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Sample records for denaturing sodium dodecyl

  1. Evidence of β-sheet structure induced kinetic stability of papain upon thermal and sodium dodecyl sulphate denaturation

    Directory of Open Access Journals (Sweden)

    Rašković Brankica

    2015-01-01

    Full Text Available Papain is a protease that consists of α-helical and β-sheet domains which unfold almost independently. Both, papain considerable thermal stability and sodium dodecyl sulphate (SDS resistance have been shown. However, the ability of each domain to unfold upon thermal and SDS denaturation has never been studied. This work shows that fruit papain has slightly higher thermal inactivation resistance when it is compared to stem papain with rather high activation energy (Ea of 223 ± 16 kJmol-1 and Tm50 value of 79 ± 2 °C. SDS resistance of fruit papain was estimated by SDS-PAGE analysis and activity staining. It has been noted that, in the presence of SDS, unless heat energy was applied in order to unfold papain, the protein remained active. Furthermore, it has been proven via Fourier transform infrared spectroscopy (FT-IR that α-helical domain of fruit papain is more prone to unfolding at elevated temperatures and in the presence of SDS then β-sheet rich domain. Thermal denaturation of papain without detergent present led to accelerated formation of aggregation specific intermolecular β-sheets as compared to native protein. Presented results are both, of fundamental and application importance. [Projekat Ministarstva nauke Republike Srbije, br. 172049

  2. Surface and thermodynamic properties of sodium dodecyl sulphate and sodium dodecyl sulphonate

    Energy Technology Data Exchange (ETDEWEB)

    Janczuk, B. [Dept. de Fisica, Facultad de Ciencias, Univ. de Extremadura, Badajoz (Spain); Gonzalez-Martin, M.L. [Dept. de Fisica, Facultad de Ciencias, Univ. de Extremadura, Badajoz (Spain); Bruque, J.M. [Dept. de Fisica, Facultad de Ciencias, Univ. de Extremadura, Badajoz (Spain); Dorado-Calasanz, C. [Dept. de Fisica, Facultad de Ciencias, Univ. de Extremadura, Badajoz (Spain)

    1996-09-01

    Determinations of the surface tension of aqueous solutions of sodium dodecyl sulphate and sodium dodecyl sulphonate were made in the presence of a neutral salt (NaCl; 0.1 M) at 20 C. On the basis of these determinations the isotherms and the standard thermodynamic parameters of adsorption were determined. The equation of state for a monolayer film of the studied surfactants was also discussed. A linear dependence was found between log {Gamma} and log c in the range of low surfactant concentrations. The limiting value of {Pi} (A-A{sub 0}) was found to be 1 kT in contrary to the case in which the solutions were made in the absence of neutral salt. It has been suggested that there are not only attractive forces of the Lifshitz-van der Waals type but also acid-base forces which can affect the {Pi} parameter. (orig.) [Deutsch] Die Grenzflaechenspannung waessriger Loesungen von Natriumdodecylsulfat und Natriumdodecylsulfonat bei 20 C in Gegenwart eines Neutralsalzes (0,1 M NaCl) wurde bestimmt. Auf der Grundlage dieser Messungen wurden die Isothermen und die thermodynamischen Standardgroessen der Adsorption ermittelt. Die Zustandsgleichung fuer einen monomolekularen Film der untersuchten Tenside wird diskutiert. Es wurde eine lineare Beziehung zwischen log {Gamma} und log c fuer niedrige Tensidkonzentrationen gefunden. Ferner wurde festgestellt, dass der Grenzwert von {Pi} (A-A{sub 0}) in den Loesungen gleich 1 kT ist, anders als bei Abwesenheit eines Neutralsalzes. Daraus wurde geschlossen, dass nicht nur Anziehungskraefte des Lifshitz-van der Waals-Typs vorliegen, sondern auch Saeure-Base-Kraefte, die die {Pi}-Parameter beeinflussen koennen. (orig.)

  3. Phase Behavior and Structural Transitions in Sodium Dodecyl Sulfonate Microemulsions

    Institute of Scientific and Technical Information of China (English)

    杨根生; 施介华; 等

    2002-01-01

    The forming mechanism of microemulsion of sodium dodecyl sulfonate.alcohols,water and isooctane was studied,with particular emphasis on the effect of molecular weight and concentration of alocohols.Phase diagram of the four components,alcohol, sodium dodecyl sulfonate,water and isooctane,was used as a means of study,through which the microemulsion regions were determined.Phase diagram of sodium dodecyl sulfonate/n-pentanol/isooctane/water system at km=2(km=Wn-pentanol/WSDS)is presented. The variation of conductivities of different microemulsion samples with water was measured.From the conductivities we investigated a change in structure from water droplets in oil(W/O)at low water content to liquid crystal at intermediate water content and a structure of oil droplets in water(O/W)at high water content.

  4. Anaerobic degradation of sodium dodecyl sulfate (SDS) by denitrifying bacteria

    NARCIS (Netherlands)

    Paulo, A.; Plugge, C.M.; Garcia Encina, P.A.; Stams, A.J.M.

    2013-01-01

    Two denitrifying bacteria were isolated using sodium dodecyl sulfate (SDS) as substrate. Strains SN1 and SN2 were isolated from an activated sludge reactor of a wastewater treatment plant (WWTP) with Anaerobic–Anoxic–Oxic (A2/O) steps. Based on 16S rRNA gene analysis strain SN1 is 99% similar to Pse

  5. Anaerobic degradation of sodium dodecyl sulfate (SDS) by denitrifying bacteria

    NARCIS (Netherlands)

    Paulo, A.; Plugge, C.M.; Garcia Encina, P.A.; Stams, A.J.M.

    2013-01-01

    Two denitrifying bacteria were isolated using sodium dodecyl sulfate (SDS) as substrate. Strains SN1 and SN2 were isolated from an activated sludge reactor of a wastewater treatment plant (WWTP) with Anaerobic–Anoxic–Oxic (A2/O) steps. Based on 16S rRNA gene analysis strain SN1 is 99% similar to

  6. Green synthesis of gold nanoparticles reduced and stabilized by sodium glutamate and sodium dodecyl sulfate.

    Science.gov (United States)

    Cabrera, Gil Felicisimo S; Balbin, Michelle M; Eugenio, Paul John G; Zapanta, Charleo S; Monserate, Juvy J; Salazar, Joel R; Mingala, Claro N

    2017-03-18

    The Turkevich method has been used for many years in the synthesis of gold nanoparticles. Lately, the use of plant extracts and amino acids has been reported, which is valuable in the field of biotechnology and biomedicine. The AuNPs was synthesized from the reduction of HAuCl4 3H2O by sodium glutamate and stabilized with sodium dodecyl sulfate. The optimum concentrations for sodium glutamate and sodium dodecyl sulfate in the synthesis process were determined. The characteristics of the synthesized AuNPs was analysed through UV-Vis Spectroscopy and SEM. The AuNPs have spherical shape with a mean diameter of approximately 21.62 ± 4.39 nm and is well dispersed. FTIR analysis of the AuNPs reflected that the sulfate head group of sodium dodecyl sulfate is adsorbed at the surface of the AuNPs. Thus, we report herein the synthesis of AuNPs using sodium glutamate and sodium dodecyl sulfate. Copyright © 2017 Elsevier Inc. All rights reserved.

  7. Estimation of interfacial acidity of sodium dodecyl sulfate micelles

    Indian Academy of Sciences (India)

    Arghya Dey; G Naresh Patwari

    2011-11-01

    An enhancement in the excited state proton transfer (ESPT) processes of coumarin-102 (C-102) dye was observed upon addition of salicylic acid and hydrochloric acid in sodium dodecyl sulfate (SDS) micellar solution. The phenomenon was observed only in the micellar medium of anionic surfactant SDS and not in case of cationic (CTAB) or neutral (Trition X -100) surfactants. ESPT of C-102 was also observed in aqueous solutions but on addition of very high concentrations of hydrochloric acid. However, on comparing the ratio of the protonated species from the emission spectra in the presence and absence of SDS micelle, a conclusive estimation of the local proton concentration at the Stern layer of SDS micelles could be evaluated.

  8. Ionic quenching of naphthalene fluorescence in sodium dodecyl sulfate micelles.

    Science.gov (United States)

    Silva, Alessandra F; Fiedler, Haidi D; Nome, Faruk

    2011-03-31

    Micellar effects on luminescense of organic compounds or probes are well established, and here we show that quenching is highly favored in aqueous sodium dodecyl sulfate (SDS) micelles, which concentrate a naphthalene probe and cations of lanthanides, transition metals, and noble metals. Interactions have been studied by steady state and time-resolved fluorescence in examining the fluorescence suppression of naphthalene by metal ions in anionic SDS micelles. The quenching is collisional and correlated with the unit charge and the reduction potential of the metal ion. The rate constants, calculated in terms of local metal ion concentrations, are close to the diffusion control limit in the interior of SDS micelles, where the microscopic viscosity decreases the transfer rate, following the Stokes-Einstein relation.

  9. Complexation between sodium dodecyl sulfate and amphoteric polyurethane nanoparticles.

    Science.gov (United States)

    Qiao, Yong; Zhang, Shifeng; Lin, Ouya; Deng, Liandong; Dong, Anjie

    2007-09-27

    The complexation between negatively charged sodium dodecyl sulfate (SDS) and positively charged amphoteric polyurethane (APU) self-assembled nanoparticles (NPs) containing nonionic hydrophobic segments is studied by dynamic light scattering, pyrene fluorescent probing, zeta-potential, and transmission electron microscopy (TEM) in the present paper. With increasing the mol ratio of SDS to the positive charges on the surface of APU NPs, the aqueous solution of APU NPs presents precipitation at pH 2, around stoichiometric SDS concentration, and then the precipitate dissociates with excess SDS to form more stable nanoparticles of ionomer complexes. Three stages of the complexation process are clearly shown by the pyrene I1/I3 variation of the complex systems, which only depends on the ratio of SDS/APU, and demonstrate that the process is dominated by electrostatic attraction and hydrophobic aggregation.

  10. Location of ethanol in sodium dodecyl sulfate aggregates

    Institute of Scientific and Technical Information of China (English)

    LIU, Tian-Qing; YU, Wei-Li; GUO, Rong

    2000-01-01

    The hexagonal liquid crystalline phase of SDS ( Sodium dodecyl sulfate)/H2O system changes into lamellar liquid crystal and the effective length of surfactant molecule d0/2 in the lamellar liquid crystal decreases with the addition of ethanol.The micellar aggregation number N of SDS decreases and the micellar diffusion coefficient increases with the added ethanol.Under a constant concentration of SDS, the molecule number ratio of ethanol to SDS in the micelle increases with the concentration of ethanol and even exceeds 10 when ethanol concentration is 1.085 mol/L. All these results show that ethanol, even though a short chain alcohol and soluble in water, can partly exist in the interphase of the amphiphilic aggregates showing some properties of co-surfactant.

  11. Sodium dodecyl sulfate-induced rapid gelation of silk fibroin.

    Science.gov (United States)

    Wu, Xilong; Hou, Jing; Li, Mingzhong; Wang, Jiangnan; Kaplan, David L; Lu, Shenzhou

    2012-07-01

    The in situ formation of injectable silk fibroin (SF) hydrogels have potential advantages over various other biomaterials due to the minimal invasiveness during application. Biomaterials need to gel rapidly under physiological conditions after injection. In the current paper, a novel way to accelerate SF gelation using an anionic surfactant, sodium dodecyl sulfate (SDS), as a gelling agent is reported. The mechanism of SDS-induced rapid gelation was determined. At low surfactant concentrations, hydrophobic interactions among the SF chains played a dominant role in the association, leading to decreased gelation time. At higher concentrations of surfactant, electrostatic repulsive forces among micellar aggregates gradually became dominant and gelation was hindered. Gel formation involves the connection of clusters formed by the accumulation of nanoparticles. This process is accompanied by the rapid formation of β-sheet structures due to hydrophobic and electrostatic interactions. It is expected that the silk hydrogel with short gelation time will be used as an injectable hydrogel in drug delivery or cartilage tissue engineering.

  12. On the Effect of Sodium Chloride and Sodium Sulfate on Cold Denaturation.

    Directory of Open Access Journals (Sweden)

    Andrea Pica

    Full Text Available Both sodium chloride and sodium sulfate are able to stabilize yeast frataxin, causing an overall increase of its thermodynamic stability curve, with a decrease in the cold denaturation temperature and an increase in the hot denaturation one. The influence of low concentrations of these two salts on yeast frataxin stability can be assessed by the application of a theoretical model based on scaled particle theory. First developed to figure out the mechanism underlying cold denaturation in water, this model is able to predict the stabilization of globular proteins provided by these two salts. The densities of the salt solutions and their temperature dependence play a fundamental role.

  13. Sodium Dodecyl Sulfate (SDS)-Loaded Nanoporous Polymer as Anti-Biofilm Surface Coating Material

    DEFF Research Database (Denmark)

    Li, Li; Molin, Søren; Yang, Liang

    2013-01-01

    -b-polydimethylsiloxane (1,2-PB-b-PDMS) block copolymer via chemical cross-linking of the 1,2-PB block followed by quantitative removal of the PDMS block. Sodium dodecyl sulfate (SDS) was loaded into the nanoporous 1,2-PB from aqueous solution. The SDS-loaded nanoporous polymer films were shown to block bacterial attachment...

  14. Thermodynamics of Sodium Dodecyl Sulfate (SDS) Micellization: An Undergraduate Laboratory Experiment

    Science.gov (United States)

    Marcolongo, Juan P.; Mirenda, Martin

    2011-01-01

    An undergraduate laboratory experiment is presented that allows a thermodynamic characterization of micelle formation of sodium dodecyl sulfate (SDS) in aqueous solutions. The critical micelle concentration (CMC) and the degree of micelle ionization (alpha) are obtained at different temperatures by conductimetry. The molar standard free energy…

  15. The Electrooxidation of Tetracycline at Acetylene Black Electrode in the Presence of Sodium Dodecyl Sulfate

    Institute of Scientific and Technical Information of China (English)

    Xue Ping DANG; Cheng Guo HU; Ying Liang WEI; Sheng Shui HU

    2004-01-01

    The electrooxidation of tetracycline (TC) at acetylene black electrode has been studied in the presence of sodium dodecyl sulfate (SDS). Tetracycline (TC) exhibited very sensitive oxidation peak in this system. The peak current was proportional to TC concentration, and the detection limit was 1.2 × 10-8 mol/L. The system was used to the determination of TC in pharmaceuticals.

  16. CLONING AND SEQUENCING OF PSEUDOMONAS GENES DETERMINING SODIUM DODECYL-SULFATE BIODEGRADATION

    NARCIS (Netherlands)

    DAVISON, J; BRUNEL, F; PHANOPOULOS, A; PROZZI, D; TERPSTRA, P

    1992-01-01

    The nucleotide sequences of two genes involved in sodium dodecyl sulfate (SDS) degradation, by Pseudomonas, have been determined. One of these, sdsA, codes for an alkyl sulfatase (58 957 Da) and has similarity (31.8% identity over a 201-amino acid stretch) to the N terminus of a predicted protein of

  17. The effects of deoxycholate and sodium dodecyl sulphate on the serological reactivity of antigens isolated from six Bacteroides reference strains

    NARCIS (Netherlands)

    I. Beckmann (Ilse); F. Meisel-Mikolajczyk; H.C.S. Wallenburg (Henk)

    1990-01-01

    markdownabstractAbstract The detergents sodium dodecyl sulphate (SDS) and sodium deoxycholate (NaD) are frequently used as solvents for macromolecular polysaccharide complexes in immunochemical and serological techniques. The influence of the disaggregating surfactants on the serological reactivit

  18. The effects of deoxycholate and sodium dodecyl sulphate on the serological reactivity of antigens isolated from six Bacteroides reference strains

    NARCIS (Netherlands)

    I. Beckmann (Ilse); F. Meisel-Mikolajczyk; H.C.S. Wallenburg (Henk)

    1990-01-01

    markdownabstractAbstract The detergents sodium dodecyl sulphate (SDS) and sodium deoxycholate (NaD) are frequently used as solvents for macromolecular polysaccharide complexes in immunochemical and serological techniques. The influence of the disaggregating surfactants on the serological

  19. Phospholipid containing mixed micelles. Characterization of diheptanoyl phosphatidylcholine (DHPC) and sodium dodecyl sulfate and DHPC and dodecyl trimethylammonium bromide.

    Science.gov (United States)

    Ranganathan, Radha; Vautier-Giongo, Carolina; Bakshi, Mandeep Singh; Bales, Barney L; Hajdu, Joseph

    2005-05-01

    Mixed micelles of l,2-diheptanoyl-sn-grycero-3-phosphocholine (DHPC) with ionic detergents were prepared to develop well characterized substrates for the study of lipolytic enzymes. The aggregates that formed on mixing DHPC with the anionic surfactant sodium dodecyl sulfate (SDS) and with the positively charged dodecyl trimethylammonium bromide (DTAB) were investigated using time-resolved fluorescence quenching (TRFQ) to determine the aggregation numbers and bimolecular collision rates, and electron spin resonance (ESR) to measure the hydration index and microviscosity of the micelles at the micelle-water interface. Mixed micelles between the phospholipid and each of the detergents formed in all compositions, yielding interfaces with varying charge, hydration, and microviscosity. Both series of micelles were found to be globular up to 0.7 mole fraction of DHPC, while the aggregation numbers varied within the same concentration range of the components less than 15%. Addition of the zwitterionic phospholipid component increased the degree of counterion dissociation as measured by the quenching of the fluorescence of pyrene by the bromide ions bound to DHPC/DTAB micelles, showing that at 0.6 mole fraction of DHPC 80% of the bromide ions are dissociated from the micelles. The interface water concentration decreased significantly on addition of DHPC to each detergent. For combined phospholipid and detergent concentration of 50 mM the interface water concentration decreased, as measured by ESR of the spin-probes, from 38.5 M/L of interface volume in SDS alone to 9 M/L when the phospholipid was present at 0.7 mole fraction. Similar addition of DHPC to DTAB decreased the interfacial water concentration from 27 M/L to 11 M/L. Determination of the physicochemical parameters of the phospholipid containing mixed micelles here presented are likely to provide important insight into the design of assay systems for kinetic studies of phospholipid metabolizing enzymes.

  20. Comparative study on the mechanisms of rotavirus inactivation by sodium dodecyl sulfate and ethylenediaminetetraacetate

    Energy Technology Data Exchange (ETDEWEB)

    Ward, R.L. (Sandia Labs., Albuquerque, NM); Ashley, C.S.

    1980-06-01

    This report describes a comparative study on the effects of the anionic detergent sodium dodecyl sulfate and the chelating agent ethylenediaminetetraacetate on purified rotavirus SA-11 particles. Both chemicals readily inactivated rotavirus at quite low concentrations and under very mild conditions. In addition, both agents modified the viral capsid and prevented the adsorption of inactivated virions to cells. Capsid damage by ethylenediaminetetraacetate caused a shift in the densities of rotavirions from about l.35 to about 1.37 g/ml and a reduction in their sedimentation coefficients. Sodium dodcyl sulfate, on the other hand, did not detectably alter either of these physical properties of rotavirions. Both agents caused some alteration of the isoelectric points of the virions. Finally, analysis of rotavirus proteins showed that ethylenediaminetetraacetate caused the loss of two protein peaks from the electrophoretic pattern of virions but sodium dodecyl sulfate caused the loss of only one of these same protein peaks.

  1. Electrochemical Oxidation of L-Cysteine in Sodium Dodecyl Sulfate Admicelles

    Institute of Scientific and Technical Information of China (English)

    李中春; 刘天晴; 郭荣

    2005-01-01

    The electrochemical oxidation of L-cysteine can be catalyzed by sodium dodecyl sulfate (SDS) admicelles. The catalytic efficiency increases hardly when SDS concentration is lower than the critical admicelle concentration (CAC) and increases rapidly when SDS concentration is between CAC and the critical micelle concentration (CMC), but decreases when SDS concentration is higher than CMC. Both results of rate constant k0 and Gibbs free energy ΔGck accord with that of catalytic efficiency.

  2. Preparation and Catalytic Properties of Iron-Cerium Phosphates with Sodium Dodecyl Sulfate

    OpenAIRE

    Hiroaki Onoda; Takeshi Sakumura

    2012-01-01

    Iron phosphate was prepared from iron nitrate and phosphoric acid with sodium dodecyl sulfate at various stirring hours. The chemical composition of the obtained samples was estimated from ICP and XRD measurements. Particle shape and size distribution were observed by SEM images and laser diffraction/scattering methods. Further, the catalytic activity was studied with the decomposition of the complex between formaldehyde, ammonium acetate, and acetylacetone. The peaks of FePO4 were observed i...

  3. Small angle neutron scattering studies of mixed micelles of sodium cumene sulphonate with cetyl trimethylammonium bromide and sodium dodecyl sulphate

    Indian Academy of Sciences (India)

    K V Padalkar; V G Gaikar; V K Aswal

    2008-11-01

    The aqueous solutions of sodium cumene sulphonate (NaCS) and its mixtures with each of cetyl trimethylammonium bromide (CTAB) and sodium dodecyl sulphate (SDS) are characterized by small angle neutron scattering (SANS). NaCS when added to CTAB solution leads to the formation of long rod-shaped micelles with a dramatic increase in the CTAB aggregation number. Its addition to SDS on the other hand results in the formation of smaller mixed micelles where part of SDS molecules in the micelle is replaced by NaCS molecules.

  4. A comparison study between sodium dodecyl sulfate and sodium dodecyl sulfonate with respect to the thermodynamic properties, micellization, and interaction with poly(ethylene glycol) in aqueous solutions

    Energy Technology Data Exchange (ETDEWEB)

    Sadeghi, Rahmat, E-mail: rsadeghi@uok.ac.ir [Department of Chemistry, University of Kurdistan, Sanandaj (Iran, Islamic Republic of); Shahabi, Somayyeh [Department of Chemistry, University of Kurdistan, Sanandaj (Iran, Islamic Republic of)

    2011-09-15

    Graphical abstract: Apparent molar volume against molality: o, {center_dot}, and {Delta}, respectively in water, (1 and 4) wt% PEG solution at 293.15 K; x, {Delta}, and lozenge, respectively in water, (1 and 4) wt% PEG solution at 313.15 K. Research Highlights: > C{sub 12}H{sub 25}SO{sub 3}Na(SDSn) was seen to interact with PEG more weakly than C{sub 12}H{sub 25}SO{sub 4}Na(SDS). > The constraints on molecular mobility of SDS micelles are larger than those of SDSn. > Entropy change on micellization for SDSn is larger than those for SDS. > Micelle formation of SDS is less endothermic and more spontaneous than that of SDSn. > Micelles of SDS have smaller aggregation number than that of SDSn. - Abstract: The density, sound velocity, and conductivity measurements were performed on aqueous solutions of sodium dodecyl sulfate (C{sub 12}H{sub 25}SO{sub 4}Na) or sodium dodecyl sulfonate (C{sub 12}H{sub 25}SO{sub 3}Na) in the absence and presence of poly(ethylene glycol) (PEG) at different temperatures. Changes in the apparent molar volumes and isentropic compressibilities upon micellization were derived using a pseudophase-transition approach and the infinite dilution apparent molar properties of the monomer and micellar form of C{sub 12}H{sub 25}SO{sub 4}Na and C{sub 12}H{sub 25}SO{sub 3}Na were determined. Variations of the critical micelle concentrations (CMCs) of both surfactants in the solutions investigated with temperature were obtained from which thermodynamic parameters of micellization were estimated. It was found that at low temperature the micelle formation process is endothermic and therefore, this process must be entropically driven. However, upon increasing the temperature, the enthalpic factor becomes more significant and, at temperatures higher than 303.15 K the micellization is enthalpy driven. The interactions between C{sub 12}H{sub 25}SO{sub 4}Na/C{sub 12}H{sub 25}SO{sub 3}Na and PEG were studied and it was found that sodium alkyl sulfonates were seen

  5. Polarized synchronous light scattering characterization of the interaction of proteins with sodium dodecyl sulfonate

    Institute of Scientific and Technical Information of China (English)

    ZHAO XiaoHui; HUANG ChengZhi

    2007-01-01

    In acid buffer solution, proteins with positive charge can react with anion surfactant and result in a great enhancement of synchronous light scattering (SLS) signals. In this contribution, the correlative experiment was made to compare the interaction of human serum albumin (HAS) and immunoglobulin G (IgG) with sodium dodecyl sulfonate (SDS). Based on the measurements of the polarization light scattering signals, a new method of scattering polarization was constituted to distinguish these two interaction systems with molecular weight difference (HAS 66 kDa; IgG 150 kDa). The results were consistent with the data measured by dynamic light scattering (DLS) technique.

