydrophobic cavity in site II' of BSA, and this finding was validated by the docking results. Additionally, synchronous fluorescence, three-dimensional fluorescence and Resonance Rayleigh Scattering (RRS) spectroscopy gave qualitative information on the conformational changes of BSA upon adding DRV, while quantitative data were obtained with Fourier transform infrared spectroscopy (FT-IR).

  20. Application of capillary electrophoresis-frontal analysis for comparative evaluation of the binding interaction of captopril with human serum albumin in the absence and presence of hydrochlorothiazide.

    Science.gov (United States)

    Liu, Ting-Ting; Xiang, Li-Li; Wang, Jian-Ling; Chen, Dong-Ying

    2015-11-10

    The application of capillary electrophoresis-frontal analysis for comparative evaluation of the binding interaction between antihypertensive drug captopril and human serum albumin in the absence and presence of diuretic drug hydrochlorothiazide was presented in this work. At near-physiological conditions (67mM phosphate buffer, pH 7.4, I=0.17, 37°C), the individual solution of 100μM captopril and the co-binding solution with 60μM hydrochlorothiazide added were pre-equilibrated with series concentrations of HSA (10-475μM) respectively, introducing hydrodynamically into an uncoated fused silica capillary (35cm×50μm I.D. with 26.5cm effective length). The values of number of binding sites, the binding constant for captopril and hydrochlorothiazide binding to HSA were obtained, respectively. It can be found that both drugs exhibit moderate binding properties towards HSA and there does not exist significant competitive binding effects between them. Copyright © 2015 Elsevier B.V. All rights reserved.

  1. Interaction of bovine serum albumin (BSA) with novel gemini surfactants studied by synchrotron radiation scattering (SR-SAXS), circular dichroism (CD), and nuclear magnetic resonance (NMR).

    Science.gov (United States)

    Gospodarczyk, W; Szutkowski, K; Kozak, M

    2014-07-24

    The interaction of three dicationic (gemini) surfactants-3,3'-[1,6-(2,5-dioxahexane)]bis(1-dodecylimidazolium) chloride (oxyC2), 3,3'-[1,16-(2,15-dioxahexadecane)]bis(1-dodecylimidazolium) chloride (oxyC12), and 1,4-bis(butane)imidazole-1-yl-3-dodecylimidazolium chloride (C4)--with bovine serum albumin (BSA) has been studied by the use of small-angle X-ray scattering (SAXS), circular dichroism (CD), and (1)H nuclear magnetic resonance diffusometry. The results of CD studies show that the conformation of BSA was changed dramatically in the presence of all studied surfactants. The greater decrease (from 56 to 24%) in the α-helical structure of BSA was observed for oxyC2 surfactant. The radii of gyration estimated from SAXS data varied between 3 and 26 nm for the BSA/oxyC2 and BSA/oxyC12 systems. The hydrodynamic radius of the BSA/surfactant system estimated from NMR diffusometry varies between 5 and 11 nm for BSA/oxyC2 and 5 and 8 nm for BSA/oxyC12.

  2. New copper(I) complexes bearing lomefloxacin motif: Spectroscopic properties, in vitro cytotoxicity and interactions with DNA and human serum albumin.

    Science.gov (United States)

    Komarnicka, Urszula K; Starosta, Radosław; Kyzioł, Agnieszka; Płotek, Michał; Puchalska, Małgorzata; Jeżowska-Bojczuk, Małgorzata

    2016-12-01

    In this paper we present lomefloxacin's (HLm, 2nd generation fluoroquinolone antibiotic agent) organic and inorganic derivatives: aminomethyl(diphenyl)phosphine (PLm), its oxide as well as new copper(I) iodide or copper(I) thiocyanate complexes with PLm and 2,9-dimethyl-1,10-phenanthroline (dmp) or 2,2'-biquinoline (bq) as the auxiliary ligands. The synthesized compounds were fully characterised by NMR, UV-Vis and luminescence spectroscopies. Selected structures were analysed by theoretical DFT (density functional theory) methods. High stability of the complexes in aqueous solutions in the presence of atmosferic oxygen was proven. Cytotoxic activity of all compounds was tested towards three cancer cell lines (CT26 - mouse colon carcinoma, A549 - human lung adenocarcinoma, and MCF7 - human breast adenocarcinoma). All complexes are characterised by cytotoxic activity higher than the activity of the parent drug and its organic derivatives as well as cisplatin. Studied derivatives as well as parent drug do not intercalate to DNA, except Cu(I) complexes with bq ligand. All studied complexes caused single-stranded cleavage of the sugar-phosphate backbone of plasmid DNA. The addition of H 2 O 2 caused distinct changes in the plasmid structure and led to single- and/or double-strain plasmid cleavage. Studied compounds interact with human serum albumin without affecting its secondary structure. Copyright © 2016 Elsevier Inc. All rights reserved.

  3. Oxygen Switching of the Epitaxial Graphene-Metal Interaction

    DEFF Research Database (Denmark)

    Larciprete, Rosanna; Ulstrup, Søren; Lacovig, Paolo

    2012-01-01

    in the valence band are removed, and the spectrum of strongly hole-doped, quasi free-standing graphene with a single Dirac cone around the K point is observed. The oxygen can be deintercalated by annealing, and this process takes place at around T = 600 K, in a rather abrupt way. A small amount of carbon atoms......Using photoemission spectroscopy techniques, we show that oxygen intercalation is achieved on an extended layer of epitaxial graphene on Ir(111), which results in the “lifting” of the graphene layer and in its decoupling from the metal substrate. The oxygen adsorption below graphene proceeds...... as on clean Ir(111), giving only a slightly higher oxygen coverage. Upon lifting, the C 1s signal shows a downshift in binding energy, due to the charge transfer to graphene from the oxygen-covered metal surface. Moreover, the characteristic spectral signatures of the graphenesubstrate interaction...

  4. A numerical analysis of molten metal drop and coolant interaction

    International Nuclear Information System (INIS)

    Cao, X.; Hajima, Ryoichi; Furuta, Kazuo; Kondo, Shunsuke

    2000-01-01

    The interaction of molten metal drop and coolant is numerically analyzed to investigate the mechanism of fragmentation in vapor explosion. The numerical study is carried out by using a developed simulation code based on multi-phase thermal hydraulic model, which includes physical phenomena required for the analysis: heat transfer, mass change, liquid evaporation and treatment of surface. Several computational techniques are also implemented to improve the efficiency and stability of the numerical scheme. The obtained numerical results show that the growth of spikes on the molten metal drop surface is similar to that observed in Ciccarelli's experiment. The numerical study suggests that quick growth of spikes is the essential mechanism of fragmentation, which is caused by Taylor instability. (author)

  5. Transition-metal interactions in aluminum-rich intermetallics

    International Nuclear Information System (INIS)

    Al-Lehyani, Ibrahim; Widom, Mike; Wang, Yang; Moghadam, Nassrin; Stocks, G. Malcolm; Moriarty, John A.

    2001-01-01

    The extension of the first-principles generalized pseudopotential theory (GPT) to transition-metal (TM) aluminides produces pair and many-body interactions that allow efficient calculations of total energies. In aluminum-rich systems treated at the pair-potential level, one practical limitation is a transition-metal overbinding that creates an unrealistic TM-TM attraction at short separations in the absence of balancing many-body contributions. Even with this limitation, the GPT pair potentials have been used effectively in total-energy calculations for Al-TM systems with TM atoms at separations greater than 4 Aa. An additional potential term may be added for systems with shorter TM atom separations, formally folding repulsive contributions of the three- and higher-body interactions into the pair potentials, resulting in structure-dependent TM-TM potentials. Towards this end, we have performed numerical ab initio total-energy calculations using the Vienna ab initio simulation package for an Al-Co-Ni compound in a particular quasicrystalline approximant structure. The results allow us to fit a short-ranged, many-body correction of the form a(r 0 /r) b to the GPT pair potentials for Co-Co, Co-Ni, and Ni-Ni interactions

  6. Role of hydrogen-bonding and photoinduced electron transfer (PET) on the interaction of resorcinol based acridinedione dyes with Bovine Serum Albumin (BSA) in water

    Energy Technology Data Exchange (ETDEWEB)

    Kumaran, Rajendran, E-mail: kumaranwau@rediffmail.com [Department of Chemistry, Dwaraka Doss Goverdhan Doss, Vaishnav College (Autonomous), 833, Gokul Bagh, E.V.R. Periyar Road, Arumbakkam, Chennai 600106, Tamil Nadu (India); Vanjinathan, Mahalingam [Department of Chemistry, Dwaraka Doss Goverdhan Doss, Vaishnav College (Autonomous), 833, Gokul Bagh, E.V.R. Periyar Road, Arumbakkam, Chennai 600106, Tamil Nadu (India); Ramamurthy, Perumal [National Centre for Ultrafast Processes, University of Madras, Taramani Campus Chennai 600113, Tamil Nadu (India)

    2015-08-15

    Resorcinol based acridinedione (ADDR) dyes are a class of laser dyes and have structural similarity with purine derivatives, nicotinamide adenine dinucleotide (NADH) analogs. These dyes are classified into photoinduced electron transfer (PET) and non-photoinduced electron transfer dyes, and the photophysical properties of family of these dyes exhibiting PET behavior are entirely different from that of non-PET dyes. The PET process in ADDR dyes is governed by the solvent polarity such that an ADDR dye exhibits PET process through space in an aprotic solvent like acetonitrile and does not exhibit the same in protic solvents like water and methanol. A comparison on the fluorescence emission, lifetime and nature of interaction of various ADDR dyes with a large globular protein like Bovine Serum Albumin (BSA) was carried out in aqueous solution. The interaction of PET based ADDR dyes with BSA in water is found to be largely hydrophobic, but hydrogen-bonding interaction of BSA with dye molecule influences the fluorescence emission of the dye and shifts the emission towards red region. Fluorescence spectral studies reveal that the excited state properties of PET based ADDR dyes are largely influenced by the addition of BSA. The microenvironment around the dye results in significant change in the fluorescence lifetime and emission. Fluorescence enhancement with a red shift in the emission results after the addition of BSA to ADDR dyes containing free amino hydrogen in the 10th position of basic acridinedione dye. The amino hydrogen (N–H) in the 10th position of ADDR dye is replaced by methyl group (N–CH{sub 3}), a significant decrease in the fluorescence intensity with no apparent shift in the emission maximum was observed after the addition of BSA. The nature of interaction between ADDR dyes with BSA is hydrogen-bonding and the dye remains unbound even at the highest concentration of BSA. Circular Dichroism (CD) studies show that the addition of dye to BSA results in

  7. Role of hydrogen-bonding and photoinduced electron transfer (PET) on the interaction of resorcinol based acridinedione dyes with Bovine Serum Albumin (BSA) in water

    International Nuclear Information System (INIS)

    Kumaran, Rajendran; Vanjinathan, Mahalingam; Ramamurthy, Perumal

    2015-01-01

    Resorcinol based acridinedione (ADDR) dyes are a class of laser dyes and have structural similarity with purine derivatives, nicotinamide adenine dinucleotide (NADH) analogs. These dyes are classified into photoinduced electron transfer (PET) and non-photoinduced electron transfer dyes, and the photophysical properties of family of these dyes exhibiting PET behavior are entirely different from that of non-PET dyes. The PET process in ADDR dyes is governed by the solvent polarity such that an ADDR dye exhibits PET process through space in an aprotic solvent like acetonitrile and does not exhibit the same in protic solvents like water and methanol. A comparison on the fluorescence emission, lifetime and nature of interaction of various ADDR dyes with a large globular protein like Bovine Serum Albumin (BSA) was carried out in aqueous solution. The interaction of PET based ADDR dyes with BSA in water is found to be largely hydrophobic, but hydrogen-bonding interaction of BSA with dye molecule influences the fluorescence emission of the dye and shifts the emission towards red region. Fluorescence spectral studies reveal that the excited state properties of PET based ADDR dyes are largely influenced by the addition of BSA. The microenvironment around the dye results in significant change in the fluorescence lifetime and emission. Fluorescence enhancement with a red shift in the emission results after the addition of BSA to ADDR dyes containing free amino hydrogen in the 10th position of basic acridinedione dye. The amino hydrogen (N–H) in the 10th position of ADDR dye is replaced by methyl group (N–CH 3 ), a significant decrease in the fluorescence intensity with no apparent shift in the emission maximum was observed after the addition of BSA. The nature of interaction between ADDR dyes with BSA is hydrogen-bonding and the dye remains unbound even at the highest concentration of BSA. Circular Dichroism (CD) studies show that the addition of dye to BSA results in a

  8. Static and dynamic interaction of a naturally occurring photochromic molecule with bovine serum albumin studied by UV-visible absorption and fluorescence spectroscopy.

    Science.gov (United States)

    Gentili, Pier Luigi; Ortica, Fausto; Favaro, Gianna

    2008-12-25

    In this work, the interaction of a naturally occurring chromene, flindersine (FL), and bovine serum albumin (BSA) has been investigated by UV-vis absorption and fluorescence spectroscopy, time-resolved lifetime measurements, steady state photochemistry, and semiempirical calculations. The interplay of FL with tryptophan (Trp) has been studied in parallel. The interaction of FL with BSA causes fluorescence quenching of BSA through both static and dynamic quenching mechanisms. FL binds BSA with a stoichiometry that varies from 1.09:1 to 0.80:1 as the temperature increases from 293 to 308 K. The reaction is characterized by negative enthalpy (deltaH degrees = -193 kJ mol(-1)) and negative entropy (deltaS degrees = -550 J K(-1) mol(-1)), indicating that the predominant forces in the FL-BSA complex are hydrogen bonding and van der Waals forces. The binding distance between the protein and the photochrome was calculated as 2.5 nm, according to the Foerster theory on resonance energy transfer. The effect of FL concentration on the BSA fluorescence was analyzed according to the maximum entropy method. FL also quenches the emission of Trp with a mechanism that, based on the experimental evidence, excludes both static and dynamic effects. An alternative relaxation pathway, consisting in an electron transfer from a prefluorescent state of Trp to FL, is put forward. The photobehavior of FL is affected by the interplay with BSA but not with Trp. When FL is complexed with BSA, it becomes a more fluorescent and more reactive species. Semiempirical calculations of the lowest optically active electronic transitions of hypothetical FL photoproducts suggest the most likely structure for the photoproduct.

  9. Biophysical and In Silico Studies of the Interaction between the Anti-Viral Agents Acyclovir and Penciclovir, and Human Serum Albumin.

    Science.gov (United States)

    Abdelhameed, Ali S; Bakheit, Ahmed H; Almutairi, Fahad M; AlRabiah, Haitham; Kadi, Adnan A

    2017-11-05

    Acyclovir (ACV) and penciclovir (PNV) have been commonly used during the last few decades as potent antiviral agents, especially for the treatment of herpes virus infections. In the present research their binding properties with human serum albumin (HSA) were studied using different advanced spectroscopic and in-silico methods. The interactions between ACV/PNV and HSA at the three investigated temperatures revealed a static type of binding. Extraction of the thermodynamic parameters of the ACV-HSA and PNV-HSA systems from the measured spectrofluorimetric data demonstrated spontaneous interactions with an enthalpy change (∆ H ⁰) of -1.79 ± 0.29 and -4.47 ± 0.51 kJ·mol -1 for ACV and PNV, respectively. The entropy change (∆ S ⁰) of 79.40 ± 0.95 and 69.95 ± 1.69 J·mol -1 ·K -1 for ACV and PNV, respectively, hence supported a potential contribution of electrostatic binding forces to the ACV-HSA and PNV-HSA systems. Putative binding of ACV/PNV to HSA, using previously reported site markers, showed that ACV/PNV were bound to HSA within subdomains IIA and IIIA (Sudlow sites I and II). Further confirmation was obtained through molecular docking studies of ACV-HSA and PNV-HSA binding, which confirmed the binding site of ACV/PNV with the most stable configurations of ACV/PNV within the HSA. These ACV/PNV conformers were shown to have free energies of -25.61 and -22.01 kJ·mol -1 for ACV within the HSA sites I and II and -22.97 and -26.53 kJ·mol -1 for PNV in HSA sites I and II, with hydrogen bonding and electrostatic forces being the main binding forces in such conformers.

  10. Studies on the interactions of chloroquine diphosphate and phenelzine sulfate drugs with human serum albumin and human hemoglobin proteins by spectroscopic techniques

    Energy Technology Data Exchange (ETDEWEB)

    Tunç, Sibel, E-mail: stunc@akdeniz.edu.tr; Duman, Osman, E-mail: osmanduman@akdeniz.edu.tr; Bozoğlan, Bahar Kancı

    2013-08-15

    The interactions of chloroquine diphosphate (CQP) and phenelzine sulfate (PS) drugs with human serum albumin (HSA) and human hemoglobin (HMG) proteins were investigated by various spectroscopic methods. It was found that CQP caused the fluorescence quenching of protein molecules through a static quenching mechanism, but PS did not. The values of Stern–Volmer quenching constant, bimolecular quenching constant, binding constant and number of binding site on the protein molecules were calculated for HSA–CQP and HMG–CQP systems at pH 7.4 and different temperatures. For CQP, there was only one binding site on HSA and HMG proteins and the binding affinity of HSA was higher than that of HMG. The binding constants decreased with increasing temperature. The values of negative enthalpy change and positive entropy change indicated that electrostatic interactions play an important role in the binding processes. In addition, the binding processes were spontaneous and carried out by exothermic reactions. According to Förster resonance energy transfer theory, the average binding distance between proteins and CQP was calculated as 3.72 nm for HSA–CQP system and 3.45 nm for HMG–CQP system. Circular dichroism analysis displayed that the addition of CQP led to a decrease in the α-helix amount of HSA and HMG proteins. -- Highlights: • Unlike PS, CQP was bounded by HSA and HMG proteins. • The fluorescence spectra of HSA and HMG were quenched by CQP through static mechanism. • HSA–CQP and HMG–CQP complexes were stabilized by electrostatic attraction forces. • Binding constants, thermodynamic parameters and binding distances were calculated. • The binding of CQP changed the conformational structure of HSA and HMG proteins.

  11. Spectroscopic interaction study of human serum albumin and human hemoglobin with Mersilea quadrifolia leaves extract mediated silver nanoparticles having antibacterial and anticancer activity

    Science.gov (United States)

    Maji, Anukul; Beg, Maidul; Mandal, Amit Kumar; Das, Somnath; Jha, Pradeep K.; Kumar, Anoop; Sarwar, Shamila; Hossain, Maidul; Chakrabarti, Pinak

    2017-08-01

    This study looks into a safe, proficient and low-cost way for the preparation of novel silver nanoparticles by using 5% aqueous leaves extract of a medicinal plant, Marsilea quadrifolia (family: Marsileaceae) without using any external reducing and stabilizing agents. The synthesized AgNPs showed maximum UV-Vis absorbance at 435 nm due to surface plasmon resonance (SPR). The average diameter (∼22.5 nm) of AgNPs was measured from TEM analysis and was also supported by FE-SEM. The existence of a silver signal in EDX spectra supported the AgNPs formation and negative zeta potential value (-18.7 mV) which suggested its stability. FT-IR spectroscopic analysis showed that the functional groups like sbnd Osbnd H, sbnd Nsbnd H and sbnd Cdbnd O were responsible for the synthesis of AgNPs. The antibacterial activity of the AgNPs was tested against E. coli ATCC 25922. The anticancer potential of AgNPs was also assessed using two different cell lines, such as MCF-7 and HeLa. The interaction study of AgNPs with human serum albumin (HSA) and human hemoglobin (Hb) was performed by means of UV-Vis, fluorescence spectroscopy, Circular dichroism (CD) and zeta potential measurement. More negative zeta potential values of AgNPs-HSA/Hb (-21.1/-19.5 mV) complexes than AgNPs (-18.7 mV) indicated corresponding stability of bio-conjugates. The basic structure of HSA/Hb remained unchanged and its secondary structure was slightly changed upon interaction with the AgNPs concluded from Circular dichroism. So, it can be predicted that this AgNPs may be applied in the medical field.

  12. Study on the interaction of phthalate esters to human serum albumin by steady-state and time-resolved fluorescence and circular dichroism spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Xie, Xiaoyun [National Key Laboratory of Organic Chemistry, Lanzhou University, Lanzhou 730000 (China); College of Earth and Environmental Sciences, Lanzhou University, Lanzhou 730000 (China); Wang, Zhaowei [College of Earth and Environmental Sciences, Lanzhou University, Lanzhou 730000 (China); Zhou, Ximin; Wang, Xiaoru [National Key Laboratory of Organic Chemistry, Lanzhou University, Lanzhou 730000 (China); Chen, Xingguo, E-mail: chenxg@lzu.edu.cn [National Key Laboratory of Organic Chemistry, Lanzhou University, Lanzhou 730000 (China); Department of Chemistry, Lanzhou University, Lanzhou 730000 (China)

    2011-09-15

    Highlights: {center_dot} Molecular docking revealed PAEs to be located in the hydrophobic pocket of HSA. {center_dot} HSA-DMP had one class of binding sites while HSA-BBP and HSA-DEHP had two types. {center_dot} Hydrophobic and hydrogen interactions dominated in the association of HSA-PAEs. {center_dot} The lifetime of Trp residue of HSA decreased after the addition of PAEs. {center_dot} The presences of PAEs could alter the second structure of HSA. - Abstract: Phthalate esters (PAEs) are globally pervasive contaminants that are considered to be endocrine disruptor chemicals and toxic environmental priority pollutants. In this paper, the interactions between PAEs and human serum albumin (HSA) were examined by molecular modelling, steady state and time-resolved fluorescence, ultraviolet-visible spectroscopy (UV-vis) and circular dichroism spectroscopy (CD). The association constants between PAEs and HSA were determined using the Stern-Volmer and Scatchard equations. The binding of dimethyl phthalate (DMP) to HSA has a single class of binding site and its binding constants (K) are 4.08 x 10{sup 3}, 3.97 x 10{sup 3}, 3.45 x 10{sup 3}, and 3.20 x 10{sup 3} L mol{sup -1} at 289, 296, 303, and 310 K, respectively. The Stern-Volmer and Scatchard plots both had two regression curves for HSA-butylbenzyl phthalate (BBP) and HSA-di-2-ethylhexyl phthalate (DEHP), which indicated that these bindings were via two types of binding sites: the numbers of binding site for the first type were lower than for the second type. The binding constants of the first type binding site were higher than those of the second type binding site at corresponding temperatures, the results suggesting that the first type of binding site had high affinity and the second binding site involved other sites with lower binding affinity and selectivity. The thermodynamic parameters of the binding reactions ({Delta}G{sup o}, {Delta}H{sup o} and {Delta}S{sup o}) were measured, and they indicated the presences

  13. Analysis of multi-site drug-protein interactions by high-performance affinity chromatography: Binding by glimepiride to normal or glycated human serum albumin.

    Science.gov (United States)

    Matsuda, Ryan; Li, Zhao; Zheng, Xiwei; Hage, David S

    2015-08-21

    High-performance affinity chromatography (HPAC) was used in a variety of formats to examine multi-site interactions between glimepiride, a third-generation sulfonylurea drug, and normal or in vitro glycated forms of the transport protein human serum albumin (HSA). Frontal analysis revealed that glimepiride interacts with normal HSA and glycated HSA at a group of high affinity sites (association equilibrium constant, or Ka, 9.2-11.8×10(5)M(-1) at pH 7.4 and 37°C) and a group of lower affinity regions (Ka, 5.9-16×10(3)M(-1)). Zonal elution competition studies were designed and carried out in both normal- and reversed-role formats to investigate the binding by this drug at specific sites. These experiments indicated that glimepiride was interacting at both Sudlow sites I and II. Allosteric effects were also noted with R-warfarin at Sudlow site I and with tamoxifen at the tamoxifen site on HSA. The binding at Sudlow site I had a 2.1- to 2.3-fold increase in affinity in going from normal HSA to the glycated samples of HSA. There was no significant change in the affinity for glimepiride at Sudlow site II in going from normal HSA to a moderately glycated sample of HSA, but a slight decrease in affinity was seen in going to a more highly glycated HSA sample. These results demonstrated how various HPAC-based methods can be used to profile and characterize multi-site binding by a drug such as glimepiride to a protein and its modified forms. The information obtained from this study should be useful in providing a better understanding of how drug-protein binding may be affected by glycation and of how separation and analysis methods based on HPAC can be employed to study systems with complex interactions or that involve modified proteins. Copyright © 2015 Elsevier B.V. All rights reserved.

  14. Quantum Butterfly Effect in Weakly Interacting Diffusive Metals

    Directory of Open Access Journals (Sweden)

    Aavishkar A. Patel

    2017-09-01

    Full Text Available We study scrambling, an avatar of chaos, in a weakly interacting metal in the presence of random potential disorder. It is well known that charge and heat spread via diffusion in such an interacting disordered metal. In contrast, we show within perturbation theory that chaos spreads in a ballistic fashion. The squared anticommutator of the electron-field operators inherits a light-cone-like growth, arising from an interplay of a growth (Lyapunov exponent that scales as the inelastic electron scattering rate and a diffusive piece due to the presence of disorder. In two spatial dimensions, the Lyapunov exponent is universally related at weak coupling to the sheet resistivity. We are able to define an effective temperature-dependent butterfly velocity, a speed limit for the propagation of quantum information that is much slower than microscopic velocities such as the Fermi velocity and that is qualitatively similar to that of a quantum critical system with a dynamical critical exponent z>1.

  15. Green synthesis, biological and spectroscopic study on the interaction of multi-component Mannich bases of imidazo[2,1-b]benzothiazoles with human serum albumin.