  6. Preparation of Barley Storage Protein, Hordein, for Analytical Sodium Dodecyl Sulfate-Polyacrylamide Gel Electrophoresis

    DEFF Research Database (Denmark)

    Doll, Hans; Andersen, Bente

    1981-01-01

    The extraction, reduction, and alkylation of barley hordein for routine electrophoresis in sodium dodecyl sulfate-polyacrylamide gels were studied to set up a simple preparation procedure giving well-resolved bands in the electrophoresis gel. Hordein was extracted from single crushed seeds or flour...... by aqueous 50% propan-2-ol containing a Tris-borate buffer, pH 8.6. The presence of the buffer facilitates the consecutive complete reduction of the extracted protein in the alcohol. Reduction and alkylation in the buffer containing propan-2-ol give sharper bands in the electrophoresis than reduction...

  7. Adsorption characteristics of zinc ions on sodium dodecyl sulfate in process of micellar-enhanced ultrafiltration

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    To separate zinc ions from aqueous solution efficiently, micellar-enhanced ultrafiltration(MEUF) of hollow ultrafiltration membrane was used with sodium dodecyl sulfate(SDS) as surfactant. The formation of micellar and the adsorption mechanism were investigated, including the influence of the ratio of SDS to zinc ions on the micelle quantity, the micelle ratio, the gross adsorptive capacity, the rejection of zinc ions and the adsorption isotherm law. The results show that the rejection rate of zinc ions reaches 97% and the adsorption of zinc ions on SDS conforms to the Langmuir adsorption isotherm and the adsorption is a chemical adsorption process.

  8. Complexation between Sodium Poly(styrenesulfonate) and Alkyltrimethylammonium Bromides in the Presence of Dodecyl Maltoside.

    Science.gov (United States)

    Fegyver, Edit; Mészáros, Róbert

    2015-04-23

    In the present paper, the impact of dodecyl maltoside (C12G2) on the association of sodium poly(styrenesulfonate) (PSS) with dodecyl- and hexadecyltrimethylammonium bromides (DTAB and CTAB) was studied. A low amount of nonionic surfactant enhances the binding of the investigated cationic amphiphiles on PSS, reducing the cationic surfactant-to-polyanion ratio needed for charge neutralization and precipitation. This effect is more pronounced for DTAB than for CTAB due to the considerably higher free surfactant concentration of the former cationic amphiphile. The synergistic surfactant binding also affects the nonequilibrium features of PSS/CTAB association via enhancing the kinetically stable concentration range of overcharged polyion/surfactant nanoparticle dispersions. With increasing C12G2 concentration, however, an opposite effect of the uncharged additive dominates. Namely, the CTAB molecules are solubilized excessively into mixed surfactant micelles, which reduces the surface charge of the PSS/CTAB/C12G2 nanoparticles and thus destabilizes their dispersion. At appropriately large nonionic surfactant concentrations, the binding of CTAB is largely reduced, resulting in the redissolution of the precipitate. In contrast, neither the destabilization nor the resolubilization effects of the added dodecyl maltoside were observed for the PSS/DTAB system due to the much lower driving force of DTAB binding compared to CTAB. Our results clearly demonstrate that the alkyl chain length of the ionic amphiphile has a pronounced effect on both the equilibrium and nonequilibrium aspects of polyion/mixed surfactant complexation which might be further exploited in various next generation applications.

  9. Study of sodium dodecyl sulfate-poly(propylene oxide) methacrylate mixed micelles.

    Science.gov (United States)

    Bastiat, Guillaume; Grassl, Bruno; Khoukh, Abdel; François, Jeanne

    2004-07-01

    Sodium dodecyl sulfate (SDS)-poly(propylene oxide) methacrylate (PPOMA) (of molecular weight M(w) = 434 g x mol(-1)) mixtures have been studied using conductimetry, static light scattering, fluorescence spectroscopy, and 1H NMR. It has been shown that SDS and PPOMA form mixed micelles, and SDS and PPOMA aggregation numbers, N(ag SDS) and N(ag PPOMA), have been determined. Total aggregation numbers of the micelles (N(ag SDS) + N(ag PPOMA)) and those of SDS decrease upon increasing the weight ratio R = PPOMA/SDS. Localization of PPOMA inside the mixed micelles is considered (i) using 1H NMR to localize the methacrylate function at the hydrophobic core-water interface and (ii) by studying the SDS-PPO micellar system (whose M(w) = 400 g x mol(-1)). Both methods have indicated that the PPO chain of the macromonomer is localized at the SDS micelle surface. Models based on the theorical prediction of the critical micellar concentration of mixed micelles and structural model of swollen micelles are used to confirm the particular structure proposed for the SDS-PPOMA system, i.e., the micelle hydrophobic core is primarily composed of the C12 chains of the sodium dodecyl sulfate, the hydrophobic core-water interface is made up of the SDS polar heads as well as methacrylate functions of the PPOMA, the PPO chains of the macromonomer are adsorbed preferentially on the surface, i.e., on the polar heads of the SDS.

  10. Effect of 1-Butyl-3-methylimidazolium Halide on the Relative Stability between Sodium Dodecyl Sulfate Micelles and Sodium Dodecyl Sulfate-Poly(ethylene oxide) Nanoaggregates.

    Science.gov (United States)

    Ferreira, Gabriel M Dias; Ferreira, Guilherme M Dias; Agudelo, Álvaro J Patiño; Hespanhol da Silva, Maria C; Rezende, Jaqueline de Paula; Pires, Ana Clarissa Dos Santos; da Silva, Luis Henrique Mendes

    2015-12-24

    It is well-known that ionic liquids (ILs) alter the properties of aqueous systems containing only surfactants. However, the effect of ILs on polymer-surfactant systems is still unknown. Here, the effect of 1-butyl-3-methylimidazolium bromide (bmimBr) and chloride (bmimCl) on the micellization of sodium dodecyl sulfate (SDS) and its interaction with poly(ethylene oxide) (PEO) was evaluated using conductimetry, fluorimetry, and isothermal titration calorimetry. The ILs decreased the critical micellar concentration (cmc) of the surfactant, stabilizing the SDS micelles. A second critical concentration (c2thc) was verified at high SDS concentrations, due to the micelle size decrease. The stability of PEO/SDS aggregates was also affected by ILs, and the critical aggregation concentration (cac) of SDS increased. Integral aggregation enthalpy changed from -0.72 in water to 2.16 kJ mol(-1) in 4.00 mM bmimBr. IL anions did not affect the SDS micellization or the beginning of PEO/SDS aggregation. Nevertheless, when chloride was replaced with bromide, the amount of SDS bound to the polymer increased. At 100.0 mM IL, the PEO-SDS interaction vanished. We suggest that the effect of ILs comes from participating in the structure of the formed aggregates, interacting with the SDS monomers at the core/interface of the micelles, and promoting preferential solvation of the polymer.

  11. Use of capillary electrophoresis-sodium dodecyl sulfate to monitor disulfide scrambled forms of an Fc fusion protein during purification process.

    Science.gov (United States)

    Hapuarachchi, Suminda; Fodor, Szilan; Apostol, Izydor; Huang, Gang

    2011-07-15

    Overexpression of recombinant Fc fusion proteins in Escherichia coli frequently results in the production of inclusion bodies that are subsequently used to produce fully functional protein by an in vitro refolding process. During the refolding step, misfolded proteins such as disulfide scrambled forms can be formed, and purification steps are used to remove these product-related impurities to produce highly purified therapeutic proteins. A variety of analytical methods are commonly used to monitor protein variants throughout the purification process. Capillary electrophoresis (CE)-based techniques are gaining popularity for such applications. In this work, we used a nonreduced capillary electrophoresis-sodium dodecyl sulfate (nrCE-SDS) method for the analysis of disulfide scrambled forms in a fusion protein. Under denatured nonreduced conditions, an extra post-shoulder peak was observed at all purification steps. Detailed characterization revealed that the peak was related to the disulfide scrambled forms and was isobaric with the correctly folded product. In addition, when sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) was used during the CE-SDS peak characterization, we observed that the migration order of scrambled forms is reversed on CE-SDS versus SDS-PAGE. This illustrates the importance of establishing proper correlation of these two techniques when they are used interchangeably to guide the purification process and to characterize proteins.

  12. Effect of Anionic Surfactant on the Thermo Acoustical Properties of Sodium Dodecyl Sulphate in Polyvinyl Alcohol Solution by Ultrasonic Method

    Directory of Open Access Journals (Sweden)

    S. Ravichandran

    2011-01-01

    Full Text Available The interaction of sodium dodecyl sulphate (SDS / poly(vinyl alcohol (PVA solution was studied by ultrasonic velocity measurements. Ultrasonic velocity, density, viscosity in mixtures of sodium dodecyl sulphate in polyvinyl alcohol was measured over the entire range of composition. From the experimental data, other related thermodynamic parameters, viz., adiabatic compressibility, intermolecular free length, surface tension, relative association, relaxation time, absorption coefficient and internal pressure were calculated. Formations of rods interfere with velocity of ultrasonic waves. Hence the ultrasonic velocity decreases with concentration. These results were interpreted in terms of polymer-surfactant complex reactions.

  13. Effect of sodium dodecyl sulfate on flow and electrokinetic properties of Na-activated bentonite dispersions

    Indian Academy of Sciences (India)

    E Günıster; S İşçı; A Alemdar; N Güngör

    2004-06-01

    The present study reports the effect of anionic surfactant sodium dodecyl sulfate (SDS, C12H25 OSO3Na) upon the electrokinetic (electrophoretic mobility, zeta potential) and rheological (viscosity, yield value) properties of the Ca-bentonitic clay found in Turkey and its Na-activated form. The SDS dispersant was added in different concentrations in the range of 1 × 10-5-5 × 10-2 mol/l. The results show that the viscosity and zeta potential values of bentonite dispersion are affected by the addition of anionic surfactant. The obtained data are analysed by considering the kind of exchangeable cations. Thixotropic property effect was observed in bentonite dispersions.

  14. Sodium Dodecyl Sulfate (SDS-Loaded Nanoporous Polymer as Anti-Biofilm Surface Coating Material

    Directory of Open Access Journals (Sweden)

    Sokol Ndoni

    2013-02-01

    Full Text Available Biofilms cause extensive damage to industrial settings. Thus, it is important to improve the existing techniques and develop new strategies to prevent bacterial biofilm formation. In the present study, we have prepared nanoporous polymer films from a self-assembled 1,2-polybutadiene-b-polydimethylsiloxane (1,2-PB-b-PDMS block copolymer via chemical cross-linking of the 1,2-PB block followed by quantitative removal of the PDMS block. Sodium dodecyl sulfate (SDS was loaded into the nanoporous 1,2-PB from aqueous solution. The SDS-loaded nanoporous polymer films were shown to block bacterial attachment in short-term (3 h and significantly reduce biofilm formation in long-term (1 week by gram-negative bacterium Escherichia coli. Tuning the thickness or surface morphology of the nanoporous polymer films allowed to extent the anti-biofilm capability.

  15. Use of nanoparticles to improve the performance of sodium dodecyl sulfate flooding in a sandstone reservoir

    Science.gov (United States)

    Ahmadi, Mohammad Ali

    2016-12-01

    One of the prominent enhanced oil recovery (EOR) methods in oil reservoirs is surfactant flooding. The purpose of this research is to study the effect of nanoparticles on the surfactant adsorption. Real reservoir sandstone rock samples were implemented in adsorption tests. The ranges of the initial surfactant and nano silica concentrations were from 500 to 5000 ppm and 500 ppm to 2000 ppm, respectively. The commercial surfactant used is sodium dodecyl sulfate (SDS) as an ionic surfactant and two different types of nano silica were employed. The rate of surfactant losses extremely depends on the concentration of surfactant in the system, and it was found that the adsorption of surfactant decreased with increasing the concentration of nano silica. Also, it was found that hydrophobic nano silica is more effective than hydrophilic nanoparticles.

  16. Improving the performance of starch-based wood adhesive by using sodium dodecyl sulfate.

    Science.gov (United States)

    Li, Zhaofeng; Wang, Jian; Cheng, Li; Gu, Zhengbiao; Hong, Yan; Kowalczyk, Agnieszka

    2014-01-01

    Sodium dodecyl sulfate (SDS) was used to improve the performance of starch-based wood adhesive. The effects of SDS on shear strength, viscosity and storage stability were investigated. It was shown that, although the addition of 1.5-2% (dry starch basis) SDS resulted in a slight decrease in shear strength, the mobility and storage stability of adhesive were significantly enhanced. Possible mechanisms regarding specific action of SDS were discussed. It was proved, using blue value or differential scanning calorimetry (DSC) analysis, that the amylose-SDS complexes were formed in the adhesive. The complex formation or simple adsorption of SDS with starch molecules might hinder the aggregation of latex particles, as shown by scanning electron microscopy images, and inhibit starch retrogradation, as observed by DSC analysis. As a result, in the presence of SDS, the adhesive had higher mobility and storage stability, indicating that SDS could be used to prepare starch-based wood adhesives with high performance.

  17. Combined Quenching Mechanism of Anthracene Fluorescence by Cetylpyridinium Chloride in Sodium Dodecyl Sulfate Micelles.

    Science.gov (United States)

    Soemo, Angela R; Pemberton, Jeanne E

    2014-03-01

    The Stern-Volmer quenching constant (KSV) for quenching of anthracene fluorescence in sodium dodecyl sulfate (SDS) micelles by pyridinium chloride has been reported previously to be 520 M(-1) based on steady state fluorescence measurements. However, such measurements cannot distinguish static versus dynamic contributions to the overall quenching. In the work reported here, the quenching dynamics of anthracene in SDS micelles by cetylpyridinium chloride (CPC), an analogue of pyridinium chloride, were investigated using both steady state and time resolved fluorescence quenching. Concurrent measurement of the decrease in fluorescence intensity and lifetime of anthracene provide a quantitative evaluation of collision induced (i.e. dynamic) versus complex formation (i.e. static) quenching of the anthracene fluorophore. The results reveal that a combined quenching mechanism is operative with approximately equal constants of 249 ± 6 M(-1) and 225 ± 12 M(-1) for dynamic and static quenching, respectively.

  18. Influence of sodium dodecyl sulfate on the reaction between Nile Blue A and hydrogen peroxide

    Directory of Open Access Journals (Sweden)

    IVANA A. JANKOVIC

    1999-05-01

    Full Text Available The influence of the anionic surfactant sodium dodecyl sulfate on the rate of the reaction between the cationic form of Nile Blue A and hydrogen peroxide was investigated in the pH range from 5 to 8.5. A retardation of the oxidation of Nile Blue A with hydrogen peroxide of three orders of magnitude was observed at pH 8.5 in the presence of anionic micelles compared to the kinetic data in water. The retardation effect was less pronounced at lower pH values. These effects were explained by the electrostatic interaction of the species involved in the reaction with the negatively charged micellar surface and their effective separation in the vicinity of the micellar surface.

  19. Improved detection of amylase activity by sodium dodecyl sulfate-polyacrylamide gel electrophoresis with copolymerized starch.

    Science.gov (United States)

    Martínez, T F; Alarcón, F J; Díaz-López, M; Moyano, F J

    2000-08-01

    An improved method, based on sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) for detection of amylase activity is described. This method will allow better characterization of certain amylases than that obtained by the Davis technique. The main features of the technique are: (i) identification of amylase bands and molecular mass determination are possible in the same gel; (ii) the hydrolysis of copolymerized substrate during electrophoretic separation is prevented using very low temperatures instead of inactivating agents such as chelating agents; and (iii) the technique is applicable to reveal amylase activity in a wide range of biological samples. The method is not useful for enzymes sensitive to SDS and for high molecular mass amylases.

  20. Epidermal cell proliferation and terminal differentiation in skin organ culture after topical exposure to sodium dodecyl sulphate

    NARCIS (Netherlands)

    Sandt, J.J.M. van de; Bos, T.A.; Rutten, A.A.J.J.L.

    1995-01-01

    Epidermal cell proliferation and differentiation were investigated in vitro after exposure to the anionic surfactant sodium dodecyl sulfate (SDS). Human skin organ cultures were exposed topically to various concentrations of SDS for 22 h, after which the irritant was removed. Cell proliferation was

  1. Modification of an acetone-sodium dodecyl sulfate disruption method for cellular protein extraction from neuropathogenic Clostridium botulinum

    Science.gov (United States)

    An acetone-sodium dodecyl sulfate (SDS) disruption method was used for the extraction of cellular proteins from neurotoxigenic Clostridium botulinum. The amount of protein extracted per gram of dry weight and the protein profile as revealed by polyacrylamide gel electrophoresis (PAGE) was comparabl...

  2. A Novel Method for Detection of Glycoproteins on Sodium Dodecyl Sulphate Polyacrylamide Gel Using Radio-Iodinated Tyrosine

    DEFF Research Database (Denmark)

    Nalla, Amarnadh; Draz, Hossam M.; Dole, Anita;

    2009-01-01

    The aim of this study is to develop a novel method for detection of glycoproteins on polyacrylamide gel. In this method, radio-iodinated-tyrosine (125I-tyrosine) was conjugated to glycoprotein by schiff's base mechanism on the sodium dodecyl sulfate- polyacrylamide gel. Ovalbumin and Concanavalin...

  3. Impact of sodium dodecyl sulphate on the dissolution of poorly soluble drug into biorelevant medium from drug-surfactant discs

    DEFF Research Database (Denmark)

    Madelung, Peter; Ostergaard, Jesper; Bertelsen, Poul

    2014-01-01

    The purpose was to elucidate the mechanism of action of sodium dodecyl sulphate (SDS) on drug dissolution from discs under physiologically relevant conditions. The effect of incorporating SDS (4-30%, w/w) and drug into discs on the dissolution constant and solubility were evaluated for the poorly...

  4. Characterization of a sodium dodecyl sulphate-degrading Pseudomonas sp. strain DRY15 from Antarctic soil.

    Science.gov (United States)

    Halmi, M I E; Hussin, W S W; Aqlima, A; Syed, M A; Ruberto, L; MacCormack, W P; Shukor, M Y

    2013-11-01

    A bacterium capable of biodegrading surfactant sodium dodecyl sulphate (SDS) was isolated from Antarctic soil. The isolate was tentatively identified as Pseudomonas sp. strain DRY15 based on carbon utilization profiles using Biolog GN plates and partial 16S rDNA molecular phylogeny. Growth characteristic studies showed that the bacterium grew optimally at 10 degrees C, 7.25 pH, 1 g l(-1) SDS as a sole carbon source and 2 g l(-1) ammonium sulphate as nitrogen source. Growth was completely inhibited at 5 g l(-1) SDS. At a tolerable initial concentration of 2 g l(-1), approximately 90% of SDS was degraded after an incubation period of eight days. The best growth kinetic model to fit experimental data was the Haldane model of substrate inhibition with a correlation coefficient value of 0.97. The maximum growth rate was 0.372 hr(-1) while the saturation constant or half velocity constant (Ks) and inhibition constant (Ki), were 0.094% and 11.212 % SDS, respectively. Other detergent tested as carbon sources at 1 g l(-1) was Tergitol NP9, Tergitol 15S9, Witconol 2301 (methyl oleate), sodium dodecylbenzene sulfonate (SDBS), benzethonium chloride, and benzalkonium chloride showed Tergitol NP9, Tergitol 15S9, Witconol 2301 and the anionic SDBS supported growth with the highest growth exhibited by SDBS.

  5. Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE of urinary protein in acute kidney injury

    Directory of Open Access Journals (Sweden)

    Sufi M Suhail

    2011-01-01

    Full Text Available Recent experimental and clinical studies have shown the importance of urinary proteomics in acute kidney injury (AKI. We analyzed the protein in urine of patients with clinical AKI using sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE for its diagnostic value, and followed them up for 40 months to evaluate prognosis. Urine from 31 consecutive cases of AKI was analyzed with SDS-PAGE to determine the low, middle and high molecular weight proteins. Fractional excretion of sodium (FENa was estimated from serum and urine creatinine and sodium (Na. The cases were followed-up for 40 months from the end of the recruitment of study cases. Glomerular protein was higher in the hematuria group when compared with the non-hematuria group (P <0.04 and in the AKI group than in the acute on chronic renal failure (AKI-on-CRF group (P <0.002. Tubular protein was higher in the AKI-on-CRF group (P <0.003 than in the AKI group. Tubular protein correlated with FENa in groups with diabetes mellitus (DM, AKI-on-CRF, and without hematuria (P <0.03, P <0.02 and P <0.004, respectively. Pattern of protein did not differ between groups with and without DM and clinical acute tubular necrosis (ATN. At the end of 40 months follow-up, category with predominantly glomerular protein progressed to chronic renal failure (CRF or end-stage renal failure in higher proportion (P <0.05. In clinical AKI, we observed that glomerular protein dominated in cases with glomerular insult, as indicated by hematuria. Tubular protein was common in the study cases with CRF, DM and cases without hematuria. This indicates tubulo-interstitial injury for AKI in these cases. Patients with predominantly glomerular protein had an adverse outcome.

  6. Sodium dodecyl benzene sulfonate-assisted synthesis through a hydrothermal reaction

    Energy Technology Data Exchange (ETDEWEB)

    Sobhani, Azam [Department of Inorganic Chemistry, Faculty of Chemistry, University of Kashan, Kashan, P.O. Box 87317–51167, Islamic Republic of Iran (Iran, Islamic Republic of); Salavati-Niasari, Masoud, E-mail: salavati@kashanu.ac.ir [Department of Inorganic Chemistry, Faculty of Chemistry, University of Kashan, Kashan, P.O. Box 87317–51167, Islamic Republic of Iran (Iran, Islamic Republic of); Institute of Nano Science and Nano Technology, University of Kashan, Kashan, P.O. Box 87317–51167, Islamic Republic of Iran (Iran, Islamic Republic of)

    2012-08-15

    Graphical abstract: Reaction of a SeCl{sub 4} aqueous solution with a NiCl{sub 2}·6H{sub 2}O aqueous solution in presence of sodium dodecyl benzene sulfonate (SDBS) as capping agent and hydrazine (N{sub 2}H{sub 4}·H{sub 2}O) as reductant, produces nanosized nickel selenide through a hydrothermal method. The effect of temperature, reaction time and amounts of reductant on the morphology, particle sizes of NiSe nanostructures has been investigated. Highlights: ► NiSe nanostructures were synthesized by hydrothermal method. ► A novel Se source was used to synthesize NiSe. ► SDBS as capping agent plays a crucial role on the morphology of products. ► A mixture of Ni{sub 3}Se{sub 2} and NiSe was prepared in the presence of 2 ml hydrazine. ► A pure phase of NiSe was prepared in the presence of 4 or 6 ml hydrazine. -- Abstract: The effects of the anionic surfactant on the morphology, size and crystallization of NiSe precipitated from NiCl{sub 2}·6H{sub 2}O and SeCl{sub 4} in presence of hydrazine (N{sub 2}H{sub 4}·H{sub 2}O) as reductant were investigated. The products have been successfully synthesized in presence of sodium dodecyl benzene sulfonate (SDBS) as surfactant via an improved hydrothermal route. A variety of synthesis parameters, such as reaction time and temperature, capping agent and amount of reducing agent have a significant effect on the particle size, phase purity and morphology of the obtained products. The sample size became bigger with decreasing reaction temperature and increasing reaction time. In the presence of 2 ml hydrazine, the samples were found to be the mixture of Ni{sub 3}Se{sub 2} and NiSe. With increasing the reaction time and amount of hydrazine a pure phase of hexagonal NiSe was obtained. X-ray diffraction analysis (XRD), scanning electron microscope (SEM) and transmission electron microscopy (TEM) images indicate phase, particle size and morphology of the products. Chemical composition and purity of the products were

  7. A new insight on the dynamics of sodium dodecyl sulfate aqueous micellar solutions by dielectric spectroscopy.

    Science.gov (United States)

    Lanzi, Leandro; Carlà, Marcello; Lanzi, Leonardo; Gambi, Cecilia M C

    2009-02-01

    Aqueous sodium dodecyl sulfate micellar solutions were investigated by a recently developed double-differential dielectric spectroscopy technique in the frequency range 100 MHz-3 GHz at 22 degrees C, in the surfactant concentration range 29.8-524 mM, explored for the first time above 104 mM. The micellar contribution to dielectric spectra was analyzed according to three models containing, respectively, a single Debye relaxation, a Cole-Cole relaxation and a double Debye relaxation. The single Debye model is not accurate enough. Both Cole-Cole and double Debye models fit well the experimental dielectric spectra. With the double Debye model, two characteristic relaxation times were identified: the slower one, in the range 400-900 ps, is due to the motion of counterions bound to the micellar surface (lateral motion); the faster one, in the range 100-130 ps, is due to interfacial bound water. Time constants and amplitudes of both processes are in fair agreement with Grosse's theoretical model, except at the largest concentration values, where interactions between micelles increase. For each sample, the volume fraction of bulk water and the effect of bound water as well as the conductivity in the low frequency limit were computed. The bound water increases as the surfactant concentration increases, in quantitative agreement with the micellar properties. The number of water molecules per surfactant molecule was also computed. The conductivity values are in agreement with Kallay's model over the whole surfactant concentration range.

  8. Thermodynamic selectivity of functional agents on zeolite for sodium dodecyl sulfate sequestration.

    Science.gov (United States)

    Leng, Ling; Wang, Jian; Qiu, Xianxiu; Zhao, Yanxiang; Yip, Yuk-Wang; Law, Ga-Lai; Shih, Kaimin; Zhou, Zhengyuan; Lee, Po-Heng

    2016-11-15

    This study proposes a thermodynamic approach to effectively select functional agents onto zeolite for sodium dodecyl sulfate (SDS) sequestration in greywater reuse. We combine isothermal titration calorimetry (ITC) and quantum chemistry simulation (QCS) to identify the interactions between SDS and agents at the molecular level. Three potential agents, cetyl trimethyl ammonium bromide (CTAB), N,N,N-trimethyltetradecan-1-aminium bromide (C14TAB), and 14-hydroxy-N,N,N-trimethyltetradecan-1-aminium bromide (C14HTAB), differ in carbon chain length and hydrophilic groups. The ITC titration of SDS with CTAB released the highest heat, followed by those with C14TAB and C14HTAB, as was the same trend for the amounts of SDS adsorbed by the respective functionalized-zeolites. Results suggest that the favorable SDS sorption occurred at the bilayer CTAB-zeolite is driven by enthalpy as similar as the SDS…CTAB interaction found, regardless of the contribution from electrostatic and/or hydrophobic behaviors, while the declined sorption is entropy-driven via the predominant hydrophobic interaction onto the monolayer CTAB-zeolite. The data presented here interpret the nature of molecularly thermodynamic quantities and enable the manipulation of sorption capacity optimization.

  9. Examination of surface adsorption of cetyltrimethylammonium bromide and sodium dodecyl sulfate.

    Science.gov (United States)

    Nakahara, Hiromichi; Shibata, Osamu; Moroi, Yoshikiyo

    2011-07-28

    Several pieces of experimental evidence of condensation of soluble surfactant molecules, cetyltrimethylammonium bromide (CTAB) and sodium dodecyl sulfate (SDS), into the air/water surface region from the bulk solution are presented at different added salt concentrations in order to substantiate that the concentrated molecules do not locate just at the air/solution interface. The insoluble monolayer just at the air/subphase interface for the two surfactants could be studied by surface pressure (π) versus molecular surface area (A), surface potential (ΔV) versus the area (A), infrared absorption of the surface region, and BAM (Brewster angle microscope) image. From surface tension versus concentration curves for the two surfactant solutions, the apparent molecular surface area and the cmc values were determined at different added salt concentrations, and the degree of counterion binding to micelle was found to be 0.70 and 0.73 for CTAB and SDS, respectively. Further examination was made on infrared absorption from the surface region of the surfactant solutions and on BAM images of the surface planes in order to examine the difference between the insoluble monolayer and the condensation in the surface region. Finally, the new concept of bilayer or bilamellar aggregate for soluble surfactant solutions is presented together with the former experimental evidence, which is consistent with several interfacial phenomena of the surfactant solutions.

  10. Effect of Addition of Sodium Dodecyl Sulfite on Physical Properties of Wheat Gluten Films

    Institute of Scientific and Technical Information of China (English)

    ZENG Yuwei; ZHAO Mouming; WANG Jinshui

    2005-01-01

    Films were made from the wheat glutens treated with 5%,10%,15%,20%,25% and 30%(wt% of gluten) of sodium dodecyl sulfite (SDS) in order to improve the properties of the films. Glycerol was used as a plasticizer.An addition of SDS in wheat glutens prior to forming films significantly increased the elongation at break(E) (P<0.05) and reduced notably the water vapor permeability(WVP) (P<0.05). In contrast,a decrease in the tensile strength(TS) of the films from gluten containing-SDS was found.Moreover,a significant decrease in PO2 and PCO2 of films from gluten treated with SDS was noticed. Although SDS-treated gluten film was slightly more yellow and darker than control one, it was not visually detrimental. It is indicated that the treatment with SDS prior to forming films greatly enhances the mechanical properties of wheat gluten films.The obivous improvement in water vapor permeability and extensibility of gluten films means that the use of SDS is a potential choice for improving properties of gluten films. The edible film was used to preserve tomatoes. The experimental results show that the shelf life of tomatoes coated with the edible film is extended, and the nutritional quality is kept well.

  11. An investigation of chitosan and sodium dodecyl sulfate interactions in acetic media

    Directory of Open Access Journals (Sweden)

    Petrović Lidija B.

    2016-01-01

    Full Text Available Polymer/surfactant association is a cooperative phenomenon where surfactant binds to the polymer in the form of aggregates, usually through electrostatic or hydrophobic forces. As already known, polyelectrolytes may interact with oppositely charged surfactants through electrostatic attraction that results in polymer/surfactant complex formation. This behavior could be desirable in wide range of application of polymer/surfactant mixtures, such as improving colloid stability, gelling, emulsification and microencapsulation. In the present study surface tension, turbidity, viscosity and electrophoretic mobility measurements were used to investigate interactions of cationic polyelectrolyte chitosan (Ch and oppositely charged anionic surfactant, sodium dodecyl sulfate (SDS, in buffered water. Obtained results show the presence of interactions that lead to Ch/SDS complexes formation at all investigated pH and for all investigated polymer concentrations. Mechanisms of interaction, as well as characteristics of formed Ch/SDS complexes, are highly dependent on their mass ratio in the mixtures, while pH has no significant influence. [Projekat Ministarstva nauke Republike Srbije, br. II46010

  12. Plasmid-mediated biodegradation of the anionic surfactant sodium dodecyl sulphate, by Pseudomonas aeruginosa S7.

    Science.gov (United States)

    Yeldho, Deepthi; Rebello, Sharrel; Jisha, M S

    2011-01-01

    Sodium dodecyl sulphate (SDS), an anionic surfactant, has been used extensively due to its low cost and excellent foaming properties. Fifteen different bacterial isolates capable of degrading SDS were isolated from detergent contaminated soil by enrichment culture technique and the degradation efficiency was assessed by Methylene Blue Active Substances (MBAS) assay. The most efficient SDS degrading isolate was selected and identified as Pseudomonas aeruginosa S7. The selected isolate was found to harbor a single 6-kb plasmid. Acridine orange, ethidium bromide, SDS and elevated temperatures of incubation failed to cure the plasmid. The cured derivatives of SDS degrading Pseudomonas aeruginosa were obtained only when ethidium bromide and elevated temperature (40 °C) were used together. Transformation of E. coli DH5α with plasmid isolated from S7 resulted in subsequent growth of the transformants on minimal salt media with SDS (0.1%) as the sole source of carbon. The SDS degradation ability of S7 and the transformant was found to be similar as assessed by Methylene Blue Active Substance Assay. The antibiotic resistance profiles of S7, competent DH5α and transformant were analyzed and it was noted that the transfer of antibiotic resistance correlated with the transfer of plasmid as well as SDS degrading property.

  13. Microenvironment of tryptophan residues in beta-lactoglobulin derivative polypeptide-sodium dodecyl sulfate complexes.

    Science.gov (United States)

    Imamura, T; Konishi, K

    1992-06-01

    The changes of microenvironment of tryptophan residues in beta-lactoglobulin A and its cyanogen bromide (CNBr) fragments with the binding of sodium dodecyl sulfate (SDS) were studied with measurements of the rates of N-bromosuccinimide (NBS) modification reactions by stopped-flow photometry. Two tryptophan residues of carboxyamidomethylated (RCM) beta-lactoglobulin A in the states of their complexes with SDS were clearly distinguishable by their differences in NBS modification rates. We confirmed by experiments with CNBr fragments containing trytophan residue. The modification rates of Trp 19 in RCM beta-lactoglobulin A-SDS complexes were about 10-fold smaller than those expected for tryptophan residues exposed entirely to the aqueous solvent. The Trp 61 was hardly changed. The change of rate constants for Trp 19 was virtually consistent with those observed when N-acetyl-L-trytophan ethylester was dissolved in SDS micelles. For various species of polypeptide-SDS complexes, all tryptophan residues were reactive to NBS and also, for some of them, the differences in NBS modification rates were observed between tryptophan residues on a common polypeptide chain. These results suggest micellar and heterogeneous bindings of SDS to polypeptides.

  14. Electrochemistry of Cytochrome P450 BM3 in Sodium Dodecyl Sulfate Films

    Science.gov (United States)

    Udit, Andrew K.; Hill, Michael G.; Gray, Harry B.

    2008-01-01

    Direct electrochemistry of the cytochrome P450 BM3 heme domain (BM3) was achieved by confining the protein within sodium dodecyl sulfate (SDS) films on the surface of basal-plane graphite (BPG) electrodes. Cyclic voltammetry revealed the heme FeIII/II redox couple at −330 mV (vs. Ag/AgCl, pH 7.4). Up to 10 V/s, the peak current was linear with scan rate, allowing us to treat the system as surface-confined within this regime. The standard heterogeneous rate constant determined at 10 V/s was estimated to be 10 s−1. Voltammograms obtained for the BM3-SDS-BPG system in the presence of dioxygen exhibited catalytic waves at the onset of FeIII reduction. The altered heme reduction potential of the BM3-SDS-graphite system indicates that SDS is likely bound in the enzyme active-site region. Compared to other P450-surfactant systems, we find redox potentials and electron transfer rates that differ by ~ 100 mV and > 10-fold, respectively, indicating that the nature of the surfactant environment has a significant effect on the observed heme redox properties. PMID:17129070

  15. Biodegradation of anionic surfactant, sodium dodecyl sulphate by Pseudomonas aeruginosa MTCC 10311.

    Science.gov (United States)

    Ambily, P S; Jisha, M S

    2012-07-01

    The anionic surfactant sodium dodecyl sulphate (SDS), the core components of detergent and cosmetic product formulations, contributes significantly to the pollution profile of sewage and wastewater of all kinds. In this study, 44 SDS degrading strains were isolated by soil enrichment methods and the utilization efficiency was assessed by methylene blue active substances (MBAS) assay and High performance liquid chromatography (HPLC) method. Isolate S2 which showed maximum degradation was identified as Pseudomonas aeruginosa MTCC 10311 based on phenotypic features and 16 S rDNA typing. The isolate was found to harbor plasmid within the size range of 9-10 kb. The cured derivative of SDS degrading Pseudomonas aeruginosa was obtained at a frequency of 10.7% by incubation with ethidium bromide (500 mg ml(-1) at 40 degrees C. 96% of SDS degradation occurred at 1500 ppm level within 48 hr of incubation, whereas higher concentration of SDS (10000 ppm) showed only 20% degradation. The optimum temperature and pH was 30 degrees C and 7.5, respectively. The additional supplementation of carbon and nitrogen source increased the degradation capacity from 93 to 95% and 90 to 96% respectively within 36 hrs of incubation.

  16. Inhibition of human hemoglobin autoxidation by sodium n-dodecyl sulphate.

    Science.gov (United States)

    Reza, Dayer Mohammad; Akbar, Moosavi-Movahedi Ali; Parviz, Norouzi; Ghourchian; Hedayat-Olah; Shahrokh, Safarian

    2002-07-31

    The effect of sodium n-dodecyl sulphate (SDS) on hemoglobin autoxidation was studied in the presence of a 100 mM phosphate buffer (pH 7.0) by different methods. These included spectrophotometry, fluorescence technique, cyclic voltametry, differential scanning calorimetry, and densitometry. Spectroscopic studies showed that SDS concentrations up to 1 mM increased deoxy-, decreases oxy-, and had no significant effect on the met- conformation of hemoglobin. Therefore, a SDS concentration up to 1 mM increased the deoxy form of hemoglobin as the folded, compact state and decreases the oxy conformation. The turbidity measurements and differential scanning calorimetry techniques indicated a more stable conformation for hemoglobin in the presence of SDS up to 1 mM. Electrochemical studies also confirmed a more difficult oxidation under these conditions. The induction of the deoxy form in the presence of SDS was confirmed by densitometry techniques. The compact structure of deoxyhemoglobin blocks the formation of met-conformation in low SDS concentrations.

  17. Interaction of poly(N-isopropylacrylamide) with sodium dodecyl sulfate below the critical aggregation concentration.

    Science.gov (United States)

    Uehara, Nobuo; Ogawa, Minami

    2014-06-10

    Interaction between the thermoresponsive polymer poly(N-isopropylacrylamide) (P-NIP) and sodium dodecyl sulfate (SDS) both above and below its phase transition temperature was examined under dilute conditions. Above the lower critical solution temperature (LCST) of P-NIP (32 °C), 0.01 wt % P-NIP specifically interacted with 1.0 × 10(-5) mol/L SDS to form a precipitate. However, when SDS was added at concentrations above or below 1.0 × 10(-5) mol/L, the P-NIP solution remained clear above the LCST. A fluorometric probe, N-phenyl-naphthalene, indicated that the hydrophobicity of the aggregates composed of P-NIP and SDS changed at an SDS concentration of 1.0 × 10(-5) mol/L. Although the hydrophobicity of the precipitate was similar to that of P-NIP alone at less than 1.0 × 10(-5) mol/L, it approached that of SDS homomicelles as the SDS concentration increased above 1.0 × 10(-5) mol/L. Dynamic light scattering and turbidimetry studies showed no P-NIP phase transition above an SDS concentration of 1.0 × 10(-5) mol/L, which is much lower than the reported critical association concentration (CAC) of SDS with P-NIP. This indicates that P-NIP interacted with SDS above the LSCT at much lower SDS concentration than the reported CAC.

  18. Toxicity Biosensor for Sodium Dodecyl Sulfate Using Immobilized Green Fluorescent Protein Expressing Escherichia coli

    Directory of Open Access Journals (Sweden)

    Lia Ooi

    2015-01-01

    Full Text Available Green fluorescent protein (GFP is suitable as a toxicity sensor due to its ability to work alone without cofactors or substrates. Its reaction with toxicants can be determined with fluorometric approaches. GFP mutant gene (C48S/S147C/Q204C/S65T/Q80R is used because it has higher sensitivity compared to others GFP variants. A novel sodium dodecyl sulfate (SDS toxicity detection biosensor was built by immobilizing GFP expressing Escherichia coli in k-Carrageenan matrix. Cytotoxicity effect took place in the toxicity biosensor which leads to the decrease in the fluorescence intensity. The fabricated E. coli GFP toxicity biosensor has a wide dynamic range of 4–100 ppm, with LOD of 1.7 ppm. Besides, it possesses short response time (0.98, and long-term stability (46 days. E. coli GFP toxicity biosensor has been applied to detect toxicity induced by SDS in tap water, river water, and drinking water. High recovery levels of SDS indicated the applicability of E. coli GFP toxicity biosensor in real water samples toxicity evaluation.

  19. Nature of large aggregates in supercooled aqueous solutions of sodium dodecyl sulfate

    Energy Technology Data Exchange (ETDEWEB)

    Franses, E.I. (Purdue Univ., West Lafayette, IN); Davis, H.T.; Miller, W.G.; Scriven, L.E.

    1980-09-18

    Preparations of 2.0 and 5.5 wt % sodium dodecyl sulfate (SDS) in 3.5 wt % (0.6 M) aqueous NaCl are equilibrium micellar solutions above 28/sup 0/C, the Krafft point of the surfactant at this salinity. These systems can be supercooled and remain transparent for hours and days. At 25/sup 0/C at equilibrium they are biphasic, a hydrated crystal phase and an aqueous salt solution phase containing only 0.01/sub 2/ wt % SDS. Conductimetry and /sup 13/C NMR show that these transparent supercooled systems are indeed supersaturated solutions and not microdispersions of the hydrated crystal. The time lag for the onset of nucleation of the crystals depends strongly on stirring details and probably on presence of gas-liquid interface. The big nonequilibrium aggregates present in the supersaturated systems resemble micelles in conductivity and molecular motion, and are likely to be metastable micelles as is presumed by Mazer, Benedek, and Carey. 21 references, 6 figures, 1 table.

  20. Solvation dynamics of DCM in a polypeptide-surfactant aggregate: gelatin-sodium dodecyl sulfate.

    Science.gov (United States)

    Halder, Arnab; Sen, Pratik; Burman, Anupam Das; Bhattacharyya, Kankan

    2004-02-03

    Solvation dynamics of 4-(dicyanomethylidene)-2-[p-(dimethylamino)styryl]-6-methyl-4H-pyran (DCM) is studied in a polypeptide-surfactant aggregate consisting of gelatin and sodium dodecyl sulfate (SDS) in potassium dihydrogen phosphate (KP) buffer. The average solvation time (tauS) in gelatin-SDS aggregate at 45 degrees C is found to be 1780 ps, which is about 13 times slower than that in 15 mM SDS in KP buffer at the same temperature. The fluorescence anisotropy decay in gelatin-SDS aggregate is also different from that in SDS micelles in KP buffer. DCM displays negligible emission in the presence of gelatin in aqueous solution. Thus the solvation dynamics in the presence of gelatin and SDS is exclusively due to the probe (DCM) molecules at the gelatin-micelle interface. The slow solvation dynamics is ascribed to the restrictions imposed on the water molecules trapped between the polypeptide chain and micellar aggregates. The critical association concentration (cac) of SDS for gelatin is determined to be 0.5 +/- 0.1 mM.

  1. Atomistic Simulation of Solubilization of Polycyclic Aromatic Hydrocarbons in a Sodium Dodecyl Sulfate Micelle.

    Science.gov (United States)

    Liang, Xujun; Marchi, Massimo; Guo, Chuling; Dang, Zhi; Abel, Stéphane

    2016-04-19

    Solubilization of two polycyclic aromatic hydrocarbons (PAHs), naphthalene (NAP, 2-benzene-ring PAH) and pyrene (PYR, 4-benzene-ring PAH), into a sodium dodecyl sulfate (SDS) micelle was studied through all-atom molecular dynamics (MD) simulations. We find that NAP as well as PYR could move between the micelle shell and core regions, contributing to their distribution in both regions of the micelle at any PAH concentration. Moreover, both NAP and PYR prefer to stay in the micelle shell region, which may arise from the greater volume of the micelle shell, the formation of hydrogen bonds between NAP and water, and the larger molecular volume of PYR. The PAHs are able to form occasional clusters (from dimer to octamer) inside the micelle during the simulation time depending on the PAH concentration in the solubilization systems. Furthermore, the micelle properties (i.e., size, shape, micelle internal structure, alkyl chain conformation and orientation, and micelle internal dynamics) are found to be nearly unaffected by the solubilized PAHs, which is irrespective of the properties and concentrations of PAHs.

  2. Application and Mechanism of Anionic Collector Sodium Dodecyl Sulfate (SDS in Phosphate Beneficiation

    Directory of Open Access Journals (Sweden)

    Kun Sun

    2017-02-01

    Full Text Available Phosphate ore is a valuable strategic resource. Most phosphate ore in China is collophane. Utilization of mid-low grade collophane is necessary to maintain social sustainable development. The gravity-flotation combination separation process can be utilized to separate mid-low grade collophane, but the process consumes a large quantity of acid in the reverse stage. Sodium dodecyl sulfate (SDS was used as a dolomite collector in this study to reduce the acid consumption of collophane flotation. SDS effectively removed dolomite from the gravity concentrate when no other reagents were present. Flotation test results showed that, compared to the conventional gravity-flotation process, the proposed SDS-based process reduced phosphoric acid dosage from 6.1 kg/t to 3.9 kg/t with similar separation results. The SDS action mechanisms on dolomite were further investigated by zeta potential analysis, single mineral flotation tests, infrared spectrum detection, and theoretical analysis. The results indicate that the SDS adsorption on dolomite is mainly physical adsorption, and that favorable separation effects between collophane and dolomite may be attributed to physical adsorption and entrainment. In addition, it also indicates that the physical adsorption can be utilized to remove dolomite from phosphate on account of zeta potential differences when the separate feed is coarse.

  3. Thermodynamic selectivity of functional agents on zeolite for sodium dodecyl sulfate sequestration

    Energy Technology Data Exchange (ETDEWEB)

    Leng, Ling; Wang, Jian [Department of Civil and Environmental Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong SAR (China); Qiu, Xianxiu; Zhao, Yanxiang; Yip, Yuk-Wang; Law, Ga-Lai [Department of Applied Biology and Chemical Technology, State Key Laboratory of Chirosciences, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong SAR (China); Shih, Kaimin; Zhou, Zhengyuan [Department of Civil Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong, Hong Kong SAR (China); Lee, Po-Heng, E-mail: poheng76@gmail.com [Department of Civil and Environmental Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong SAR (China)

    2016-11-15

    Highlights: • A thermodynamic approach to select a functional agent for adsorbent is proposed. • ITC and QCS were used to interpret the interaction between adsorbate and agent. • The interaction identifies the adsorption mechanism and performance. • This approach enables the manipulation of adsorption capacity optimization. - Abstract: This study proposes a thermodynamic approach to effectively select functional agents onto zeolite for sodium dodecyl sulfate (SDS) sequestration in greywater reuse. We combine isothermal titration calorimetry (ITC) and quantum chemistry simulation (QCS) to identify the interactions between SDS and agents at the molecular level. Three potential agents, cetyl trimethyl ammonium bromide (CTAB), N,N,N-trimethyltetradecan-1-aminium bromide (C{sub 14}TAB), and 14-hydroxy-N,N,N-trimethyltetradecan-1-aminium bromide (C{sub 14}HTAB), differ in carbon chain length and hydrophilic groups. The ITC titration of SDS with CTAB released the highest heat, followed by those with C{sub 14}TAB and C{sub 14}HTAB, as was the same trend for the amounts of SDS adsorbed by the respective functionalized-zeolites. Results suggest that the favorable SDS sorption occurred at the bilayer CTAB-zeolite is driven by enthalpy as similar as the SDS…CTAB interaction found, regardless of the contribution from electrostatic and/or hydrophobic behaviors, while the declined sorption is entropy-driven via the predominant hydrophobic interaction onto the monolayer CTAB-zeolite. The data presented here interpret the nature of molecularly thermodynamic quantities and enable the manipulation of sorption capacity optimization.

  4. Micelles in mixtures of sodium dodecyl sulfate and a bolaform surfactant.

    Science.gov (United States)

    Muzzalupo, Rita; Gente, Giacomo; La Mesa, Camillo; Caponetti, Eugenio; Chillura-Martino, Delia; Pedone, Lucia; Saladino, Maria Luisa

    2006-07-04

    Mixtures composed of water, sodium dodecyl sulfate (SDS), and a bolaform surfactant with two aza-crown ethers as polar headgroups (termed Bola C-16) were investigated by modulating the mole ratios between the components. The two surfactants have ionic and nonionic, but ionizable, headgroups, respectively. The ionization is due to the complexation of alkali ions by the aza-crown ether unit(s). Structural, thermodynamic, and transport properties of the above mixtures were investigated. Results from surface tension, translational self-diffusion, and small angle neutron scattering (SANS) are reported and discussed. Interactions between the two surfactants to form mixed micelles result in a combination of electrostatic and hydrophobic contributions. These effects are reflected in the size and shape of the aggregates as well as in transport properties. The translational diffusion of the components in mixed micelles, in particular, depends on the Bola C-16/SDS mole ratio. Nonideality of mixing of the two components was inferred from the dependence of the critical micelle concentration, cmc, on the mole fraction of Bola C-16. This behavior is also reflected in surface adsorption and in the area per polar headgroup at the air-water interface. SANS data analysis for the pure components gives results in good agreement with previous findings. An analysis of data relative to mixed systems allows us to compute some structural parameters of the mixed aggregates. The dependence of aggregation numbers, nu(T), on the Bola C-16/SDS mole ratio displays a maximum that depends on the overall surfactant content and is rationalized in terms of the nonideality of mixing. Aggregates grow perpendicularly to the major rotation axis, as formerly observed in the Bola C-16 system, and become progressively ellipsoidal in shape.