    Science.gov (United States)

    Maddili, Swetha K; Yandrati, Leela Prasad; Siddam, Shakuntala; Kannekanti, Vijaya Kumar; Gandham, Himabindu

    2017-11-01

    A series of Mannich bases of imidazo[2, l-b]benzothiazoles were prepared through one-pot multi-component reaction in the presence of water as an eco-friendly solvent. All the synthesized compounds were confirmed from IR, 1 HNMR, 13 CNMR, and Mass spectroscopy. Evaluation of in vitro anti-inflammatory and anti-microbial activities of all the synthesized derivatives was further accomplished. These results clearly displayed that compound 6d exhibited outstanding anti-inflammatory activity with a percentage inhibition of 70.23% by membrane stabilization method whereas 67.54% at 100μgmL -1 by the albumin denaturation method, which is comparable to the standard Diclofenac. Further screening against five fungal species (C. albicans ATCC 76615, C. mycoderma, C. utilis, A. flavus, and B. yeast) along with four gram positive (Methicillin-resistant S. aureus N315 (MRSA), Staphylococcus aureus ATCC 6538, Bacillus subtilis ATCC 21216, and Micrococcus luteus ATCC 4698), and six Gram-negative bacterial strains (Escherichia coli DH52, Escherichia coli JM109, Salmonella dysenteriae, Pseudomonas aeruginosa ATCC 27853, Bacillus proteus ATCC13315 and Bacillus typhi) was carried out. These findings manifested that compound 7c displayed excellent antifungal efficacy while compound 7b revealed significant anti-microbial activity. In addition binding behaviour of compound 7b was investigated by binding study between calf thymus DNA and compound 7b by UV-Vis absorption spectroscopy and further research about HSA interactions was carried out. Copyright © 2017 Elsevier B.V. All rights reserved.

  16. Detection of carrier heterogeneity by rate of ligand dialysis: medium-chain fatty acid interaction with human serum albumin and competition with chloride

    DEFF Research Database (Denmark)

    Honoré, B; Brodersen, R

    1988-01-01

    Binding equilibria for decanoate, octanoate, and hexanoate to defatted human serum albumin were investigated by dialysis exchange rate determinations in 66 mM sodium phosphate buffer, pH 7.4, 37 degrees C. The binding isotherms for decanoate and octanoate could not be fitted by the general bindin......(6) and 1.4 X 10(5) M-1 for decanoate, approximately 0.5 of the mercaptalbumin having high affinity. Udgivelsesdato: 1988-May-15...... equation. It was necessary to assume the presence of two albumin components, one with high affinity and one with low affinity, about 0.65 of the albumin having high binding affinity. The first stoichiometric binding constants for the high- and low-affinity albumin components were 1.1 X 10(7) and 1.4 X 10(5......) M-1, respectively, for decanoate; 1.6 X 10(6) and 3.5 X 10(4) for octanoate; and 7.1 X 10(4) and 8.0 X 10(2) M-1 for hexanoate. The high-affinity albumin component binds 1 mol decanoate, 1 mol octanoate, or 2 mol hexanoate more than is bound to the low-affinity component. Chloride ions compete...

  17. Detection of carrier heterogeneity by rate of ligand dialysis: medium-chain fatty acid interaction with human serum albumin and competition with chloride

    DEFF Research Database (Denmark)

    Honoré, B; Brodersen, R

    1988-01-01

    Binding equilibria for decanoate, octanoate, and hexanoate to defatted human serum albumin were investigated by dialysis exchange rate determinations in 66 mM sodium phosphate buffer, pH 7.4, 37 degrees C. The binding isotherms for decanoate and octanoate could not be fitted by the general binding...... equation. It was necessary to assume the presence of two albumin components, one with high affinity and one with low affinity, about 0.65 of the albumin having high binding affinity. The first stoichiometric binding constants for the high- and low-affinity albumin components were 1.1 X 10(7) and 1.4 X 10......(5) M-1, respectively, for decanoate; 1.6 X 10(6) and 3.5 X 10(4) for octanoate; and 7.1 X 10(4) and 8.0 X 10(2) M-1 for hexanoate. The high-affinity albumin component binds 1 mol decanoate, 1 mol octanoate, or 2 mol hexanoate more than is bound to the low-affinity component. Chloride ions compete...

  18. Fluorescence studies by quenching and protein unfolding on the interaction of bioactive compounds in water extracts of kiwi fruit cultivars with human serum albumin

    International Nuclear Information System (INIS)

    Seo Park, Yong; Polovka, Martin; Leticia Martinez-Ayala, Alma; González-Aguilar, Gustavo A.; Ham, Kyung-Sik; Kang, Seong-Gook; Park, Yang-Kyun; Heo, Buk-Gu; Namiesnik, Jacek; Gorinstein, Shela

    2015-01-01

    The main aim of this investigation was to characterize new kiwi fruit cultivars after cold storage treatment and to determine the similarities and differences between them, using spectroscopic methods. The chemometric comparison of kiwi fruit cultivars based on physicochemical indices during cold storage was carried out. All kiwi fruit cultivars showed a high level of correlation between the contents of phenolic compounds (polyphenols, tannins and flavonoids) and their antioxidant capacities. The interactions of soluble polyphenols of different kiwi fruit cultivars with human serum albumin (HSA) were investigated by fluorescence. The obtained statistical and fluorescence results allow to classify the investigated kiwi fruit cultivars according to their properties. The antioxidant properties of different cultivars monitored by β-carotene assay showed that the highest percentage of antioxidant activity (%AA) at the end of the cold storage was detected for ‘SKK-12’ (27.61±2.44) %AA with the lowest shelf life (8 weeks) and the lowest was found for ‘Hayward’ variety (8.33±0.74) %AA with the highest shelf life (24 weeks). The averaged amount of polyphenols in ‘Bidan’ and ‘SKK-12’ 13.97±1.95 mg GAE/g was much higher than in other cultivars 3.93±3.26 mg GAE/g, without respect on time of cold storage. The HSA-binding capacities of these cultivars were the highest and correlated with their antioxidant capacities. To our knowledge this is the first report showing differences and similarities in new kiwi fruit cultivars, using spectroscopic techniques. The fact that fluorescence spectral methods are applied as a powerful tool to show the photophysical properties of intrinsic fluorophores in protein molecules in the presence of fruit extracts is important in this study. In conclusion, the obtained knowledge would contribute to the pharmaceutical development and clinical application of kiwi fruit extracts. - Highlights: • Different kiwi fruit cultivars

  19. Comparative solution equilibrium studies on pentamethylcyclopentadienyl rhodium complexes of 2,2'-bipyridine and ethylenediamine and their interaction with human serum albumin.

    Science.gov (United States)

    Enyedy, Éva A; Mészáros, János P; Dömötör, Orsolya; Hackl, Carmen M; Roller, Alexander; Keppler, Bernhard K; Kandioller, Wolfgang

    2015-11-01

    Complex formation equilibrium processes of the (N,N) donor containing 2,2'-bipyridine (bpy) and ethylenediamine (en) with (η(5)-pentamethylcyclopentadienyl)rhodium(III) were investigated in aqueous solution via pH-potentiometry, (1)H NMR spectroscopy, and UV-vis spectrophotometry in the absence and presence of chloride ions. The structure of [RhCp*(en)Cl]ClO4 (Cp*, pentamethylcyclopentadienyl) was also studied by single-crystal X-ray diffraction. pKa values of 8.56 and 9.58 were determined for [RhCp*(bpy)(H2O)](2+) and [RhCp*(en)(H2O)](2+), respectively resulting in the formation of negligible amount of mixed hydroxido complexes at pH 7.4. Stability and the H2O/Cl(-) co-ligand exchange constants of bpy and en complexes considerably exceed those of the bidentate O-donor deferiprone. The strong affinity of the bpy and en complexes to chloride ions most probably contributes to their low antiproliferative effect. Interactions between human serum albumin (HSA) and [RhCp*(H2O)3](2+), its complexes formed with deferiprone, bpy and en were also monitored by (1)H NMR spectroscopy, ultrafiltration/UV-vis and spectrofluorometry. Numerous binding sites (≥ 8) are available for [RhCp*(H2O)3](2+); and the interaction takes place most probably via covalent bonds through the imidazole nitrogen of His. According to the various fluorescence studies [RhCp*(H2O)3](2+) binds on sites I and II, and coordination of surface side chain donor atoms of the protein is also feasible. The binding of the bpy and en complex is weaker and slower compared to that of [RhCp*(H2O)3](2+), and formation of ternary HSA-RhCp*-ligand adducts was proved. In the case of the deferiprone complex, the RhCp* fragment is cleaved off when HSA is loaded with low equivalents of the compound.

  20. Fluorescence studies by quenching and protein unfolding on the interaction of bioactive compounds in water extracts of kiwi fruit cultivars with human serum albumin

    Energy Technology Data Exchange (ETDEWEB)

    Seo Park, Yong, E-mail: ypark@mokpo.ac.kr [Department of Horticultural Science, Mokpo National University, Muan, Jeonnam (Korea, Republic of); Polovka, Martin [National Agricultural and Food Centre VUP, Food Research Institute, SK-824 75 Bratislava (Slovakia); Leticia Martinez-Ayala, Alma [Centro de Desarrollo de Productos Bioticos, Instituto Politécnico Nacional, Carretera Yautepec-Jojutla, Km. 6, calle CEPROBI No. 8, Col. San Isidro, Yautepec, Morelos 62731 (Mexico); González-Aguilar, Gustavo A. [Research Center for Food & Development, A.C. (CIAD), Carretera a Ejido La Victoria, Km 0.6, Hermosillo, Sonora 83304 (Mexico); Ham, Kyung-Sik; Kang, Seong-Gook; Park, Yang-Kyun [Department of Food Engineering, Mokpo National University, Muan, Jeonnam (Korea, Republic of); Heo, Buk-Gu [Naju Foundation of Natural Dyeing Culture, Naju 520-931 (Korea, Republic of); Namiesnik, Jacek [Department of Analytical Chemistry, Chemical Faculty, Gdańsk University of Technology, 80 952 Gdańsk (Poland); Gorinstein, Shela, E-mail: shela.gorin@mail.huji.ac.il [The Institute for Drug Research, School of Pharmacy, The Hebrew University, Hadassah Medical School, Jerusalem 91120 (Israel)

    2015-04-15

    The main aim of this investigation was to characterize new kiwi fruit cultivars after cold storage treatment and to determine the similarities and differences between them, using spectroscopic methods. The chemometric comparison of kiwi fruit cultivars based on physicochemical indices during cold storage was carried out. All kiwi fruit cultivars showed a high level of correlation between the contents of phenolic compounds (polyphenols, tannins and flavonoids) and their antioxidant capacities. The interactions of soluble polyphenols of different kiwi fruit cultivars with human serum albumin (HSA) were investigated by fluorescence. The obtained statistical and fluorescence results allow to classify the investigated kiwi fruit cultivars according to their properties. The antioxidant properties of different cultivars monitored by β-carotene assay showed that the highest percentage of antioxidant activity (%AA) at the end of the cold storage was detected for ‘SKK-12’ (27.61±2.44) %AA with the lowest shelf life (8 weeks) and the lowest was found for ‘Hayward’ variety (8.33±0.74) %AA with the highest shelf life (24 weeks). The averaged amount of polyphenols in ‘Bidan’ and ‘SKK-12’ 13.97±1.95 mg GAE/g was much higher than in other cultivars 3.93±3.26 mg GAE/g, without respect on time of cold storage. The HSA-binding capacities of these cultivars were the highest and correlated with their antioxidant capacities. To our knowledge this is the first report showing differences and similarities in new kiwi fruit cultivars, using spectroscopic techniques. The fact that fluorescence spectral methods are applied as a powerful tool to show the photophysical properties of intrinsic fluorophores in protein molecules in the presence of fruit extracts is important in this study. In conclusion, the obtained knowledge would contribute to the pharmaceutical development and clinical application of kiwi fruit extracts. - Highlights: • Different kiwi fruit cultivars

  1. Induced self-assembly and Förster resonance energy transfer studies of alkynylplatinum(II) terpyridine complex through interaction with water-soluble poly(phenylene ethynylene sulfonate) and the proof-of-principle demonstration of this two-component ensemble for selective label-free detection of human serum albumin.

    Science.gov (United States)

    Chung, Clive Yik-Sham; Yam, Vivian Wing-Wah

    2011-11-23

    The interaction of conjugated polyelectrolyte, PPE-SO(3)(-), with platinum(II) complexes, [Pt(tpy)(C≡CC(6)H(4)-CH(2)NMe(3)-4)](OTf)(2) (1) and [Pt(tpy)(C≡C-CH(2)NMe(3))](OTf)(2) (2), has been studied by UV-vis, and steady-state and time-resolved emission spectroscopy. A unique FRET from PPE-SO(3)(-) to the aggregated complex 1 on the polymer chain with Pt···Pt interaction has been demonstrated, resulting in the growth of triplet metal-metal-to-ligand charge transfer ((3)MMLCT) emission in the near-infrared (NIR) region. This two-component ensemble has been employed in a "proof-of-principle" concept for the sensitive and selective label-free detection of human serum albumin (HSA) by the emission spectral changes in the visible and in the NIR region. The spectral changes have been ascribed to the disassembly of the polymer-metal complex aggregates upon the binding of PPE-SO(3)(-) to HSA, which is rich in arginine residues and hydrophobic patches, leading to the decrease in FRET from PPE-SO(3)(-) to the aggregated platinum(II) complex. The ensemble is found to have high selectivity toward HSA over a number of polyelectrolytes, proteins and small amino acids. This has been suggested to be a result of the extra stabilization gained from the Pt···Pt and π-π interactions in addition to the electrostatic and hydrophobic interactions found in the polymer-metal complex aggregates.

  2. Design-overlay interactions in metal double patterning

    Science.gov (United States)

    Ghaida, Rani S.; Gupta, Puneet

    2009-03-01

    In double patterning lithography (DPL), overlay error between two patterning steps at the same layer translates into CD variability. Since CD uniformity budget is very tight, overlay control becomes a tough challenge for DPL. In this paper, we electrically evaluate overlay error for BEOL DPL with the goal of studying relative effects of different overlay sources and interactions of overlay control with design parameters. Experimental results show the following: (a) overlay electrical impact is not significant in case of positive-tone DPL (DPL; (c) Design For Manufacturability (DFM) techniques like wire spreading can have a large effect on overlay electrical impact (20% increase of spacing can reduce capacitance variation by 22%); (d) translation overlay has the largest electrical impact compared to other overlay sources; and (e) overlay in y direction (x for horizontal metalization) has negligible electrical impact and, therefore, preferred routing direction should be taken into account for overlay sampling and alignment strategies.

  3. Strong delayed interactive effects of metal exposure and warming

    DEFF Research Database (Denmark)

    Debecker, Sara; Dinh, Khuong Van; Stoks, Robby

    2017-01-01

    As contaminants are often more toxic at higher temperatures, predicting their impact under global warming remains a key challenge for ecological risk assessment. Ignoring delayed effects, synergistic interactions between contaminants and warming, and differences in sensitivity across species......’ ranges could lead to an important underestimation of the risks. We addressed all three mechanisms by studying effects of larval exposure to zinc and warming before, during, and after metamorphosis in Ischnura elegans damselflies from high- and lowlatitude populations. By integrating these mechanisms...... was especially remarkable in high-latitude animals, as they appeared almost insensitive to zinc during the larval stage. Second, the well-known synergism between metals and warming was manifested not only during the larval stage but also after metamorphosis, yet notably only in low-latitude damselflies...

  4. Study on the interactions of sulfonylurea antidiabetic drugs with normal and glycated human serum albumin by capillary electrophoresis-frontal analysis.

    Science.gov (United States)

    Michalcová, Lenka; Glatz, Zdeněk

    2016-09-01

    Diabetes is one of the most widespread diseases characterized by a deficiency in the production of insulin or its ineffectiveness. As a result, the increased concentrations of glucose in the blood lead not only to damage to many of the body's systems but also cause the nonenzymatic glycation of plasma proteins affecting their drug binding. Since the binding ability influences its pharmacokinetics and pharmacodynamics, this is a very important issue in the development of new drugs and personalized medicine. In this study, capillary electrophoresis-frontal analysis was used to evaluate the affinities between human serum albumin or its glycated form and the first generation of sulfonylurea antidiabetics, since their inadequate concentration may induce hypoglycaemia or on the contrary hyperglycaemia. The binding constants decrease in the sequence acetohexamide > tolbutamide > chlorpropamide > carbutamide both for normal and glycated human serum albumins, with glycated giving lower values. These results provide a more quantitative picture of how these drugs bind with normal and modified human serum albumin and indicate capillary electrophoresis-frontal analysis to be another tool for examining the changes arising from modifications of albumin, or any other protein, with all its benefits like short analysis time, small sample requirement, and automation. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Anomalous carrier life-time relaxation mediated by head group interaction in surface anchored MnSe quantum dots conjugated with albumin proteins

    Energy Technology Data Exchange (ETDEWEB)

    Sarma, Runjun; Mohanta, Dambarudhar, E-mail: best@tezu.ernet.in

    2017-02-01

    We report on the radiative emission decay dynamics of a less known, γ-phase manganese selenide quantum dot system (MnSe QDs) subjected to bio-functionalization. A short-ligand thioglycolic acid (TGA), and a long-chain sodium dodecyl sulfate (SDS) surfactants were used as surface anchors prior bioconjugation with albumin proteins (BSA). Time resolved photoluminescence (TR-PL) spectra of the QDs have revealed bi-exponential decay trends with the fast (τ{sub 1}) and slow (τ{sub 2}) decay parameters assigned to the core state recombination and surface trapped excitons; respectively. The average lifetime (τ{sub avg}) was found to get shortened from a value of ∼0.87 ns–0.72 ns in unconjugated and BSA conjugated MnSe-TGA QDs; respectively. Conversely, MnSe-SDS QDs with BSA conjugation exhibited nearly four-fold enhancement of τ{sub avg} with respect to its unconjugated counterpart. Moreover, a considerable amount of Förster resonance energy transfer (FRET) was found to occur from the TGA coated MnSe QDs to BSA and with an ensuing efficiency of ∼61%. The origin of anomalous carrier life-time relaxation features has also been encountered through a simplified model as regards head group interaction experienced by the MnSe QDs with different surfactant types. Exploiting luminescence decay characteristics of a magneto-fluorescent candidate could find immense scope in diverse biological applications including assays, labeling and imaging. - Highlights: • Surface anchored manganese selenide quantum dots (MnSe QDs) have been synthesized via a physico-chemical reduction route. • Time resolved luminescence spectra of the QDs have displayed bi-exponential decay trend. • Thioglycolic acid (TGA) coated QDs exhibited shorter lifetime as compared to sodium dodecyl sulfo-succinate (SDS) coated ones. • Upon BSA conjugation, the average life time is four-fold enhanced in MnSe-SDS QDs. • An efficient FRET process has been revealed in BSA conjugated TGA coated MnSe QDs.

  6. Universal interaction-driven gap in metallic carbon nanotubes

    Science.gov (United States)

    Senger, Mitchell J.; McCulley, Daniel R.; Lotfizadeh, Neda; Deshpande, Vikram V.; Minot, Ethan D.

    2018-02-01

    Suspended metallic carbon nanotubes (m-CNTs) exhibit a remarkably large transport gap that can exceed 100 meV. Both experiment and theory suggest that strong electron-electron interactions play a crucial role in generating this electronic structure. To further understand this strongly interacting system, we have performed electronic measurements of suspended m-CNTs with known diameter and chiral angle. Spectrally resolved photocurrent microscopy was used to determine m-CNT structure. The room-temperature electrical characteristics of 18 individually contacted m-CNTs were compared to their respective diameter and chiral angle. At the charge neutrality point, we observe a peak in m-CNT resistance that scales exponentially with inverse diameter. Using a thermally activated transport model, we estimate that the transport gap is (450 meV nm)/D , where D is CNT diameter. We find no correlation between the gap and the CNT chiral angle. Our results add important constraints to theories attempting to describe the electronic structure of m-CNTs.

  7. Thermodynamics of binding interactions between extracellular polymeric substances and heavy metals by isothermal titration microcalorimetry.

    Science.gov (United States)

    Yan, Peng; Xia, Jia-Shuai; Chen, You-Peng; Liu, Zhi-Ping; Guo, Jin-Song; Shen, Yu; Zhang, Cheng-Cheng; Wang, Jing

    2017-05-01

    Extracellular polymeric substances (EPS) play a crucial role in heavy metal bio-adsorption using activated sludge, but the interaction mechanism between heavy metals and EPS remains unclear. Isothermal titration calorimetry was employed to illuminate the mechanism in this study. The results indicate that binding between heavy metals and EPS is spontaneous and driven mainly by enthalpy change. Extracellular proteins in EPS are major participants in the binding process. Environmental conditions have significant impact on the adsorption performance. Divalent and trivalent cations severely impeded the binding of heavy metal ions to EPS. Electrostatic interaction mainly attributed to competition between divalent cations and heavy metal ions; trivalent cations directly competed with heavy metal ions for EPS binding sites. Trivalent cations were more competitive than divalent cations for heavy metal ion binding because they formed complexing bonds. This study facilitates a better understanding about the interaction between heavy metals and EPS in wastewater treatment. Copyright © 2017 Elsevier Ltd. All rights reserved.

  8. The Biomechanisms of Metal and Metal-Oxide Nanoparticles’ Interactions with Cells

    Directory of Open Access Journals (Sweden)

    Sondra S. Teske

    2015-01-01

    Full Text Available Humans are increasingly exposed to nanoparticles (NPs in medicine and in industrial settings, where significant concentrations of NPs are common. However, NP interactions with and effects on biomolecules and organisms have only recently been addressed. Within we review the literature regarding proposed modes of action for metal and metal-oxide NPs, two of the most prevalent types manufactured. Iron-oxide NPs, for instance, are used as tracers for magnetic resonance imaging of oncological tumors and as vehicles for therapeutic drug delivery. Factors and theories that determine the physicochemical and biokinetic behaviors of NPs are discussed, along with the observed toxicological effects of NPs on cells. Key thermodynamic and kinetic models that explain the sources of energy transfer from NPs to biological targets are summarized, in addition to quantitative structural activity relationship (QSAR modeling efforts. Future challenges for nanotoxicological research are discussed. We conclude that NP studies based on cell culture are often inconsistent and underestimate the toxicity of NPs. Thus, the effect of NPs needs to be examined in whole animal systems.

  9. Interactions between metal cations with H2 in the M - H2 complexes ...

    Indian Academy of Sciences (India)

    Interaction; metal cation–dihydrogen complexes; well depth; binding energy; PECs; energy components; DHDF; CCSD(T); SAPT; NBO. 1. Introduction. Interactions between metal cations and neutral molecu- les play important roles in a variety of contexts including gas storage in solid materials, ion solvation, laser plas-.

  10. Heat energy from hydrogen-metal nuclear interactions

    Science.gov (United States)

    Hadjichristos, John; Gluck, Peter

    2013-11-01

    The discovery of the Fleischmann-Pons Effect in 1989, a promise of an abundant, cheap and clean energy source was premature in the sense that theoretical knowledge, relative technologies and the experimental tools necessary for understanding and for scale-up still were not available. Therefore the field, despite efforts and diversification remained quasi-stagnant, the effect (a scientific certainty) being of low intensity leading to mainstream science to reject the phenomenon and not supporting its study. Recently however, the situation has changed, a new paradigm is in statunascendi and the obstacles are systematically removed by innovative approaches. Defkalion, a Greek company (that recently moved in Canada for faster progress) has elaborated an original technology for the Ni-H system [1-3]. It is about the activation of hydrogen and creation of nuclear active nano-cavities in the metal through a multi-stage interaction, materializing some recent breakthrough announcements in nanotechnology, superconductivity, plasma physics, astrophysics and material science. A pre-industrial generator and a novel mass-spectrometry instrumentations were created. Simultaneously, a meta-theory of phenomena was sketched in collaboration with Prof. Y. Kim (Purdue U).

  11. Sex-specific Profiles of Blood Metal Levels Associated with Metal–Iron Interactions

    OpenAIRE

    Lee, Byung-Kook; Kim, Yangho

    2014-01-01

    The mechanisms by which iron is absorbed are similar to those of divalent metals, particularly manganese, lead, and cadmium. These metals, however, show different toxicokinetics in relation to menarche or menopause, although their interaction with iron is the same. This review focuses on the kinetics of these three toxic metals (manganese, lead, and cadmium) in relation to menarche, pregnancy, and menopause. The iron–manganese interaction is the major factor determining sex-specific differenc...

  12. Interaction between the Natural Components in Danhong Injection (DHI) with Serum Albumin (SA) and the Influence of the Coexisting Multi-Components on the SaB-BSA Binding System: Fluorescence and Molecular Docking Studies

    Science.gov (United States)

    Hao, Jia; Zhang, Yingyue; Wang, Xingrui; Yan, Huo; Liu, Erwei; Gao, Xiumei

    2015-01-01

    Danhong injection (DHI) is a widely used Chinese Materia Medica standardized product for the clinical treatment of ischemic encephalopathy and coronary heart disease. The bindings of eight natural components in DHI between bovine serum albumin (BSA) were studied by fluorescence spectroscopy technology and molecular docking. According to the results, the quenching process of salvianolic acid B and hydroxysafflor yellow A was a static quenching procedure through the analysis of quenching data by the Stern-Volmer equation, the modified Stern-Volmer equation, and the modified Scatchard equation. Meanwhile, syringin (Syr) enhanced the fluorescence of BSA, and the data were analyzed using the Lineweaver-Burk equation. Molecular docking suggested that all of these natural components bind to serum albumin at the site I location. Further competitive experiments of SaB confirmed the result of molecular docking studies duo to the displacement of warfarin by SaB. Base on these studies, we selected SaB as a research target because it presented the strongest binding ability to BSA and investigated the influence of the multi-components coexisting in DHI on the interaction between the components of the SaB-BSA binding system. The participation of these natural components in DHI affected the interaction between the components of the SaB-BSA system. Therefore, when DHI is used in mammals, SaB is released from serum albumin more quickly than it is used alone. This work would provide a new experiment basis for revealing the scientific principle of compatibility for Traditional Chinese Medicine. PMID:26035712

  13. Palmitate binding to serum albumin, measured by rate of dialysis

    DEFF Research Database (Denmark)

    Brodersen, R; Honoré, B; Andersen, S

    1988-01-01

    with binding of the unsaturated acids is less pronounced. Chloride ions compete with binding of palmitate. Reserve albumin concentration in serum samples from 33 male adults was 420 +/- 59 microM (mean +/- SD), and in 33 females, 351 +/- 50 microM. Umbilical cord sera from ten newborn infants averaged 172......, using pure albumin solutions, we obtained the reserve albumin concentration for binding of palmitate, previously defined as the concentration of a pure standard albumin which binds the labelled ligand as tightly as it is bound in the sample. Two techniques were developed, one for 1-ml sample volumes......, another for 25 microliter. Reserve albumin for binding of palmitate, measured in pure albumin solutions, decreased equally on addition of palmitate and stearate, slightly less with oleate and still less with linoleate, indicating that palmitate and stearate are bound competitively while interaction...