  5. Isolation of a strain of Pseudomonas putida capable of metabolizing anionic detergent sodium dodecyl sulfate (SDS

    Directory of Open Access Journals (Sweden)

    A Kumar

    2011-05-01

    Full Text Available Background and objectives: Sodium Dodecyl Sulfate (SDS is one of the most widely used anionic detergents. The present study deals with isolation and identification of SDS-degrading bacteria from a detergent contaminated pond situated in Varanasi city, India."nMaterials and Methods: Employing enrichment technique in minimal medium (PBM, SDS-degrading bacteria were isolated from pond water sample. Rate of degradation of SDS was studied in liquid PBM and also degradation of different concentrations of SDS was also studied to find out maximum concentration of SDS degraded by the potent isolates. Alkyl sulfatase activity (key enzyme in SDS degradation was estimated in crude cell extracts and multiplicity of alkyl sulfatase was studied by Native PAGE Zymography. The potent isolate was identified by 16S rRNA sequence analysis."nResults: Using enrichment technique in minimal medium containing SDS as a sole carbon source, initially three SDS degrading isolates were recovered. However, only one isolate, SP3, was found to be an efficient degrader of SDS. It was observed that this strain could completely metabolize 0.1% SDS in 16 h, 0.2% SDS in 20 h and 0.3% SDS in 24 h of incubation. Specific activity of alkyl sulfatase was 0.087±0.004 μmol SDS/mg protein/min and Native PAGE Zymography showed presence of alkyl sulfatase of Rf value of 0.21. This isolate was identified as Pseudomonas putida strain SP3."nConclusion: This is the report of isolation of SDS-degrading strain of P. putida, which shows high rate of SDS degradation and can degrade up to 0.3% SDS. It appears that this isolate can be exploited for bioremediation of this detergent from water systems.

  6. Cadmium Immobilization in Soil using Sodium Dodecyl Sulfate Stabilized Magnetite Nanoparticles

    Directory of Open Access Journals (Sweden)

    Ahmad Farrokhian Firouzi

    2017-06-01

    Full Text Available Introduction Some methods of contaminated soils remediation reduces the mobile fraction of trace elements, which could contaminate groundwater or be taken up by soil organisms. Cadmium (Cd as a heavy metal has received much attention in the past few decades due to its potential toxic impact on soil organism activity and compositions. Cadmium is a soil pollutant of no known essential biological functions, and may pose threats to soil-dwelling organisms and human health. Soil contamination with Cd usually originates from mining and smelting activities, atmospheric deposition from metallurgical industries, incineration of plastics and batteries, land application of sewage sludge, and burning of fossil fuels. Heavy metal immobilization using amendments is a simple and rapid method for the reduction of heavy metal pollution. One way of the assessment of contaminated soils is sequential extraction procedure. Sequential extraction of heavy metals in soils is an appropriate way to determine soil metal forms including soluble, exchangeable, carbonate, oxides of iron and manganese, and the residual. Its results are valuable in prediction of bioavailability, leaching rate and elements transformation in contaminated agricultural soils. Materials and Methods The objective of this study was to synthesize magnetite nanoparticles (Fe3O4 stabilized with sodium dodecyl sulfate (SDS and to investigate the effect of its different percentages (0, 1, 2.5, 5, and 10% on the different fractions of cadmium in soil by sequential extraction method. The nanoparticles were synthesized following the protocol described by Si et al. (19. The investigations were carried out with a loamy sand topsoil. Before use, the soil was air-dried, homogenized and sieved (

  7. Fabrication and study of properties of magnetite nanoparticles in hybrid micelles of polystyrene-block-polyethylene oxide and sodium dodecyl sulfate

    Energy Technology Data Exchange (ETDEWEB)

    Loginova, T. P., E-mail: tlg@ineos.ac.ru; Timofeeva, G. I.; Lependina, O. L.; Shandintsev, V. A. [Russian Academy of Sciences, Nesmeyanov Institute of Organoelement Compounds (Russian Federation); Matyushin, A. A. [Ministry of Public Health of the Russian Federation, First Moscow State Medical University (Russian Federation); Khotina, I. A. [Russian Academy of Sciences, Nesmeyanov Institute of Organoelement Compounds (Russian Federation); Shtykova, E. V. [Russian Academy of Sciences, Shubnikov Institute of Crystallography (Russian Federation)

    2016-01-15

    Magnetite nanoparticles have been formed for the first time in hybrid micelles of polystyrene-block-polyethylene oxide and sodium dodecyl sulfate in water by ultrasonic treatment at room temperature. An analysis by small-angle X-ray scattering and transmission electron microscopy (TEM) showed that magnetite nanoparticles in hybrid micelles of block copolymer and sodium dodecyl sulfate are polydesperse (have sizes from 0.5 to 20 nm). The specific magnetization of solid samples has been measured.

  8. Surface modification to produce hydrophobic nano-silica particles using sodium dodecyl sulfate as a modifier

    Energy Technology Data Exchange (ETDEWEB)

    Qiao, Bing; Liang, Yong; Wang, Ting-Jie, E-mail: wangtj@tsinghua.edu.cn; Jiang, Yanping

    2016-02-28

    Graphical abstract: Nano silica particle was modified to produce hydrophobic surface with contact angle of 107° using the water soluble SDS as a modifier through a new route. The grafted density reached 1.82–2 nm. Brønsted acid sites supply proton to react with SDS via generating carbocation, forming a Si–O–C structure. - Highlights: • Silica was modified to produce hydrophobic surface using SDS as modifier. • The route is free of organic solvent and gets perfect contact of SDS and silica. • Contact angle of modified silica particles reached 107°. • Grafted density on the silica surface reached 1.82 SDS nm{sup −2}. • Brønsted acid sites supply proton to react with SDS via generating carbocation. - Abstract: Hydrophobic silica particles were prepared using the surfactant sodium dodecyl sulfate (SDS) as a modifier by a new route comprising three processes, namely, aqueous mixing, spray drying and thermal treatment. Since SDS dissolves in water, this route is free of an organic solvent and gave a perfect dispersion of SDS, that is, there was excellent contact between SDS and silica particles in the modification reaction. The hydrophobicity of the modified surface was verified by the contact angle of the nano-sized silica particles, which was 107°. The SDS grafting density reached 1.82 nm{sup −2}, which is near the highest value in the literature. The optimal parameters of the SDS/SiO{sub 2} ratio in the aqueous phase, process temperature and time of thermal treatment were determined to be 20%, 200 °C and 30 min, respectively. The grafting mechanism was studied by comparing the modification with that on same sized TiO{sub 2} particles, which indicated that the protons of the Brønsted acid sites on the surface of SiO{sub 2} reacted with SDS to give a carbocation which then formed a Si–O–C structure. This work showed that the hydrophilic surface of silica can be modified to be a hydrophobic surface by using a water soluble modifier SDS in a

  9. Optimal concentrations of N-decanoyl-N-methylglucamine and sodium dodecyl sulfate allow the extraction and analysis of membrane proteins.

    Science.gov (United States)

    Chuang, Jen-Hua; Kao, Yu-Jing; Ruderman, Neil B; Tung, Li-Chu; Lin, Yenshou

    2011-11-15

    We studied the extraction and analysis of integral membrane proteins possessing hydrophobic and hydrophilic domains and found that a nonionic detergent called MEGA-10, used in lysis buffers, had a superior extraction effect compared to most conventional detergents. A sodium dodecyl sulfate (SDS) concentration of >0.4% (w/v) in the sample buffer was crucial for those proteins to be clearly analyzed by electrophoresis and Western blotting. Furthermore, MEGA-10 had the tendency to maximally extract proteins around its critical micelle concentration (CMC) of 0.24% (w/v). These solutions can greatly assist functional investigations of membrane proteins in the proteomics era.

  10. Thermodynamic solution properties of pefloxacin mesylate and its interactions with organized assemblies of anionic surfactant, sodium dodecyl sulphate

    Energy Technology Data Exchange (ETDEWEB)

    Usman, Muhammad [Department of Chemistry, Government College University, Faisalabad 38000 (Pakistan); Department of Chemistry, Quaid-i-Azam University, Islamabad 45320 (Pakistan); Rashid, Muhammad Abid [Department of Chemistry and Biochemistry, University of Agriculture, Faisalabad (Pakistan); Mansha, Asim [Department of Chemistry, Government College University, Faisalabad 38000 (Pakistan); Siddiq, Mohammad, E-mail: m_sidiq12@yahoo.com [Department of Chemistry, Quaid-i-Azam University, Islamabad 45320 (Pakistan)

    2013-12-10

    Graphical abstract: - Highlights: • Free energy of adsorption is more negative than free energy of micellization. • Micellization becomes more spontaneous at high temperature. • There is strong interaction between PFM and SDS. - Abstract: This manuscript reports the physicochemical behavior of antibiotic amphiphilic drug pefloxacin mesylate (PFM) and its interaction with anionic surfactant, sodium dodecyl sulfate (SDS). The data of surface tension and electrical conductivity are helpful to detect the CMC as well as to calculate surface parameters, i.e. surface pressure, π, surface excess concentration, Γ, area per molecule of drug and standard Gibbs free energy of adsorption, ΔG{sub ads} and thermodynamic parameters like standard free energy of micellization, ΔG{sub m}, standard enthalpy of micellization, ΔH{sub m} and standard entropy of micellization, ΔS{sub m}. The interaction of this drug with anionic surfactant, sodium dodecyl sulfate (SDS) was studied by electrical conductivity and UV/visible spectroscopy. This enabled us to compute the values of partition coefficient (K{sub x}), free energy of partition, ΔG{sub p}, binding constant, K{sub b}, free energy of binding, ΔG{sub b}, number of drug molecules per micelle, n, and thermodynamic parameters of drug–surfactant interaction.

  11. Quantitation of antihistamines in pharmaceutical preparations by liquid chromatography with a micellar mobile phase of sodium dodecyl sulfate and pentanol.

    Science.gov (United States)

    Gil-Agustí, M; Monferrer-Pons, L; Esteve-Romero, J; García-Alvarez-Coque, M C

    2001-01-01

    A reversed-phase liquid chromatographic procedure with a micellar mobile phase of sodium dodecyl sulfate (SDS), containing a small amount of pentanol, was developed for the control of 7 antihistamines of diverse action in pharmaceutical preparations (tablets, capsules, powders, solutions, and syrups): azatadine, carbinoxamine, cyclizine, cyproheptadine, diphenhydramine, doxylamine, and tripelennamine. The retention times of the drugs were <9 min with a mobile phase of 0.15M SDS-6% (v/v) pentanol. The recoveries with respect to the declared compositions were in the range of 93-110%, and the intra- and interday repeatabilities and interday reproducibility were <1.2%. The results were similar to those obtained with a conventional 60 + 40 (v/v) methanol-water mixture, with the advantage of reduced toxicity, flammability, environmental impact, and cost of the micellar-pentanol solutions. The lower risk of evaporation of the organic solvent dissolved in the micellar solutions also increased the stability of the mobile phase.

  12. Investigation on Molecular Non-covalent Interaction in the Sodium Dodecyl Benzene Sulfonatepolychrome Blue B-protein Replacement Reaction

    Institute of Scientific and Technical Information of China (English)

    GAO,Hong-Wen(郜洪文); WU,Ji-Rong(邬继荣); SHEN,Rong(沈荣)

    2004-01-01

    The molecular non-covalent interaction often originates from the electrostatic attraction and accords with the Langmuir isothermal adsorption. The sodium dodecyl benzene sulfonate (SDBS)-polychrome blue B (PCB)-protein [bovine serum albumin (BSA), ovalbumin (OVA) and myoglobin (MB)] ternary reaction has been investigated at Ph 3.88. Protein to replace PCB from the PCB-SDBS binding product was used to characterize the assembly of an invisible-spectral compound, SDBS, on proteins by measuring the variation of PCB light-absorption by the microsurface adsorption-spectral correction (MSASC) technique. The effect of ionic strength and temperature on the aggregation was studied. Results showed that the aggregates SDBS92·BSA, SDBS58·OVA and SDBS15·MB at 30 ℃ and SDBS83·BSA, SDBS39·OVA and SDBS10·MB at 50 ℃ are formed.

  13. Micelle enhanced and native spectrofluorimetric methods for determination of sertindole using sodium dodecyl sulfate as sensitizing agent.

    Science.gov (United States)

    El-Kosasy, Amira M; Hussein, Lobna A; Sedki, Nehal G; Salama, Nahla N

    2016-01-15

    Two stability indicating spectrofluorimetric methods were developed and validated for the determination of sertindole (SER) in the presence of its acid and oxidative degradates at λ(ex) 257 nm and λ(em) 335 nm. Method A was based on measuring the native fluorescence of SER using isopropanol as solvent. Method B was based on the enhancement of native fluorescence of SER quenched in aqueous media by using micellar microenvironment created by sodium dodecyl sulfate (SDS) anionic micelles using Britton Robinson Buffer (BRB) pH3.29 as solvent. Different factors affecting fluorescence intensity; both native and enhanced, were carefully studied to reach the optimum conditions of measurements. The proposed spectrofluorimetric methods were validated in accordance with ICH guidelines and were successfully applied for the determination of SER in bulk powder and pharmaceutical preparation with high sensitivity and stability indicating power. They were also statistically compared to the manufacturer methods with no significant difference in performance.

  14. A comparative study of sodium dodecyl sulfate and freezing/thawing treatment on wheat starch: The role of water absorption.

    Science.gov (United States)

    Tao, Han; Wang, Pei; Zhang, Bao; Wu, Fengfeng; Jin, Zhengyu; Xu, Xueming

    2016-06-05

    The effect of freezing on functionality of native and sodium dodecyl sulfate (SDS)-treated wheat starches was investigated, with the aim of understanding the role of water absorption during freezing process. SDS is one of most efficient detergents to remove non-starch components (such as proteins and lipids) for starches but does not cause any apparent damage on granular structure. Slow swelling could be converted to rapid swelling by SDS washing, indicating higher water absorption. Freezing process induced slight roughness on starch granules but the non-starch components content was little affected. Combined SDS+freezing treatment significantly decreased both amylose and proteins non-starch components contents, which was accompanied with high gelatinization temperatures, melting enthalpy, and pasting viscosities. A smaller bread specific volume was obtained from SDS+freezing-treated starches while the crumb firmness significantly increased (pstarch granules, leading to high water absorption and making granules sensitive to the freezing treatment.

  15. Quantitation of yeast total proteins in sodium dodecyl sulfate-polyacrylamide gel electrophoresis sample buffer for uniform loading.

    Science.gov (United States)

    Sheen, Hyukho

    2016-04-01

    Proteins in sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) sample buffer are difficult to quantitate due to SDS and reducing agents being in the buffer. Although acetone precipitation has long been used to clean up proteins from detergents and salts, previous studies showed that protein recovery from acetone precipitation varies from 50 to 100% depending on the samples tested. Here, this article shows that acetone precipitates proteins highly efficiently from SDS-PAGE sample buffer and that quantitative recovery is achieved in 5 min at room temperature. Moreover, precipitated proteins are resolubilized with urea/guanidine, rather than with SDS. Thus, the resolubilized samples are readily quantifiable with Bradford reagent without using SDS-compatible assays.

  16. Occurrence of photoluminescence and onion like structures decorating graphene oxide with europium using sodium dodecyl sulfate surfactant

    Science.gov (United States)

    Cedeño, V. J.; Rangel, R.; Cervantes, J. L.; Lara, J.; Alvarado, J. J.; Galván, D. H.

    2017-07-01

    Graphene oxide decoration with europium was carried out using SDS (sodium dodecyl sulfate) as the surfactant. The reaction was performed in a microwave oven and subsequently underwent thermal treatment under hydrogen flow. The results found in the present work demonstrate that through the use of SDS surfactant aggregates of hemi-cylindrical and onion-like structures could be obtained; which propitiate an enhanced synergistic photoluminescence located at the red wavelength. On the other hand, after thermal treatment the aggregates disappear providing a good dispersion of europium, however a decrease in the photoluminescence signal is observed. The graphene oxide decorated with europium was characterized by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), Fourier infrared transform spectroscopy (FTIR), RAMAN spectroscopy, x-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM) techniques, showing the characteristic features of graphene oxide and europium.

  17. Measuring the enthalpies of interaction between glycine, L-cysteine, glycylglycine, and sodium dodecyl sulfate in aqueous solutions

    Science.gov (United States)

    Badelin, V. G.; Mezhevoi, I. N.; Tyunina, E. Yu.

    2017-03-01

    Calorimetric measurements of enthalpies of solution Δsol H m for glycine, L-cysteine, and glycylglycine in aqueous solutions of sodium dodecyl sulfate (SDS) with concentrations of up to 0.05 mol kg-1 are made. Standard enthalpy of solution Δsol H 0 and enthalpy of transfer Δtr H 0 of the dipeptide from water into mixed solvent are calculated. The calculated enthalpy coefficients of paired interactions of amino acids and dipeptide with SDS prove to be positive. Hydrophobic interactions between the biomolecules and SDS are found to have a major impact on the enthalpies of interaction in the three-component systems under study, within the indicated range of concentrations.

  18. Differential refractometric determination of binding of sodium dodecyl sulfate to protein using high-performance gel chromatography.

    Science.gov (United States)

    Rao, P F; Takagi, T

    1988-10-01

    When sodium dodecyl sulfate (SDS) is added to a high-performance gel chromatographic column equilibrated with a buffer solution containing SDS at a level above the critical micelle concentration, the surplus SDS migrates as micelles giving a sharp peak. The presence of an unfolded protein in the sample solution gives a polypeptide peak in advance of the SDS micelle peak. As the result of SDS binding to the polypeptide, the SDS micelle peak is attenuated in comparison to that in the absence of protein. Thus the amount of SDS bound to the polypeptide can be determined accurately and simply from the decrease in the area of the SDS micelle peak. This approach is particularly useful for precise determination of bound SDS, which is pertinent to understanding the state of the protein polypeptide-SDS complex under the conditions of SDS-polyacrylamide gel electrophoresis.

  19. Contribution of sodium dodecyl sulphate and sodium lauric acid in the one-pot synthesis of intercalated ZnAl-layered double hydroxides

    Indian Academy of Sciences (India)

    Fengzhu Lv; Zilin Meng; Penggang Li; Yihe Zhang; Guocheng Lv; Qian Zhang; Zhilei Zhang

    2015-08-01

    Anion surfactants, sodium dodecyl sulphate (SDS) and sodium lauric acid (SLA), with almost the same chain length but different anion groups were used together as intercalates to prepare intercalated ZnAl–layered double hydroxides (ZnAl–LDHs). Their composition, structure and morphology were characterized by Fourier transform infrared, X-ray fluorescence, thermogravimetric and X-ray diffraction (XRD). The results indicated SDS intended to maintain the lamellae structure of LDHs, but SLA was more likely to expand the basal spacings of LDHs in the present system. The arrangement of the surfactants in the interlayer of ZnAl–LDHs was also simulated by Materials Studio. The basal spacings of the LDHs calculated based on simulated structure consisted with that from XRD.

  20. Preparative isolation of a cytotoxic principle of a forest mushroom Suillus luteus by sodium dodecyl sulfate based "salting-in" countercurrent chromatography.

    Science.gov (United States)

    Yang, Zhi; Hu, Xueqian; Wu, Shihua

    2016-02-01

    In the course of screening new anticancer natural products, an edible forest mushroom Suillus luteus (L. Ex Franch). Gray was found to have potent cytotoxicity against several human cancer cells. However, the lipophilic sample made some countercurrent chromatography solvent systems emulsify, which caused difficulties in the separation of its cytotoxic components. Here, we found that the addition of an organic salt sodium dodecyl sulfate could efficiently shorten the settling time of the mushroom sample solutions by eliminating the emulsification of two-phase solvent systems. Moreover, we found that sodium dodecyl sulfate could play a new "salting-in" role and made the partition coefficients of the solutes decrease with the increased concentrations. Thus, a sodium dodecyl sulfate based salting-in countercurrent chromatography method has been successfully established for the first time for preparative isolation of a cytotoxic principle of the mushroom. The active component was identified as isosuillin. Whole results indicated that sodium dodecyl sulfate could be used as an efficient salting-in reagent for two-phase solvent system selection and targeted countercurrent chromatography isolation. It is very useful for current natural products isolation and drug discovery.

  1. SODIUM DI-N-DODECYL PHOSPHATE VESICLES IN AQUEOUS-SOLUTION - EFFECTS OF ETHANOL, PROPANOL, AND TETRAHYDROFURAN ON THE GEL TO LIQUID-PHASE TRANSITION

    NARCIS (Netherlands)

    BLANDAMER, MJ; BRIGGS, B; BUTT, MD; WATERS, M; CULLIS, PM; ENGBERTS, JBFN; HOEKSTRA, D; MOHANTY, RK

    1994-01-01

    For aqueous solutions containing vesicles formed by sodium di-n-dodecyl phosphate, the gel to liquid-crystal transition occurs near 35 degrees C, the temperature T-m. When ethanol is added, T-m decreases, but the scan shows evidence of several transitions as more alcohol is added. The effect of adde

  2. A molecular simulation probing of structure and interaction for supramolecular sodium dodecyl sulfate/single-wall carbon nanotube assemblies.

    Science.gov (United States)

    Xu, Zhijun; Yang, Xiaoning; Yang, Zhen

    2010-03-10

    Here we report a larger-scale atomic-level molecular dynamics (MD) simulation for the self-assembly of sodium dodecyl sulfate (SDS) surfactant on single-walled carbon nanotube (SWNT) surfaces and the interaction between supramolecular SDS/SWNT aggregates. We make an effort to address several important problems in regard to carbon nanotube dispersion/separation. At first, the simulation provides comprehensive direct evidence for SDS self-assembly structures on carbon nanotube surfaces, which can help to clarify the relevant debate over the exact adsorption structure. We also, for the first time, simulated the potential of mean force (PMF) between two SWNTs embedded in SDS surfactant micelles. A novel unified PMF approach has been applied to reveal various cooperative interactions between the SDS/SWNT aggregates, which is different from the previous electrostatic repulsion explanation. The unique role of sodium ions revealed here provides a new microscopic understanding of the recent experiments in the electrolyte tuning of the interfacial forces on the selective fractionation of SDS surrounding SWNTs.

  3. Enzymatic hydrolysis of sodium dodecyl sulphate (SDS)-pretreated newspaper for cellulosic ethanol production by Saccharomyces cerevisiae and Pichia stipitis.

    Science.gov (United States)

    Xin, Fengxue; Geng, Anli; Chen, Ming Li; Gum, Ming Jun Marcus

    2010-10-01

    Fermentation of enzymatic hydrolysate of waste newspaper was investigated for cellulosic ethanol production in this study. Various nonionic and ionic surfactants were applied for waste newspaper pretreatment to increase the enzymatic digestibility. The surfactant-pretreated newspaper was enzymatically digested in 0.05 M sodium citrate buffer (pH 4.8) with varying solid content, filter paper unit loading (FPU/g newspaper), and ratio of filter paper unit/beta-glucosidase unit (FPU/CBU). Newspaper pretreated with the anionic surfactant sodium dodecyl sulphate (SDS) demonstrated the highest sugar yield. The addition of Tween-80 in the enzymatic hydrolysis process enhanced the enzymatic digestibility of newspaper pretreated with all of the surfactants. Enzymatic hydrolysis of SDS-pretreated newspaper with 15% solid content, 15 FPU/g newspaper, and FPU/CBU of 1:4 resulted in a newspaper hydrolysate conditioning 29.07 g/L glucose and 4.08 g/L xylose after 72 h of incubation at 50 degrees C. The fermentation of the enzymatic hydrolysate with Saccharomyces cerevisiae, Pichia stipitis, and their co-culture produced 14.29, 13.45, and 14.03 g/L of ethanol, respectively. Their corresponding ethanol yields were 0.43, 0.41, and 0.42 g/g.