  14. Trace Metal Requirements and Interactions in Symbiodinium kawagutii

    OpenAIRE

    Irene B. Rodriguez; Tung-Yuan Ho; Tung-Yuan Ho

    2018-01-01

    Photosynthetic organisms need trace metals for various biological processes and different groups of microalgae have distinctive obligate necessities due to their respective biochemical requirements and ecological niches. We have previously shown that the dinoflagellate Symbiodinium kawagutii requires high concentrations of bioavailable Fe to achieve optimum growth. Here, we further explored the trace metal requirements of S. kawagutii with intensive focus on the effect of individual metal and...

  15. Interaction of NO2 with model NSR catalysts: metal-oxide interaction controls initial NOx storage mechanism.

    Science.gov (United States)

    Desikusumastuti, Aine; Staudt, Thorsten; Qin, Zhihui; Happel, Markus; Laurin, Mathias; Lykhach, Yaroslava; Shaikhutdinov, Shamil; Rohr, Friedemann; Libuda, Jörg

    2008-10-24

    Using scanning tunneling microscopy (STM), molecular-beam (MB) methods and time-resolved infrared reflection absorption spectroscopy (TR-IRAS), we investigate the mechanism of initial NO(x) uptake on a model nitrogen storage and reduction (NSR) catalyst. The model system is prepared by co-deposition of Pd metal particles and Ba-containing oxide particles onto an ordered alumina film on NiAl(110). We show that the metal-oxide interaction between the active noble metal particles and the NO(x) storage compound in NSR model catalysts plays an important role in the reaction mechanism. We suggest that strong interaction facilitates reverse spillover of activated oxygen species from the NO(x) storage compound to the metal. This process leads to partial oxidation of the metal nanoparticles and simultaneous stabilization of the surface nitrite intermediate.

  16. Quantifying the interactions among metal mixtures in toxicodynamic process with generalized linear model.

    Science.gov (United States)

    Feng, Jianfeng; Gao, Yongfei; Ji, Yijun; Zhu, Lin

    2018-03-05

    Predicting the toxicity of chemical mixtures is difficult because of the additive, antagonistic, or synergistic interactions among the mixture components. Antagonistic and synergistic interactions are dominant in metal mixtures, and their distributions may correlate with exposure concentrations. However, whether the interaction types of metal mixtures change at different time points during toxicodynamic (TD) processes is undetermined because of insufficient appropriate models and metal bioaccumulation data at different time points. In the present study, the generalized linear model (GLM) was used to illustrate the combined toxicities of binary metal mixtures, such as Cu-Zn, Cu-Cd, and Cd-Pb, to zebrafish larvae (Danio rerio). GLM was also used to identify possible interaction types among these method for the traditional concentration addition (CA) and independent action (IA) models. Then the GLM were applied to quantify the different possible interaction types for metal mixture toxicity (Cu-Zn, Cu-Cd, and Cd-Pb to D. rerio and Ni-Co to Oligochaeta Enchytraeus crypticus) during the TD process at different exposure times. We found different metal interaction responses in the TD process and interactive coefficients significantly changed at different exposure times (pmixture toxicology on organisms. Moreover, care should be taken when evaluating interactions in toxicity prediction because results may vary at different time points. The GLM could be an alternative or complementary approach for BLM to analyze and predict metal mixture toxicity. Copyright © 2017 Elsevier B.V. All rights reserved.

  17. Crystallographic analysis of the ternary complex of octanoate and N-acetyl-l-methionine with human serum albumin reveals the mode of their stabilizing interactions.

    Science.gov (United States)

    Kawai, Akito; Chuang, Victor T G; Kouno, Yosuke; Yamasaki, Keishi; Miyamoto, Shuichi; Anraku, Makoto; Otagiri, Masaki

    2017-08-01

    During pasteurization and storage of albumin products, Sodium octanoate (Oct) and N-acethyl-l-tryptophan (N-AcTrp) are used as the thermal stabilizer and the antioxidant for human serum albumin (HSA), respectively. We recently reported that N-acethyl-l-methionine (N-AcMet) is an antioxidant for HSA, which is superior to N-AcTrp when it is especially exposed to light during storage. The objective of the present study is to clarify the molecular mechanism responsible for the HSA protective effect of Oct and N-AcMet based on their ternary complex structure. Crystal structure of the HSA-Oct-N-AcMet complex showed that one N-AcMet molecule is bound to the entrance of drug site 1 of HSA, and its side chain, which is susceptible to the oxidation, is exposed to the solvent. At the same time, two Oct binding sites are observed in drug sites 1 and 2 of HSA, respectively, and each Oct molecule occupies the hydrophobic cavity in them. These results indicate the molecular mechanism responsible for the HSA stabilization by these small molecules as follows. N-AcMet seals the entrance of drug site 1 while it acts as an antioxidant for HSA. Oct is chiefly bound to drug site 2 of HSA and it increases the thermal stability of HSA because of the occupying the largest intra-cavity of sub-domain IIIA in HSA. These findings suggest that N-AcMet acts positively as useful stabilizer for albumin formulated products such as functionalized HSA and HSA fusion proteins. Copyright © 2017 Elsevier B.V. All rights reserved.

  18. Graphene-metal interaction and its effect on the interface stability under ambient conditions

    Energy Technology Data Exchange (ETDEWEB)

    Dong, Aiyi; Fu, Qiang, E-mail: qfu@dicp.ac.cn; Wei, Mingming; Bao, Xinhe

    2017-08-01

    Highlights: • Graphene (Gr)/transition metal (TM: Fe, Co, Pt, and Au) interfaces form through TM intercalation at Gr/Ru(0001) surface. • Graphene-metal interaction strength follows the order of Ru ≈ Fe ≈ Co > Pt > Au. • Oxygen intercalation occurs at Gr/Fe, Gr/Co, Gr/Pt, and Gr/Ru interfaces but not at Gr/Au interface in air around 100 °C. - Abstract: Interaction between graphene (Gr) and metal plays an important role in physics and chemistry of graphene/metal interfaces. In this work, well-defined interfaces between graphene and transition metals (TMs) including Fe, Co, Pt, and Au were prepared through TM intercalation on Gr/Ru(0001) surface. The Gr-metal interaction was investigated using X-ray photoelectron spectroscopy and ultraviolet photoelectron spectroscopy. We found that graphene interacts most strongly with Ru, Fe and Co and most weakly with Au, following the order of Ru ≈ Fe ≈ Co > Pt > Au. The Gr/Fe, Gr/Co, Gr/Pt, and Gr/Ru interfaces can be readily intercalated by oxygen when exposed to air and illuminated by an infrared lamp. In contrast, oxygen intercalation does not happen at the Gr/Au interface under the same condition. It is suggested that both Gr-metal interaction and oxygen adsorption on the underlying metal surface are critical in the oxygen intercalation and the Gr/metal interface stability.

  19. Understanding Metallic Bonding: Structure, Process and Interaction by Rasch Analysis

    Science.gov (United States)

    Cheng, Maurice M. W.; Oon, Pey-Tee

    2016-01-01

    This paper reports the results of a survey of 3006 Year 10-12 students on their understandings of metallic bonding. The instrument was developed based on Chi's ontological categories of scientific concepts and students' understanding of metallic bonding as reported in the literature. The instrument has two parts. Part one probed into students'…

  20. Interaction of Hydroxyproline with Bivalent Metal Ions in Chemical ...

    African Journals Online (AJOL)

    NICO

    The stability constants of the ML and ML2 complex species of some metal ions, namely beryllium(II) and cobalt(II), with hydroxyproline were ... metal ions have several significant applications in biological systems.3–20 Beryllium is one ... 1 filter paper for chromatography was used for the purpose of electrophoresis. An Elico ...

  1. Interaction of hydrogen and oxygen with bulk defects and surfaces of metals

    International Nuclear Information System (INIS)

    Besenbacher, F.

    1994-05-01

    The thesis deals with the interaction of hydrogen with defects in metals and the interaction of hydrogen and oxygen with metal surfaces studied by ion-beam techniques and scanning tunneling microscopy (STM), respectively. The first part of the thesis discusses the interaction of hydrogen with simple defects in transition metals. The trap-binding enthalpies and the lattice location of hydrogen trapped to vacancies have been determined, and an extremely simple and versatile picture of the hydrogen-metal interaction has evolved, in which the trap strength is mainly determined by the local electron density. Any dilution of the lattice will lead to a trap, vacancies and voids being the strongest trap. It is found that hydrogen trapped to vacancies in fcc metals is quantum-mechanically delocalized, and the excitation energies for the hydrogen in the vacancy potential are a few MeV only. The interaction of hydrogen with metal surfaces is studied by the transmission channeling (TC) technique. It is found that hydrogen chemisorbs in the highest-coordinated sites on the surfaces, and that there is a direct relationship between the hydrogen-metal bond length and the coordination number for the hydrogen. In the final part of the thesis the dynamics of the chemisorption process for oxygen and hydrogen on metal surfaces is studied by STM, a fascinating and powerful technique for exploring the atomic-scale realm of surfaces. It is found that there is a strong coupling between the chemisorption process and the distortion of the metal surface. The adsorbates induce a surface reconstruction, i.e. metal-metal bond breaks and metal-adsorbate bounds form. Whereas hydrogen interacts weakly with the metals and induces reconstructions where only nnn metals bonds are broken, oxygen interacts strongly with the metal, and the driving force for the O-induced reconstructions appears to be the formation of low-coordinated metal-O rows, formed by breaking of nn metal bonds. Finally it is shown

  2. Interaction of antihypertensive drug amiloride with metal ions in micellar medium using fluorescence spectroscopy

    International Nuclear Information System (INIS)

    Gujar, Varsha; Pundge, Vijaykumar; Ottoor, Divya

    2015-01-01

    Steady state and life time fluorescence spectroscopy have been employed to study the interaction of antihypertensive drug amiloride with biologically important metal ions i.e. Cu 2+ , Fe 2+ , Ni 2+ and Zn 2+ in various micellar media (anionic SDS (sodium dodecyl sulfate), nonionic TX-100 (triton X-100) and cationic CTAB (cetyl trimethyl ammonium bromide)). It was observed that fluorescence properties of drug remain unaltered in the absence of micellar media with increasing concentration of metal ions. However, addition of Cu 2+ , Fe 2+ and Ni 2+ caused fluorescence quenching of amiloride in the presence of anionic micelle, SDS. Binding of drug with metal ions at the charged micellar interface could be the possible reason for this pH-dependent metal-mediated fluorescence quenching. There were no remarkable changes observed due to metal ions addition when drug was present in cationic and nonionic micellar medium. The binding constant and bimolecular quenching constant were evaluated and compared for the drug–metal complexes using Stern–Volmer equation and fluorescence lifetime values. - Highlights: • Interaction of amiloride with biologically important metal ions, Fe 2+ , Cu 2+ , Ni 2+ and Zn 2+ . • Monitoring the interaction in various micelle at different pH by fluorescence spectroscopy. • Micelles acts as receptor, amiloride as transducer and metal ions as analyte in the present system. • Interaction study provides pH dependent quenching and binding mechanism of drug with metal ions

  3. DNA interactions and biocidal activity of metal complexes of ...

    Indian Academy of Sciences (India)

    Narendrula Vamsikrishna

    115.3. 2.4 Synthesis of metal complexes. To a hot methanolic solution of the Schiff base [2-(-(benzo. [d]thiazol-6-ylimino)methyl)-4-chlorophenol/2-(-(benzo[d] thiazol-6-ylimino)methyl)-4-nitrophenol] (10 mmol), a solu- tion of metal(II) acetate of copper, nickel or cobalt (10 mmol) in hot methanol was added drop wise and the ...

  4. Urinary albumin in space missions

    DEFF Research Database (Denmark)

    Cirillo, Massimo; De Santo, Natale G; Heer, Martina

    2002-01-01

    Proteinuria was hypothesized for space mission but research data are missing. Urinary albumin, as index of proteinuria, was analyzed in frozen urine samples collected by astronauts during space missions onboard MIR station and on ground (control). Urinary albumin was measured by a double antibody...... radioimmunoassay. On average, 24h urinary albumin was 27.4% lower in space than on ground; the difference was statistically significant. Low urinary albumin excretion could be another effect of exposure to weightlessness (microgravity)....

  5. (PCG) Protein Crystal Growth Human Serum Albumin

    Science.gov (United States)

    1989-01-01

    (PCG) Protein Crystal Growth Human Serum Albumin. Contributes to many transport and regulatory processes and has multifunctional binding properties which range from various metals, to fatty acids, hormones, and a wide spectrum of therapeutic drugs. The most abundant protein of the circulatory system. It binds and transports an incredible variety of biological and pharmaceutical ligands throughout the blood stream. Principal Investigator on STS-26 was Larry DeLucas.

  6. Interactions between salt marsh plants and Cu nanoparticles - Effects on metal uptake and phytoremediation processes.

    Science.gov (United States)

    Andreotti, Federico; Mucha, Ana Paula; Caetano, Cátia; Rodrigues, Paula; Rocha Gomes, Carlos; Almeida, C Marisa R

    2015-10-01

    The increased use of metallic nanoparticles (NPs) raises the probability of finding NPs in the environment. A lot of information exists already regarding interactions between plants and metals, but information regarding interactions between metallic NPs and plants, including salt marsh plants, is still lacking. This work aimed to study interactions between CuO NPs and the salt marsh plants Halimione portulacoides and Phragmites australis. In addition, the potential of these plants for phytoremediation of Cu NPs was evaluated. Plants were exposed for 8 days to sediment elutriate solution doped either with CuO or with ionic Cu. Afterwards, total metal concentrations were determined in plant tissues. Both plants accumulated Cu in their roots, but this accumulation was 4 to 10 times lower when the metal was added in NP form. For P. australis, metal translocation occurred when the metal was added either in ionic or in NP form, but for H. portulacoides no metal translocation was observed when NPs were added to the medium. Therefore, interactions between plants and NPs differ with the plant species. These facts should be taken in consideration when applying these plants for phytoremediation of contaminated sediments in estuaries, as the environmental management of these very important ecological areas can be affected. Copyright © 2015 Elsevier Inc. All rights reserved.

  7. A synergistic effect of albumin and H₂O₂ accelerates corrosion of Ti6Al4V.

    Science.gov (United States)

    Yu, Fei; Addison, Owen; Davenport, Alison J

    2015-10-01

    The synergistic effect of albumin and H2O2 on corrosion of titanium alloy Ti6Al4V in physiological saline was investigated with long-term immersion tests and electrochemical methods. It was found that in the presence of both albumin and H2O2, the rate of metal release in immersion tests was far higher than in the presence of either species alone. Electrochemical polarisation curves and potentiostatic tests showed that H2O2 increased both the rates of the anodic and cathodic reactions, whilst albumin significantly decreased the rate of the cathodic reaction and slightly decreased the rate of the anodic reaction. The synergistic effect of albumin and H2O2 during immersion tests was attributed to the effect of adsorption of albumin in lowering the rate of the cathodic reaction and thus lowering the open circuit potential into the active region of titanium where complexation by H2O2 increased the corrosion rate. The corrosion attack was found to be greater in the β-phase of the alloy. The findings suggest that current standard tests in physiological or phosphate-buffered saline may underestimate the rate of corrosion in the peri-implant environment, in which albumin is the predominant protein, and reactive oxygen species such as H2O2 can occur as a result of inflammatory reactions in response to surgery, infection, or implant corrosion products. Corrosion of many biomedical implant materials occurs in the body leading to adverse biological responses. Several components of the environment into which a metal implant is placed including proteins and products of cellular physiology, been shown to modify corrosion resistance. Previously all studies on such components including the common protein albumin and the inflammatory product H2O2 have considered the effects of these species in isolation. For the first time we report a synergistic interaction between albumin and H2O2 significantly accelerating corrosion of Ti6Al4V at physiological pH and temperature. This is

  8. Interactions between plant hormones and heavy metals responses

    Directory of Open Access Journals (Sweden)

    Lauro Bücker-Neto

    2017-04-01

    Full Text Available Abstract Heavy metals are natural non-biodegradable constituents of the Earth's crust that accumulate and persist indefinitely in the ecosystem as a result of human activities. Since the industrial revolution, the concentration of cadmium, arsenic, lead, mercury and zinc, amongst others, have increasingly contaminated soil and water resources, leading to significant yield losses in plants. These issues have become an important concern of scientific interest. Understanding the molecular and physiological responses of plants to heavy metal stress is critical in order to maximize their productivity. Recent research has extended our view of how plant hormones can regulate and integrate growth responses to various environmental cues in order to sustain life. In the present review we discuss current knowledge about the role of the plant growth hormones abscisic acid, auxin, brassinosteroid and ethylene in signaling pathways, defense mechanisms and alleviation of heavy metal toxicity.

  9. Uptake of heavy metals by Typha capensis from wetland sites polluted by effluent from mineral processing plants: implications of metal-metal interactions.

    Science.gov (United States)

    Zaranyika, M F; Nyati, W

    2017-10-01

    The aim of the present work was to demonstrate the existence of metal-metal interactions in plants and their implications for the absorption of toxic elements like Cr. Typha capensis , a good accumulator of heavy metals, was chosen for the study. Levels of Fe, Cr, Ni, Cd, Pb, Cu and Zn were determined in the soil and roots, rhizomes, stems and leaves of T. capensis from three Sites A, B and C polluted by effluent from a chrome ore processing plant, a gold ore processing plant, and a nickel ore processing plant, respectively. The levels of Cr were extremely high at Site A at 5415 and 786-16,047 μg g -1 dry weight in the soil and the plant, respectively, while the levels of Ni were high at Site C at 176 and 24-891 μg g -1 in the soil and the plant, respectively. The levels of Fe were high at all three sites at 2502-7500 and 906-13,833 μg g -1 in the soil and plant, respectively. For the rest of the metals, levels were modest at 8.5-148 and 2-264 μg g -1 in the soil and plant, respectively. Pearson's correlation analysis confirmed mutual synergistic metal-metal interactions in the uptake of Zn, Cu, Co, Ni, Fe, and Cr, which are attributed to the similarity in the radii and coordination geometry of the cations of these elements. The implications of such metal-metal interactions (or effects of one metal on the behaviour of another) on the uptake of Cr, a toxic element, and possible Cr detoxification mechanism within the plant, are discussed.

  10. Adsorption of albumin and sodium hyaluronate on UHMWPE: a QCM-D and AFM study.

    Science.gov (United States)

    Serro, A P; Degiampietro, K; Colaço, R; Saramago, B

    2010-06-15

    The biotribological properties of artificial joints, in particular the efficiency of the lubrication, strongly determine their lifetime. The most commonly used artificial joints combine a metallic or ceramic part articulating against a ultra high molecular weight polyethylene (UHMWPE) counterface, and are lubricated by the periprosthetic fluid. This fluid contains several macromolecules, namely albumin and sodium hyaluronate (NaHA), that are known to be involved in the lubrication process. There are several studies in the literature concerning the interaction of the referred macromolecules with ceramic or metallic prosthetic materials. However, to our knowledge, information about their binding to the polymeric surface is practically inexistent. The objective of this work is to contribute to clarify the role played by albumin and NaHA on the biolubrication process, through the investigation of their interaction with the UHMWPE surface. The study involves adsorption measurements using a quartz crystal microbalance with dissipation (QCM-D), the characterization of the adsorbed films by atomic force microscopy (AFM) and wettability determinations. Albumin was found to adsorb strongly and extensively to the polymer, while NaHA led to a very low adsorption. In both cases rigid films were obtained, but with different morphology and porosity. The high binding affinity of the protein to the polymer was demonstrated both by the results of the fittings to Langmuir and Freundlich models and by the values of the adhesion forces determined by AFM. In the simultaneous adsorption of albumin and NaHA, protein adsorption is predominant and determines the surface properties. Copyright 2010 Elsevier B.V. All rights reserved.

  11. The role of metal ion-ligand interactions during divalent metal ion adsorption.

    Science.gov (United States)

    Eldridge, Daniel S; Crawford, Russell J; Harding, Ian H

    2015-09-15

    A suite of seven different divalent metal ions (Ca(II), Cd(II), Cu(II), Mg(II), Ni(II), Pb(II), Zn(II)) was adsorbed from solution onto two Fe2O3 samples, quartz SiO2 and three different amphoteric polystyrene latices (containing amine and carboxyl functional groups). For the metal oxides, a high correlation was observed between the pH at which 50% of the metal was removed from solution (pH50) and the first hydrolysis constant for the metal ion (pK1). For the polystyrene latices, a much higher correlation was observed between the pH50 and pKc (equilibrium constant describing metal-carboxyl affinity) as opposed to pK1. These observations provide evidence of a strong relationship that exists between a metal's affinity for a particular ligand in solution and for that metal ion's affinity for the same ligand present as part of an adsorbing surface. The isoelectric point of the amphoteric latex surface can be increased by decreasing the carboxyl content of the latex surface. For all 7 metal ions, this resulted in a substantial decrease, for any given pH, in adsorption. We suggest that this may be partly due to the decreased carboxyl content, but is dominantly attributable to the presence of less favorable electrostatic conditions. This, in turn, demonstrates that electrostatics play a controlling role in metal ion adsorption onto amphoteric latex surfaces and, in addition to the nature of the metal ion, also controls the pH at which adsorption takes place. Crown Copyright © 2015. Published by Elsevier Inc. All rights reserved.

  12. Interaction of Hydroxyproline with Bivalent Metal Ions in Chemical ...

    African Journals Online (AJOL)

    Arecent technique involving the use of paper electrophoresis is described for the study of equilibria in binary complex systems in solution. The stability constants of the ML and ML2 complex species of some metal ions, namely beryllium(II) and cobalt(II), with hydroxyproline were determined in 0.1 mol L–1 perchloric acid ...

  13. Response of soil microbial communities and microbial interactions to long-term heavy metal contamination.

    Science.gov (United States)

    Li, Xiaoqi; Meng, Delong; Li, Juan; Yin, Huaqun; Liu, Hongwei; Liu, Xueduan; Cheng, Cheng; Xiao, Yunhua; Liu, Zhenghua; Yan, Mingli

    2017-12-01

    Due to the persistence of metals in the ecosystem and their threat to all living organisms, effects of heavy metal on soil microbial communities were widely studied. However, little was known about the interactions among microorganisms in heavy metal-contaminated soils. In the present study, microbial communities in Non (CON), moderately (CL) and severely (CH) contaminated soils were investigated through high-throughput Illumina sequencing of 16s rRNA gene amplicons, and networks were constructed to show the interactions among microbes. Results showed that the microbial community composition was significantly, while the microbial diversity was not significantly affected by heavy metal contamination. Bacteria showed various response to heavy metals. Bacteria that positively correlated with Cd, e.g. Acidobacteria_Gp and Proteobacteria_thiobacillus, had more links between nodes and more positive interactions among microbes in CL- and CH-networks, while bacteria that negatively correlated with Cd, e.g. Longilinea, Gp2 and Gp4 had fewer network links and more negative interactions in CL and CH-networks. Unlike bacteria, members of the archaeal domain, i.e. phyla Crenarchaeota and Euryarchaeota, class Thermoprotei and order Thermoplasmatales showed only positive correlation with Cd and had more network interactions in CH-networks. The present study indicated that (i) the microbial community composition, as well as network interactions was shift to strengthen adaptability of microorganisms to heavy metal contamination, (ii) archaea were resistant to heavy metal contamination and may contribute to the adaption to heavy metals. It was proposed that the contribution might be achieved either by improving environment conditions or by cooperative interactions. Copyright © 2017 Elsevier Ltd. All rights reserved.

  14. The dynamics of molecular interactions and chemical reactions at metal surfaces: testing the foundations of theory.

    Science.gov (United States)

    Golibrzuch, Kai; Bartels, Nils; Auerbach, Daniel J; Wodtke, Alec M

    2015-04-01

    We review studies of molecular interactions and chemical reactions at metal surfaces, emphasizing progress toward a predictive theory of surface chemistry and catalysis. For chemistry at metal surfaces, a small number of central approximations are typically made: (a) the Born-Oppenheimer approximation of electronic adiabaticity, (b) the use of density functional theory at the generalized gradient approximation level, (c) the classical approximation for nuclear motion, and (d) various reduced-dimensionality approximations. Together, these approximations constitute a provisional model for surface chemical reactivity. We review work on some carefully studied examples of molecules interacting at metal surfaces that probe the validity of various aspects of the provisional model.

  15. Knocking on surfaces : interactions of hyperthermal particles with metal surfaces

    NARCIS (Netherlands)

    Ueta, Hirokazu

    2010-01-01

    The study of gas-surface interaction dynamics is important both for the fundamental knowledge it provides and also to aid the development of applications involving processes such as sputtering, plasma etching and heterogeneous catalysis. Elementary steps in the interactions, such as chemical

  16. Green synthesis of biogenic silver nanoparticles using Solanum tuberosum extract and their interaction with human serum albumin: Evidence of "corona" formation through a multi-spectroscopic and molecular docking analysis.