  4. Absorption, fluorescence, and acid-base equilibria of rhodamines in micellar media of sodium dodecyl sulfate

    Science.gov (United States)

    Obukhova, Elena N.; Mchedlov-Petrossyan, Nikolay O.; Vodolazkaya, Natalya A.; Patsenker, Leonid D.; Doroshenko, Andrey O.; Marynin, Andriy I.; Krasovitskii, Boris M.

    2017-01-01

    Rhodamine dyes are widely used as molecular probes in different fields of science. The aim of this paper was to ascertain to what extent the structural peculiarities of the compounds influence their absorption, emission, and acid-base properties under unified conditions. The acid-base dissociation (HR+ ⇄ R + H+) of a series of rhodamine dyes was studied in sodium n-dodecylsulfate micellar solutions. In this media, the form R exists as a zwitterion R±. The indices of apparent ionization constants of fifteen rhodamine cations HR+ with different substituents in the xanthene moiety vary within the range of pKaapp = 5.04 to 5.53. The distinct dependence of emission of rhodamines bound to micelles on pH of bulk water opens the possibility of using them as fluorescent interfacial acid-base indicators.

  5. Effect of Sodium Sulfite, Sodium Dodecyl Sulfate, and Urea on the Molecular Interactions and Properties of Whey Protein Isolate-Based Films

    Science.gov (United States)

    Schmid, Markus; Prinz, Tobias K.; Stäbler, Andreas; Sängerlaub, Sven

    2017-01-01

    Whey protein coatings and cast films are promising for use as food packaging materials. Ongoing research is endeavoring to reduce their permeability. The intention of this study was to evaluate the effect of the reactive additives sodium sulfite, sodium dodecyl sulfate (SDS), and urea on the oxygen barrier, water vapor barrier, and protein solubility of whey protein cast films. The concentration of the reactive additives was 1 to 20 wt.-%. Dried whey protein cast films were used as substrate materials. The water vapor transmission rate, the oxygen permeability, and the protein solubility were measured. Effective diffusion coefficients and effective sorption coefficients were calculated from the results of the water vapor sorption experiments. The presence of sodium sulfite resulted in an increased number of hydrophobic interactions and hydrogen bonds and a slightly decreased number of disulfide bonds. The oxygen permeability decreased from 68 to 46 cm3 (STP/standard temperature and pressure) 100 μm (m2 d bar)−1 for 1 wt.-% SDS in the whey protein cast film. The water vapor transmission rate decreased from 165 to 44 g 100 μm (m2 d)−1 measured at 50 to 0% r. h. for 20 wt.-% SDS in the whey protein cast film. The reduction in the water vapor transmission rate correlated with the lower effective diffusion coefficient. PMID:28149835

  6. Effect of sodium sulfite, sodium dodecyl sulfate, and urea on the molecular interactions and properties of whey protein isolate-based films

    Science.gov (United States)

    Schmid, Markus; Prinz, Tobias K.; Stäbler, Andreas; Sängerlaub, Sven

    2016-12-01

    Whey protein coatings and cast films are promising for use as food packaging materials. Ongoing research is endeavoring to reduce their permeability. The intention of this study was to evaluate the effect of the reactive additives sodium sulfite, sodium dodecyl sulfate (SDS), and urea on the oxygen barrier, water vapor barrier, and protein solubility of whey protein cast films. The concentration of the reactive additives was 1 to 20 wt.-%. Dried whey protein cast films were used as substrate materials. The water vapor transmission rate, the oxygen permeability, and the protein solubility were measured. Effective diffusion coefficients and effective sorption coefficients were calculated from the results of the water vapor sorption experiments. The presence of sodium sulfite resulted in an increased number of hydrophobic interactions and hydrogen bonds and a slightly decreased number of disulfide bonds. The oxygen permeability decreased from 68 to 46 cm³ (STP / standard temperature and pressure) 100 µm (m² d bar)-1 for 1 wt.-% SDS in the whey protein cast film. The water vapor transmission rate decreased from 165 to 44 g 100 µm (m² d)-1 measured at 50 to 0 % r. h. for 20 wt.-% SDS in the whey protein cast film. The reduction in the water vapor transmission rate correlated with the lower effective diffusion coefficient.

  7. Effect of A Long Chain Carboxylate Acid on Sodium Dodecyl Sulfate Micelle Structure: A SANS Study

    Science.gov (United States)

    Patriati, Arum; Giri Rachman Putra, Edy; Seok Seong, Baek

    2010-01-01

    The effect of a different hydrocarbon chain length of carboxylate acid, i.e. dodecanoic acid, CH3(CH)10COOH or lauric acid and hexadecanoic acid, CH3(CH2)14COOH or palmitic acid as a co-surfactant in the 0.3 M sodium dedecyl sulfate, SDS micellar solution has been studied using small angle neutron scattering (SANS). The present of lauric acid has induced the SDS structural micelles. The ellipsoid micelles structures changed significantly in length (major axis) from 22.6 Å to 37.1 Å at a fixed minor axis of 16.7 Å in the present of 0.005 M to 0.1 M lauric acid. Nevertheless, this effect did not occur in the present of palmitic acid with the same concentration range. The present of palmitic acid molecules performed insignificant effect on the SDS micelles growth where the major axis of the micelle was elongated from 22.9 Å to 25.3 Å only. It showed that the appropriate hydrocarbon chain length between surfactant and co-surfactant molecules emerged as one of the determining factors in forming a mixed micelles structure.

  8. A conductometric investigation of hydroxypropylmethyl cellulose/sodium dodecyl sulfate/nonionic surfactant systems

    Directory of Open Access Journals (Sweden)

    Petrović Lidija B.

    2014-01-01

    Full Text Available Surfactant mixtures are very often used in various cosmetic and pharmaceutical products because they commonly act in synergism and provide more favorable properties than the single surfactants. At the same time, the 9 presence of polymers in mixtures of surfactants may lead to molecular interactions thereby affecting product stability and activity. For these reasons it is very important to determine the surfactant interactions influence on 1micellization and mixed micellization, as well as polymer-surfactants mixed micelles interactions. In this work we examined self-aggregation of nonionic surfactants, polysorbate 20 (Tween 20, polyoxyethylene octylphenyl ether (Triton X100 and polyoxyethylene-polyoxypropylene block copolymer (Pluronic F68 with ionic surfactant, sodium dodecylsulfate, in aqueous solution at 40ºC using conductometric titration method. It was found that concentration region for mixed micelle formation depends on nonionic surfactant characteristics and its concentration. Formation of surfactants mixed micelles in the presence of nonionic polymer, hydroxypropylmethyl cellulose, and their binding to polymer hydrophobic sites, were investigated too. Analysis of obtained results points to different kinds of interactions in investigated systems, which are crucial for their application. [Projekat Ministarstva nauke Republike Srbije, br. III 46010

  9. Highly selective colorimetric detection of Ni2+ using silver nanoparticles cofunctionalized with adenosine monophosphate and sodium dodecyl sulfonate

    Science.gov (United States)

    Feng, Jiayu; Jin, Weiwei; Huang, Pengcheng; Wu, Fangying

    2017-09-01

    We report a dual-ligand strategy based on silver nanoparticles (AgNPs) for highly selective detection of Ni2+ using colorimetric techniques. Adenosine monophosphate (AMP) and sodium dodecyl sulfonate (SDS) were both used as ligands to modify AgNPs. The presence of Ni2+ induces the aggregation of AgNPs through cooperative electrostatic interaction and metal-ligand interaction, resulting in a color change from bright yellow to orange. The cofunctionalized AgNPs showed obvious advantages over the ones functionalized only by AMP or SDS in terms of selectivity. Under the optimized conditions, this sensing platform for Ni2+ works in the concentration range of 4.0 to 60 μM and has a low detection limit of 0.60 μM. In addition, the colorimetric assay is very fast, and the whole analysis can be completed within a few minutes. Thus, it can be directly used in tap water and lake water samples. [Figure not available: see fulltext.

  10. Thermodynamics of sodium dodecyl sulphate-salicylic acid based micellar systems and their potential use in fruits postharvest.

    Science.gov (United States)

    Cid, A; Morales, J; Mejuto, J C; Briz-Cid, N; Rial-Otero, R; Simal-Gándara, J

    2014-05-15

    Micellar systems have excellent food applications due to their capability to solubilise a large range of hydrophilic and hydrophobic substances. In this work, the mixed micelle formation between the ionic surfactant sodium dodecyl sulphate (SDS) and the phenolic acid salicylic acid have been studied at several temperatures in aqueous solution. The critical micelle concentration and the micellization degree were determined by conductometric techniques and the experimental data used to calculate several useful thermodynamic parameters, like standard free energy, enthalpy and entropy of micelle formation. Salicylic acid helps the micellization of SDS, both by increasing the additive concentration at a constant temperature and by increasing temperature at a constant concentration of additive. The formation of micelles of SDS in the presence of salicylic acid was a thermodynamically spontaneous process, and is also entropically controlled. Salicylic acid plays the role of a stabilizer, and gives a pathway to control the three-dimensional water matrix structure. The driving force of the micellization process is provided by the hydrophobic interactions. The isostructural temperature was found to be 307.5 K for the mixed micellar system. This article explores the use of SDS-salicylic acid based micellar systems for their potential use in fruits postharvest.

  11. Structural Studies on Nonequilibrium Microstructures of Dioctyl Sodium Dodecyl Sulfosuccinate (Aerosol-OT in p-Toluenesulfonic Acid and Phosphatidylcholine

    Directory of Open Access Journals (Sweden)

    M. K. Temgire

    2012-01-01

    Full Text Available Several microstructures are evolved at the interface when sparingly soluble solid surfactants come in contact with water. One class of these microstructures is termed as “myelin figures”; these were observed when phosphatidylcholine came in contact with water. Although the myelins are initially simple rod-like, complex forms like helices, coils and so forth. appear in the later stage. Finally, the myelins fuse together to form a complex mosaic-like structure. When studied by taking a cross-section using cryoscanning electron microscopy, it revealed concentric circular pattern inside the myelin figures. The cross-sections of (dioctyl sodium dodecyl sulfosiccinate AOT/water system myelin internal structures were lost. When p-toluenesulfonic acid (PTS 2 wt% was present in the water phase, AOT myelins revealed the internal microstructures. It has annular concentric ring-like structure with a core axon at the centre. Further investigation revealed new microstructures for the first time having multiple axons in the single-myelin strand.

  12. A small-angle neutron scattering study of sodium dodecyl sulfate-poly(propylene oxide) methacrylate mixed micelles.

    Science.gov (United States)

    Bastiat, Guillaume; Grassl, Bruno; Borisov, Oleg; Lapp, Alain; François, Jeanne

    2006-03-15

    Mixed micelle of protonated or deuterated sodium dodecyl sulfate (SDS and SDSd25, respectively) and poly(propylene oxide) methacrylate (PPOMA) are studied by small-angle neutron scattering (SANS). In all the cases the scattering curves exhibit a peak whose position changes with the composition of the system. The main parameters which characterize mixed micelles, i.e., aggregation numbers of SDS and PPOMA, geometrical dimensions of the micelles and degree of ionisation are evaluated from the analysis of the SANS curves. The position q(max) of the correlation peak can be related to the average aggregation numbers of SDS-PPOMA and SDSd25-PPOMA mixed micelles. It is found that the aggregation number of SDS decreases upon increasing the weight ratio PPOMA/SDS (or SDSd25). The isotopic combination, which uses the "contrast effect" between the two micellar systems, has allowed us to determine the mixed micelle composition. Finally, the SANS curves were adjusted using the RMSA for the structure factor S(q) of charged spherical particles and the form factor P(q) of spherical core-shell particle. This analysis confirms the particular core-shell structure of the SDS-PPOMA mixed micelle, i.e., a SDS "core" micelle surrounded by the shell formed by PPOMA macromonomers. The structural parameters of mixed micelles obtained from the analysis of the SANS data are in good agreement with those determined previously by conductimetry and fluorescence studies.

  13. Hexavalent Molybdenum Reduction to Mo-Blue by a Sodium-Dodecyl-Sulfate-Degrading Klebsiella oxytoca Strain DRY14

    Directory of Open Access Journals (Sweden)

    M. I. E. Halmi

    2013-01-01

    Full Text Available Bacteria with the ability to tolerate, remove, and/or degrade several xenobiotics simultaneously are urgently needed for remediation of polluted sites. A previously isolated bacterium with sodium dodecyl sulfate- (SDS- degrading capacity was found to be able to reduce molybdenum to the nontoxic molybdenum blue. The optimal pH, carbon source, molybdate concentration, and temperature supporting molybdate reduction were pH 7.0, glucose at 1.5% (w/v, between 25 and 30 mM, and 25°C, respectively. The optimum phosphate concentration for molybdate reduction was 5 mM. The Mo-blue produced exhibits an absorption spectrum with a maximum peak at 865 nm and a shoulder at 700 nm. None of the respiratory inhibitors tested showed any inhibition to the molybdenum-reducing activity suggesting that the electron transport system of this bacterium is not the site of molybdenum reduction. Chromium, cadmium, silver, copper, mercury, and lead caused approximately 77, 65, 77, 89, 80, and 80% inhibition of the molybdenum-reducing activity, respectively. Ferrous and stannous ions markedly increased the activity of molybdenum-reducing activity in this bacterium. The maximum tolerable concentration of SDS as a cocontaminant was 3 g/L. The characteristics of this bacterium make it a suitable candidate for molybdenum bioremediation of sites cocontaminated with detergent pollutant.

  14. ISOLATION OF EGG DROP SYNDROME VIRUS AND ITS MOLECULAR CHARACTERIZATION USING SODIUM DODECYL SULPHATE POLYACRYLAMIDE GEL ELECTROPHORESIS

    Directory of Open Access Journals (Sweden)

    M. H. Rasool, S. U. Rahman and M. K. Mansoor

    2005-10-01

    Full Text Available Six isolates of egg drop syndrome (EDS virus were recovered from five different outbreaks of EDS in commercial laying hens in and around Faisalabad. The aberrant eggs were fed to the susceptible laying hens for experimental induction of infection. The samples from infected birds (egg washing, cloacal swabs, oviducts and spleens were collected, processed and inoculated into 11-day old duck embryos. The presence of virus in harvested allanto-amniotic fluid was monitored by spot and microhaemagglutination tests and confirmed by haemagglutination inhibition and agar gel precipitation tests. The EDS virus grew well in duck embryos and agglutinated only avian but not mammalian red blood cells. These isolates were purified through velocity density gradient centrifugation. Protein concentration was determined through Lowry method and sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE was conducted by loading 300 µg protein concentration on 12.5% gel using discontinuous buffer system. All the six isolates showed 13 polypeptides, which were identical to those described in the referral EDS-76 virus (strain-127. The molecular weights of the polypeptides ranged from 6.5 KDa to 126 KDa.

  15. Silver nanoparticles synthesis in aqueous solutions using sulfite as reducing agent and sodium dodecyl sulfate as stabilizer

    Energy Technology Data Exchange (ETDEWEB)

    Lopez-Miranda, A.; Lopez-Valdivieso, A., E-mail: alopez@uaslp.mx [Universidad Autonoma de San Luis Potosi, Instituto de Metalurgia (Mexico); Viramontes-Gamboa, G. [Universidad Michoacana de San Nicolas de Hidalgo, Facultad de Ciencia Fisico-Matematicas (Mexico)

    2012-09-15

    The synthesis of silver nanoparticles has been carried out in aqueous solutions in a stirred semibatch reactor through the reduction of silver ions (Ag{sup +}) by sulfite ions (SO{sub 3}{sup 2-}), which were added at a tightly controlled rate up to a final sulfite/silver molar ratio of 0.45. Sodium dodecyl sulfate (SDS) was used as the stabilizer at concentrations below its critical micelle concentration. The effects of temperature, sulfite addition rate, and SDS concentration have been assessed. Ag{sup +} turned to Ag{sup 0} in 5 min or less only when the synthesis was performed at 97 Degree-Sign C and not below. The sulfite addition rates studied were 0.5, 7.5, 15, and 90 {mu}mol/min. The size, shape, polydispersity, and stability of the nanoparticles were determined by the sulfite addition rate and SDS concentration. At low SDS concentration (4 mM), stable, spherical shape, small size nanoparticles were formed only at the two intermediate sulfite addition rates. At the highest sulfite addition rate, 9 nm mean size spherical nanoparticles having a low {+-}5 nm polydispersity were produced at a high SDS concentration of 10 mM. With the low SDS concentration, larger truncated and spherical shape nanoparticles were obtained. UV-Vis spectrophotometry and transmission electron microscopy were used to characterize the nanoparticles.

  16. Silver nanoparticles synthesis in aqueous solutions using sulfite as reducing agent and sodium dodecyl sulfate as stabilizer

    Science.gov (United States)

    López-Miranda, A.; López-Valdivieso, A.; Viramontes-Gamboa, G.

    2012-09-01

    The synthesis of silver nanoparticles has been carried out in aqueous solutions in a stirred semibatch reactor through the reduction of silver ions (Ag+) by sulfite ions (SO3 2-), which were added at a tightly controlled rate up to a final sulfite/silver molar ratio of 0.45. Sodium dodecyl sulfate (SDS) was used as the stabilizer at concentrations below its critical micelle concentration. The effects of temperature, sulfite addition rate, and SDS concentration have been assessed. Ag+ turned to Ag0 in 5 min or less only when the synthesis was performed at 97 °C and not below. The sulfite addition rates studied were 0.5, 7.5, 15, and 90 μmol/min. The size, shape, polydispersity, and stability of the nanoparticles were determined by the sulfite addition rate and SDS concentration. At low SDS concentration (4 mM), stable, spherical shape, small size nanoparticles were formed only at the two intermediate sulfite addition rates. At the highest sulfite addition rate, 9 nm mean size spherical nanoparticles having a low ±5 nm polydispersity were produced at a high SDS concentration of 10 mM. With the low SDS concentration, larger truncated and spherical shape nanoparticles were obtained. UV-Vis spectrophotometry and transmission electron microscopy were used to characterize the nanoparticles.

  17. Photochemistry of "end-only" oligo-p-phenylene ethynylenes: complexation with sodium dodecyl sulfate reduces solvent accessibility.

    Science.gov (United States)

    Hill, Eric H; Evans, Deborah G; Whitten, David G

    2013-08-06

    Cationic oligo-p-phenylene ethynylenes are very effective light-activated biocides and biosensors but degrade upon exposure to light. In this study, we explore the photochemistry of a class of "end-only" compounds from this series, which have cationic moieties on the ends of the backbone. Product characterization by mass spectrometry reveals that the photoreactivity of these molecules is higher than that of a previously studied oligomer and that the primary products of photolysis result from the addition of water or oxygen across the triple bond. In addition, a product suggesting the addition of peroxide or other reactive oxygen species across the triple bond was observed. To explore avenues by which the photodegradation of these compounds can be mitigated, the effects of complexation with sodium dodecyl sulfate micelles on their photochemistry was explored. Classical molecular dynamics simulations revealed that compounds that were protected from photolysis by SDS buried their phenylene ethynylene backbones into the interior of the micelle, protecting it from contact with water. This work has revealed a molecular basis for the protection of a novel class of light-activated biocides from irradiation that is consistent with the proposed photochemistry of these compounds. This information can be useful for developing photodegradation-resistant biocidal materials and applications for current compounds and leads to new molecular design.

  18. Effect of low concentration sodium dodecyl sulfate on the electromigration of palonosetron hydrochloride stereoisomers in micellar electrokinetic chromatography.

    Science.gov (United States)

    Hu, Shao-Qiang; Wang, Gui-Xia; Guo, Wen-Bo; Guo, Xu-Ming; Zhao, Min

    2014-05-16

    The effect of low concentrations of sodium dodecyl sulfate (SDS) on the separation of palonosetron hydrochloride (PALO) stereoisomers by micellar electrokinetic chromatography (MEKC) has been investigated. It was found that the addition of SDS prolongs the migration time and the migration order of four stereoisomers changes regularly with the SDS concentration. Good separations for all the four stereoisomers were achieved at appropriate SDS concentration. The effect of SDS on the electromigration (mobilities) of PALO stereoisomers has been studied, in order to explain its effect on the separation by MEKC. It was found that low concentrations of SDS added into the separation media forms negatively charged complexes with PALO stereoisomers and hence reverses their electromigration direction. Furthermore, the migration order between two enantiomeric pairs is also reversed because the enantiomeric pair with a bigger positive mobility than that of another pair turns to have a bigger negative mobility when bound with SDS. Based on these results, the effect of SDS on the MEKC separation of PALO stereoisomers was elucidated reasonably. The performance of the developed chiral MEKC method was validated by the analysis of a real sample.

  19. Cytochrome P450 102A2 Catalyzes Efficient Oxidation of Sodium Dodecyl Sulphate: A Molecular Tool for Remediation

    Directory of Open Access Journals (Sweden)

    Irene Axarli

    2010-01-01

    Full Text Available Bacterial cytochrome P450s (CYPs constitute an important family of monooxygenase enzymes that carry out essential roles in the metabolism of endogenous compounds and foreign chemicals. In the present work we report the characterization of CYP102A2 from B. subtilis with a focus on its substrate specificity. CYP102A2 is more active in oxidation of sodium dodecyl sulphate (SDS than any other characterized CYP. The effect of SDS and NADPH concentration on reaction rate showed nonhyperbolic and hyperbolic dependence, respectively. The enzyme was found to exhibit a bell-shaped curve for plots of activity versus pH, over pH values 5.9–8.5. The rate of SDS oxidation reached the maximum value approximately at pH 7.2 and the pH transition observed controlled by two pas in the acidic (pa=6.7±0.08 and basic (pa=7.3±0.06 pH range. The results are discussed in relation to the future biotechnology applications of CYPs.

  20. Sodium dodecyl sulfate/β-cyclodextrin vesicles embedded in chitosan gel for insulin delivery with pH-selective release

    Directory of Open Access Journals (Sweden)

    Zhuo Li

    2016-07-01

    Full Text Available In an answer to the challenge of enzymatic instability and low oral bioavailability of proteins/peptides, a new type of drug-delivery vesicle has been developed. The preparation, based on sodium dodecyl sulfate (SDS and β-cyclodextrin (β-CD embedded in chitosan gel, was used to successfully deliver the model drug-insulin. The self-assembled SDS/β-CD vesicles were prepared and characterized by particle size, zeta potential, appearance, microscopic morphology and entrapment efficiency. In addition, both the interaction of insulin with vesicles and the stability of insulin loaded in vesicles in the presence of pepsin were investigated. The vesicles were crosslinked into thermo-sensitive chitosan/β-glycerol phosphate solution for an in-situ gel to enhance the dilution stability. The in vitro release characteristics of insulin from gels in media at different pH values were investigated. The insulin loaded vesicles–chitosan hydrogel (IVG improved the dilution stability of the vesicles and provided pH-selective sustained release compared with insulin solution–chitosan hydrogel (ISG. In vitro, IVG exhibited slow release in acidic solution and relatively quick release in neutral solutions to provide drug efficacy. In simulated digestive fluid, IVG showed better sustained release and insulin protection properties compared with ISG. Thus IVG might improve the stability of insulin during its transport in vivo and contribute to the bioavailability and therapeutic effect of insulin.

  1. Sodium dodecyl sulfate/β-cyclodextrin vesicles embedded in chitosan gel for insulin delivery with pH-selective release.

    Science.gov (United States)

    Li, Zhuo; Li, Haiyan; Wang, Caifen; Xu, Jianghui; Singh, Vikramjeet; Chen, Dawei; Zhang, Jiwen

    2016-07-01

    In an answer to the challenge of enzymatic instability and low oral bioavailability of proteins/peptides, a new type of drug-delivery vesicle has been developed. The preparation, based on sodium dodecyl sulfate (SDS) and β-cyclodextrin (β-CD) embedded in chitosan gel, was used to successfully deliver the model drug-insulin. The self-assembled SDS/β-CD vesicles were prepared and characterized by particle size, zeta potential, appearance, microscopic morphology and entrapment efficiency. In addition, both the interaction of insulin with vesicles and the stability of insulin loaded in vesicles in the presence of pepsin were investigated. The vesicles were crosslinked into thermo-sensitive chitosan/β-glycerol phosphate solution for an in-situ gel to enhance the dilution stability. The in vitro release characteristics of insulin from gels in media at different pH values were investigated. The insulin loaded vesicles-chitosan hydrogel (IVG) improved the dilution stability of the vesicles and provided pH-selective sustained release compared with insulin solution-chitosan hydrogel (ISG). In vitro, IVG exhibited slow release in acidic solution and relatively quick release in neutral solutions to provide drug efficacy. In simulated digestive fluid, IVG showed better sustained release and insulin protection properties compared with ISG. Thus IVG might improve the stability of insulin during its transport in vivo and contribute to the bioavailability and therapeutic effect of insulin.