    Science.gov (United States)

    Ali, Mohd Sajid; Altaf, Mohammad; Al-Lohedan, Hamad A

    2017-08-01

    Biogenic silver nanoparticles (AgNPs) have been synthesized by using Solanum tuberosum (potato) extract (PE) as a reducing as well as stabilizing agent which is reasonably cheaper, non-toxic and easily available material. The green synthesis of silver nanoparticles has been carried out by very simple method and the nanoparticles were characterized by surface plasmon band as well as TEM measurements. The PE-AgNPs were highly dispersed in the solution and found to be spherical with around 10nm in size. Interaction of these nanoparticles was studied with plasma protein HSA by means of various spectroscopies, such as, UV-visible, fluorescence, DLS, CD and FTIR spectroscopies. The HSA was found to form the protein "corona" around the starch-capped PE-AgNPs. Absorption spectroscopy revealed that the interaction between HSA and PE-AgNPs resulted in the ground state complex formation. Due to the strong absorption of PE-AgNPs, the inner filter effect was corrected for the fluorescence data. PE-AgNPs were found to quench the fluorescence of HSA with a small blue shift attributed to the increase in the hydrophobicity near tryptophan residue due to the presence of amylopectin and amylose units in the starch. The value of n, Hill's constant, was found to be >1 which determines the existence of a cooperative binding between nanoparticle and albumin. Several parameters such as Stern-Volmer and binding constants in addition to the thermodynamic parameters have been analyzed and discussed which established that the complex formation has taken place via static quenching mechanism and the corona formation between albumin and PE-AgNPs was entropy driven process. Binding of biogenic PE-AgNPs to the HSA slightly affected the secondary structure of latter with a small decrease in α-helical contents resulting in the partial unfolding of the protein, though the structural motif remained the same. Molecular docking simulations revealed various possible binding modes between PE-AgNPs and

  17. INTERACTION OF IMPULSE ELECTROMAGNETIC FIELDS WITH SURFACES OF METAL SAMPLES

    Directory of Open Access Journals (Sweden)

    V. V. Pavliouchenko

    2006-01-01

    Full Text Available Measurements of maximum tangential component of magnetic intensity Hτm have been carried out in the paper. The measurements have been taken on the surface of metal samples according to time of single current pulse rise in the form of semi-sinusoid of a linear current wire. Measurements have been made with the purpose to determine a value of the component according to thickness of samples made of aluminium.Temporary resolution ranges of electric and magnetic properties and defects of sample continuity along the depth have been found.Empirical formulae of dependence Hτm on sample thickness have been derived and their relation with efficient depth penetration of magnetic field into metal has been found.

  18. Spectroscopic study on flavonoid–drug interactions: Competitive binding for human serum albumin between three flavonoid compounds and ticagrelor, a new antiplatelet drug

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Bing-Mi, E-mail: liubingmi@163.com [Department of Pharmacy, Liaoning University, Shenyang 110036 (China); Zhang, Jun [Department of Pharmacy, Liaoning University, Shenyang 110036 (China); Bai, Chong-Liang [Centre for Molecular Science and Engineering, Northeastern University, Shenyang 110819 (China); Wang, Xin; Qiu, Xin-Zhi; Wang, Xiao-Li; Ji, Hui [Department of Pharmacy, Liaoning University, Shenyang 110036 (China); Liu, Bin, E-mail: liubinzehao@163.com [Department of Pharmacy, Liaoning University, Shenyang 110036 (China)

    2015-12-15

    The effects of three kinds of flavonoids, quercetin, rutin and baicalin, on the binding of ticagrelor to human serum albumin (HSA) were systematically investigated using fluorescence, UV–vis absorption and circular dichroism (CD) spectroscopic techniques. The results indicated that ticagrelor strongly quenched the HSA fluorescence by the style of static quenching and non-radiation energy transferring as a result of the HSA–ticagrelor complex formation, while the presence of flavonoids could not change the quenching mechanism. Ticagrelor could spontaneously bind in site I on HSA with high affinity, and this binding process was mainly driven by both hydrophobic forces and hydrogen bonding. The significantly decreased binding affinity and the unchanged binding mode and distance between ticagrelor and HSA indicated that that flavonoids could compete against ticagrelor in site I, and baicalin was the most effective competitor. The conformation investigation of HSA further confirmed the flavonoid/ticagrelor competitive binding mechanism. - Highlights: • Ticagrelor could spontaneously bind in subdomain IIA (site I) on HSA with high affinity. • The presence of flavonoids could not change the quenching mechanism. • The presence of flavonoids significantly decreased the binding affinity of ticagrelor with HSA. • Flavonoids could compete against ticagrelor in site I. • Baicalin was the most effective competitor among the three flavonoids.

  19. Spectroscopic study on flavonoid–drug interactions: Competitive binding for human serum albumin between three flavonoid compounds and ticagrelor, a new antiplatelet drug

    International Nuclear Information System (INIS)

    Liu, Bing-Mi; Zhang, Jun; Bai, Chong-Liang; Wang, Xin; Qiu, Xin-Zhi; Wang, Xiao-Li; Ji, Hui; Liu, Bin

    2015-01-01

    The effects of three kinds of flavonoids, quercetin, rutin and baicalin, on the binding of ticagrelor to human serum albumin (HSA) were systematically investigated using fluorescence, UV–vis absorption and circular dichroism (CD) spectroscopic techniques. The results indicated that ticagrelor strongly quenched the HSA fluorescence by the style of static quenching and non-radiation energy transferring as a result of the HSA–ticagrelor complex formation, while the presence of flavonoids could not change the quenching mechanism. Ticagrelor could spontaneously bind in site I on HSA with high affinity, and this binding process was mainly driven by both hydrophobic forces and hydrogen bonding. The significantly decreased binding affinity and the unchanged binding mode and distance between ticagrelor and HSA indicated that that flavonoids could compete against ticagrelor in site I, and baicalin was the most effective competitor. The conformation investigation of HSA further confirmed the flavonoid/ticagrelor competitive binding mechanism. - Highlights: • Ticagrelor could spontaneously bind in subdomain IIA (site I) on HSA with high affinity. • The presence of flavonoids could not change the quenching mechanism. • The presence of flavonoids significantly decreased the binding affinity of ticagrelor with HSA. • Flavonoids could compete against ticagrelor in site I. • Baicalin was the most effective competitor among the three flavonoids.

  20. Interaction of benzo[a]pyrene diol epoxide isomers with human serum albumin: Site specific characterisation of adducts and associated kinetics

    Science.gov (United States)

    Motwani, Hitesh V.; Westberg, Emelie; Törnqvist, Margareta

    2016-11-01

    Carcinogenicity of benzo[a]pyrene {B[a]P, a polycyclic aromatic hydrocarbon (PAH)} involves DNA-modification by B[a]P diol epoxide (BPDE) metabolites. Adducts to serum albumin (SA) are not repaired, unlike DNA adducts, and therefore considered advantageous in assessment of in vivo dose of BPDEs. In the present work, kinetic experiments were performed in relation to the dose (i.e. concentration over time) of different BPDE isomers, where human SA (hSA) was incubated with respective BPDEs under physiological conditions. A liquid chromatography (LC) tandem mass spectrometry methodology was employed for characterising respective BPDE-adducts at histidine and lysine. This strategy allowed to structurally distinguish between the adducts from racemic anti- and syn-BPDE and between (+)- and (-)-anti-BPDE, which has not been attained earlier. The adduct levels quantified by LC-UV and the estimated rate of disappearance of BPDEs in presence of hSA gave an insight into the reactivity of the diol epoxides towards the N-sites on SA. The structure specific method and dosimetry described in this work could be used for accurate estimation of in vivo dose of the BPDEs following exposure to B[a]P, primarily in dose response studies of genotoxicity, e.g. in mice, to aid in quantitative risk assessment of PAHs.

  1. An alternate mode of binding of the polyphenol quercetin with serum albumins when complexed with Cu(II)

    International Nuclear Information System (INIS)

    Singha Roy, Atanu; Tripathy, Debi Ranjan; Ghosh, Arup Kumar; Dasgupta, Swagata

    2012-01-01

    Polyphenols find wide use as antioxidants, cancer chemopreventive agents and metal chelators. The latter activity has proved interesting in many aspects. We have probed the binding characteristics of the polyphenol quercetin–Cu(II) complex with human serum albumin (HSA) and bovine serum albumin (BSA). Fluorescence studies reveal that the quercetin–Cu(II) complex can quench the fluorescence of the serum albumins. The binding constant (K b ) values are of the order of 10 5 M −1 which increased with rise in temperature in case of HSA and BSA interacting with the quercetin–Cu(II) complex. Displacement studies reveal that both the ligands bind to site 1 (subdomain IIA) of the serum albumins. However, thermodynamic parameters calculated from temperature dependent studies indicated that the mode of interaction of the complexes with the proteins differs. Both ΔH° and ΔS° were positive for the interaction of the quercetin–Cu(II) complex with both proteins but the value of ΔH° was negative in case of the interaction of quercetin with the proteins. This implies that after chelation with metal ions, the polyphenol alters its mode of interaction which could have varying implications on its other physicochemical activities. - Research Highlights: ► Mode of binding of quercetin with SAs is altered after complexation with Cu(II). ► Hydrophobic forces play a key role in the binding of the copper complex with SAs. ► Negative ΔG° values indicate the spontaneity of the binding processes. ► Quercetin and its copper complex bind at the same site of the SAs.

  2. An alternate mode of binding of the polyphenol quercetin with serum albumins when complexed with Cu(II)

    Energy Technology Data Exchange (ETDEWEB)

    Singha Roy, Atanu; Tripathy, Debi Ranjan; Ghosh, Arup Kumar [Department of Chemistry, Indian Institute of Technology, Kharagpur 721302 (India); Dasgupta, Swagata, E-mail: swagata@chem.iitkgp.ernet.in [Department of Chemistry, Indian Institute of Technology, Kharagpur 721302 (India)

    2012-11-15

    Polyphenols find wide use as antioxidants, cancer chemopreventive agents and metal chelators. The latter activity has proved interesting in many aspects. We have probed the binding characteristics of the polyphenol quercetin-Cu(II) complex with human serum albumin (HSA) and bovine serum albumin (BSA). Fluorescence studies reveal that the quercetin-Cu(II) complex can quench the fluorescence of the serum albumins. The binding constant (K{sub b}) values are of the order of 10{sup 5} M{sup -1} which increased with rise in temperature in case of HSA and BSA interacting with the quercetin-Cu(II) complex. Displacement studies reveal that both the ligands bind to site 1 (subdomain IIA) of the serum albumins. However, thermodynamic parameters calculated from temperature dependent studies indicated that the mode of interaction of the complexes with the proteins differs. Both {Delta}H Degree-Sign and {Delta}S Degree-Sign were positive for the interaction of the quercetin-Cu(II) complex with both proteins but the value of {Delta}H Degree-Sign was negative in case of the interaction of quercetin with the proteins. This implies that after chelation with metal ions, the polyphenol alters its mode of interaction which could have varying implications on its other physicochemical activities. - Research Highlights: Black-Right-Pointing-Pointer Mode of binding of quercetin with SAs is altered after complexation with Cu(II). Black-Right-Pointing-Pointer Hydrophobic forces play a key role in the binding of the copper complex with SAs. Black-Right-Pointing-Pointer Negative {Delta}G Degree-Sign values indicate the spontaneity of the binding processes. Black-Right-Pointing-Pointer Quercetin and its copper complex bind at the same site of the SAs.

  3. Interaction of antihypertensive drug amiloride with metal ions in micellar medium using fluorescence spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Gujar, Varsha; Pundge, Vijaykumar; Ottoor, Divya, E-mail: divya@chem.unipune.ac.in

    2015-05-15

    Steady state and life time fluorescence spectroscopy have been employed to study the interaction of antihypertensive drug amiloride with biologically important metal ions i.e. Cu{sup 2+}, Fe{sup 2+}, Ni{sup 2+} and Zn{sup 2+} in various micellar media (anionic SDS (sodium dodecyl sulfate), nonionic TX-100 (triton X-100) and cationic CTAB (cetyl trimethyl ammonium bromide)). It was observed that fluorescence properties of drug remain unaltered in the absence of micellar media with increasing concentration of metal ions. However, addition of Cu{sup 2+}, Fe{sup 2+} and Ni{sup 2+} caused fluorescence quenching of amiloride in the presence of anionic micelle, SDS. Binding of drug with metal ions at the charged micellar interface could be the possible reason for this pH-dependent metal-mediated fluorescence quenching. There were no remarkable changes observed due to metal ions addition when drug was present in cationic and nonionic micellar medium. The binding constant and bimolecular quenching constant were evaluated and compared for the drug–metal complexes using Stern–Volmer equation and fluorescence lifetime values. - Highlights: • Interaction of amiloride with biologically important metal ions, Fe{sup 2+}, Cu{sup 2+}, Ni{sup 2+} and Zn{sup 2+}. • Monitoring the interaction in various micelle at different pH by fluorescence spectroscopy. • Micelles acts as receptor, amiloride as transducer and metal ions as analyte in the present system. • Interaction study provides pH dependent quenching and binding mechanism of drug with metal ions.

  4. Adsorption of albumin on prosthetic materials: implication for tribological behavior.

    Science.gov (United States)

    Serro, A P; Gispert, M P; Martins, M C L; Brogueira, P; Colaço, R; Saramago, B

    2006-09-01

    The orthopedic prosthesis used to substitute damaged natural joints are lubricated by a pseudosynovial fluid that contains biological macromolecules with potential boundary lubrication properties. Proteins are some of those macromolecules whose role in the lubrication process is not yet completely understood. In a previous work, we investigated the influence of the presence of albumin, the major synovial protein, upon the tribological behavior of three of the most used pairs of artificial joint materials: ultra high molecular weight polyethylene (UHMWPE) against counterfaces of alumina, CoCrMo alloy, and 316L stainless steel. Albumin was found to cause a significant decrease in the friction coefficient when the counterfaces were metallic because transfer of UHMWPE was avoided, but this effect was much weaker in the case of alumina. The objective of the present work was to look for an explanation for these differences in tribological behavior in terms of albumin adsorption. With this goal, studies on adsorption of bovine serum albumin (BSA) on the counterface materials, from a biological model fluid (Hanks' balanced salt solution), were carried out using radiolabeled albumin ((125)I-BSA), X-ray photoelectron spectroscopy, and atomic force microscopy. The conclusion from all techniques is that the driving force for albumin adsorption is higher on the metals than on alumina. These results confirm that the greater the amount of protein adsorbed on the counterface, the more efficient is the protection against the transfer of polymeric film to the counterface.

  5. Binding and Anticancer Properties of Plumbagin with Human Serum Albumin.

    Science.gov (United States)

    Gou, Yi; Zhang, Yao; Qi, Jinxu; Kong, Linlin; Zhou, Zuping; Liang, Shichu; Yang, Feng; Liang, Hong

    2015-09-01

    Plumbagin has received extensive attention as a promising anticancer drug. Therefore, we investigated the binding and anticancer properties of plumbagin with human serum albumin. Fluorescence results demonstrated that plumbagin interacts with human serum albumin, although its binding affinity may be affected to various extents by different compounds. The human serum albumin-plumbagin complex structure revealed that plumbagin binds to the hydrophobic cavity in the IIA subdomain of human serum albumin through hydrogen bonding and hydrophobic interactions. The plumbagin-human serum albumin complex enhances cytotoxicity by 2- to 3-fold particularly in cancer cells but has no effect on normal cells in vitro. Compared with the unbound drug, the human serum albumin-plumbagin complex promotes HeLa cell apoptosis and has a stronger capacity for cell cycle arrest at the G2/M phase of HeLa cells. In conclusion, this study contributes to the rational design and development of plumbagin-based drugs and a drug-human serum albumin delivery system. © 2014 John Wiley & Sons A/S.

  6. The Thermodynamics of Proteins Interactions with Essential First Raw Transition Metals

    Science.gov (United States)

    Bou-Abdallah, Fadi; Giffune, Thomas

    2015-01-01

    Background The binding of metal ions to proteins is a crucial process required for their catalytic activity, structural stability and/or functional regulation. Isothermal titration calorimetry provides a wealth of fundamental information which when combined with structural data allow for a much deeper understanding of the underlying molecular mechanism. Scope of review A rigorous understanding of any molecular interaction requires in part an in-depth quantification of its thermodynamic properties. Here, we provide an overview of recent studies that have used ITC to quantify the interaction of essential first raw transition metals with relevant proteins and highlight major findings from these thermodynamic studies. General significance The thermodynamic characterization of metal ions-proteins interactions is one important step to understanding the role that metal ions play in living systems. Such characterization has important implications not only to elucidating proteins’ structure-function relationships and biological properties but also in the biotechnology sector, medicine and drug design particularly since a number of metal ions are involved in several neurodegenerative diseases. Major conclusions Isothermal titration calorimetry measurements can provide complete thermodynamic profiles of any molecular interaction through the simultaneous determination of the reaction binding stoichiometry, binding affinity as well as the enthalpic and entropic contributions to the free energy change thus enabling a more in-depth understanding of the nature of these interactions. PMID:26569121

  7. The thermodynamics of protein interactions with essential first row transition metals.

    Science.gov (United States)

    Bou-Abdallah, Fadi; Giffune, Thomas R

    2016-05-01

    The binding of metal ions to proteins is a crucial process required for their catalytic activity, structural stability and/or functional regulation. Isothermal titration calorimetry provides a wealth of fundamental information which when combined with structural data allow for a much deeper understanding of the underlying molecular mechanism. A rigorous understanding of any molecular interaction requires in part an in-depth quantification of its thermodynamic properties. Here, we provide an overview of recent studies that have used ITC to quantify the interaction of essential first row transition metals with relevant proteins and highlight major findings from these thermodynamic studies. The thermodynamic characterization of metal ion-protein interactions is one important step to understanding the role that metal ions play in living systems. Such characterization has important implications not only to elucidating proteins' structure-function relationships and biological properties but also in the biotechnology sector, medicine and drug design particularly since a number of metal ions are involved in several neurodegenerative diseases. Isothermal titration calorimetry measurements can provide complete thermodynamic profiles of any molecular interaction through the simultaneous determination of the reaction binding stoichiometry, binding affinity as well as the enthalpic and entropic contributions to the free energy change thus enabling a more in-depth understanding of the nature of these interactions. Copyright © 2015 Elsevier B.V. All rights reserved.

  8. Resonance Fluorescence of Many Interacting Adatoms at a Metal Surface.

    Science.gov (United States)

    1983-06-01

    of the system, one can write a total Hamiltonian as HA + B + AB + HAA HABA + HAR HBB + HAF (7) HA and H are the unperturbed Hamiltonians for the...adatom-plasmon interaction may be further broadened via HAA and HABA in which the collisional effects may be significant for a high-coverage system and/or

  9. Interaction between Nafion ionomer and noble metal catalyst for PEMFCs

    DEFF Research Database (Denmark)

    Andersen, Shuang Ma

    The implement of polymer impregnation in electrode structure (catalyst layer) decreasing the noble metal catalyst loading by a factor of ten , , is one of the essential mile stones in the evolution of Proton Exchange Membrane Fuel Cells’ development among the application of catalyst support...... and electrode deposition etc. In fuel cell reactions, both electrons and protons are involved. Impregnation of Nafion ionomer in catalyst layer effectively increases the proton-electron contact, enlarge the reaction zone, extend the reaction from the surface to the entire electrode. Therefore, the entire...... catalyst layer conducts both electrons and protons so that catalyst utilization in the layer is improved dramatically. The catalyst layer will in turn generate and sustain a higher current density. One of the generally adapted methods to impregnate Nafion into the catalyst layer is to mix the catalysts...

  10. Ecological interactions between metals and microbes that impact bioremediation

    Energy Technology Data Exchange (ETDEWEB)

    Allan Konopka; Cindy Nakatsu

    2004-03-17

    Distinct microbial communities had been found in contaminated soils that varied in their concentrations of Pb, Cr and aromatic compounds. It is difficult to distinguish between their effects as their presence is highly correlated. Microcosms were constructed in which either Pb{sup +2} or CrO{sub 4}{sup -2} was added at levels that produced acute modest or severe acute effects (50 or 90% reduction). We previously reported on changes in microbial activity and broad patterns of Bacterial community composition. These results showed that addition of an organic energy source selected for a relatively small number of phylotypes and the addition of Pb or Cr(VI) modulated the community response. We sequenced dominant phylotypes from microcosms amended with xylene and Cr(VI) and from those with the simple addition of glucose only. In both cases, the dominant selected phylotypes were diverse. We found a number of distinct Arthrobacter strains, as well as several Pseudomonas spp. In addition, the high GC-content bands belonged to members of the genera Nocardioides and Rhodococcus. The focus of amended microcosm work has now shifted to anaerobic processes. The reduction of Cr(VI) to Cr(III) as a detoxification mechanism is of greater interest, as is the specific role of particular physiological groups of anaerobes in mediating Cr(VI) detoxification. The correlation between microbial activity, community structure, and metal level has been analyzed on 150 mg of soil collected at spatial scales <1, 5, 15 and 50 cm. There was no correlation between metal content and activity level. Soils <1 cm apart could differ in activity 10-fold and extractable Pb and Cr 7-fold. Therefore, we turned to geostatistical analysis. There was spatial periodicity which is likely to reflect the heterogeneous distribution of active microbes and metal contaminants. Variograms indicated that the range of spatial dependence was up to 20 cm. To visualize the spatial relationships between the primary variate

  11. Evaluation of the interaction mechanisms between red muds and heavy metals.

    Science.gov (United States)

    Santona, Laura; Castaldi, Paola; Melis, Pietro

    2006-08-21

    This paper investigated the heavy metal adsorption of non-treated (RM(nt)) and acid-treated red muds (RM(a)), bauxite ore processing waste, in order to evaluate how efficient they are in reducing metal solubility and bioavaliability in polluted soils. Red mud samples were artificially polluted with solutions containing increasing concentrations of Pb, Cd and Zn. Cancrinite and hematite were the main phases of the red muds, and were also the components which adsorbed most heavy metals. The results showed that the RM(nt) adsorption capacity for the three heavy metals was Zn> or =Pb>Cd. Acid treatment with HCl decreased the red mud's capacity to adsorb the heavy metals by 30%. In order to study the different heavy metal-RM interaction mechanisms, all samples after artificial contamination were treated with solutions with gradually increasing extraction capacity. H(2)O and Ca(NO(3))(2) treatments only extracted very low concentrations of Pb, Cd and Zn, while EDTA treatment extracted the most adsorbed heavy metals from the sorbent particles. In particular the water-soluble and exchangeable metal fractions were higher in the RM(a) than they were in the RM(nt), while the concentrations of Pb, Cd and Zn extracted with EDTA were lower. The results showed that red muds can be used successfully to reduce the solubility and bioavailability of heavy metals in polluted soils.

  12. A Novel Albumin-Based Tissue Scaffold for Autogenic Tissue Engineering Applications

    OpenAIRE

    Li, Pei-Shan; -Liang Lee, I.; Yu, Wei-Lin; Sun, Jui-Sheng; Jane, Wann-Neng; Shen, Hsin-Hsin

    2014-01-01

    Tissue scaffolds provide a framework for living tissue regeneration. However, traditional tissue scaffolds are exogenous, composed of metals, ceramics, polymers, and animal tissues, and have a defined biocompatibility and application. This study presents a new method for obtaining a tissue scaffold from blood albumin, the major protein in mammalian blood. Human, bovine, and porcine albumin was polymerised into albumin polymers by microbial transglutaminase and was then cast by freeze-drying-b...

  13. Synchrotron X-ray Investigations of Mineral-Microbe-Metal Interactions

    International Nuclear Information System (INIS)

    Kemner, Kenneth M.; O'Loughlin, Edward J.; Kelly, Shelly D.; Boyanov, Maxim I.

    2005-01-01

    Interactions between microbes and minerals can play an important role in metal transformations (i.e. changes to an element's valence state, coordination chemistry, or both), which can ultimately affect that element's mobility. Mineralogy affects microbial metabolism and ecology in a system; microbes, in turn, can affect the system's mineralogy. Increasingly, synchrotron-based X-ray experiments are in routine use for determining an element's valence state and coordination chemistry, as well as for examining the role of microbes in metal transformations.

  14. Mechanisms of Heavy Metal Sequestration in Soils: Plant-Microbe Interactions and Organic Matter Aging

    Energy Technology Data Exchange (ETDEWEB)

    Teresa W.-M. Fan; Richard M. Higashi; David Crowley; Andrew N. Lane: Teresa A. Cassel; Peter G. Green

    2004-12-31

    For stabilization of heavy metals at contaminated sites, the three way interaction among soil organic matter (OM)-microbes-plants, and their effect on heavy metal binding is critically important for long-term sustainability, a factor that is poorly understood at the molecular level. Using a soil aging system, the humification of plant matter such as wheat straw was probed along with the effect on microbial community on soil from the former McClellan Air Force Base.

  15. Interaction of lactic acid bacteria with metal ions: opportunities for improving food safety and quality.

    Science.gov (United States)

    Mrvčić, Jasna; Stanzer, Damir; Solić, Ema; Stehlik-Tomas, Vesna

    2012-09-01

    Certain species of lactic acid bacteria (LAB), as well as other microorganisms, can bind metal ions to their cells surface or transport and store them inside the cell. Due to this fact, over the past few years interactions of metal ions with LAB have been intensively investigated in order to develop the usage of these bacteria in new biotechnology processes in addition to their health and probiotic aspects. Preliminary studies in model aqueous solutions yielded LAB with high absorption potential for toxic and essential metal ions, which can be used for improving food safety and quality. This paper provides an overview of results obtained by LAB application in toxic metal ions removing from drinking water, food and human body, as well as production of functional foods and nutraceutics. The biosorption abilities of LAB towards metal ions are emphasized. The binding mechanisms, as well as the parameters influencing the passive and active uptake are analyzed.