  2. Impact of model perfume molecules on the self-assembly of anionic surfactant sodium dodecyl 6-benzene sulfonate.

    Science.gov (United States)

    Bradbury, Robert; Penfold, Jeffrey; Thomas, Robert K; Tucker, Ian M; Petkov, Jordan T; Jones, Craig; Grillo, Isabelle

    2013-03-12

    The impact of two model perfumes with differing degrees of hydrophobicity/hydrophilicity, linalool (LL) and phenylethanol (PE), on the solution structure of anionic surfactant sodium dodecyl 6-benzene sulfonate, LAS-6, has been studied by small angle neutron scattering, SANS. For both types of perfume molecules, complex phase behavior is observed. The phase behavior depends upon the concentration, surfactant/perfume composition, and type of perfume. The more hydrophilic perfume PE promotes the formation of more highly curved structures. At relatively low surfactant concentrations, small globular micelles, L1, are formed. These become perfume droplets, L(sm), stabilized by the surfactant at much higher perfume solution compositions. At higher surfactant concentrations, the tendency of LAS-6 to form more planar structures is evident. The more hydrophobic linalool promotes the formation of more planar structures. Combined with the greater tendency of LAS-6 to form planar structures, this results in the planar structures dominating the phase behavior for the LAS-6/linalool mixtures. For the LAS-6/linalool mixture, the self-assembly is in the form of micelles only at the lowest surfactant and perfume concentrations. Over most of the concentration-composition space explored, the structures are predominantly lamellar, L(α), or vesicle, L(v), or in the form of a lamellar/micellar coexistence. At low and intermediate amounts of LL, a significantly different structure is observed, and the aggregates are in the form of small, relatively monodisperse vesicles (i.e., nanovesicles), L(sv).

  3. Sodium dodecyl sulfate-assisted hydrothermal synthesis of mesoporous nickel cobaltite nanoparticles with enhanced catalytic activity for methanol electrooxidation

    Science.gov (United States)

    Ding, Rui; Qi, Li; Jia, Mingjun; Wang, Hongyu

    2014-04-01

    Mesoporous nickel cobaltite (NiCo2O4) nanoparticles have been synthesized via a facile hydrothermal strategy with the assistance of sodium dodecyl sulfate (SDS) soft template (ST). Their physicochemical properties have been characterized via X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy-dispersive X-ray spectra (EDS), transmission electron microscopy (TEM), X-ray photoelectron spectra (XPS) and nitrogen sorption measurements. Their electrocatalytic performances have been examined by cyclic voltammetry (CV), linear sweep voltammetry (LSV), chronoamperometry (CA) and electrochemical impedance spectroscopy (EIS) tests. The obtained NiCo2O4 materials exhibit a typical nanoscale crystalline hexagonal morphology with specific surface area (SSA) and mesopore volume of 88.63 m2 g-1 and 0.298 cm3 g-1. Impressively, the SDS-assisted NiCo2O4 electrode shows a catalytic current density of 125 mA cm-2 and 72% retention for consecutive 1000 s at 0.6 V in 1 M KOH and 0.5 M CH3OH electrolytes towards methanol (CH3OH) electrooxidation, which is better than the one without SDS assistance. The pronounced electrocatalytic activity is largely ascribed to their higher surface intensities of Co and Ni species and superior mesoporous nanostructures, which provide the richer electroactive sites and faster electrochemical kinetics, leading to the enhanced electrocatalytic activity.

  4. Nonlinear response of a batch BZ oscillator to the addition of the anionic surfactant sodium dodecyl sulfate.

    Science.gov (United States)

    Sciascia, Luciana; Lombardo, Renato; Turco Liveri, Maria Liria

    2007-02-15

    The response of the Belousov-Zhabotinsy (BZ) system to the addition of increasing amounts of the anionic surfactant sodium dodecyl sulfate (SDS) was monitored at 25.0 degrees C in stirred batch conditions. The presence of SDS in the reaction mixture influences the oscillatory parameters, i.e., induction period and oscillation period, to an extent that depends on the surfactant concentration. The experimental results have shown that the induction period increases slightly on increasing surfactant concentration and, then, a further increase in the [SDS] leads to an enhancement while the oscillation period increases monotonously on increasing SDS concentration. It has been proposed that the response of the oscillatory BZ system to the addition of SDS is due to the peculiar capability of the organized surfactant assemblies to affect the reactivity by selectively sequestering some key reacting species. Indeed, explanations of the experimental results have been given on the basis of the role played by the micellar shape, which in turn dictates the hydrophobic nature. The suggested perturbation effects have been supported by performing viscosity measurements on the aqueous SDS solutions and by the spectrophotometric estimation of the binding constant of the bromine species to the micellar aggregates. This study has indirectly corroborated the existence of two kind of micelles and unambiguously revealed that the bromine species show a different affinity toward the spherical and rod-like micelles.

  5. A Microfluidic Approach to Investigating a Synergistic Effect of Tobramycin and Sodium Dodecyl Sulfate on Pseudomonas aeruginosa Biofilms.

    Science.gov (United States)

    Shin, Soojeong; Ahmed, Ishtiaq; Hwang, Jangsun; Seo, Youngmin; Lee, Eunwon; Choi, Jonghoon; Moon, Sangjun; Hong, Jong Wook

    2016-01-01

    In recent years, a microfluidic technology has contributed a significant role in biological research, specifically for the study of biofilms. Bacterial biofilms are a source of infections and contamination in the environment due to an extra polymeric matrix. Inadequate uses of antibiotics make the bacterial biofilms antibiotic resistant. Therefore, it is important to determine the effective concentration of antibiotics in order to eliminate bacterial biofilms. The present microfluidic study was carried out to analyze the activities of tobramycin and sodium dodecyl sulfate (SDS) against Pseudomonas aeruginosa biofilms with a continuous flow in order to achieve a greater delivery of the agents. The results show that a co-treatment of tobramycin and SDS significantly reduced the biomass of biofilms (by more than 99%) after 24 h. Tobramycin and SDS killed and detached bacteria in the cores of biofilms. Evidently, our data suggest that a microchannel would be effective for both quantitative and qualitative evaluations in order to test combinatorial effect of drugs and chemicals on a complexed biological system including biofilm.

  6. Sodium dodecyl sulfate-polyacrylamide gel electrophoretic method for assessing the quaternary state and comparative thermostability of avidin and streptavidin.

    Science.gov (United States)

    Bayer, E A; Ehrlich-Rogozinski, S; Wilchek, M

    1996-08-01

    Avidin, a positively charged egg-white protein, aggregates extensively when mixed at ambient temperatures with anionic detergents, such as sodium dodecyl sulfate (SDS). The resultant aggregates fail to penetrate the stacking gel during polyacrylamide gel electrophoresis (PAGE). To prevent the formation of such aggregates, avidin was acetylated and the pI was thus reduced. Acetylated avidin was found to behave in a manner similar to that of streptavidin; under nondenaturing conditions (i.e., incubation of samples at room temperature), both proteins normally migrated mainly as tetramers with a tendency to form oligomers of the tetramer. When samples were boiled, both proteins migrated mainly as the monomer. The comparative stability properties of avidin and streptavidin were also examined using SDS-PAGE by heating samples and determining the extent of dissociation of tetramers to monomers as a function of temperature. A distinctive transition temperature could be defined for individual samples. Using this assay, it was determined that, in the absence of biotin, the quaternary structure of streptavidin is more stable than that of avidin. Biotin appears to stabilize structures of both avidin and streptavidin to a similar degree. Acetylation of avidin thus provides a simple means to analyze the quaternary structure of the molecule using SDS-PAGE.

  7. Interfacial properties and fluorescence of a coagulating protein extracted from Moringa oleifera seeds and its interaction with sodium dodecyl sulphate.

    Science.gov (United States)

    Maikokera, R; Kwaambwa, H M

    2007-04-01

    The surfactant behaviour of aqueous coagulating protein extracted from Moringa oleifera seeds has been investigated by surface tension measurements. The interaction of the coagulant protein with an anionic surfactant sodium dodecyl sulphate (SDS) has been monitored by surface tension and intrinsic protein fluorescence measurements. The extracted protein shows some weak surface activity at low concentrations. To achieve maximum surface activity (i.e. maximum reduction in surface tension of water), substantially higher concentrations of protein are required. The coagulant protein-SDS interaction scheme did not exhibit the behaviour of weakly interacting polymer-surfactant systems and the SDS interacts in a monomeric form with the protein. The association process of SDS with the coagulant protein is supported by protein fluorescence measurements. SDS has an effect on the fluorescence of the coagulant protein indicating that the local environment of tryptophan in the protein changes as SDS concentration below its critical micelle concentration is increased. These results have led us to the conclusions that: (1) the protein extracted from M. oleifera seeds has significant surfactant behaviour; (2) the coagulant protein interacts strongly with SDS and the protein might have specific binding sites for SDS; (3) there is formation of protein-SDS complex.

  8. Partial characterization of biosurfactant from Lactobacillus pentosus and comparison with sodium dodecyl sulphate for the bioremediation of hydrocarbon contaminated soil.

    Science.gov (United States)

    Moldes, A B; Paradelo, R; Vecino, X; Cruz, J M; Gudiña, E; Rodrigues, L; Teixeira, J A; Domínguez, J M; Barral, M T

    2013-01-01

    The capability of a cell bound biosurfactant produced by Lactobacillus pentosus, to accelerate the bioremediation of a hydrocarbon-contaminated soil, was compared with a synthetic anionic surfactant (sodium dodecyl sulphate SDS-). The biosurfactant produced by the bacteria was analyzed by Fourier transform infrared spectroscopy (FTIR) that clearly indicates the presence of OH and NH groups, C=O stretching of carbonyl groups and NH nebding (peptide linkage), as well as CH2-CH3 and C-O stretching, with similar FTIR spectra than other biosurfactants obtained from lactic acid bacteria. After the characterization of biosurfactant by FTIR, soil contaminated with 7,000 mg Kg(-1) of octane was treated with biosurfactant from L. pentosus or SDS. Treatment of soil for 15 days with the biosurfactant produced by L. pentosus led to a 65.1% reduction in the hydrocarbon concentration, whereas SDS reduced the octane concentration to 37.2% compared with a 2.2% reduction in the soil contaminated with octane in absence of biosurfactant used as control. Besides, after 30 days of incubation soil with SDS or biosurfactant gave percentages of bioremediation around 90% in both cases. Thus, it can be concluded that biosurfactant produced by L. pentosus accelerates the bioremediation of octane-contaminated soil by improving the solubilisation of octane in the water phase of soil, achieving even better results than those reached with SDS after 15-day treatment.

  9. Small-angle neutron scattering from mixtures of sodium dodecyl sulfate and a cationic, bolaform surfactant containing azobenzene.

    Science.gov (United States)

    Hubbard, F Pierce; Santonicola, Gabriella; Kaler, Eric W; Abbott, Nicholas L

    2005-07-05

    This paper reports on the microstructures formed in aqueous solutions containing mixtures of sodium dodecyl sulfate (SDS) and a photosensitive, bolaform surfactant, bis(trimethylammoniumhexyloxy)azobenzene dibromide (BTHA). By using quasi-elastic light scattering and small-angle neutron scattering, we determined that aqueous solutions containing SDS and the trans isomer of BTHA (0.1 wt % total surfactant, 15 mol % BTHA, 85 mol % SDS) form vesicles with average hydrodynamic diameters of 1350 +/- 50 angstroms and bilayer thicknesses of 35 +/- 2 angstroms. The measured bilayer thickness is consistent with a model of the vesicle bilayer in which the trans isomer of BTHA spans the bilayer. Upon illumination with UV light, the BTHA underwent photoisomerization to produce a cis-rich photostationary state (80% cis isomer). We measured this photoisomerization to drive the reorganization of vesicles into cylindrical aggregates with cross-sectional radii of 19 +/- 3 angstroms and average hydrodynamic diameters of 240 +/- 50 angstroms. Equilibration of the cis-rich solution in the dark at 25 degrees C for 12 h or illumination of the solution with visible light leads to the recovery of the trans-rich photostationary state of the solution and the reformation of vesicles, thus demonstrating the potential utility of this system as the basis of a tunable fluid.

  10. Sodium dodecyl sulfate coated poly (vinyl) chloride: an alternative support for solid phase extraction of some transition and heavy metals.

    Science.gov (United States)

    Marahel, Farzaneh; Ghaedi, Mehrorang; Shokrollahi, Ardeshir; Montazerozohori, Morteza; Davoodi, Shahnaz

    2009-01-01

    A simple and relatively fast approach for developing a solid phase extraction has been described and used for determination of trace quantities of some heavy and transition metal ions with sodium dodecyl sulfate (SDS)-coated poly vinyl chloride (PVC) modified with bis(2-hydroxyacetophenone)-1,4-butanediimine (BHABDI) ligand. The adsorbed ions were stripped from the solid phase by 10 mL of 3M nitric acid as eluent. The eluting solution was analyzed for metals content (cadmium, chromium, cobalt, copper, lead and zinc) by flame atomic absorption spectrometry (FAAS). The main factors such as pH, amount of ligand and PVC, amount and type of surfactant, and condition of eluting solutions on the sorption recovery of metal ions have been investigated in detail. The relative standard deviation was found in the range of 1.0-3.2% for 0.2 microg mL(-1)of metals ions. After optimization of the extraction condition and the instrumental parameters, a detection limit was found to be in the range of 1.2-3.1 microg L(-1), with enrichment factor of 50 was achieved. The method was successfully applied for the determination of these metals contents in real samples with satisfactory results.

  11. Inactivation of salmonella in biofilms and on chicken cages and preharvest poultry by levulinic Acid and sodium dodecyl sulfate.

    Science.gov (United States)

    Zhao, Tong; Zhao, Ping; Cannon, Jennifer L; Doyle, Michael P

    2011-12-01

    Surface contamination (skin and feathers) of broilers with Salmonella occurs primarily during growth and transportation. Immediately after transporting chickens, chicken cage doors were sprayed with a foam containing 3% levulinic acid plus 2% sodium dodecyl sulfate (SDS). Samples were collected for Salmonella assay after 45 min. Salmonella on cage doors was reduced from 19% (19 of 100 doors) before treatment to 1% (1 of 100 doors) after treatment, coliform counts were reduced from 6 to 8 to 2 to 4 log CFU/9 cm(2), and aerobic plate counts were reduced from 7 to 9 to 4 to 6 log CFU/9 cm(2). Whole chicken carcasses with feathers were inoculated with 10(8) CFU of Salmonella Enteritidis, soaked for 5 min at 21°C in 72 liters of a treatment or control solution, and assayed for Salmonella. Salmonella counts on chickens treated with water were 6.8 to 8.5 log CFU/9 cm(2), those treated with 50 ppm of calcium hypochlorite were 7.6 to 8.9 log CFU/9 cm(2), and those treated with 3% levulinic acid plus 2% SDS were 4-log reduction). Results of biofilm studies on surfaces of various materials revealed that a 3% levulinic acid plus 2% SDS treatment used as either a foam or liquid for 10 min effectively reduced Salmonella populations by 5 and >6 log CFU/cm(2), respectively.

  12. Small angle neutron scattering study of sodium dodecyl sulfate micellar growth driven by addition of a hydrotropic salt.

    Science.gov (United States)

    Hassan, P A; Fritz, Gerhard; Kaler, Eric W

    2003-01-01

    The structures of aggregates formed in aqueous solutions of an anionic surfactant, sodium dodecyl sulfate (SDS), with the addition of a cationic hydrotropic salt, p-toluidine hydrochloride (PTHC), have been investigated by small angle neutron scattering (SANS). The SANS spectra exhibit a pronounced peak at low salt concentration, indicating the presence of repulsive intermicellar interactions. Model-independent real space information about the structure is obtained from a generalized indirect Fourier transformation (GIFT) technique in combination with a suitable model for the interparticle structure factor. The interparticle interaction is captured using the rescaled mean spherical approximation (RMSA) closure relation and a Yukawa form of the interaction potential. Further quantification of the geometrical parameters of the micelles was achieved by a complete fit of the SANS data using a prolate ellipsoidal form factor and the RMSA structure factor. The present study shows that PTHC induces a decrease in the fractional charge of the micelles due to adsorption at the micellar surface and consequent growth of the SDS micelles from nearly globular to rodlike as the concentration of PTHC increases.

  13. Partial Characterization of Biosurfactant from Lactobacillus pentosus and Comparison with Sodium Dodecyl Sulphate for the Bioremediation of Hydrocarbon Contaminated Soil

    Directory of Open Access Journals (Sweden)

    A. B. Moldes

    2013-01-01

    Full Text Available The capability of a cell bound biosurfactant produced by Lactobacillus pentosus, to accelerate the bioremediation of a hydrocarbon-contaminated soil, was compared with a synthetic anionic surfactant (sodium dodecyl sulphate SDS-. The biosurfactant produced by the bacteria was analyzed by Fourier transform infrared spectroscopy (FTIR that clearly indicates the presence of OH and NH groups, C=O stretching of carbonyl groups and NH nebding (peptide linkage, as well as CH2–CH3 and C–O stretching, with similar FTIR spectra than other biosurfactants obtained from lactic acid bacteria. After the characterization of biosurfactant by FTIR, soil contaminated with 7,000 mg Kg−1 of octane was treated with biosurfactant from L. pentosus or SDS. Treatment of soil for 15 days with the biosurfactant produced by L. pentosus led to a 65.1% reduction in the hydrocarbon concentration, whereas SDS reduced the octane concentration to 37.2% compared with a 2.2% reduction in the soil contaminated with octane in absence of biosurfactant used as control. Besides, after 30 days of incubation soil with SDS or biosurfactant gave percentages of bioremediation around 90% in both cases. Thus, it can be concluded that biosurfactant produced by L. pentosus accelerates the bioremediation of octane-contaminated soil by improving the solubilisation of octane in the water phase of soil, achieving even better results than those reached with SDS after 15-day treatment.

  14. Adsorption of hydroxamate siderophores and EDTA on goethite in the presence of the surfactant sodium dodecyl sulfate

    Directory of Open Access Journals (Sweden)

    Xu Jide

    2009-06-01

    Full Text Available Abstract Siderophore-promoted iron acquisition by microorganisms usually occurs in the presence of other organic molecules, including biosurfactants. We have investigated the influence of the anionic surfactant sodium dodecyl sulfate (SDS on the adsorption of the siderophores DFOB (cationic and DFOD (neutral and the ligand EDTA (anionic onto goethite (α-FeOOH at pH 6. We also studied the adsorption of the corresponding 1:1 Fe(III-ligand complexes, which are products of the dissolution process. Adsorption of the two free siderophores increased in a similar fashion with increasing SDS concentration, despite their difference in molecule charge. In contrast, SDS had little effect on the adsorption of EDTA. Adsorption of the Fe-DFOB and Fe-DFOD complexes also increased with increasing SDS concentrations, while adsorption of Fe-EDTA decreased. Our results suggest that hydrophobic interactions between adsorbed surfactants and siderophores are more important than electrostatic interactions. However, for strongly hydrophilic molecules, such as EDTA and its iron complex, the influence of SDS on their adsorption seems to depend on their tendency to form inner-sphere or outer-sphere surface complexes. Our results demonstrate that surfactants have a strong influence on the adsorption of siderophores to Fe oxides, which has important implications for siderophore-promoted dissolution of iron oxides and biological iron acquisition.

  15. Positional isomers of linear sodium dodecyl benzene sulfonate: solubility, self-assembly, and air/water interfacial activity.

    Science.gov (United States)

    Ma, Jian-Guo; Boyd, Ben J; Drummond, Calum J

    2006-10-10

    Commercial linear alkyl benzene sulfonates (ABS) are a very important class of anionic surfactants that are employed in a wide variety of applications, especially those involving wetting and detergency. Linear ABS surfactants generally consist of a complex mixture of different chain lengths and positional isomers. This diversity and level of complexity makes it difficult to develop fundamental structure-property correlations for the commercial surfactants. In this work, six monodisperse headgroup positional isomers of sodium para-dodecyl benzene sulfonate (Na-x-DBS, x = 1-6) have been studied. The influence of headgroup position and added electrolyte (NaCl) on the solubility and self-assembly (micellar and vesicular aggregation and lyotropic liquid crystalline phase behavior) in the temperature range from 10 to 90 degrees C have been investigated. Additionally, the air-aqueous solution interfacial adsorption at 25 (no added NaCl) and 50 degrees C (from 0 to 1.0 M added NaCl) has been examined. The observed physicochemical behavior is interpreted in terms of local molecular packing constraints, and in the case of the lyotropic liquid crystalline behavior global aggregate packing constraints as well.

  16. Effects of buffered vinegar and sodium dodecyl sulfate plus levulinic acid on Salmonella Typhimurium survival, shelf-life, and sensory characteristics of ground beef patties.

    Science.gov (United States)

    Stelzleni, Alexander M; Ponrajan, Amudhan; Harrison, Mark A

    2013-09-01

    The inclusion of two sources of buffered vinegar and sodium dodecyl sulfate plus levulinic acid were studied as interventions for Salmonella Typhimurium and for their effect on shelf-life and sensory characteristics of ground beef. For the Salmonella challenge, beef trimmings (80/20) were inoculated then treated with 2% (w/v) liquid buffered vinegar (LVIN), 2.5% (w/w) powdered buffered vinegar (PVIN), a solution containing 1.0% levulinic acid plus 0.1% sodium dodecyl sulfate (SDLA) at 10% (w/v), or had no intervention applied (CNT). The same trim source and production methods were followed during production of patties for shelf-life and sensory testing without inoculation. SDLA patties had the largest reduction (PSalmonella. However, LVIN and PVIN had the least (Pcharacteristics, except PVIN exhibited stronger off-flavor (P<0.05).

  17. Effect of NaCl on the spectral and kinetic properties of cresyl violet (CV)-sodium dodecyl sulphate (SDS) complex

    Indian Academy of Sciences (India)

    K I Priyadarsini; Hari Mohan

    2003-08-01

    Effect of added NaCl on the spectral and kinetic properties of cationically charged dye (cresyl violet) and anionically charged surfactant (sodium dodecyl sulphate) were studied in the pre-micellar and micellar regions. Addition of 0.2M NaCl to dye-surfactant solution decreased the critical micellar concentration for the micellization of the dye in sodium dodecyl sulphate to 1.2 × 10-3 M. Time-resolved studies using a stopped-flow spectrometer showed that NaCl influences the dynamics of micellisation. Addition of NaCl during the dye-surfactant complex formation converted the complex into micellized form at NaCl concentration of 0.01 to 0.05 M. In contrast, much higher concentration of NaCl (2 M) is required for the salting-out effect of the dye-surfactant complex for conversion to the micellized form.

  18. Conductometric study of sodium dodecyl sulfate - nonionic surfactant (Triton X-100, Tween 20, Tween 60, Tween 80 or Tween 85) mixed micelles in aqueous solution

    OpenAIRE

    Ćirin Dejan M; Poša Mihalj M.; Krstonošić Veljko S.; Milanović Maja Lj.

    2012-01-01

    The present study is concerned with the determination of the critical micelle concentration (cmc) of mixed micelles of sodium dodecyl sulfate with one of five nonionic surfactants (Triton X-100, Tween 20, Tween 60, Tween 80 or Tween 85) from conductance measurements. Based on the calculated values of the β parameters we have noticed that SDS-nonionic surfactants mostly showed strong synergistic effect. It was found that nonionic surfactants with mainly longer and more hydrophobic tail s...

  19. Identification of coagulase-negative staphylococci by using sodium dodecyl sulfate-polyacrylamide gel electrophoresis and rRNA restriction patterns.

    OpenAIRE

    Pennington, T. H.; Harker, C.; Thomson-Carter, F

    1991-01-01

    A total of 1,417 staphylococcal and micrococcal strains were collected from the beards and scalps of 10 subjects over a period of 8 months. Sixteen strains identified as Staphylococcus epidermidis with an API system had distinctive yellow colonies on nutrient agar plates and sodium dodecyl sulfate-polyacrylamide gel electrophoresis whole-cell polypeptide profiles similar to those of Staphylococcus capitis; this identification was confirmed by analysis of rRNA gene restriction patterns.

  20. The Catalysis of Sodium Dodecyl Sulfate/1-Pentanol/Water W/O Microemulsion on the Photoisomerization of trans-Stilbene

    Institute of Scientific and Technical Information of China (English)

    Xia GUO; Ling LIN; Rong GUO

    2004-01-01

    The photoisomerization of trans-stilbene was studied in the water in oil (W/O) micro- emulsion formed by SDS (sodium dodecyl sulfate), n-C5H11OH (1-pentanol) and H2O. The experimental results show that after 2-minute UV-irradiation, the yield of cis-stilbene is higher in W/O microemulsion than in homogeneous solvent-n-C5H11OH.

  1. Optical and Thermal Properties of Zn/Al-Layered Double Hydroxide Nanocomposite Intercalated with Sodium Dodecyl Sulfate

    Directory of Open Access Journals (Sweden)

    Samaneh Babakhani

    2014-01-01

    Full Text Available Zn/Al-LDH-SDS nanocomposites have been prepared using a coprecipitation method in different molar ratio of Zn2+/Al3+ = 2, 3, and 4 at pH = 10 and different concentrations of sodium dodecyl sulfate solution (0.2 M, 0.4 M, and 0.8 M. The XRD and FTIR data show the successful intercalation of SDS into the LDH interlayer. The XRD diffractogram showed that the basal spacing for Zn/Al–NO3- is 0.89 nm compared to 2.54–2.61 nm for the Zn/Al-SDS nanocomposite. Optical band gap of the samples was calculated using Kubelka-Munk model. Due to the presence of LDH phase, two band gap energies (Eg1 and Eg2 were observed. The values of Eg1 and Eg2 were found around 4.8 eV and 3.75 eV for Zn/Al-LDH (r = 2, 3, and 4. The values of band gap of LDH-SDS nanocomposites were found to increase to around 4.2 eV and 5.2 eV. For Zn4Al-LDH-SDS with 0.4 M and 0.8 M of SDS, only one energy gap at around 3.23 eV was observed. The optical band gap of SO42- phase increased as the amount of SDS increases. Thermal diffusivity of the resulted nanocomposite was also investigated.

  2. Antigenic profile of heat-killed versus thimerosal-treated Leishmania major using sodium dodecyl sulfate-polyacrylamide gel electrophoresis

    Directory of Open Access Journals (Sweden)

    Reza Arjmand

    2015-01-01

    Full Text Available Background: Leishmania is a parasitic protozoan of trypanosomatidae family which causes a wide spectrum of diseases ranging from self-healing cutaneous lesions to deadly visceral forms. In endemic areas, field trials of different preparations of Leishmania total antigen were tested as leishmaniasis vaccine. Two preparations of killed Leishmania major were produced In Iran, which were heat-killed vaccine called autoclaved L. major (ALM and thimerosal-treated freeze-thawed vaccine called killed L. major (KLM. In this study, the protein content of both ALM and KLM were compared with that of freshly harvested intact L. major promastigotes using sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE. Materials and Methods: L. major (MRHO/IR/75/ER from pre-infected Balb/c mice was isolated with modified Novy-MacNeal-Nicolle (NNN medium and then subcultured in liquid RPMI 1640 medium supplemented with fetal calf serum (FCS 20% for mass production. Two preparations of KLM and ALM were produced by Razi Vaccine and Serum Research Institute, Iran, under WHO/TDR supervision. Electrophoresis was performed by SDS-PAGE method and the gel was stained by Coomassie brilliant blue dye. The resultant unit bands were compared using standard molecular proteins. Results: Electrophoresis of the two preparations produced many bands from 10 kDa to 100 kDa. KLM bands were much like those of freshly harvested intact L. major. Conclusion: It is concluded that although there are similar bands in the three forms of Leishmania antigens, there are some variations which might be considered for identification and purification of protective immunogens in a total crude antigen, and detection of their stability is essential for the production and marketing of a putative vaccine.

  3. Serum sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis of patients with membranous nephropathy and focal and segmental glomerulosclerosis

    Directory of Open Access Journals (Sweden)

    Pragya Pant

    2016-01-01

    Full Text Available Diagnosis of membranous nephropathy (MN and focal and segmental glomerulo- sclerosis (FSGS needs a renal biopsy, which is an invasive procedure with potentially serious complications. Proteomics may be applied for the development of a biomarker for these diseases which will obviate the need of biopsy. Serum sodium dodecyl sulfate-polyacrylamide gel electro-phoresis (SDS-PAGE analysis gives an idea of the various proteins with different molecular weights (MWs in a given sample. This study was conducted to analyze proteins with different MWs in patients with MN and FSGS and to compare the two groups with regard to their protein profile. This was a comparative, experimental study performed from June 2013 to July 2014 in the Department of Nephrology, Sir Sunderlal Hospital, Banaras Hindu University, Varanasi. Twenty-three histologically diagnosed cases of primary MN and 25 cases of FSGS were included in the study. Patients were categorized as having mild, moderate, and severe proteinuria with 24 h urinary protein levels of <4, 4- 8 and ≥8 g/24 h, respectively. SDS-PAGE analysis was performed by the method of Laemmli and revealed a significantly higher number of patients with FSGS (80% having a protein corresponding to 29 kDa MW, than those with MN (39.1% (P = 0.004. Protein of 5 kDa MW was present in a significantly higher number of patients with moderate (80% and severe (100% proteinuria than those with mild proteinuria (25% (P <0.001. Thus, protein of MW 29 kDa may be a marker for FSGS and needs further characterization. Similarly, 5 kDa protein, present in patients with moderate and severe proteinuria, might be either contributing to or be a marker of severe illness.

  4. Serum sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis of patients with membranous nephropathy and focal and segmental glomerulosclerosis.

    Science.gov (United States)

    Pant, Pragya; Singh, R G; Singh, Santosh K; Singh, Vijay P; Doley, Prodip K; Sivasankar, M

    2016-05-01

    Diagnosis of membranous nephropathy (MN) and focal and segmental glomerulo- sclerosis (FSGS) needs a renal biopsy, which is an invasive procedure with potentially serious complications. Proteomics may be applied for the development of a biomarker for these diseases which will obviate the need of biopsy. Serum sodium dodecyl sulfate-polyacrylamide gel electro-phoresis (SDS-PAGE) analysis gives an idea of the various proteins with different molecular weights (MWs) in a given sample. This study was conducted to analyze proteins with different MWs in patients with MN and FSGS and to compare the two groups with regard to their protein profile. This was a comparative, experimental study performed from June 2013 to July 2014 in the Department of Nephrology, Sir Sunderlal Hospital, Banaras Hindu University, Varanasi. Twenty-three histologically diagnosed cases of primary MN and 25 cases of FSGS were included in the study. Patients were categorized as having mild, moderate, and severe proteinuria with 24 h urinary protein levels of <4, 4- 8 and ≥8 g/24 h, respectively. SDS-PAGE analysis was performed by the method of Laemmli and revealed a significantly higher number of patients with FSGS (80%) having a protein corresponding to 29 kDa MW, than those with MN (39.1%) (P = 0.004). Protein of 5 kDa MW was present in a significantly higher number of patients with moderate (80%) and severe (100%) proteinuria than those with mild proteinuria (25%) (P <0.001). Thus, protein of MW 29 kDa may be a marker for FSGS and needs further characterization. Similarly, 5 kDa protein, present in patients with moderate and severe proteinuria, might be either contributing to or be a marker of severe illness.

  5. Aplikasi Metode SDS-PAGE (Sodium Dodecyl Sulphate Poly Acrylamide Gel Electrophoresis untuk Mengidentifikasi Sumber Asal Gelatin pada Kapsul Keras

    Directory of Open Access Journals (Sweden)

    Sandra Hermanto

    2016-08-01

    Full Text Available Gelatin as the main ingredient of capsules is still a problem for a moslem. Most of gelatin production remains largely derived from non-halal materials. One of gelatin source is came from collagen of the skin and bones of bovine or pork. The main of study is determine the source of gelatin used in hard capsules by using SDS-PAGE (Sodium Dodecyl Sulphate Gel electrophoresis Poly Acrylamide method. In the early stages, optimization of standards bovine and pork gelatin were hydrolyzed by pepsin at pH 4.5 and 60°C for 1 hour, 2 hours, and 3 hours. Gelatin hydrolyzateswere analyzed by SDS-PAGE to determine the optimal hydrolysis time. Identification of gelatin hydrolyzate fragments were carried by molecular weight. Hydrolysis time optimization throught applied to identify the source of hard gelatin capsules in the samples obtained from market and compared with the simulation of hard gelatin capsules. The results showed there were of specific bands of bovine gelatin with a molecular weight of 11,4 kDa; 34 kDa; 47kDa and specific bands of pork gelatin with a molecular weight of 24.7 kDa; 28 kDa; and 60 kDa. Similar results were obtained on a sample of hard capsules with bands of protein fragments that were identical to bovine gelatinstandard. Based on the results,each of the samples were tested contain of bovine gelatin respectively. DOI :http://dx.doi.org/10.15408/jkv.v0i0.3150

  6. Effect of Sodium Dodecyl Sulfate (SDS) and Tween 80 on Cell Viability in an Air-Cathode Microbial Fuel Cell

    KAUST Repository

    Fregoso, Luisa

    2011-07-01

    Microbial fuel cells (MFCs) generate current via electrochemical reactions produced by bacteria attached to the anode that oxidize organic matter. Due to their high volume use in household products, some concentration of surfactant will reach wastewater treatment plants. The average surfactant concentration in wastewater ranges from 10 to 20 mg L-1, and up to 300 mg L-1, for domestic and industrial wastewaters, respectively. This study aimed to demonstrate the feasibility of enhancing power production by adding Tween 80 and SDS surfactants to air-cathode MFCs, and their effect in cell viability at the anodic biofilm. In order to analyze the effect of anionic and nonionic surfactants in MFCs performance, eight MFCs were spiked with two types of surfactants, the anionic surfactant sodium dodecyl sulfate (SDS) and the nonionic surfactant Tween® 80 at two different concentrations 10 and 100 mg L-1. Cell viability at the anodic biofilms was examined using the LIVE/DEAD BacLight viability assay and images were visualized with a confocal laser scanning microscope. The electrochemical results demonstrate that, for an air-cathode MFC operating on 1 g L-1 acetate in a fed-batch mode, reactors where SDS was added show a lower overall performance, maximum PD of 544 mW m-2, CE of 12.3%, Rint of 322 Ω (10 mg L-1) and maximum PD of 265 mW m-2, CE of 9.4%, Rint of 758 Ω (100 mg L-1). Reactors where Tween 80 was added show quite stable performance, maximum PD of 623 mW m-2, CE of 15.4%, Rint of 216 Ω (10 mg L-1) and maximum PD of 591 mW m-2, CE of 10.8%, Rint of 279 Ω (100 mg L-1), compared with reactors operating at only acetate as a substrate, maximum PD of 574 mW m-2. Confocal microscopy images confirm this observation and biofilm viability appeared severely compromised in SDS reactors, especially at high concentrations. This study has opened up a whole new research area in determining which types of surfactants are toxic to the anodic biofilm and to further investigate the

  7. Preparation of the cactus-like porous manganese oxide assisted with surfactant sodium dodecyl sulfate for supercapacitors

    Energy Technology Data Exchange (ETDEWEB)

    Dai, Yu [State Key Laboratory of Advanced Metallurgy, University of Science and Technology Beijing, No. 30 College Road, Beijing 100083 (China); Li, Jianling, E-mail: lijianling@ustb.edu.cn [State Key Laboratory of Advanced Metallurgy, University of Science and Technology Beijing, No. 30 College Road, Beijing 100083 (China); Yan, Gang; Xu, Guofeng; Xue, Qingrui [State Key Laboratory of Advanced Metallurgy, University of Science and Technology Beijing, No. 30 College Road, Beijing 100083 (China); Kang, Feiyu [Lab of Advanced Materials, Department of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China)

    2015-02-05

    Highlights: • The cactus-like porous MnO{sub 2} was synthesized by hydrothermal method assisted with SDS. • The MnO{sub 2} exhibits a max specific capacitance of 187.8 F g{sup −1} (0.2 A g{sup −1}, 1 M Na{sub 2}SO{sub 4}). • Excellent cycling stability: 92.9% capacitance retention after 1000 cycles. - Abstract: The cactus-like porous manganese dioxide (MnO{sub 2}) was synthesized by a simple hydrothermal method assisted with the surfactant sodium dodecyl sulfate (SDS). The morphology, composition, property of the prepared materials were characterized by X-ray diffraction (XRD), Raman spectroscopy, Brunauer–Emmett–Teller (BET), Field Emission Scanning Electron Microscopy (FE-SEM) and Transmission Electron Microscopy (TEM) measurements. It was found that the sample without surfactant was composed of nanoflakes which piling up together, whereas in the presence of the surfactant, the MnO{sub 2} samples with the max specific surface of 321.9 m{sup 2} g{sup −1} showed a porous cactus-like microstructure, consisted of uniform nanowires and porous nanoflakes. The electrochemical performances of the MnO{sub 2} with and without surfactant were analyzed using Cyclic Voltammetry (CV), Electrochemical Impedance Spectrometry (EIS) and Galvanostatic Charge–Discharge (GCD) tests. The results showed that the MnO{sub 2} assisted with 1 wt.% SDS displayed a higher specific capacitance of 187.8 F g{sup −1} at the current density of 0.2 A g{sup −1} compared with the MnO{sub 2} without surfactant (134.8 F g{sup −1}). And such MnO{sub 2} samples with higher specific capacitance also afford an excellent cyclic stability with the capacity retention of approximately 92.9% after 1000 cycles in 1 M Na{sub 2}SO{sub 4} solution at a current density of 1 A g{sup −1}. The superior capacitive performance of the as-prepared materials could be attributed to its unique cactus-like porous structure, which provided good electronic conductivity, large specific surface area as

  8. Analysis of Soluble Proteins in Natural Cordyceps sinensis from Different Producing Areas by Sodium Dodecyl Sulfate-Polyacrylamide Gel Electrophoresis and Two-dimensional Electrophoresis.

    Science.gov (United States)

    Li, Chun-Hong; Zuo, Hua-Li; Zhang, Qian; Wang, Feng-Qin; Hu, Yuan-Jia; Qian, Zheng-Ming; Li, Wen-Jia; Xia, Zhi-Ning; Yang, Feng-Qing

    2017-01-01

    As one of the bioactive components in Cordyceps sinensis (CS), proteins were rarely used as index components to study the correlation between the protein components and producing areas of natural CS. Protein components of 26 natural CS samples produced in Qinghai, Tibet, and Sichuan provinces were analyzed and compared to investigate the relationship among 26 different producing areas. Proteins from 26 different producing areas were extracted by Tris-HCl buffer with Triton X-100, and separated using sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and two-dimensional electrophoresis (2-DE). The SDS-PAGE results indicated that the number of protein bands and optical density curves of proteins in 26 CS samples was a bit different. However, the 2-DE results showed that the numbers and abundance of protein spots in protein profiles of 26 samples were obviously different and showed certain association with producing areas. Based on the expression values of matched protein spots, 26 batches of CS samples can be divided into two main categories (Tibet and Qinghai) by hierarchical cluster analysis. The number of protein bands and optical density curves of proteins in 26 Cordyceps sinensis samples were a bit different on the sodium dodecyl sulfate-polyacrylamide gel electrophoresis protein profilesNumbers and abundance of protein spots in protein profiles of 26 samples were obvious different on two-dimensional electrophoresis mapsTwenty-six different producing areas of natural Cordyceps sinensis samples were divided into two main categories (Tibet and Qinghai) by Hierarchical cluster analysis based on the values of matched protein spots. Abbreviations Used: SDS-PAGE: Sodium dodecyl sulfate polyacrylamide gel electrophoresis, 2-DE: Two-dimensional electrophoresis, Cordyceps sinensis: CS, TCMs: Traditional Chinese medicines.

  9. Determination of amino acid compositions and NH2-terminal sequences of peptides electroblotted onto PVDF membranes from tricine-sodium dodecyl sulfate-polyacrylamide gel electrophoresis

    DEFF Research Database (Denmark)

    Ploug, M; Jensen, A L; Barkholt, V.

    1989-01-01

    The combination of high-resolution Tricine-Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (H. Schägger and G. von Jagow (1987) Anal. Biochem. 166, 368-379) and electroblotting onto polyvinylidene difluoride (PVDF) membranes represents a powerful technique for the isolation of small...... amounts of peptides and protein fragments (Mr 1000-20,000) in a suitable form for amino acid sequencing, directly on the blotting membrane. Conditions for electrophoresis and electroblotting were optimized with respect to high transfer yield and suitability for both amino acid analysis and sequence...

  10. Isoelectric focusing of human hair keratins: correlation with sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) patterns and effect of cosmetic treatments.

    Science.gov (United States)

    Rodriguez-Calvo, M S; Carracedo, A; Muñoz, I; Concheiro, L

    1992-03-01

    A new isoelectric focusing (IEF) technique in polyacrylamide gels with 6M urea and 1.5% Nonidet P40 has been developed to characterize human hair samples. The phenotypes demonstrated with this procedure has been correlated with the sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) patterns described by other authors. The method described can be applied in the forensic science analysis of a single human hair. Using the same IEF technique we have studied the changes in electrophoretic patterns of cosmetically treated hair. The characteristics of the modifications observed and its utility in forensic science work are also discussed in this paper.

  11. Adsorption of the anionic surfactant sodium dodecyl sulfate on a C18 column under micellar and high submicellar conditions in reversed-phase liquid chromatography.

    Science.gov (United States)

    Ortiz-Bolsico, C; Ruiz-Angel, M J; García-Alvarez-Coque, M C

    2015-02-01

    Micellar liquid chromatography makes use of aqueous solutions or aqueous-organic solutions containing a surfactant, at a concentration above its critical micelle concentration. In the mobile phase, the surfactant monomers aggregate to form micelles, whereas on the surface of the nonpolar alkyl-bonded stationary phases they are significantly adsorbed. If the mobile phase contains a high concentration of organic solvent, micelles break down, and the amount of surfactant adsorbed on the stationary phase is reduced, giving rise to another chromatographic mode named high submicellar liquid chromatography. The presence of a thinner coating of surfactant enhances the selectivity and peak shape, especially for basic compounds. However, the risk of full desorption of surfactant is the main limitation in the high submicellar mode. This study examines the adsorption of the anionic surfactant sodium dodecyl sulfate under micellar and high submicellar conditions on a C18 column, applying two methods. One of them uses a refractive index detector to obtain direct measurements of the adsorbed amount of sodium dodecyl sulfate, whereas the second method is based on the retention and peak shape for a set of cationic basic compounds that indirectly reveal the presence of adsorbed monomers of surfactant on the stationary phase.

  12. Interactions between sodium dodecyl sulphate and non-ionic cellulose derivatives studied by size exclusion chromatography with online multi-angle light scattering and refractometric detection.

    Science.gov (United States)

    Wittgren, Bengt; Stefansson, Morgan; Porsch, Bedrich

    2005-08-05

    The novel approach described allows to characterise the surfactant-polymer interaction under several sodium dodecyl sulphate (SDS) concentrations (0-20 mM) using size exclusion chromatography (SEC) with online multi-angle light scattering (MALS) and refractometric (RI) detection. Three different cellulose derivatives, hydroxypropyl cellulose (HPC), hydroxypropyl methyl cellulose (HPMC) and hydroxyethyl cellulose (HEC), have been studied in solution containing 10 mM NaCl and various concentrations of sodium dodecyl sulphate. It is shown that this approach is well suited for successful application of both Hummel-Dreyer and multi-component light scattering principles and yields reliable molecular masses of both the polymer complex and the polymer itself within the complex, the amount of surfactant bound into the complex as well as appropriate values of the refractive index increment (dn/dc)micro, of both the complex and the polymer in question. The more hydrophobic derivatives HPC and HPMC adsorbed significantly more SDS than HEC. The inter-chain interactions close to critical aggregation concentration (cac) were clearly seen for HPC and HPMC as an almost two-fold average increase in polymer molecular mass contained in the complex.

  13. Method development for cortisol and cortisone by micellar liquid chromatography using sodium dodecyl sulphate: application to urine samples of rugby players.

    Science.gov (United States)

    Izquierdo-Hornillos, R; Gonzalo-Lumbreras, R; Santos-Montes, A

    2005-01-01

    The chromatographic behavior of cortisol and cortisone using a micellar medium of sodium dodecyl sulphate (SDS) as surfactant, a Hypersil C18 (150- x 3.2-mm i.d., 5 microm) column, a flow rate of 0.5 mL/min, and UV absorbance detection at 245 nm is described. The effect of several organic modifiers and the surfactant concentration on the separation is studied. A mobile phase of 18 mM SDS and 8.3% tetrahydrofuran allows for the separation of cortisol and cortisone up to baseline. These results are also achieved by applying a bivariant optimization method. The proposed method is sensitive, reproducible, and selective. In addition, it is less expensive than conventional high-performance liquid chromatography methods for cortisol and cortisone. The method is applied to the determination of cortisol and cortisone in urine samples of rugby players before and after stress for doping control purposes.

  14. Micellar copolymerization of associative polymers: study of the effect of acrylamide on sodium dodecyl sulfate-poly(propylene oxide) methacrylate mixed micelles.

    Science.gov (United States)

    Bastiat, Guillaume; Grassl, Bruno; François, Jeanne

    2005-09-15

    Mixed micelles of sodium dodecyl sulfate (SDS) and poly(propylene oxide) methacrylate (PPOMA) have been studied in the presence of acrylamide using conductimetry, fluorescence spectroscopy, and small-angle neutron scattering (SANS) under the following conditions: (i) the SDS-acrylamide binary system in water; (ii) the SDS-acrylamide-PPOMA ternary system in water. The addition of acrylamide in SDS solutions perturbs the micellization of the surfactant by decreasing the aggregation number of the micelles and increasing their ionization degree. The variations of the various micellar parameters versus the weight ratio R=PPOMA/SDS are different in the presence of acrylamide or in pure water. These differences are much more pronounced for the lower than for the higher PPOMA concentrations. There is competition between acrylamide and PPOMA and at higher PPOMA concentration, acrylamide tends to be released from SDS micelles and is completely replaced by PPOMA.

  15. Conductometric study of sodium dodecyl sulfate - nonionic surfactant (Triton X-100, Tween 20, Tween 60, Tween 80 or Tween 85 mixed micelles in aqueous solution

    Directory of Open Access Journals (Sweden)

    Ćirin Dejan M.

    2012-01-01

    Full Text Available The present study is concerned with the determination of the critical micelle concentration (cmc of mixed micelles of sodium dodecyl sulfate with one of five nonionic surfactants (Triton X-100, Tween 20, Tween 60, Tween 80 or Tween 85 from conductance measurements. Based on the calculated values of the β parameters we have noticed that SDS-nonionic surfactants mostly showed strong synergistic effect. It was found that nonionic surfactants with mainly longer and more hydrophobic tail show stronger interactions with hydrophobic part of SDS, thus expressing stronger synergism. In SDS-Tween 80 binary system the strongest synergistic effect was noticed. SDS-Tween 85 micellar system showed antagonistic effect, most probably because the presence of the double bond in its three hydrophobic tails (three C18 tails makes it sterically rigid.

  16. Characterization of Sm14 related components in different helminths by sodium dodecyl sulphate-polyacrylamide gel electrophoresis and Western blotting analysis

    Directory of Open Access Journals (Sweden)

    Nilton Thaumaturgo

    2002-10-01

    Full Text Available Sm14 was the first fatty acid-binding protein homologue identified in helminths. Thereafter, members of the same family were identified in several helminth species, with high aminoacid sequence homology between them. In addition, immune crossprotection was also reported against Fasciola hepatica infection, in animals previously immunized with the Schistosoma mansoni vaccine candidate, r-Sm14. In the present study, data on preliminary sodium dodecyl sulphate-polyacrylamide gel electrophoresis and Western blotting analysis of nine different helminth extracts focusing the identification of Sm14 related proteins, is reported. Out of these, three extracts - Ascaris suum (males and females, Echinostoma paraensei, and Taenia saginata - presented components that comigrated with Sm14 in SDS-PAGE, and that were recognized by anti-rSm14 policlonal serum, in Western blotting tests.