  16. Adsorbate-mediated strong metal-support interactions in oxide-supported Rh catalysts.

    Science.gov (United States)

    Matsubu, John C; Zhang, Shuyi; DeRita, Leo; Marinkovic, Nebojsa S; Chen, Jingguang G; Graham, George W; Pan, Xiaoqing; Christopher, Phillip

    2017-02-01

    The optimization of supported metal catalysts predominantly focuses on engineering the metal site, for which physical insights based on extensive theoretical and experimental contributions have enabled the rational design of active sites. Although it is well known that supports can influence the catalytic properties of metals, insights into how metal-support interactions can be exploited to optimize metal active-site properties are lacking. Here we utilize in situ spectroscopy and microscopy to identify and characterize a support effect in oxide-supported heterogeneous Rh catalysts. This effect is characterized by strongly bound adsorbates (HCO x ) on reducible oxide supports (TiO 2 and Nb 2 O 5 ) that induce oxygen-vacancy formation in the support and cause HCO x -functionalized encapsulation of Rh nanoparticles by the support. The encapsulation layer is permeable to reactants, stable under the reaction conditions and strongly influences the catalytic properties of Rh, which enables rational and dynamic tuning of CO 2 -reduction selectivity.

  17. Characterization of Metal Ion ­ Colloid Interaction: Impact On Colloid-facilitated Transport

    Science.gov (United States)

    Specht, C. H.; Schmitt, D.; Kaulisch, E.-M.; Frimmel, F. H.

    It is generally accepted, that metal transport in natural aquatic systems strongly de- pends on the metal binding form. Besides complex formation with well defined inor- ganic and organic ligands, the interaction with colloidal particles and soil material is one of the most important reactions of metal ions in aquatic systems. Mobile colloids compete with the stationary soil matrix for binding of metal ions and might facili- tate their transport. Important representatives for mineral and organic colloids are clay minerals and natural organic matter (NOM), respectively. In this work, the interaction of metal ions with clay minerals and NOM is characterized by coupling of asymmetric flow field-flow fractionation AF4 to inductively coupled plasma ­ mass spectrometry (ICPMS). A method for separating mineral from organic colloids is presented, which allows to quantify the amount of metals being bound to either colloid. For different metal ions (Cu, Zn, Pb, Pt) and a metalloid (As) a different extent of binding to either colloid was found.The information obtained from the AF4-ICPMS measurements was useful for the understanding of the observations from column experiments which were conducted to quantify the colloid-facilitated metal transport. In column experiments, the transport of the mineral colloids itself and the influence of NOM onto the colloid transport were investigated. Furthermore, the dependance of colloid transport from the ionic strength and the pH value was elucidated. In order to get information about the co-transport of metal ions by organic and mineral colloids, metal ions were adsorbed onto the colloidal material and a distribution coef- ficient of the metal ions between the colloidal phase and the solution was determined. The colloidal suspension containing both, "free" and adsorbed metal ions were then injected onto the column. The direct metal breakthrough caused by colloidal trans- port was detected at the column outlet. The results clearly

  18. Metal-insulator transition in SrIrO3 with strong spin-orbit interaction.

    Science.gov (United States)

    Wu, Fei-Xiang; Zhou, Jian; Zhang, L Y; Chen, Y B; Zhang, Shan-Tao; Gu, Zheng-Bin; Yao, Shu-Hua; Chen, Yan-Feng

    2013-03-27

    The thickness-dependent metal-insulator transition is observed in meta-stable orthorhombic SrIrO3 thin films synthesized by pulsed laser deposition. SrIrO3 films with thicknesses less than 3 nm demonstrate insulating behaviour, whereas those thicker than 4 nm exhibit metallic conductivity at high temperature, and insulating-like behaviour at low temperature. Weak/Anderson localization is mainly responsible for the observed thickness-dependent metal-insulator transition in SrIrO3 films. Temperature-dependent resistance fitting shows that electrical-conductivity carriers are mainly scattered by the electron-boson interaction rather than the electron-electron interaction. Analysis of the magneto-conductance proves that the spin-orbit interaction plays a crucial role in the magneto-conductance property of SrIrO3.

  19. Sex-specific Profiles of Blood Metal Levels Associated with Metal–Iron Interactions

    Directory of Open Access Journals (Sweden)

    Byung-Kook Lee

    2014-09-01

    Full Text Available The mechanisms by which iron is absorbed are similar to those of divalent metals, particularly manganese, lead, and cadmium. These metals, however, show different toxicokinetics in relation to menarche or menopause, although their interaction with iron is the same. This review focuses on the kinetics of these three toxic metals (manganese, lead, and cadmium in relation to menarche, pregnancy, and menopause. The iron–manganese interaction is the major factor determining sex-specific differences in blood manganese levels throughout the whole life cycle. The effects of estrogen overshadow the association between iron deficiency and increased blood lead concentrations, explaining why women, despite having lower ferritin concentrations, have lower blood lead concentrations than men. Iron deficiency is associated with elevated cadmium levels in premenopausal women, but not in postmenopausal women or men; these findings indicate that sex-specific differences in cadmium levels at older ages are not due to iron–cadmium interactions, and that further studies are required to identify the source of these differences. In summary, the potential causes of sex-specific differences in the blood levels of manganese, lead, and cadmium differ from each other, although all these three metals are associated with iron deficiency. Therefore, other factors such as estrogen effects, or absorption rate as well as iron deficiency, should be considered when addressing environmental exposure to toxic metals and sex-specific differences in the blood levels of these metals.

  20. Interaction of beam and coated metals at high power continuous irradiation

    Science.gov (United States)

    Kim, Yong Hyeon; Baek, Won-Kye; Yoh, Jack J.

    2011-07-01

    The beam-matter interaction with various coating effects has received continued attention in the high power laser community. Previous works suggest that coatings promote target damage when compared to beaming on uncoated surface. Three types of paint coatings (acrylic urethane, silicone alkyd and stealth blend) and a water coat on metals (Al, Ti and STS) are irradiated with a CO 2 laser. Both strain and temperature measurements are provided for assessing the instantaneous response characteristics of each coating on different metals. A selective combination of surface coats with metals has been proven to be effective in either preventing or enhancing damage, both thermal and mechanical, associated with focused beaming on a target.

  1. Interaction of Model Inhibitor Compounds with Minimalist Cluster Representations of Hydroxyl Terminated Metal Oxide Surfaces

    Directory of Open Access Journals (Sweden)

    Christopher D. Taylor

    2018-01-01

    Full Text Available The computational modeling of corrosion inhibitors at the level of molecular interactions has been pursued for decades, and recent developments are allowing increasingly realistic models to be developed for inhibitor–inhibitor, inhibitor–solvent and inhibitor–metal interactions. At the same time, there remains a need for simplistic models to be used for the purpose of screening molecules for proposed inhibitor performance. Herein, we apply a reductionist model for metal surfaces consisting of a metal cation with hydroxide ligands and use quantum chemical modeling to approximate the free energy of adsorption for several imidazoline class candidate corrosion inhibitors. The approximation is made using the binding energy and the partition coefficient. As in some previous work, we consider different methods for incorporating solvent and reference systems for the partition coefficient. We compare the findings from this short study with some previous theoretical work on similar systems. The binding energies for the inhibitors to the metal hydroxide clusters are found to be intermediate to the binding energies calculated in other work for bare metal vs. metal oxide surfaces. The method is applied to copper, iron, aluminum and nickel metal systems.

  2. Interaction of mobile phones with superficial passive metallic implants

    International Nuclear Information System (INIS)

    Virtanen, H; Huttunen, J; Toropainen, A; Lappalainen, R

    2005-01-01

    The dosimetry of exposure to radiofrequency (RF) electromagnetic (EM) fields of mobile phones is generally based on the specific absorption rate (SAR, W kg -1 ), which is the electromagnetic energy absorbed in the tissues per unit mass and time. In this study, numerical methods and modelling were used to estimate the effect of a passive, metallic (conducting) superficial implant on a mobile phone EM field and especially its absorption in tissues in the near field. Two basic implant models were studied: metallic pins and rings in the surface layers of the human body near the mobile phone. The aim was to find out 'the worst case scenario' with respect to energy absorption by varying different parameters such as implant location, orientation, size and adjacent tissues. Modelling and electromagnetic field calculations were carried out using commercial SEMCAD software based on the FDTD (finite difference time domain) method. The mobile phone was a 900 MHz or 1800 MHz generic phone with a quarter wave monopole antenna. A cylindrical tissue phantom models different curved sections of the human body such as limbs or a head. All the parameters studied (implant size, orientation, location, adjacent tissues and signal frequency) had a major effect on the SAR distribution and in certain cases high local EM fields arose near the implant. The SAR values increased most when the implant was on the skin and had a resonance length or diameter, i.e. about a third of the wavelength in tissues. The local peak SAR values increased even by a factor of 400-700 due to a pin or a ring. These highest values were reached in a limited volume close to the implant surface in almost all the studied cases. In contrast, without the implant the highest SAR values were generally reached on the skin surface. Mass averaged SAR 1g and SAR 10g values increased due to the implant even by a factor of 3 and 2, respectively. However, at typical power levels of mobile phones the enhancement is unlikely to be

  3. The interaction of trace heavy metal with lipid monolayer in the sea surface microlayer.

    Science.gov (United States)

    Li, Siyang; Du, Lin; Tsona, Narcisse T; Wang, Wenxing

    2018-04-01

    Lipid molecules and trace heavy metals are enriched in sea surface microlayer and can be transferred into the sea spray aerosol. To better understand their impact on marine aerosol generation and evolution, we investigated the interaction of trace heavy metals including Fe 3+ , Pb 2+ , Zn 2+ , Cu 2+ , Ni 2+ , Cr 3+ , Cd 2+ , and Co 2+ , with dipalmitoylphosphatidylcholine (DPPC) monolayers at the air-water interface. Phase behavior of the DPPC monolayer on heavy metal solutions was probed with surface pressure-area (π-A) isotherms. The conformation order and orientation of DPPC alkyl chains were characterized by infrared reflection-absorption spectroscopy (IRRAS). The π-A isotherms show that Zn 2+ and Fe 3+ strongly interact with DPPC molecules, and induce condensation of the monolayers in a concentration-dependent manner. IRRAS spectra show that the formation of cation-DPPC complex gives rise to conformational changes and immobilization of the headgroups. The current results suggest that the enrichment of Zn 2+ in sea spray aerosols is due to strong binding to the DPPC film. The interaction of Fe 3+ with DPPC monolayers can significantly influence their surface organizations through the formation of lipid-coated particles. These results suggest that the sea surface microlayer is capable of accumulating much higher amounts of these metals than the subsurface water. The organic and metal pollutants may transfer into the atmosphere by this interaction. Copyright © 2017 Elsevier Ltd. All rights reserved.

  4. Interaction of laser radiation with metal island films

    Science.gov (United States)

    Benditskii, A. A.; Viduta, L. V.; Ostranitsa, A. P.; Tomchuk, P. M.; Iakovlev, V. A.

    1986-08-01

    The emission phenomena arising during the interaction of pulsed laser emission with island films are examined with reference to experimental results obtained for island films of gold irradiated by a CO2 laser at a wavelength of 10.6 microns. Well reproducible emission pulses that are also accompanied by light pulses are produced at intensities less than 10 to the 5th W/sq cm, with the film structure remaining unchanged. The maximum energy of the electrons emitted under the effect of laser radiation is estimated at 3 eV; the work function is 2.1 eV.

  5. Electron confinement in thin metal films. Structure, morphology and interactions

    Energy Technology Data Exchange (ETDEWEB)

    Dil, J.H.

    2006-05-15

    This thesis investigates the interplay between reduced dimensionality, electronic structure, and interface effects in ultrathin metal layers (Pb, In, Al) on a variety of substrates (Si, Cu, graphite). These layers can be grown with such a perfection that electron confinement in the direction normal to the film leads to the occurrence of quantum well states in their valence bands. These quantum well states are studied in detail, and their behaviour with film thickness, on different substrates, and other parameters of growth are used here to characterise a variety of physical properties of such nanoscale systems. The sections of the thesis deal with a determination of quantum well state energies for a large data set on different systems, the interplay between film morphology and electronic structure, and the influence of substrate electronic structure on their band shape; finally, new ground is broken by demonstrating electron localization and correlation effects, and the possibility to measure the influence of electron-phonon coupling in bulk bands. (orig.)

  6. Non-covalent interaction between dietary stilbenoids and human serum albumin: Structure-affinity relationship, and its influence on the stability, free radical scavenging activity and cell uptake of stilbenoids.

    Science.gov (United States)

    Cao, Hui; Jia, Xueping; Shi, Jian; Xiao, Jianbo; Chen, Xiaoqing

    2016-07-01

    Dietary stilbenoids are associated with many benefits for human health, which depend on their bioavailability and bioaccessibility. The stilbenoid-human serum albumin (HSA) interactions are investigated to explore the structure-affinity relationship and influence on the stability, free radical scavenging activity and cell uptake of stilbenoids. The structure-affinity relationship of the stilbenoids-HSA interaction was found as: (1) the methoxylation enhanced the affinity, (2) an additional hydroxyl group increases the affinity and (3) the glycosylation significantly weakened the affinity. HSA obviously masked the free radical scavenging potential of stilbenoids. The stabilities of stilbenoids in different medium were determined as: HSA solution>human plasma>Dulbecco's modified Eagle's medium. It appears that the milk enhanced the cell uptake of stilbenoids with multi-hydroxyl groups and weakened the cell uptake of stilbenoids with methoxyl group on EA.hy 926 endothelial cells. The stilbenoids are hardly absorbed by human umbilical vein endothelial cells in the presence of milk. Copyright © 2016 Elsevier Ltd. All rights reserved.

  7. Long-range interactions between excited helium and alkali-metal atoms

    KAUST Repository

    Zhang, J.-Y.

    2012-12-03

    The dispersion coefficients for the long-range interaction of the first four excited states of He, i.e., He(2 1,3S) and He(2 1,3P), with the low-lying states of the alkali-metal atoms Li, Na, K, and Rb are calculated by summing over the reduced matrix elements of the multipole transition operators. For the interaction between He and Li the uncertainty of the calculations is 0.1–0.5%. For interactions with other alkali-metal atoms the uncertainty is 1–3% in the coefficient C5, 1–5% in the coefficient C6, and 1–10% in the coefficients C8 and C10. The dispersion coefficients Cn for the interaction of He(2 1,3S) and He(2 1,3P) with the ground-state alkali-metal atoms and for the interaction of He(2 1,3S) with the alkali-metal atoms in their first 2P states are presented in this Brief Report. The coefficients for other pairs of atomic states are listed in the Supplemental Material.

  8. Purification of monoclonal antibodies, IgG1, from cell culture supernatant by use of metal chelate convective interaction media monolithic columns.

    Science.gov (United States)

    Rajak, Poonam; Vijayalakshmi, M A; Jayaprakash, N S

    2012-12-01

    Monoclonal antibodies (MAbs) have diverse applications in diagnostics and therapeutics. The recent advancement in hybridoma technology for large-scale production of MAbs in bioreactors demands rapid and efficient purification methods. Conventional affinity purification systems have drawbacks of low flow rates and denaturation of antibodies owing to harsh elution conditions. Here, we attempted purification of MAbs by use of a high-throughput metal-chelate methacrylate monolithic system. Monolithic macroporous convective interaction media-iminodiacetate (CIM-IDA) disks immobilized with four different metal ions (Cu²⁺, Ni²⁺, Zn²⁺ and Co²⁺) were used and evaluated for purification of anti-human serum albumin IgG1 mouse MAbs from cell culture supernatant after precipitation with 50% ammonium sulfate. Elution with 10 mM imidazole in the equilibration buffer (25 mM MMA = MOPS (Morpholino propane sulfonic acid) + MES (Morpholino ethane sulfonic acid) + Acetate + 0.5 M NaCl, pH 7.4) resulted in a purification of 25.7 ± 2.9-fold and 32.5 ± 2.6-fold in experiments done using Zn²⁺ and Co²⁺ metal ions, respectively. The highest recovery of 85.4 ± 1.0% was obtained with a CIM-IDA-Zn(II) column. SDS-PAGE, ELISA and immuno-blot showed that the antibodies recovered were pure, with high antigen-binding efficiency. Thus, metal chelate CIM monoliths could be a potential alternative to conventional systems for fast and efficient purification of MAbs from the complex cell culture supernatant. Copyright © 2012 John Wiley & Sons, Ltd.

  9. Metal-Microbial Interactions in Toronto Sunnyside Beach: Impact on Water Quality and Public Health

    Science.gov (United States)

    Plach, J. M.; Elliott, A.; Warren, L. A.

    2009-05-01

    Assessing recreational water quality requires a fundamental understanding of metal-microbial interactions and the key biogeochemical processes occurring in urban public beaches. Metals play an important role in the distribution and virulence (e.g. resistance) of microorganisms in water systems. In turn, microorganisms have a significant influence on metal cycling, thus affecting metal mobility, bioavailability and toxicity in the aquatic environment. Bacteria adhere to floc, small suspended mineral-bacterial aggregates, in aquatic systems resulting in high-density floc-associated bacterial biofilm communities. These nanoparticulate bacterial microhabitats are important environmental sinks for metals and potential reservoirs for antibiotic resistant and pathogenic bacteria. The objectives of this study are to identify and quantify (1) metal distributions among suspended floc, bed sediment and water-column aqueous compartments (2) important biogeochemical processes influencing metal cycling and (3) linkages between floc metals and the occurrence of floc associated antibiotic resistant bacteria and pathogens across a series of variably contaminated aquatic systems. Results of this project will provide new diagnostic indicators of pathogens in recreational water systems and aid in the development of public health policies to improve water quality and reduce water borne infectious disease. Here, results will be presented assessing the metal and microbial community dynamics in samples collected from Toronto's Sunnyside Beach (May 13 and August 20), an urban public beach on Lake Ontario. Water column, floc and bed sediments near and offshore were analyzed for physico-chemical characteristics and metal concentrations. Floc were imaged using DAPI and FISH to assess microbial community structure. Results to date, characterizing the linkages amongst bacteria, metal contaminant concentrations and sediment partitioning and system physico-chemical conditions will be discussed.

  10. Thyroid albumin originates from blood

    NARCIS (Netherlands)

    de Vijlder, J. J.; Veenboer, G. J.; van Dijk, J. E.

    1992-01-01

    Iodoalbumin has been found in the goiter of Dutch goats with a thyroglobulin synthesis defect. Immunohistochemical studies showed that in the goiter the percentage of follicles containing albumin was higher than that in normal thyroid glands. In the albumin-containing follicles of normal and

  11. DETERMINATION OF SERUM ALBUMIN WITH ...

    African Journals Online (AJOL)

    The reaction of tribromoarsenazo(TB-ASA) with serum albumin in the presence of emulgent OP was studied by spectrophotometry. In a Britton-Robinson buffer solution at pH 2.9, tribromoarsenazo and bovine serum albumin can immediately form a red compound in the presence of emulgent OP with a maximum absorption ...

  12. Reactivity of the Bacteria-Water Interface: Linking Nutrient Availability to Bacteria-Metal Interactions

    Science.gov (United States)

    Fowle, D. A.; Daughney, C. J.; Riley, J. L.

    2002-12-01

    Identifying and quantifying the controls on metal mobilities in geologic systems is critical in order to understand processes such as global element cycling, metal transport in near-surface water-rock systems, sedimentary diagenesis, and mineral formation. Bacteria are ubiquitous in near-surface water-rock systems, and numerous laboratory and field studies have demonstrated that bacteria can facilitate the formation and dissolution of minerals, and enhance or inhibit contaminant transport. However, despite the growing evidence that bacteria play a key role in many geologic processes in low temperature systems, our understanding of the influence of the local nutrient dynamics of the system of interest on bacteria-metal interactions is limited. Here we present data demonstrating the effectiveness of coupling laboratory experiments with geochemical modeling to isolate the effect of nutrient availability on bacterially mediated proton and metal adsorption reactions. Experimental studies of metal-bacteria interactions were conducted in batch reactors as a function of pH, and solid-solute interactions after growth in a variety of defined and undefined media. Media nutrient composition (C,N,P) was quantified before and after harvesting the cells. Surface complexation models (SCM) for the adsorption reactions were developed by combining sorption data with the results of acid-base titrations, and in some cases zeta potential titrations of the bacterial surface. Our results indicate a clear change in both buffering potential and metal binding capacity of the cell walls of Bacillus subtilis as a function of initial media conditions. Combining current studies with our past studies on the effects of growth phase and others work on temperature dependence on metal adsorption we hope to develop a holistic surface complexation model for quantifying bacterial effects on metal mass transfer in many geologic systems.

  13. Interparticle interactions and structure in nonideal solutions of human serum albumin studied by small-angle neutron scattering and Monte Carlo simulation

    DEFF Research Database (Denmark)

    Sjöberg, B.; Mortensen, K.

    1994-01-01

    Moderately or highly concentrated nonideal solutions of macromolecules are very important systems e.g. in biology and in many technical processes. In this work we have used the small-angle neutron scattering technique (SANS) to study the interactions and interparticle structure in solutions......(r). The advantage of using the Monte Carlo method is that completely general models for the particle shape and the interactions can be considered. It is found that the SANS data can be explained by a model where the shape of the HSA molecule is approximated by an ellipsoid of revolution with semiaxes a = 6.8 nm...

  14. Solvent-dependent binding interactions of the organophosphate pesticide, chlorpyrifos (CPF), and its metabolite, 3,5,6-trichloro-2-pyridinol (TCPy), with Bovine Serum Albumin (BSA): A comparative fluorescence quenching analysis.

    Science.gov (United States)

    Dahiya, Vandana; Chaubey, Bhawna; Dhaharwal, Ashok K; Pal, Samanwita

    2017-06-01

    Analysis of the interaction of pesticides and their metabolites with the cellular proteins has drawn considerable attention in past several years to understand the effect of pesticides on environment and mankind. In this study, we have investigated the binding interaction of Bovine Serum Albumin (BSA) with a widely used organophosphorous insecticide chlorpyrifos (CPF), and its stable metabolite, 3,5,6-trichloro-2-pyridinol (TCPy) to provide a comparative analysis of the two molecules by employing various spectroscopic techniques viz., UV-vis absorption, Circular Dichroism (CD), and Fluorescence spectroscopy. The fluorescence quenching studies of BSA emission in two different solvents viz., water and methanol in presence of CPF and TCPy have led to the revelation of several interesting facts about the pesticide-protein interaction. It has been found that both the molecules cause static quenching of BSA emission as seen from the Stern-Volmer constant (K sv ) irrespective of the solvent used for the analysis. While TCPy is a stronger quencher in water, it exhibits comparable quenching capacity with CPF in methanol. The solvent dependent differential binding interaction of the two molecules finally indicates possibility of diverse bio-distribution of the pesticides within human body. The UV-vis and CD spectra of BSA in presence of the test molecules have unravelled that the molecules formed ground state complex that are highly reversible in nature and have minimal effect on the protein secondary structure. Furthermore it is also understood that structural changes of BSA in presence of CPF is significantly higher compared to that in presence of TCPY. Copyright © 2017 Elsevier Inc. All rights reserved.

  15. Applications of ion implantation for modifying the interactions between metals and hydrogen gas

    Science.gov (United States)

    Musket, R. G.

    1989-04-01

    Ion implantations into metals have been shown recently to either reduce or enhance interactions with gaseous hydrogen. Published studies concerned with modifications of these interactions are reviewed and discussed in terms of the mechanisms postulated to explain the observed changes. The interactions are hydrogenation, hydrogen permeation, and hydrogen embrittlement. In particular, the results of the reviewed studies are (a) uranium hydriding suppressed by implantation of oxygen and carbon, (b) hydrogen gettered in iron and nickel using implantation of titanium, (c) hydriding of titanium catalyzed by implanted palladium, (d) tritium permeation of 304L stainless steel reduced using selective oxidation of implanted aluminum, and (e) hydrogen attack of a low-alloy steel accelerated by implantation of helium. These studies revealed ion implantation to be an effective method for modifying the interactions of hydrogen gas with metals.

  16. Applications of ion implantation for modifying the interactions between metals and hydrogen gas

    International Nuclear Information System (INIS)

    Musket, R.G.

    1989-01-01

    Ion implantations into metals have been shown recently to either reduce or enhance interactions with gaseous hydrogen. Published studies concerned with modifications of these interactions are reviewed and discussed in terms of the mechanisms postulated to explain the observed changes. The interactions are hydrogenation, hydrogen permeation and hydrogen embrittlement. In particular, the results of the reviewed studies are 1. uranium hydriding suppressed by implantation of oxygen and carbon, 2. hydrogen gettered in iron and nickel using implantation of titanium, 3. hydriding of titanium catalyzed by implanted palladium, 4. tritium permeation of 304L stainless steel reduced using selective oxidation of implanted aluminum, and 5. hydrogen attack of a low-alloy steel accelerated by implantation of helium. These studies revealed ion implantation to be an effective method for modifying the interactions of hydrogen gas with metals. (orig.)

  17. Infrared Spectroscopy of Metal Ion Complexes: Models for Metal Ligand Interactions and Solvation

    Science.gov (United States)

    Duncan, Michael

    2006-03-01

    Weakly bound complexes of the form M^+-Lx (M=Fe, Ni, Co, etc.; L=CO2, C2H2, H2O, benzene, N2) are prepared in supersonic molecular beams by laser vaporization in a pulsed-nozzle cluster source. These species are mass analyzed and size-selected in a reflectron time-of-flight mass spectrometer. Clusters are photodissociated at infrared wavelengths with a Nd:YAG pumped infrared optical parametric oscillator/amplifier (OPO/OPA) laser or with a tunable infrared free-electron laser. M^+-(CO2)x complexes absorb near the free CO2 asymmetric stretch near 2349 cm-1 but with an interesting size dependent variation in the resonances. Small clusters have blue-shifted resonances, while larger complexes have additional bands due to surface CO2 molecules not attached to the metal. M^+(C2H2)n complexes absorb near the C-H stretches in acetylene, but resonances in metal complexes are red-shifted with repect to the isolated molecule. Ni^+ and Co^+ complexes with acetylene undergo intracluster cyclization reactions to form cyclobutadiene. Transition metal water complexes are studied in the O-H stretch region, and partial rotational structure can be measured. M^+(benzene) and M^+(benzene)2 ions (M=V, Ti, Al) represent half-sandwich and sandwich species, whose spectra are measured near the free benzene modes. These new IR spectra and their assignments will be discussed as well as other new IR spectra for similar complexes.

  18. Many-body theory of electron-positron interaction in metallic lithium

    Energy Technology Data Exchange (ETDEWEB)

    Stachowiak, H. [Polska Akademia Nauk, Wroclaw (Poland). Inst. Niskich Temperatur i Badan Strukturalnych

    1997-10-01

    Development of hypernetted-chain approach to the electronic structure of simple metals offers the possibility to perform many-body calculations of the electron-positron interaction in these materials. A theory of this interaction is proposed and applied to lithium. It leads to nonlinear three-dimensions integro-differential equation for the enhancement amplitude. This equation is solved for two cases in which it reduces to one dimension. (author). 4 refs, 3 figs.

  19. The interaction of metal carbonyl compounds with organic polymers and monomers

    OpenAIRE

    Lyons, Michael P.

    1993-01-01

    The photochemistry of W(CO)6, Mo(CO)6, and Cr(CO)6 in the presence of monomeric and polymeric triphenylphosphine ligands was investigated in toluene solution, using laser flash photolysis with 355nm excitation. The mechanism and kinetics of interaction of the primary photoproducts M(CO)5(toluene) (M = W, Mo, or Cr) with the various monomeric ligands were investigated. Interaction of the metal carbonyl photofragments with various homopolymers is also discussed. The polymerisation methods used ...

  20. FTIR spectroscopy structural analysis of the interaction between Lactobacillus kefir S-layers and metal ions

    Science.gov (United States)

    Gerbino, E.; Mobili, P.; Tymczyszyn, E.; Fausto, R.; Gómez-Zavaglia, A.

    2011-02-01

    FTIR spectroscopy was used to structurally characterize the interaction of S-layer proteins extracted from two strains of Lactobacillus kefir (the aggregating CIDCA 8348 and the non-aggregating JCM 5818) with metal ions (Cd +2, Zn +2, Pb +2 and Ni +2). The infrared spectra indicate that the metal/protein interaction occurs mainly through the carboxylate groups of the side chains of Asp and Glut residues, with some contribution of the NH groups belonging to the peptide backbone. The frequency separation between the νCOO - anti-symmetric and symmetric stretching vibrations in the spectra of the S-layers in presence of the metal ions was found to be ca. 190 cm -1 for S-layer CIDCA 8348 and ca. 170 cm -1 for JCM 5818, denoting an unidentate coordination in both cases. Changes in the secondary structures of the S-layers induced by the interaction with the metal ions were also noticed: a general trend to increase the amount of β-sheet structures and to reduce the amount of α-helices was observed. These changes allow the proteins to adjust their structure to the presence of the metal ions at minimum energy expense, and accordingly, these adjustments were found to be more important for the bigger ions.

  1. Potentiometric and spectroscopic study of the interaction of 3d transition metal ions with inositol hexakisphosphate

    Science.gov (United States)

    Veiga, Nicolás; Macho, Israel; Gómez, Kerman; González, Gabriel; Kremer, Carlos; Torres, Julia

    2015-10-01

    Among myo-inositol phosphates, the most abundant in nature is the myo-inositol hexakisphosphate, InsP6. Although it is known to be vital to cell functioning, the biochemical research into its metabolism needs chemical and structural analysis of all the protonation, complexation and precipitation processes that it undergoes in the biological media. In view of its high negative charge at physiological level, our group has been leading a thorough research into the InsP6 chemical and structural behavior in the presence of the alkali and alkaline earth metal ions essential for life. The aim of this article is to extend these studies, dealing with the chemical and structural features of the InsP6 interaction with biologically relevant 3d transition metal ions (Fe(II), Fe(III), Mn(II), Co(II), Ni(II), Cu(II) and Zn(II)), in a non-interacting medium and under simulated physiological conditions. The metal-complex stability constants were determined by potentiometry, showing under ligand-excess conditions the formation of mononuclear species in different protonation states. Under metal ion excess, polymetallic species were detected for Fe(II), Fe(III), Zn(II) and Cu(II). Additionally, the 31P NMR and UV-vis spectroscopic studies provided interesting structural aspects of the strong metal ion-InsP6 interaction.

  2. Cellular Specificity of the Blood-CSF Barrier for Albumin Transfer across the Choroid Plexus Epithelium

    DEFF Research Database (Denmark)

    Liddelow, Shane A; Dzięgielewska, Katarzyna M; Møllgård, Kjeld

    2014-01-01

    of transfer of endogenous (mouse) and exogenous (human) albumins, in situ Proximity Ligation Assay (in situ PLA), and qRT-PCR experiments to examine the cellular mechanism mediating protein transfer across the blood-CSF interface. We report that at all developmental stages mouse albumin and SPARC gave...... rarely identifiable within choroid plexus cells and only at older ages. Concentrations of both endogenous mouse albumin and exogenous (intraperitoneally injected) human albumin were estimated in plasma and CSF and expressed as CSF/plasma concentration ratios. Human albumin was not transferred through...... positive signals with in situ PLAs in plasma, CSF and within individual plexus cells suggesting a possible molecular interaction. In contrast, in situ PLA experiments in brain sections from mice injected with human albumin showed positive signals for human albumin in the vascular compartment that were only...

  3. Interactions of alkali metals and electrolyte with cathode carbons

    Energy Technology Data Exchange (ETDEWEB)

    Naas, Tyke

    1997-12-31

    The Hall-Heroult process for electrolytic reduction of alumina has been the only commercial process for production of primary aluminium. The process runs at high temperature and it is important to minimize the energy consumption. To save energy it is desirable to reduce the operating temperature. This can be achieved by adding suitable additives such as LiF or KF to the cryolitic electrolyte. This may conflict with the objective of extending the lifetime of the cathode linings of the cell as much as possible. The thesis investigates this possibility and the nature of the interactions involved. It supports the hypothesis that LiF-additions to the Hall-Heroult cell electrolyte is beneficial to the carbon cathode performance because the diminished sodium activity reduces the sodium induced stresses during the initial period of electrolysis. The use of KF as an additive is more dangerous, but the results indicate that additions up to 5% KF may be tolerated in acidic melts with semigraphitic or graphitic cathodes with little risk of cathode problems. 153 refs., 94 figs., 30 tabs.

  4. Interatomic interaction of additive elements and their influence on the processes in the double metal solutions

    Directory of Open Access Journals (Sweden)

    Марина Анатоліівна Рябікіна

    2016-07-01

    Full Text Available Modern industry uses a lot of elements as additives to improve the service characteristics of metal products that are to be used for various purposes. These elements can be divided into two groups: the first group includes the elements interacting with iron and improving its characteristics (alloying elements, and the second group includes the elements, that modify the characteristics of the structure and properties in an undesirable direction. These are trace elements: S, P, O, As, and others in steel. The negative impact of these elements shows itself as banding, the formation of non-metallic inclusions, flakes, grain boundary segregations et al. The influence of the elements of the both groups on the properties of steel depends on the nature and level of interatomic interaction in the alloy. Computational and analytical study of the major impurity elements in steel impact on the interatomic bond strength and the probability of forming complexes, clusters, and chemical compounds with the basic alloying elements in the steel has been carried out in the work. The theoretical parameter which defines the strength of the ion-covalent bond of two atoms: non-metallicmetallic is the electronegativity of elements. The electronegativity difference of the metal and non-metallic elements increasing, the ionic bonding and thermodynamic stability of these compounds  increase. On the other hand, concentration of valent electrons is a universal characteristic of an atomic element which determines many of its properties, and especially the energy of interatomic interaction. Energy calculations of pairwise interatomic impurity elements: H, C, N, S, P, As interaction with Fe and major alloying elements in steel: Mn, Cr, Si, V, Al, Ti, W, Cu, Mo, Nb were made. It has been stated that all the impurity elements except phosphorus, hydrogen and arsenic have sufficient high adhesion with the majority of the metal elements in the modern steels. Phosphorus does

  5. Determination of heat transfer coefficient for an interaction of sub-cooled gas and metal

    International Nuclear Information System (INIS)

    Sidek, Mohd Zaidi; Kamarudin, Muhammad Syahidan

    2016-01-01

    Heat transfer coefficient (HTC) for a hot metal surface and their surrounding is one of the need be defined parameter in hot forming process. This study has been conducted to determine the HTC for an interaction between sub-cooled gas sprayed on a hot metal surface. Both experiments and finite element have been adopted in this work. Initially, the designated experiment was conducted to obtain temperature history of spray cooling process. Then, an inverse method was adopted to calculate the HTC value before we validate in a finite element simulation model. The result shows that the heat transfer coefficient for interaction of subcooled gas and hot metal surface is 1000 W/m 2 K. (paper)

  6. Ab initio study of solute transition-metal interactions with point defects in bcc Fe

    NARCIS (Netherlands)

    Olsson, P.; Klaver, T.P.C.; Domain, C.

    2010-01-01

    The properties of 3d, 4d, and 5d transition-metal elements in ?-Fe have been studied using ab initio density-functional theory. The intrinsic properties of the solutes have been characterized as well as their interaction with point defects. Vacancies and interstitials of (110) and (111) orientations

  7. Infrared studies of astronomically relevant metallic clusters and their interactions with simple molecules

    NARCIS (Netherlands)

    Kiawi, D.M.

    2016-01-01

    The work presented in this thesis aims at: a) providing fundamental knowledge on the interactions of simple ligands with metal clusters relevant to astronomical and (bio-) catalytical processes, b) providing a benchmark that can be used to test current and future DFT methods developed to study these

  8. Interactions between metal cations with H 2 in the M-H 2 complexes ...

    Indian Academy of Sciences (India)

    Interactions between metal cations with H2 in the M+- H2 complexes: Performance of DFT and DFT-D methods ... Graduate School of Information Science, Nagoya University, Chukusa-ku, Nagoya 464-8601, Aichi, Japan; Department of Spectroscopy, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700 ...

  9. Study of interaction of ethylene glycol/PVP phase on noble metal ...

    Indian Academy of Sciences (India)

    They have been characterized by both microscopic (TEM and SEM) as well as spectroscopic techniques (FT-IR and XPS). Infrared spectroscopy was employed to study the colloid particles in the presence of ethylene glycol and PVP and the results show that the interaction between the organic phase and the metal particles ...

  10. Study of plasma formation in CW CO2 laser beam-metal surface interaction

    Science.gov (United States)

    Azharonok, V. V.; Vasilchenko, Zh V.; Golubev, Vladimir S.; Gresev, A. N.; Zabelin, Alexandre M.; Chubrik, N. I.; Shimanovich, V. D.

    1994-04-01

    An interaction of the cw CO2 laser beam and a moving metal surface has been studied. The pulsed and thermodynamical parameters of the surface plasma were investigated by optical and spectroscopical methods. The subsonic radiation wave propagation in the erosion plasma torch has been studied.

  11. Influence of biogeochemical interactions on metal bioleaching performance in contaminated marine sediment.

    Science.gov (United States)

    Fonti, Viviana; Dell'Anno, Antonio; Beolchini, Francesca

    2013-09-15

    Bioleaching strategies are still far from finding real applications in sediment clean-up, although metabolic mechanisms governing bioleaching processes have been deeply studied and can be considered well established. In this study, we carried out bioleaching experiments, using autotrophic and heterotrophic acidophilic bacteria strains, and worked with marine sediments characterized by different geochemical properties and metal concentrations and speciations. The solubilization efficiency of the metals was highly variable, with the highest for Zn (40%-76%) and the lowest for Pb (0%-7%). Our data suggest that the role of autotrophic Fe/S oxidizing bacteria is mainly associated with the production and re-cycling of leaching chemical species, mainly as protons and ferric ions. Metal solubilization appears to be more related to establishing environmental conditions that allow each metal or semimetal to remain stable in the solution phase. Thus, the maintenance of acid and oxidative conditions, the chemical behavior in aqueous environment of each metal species and the geochemical characteristics of sediment interact intimately to influence metal solubilization in site-specific and metal-specific way. Copyright © 2013 Elsevier Ltd. All rights reserved.

  12. GIANT PLANETS ORBITING METAL-RICH STARS SHOW SIGNATURES OF PLANET-PLANET INTERACTIONS

    International Nuclear Information System (INIS)

    Dawson, Rebekah I.; Murray-Clay, Ruth A.

    2013-01-01

    Gas giants orbiting interior to the ice line are thought to have been displaced from their formation locations by processes that remain debated. Here we uncover several new metallicity trends, which together may indicate that two competing mechanisms deliver close-in giant planets: gentle disk migration, operating in environments with a range of metallicities, and violent planet-planet gravitational interactions, primarily triggered in metal-rich systems in which multiple giant planets can form. First, we show with 99.1% confidence that giant planets with semimajor axes between 0.1 and 1 AU orbiting metal-poor stars ([Fe/H] < 0) are confined to lower eccentricities than those orbiting metal-rich stars. Second, we show with 93.3% confidence that eccentric proto-hot Jupiters undergoing tidal circularization primarily orbit metal-rich stars. Finally, we show that only metal-rich stars host a pile-up of hot Jupiters, helping account for the lack of such a pile-up in the overall Kepler sample. Migration caused by stellar perturbers (e.g., stellar Kozai) is unlikely to account for the trends. These trends further motivate follow-up theoretical work addressing which hot Jupiter migration theories can also produce the observed population of eccentric giant planets between 0.1 and 1 AU.

  13. Strong Cation···π Interactions Promote the Capture of Metal Ions within Metal-Seamed Nanocapsule

    Science.gov (United States)

    2015-01-01

    Thallium ions are transported to the interior of gallium-seamed pyrogallol[4]arene nanocapsules. In comparison to the capture of Cs ions, the extent of which depends on the type and position of the anion employed in the cesium salt, the enhanced strength of Tl···π vs Cs···π interactions facilitates permanent entrapment of Tl+ ions on the capsule interior. “Stitching-up” the capsule seam with a tertiary metal (Zn, Rb, or K) affords new trimetallic nanocapsules in solid state. PMID:25405777

  14. Probing the interaction of human serum albumin with vitamin B2 (riboflavin) and L-Arginine (L-Arg) using multi-spectroscopic, molecular modeling and zeta potential techniques

    Energy Technology Data Exchange (ETDEWEB)

    Memarpoor-Yazdi, Mina [Department of Biology, Faculty of Sciences, Mashhad Branch, Islamic Azad University, Mashhad (Iran, Islamic Republic of); Mahaki, Hanie, E-mail: hanieh.mahaki@gmail.com [Department of Biology, Faculty of Sciences, Mashhad Branch, Islamic Azad University, Mashhad (Iran, Islamic Republic of)

    2013-04-15

    This study was designed to examine the interaction of Riboflavin (RB) and L-Arginine (L-Arg) with human serum albumin (HSA) using different spectroscopic, zeta potential and molecular modeling techniques under imitated physiological conditions. The resonance light scattering (RLS) method determined the critical aggregation concentration of RB on HSA in the presence and absence of L-Arg which confirmed the zeta potential results. The binding constants (K{sub a}) of HSA–RB were 2.5×10{sup 4} and 9.7×10{sup 3} M{sup −1}, respectively in binary and ternary system at the excitation wavelength of 280 nm, also were 7.5×10{sup 3} and 7.3×10{sup 3}, respectively in binary and ternary system at the excitation wavelength of 295 nm. Fluorescence spectroscopy demonstrated that in the presence of L-Arg, the binding constant of HSA–RB was increased. Static quenching was confirmed to results in the fluorescence quenching and FRET. The binding distances between HSA and RB in two- and three-component systems were estimated by the Forster theory which revealed that nonradiative energy transfer from HSA to RB occurred with a high probability. The effect of RB on the conformation of HSA was analyzed using synchronous fluorescence spectroscopy and circular dichroism (CD) in both systems. Docking studies demonstrated a reduction in the binding affinity between RB and HSA in the presence of L-Arg. -- Highlights: ► We studied the interaction of riboflavin with HSA in presence and absence of L-Arg. ► Molecular modeling and zeta-potential used to describe competitive interaction. ► We compared the binding mechanism of riboflavin (RB) to HSA in both systems. ► We determined critical aggregation concentration of RB on HSA in both systems. ► The binding site of RB on HSA in both systems has been determined.

  15. Probing the interaction of human serum albumin with vitamin B2 (riboflavin) and L-Arginine (L-Arg) using multi-spectroscopic, molecular modeling and zeta potential techniques

    International Nuclear Information System (INIS)

    Memarpoor-Yazdi, Mina; Mahaki, Hanie

    2013-01-01

    This study was designed to examine the interaction of Riboflavin (RB) and L-Arginine (L-Arg) with human serum albumin (HSA) using different spectroscopic, zeta potential and molecular modeling techniques under imitated physiological conditions. The resonance light scattering (RLS) method determined the critical aggregation concentration of RB on HSA in the presence and absence of L-Arg which confirmed the zeta potential results. The binding constants (K a ) of HSA–RB were 2.5×10 4 and 9.7×10 3 M −1 , respectively in binary and ternary system at the excitation wavelength of 280 nm, also were 7.5×10 3 and 7.3×10 3 , respectively in binary and ternary system at the excitation wavelength of 295 nm. Fluorescence spectroscopy demonstrated that in the presence of L-Arg, the binding constant of HSA–RB was increased. Static quenching was confirmed to results in the fluorescence quenching and FRET. The binding distances between HSA and RB in two- and three-component systems were estimated by the Forster theory which revealed that nonradiative energy transfer from HSA to RB occurred with a high probability. The effect of RB on the conformation of HSA was analyzed using synchronous fluorescence spectroscopy and circular dichroism (CD) in both systems. Docking studies demonstrated a reduction in the binding affinity between RB and HSA in the presence of L-Arg. -- Highlights: ► We studied the interaction of riboflavin with HSA in presence and absence of L-Arg. ► Molecular modeling and zeta-potential used to describe competitive interaction. ► We compared the binding mechanism of riboflavin (RB) to HSA in both systems. ► We determined critical aggregation concentration of RB on HSA in both systems. ► The binding site of RB on HSA in both systems has been determined

  16. Low concentration toxic metal mixture interactions: Effects on essential and non-essential metals in brain, liver, and kidneys of mice on sub-chronic exposure.

    Science.gov (United States)

    Cobbina, Samuel J; Chen, Yao; Zhou, Zhaoxiang; Wu, Xueshan; Feng, Weiwei; Wang, Wei; Mao, Guanghua; Xu, Hai; Zhang, Zhen; Wu, Xiangyang; Yang, Liuqing

    2015-08-01

    The deleterious effects of long term exposure to individual toxic metals in low doses are well documented. There is however, a paucity of information on interaction of low dose toxic metal mixtures with toxic and essential metals. This study reports on interactions between low dose mixtures of lead (Pb), mercury (Hg), arsenic (As) and cadmium (Cd) and toxic and essential metals. For 120d, six groups of forty mice each were exposed to metal mixtures, however, the control group was given distilled water. Exposure to Pb+Cd increased brain Pb by 479% in 30d, whiles Pb+Hg+As+Cd reduced liver Hg by 46.5%, but increased kidney As by 130% in 30d. Brain Cu, increased by 221% on Pb+Hg+As+Cd exposure, however, liver Ca reduced by 36.1% on Pb+Hg exposure in 60-d. Interactions within metal mixtures were largely synergistic. Principal component analysis (PCA) showed that low dose metal exposures influenced greatly levels of Hg (in brain and liver) and As (brain). The influence exerted on essential metals was highest in liver (PC1) followed by kidney (PC2) and brain (PC3). Exposure to low dose metal mixtures affected homeostasis of toxic and essential metals in tissues of mice. Copyright © 2015 Elsevier Ltd. All rights reserved.

  17. SUPPORTING INFORMATION Bovine Serum Albumin Metal ...

    Indian Academy of Sciences (India)

    Sky123.Org

    GUIFANG YAN, YUFENG HE*, GANG LI, YUBING XIONG, PENGFEI SONG and RONG-MIN WANG*. Key Lab. Eco-Environment-Related Polymer Materials of Ministry of Education, Key Lab. Polymer Materials of Gansu Province, College of Chemistry & Chemical Engineering, Northwest Normal University, Lanzhou 730070, ...

  18. Study of the interaction between two newly synthesized cyclometallated platinum (II) complexes and human serum albumin: Spectroscopic characterization and docking simulation

    Energy Technology Data Exchange (ETDEWEB)

    Yousefi, Reza, E-mail: ryousefi@shirazu.ac.ir [Protein Chemistry Laboratory (PCL), Department of Biology, College of Sciences, Shiraz University, Shiraz (Iran, Islamic Republic of); Mohammadi, Roghayeh [Protein Chemistry Laboratory (PCL), Department of Biology, College of Sciences, Shiraz University, Shiraz (Iran, Islamic Republic of); Taheri-Kafrani, Asghar [Department of Biotechnology, Faculty of Advanced Sciences and Technologies, University of Isfahan, Isfahan 81746-73441 (Iran, Islamic Republic of); Bagher Shahsavani, Mohammad [Protein Chemistry Laboratory (PCL), Department of Biology, College of Sciences, Shiraz University, Shiraz (Iran, Islamic Republic of); Dadkhah Aseman, Marzieh; Masoud Nabavizadeh, S.; Rashidi, Mehdi [Department of Chemistry, College of Sciences, Shiraz University, Shiraz (Iran, Islamic Republic of); Poursasan, Najmeh; Moosavi-Movahedi, Ali-Akbar [Institute of Biochemistry and Biophysics (IBB), the University of Tehran, Tehran (Iran, Islamic Republic of)

    2015-03-15

    This study describes HSA binding properties of two cyclometalated platinum (II) complexes with non-leaving lipophilic ligands; deprotonated 2-phenylpyridine (ppy): C{sub 1} and deprotonated benzo [h]quinolone (bhq): C{sub 2}, using UV–vis, fluorescence and circular dichroism (CD) spectroscopy. The absorption spectra of HSA decreased in the presence of increasing concentration of these complexes, reflecting HSA structural alteration after drug's binding. Also the thermodynamic parameters (ΔG, ΔH and ΔS) that obtained from Trp fluorescence study revealed that the interaction between these complexes and HSA were spontaneous. In addition, C{sub 1} with flexible chemical structure indicated significantly higher fluorescence quenching and binding affinity to HSA than C{sub 2} which possesses a higher structural rigidity. The ANS fluorescence results also indicated that two Pt (II) complexes were competing for binding to the hydrophobic regions of HSA. Moreover, CD results demonstrated that C{sub 2} complex induced alteration of HSA conformation to more significant extent compared to C{sub 1}. The molecular docking results revealed the involvement of π–π stacking and hydrophobic interaction between these complexes and the protein. Overall, this study may highlight the significance of structural flexibility in designing of future anticancer Pt (II) complexes with improved binding affinity for HSA. - Highlights: • HSA is a general transport carrier for a wide variety of ligands such as metabolites and pharmaceutical drugs. • The HSA binding properties of two structurally related cyclometallated platinum (II) complexes (C{sub 1} and C{sub 2}) were studied. • The complexes can bind to HSA and induce structural alteration in this protein. • The thermodynamic parameters revealed that the interactions were spontaneous and mainly hydrophobic driven. • C{sub 1} with flexible chemical structure indicated a higher binding affinity for HSA than C{sub 2}.

  19. Spectroscopic analyses on interaction of o-Vanillin- D-Phenylalanine, o-Vanillin- L-Tyrosine and o-Vanillin- L-Levodopa Schiff Bases with bovine serum albumin (BSA)

    Science.gov (United States)

    Gao, Jingqun; Guo, Yuwei; Wang, Jun; Wang, Zhiqiu; Jin, Xudong; Cheng, Chunping; Li, Ying; Li, Kai

    2011-04-01

    In this work, three o-Vanillin Schiff Bases (o-VSB: o-Vanillin- D-Phenylalanine (o-VDP), o-Vanillin- L-Tyrosine (o-VLT) and o-Vanillin- L-Levodopa (o-VLL)) with alanine constituent were synthesized by direct reflux method in ethanol solution, and then were used to study the interaction to bovine serum albumin (BSA) molecules by fluorescence spectroscopy. Based on the fluorescence quenching calculation, the bimolecular quenching constant ( Kq), apparent quenching constant ( Ksv), effective binding constant ( KA) and corresponding dissociation constant ( KD) as well as binding site number ( n) were obtained. In addition, the binding distance ( r) was also calculated according to Foster's non-radioactive energy transfer theory. The results show that these three o-VSB can efficiently bind to BSA molecules, but the binding array order is o-VDP-BSA > o-VLT-BSA > o-VLL-BSA. Synchronous fluorescence spectroscopy indicates that the o-VDP is more accessibility to tryptophan (Trp) residues of BSA molecules than to tyrosine (Tyr) residues. Nevertheless, the o-VLT and o-VLL are more accessibility to Tyr residues than to Trp residues.

  20. Interaction of lafutidine in binding to human serum albumin in gastric ulcer therapy: STD-NMR, WaterLOGSY-NMR, NMR relaxation times, Tr-NOESY, molecule docking, and spectroscopic studies.

    Science.gov (United States)

    Yang, Hongqin; Huang, Yanmei; He, Jiawei; Li, Shanshan; Tang, Bin; Li, Hui

    2016-09-15

    In this study, lafutidine (LAF) was used as a model compound to investigate the binding mechanism between antiulcer drugs and human serum albumin (HSA) through various techniques, including STD-NMR, WaterLOGSY-NMR, (1)H NMR relaxation times, tr-NOESY, molecule docking calculation, FT-IR spectroscopy, and CD spectroscopy. The analyses of STD-NMR, which derived relative STD (%) intensities, and WaterLOGSY-NMR, determined that LAF bound to HSA. In particular, the pyridyl group of LAF was in close contact with HSA binding pocket, whereas furyl group had a secondary binding. Competitive STD-NMR and WaterLOGSY-NMR experiments, with warifarin and ibuprofen as site-selective probes, indicated that LAF preferentially bound to site II in the hydrophobic subdomains IIIA of HSA. The bound conformation of LAF at the HSA binding site was further elucidated by transferred NOE effect (tr-NOESY) experiment. Relaxation experiments provided quantitative information about the relationship between the affinity and structure of LAF. The molecule docking simulations conducted with AutoDock and the restraints derived from STD results led to three-dimensional models that were consistent with the NMR spectroscopic data. The presence of hydrophobic forces and hydrogen interactions was also determined. Additionally, FT-IR and CD spectroscopies showed that LAF induced secondary structure changes of HSA. Copyright © 2016 Elsevier Inc. All rights reserved.

  1. Stress-Corrosion Interactions in Zr-Based Bulk Metallic Glasses

    Directory of Open Access Journals (Sweden)

    Petre Flaviu Gostin

    2015-07-01

    Full Text Available Stress-corrosion interactions in materials may lead to early unpredictable catastrophic failure of structural parts, which can have dramatic effects. In Zr-based bulk metallic glasses, such interactions are particularly important as these have very high yield strength, limited ductility, and are relatively susceptible to localized corrosion in halide-containing aqueous environments. Relevant features of the mechanical and corrosion behavior of Zr-based bulk metallic glasses are described, and an account of knowledge regarding corrosion-deformation interactions gathered from ex situ experimental procedures is provided. Subsequently the literature on key phenomena including hydrogen damage, stress corrosion cracking, and corrosion fatigue is reviewed. Critical factors for such phenomena will be highlighted. The review also presents an outlook for the topic.

  2. Competing interactions of noble metals and fullerenes with the Si(111)7x7 surface

    International Nuclear Information System (INIS)

    O'Shea, J.N.; Phillips, M.A.; Taylor, M.D.R.; Beton, P.H.; Moriarty, P.; Kanai, M.; Dennis, T.S.J.; Dhanak, V.R.

    2004-01-01

    Full text: Synchrotron-based photoelectron spectroscopy (PES) has been used to investigate the interaction of atomic gold and silver with a covalently bound C 60 -monolayer adsorbed on Si(111)7x7. In contrast to the relatively benign interaction of silver with the C 60 /Si(111)7x7 surface, core-level photoemission data reveal a strong interaction of the gold with the underlying silicon despite the presence of a chemisorbed fullerene monolayer. The Si 2p PES data exhibit dramatic changes consistent with the formation of a gold silicide, which is also evident from the corresponding Au 4f spectra. Valence band photoemission also reveals the absence of appreciable density of states at the Fermi level following the adsorption of either metal, indicating a negligible transfer of electrons from the adsorbed metal to the C 60 cage

  3. Graphene as a flexible template for controlling magnetic interactions between metal atoms.

    Science.gov (United States)

    Lee, Sungwoo; Kim, Dongwook; Robertson, Alex W; Yoon, Euijoon; Hong, Suklyun; Ihm, Jisoon; Yu, Jaejun; Warner, Jamie H; Lee, Gun-Do

    2017-03-01

    Metal-doped graphene produces magnetic moments that have potential application in spintronics. Here we use density function theory computational methods to show how the magnetic interaction between metal atoms doped in graphene can be controlled by the degree of flexure in a graphene membrane. Bending graphene by flexing causes the distance between two substitutional Fe atoms covalently bonded in graphene to gradually increase and these results in the magnetic moment disappearing at a critical strain value. At the critical strain, a carbon atom can enter between the two Fe atoms and blocks the interaction between relevant orbitals of Fe atoms to quench the magnetic moment. The control of interactions between doped atoms by exploiting the mechanical flexibility of graphene is a unique approach to manipulating the magnetic properties and opens up new opportunities for mechanical-magnetic 2D device systems.

  4. Results of measurements of thermal interaction between molten metal and water

    International Nuclear Information System (INIS)

    Zyszkowski, W.

    1975-10-01

    The report describes results of an experimental investigation into thermal interaction of molten metals with water. The experiments were performed in two stages: the aim of the first stage was to study the general character of thermal interaction between molten metal and water and to measure the Leidenfrost temperature of the inverse Leidenfrost phenomenon. The second stage was directed to the experimental study of the triggering mechanism of thermal explosion. The experimental material gathered in this study includes: 1) transient temperature measurements in the hot material and in water, 2) measurements of pressure and reactive force combined with thermal explosion, 3) high-speed films of thermal interaction, 4) investigation results of thermal explosion debris (microscopic, mechanical, metallographical and chemical). The most significant observation is, that small jets from the main particle mass occuring 1 to 10 msec before, precede thermal explosion. (orig.) [de

  5. Understanding Trends in Catalytic Activity: The Effect of Adsorbate-Adsorbate Interactions for CO Oxidation Over Transition Metals

    DEFF Research Database (Denmark)

    Grabow, Lars; Larsen, Britt Hvolbæk; Nørskov, Jens Kehlet

    2010-01-01

    Using high temperature CO oxidation as the example, trends in the reactivity of transition metals are discussed on the basis of density functional theory (DFT) calculations. Volcano type relations between the catalytic rate and adsorption energies of important intermediates are introduced...... and the effect of adsorbate-adsorbate interaction on the trends is discussed. We find that adsorbate-adsorbate interactions significantly increase the activity of strong binding metals (left side of the volcano) but the interactions do not change the relative activity of different metals and have a very small...... influence on the position of the top of the volcano, that is, on which metal is the best catalyst....

  6. Interplay between cation-π and coinage-metal-oxygen interactions: an ab initio study and Cambridge Structural Database survey.

    Science.gov (United States)

    Gao, Meng; Li, Qingzhong; Li, Wenzuo; Cheng, Jianbo

    2015-04-07

    The interplay between cation-π and coinage-metal-oxygen interactions are investigated in the ternary systems N⋅⋅⋅PhCCM⋅⋅⋅O (N=Li(+), Na(+), Mg(2+); M=Ag, Au; O=water, methanol, ethanol). A synergetic effect is observed when cation-π and coinage-metal-oxygen interactions coexist in the same complex. The cation-π interaction in most triads has a greater enhancing effect on the coinage-metal-oxygen interaction. This effect is analyzed in terms of the binding distance, interaction energy, and electrostatic potential in the complexes. Furthermore, the formation, strength, and nature of both the cation-π and coinage-metal-oxygen interactions can be understood in terms of electrostatic potential and energy decomposition. In addition, experimental evidence for the coexistence of both interactions is obtained from the Cambridge Structural Database (CSD). © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Ghrelin binding to serum albumin and its biological impact.

    Science.gov (United States)

    Lufrano, Daniela; Trejo, Sebastián A; Llovera, Ramiro E; Salgueiro, Mariano; Fernandez, Gimena; Martínez Damonte, Valentina; González Flecha, F Luis; Raingo, Jesica; Ermácora, Mario R; Perelló, Mario

    2016-11-15

    Ghrelin is an octanoylated peptide hormone that plays a key role in the regulation of the body weight and glucose homeostasis. In plasma, ghrelin circulates bound to larger proteins whose identities are partially established. Here, we used size exclusion chromatography, mass spectrometry and isothermal titration microcalorimetry to show that ghrelin interacts with serum albumin. Furthermore, we found that such interaction displays an estimated dissociation constant (KD) in the micromolar range and involves albumin fatty-acid binding sites as well as the octanoyl moiety of ghrelin. Notably, albumin-ghrelin interaction reduces the spontaneous deacylation of the hormone. Both in vitro experiments-assessing ghrelin ability to inhibit calcium channels-and in vivo studies-evaluating ghrelin orexigenic effects-indicate that the binding to albumin affects the bioactivity of the hormone. In conclusion, our results suggest that ghrelin binds to serum albumin and that this interaction impacts on the biological activity of the hormone. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  8. Molecular dynamics simulations of the DNA interaction with metallic nanoparticles and TiO2 surfaces

    International Nuclear Information System (INIS)

    Kholmurodov, Kh.T.; Krasavin, E.A.; Dushanov, E.B.; Hassan, H.K.; Galal, A.; ElHabashy, H.A.; Sweilam, N.H.; Yasuoka, K.

    2013-01-01

    The understanding of the mechanism of DNA interactions and binding with metallic nanoparticles (NPs) and surfaces represents a great interest in today's medicine applications due to diagnostic and treatment of oncology diseases. Recent experimental and simulation studies involve the DNA interaction with highly localized proton beams or metallic NPs (such as Ag, Au, etc.), aimed at targeted cancer therapy through the injection of metal micro- or nanoparticles into the tumor tissue with consequent local microwave or laser heating. The effects of mutational structure changes in DNA and protein structures could result in destroying of native chemical (hydrogen) bonds or, on the contrary, creating of new bonds that do not normally exist there. The cause of such changes might be the alteration of one or several nucleotides (in DNA) or the substitution of specific amino acid residues (in proteins) that can lead to the essential structural destabilization or unfolding. At the atomic or molecular level, the replacement of one nucleotide by another (in DNA double helices) or replacement of one amino acid residue by another (in proteins) cause essential modifications of the molecular force fields of the environment that break locally important hydrogen bonds underlying the structural stability of the biological molecules. In this work, the molecular dynamics(MD) simulations were performed for four DNA models and the flexibilities of the purine and pyrimidine nucleotides during the interaction process with the metallic NPs and TiO 2 surface were clarified

  9. Misunderstandings connected with the problem of electron-positron interaction in metals

    Energy Technology Data Exchange (ETDEWEB)

    Stachowiak, H.; Boronski, E. [Polska Akademia Nauk, Wroclaw (Poland). Inst. Niskich Temperatur i Badan Strukturalnych

    1997-10-01

    It is pointed out that some misunderstandings concerning the theory of electron-positron interaction are an obstacle in a reliable experimental determination of the annihilation characteristics in simple metals. A two step program of reaching progress in this direction is proposed. First a definitive conclusion concerning the applicability of the consequently many-body approach of Arponen and Pajanne in describing positron annihilation in metals. Then a precise determination of the momentum dependence of enhancement, since the approximate biquadratic formula of Kahana, generally and uncritically used by experimentalists, differs in an essential way from the exact solution of the Kahana equation. (author). 17 refs, 1 fig., 1 tab.

  10. Metals interaction tested in children’s hair originating from industrial and rural areas

    Directory of Open Access Journals (Sweden)

    Jerzy Kwapulinski

    2014-09-01

    Full Text Available Introduction. Different biological samples (blood, gallstone, teeth, hair serve as a biomarker of exposure to metals for many years. This method appeared to be useful not only in clinical medicine, but also in the studies on the environment. Aim. The study is to compare the amount of selected metals in children’s hair residing in industrial and rural areas. Material and methods. Research of occurrence of 12 metals in children’s hair at the age of 7, 10 and 14 living in an industrial (Nowy Bytom town and a rural (Strumień town areas has been presented. Determination of Pb, Cd, Ni, Co Na, K, Mg, Zn, Cu, Mn, Fe and Ca was carried out by atomic absorption spectrophotometry (AAS using a spectrometer PerkinElmer 400. Results. In the case of seven-year old children, regardless of gender a common mechanism of co-occurrence was noticed for manganese and calcium, manganese and magnesium, calcium and magnesium, sodium and potassium. Apart from the correlation of metals for the seven-year-old-children mentioned, in case of ten-year old children, an additional correlation between calcium and zinc appears. Conclusion: The amount of some metals in the hair with the diversified possibility of interaction between the metals themselves and their relation to gender and age of children revealed different environmental exposure.

  11. Lanthanum, cerium, praseodymium, and neodymium metals and their interaction with oxygen studied by photoelectron spectroscopy

    International Nuclear Information System (INIS)

    Platau, A.

    1982-01-01

    Clean films of La, Ce, Pr, and Nd, prepared by in situ evaporation have been investigated by photoelectron spectroscopy. Different light sources He I (hv = 21.2 eV), He II (hv = 40.8 eV) and Mg Kα (hv = 1253.6 eV) have been used for the electron excitation in order to characterize the metals. Measurements have been performed after exposing the clean metals to various amounts of oxygen. From the vanishing of the emission from the sd conduction band upon exposure the conclusion is drawn that an oxide layer thicker than the probing depth (20 A) is formed on all four metals and that the oxide (at room temperature) has the form: Me 2 O 3 , Me=La, Ce, Pr, Nd. The tetravalent cerium oxide is obtained when the film is heated to about 600 0 C during oxygen exposure. The interaction with oxygen is also characterized by recording the oxygen 1s level and some metal core levels (Me 3d, 4d and 4p). The results from the pure metals and from the metal oxides give further experimental evidence for a 4f level binding energy of 1.9 eV in γ-cerium. (Auth.)

  12. Capturing the H 2 –Metal Interaction in Mg-MOF-74 Using Classical Polarization

    KAUST Repository

    Pham, Tony

    2014-10-02

    © 2014 American Chemical Society. Grand canonical Monte Carlo (GCMC) simulations of H2 sorption were performed in Mg-MOF-74, a metal-organic framework (MOF) that displays very high H2 sorption affinity. Experimental H2 sorption isotherms and isosteric heats of adsorption (Qst) values were reproduced using a general purpose materials sorption potential that includes many-body polarization interactions. In contrast, using two models that include only charge-quadrupole interactions failed to reproduce such experimental measurements even though they are the type normally employed in such classical force field calculations. Utilizing the present explicit polarizable model in GCMC simulation resulted in a Mg2+-H2 distance of 2.60 Å, which is close to a previously reported value that was obtained using electronic structure methods and comparable to similar experimental measurements. The induced dipole distribution obtained from simulation assisted in the characterization of two previously identified sorption sites in the MOF: the Mg2+ ions and the oxido group of the linkers. The calculated two-dimensional quantum rotational levels for a H2 molecule sorbed onto the Mg2+ ion were in good agreement with experimental inelastic neutron scattering (INS) data. Although the H2-metal interaction in MOFs may be thought of as a quantum mechanical effect, this study demonstrates how the interaction between the sorbate molecules and the open-metal sites in a particular highly sorbing MOF can be captured using classical simulation techniques that involve a polarizable potential.

  13. Single-ion and pair-interaction potentials near simple metal surfaces

    International Nuclear Information System (INIS)

    Barnett, R.N.; Barrera, R.G.; Cleveland, C.L.; Landman, U.

    1983-01-01

    Presented is a model for semi-infinite simple metals which does not require crystalline order or a single species, and thus is applicable to problems of defect energetics near the surface and random-alloy surfaces as well as ideal metal surfaces. The formulation is based on the use of ionic pseudopotentials and linear-response theory. An expression for the total energy is obtained which depends explicitly on ionic species and position. This expression is decomposed into a density-dependent term and single-ion and ionic pair-interaction potential terms. The single-ion potentials oscillate about a constant bulk value, with the magnitude of the oscillation decreasing rapidly away from the surface. The interaction between pairs of ions near the surface is shown to be a noncentral force interaction which differs significantly from the central-force bulk pair potential. The effect of quantum interference in the response of the semi-infinite electron gas to the ions is seen in both the single-ion and the pair-interaction potentials. Results are presented for the simple metals sodium, potassium, and rubidium

  14. Interactions between natural organic ligands and trace metals studied by fluorescence lifetime and fluorescence quenching

    Science.gov (United States)

    Nouhi, Ayoub; Hajjoul, Houssam; Redon, Roland; Gagné, Jean-Pierre; Mounier, Stéphane

    2017-04-01

    Improved insight on the interactions between natural organic ligands and trace metals is of paramount importance for better understanding transport and toxicity pathways of metal ions in the environment. Fluorescence spectroscopy allows introspecting ligands-metals interactions. Time-resolved laser fluorescence spectroscopy (TRLFS) measures fluorophore lifetime probing the local molecular environment. Excitation Emission Fluorescence Matrices (EEFMs) and their statistical treatment : parallel factor analysis (PARAFAC) using PROGMEEF Matlab homemade program, can give insight on the number or nature of organic fluorophores involved in the interactions. Quenching of fluorescence by metals can occur following two processes: dynamic and static quenching (Lakowicz, 2013). In the first case, quenching is caused by physical collisions among molecules and in the second case fluorophores can form nonfluorescent complexes with quenchers. It is possible to identify the different mechanisms because each type of quenching corresponds to a different mathematical model (Lakowicz, 2013; Valeur and Berberan-Santos, 2012). In TRLFS, the study of fluorescence decay's laws induced by nanosecond pulsed laser will allow to exactly qualify the type of interaction. The crucial point of the temporal deconvolution will be the evaluation of the best fitting between the different physical models and the decays measured. From the most suitable time decay model, it will be possible to deduce the quenching which modifies the fluorescence. The aim of this study was to characterize interactions between natural organic ligands and trace metals using fluorescence tools to evaluate the fluorescence lifetime of the fluorophore, the occurrence of quenching in presence of metal, discuss its mechanism and estimate conditional stability constants if a complex organic ligand-metal is formed. This study has been done in two steps. First, we have examined the interactions between salicylic acid and copper in

  15. Electrostatically enhanced FF interactions through hydrogen bonding, halogen bonding and metal coordination: an ab initio study.

    Science.gov (United States)

    Bauzá, Antonio; Frontera, Antonio

    2016-07-27

    In this manuscript the ability of hydrogen and halogen bonding interactions, as well as metal coordination to enhance FF interactions involving fluorine substituted aromatic rings has been studied at the RI-MP2/def2-TZVPD level of theory. We have used 4-fluoropyridine, 4-fluorobenzonitrile, 3-(4-fluorophenyl)propiolonitrile and their respective meta derivatives as aromatic compounds. In addition, we have used HF and IF as hydrogen and halogen bond donors, respectively, and Ag(i) as the coordination metal. Furthermore, we have also used HF as an electron rich fluorine donor entity, thus establishing FF interactions with the above mentioned aromatic systems. Moreover, a CSD (Cambridge Structural Database) search has been carried out and some interesting examples have been found, highlighting the impact of FF interactions involving aromatic fluorine atoms in solid state chemistry. Finally, cooperativity effects between FF interactions and both hydrogen and halogen bonding interactions have been analyzed and compared. We have also used Bader's theory of "atoms in molecules" to further describe the cooperative effects.

  16. Hydrogen interaction with GaN metal-insulator-semiconductor diodes

    International Nuclear Information System (INIS)

    Irokawa, Y.

    2012-01-01

    Interaction mechanism of hydrogen with GaN metal-insulator-semiconductor (MIS) diodes is investigated, focusing on the metal/semiconductor interfaces. For MIS Pt-GaN diodes with a SiO 2 dielectric, the current-voltage (I-V) characteristics reveal that hydrogen changes the conduction mechanisms from Fowler-Nordheim tunneling to Poole-Frenkel emission. In sharp contrast, Pt-Si x N y -GaN diodes exhibit Poole-Frenkel emission in nitrogen and do not show any change in the conduction mechanism upon exposure to hydrogen. The capacitance-voltage (C-V) study suggests that the work function change of the Schottky metal is not responsible mechanism for the hydrogen sensitivity.

  17. Versatile Tool for the Analysis of Metal-Protein Interactions Reveals the Promiscuity of Metallodrug-Protein Interactions.

    Science.gov (United States)

    Lee, Ronald F S; Menin, Laure; Patiny, Luc; Ortiz, Daniel; Dyson, Paul J

    2017-11-21

    Metallodrug-protein interactions contribute to their therapeutic effect (even when DNA is the dominant target), side-effects and are implicit in drug resistance. Here, we provide mass spectrometric-based evidence to show that metallodrug interactions with proteins are considerably more complex than current literature would suggest. Using native-like incubation and electrospray conditions together with an automated tool we designed for exhaustive mass spectra matching, the promiscuity of binding of cisplatin to ubiquitin is revealed, with 14 different binding sites observed. There is a binding preference to negatively charged sites on the protein, consistent with the cationic nature of the cisplatin adduct following aquation. These results have implications in metallodrug development and beyond to the toxicological effects of metal ions more generally.

  18. Feedback interactions between trace metal nutrients and phytoplankton in the ocean

    Directory of Open Access Journals (Sweden)

    William eSunda

    2012-06-01

    Full Text Available In addition to control by major nutrient elements (nitrogen, phosphorus, and silicon the productivity and species composition of marine phytoplankton communities are affected by a number of trace metal nutrients (iron, zinc, cobalt, manganese, copper, and cadmium. Of these, iron exerts the greatest limiting influence on carbon fixation rates and has the greatest effect on algal species diversity. It also plays an important role in limiting di-nitrogen (N2 fixation rates, and thus exerts an important influence on ocean inventories of biologically available fixed nitrogen. Because of these effects, iron is thought to play a key role in controlling the biological cycles of carbon and nitrogen in the ocean, including the biological transfer of carbon to the deep sea, the so-called biological CO2 pump, which helps regulate atmospheric CO2 levels and CO2-linked global warming. Other trace metal nutrients (zinc, cobalt, copper, and manganese have a lesser effect on productivity; but may exert an important influence on the species composition of algal communities because of large differences in metal requirements among algal species. The interactions between trace metals and ocean plankton are reciprocal: not only do the metals affect the plankton, but the plankton regulate the distributions, chemical speciation, and cycling of these metals through cellular uptake and regeneration processes, downward flux of biogenic particles, cellular release of organic chelators, and mediation of redox reactions. This two way interaction has influenced not only the biology and chemistry of the modern ocean, but has had a profound influence on biogeochemistry of the ocean and earth system as a whole, and on the evolution marine and terrestrial biology over geologic history.

  19. Feedback Interactions between Trace Metal Nutrients and Phytoplankton in the Ocean

    Science.gov (United States)

    Sunda, William G.

    2012-01-01

    In addition to control by major nutrient elements (nitrogen, phosphorus, and silicon) the productivity and species composition of marine phytoplankton communities are also regulated by a number of trace metal nutrients (iron, zinc, cobalt, manganese, copper, and cadmium). Of these, iron is most limiting to phytoplankton growth and has the greatest effect on algal species diversity. It also plays an important role in limiting di-nitrogen (N2) fixation rates, and thus is important in controlling ocean inventories of fixed nitrogen. Because of these effects, iron is thought to play a key role in regulating biological cycles of carbon and nitrogen in the ocean, including the biological transfer of carbon to the deep sea, the so-called biological CO2 pump, which helps regulate atmospheric CO2 and CO2-linked global warming. Other trace metal nutrients (zinc, cobalt, copper, and manganese) have lesser effects on productivity; but may exert an important influence on the species composition of algal communities because of large differences in metal requirements among species. The interactions between trace metals and ocean plankton are reciprocal: not only do the metals control the plankton, but the plankton regulate the distributions, chemical speciation, and cycling of these metals through cellular uptake and recycling processes, downward flux of biogenic particles, biological release of organic chelators, and mediation of redox reactions. This two way interaction has influenced not only the biology and chemistry of the modern ocean, but has had a profound influence on biogeochemistry of the ocean and earth system as a whole, and on the evolution of marine and terrestrial biology over geologic history. PMID:22701115

  20. Modeling Dzyaloshinskii-Moriya Interaction at Transition Metal Interfaces: Constrained Moment versus Generalized Bloch Theorem

    KAUST Repository

    Dong, Yao-Jun

    2017-10-29

    Dzyaloshinskii-Moriya interaction (DMI) at Pt/Co interfaces is investigated theoretically using two different first principles methods. The first one uses the constrained moment method to build a spin spiral in real space, while the second method uses the generalized Bloch theorem approach to construct a spin spiral in reciprocal space. We show that although the two methods produce an overall similar total DMI energy, the dependence of DMI as a function of the spin spiral wavelength is dramatically different. We suggest that long-range magnetic interactions, that determine itinerant magnetism in transition metals, are responsible for this discrepancy. We conclude that the generalized Bloch theorem approach is more adapted to model DMI in transition metal systems, where magnetism is delocalized, while the constrained moment approach is mostly applicable to weak or insulating magnets, where magnetism is localized.

  1. Electronic metal-support interaction enhanced oxygen reduction activity and stability of boron carbide supported platinum

    Science.gov (United States)

    Jackson, Colleen; Smith, Graham T.; Inwood, David W.; Leach, Andrew S.; Whalley, Penny S.; Callisti, Mauro; Polcar, Tomas; Russell, Andrea E.; Levecque, Pieter; Kramer, Denis

    2017-06-01

    Catalysing the reduction of oxygen in acidic media is a standing challenge. Although activity of platinum, the most active metal, can be substantially improved by alloying, alloy stability remains a concern. Here we report that platinum nanoparticles supported on graphite-rich boron carbide show a 50-100% increase in activity in acidic media and improved cycle stability compared to commercial carbon supported platinum nanoparticles. Transmission electron microscopy and x-ray absorption fine structure analysis confirm similar platinum nanoparticle shapes, sizes, lattice parameters, and cluster packing on both supports, while x-ray photoelectron and absorption spectroscopy demonstrate a change in electronic structure. This shows that purely electronic metal-support interactions can significantly improve oxygen reduction activity without inducing shape, alloying or strain effects and without compromising stability. Optimizing the electronic interaction between the catalyst and support is, therefore, a promising approach for advanced electrocatalysts where optimizing the catalytic nanoparticles themselves is constrained by other concerns.

  2. Induction of subterahertz surface waves on a metal wire by intense laser interaction with a foil

    Science.gov (United States)

    Teramoto, Kensuke; Inoue, Shunsuke; Tokita, Shigeki; Yasuhara, Ryo; Nakamiya, Yoshihide; Nagashima, Takeshi; Mori, Kazuaki; Hashida, Masaki; Sakabe, Shuji

    2018-02-01

    We have demonstrated that a pulsed electromagnetic wave (Sommerfeld wave) of subterahertz frequency and 11-MV/m field strength can be induced on a metal wire by the interaction of an intense femtosecond laser pule with an adjacent metal foil at a laser intensity of 8.5 × 1018W /c m2 . The polarity of the electric field of this surface wave is opposite to that obtained by the direct interaction of the laser with the wire. Numerical simulations suggest that an electromagnetic wave associated with electron emission from the foil induces the surface wave. A tungsten wire is placed normal to an aluminum foil with a gap so that the wire is not irradiated and damaged by the laser pulse, thus making it possible to generate surface waves on the wire repeatedly.

  3. Indium-defect interactions in FCC and BCC metals studied using the modified embedded atom method

    Energy Technology Data Exchange (ETDEWEB)

    Zacate, M. O., E-mail: zacatem1@nku.edu [Northern Kentucky University, Department of Physics, Geology, and Engineering Technology (United States)

    2016-12-15

    With the aim of developing a transferable potential set capable of predicting defect formation, defect association, and diffusion properties in a wide range of intermetallic compounds, the present study was undertaken to test parameterization strategies for determining empirical pair-wise interaction parameters in the modified embedded atom method (MEAM) developed by Baskes and coworkers. This report focuses on indium-solute and indium-vacancy interactions in FCC and BCC metals, for which a large set of experimental data obtained from perturbed angular correlation measurements is available for comparison. Simulation results were found to be in good agreement with experimental values after model parameters had been adjusted to reproduce as best as possible the following two sets of quantities: (1) lattice parameters, formation enthalpies, and bulk moduli of hypothetical equiatomic compounds with the NaCl crystal structure determined using density functional theory and (2) dilute solution enthalpies in metals as predicted by Miedema’s semi-empirical model.

  4. Studies on selected organic-metal interactions of importance in the environment

    International Nuclear Information System (INIS)

    Mason, Ian.

    1995-10-01

    This research project investigated the interaction between natural organics acids and selected metal ions. The aims of the project was to provide quantitative data on the speciation of metal ions when placed in systems containing natural organic acids. It was envisaged that such data will assist in the risk assessment of the Drigg low level waste site in Cumbria. The formation and complexing ability of these natural organic acids is discussed and the classing of these acids into high molecular weight organic acids and low molecular weight organic acids. Initial investigations used a potentiometric technique to study the interaction between nickel and europium and selected low molecular weight organic acids which were thought to occur in significant concentrations in soils and groundwaters. These experiments confirmed existing critically assessed literature values, and provided an experimental methodology for further 'in-house' measurement of such values. In addition, studies were also performed on systems containing two competing organic acids. (author)

  5. Calculation of quadrupole interactions in the high pressure phase of β-gallium metal

    International Nuclear Information System (INIS)

    Acharya, B.K.; Mohapatra, N.C.

    1998-01-01

    Electric field gradient q and quadrupole interaction frequency ν calculated at 256.7 K in the high pressure phase (orthorhombic) of β- Ga metal are reported. The results are: q=+0.251 atomic units (au), ν=5.479 MHz. These are compared with results from experiment and previous calculation available for the monoclinic phase of β- Ga metal at normal pressure. The results from the previous calculation at 248 K are: q=-0.250 au and ν=5.318 MHz. The result from experiment extrapolated to 256.7 K is: ν=4.871 MHz. The sign reversal of the calculated q is attributed mainly to the change of point symmetry of the lattice from the orthorhombic to monoclinic. That the interaction frequency in high pressure phase is higher than experiment may be partly due to the increase of pressure and partly to the structural phase change

  6. Electronic metal-support interaction enhanced oxygen reduction activity and stability of boron carbide supported platinum.

    Science.gov (United States)

    Jackson, Colleen; Smith, Graham T; Inwood, David W; Leach, Andrew S; Whalley, Penny S; Callisti, Mauro; Polcar, Tomas; Russell, Andrea E; Levecque, Pieter; Kramer, Denis

    2017-06-22

    Catalysing the reduction of oxygen in acidic media is a standing challenge. Although activity of platinum, the most active metal, can be substantially improved by alloying, alloy stability remains a concern. Here we report that platinum nanoparticles supported on graphite-rich boron carbide show a 50-100% increase in activity in acidic media and improved cycle stability compared to commercial carbon supported platinum nanoparticles. Transmission electron microscopy and x-ray absorption fine structure analysis confirm similar platinum nanoparticle shapes, sizes, lattice parameters, and cluster packing on both supports, while x-ray photoelectron and absorption spectroscopy demonstrate a change in electronic structure. This shows that purely electronic metal-support interactions can significantly improve oxygen reduction activity without inducing shape, alloying or strain effects and without compromising stability. Optimizing the electronic interaction between the catalyst and support is, therefore, a promising approach for advanced electrocatalysts where optimizing the catalytic nanoparticles themselves is constrained by other concerns.

  7. Thermodynamic and kinetic analysis of solid-phase interaction of alkali metal carbonates with arsenic pentoxide

    International Nuclear Information System (INIS)

    Pashinkin, A.S.; Buketov, E.A.; Isabaeva, S.M.; Kasenov, B.K.

    1985-01-01

    The thermodynamic analysis of solid-phase reactions of alkali metal carbonates with arsenic pentoxide showing the possibility of formation of all arsenates at a higher than the room temperature is performed. Energetically most advantageous is formation of meta-arsenates. It is shown that temperature increase favours the reaction process. By Gibbs standard energy decrease the reactions form the Li>Na>K>Rb>Cs series. On the base of calculation data linear dependence of Gibbs standard energy in reactions on the atomic number of alkali metalis established. By the continuous weighing method the kinetics of interaction of alkali metal carbonates with arsenic pentoxide under isothermal conditions in the 450-500 deg C range is studied. Studies is the dependence of apparent energy of interaction of carbonates wih As 2 0 5 an atomic parameters of al

  8. Modelling metal-humate interactions: an approach based on the Gibbs-Donnan concept

    International Nuclear Information System (INIS)

    Ephraim, J.H.

    1995-01-01

    Humic and fulvic acids constitute an appreciable portion of organic substances in both aquatic and terrestrial environments. Their ability to sequester metal ions and other trace elements has engaged the interest of numerous environmental scientists recently and even though considerable advances have been made, a lot more remains unknown in the area. The existence of high molecular weight fractions and functional group heterogeneity have endowed ion exchange characteristics to these substances. For example, the cation exchange capacities of some humic substances have been compared to those of smectites. Recent development in the solution chemistry has also indicated that humic substances have the capability to interact with other anions because of their amphiphilic nature. In this paper, metal-humate interaction is described by relying heavily on information obtained from treatment of the solution chemistry of ion exchangers as typical polymers. In such a treatment, the perturbations to the metal-humate interaction are estimated by resort to the Gibbs-Donnan concept where the humic substance molecule is envisaged as having a potential counter-ion concentrating region around its molecular domain into which diffusible components can enter or leave depending on their corresponding electrochemical potentials. Information from studies with ion exchangers have been adapted to describe ionic equilibria involving these substances by making it possible to characterise the configuration/conformation of these natural organic acids and to correct for electrostatic effects in the metal-humate interaction. The resultant unified physicochemical approach has facilitated the identification and estimation of the complications to the solution chemistry of humic substances. (authors). 15 refs., 1 fig

  9. Interaction between a bubble and a metal target for underwater laser propulsion.

    Science.gov (United States)

    Qiang, Hao; Chen, Jun; Han, Bing; Pan, Yunxiang; Zhang, Hongchao; Shen, Zhonghua; Lu, Jian; Ni, Xiaowu

    2017-04-10

    Optical beam deflection and high-speed photographic methods are employed to investigate the interaction mechanism between a laser-induced bubble and a metal target for underwater laser propulsion. A preliminary theory is proposed to reveal the step increases of the kinetic energy transferred to the target during the process of increasing the incident laser energy. This theory also helps to explain the increasing coupling efficiency with incident laser energy for underwater laser propulsion.

  10. Contribution to the theoretical study of metallic systems containing rare earths: hyperfine interactions and exchange coupling

    International Nuclear Information System (INIS)

    Troper, A.

    1978-01-01

    A theoretical study involving rare earth impurities, which were embedded in transition metals (s-p or noble), from the point of view of the hyperfine interactions is presented. A model was created to describe a d-resonance (Anderson-Moriya) acting on a s-p conduction band which was strongly perturbed by a slater-koster potential, used to describe the rare earths which were diluted in matrices of transition elements. (author)

  11. TOWARD TUNGSTEN PLASMA-FACING COMPONENTS IN KSTAR: RESEARCH ON PLASMA-METAL WALL INTERACTION

    Czech Academy of Sciences Publication Activity Database

    Hong, S.-H.; Kim, K.M.; Song, J.-H.; Bang, E.-N.; Kim, H.-T.; Lee, K.-S.; Litnovsky, A.; Hellwig, M.; Seo, D.C.; Lee, H.H.; Kang, C.S.; Lee, H.-Y.; Hong, J.-H.; Bak, J.-G.; Kim, H.-S.; Juhn, J.-W.; Son, S.-H.; Kim, H.-K.; Douai, D.; Grisolia, C.; Wu, J.; Luo, G.-N.; Choe, W.-H.; Komm, Michael; van den Berg, M.; De Temmerman, G.; Pitts, R.

    2015-01-01

    Roč. 68, č. 1 (2015), s. 36-43 ISSN 1536-1055. [International Conference on Open Magnetic Systems for Plasma Confinement (OS 2014)/10./. Daejeon, 26.08.2014-29.08.2014] Institutional support: RVO:61389021 Keywords : Plasma-metal wall interaction * Tungsten technology Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 0.799, year: 2015 http://dx.doi.org/10.13182/FST14-897

  12. Screened Coulomb interactions in metallic alloys. I. Universal screening in the atomic-sphere approximation

    DEFF Research Database (Denmark)

    Ruban, Andrei; Skriver, Hans Lomholt

    2002-01-01

    We have used the locally self-consistent Green's-function (LSGF) method in supercell calculations to establish the distribution of the net charges assigned to the atomic spheres of the alloy components in metallic alloys with different compositions and degrees of order. This allows us to determine......-site local interaction zone. We demonstrate that the basic mechanism that governs the charge distribution is the screening of the net charges of the alloy components that makes the direct Coulomb interactions short ranged. In the atomic-sphere approximation, this screening appears to be almost independent...

  13. Toxicological interactions of silver nanoparticles and non-essential metals in human hepatocarcinoma cell line.

    Science.gov (United States)

    Miranda, Renata Rank; Bezerra, Arandi Ginane; Oliveira Ribeiro, Ciro Alberto; Randi, Marco Antônio Ferreira; Voigt, Carmen Lúcia; Skytte, Lilian; Rasmussen, Kaare Lund; Kjeldsen, Frank; Filipak Neto, Francisco

    2017-04-01

    Toxicological interaction represents a challenge to toxicology, particularly for novel contaminants. There are no data whether silver nanoparticles (AgNPs), present in a wide variety of products, can interact and modulate the toxicity of ubiquitous contaminants, such as nonessential metals. In the current study, we investigated the toxicological interactions of AgNP (size=1-2nm; zeta potential=-23mV), cadmium and mercury in human hepatoma HepG2 cells. The results indicated that the co-exposures led to toxicological interactions, with AgNP+Cd being more toxic than AgNP+Hg. Early (2-4h) increases of ROS (DCF assay) and mitochondrial O 2 - levels (Mitosox® assay) were observed in the cells co-exposed to AgNP+Cd/Hg, in comparison to control and individual contaminants, but the effect was partially reverted in AgNP+Hg at the end of 24h-exposure. In addition, decreases of mitochondrial metabolism (MTT), cell viability (neutral red uptake assay), cell proliferation (crystal violet assay) and ABC-transporters activity (rhodamine accumulation assay) were also more pronounced in the co-exposure groups. Foremost, co-exposure to AgNP and metals potentiated cell death (mainly by necrosis) and Hg 2+ (but not Cd 2+ ) intracellular levels (ICP-MS). Therefore, toxicological interactions seem to increase the toxicity of AgNP, cadmium and mercury. Copyright © 2017 Elsevier Ltd. All rights reserved.

  14. Interfacial interactions between Skeletonema costatum extracellular organic matter and metal oxides: Implications for ceramic membrane filtration

    KAUST Repository

    Zaouri, Noor A

    2017-03-21

    In the current study, the interfacial interactions between the high molecular weight (HMW) compounds of Skeletonema costatum (SKC) extracellular organic matter (EOM) and ZrO2 or Al2O3, were investigated by atomic force microscopy (AFM). HMW SKC-EOM was rigorously characterized and described as a hydrophilic organic compound mainly comprised of polysaccharide-like structures. Lipids and proteins were also observed, although in lower abundance. HMW SKC-EOM displayed attractive forces during approaching (i.e., leading to jump-to-contact events) and adhesion forces during retracting regime to both metal oxides at all solution conditions tested, where electrostatics and hydrogen bonding were suggested as dominant interacting mechanisms. However, the magnitude of these forces was significantly higher on ZrO2 surfaces, irrespective of cation type (Na+ or Ca2+) or concentration. Interestingly, while HMW SKC-EOM interacting forces to Al2O3 were practically insensitive to solution chemistry, the interactions between ZrO2 and HMW SKC-EOM increased with increasing cation concentration in solution. The structure, and lower charge, hydrophilicity, and density of hydroxyl groups on ZrO2 surface would play a key role on favoring zirconia associations with HMW SKC-EOM. The current results contribute to advance our fundamental understanding of Algogenic Organic Matter (AOM) interfacial interactions with metal oxides (i.e., AOM membrane fouling), and would highly assist in the proper selection of membrane material during episodic algal blooms.

  15. Humic acid metal cation interaction studied by spectromicroscopy techniques in combination with quantum chemical calculations.

    Science.gov (United States)

    Plaschke, M; Rothe, J; Armbruster, M K; Denecke, M A; Naber, A; Geckeis, H

    2010-03-01

    Humic acids (HA) have a high binding capacity towards traces of toxic metal cations, thus affecting their transport in aquatic systems. Eu(III)-HA aggregates are studied by synchrotron-based scanning transmission X-ray microscopy (STXM) at the carbon K-edge and laser scanning luminescence microscopy (LSLM) at the (5)D(0) --> (7)F(1,2) fluorescence emission lines. Both methods provide the necessary spatial resolution in the sub-micrometre range to resolve characteristic aggregate morphologies: optically dense zones embedded in a matrix of less dense material in STXM images correspond to areas with increased Eu(III) luminescence yield in the LSLM micrographs. In the C 1s-NEXAFS of metal-loaded polyacrylic acid (PAA), used as a HA model compound, a distinct complexation effect is identified. This effect is similar to trends observed in the dense fraction of HA/metal cation aggregates. The strongest complexation effect is observed for the Zr(IV)-HA/PAA system. This effect is confirmed by quantum chemical calculations performed at the ab initio level for model complexes with different metal centres and complex geometries. Without the high spatial resolution of STXM and LSLM and without the combination of molecular modelling with experimental results, the different zones indicating a ;pseudo'-phase separation into strong complexing domains and weaker complexing domains of HA would never have been identified. This type of strategy can be used to study metal interaction with other organic material.

  16. Interaction of concretes with oxide + metal corium. The VULCANO VBS series

    International Nuclear Information System (INIS)

    Journeau, Christophe; Bonnet, Jean-Michel; Ferry, Lionel; Haquet, Jean-Francois; Piluso, Pascal

    2009-01-01

    In the hypothetical case of a severe accident, the reactor core could melt and the formed mixture, called corium, could melt through the vessel and interact with the reactor pit concrete. Corium is made from a UO 2 -rich oxidic part, in which most of the decay heat is dissipated, and a metallic part, mainly molten steel. Up to now, due to experimental constraints, most of the experiments have been performed with solely oxidic prototypic corium, or where designed so that most of the simulated decay heat was dissipated in the metallic layer. An experimental program has been set up in the VULCANO facility in which oxidic and metallic mixtures are melted in separate furnaces and poured in a concrete cavity. Induction heating is provided to the pool upper part thanks to shielding coils, so that, in case of stratification, the lighter oxidic corium-concrete mixture receives most of the power. Three experiments have been conducted: one with a limestone-rich concrete and two with a silica-rich concrete. Metal stratification has been determined from modifications of the corium electrical properties in front of the inductor and is in good accordance with calculations. Concrete ablation has been monitored. A significant vertical ablation has been observed, even in case of silica-rich concretes, for which largely radial ablation has been observed in the case of pure oxidic corium melts. Post Test Examinations have shown unexpected repartitions of metal in the pool. (author)

  17. Interaction between dental metals and antioxidants, assessed by cytotoxicity assay and ESR spectroscopy.

    Science.gov (United States)

    Kinoshita, Naoto; Yamamura, Takahiko; Teranuma, Hiroshi; Katayama, Tadashi; Tamanyu, Mikako; Negoro, Takaharu; Satoh, Kazue; Sakagami, Hiroshi

    2002-01-01

    Among dental metals, copper showed the highest cytotoxicity against human oral squamous cell carcinoma and human submandibular gland carcinoma cells, followed by palladium-alloy, gold and silver. Normal human cells (gingival fibroblast, pulp cells, periodontal ligament fibroblast) were relatively resistant to these metals. The palladium-alloy failed to induce internucleosomal DNA fragmentation, a biochemical hallmark of apoptosis, in human promyelocytic leukemic HL-60 cells. The cytotoxic activity of the palladium-alloy was significantly reduced by a non-cytotoxic concentration of N-acetyl-L-cysteine, or more efficiently by sodium ascorbate. However, higher concentrations of sodium ascorbate enhanced the cytotoxic activity of palladium-alloy. ESR spectroscopy showed that the palladium-alloy enhanced the intensity of ascorbate radical, suggesting the possible interaction between metals and antioxidants. All metals, except copper, did not significantly affect the generation of superoxide anion (by hypoxanthine-xanthine oxidase reaction), hydroxyl radical (by Fenton reaction) and nitric oxide (from NOC-7 in the presence of C-PTIO). These data demonstrate for the first time that antioxidants modify the biological activity of dental metals.

  18. Metal accumulation in the polychaete Hediste japonica with emphasis on interaction between heavy metals and petroleum hydrocarbons

    International Nuclear Information System (INIS)

    Sun Fuhong; Zhou Qixing

    2007-01-01

    The accumulation of cadmium (Cd) and copper (Cu) in the polychaete Hediste japonica exposed to the mixture of Cd (or Cu) and petroleum hydrocarbons (PHCs) was investigated and compared with that exposed to single Cd (or Cu). The increased bioavailability of Cd or Cu with exposure concentrations resulted in an increase in the accumulation and net accumulation rate of Cd or Cu during single metal exposure. The net accumulation rate of Cd increased, but the net accumulation rate of Cu decreased with exposure time during single metal exposure, suggesting that H. japonica could actively regulate Cu burden in their body by inhibition of absolute uptake or promotion of excretion. The interactions between Cd (or Cu) and PHCs had complicated influences on the net accumulation rate of Cd and Cu in H. japonica under the condition of the binary mixture, which are dependent on their concentration combinations and exposure time. - The influences of petroleum hydrocarbons on Cd and Cu accumulation in H. japonica depend on their concentration combinations and exposure time

  19. Mechanisms governing the interaction of metallic particles with nanosecond laser pulses.

    Science.gov (United States)

    Demos, Stavros G; Negres, Raluca A; Raman, Rajesh N; Shen, Nan; Rubenchik, Alexander M; Matthews, Manyalibo J

    2016-04-04

    The interaction of nanosecond laser pulses at 1064- and 355-nm with micro-scale, nominally spherical metallic particles is investigated in order to elucidate the governing interaction mechanisms as a function of material and laser parameters. The experimental model used involves the irradiation of metal particles located on the surface of transparent plates combined with time-resolved imaging capable of capturing the dynamics of particle ejection, plume formation and expansion along with the kinetics of the dispersed material from the liquefied layer of the particle. The mechanisms investigated in this work are informative and relevant across a multitude of materials and irradiation geometries suitable for the description of a wide range of specific applications. The experimental results were interpreted using physical models incorporating specific processes to assess their contribution to the overall observed behaviors. Analysis of the experimental results suggests that the induced kinetic properties of the particle can be adequately described using the concept of momentum coupling introduced to explain the interaction of plane metal targets to large-aperture laser beams. The results also suggest that laser energy deposition on the formed plasma affects the energy partitioning and the material modifications to the substrate.

  20. Synthesis and characterizations of ultra-small ZnS and Zn(1-x)Fe(x)S quantum dots in aqueous media and spectroscopic study of their interactions with bovine serum albumin.

    Science.gov (United States)

    Khani, Omid; Rajabi, Hamid Reza; Yousefi, Mohammad Hasan; Khosravi, Ali Azam; Jannesari, Mohammad; Shamsipur, Mojtaba

    2011-07-01

    This work reports a new experimental methodology for the synthesis of ultra small zinc sulfide and iron doped zinc sulfide quantum dots in aqueous media. The nanoparticles were obtained using a simple procedure based on the precipitation of ZnS in aqueous solution in the presence of 2-mercaptoethanol as a capping agent, at room temperature. The effect of Fe(3+) ion concentration as dopant on the optical properties of ZnS was studied. The size of quantum dots was determined to be about 1nm, using scanning tunneling microscopy. The synthesized nanoparticles were characterized by X-ray diffraction, UV-Vis absorption and photoluminescence emission spectroscopies. The presence and amount of iron impurity in the structure of Zn((1-x))Fe(x)S nanocrystals were confirmed by atomic absorption spectrometry. A blue shift in band-gap of ZnS was observed upon increasing incorporation of Fe(3+) ion in the iron doped zinc sulfide quantum dots. The photoluminescence investigations showed that, in the case of iron doped ZnS nanoparticles, the emission band of pure ZnS nanoparticles at 427nm shifts to 442nm with appearance of a new sharp emission band around 532nm. The X-ray diffraction analysis indicated that the iron doped nanoparticles are crystalline, with cubic zinc blend structure, having particle diameters of 1.7±022nm. Finally, the interaction of the synthesized nanoparticles with bovine serum albumin was investigated at pH 7.2. The UV-Vis absorption and fluorescence spectroscopic methods were applied to compare the optical properties of pure and iron doped ZnS quantum dots upon interaction with BSA. It was proved that, in both cases, the fluorescence quenching of BSA by the quantum dots is mainly a result of the formation of QDs-BSA complex in solution. In the steady-state fluorescence studies, the interaction parameters including binding constants (K(a)), number of binding sites (n), quenching constants ( [Formula: see text] ), and bimolecular quenching rate constants (k

  1. Novel Transgenic Mouse Model for Studying Human Serum Albumin as a Biomarker of Carcinogenic Exposure.

    Science.gov (United States)

    Sheng, Jonathan; Wang, Yi; Turesky, Robert J; Kluetzman, Kerri; Zhang, Qing-Yu; Ding, Xinxin

    2016-05-16

    Albumin is a commonly used serum protein for studying human exposure to xenobiotic compounds, including therapeutics and environmental pollutants. Often, the reactivity of albumin with xenobiotic compounds is studied ex vivo with human albumin or plasma/serum samples. Some studies have characterized the reactivity of albumin with chemicals in rodent models; however, differences between the orthologous peptide sequences of human and rodent albumins can result in the formation of different types of chemical-protein adducts with different interaction sites or peptide sequences. Our goal is to generate a human albumin transgenic mouse model that can be used to establish human protein biomarkers of exposure to hazardous xenobiotics for human risk assessment via animal studies. We have developed a human albumin transgenic mouse model and characterized the genotype and phenotype of the transgenic mice. The presence of the human albumin gene in the genome of the model mouse was confirmed by genomic PCR analysis, whereas liver-specific expression of the transgenic human albumin mRNA was validated by RT-PCR analysis. Further immunoblot and mass spectrometry analyses indicated that the transgenic human albumin protein is a full-length, mature protein, which is less abundant than the endogenous mouse albumin that coexists in the serum of the transgenic mouse. The transgenic protein was able to form ex vivo adducts with a genotoxic metabolite of 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine, a procarcinogenic heterocyclic aromatic amine formed in cooked meat. This novel human albumin transgenic mouse model will facilitate the development and validation of albumin-carcinogen adducts as biomarkers of xenobiotic exposure and/or toxicity in humans.

  2. Cellular specificity of the blood-CSF barrier for albumin transfer across the choroid plexus epithelium.

    Directory of Open Access Journals (Sweden)

    Shane A Liddelow

    Full Text Available To maintain the precise internal milieu of the mammalian central nervous system, well-controlled transfer of molecules from periphery into brain is required. Recently the soluble and cell-surface albumin-binding glycoprotein SPARC (secreted protein acidic and rich in cysteine has been implicated in albumin transport into developing brain, however the exact mechanism remains unknown. We postulate that SPARC is a docking site for albumin, mediating its uptake and transfer by choroid plexus epithelial cells from blood into cerebrospinal fluid (CSF. We used in vivo physiological measurements of transfer of endogenous (mouse and exogenous (human albumins, in situ Proximity Ligation Assay (in situ PLA, and qRT-PCR experiments to examine the cellular mechanism mediating protein transfer across the blood-CSF interface. We report that at all developmental stages mouse albumin and SPARC gave positive signals with in situ PLAs in plasma, CSF and within individual plexus cells suggesting a possible molecular interaction. In contrast, in situ PLA experiments in brain sections from mice injected with human albumin showed positive signals for human albumin in the vascular compartment that were only rarely identifiable within choroid plexus cells and only at older ages. Concentrations of both endogenous mouse albumin and exogenous (intraperitoneally injected human albumin were estimated in plasma and CSF and expressed as CSF/plasma concentration ratios. Human albumin was not transferred through the mouse blood-CSF barrier to the same extent as endogenous mouse albumin, confirming results from in situ PLA. During postnatal development Sparc gene expression was higher in early postnatal ages than in the adult and changed in response to altered levels of albumin in blood plasma in a differential and developmentally regulated manner. Here we propose a possible cellular route and mechanism by which albumin is transferred from blood into CSF across a sub

  3. Study by nuclear techniques of the impurity-defect interaction in implanted metals<