  17. Interaction between sodium dodecyl sulfate and membrane reconstituted aquaporins: A comparative study of spinach SoPIP2;1 and E. coli AqpZ

    DEFF Research Database (Denmark)

    Hansen, Jesper Schmidt; Vararattanavech, Ardcharaporn; Plasencia, Inés;

    2011-01-01

    This study describes the interaction between sodium dodecyl sulfate (SDS) and membrane proteins reconstituted into large unilamellar lipid vesicles and detergent micelles studied by circular dichroism (CD) and polarity sensitive probe labeling. Specifically, we carried out a comparative study...... of two aquaporins with high structural homology SoPIP2;1 and AqpZ using identical reconstitution conditions. Our CD results indicate that SDS, when added to membrane-reconstituted aquaporins in concentrations below the SDS critical micelle concentration (CMC, ~8mM), causes helical rearrangements of both...... reconstituted SoPIP2;1 as well as AqpZ is associated with initial increased hydrophobic interactions in protein transmembrane (TM) spanning regions up to a concentration of 0.1× CMC. At higher SDS concentrations TM hydrophobic interactions, as reported by Badan, decrease and reach a plateau from SDS CMC up...

  18. Electrochemical deposition of Ni–TiN nanocomposite coatings and the effect of sodium dodecyl sulphate surfactant on the coating properties

    Indian Academy of Sciences (India)

    NAFISE PARHIZKAR; ABOLGHASEM DOLATI; ROYA AGHABABAZADEH; ZAHRA LALEGANI

    2016-08-01

    Ni–TiN nanocomposite coatings were prepared by using electrochemical deposition in a Watt’s bath containing TiN particles to increase the hardness of Ni. The effects of deposition current density, electrolyte agitation speed and the number of particles in the solution on the amount of incorporated particles in the coating process were investigated. The optimum deposition current density of 4 A dm$^{−2}$ and agitation speed of 450 rpm were obtained. The effect of sodium dodecyl sulphate (SDS) anionic surfactant on the amount of particles in the coatings was investigated. It was observed that the maximum amount of incorporated particles, with a value of 7.5% by volume, was created in the current density of 4 A dm$^{−2}$, stirring rate of 450 rpm, 30 g l$^{−1}$ TiN particles and in the presence of 0.6 g l$^{−1}$ SDS anionic surfactant.

  19. Synthesis of a new electrolyte by co-poly-esters doped with sodium dodecyl sulfate for application on PEM fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Fiuza, J.R.A.; Boaventura, F.J.S.; Jose, N.M.; Bresciani, D. [Univ. Federal da Bahia, Salvador (Brazil). Dept. of Physical Chemistry

    2009-07-01

    Proton exchange membrane fuel cells (PEMFCs) use polymer membranes as electrolytes and protons as conductors. This paper reported on a study in which co-polyesters were doped with sodium dodecyl sulfate. The co-polymers were synthesized by a copolymerization process that used terephthalic and adipic acids with glycerol. A reactor was used to process the material, which was then hot-pressed to produce homogenous and flexible plates. X-ray diffraction (XRD) scanning electron microscopy (SEM), thermogravimetric, direct scanning calorimetry (DSC) and Fourier Transform Infrared (FTIR) analyses were conducted. Results of the analyses demonstrated that the composite material was stable up to a temperature of 250 degrees C. A micrographics study showed that MDS was homogeneously dispersed in the polymeric matrix. It was concluded that with an electrical conductivity between 10-7 to 10-1 S per cm, the copolymers were suitable for use in PEMFC applications.

  20. Effect of sodium dodecyl sulfate on immuno-electrosyneresis between normal human erythrocyte membrane and sera of systemic lupus erythematosus patients

    Directory of Open Access Journals (Sweden)

    Arimori,Shigeru

    1975-12-01

    Full Text Available An anti-membrane antibody was present in the sera of systemic lupus erythematosus patients in immunoelectrosyneresis with sodium dodecyl sulfate (SDS solubilized erythrocyte membrane as antigen. The SDS bound to protein was detected by chromatography at 10(-3M concentration under U.V. light, at 10(-5M concentration by the distilled water spray method and at 10(-6M concentration by using rosaniline hydrochloride colorimetry. SDS was removed from the membrane protein at a concentration of 10(-3M by the first gel filtration of Sephadex G-25 column and at a concentration of 10(-6M by rechromatography of the same column. More than 99% of SDS in the solubilized erythrocyte membrane was removed by gel filtration. The antigenicity was still positive in the refiltrated fractions of systemic lupus erythematosus patients. Therefore, all precipitates in the gels were antigen-antibody aggregates.

  1. Fast Removal of Citalopram Drug from Waste Water Using Magnetic Nanoparticles Modified with Sodium Dodecyl Sulfate Followed by UV-Spectrometry

    Directory of Open Access Journals (Sweden)

    M. Khoeini Sharifabadi

    2014-02-01

    Full Text Available A simple and sensitive, solid-phase extraction method for the removal of Citalopram drug from waste water has been developed by using magnetic nanoparticles modified with surfactant sodium dodecyl sulfate. These magnetic nanoparticles have shown great adsorptive tendency towards Citalopram drug. The effect of different parameters influencing the extraction efficiency of this drug were investigated and optimized including the pH, amount of the surfactant, contact time and temperature. The extracts were analyzed by ultraviolet spectrophotometry at 239nm. Under these conditions, the related standard deviation (RSD % of the method at two concentrations (5 and 50µg.mL-1 was in the range of (3.14–3.75 % (n = 8. The calibration curve was linear in the range of 2-100 µg.mL-1 of Citalopram drug with a correlation coefficient of >0.99.

  2. Fast Removal of Citalopram Drug from Waste Water Using Magnetic Nanoparticles Modified with Sodium Dodecyl Sulfate Followed by UV-Spectrometry

    Directory of Open Access Journals (Sweden)

    M. Khoeini Sharifabadi

    2013-04-01

    Full Text Available A simple and sensitive, solid-phase extraction method for the removal of Citalopram drug from waste water has been developed by using magnetic nanoparticles modified with surfactant sodium dodecyl sulfate. These magnetic nanoparticles have shown great adsorptive tendency towards Citalopram drug. The effect of different parameters influencing the extraction efficiency of this drug were investigated and optimized including the pH, amount of the surfactant, contact time and temperature. The extracts were analyzed by ultraviolet spectrophotometry at 239nm. Under these conditions, the related standard deviation (RSD % of the method at two concentrations (5 and 50µg.mL-1 was in the range of (3.14–3.75 % (n = 8. The calibration curve was linear in the range of 2-100 µg.mL-1 of Citalopram drug with a correlation coefficient of >0.99.

  3. The Effect of Sodium Dodecyl Sulfate (SDS and Cetyltrimethylammonium Bromide (CTAB on the Properties of ZnO Synthesized by Hydrothermal Method

    Directory of Open Access Journals (Sweden)

    Yun Hin Taufiq-Yap

    2012-10-01

    Full Text Available ZnO nanostructures were synthesized by hydrothermal method using different molar ratios of cetyltrimethylammonium bromide (CTAB and Sodium dodecyl sulfate (SDS as structure directing agents. The effect of surfactants on the morphology of the ZnO crystals was investigated by field emission scanning electron microscopy (FESEM and transmission electron microscopy (TEM techniques. The results indicate that the mixture of cationic-anionic surfactants can significantly modify the shape and size of ZnO particles. Various structures such as flakes, sheets, rods, spheres, flowers and triangular-like particles sized from micro to nano were obtained. In order to examine the possible changes in other properties of ZnO, characterizations like powder X-ray diffraction (PXRD, thermogravimetric and differential thermogravimetric analysis (TGA-DTG, FTIR, surface area and porosity and UV-visible spectroscopy analysis were also studied and discussed.

  4. Comparison of microenvironments of aqueous sodium dodecyl sulfate micelles in the presence of inorganic and organic salts: a time-resolved fluorescence anisotropy approach.

    Science.gov (United States)

    Dutt, G B

    2005-11-08

    Microenvironments of aqueous sodium dodecyl sulfate (SDS) micelles was examined in the presence of additives such as sodium chloride and p-toluidine hydrochloride (PTHC) by monitoring the fluorescence anisotropy decays of two hydrophobic probes, 2,5-dimethyl-1,4-dioxo-3,6-diphenylpyrrolo[3,4-c]pyrrole (DMDPP) and coumarin 6 (C6). It has been well-established that SDS micelles undergo a sphere-to-rod transition and that their mean hydrodynamic radius increases from 19 to 100 A upon the addition of 0.0-0.7 M NaCl at 298 K. A similar size and shape transition is induced by PTHC at concentrations that are 20 times lower compared to that of NaCl. This study was undertaken to find out how the microviscosity of the micelles is influenced under these circumstances. It was noticed that the microviscosity of the SDS/NaCl system increased by approximately 45%, whereas there was a less than 10% variation in the microviscosity of the SDS/PTHC system. The large increase in the microviscosity of the former system with salt concentration has been rationalized on the basis of the high concentration of sodium ions in the headgroup region of the micelles and their ability to strongly coordinate with the water present in this region, which decreases the mobility of the probe molecules.

  5. Development of a sodium dodecyl sulfate-polyacrylamide gel electrophoresis reference method for the analysis and identification of fish species in raw and heat-processed samples : A collaborative study

    DEFF Research Database (Denmark)

    Pineiro, C.; Barros-Velazquez, J.; Perez-Martin, R.I.;

    1999-01-01

    A collaborative study was carried out in seven European labs with the aim of achieving a sodium dodecyl sulfate- polyacrylamide gel electrophoresis (SDS-PAGE) standard operation procedure to identify fish species in raw and cooked samples. Urea and SDS-containing solutions were evaluated as extra...

  6. Development of a sodium dodecyl sulfate-polyacrylamide gel electrophoresis reference method for the analysis and identification of fish species in raw and heat-processed samples : A collaborative study

    DEFF Research Database (Denmark)

    Pineiro, C.; Barros-Velazquez, J.; Perez-Martin, R.I.

    1999-01-01

    A collaborative study was carried out in seven European labs with the aim of achieving a sodium dodecyl sulfate- polyacrylamide gel electrophoresis (SDS-PAGE) standard operation procedure to identify fish species in raw and cooked samples. Urea and SDS-containing solutions were evaluated as extra...

  7. Evaluation of DLVO theory with disjoining-pressure and film-conductance measurements of common-black films stabilized with sodium dodecyl sulfate.

    Science.gov (United States)

    Yaros, Heather D; Newman, John; Radke, C J

    2003-06-15

    We develop a unique film holder combining a thin-film balance with AC impedance spectroscopy to measure disjoining pressure, film conductance, and film thickness simultaneously. Foam films stabilized by sodium dodecyl sulfate (SDS) are investigated with and without added sodium chloride (NaCl) electrolyte. Classical colloidal theory, Derjaguin, Landau, Verwey, and Overbeek (DLVO) theory, is tested rigorously over a wide range of solution conditions by comparing the surface charge densities fit to disjoining-pressure isotherms with those estimated independently from film-conductance and surface-tension data. Film-conductance measurements strongly suggest that the adsorbed anionic surfactant is partially complexed with counterions. Therefore, to reconcile the different values of charge densities calculated from surface tension and film conductance with those from disjoining pressure, we propose a simple ion-binding electrostatic model. The ion-complexation framework predicts increased ion complexing with increasing solution ionic strength, in agreement with surface-tension and film-conductance data. Unfortunately, it is not possible to describe similarly the trends of the measured disjoining-pressure isotherms because the diffuse-layer charge density increases, or equivalently, the ion complexation decreases with increasing ionic strength. Accordingly, the ion-binding extension of classical DLVO theory does not permit agreement between theory and independent experimental data from surface tension, disjoining pressure, and film conductance.

  8. Detection of the End Point Temperature of Thermal Denatured Protein in Fish and Chicken Meat Through SDS-PAGE Electrophoresis

    Institute of Scientific and Technical Information of China (English)

    GAO Hongwei; MAO Mao; LIANG Chengzhu; LIN Chao; XIANG Jianhai

    2009-01-01

    Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) was applied in the detection of the end point temperature (EPT) of thermal denatured protein in fish and meat in this study. It was also used in studying the thermal denatured temperature range of proteins in salmon and chicken meat. The results show that the temperature ranges of denatured proteins were from 65℃ to 75℃, and these temperature ranges were influenced by the processing methods. Through SDS-PAGE, the features of repeated heating thermal denatured proteins under the same temperature and processing time were studied. The electrophoresis pat-terns of thermal denatured proteins determined through repeated heating at the same temperature did not exhibit any change. For the detection of cooked fish and meat samples, they were subjected to applying the SDS-PAGE method, which revealed an EPT ranging from 60℃ to 80℃.

  9. In-tube magnetic solid phase microextraction of some fluoroquinolones based on the use of sodium dodecyl sulfate coated Fe3O4 nanoparticles packed tube.

    Science.gov (United States)

    Manbohi, Ahmad; Ahmadi, Seyyed Hamid

    2015-07-23

    In-tube magnetic solid phase microextraction (in-tube MSPME) of fluoroquinolones from water and urine samples based on the use of sodium dodecyl sulfate (SDS) coated Fe3O4 nanoparticles packed tube has been reported. After the preparation of Fe3O4 nanoparticles (NPs) by a batch synthesis, these NPs were introduced into a stainless steel tube by a syringe and then a strong magnet was placed around the tube, so that the Fe3O4 NPs were remained in the tube and the tube was used in the in-tube SPME-HPLC/UV for the analysis of fluoroquinolones in water and urine samples. Plackett-Burman design was employed for screening the variables significantly affecting the extraction efficiency. Then, the significant factors were more investigated by Box-Behnken design. Calibration curves were linear (R(2)>0.990) in the range of 0.1-1000μgL(-1) for ciprofloxacin (CIP) and 0.5-500μgL(-1) for enrofloxacin (ENR) and ofloxacin (OFL), respectively. LODs for all studied fluoroquinolones ranged from 0.01 to 0.05μgL(-1). The main advantages of this method were rapid and easy automation and analysis, short extraction time, high sensitivity, possibility of fully sorbent collection after analysis, wide linear range and no need to organic solvents in extraction. Copyright © 2015 Elsevier B.V. All rights reserved.

  10. Effect of Sodium Dodecyl Sulfate Adsorption on the Behavior of Water inside Single Walled Carbon Nanotubes with Dissipative Particle Dynamics Simulation

    Directory of Open Access Journals (Sweden)

    Minh D. Vo

    2016-04-01

    Full Text Available Dissipative particle dynamics (DPD simulations were utilized to investigate the ability of sodium dodecyl sulfate (SDS to adsorb inside a single-walled, arm-chair carbon nanotube (SWCNT, as well as the effect of surfactant on the properties of water inside the SWCNT. The diameter of the SWCNT varied from 1 to 5 nm. The radial and axial density profiles of water inside the SWCNTs were computed and compared with published molecular dynamics results. The average residence time and diffusivity were also calculated to show the size effect on mobility of water inside the SWCNT. It was found that nanotubes with diameter smaller than 3 nm do not allow SDS molecules to enter the SWCNT space. For larger SWCNT diameter, SDS adsorbed inside and outside the nanotube. When SDS was adsorbed in the hollow part of the SWCNT, the behavior of water inside the nanotube was found to be significantly changed. Both radial and axial density profiles of water inside the SWCNT fluctuated strongly and were different from those in bulk phase. In addition, SDS molecules increased the retention of water beads inside SWCNT (d ≥ 3nm while water diffusivity was decreased.

  11. Structural and phase transition changes of sodium dodecyl sulfate micellar solution in alcohols probed by small-angle neutron scattering (SANS)

    Energy Technology Data Exchange (ETDEWEB)

    Putra, Edy Giri Rachman [Neutron Scattering Laboratory, National Nuclear Energy Agency of Indonesia (BATAN), Gedung 40 BATAN, Kawasan Puspiptek Serpong, Tangerang 15314 (Indonesia); Patriati, Arum [Neutron Scattering Laboratory, National Nuclear Energy Agency of Indonesia (BATAN), Gedung 40 BATAN, Kawasan Puspiptek Serpong, Tangerang 15314 (Indonesia); Department of Chemistry, Faculty of Mathematics and Natural Sciences, University of Gadjah Mada, Bulaksumur, Yogyakarta 55281, Indonesia giri@batan.go.id (Indonesia)

    2015-04-16

    Small-angle neutron scattering (SANS) measurements on 0.3M sodium dodecyl sulfate (SDS) micellar solutions have been performed in the presence of n-alcohols, from ethanol to decanol at different alcohol concentrations, 2–10 wt%. The ellipsoid micellar structure which occurred in the 0.3M SDS in aqueous solution with the size range of 30–50 Å has different behavior at various hydrocarbon chain length and concentration of alcohols. At low concentration and short chain-length of alcohols, such as ethanol, propanol, and butanol, the size of micelles reduced and had a spherical-like structure. The opposite effect occurred as medium to long chain alcohols, such as hexanol, octanol and decanol was added into the 0.3M SDS micellar solutions. The micelles structure changed to be more elongated in major axis and then crossed the critical phase transition from micellar solution into liquid crystal phase as lamellar structure emerged by further addition of alcohols. The inter-lamellar distances were also depending on the hydrocarbon chain length and concentration of alcohols. In the meantime, the persistent micellar structures occurred in addition of medium chain of n-alcohol, pentanol at all concentrations.

  12. Sodium dodecyl sulfate coated γ-alumina support modified by a new Schiff base for solid phase extraction and flame-AAS determination of lead and copper ions

    Directory of Open Access Journals (Sweden)

    Ardeshir Shokrollahi

    2013-01-01

    Full Text Available A simple and fast approach for solid phase extraction is herein described, and used to determine trace amounts of Pb2+ and Cu2+ metal ions. The solid phase support is sodium dodecyl sulfate (SDS-coated γ-alumina modified with bis(2-hydroxy acetophenone-1,6-hexanediimine (BHAH ligand. The adsorbed ions were stripped from the solid phase by 6 mL of 4 M nitric acid as eluent. The eluting solution was analyzed by flame atomic absorption spectrometry (FAAS. The sorption recovery of metal ions was investigated with regard to the effects of pH, amount of ligand, γ-alumina and surfactant and the amount and type of eluent. Complexation of BHAH with Pb2+ or Cu2+ ions was examined via spectrophotometry using the HypSpec program. The detection limit for Cu2+ was 7.9 µg L-1 with a relative standard deviation of 1.67%, while that for Pb2+ was 6.4 µg L-1 with a relative standard deviation of 1.64%. A preconcentration factor of 100 was achieved for these ions. The method was successfully applied to determine analyte concentrations in samples of liver, parsley, cabbage, and water.

  13. Micellization, interaction and thermodynamic study of butylated hydroxyanisole (synthetic antioxidant and sodium dodecyl sulfate in aqueous-ethanol solution at 25, 30 and 35 °C

    Directory of Open Access Journals (Sweden)

    Varun Bhardwaj

    2016-09-01

    Full Text Available Surfactants are found to enhance the diffusion significantly depending on hydrophobic/hydrophilic group lengths and the structure of the surfactant molecule. Aggregation properties of sodium dodecyl sulfate (SDS in the presence of butylated hydroxyanisole (synthetic antioxidant, at a range of temperatures (25, 30 and 35 °C have been measured by the conductometric study in aqueous-ethanolic composite solution. The experimental data of aqueous-ethanolic solutions as a function of SDS concentration ranging from 1 to 14 mM dm−3 show the presence of inflexion points indicating micellization and interaction mechanisms. Effect of temperature was also observed in increasing the CMC (Critical Micelle Concentration in the narrow composition. From the CMC values as a function of temperature, various thermodynamic parameters have been evaluated viz: (a the standard enthalpy change (ΔHm°, (b standard entropy change (ΔSm°, and (c standard Gibbs energy change (ΔGm°. The results showed that the presence of alcohol, as well as the composition of water + ethanol may have effect on thermodynamic parameters. The variation in these parameters with the concentration of surfactant or with the change in temperature suggests the manifestation of hydrophobic interactions in the studied system.

  14. Effects of Sodium Dodecyl Sulfate on Electroless Nickel Plating%十二烷基硫酸钠对化学镀镍的影响

    Institute of Scientific and Technical Information of China (English)

    线东升; 李喜太; 李艳玲

    2012-01-01

    Sodium dodecyl sulfate is an indispensable pinhole preventive in the electroless nickel plating. During the electroless nickel plating process, white attachments can be easily produced on the surface of larger solid steel parts, which affects the quality of electroless nickel plating. But no white attachments were found on the surface of test pieces in the same plating bath. The producing reasons and solving methods of the produced white attachments have been found after years of exploration and analysis.%十二烷基硫酸钠是化学镀镍不可缺少的防针孔剂,较大实心钢铁零件化学镀镍过程中,很容易在零件表面产生白色附着物,影响化学镀镍的质量,而在同一镀槽的化学镀镍试片表面不产生白色附着物;经过多年的探索和分析,找到了白色附着物产生的原因和解决方法.

  15. Effects of sodium dodecyl benzene sulfonate on the crystal structures and photocatalytic performance of ZnO powders prepared by hydrothermal method

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Limin; Dong, Shuying; Li, Qilu; Li, Yifan; Pi, Yunqing; Liu, Menglin; Han, Xiao; Sun, Jianhui, E-mail: sunjh@htu.cn

    2015-11-15

    A facile and efficient route for the controllable synthesis of ZnO nanostructures by hydrothermal method using sodium dodecyl benzene sulfonate (SDBS) as surfactant was reported. The obtained products were well characterized with the aid of various techniques to probe their crystallographic, morphological, chemical, electrochemical and optical properties. The prepared products were used as photocatalysts in the application of the degradation of metronidazole (MNZ)-contained wastewater under visible light irradiation. A 4.5-fold augmentation of degradation efficiency was in turn observed for optimal ZnO (ZO-0.75) photocatalyst compared with that of sample without SDBS addition (ZO) under the visible light irradiation. The effects of SDBS dosage on the crystal structures of prepared samples as well as the crystal growth mechanism were also probed. - Graphical abstract: ZnO photocatalysts were fabricated through a facile and efficient hydrothermal method using SDBS as structure-directing surfactant in a controllable manner. In particular, the sample with different SDBS dosage exhibited distinct crystal structure and photocatalytic performance. - Highlights: • A rod-like ZnO photocatalyst was facilely synthesized by using SDBS as surfactant. • The effect of SDBS dosage on the crystal structure of photocatalyst was probed. • The probably crystal growth mechanism of prepared photocatalyst was explored. • The optimal ZnO with 0.75 g SDBS dosage displayed the best photocatalytic activity.

  16. ADSORPTION STUDY OF RHODAMIN B DYE ON IRAQI BENTONITE AND MODIFIED BENTONITE BY NANOCOMPOUNDS TIO2, ZNO, AL2O3 AND SODIUM DODECYL SULFATE

    Directory of Open Access Journals (Sweden)

    Iqbal Salman AL-Jobouri

    2013-01-01

    Full Text Available The adsorption of Rhodamin B on Iraqi bentonite at the concentration range from 50 to 250 μg mL-1 was studied, Nano compounds; ZnO, TiO2, Al2O3 m and SDS in different amounts 0.01-0.1 g 10-1 g of Bentonite were used to modified the adsorption capacity of bentonite to remove the Rhodamin B from aqueous solutions. The study indicated that using 0.05 g and 0.1 of Sodium Dodecyl Sulfate (SDS lead to increase the percentage removal (%R from 79.3% for pure bentonite to 99.3%. While using 0.05 g TiO2 lead to increase the %R to 98.9%, 0.05 of ZnO to 98.6%. The other amount additives and Al2O3 using was not success to increase the %R for the Rhodamin B on bentonite surface. SEM measurement was achieved to discover the Nanoparticl exists in the bentonite surfaces.

  17. Temperature-dependent phase transition and desorption free energy of sodium dodecyl sulfate at the water/vapor interface: approaches from molecular dynamics simulations.

    Science.gov (United States)

    Chen, Meng; Lu, Xiancai; Liu, Xiandong; Hou, Qingfeng; Zhu, Youyi; Zhou, Huiqun

    2014-09-09

    Adsorption of surfactants at the water/vapor interface depends upon their chemical potential at the interface, which is generally temperature-dependent. Molecular dynamics simulations have been performed to reveal temperature influences on the microstructure of sodium dodecyl sulfate (SDS) molecule adsorption layer. At room temperature, SDS molecules aggregate at the interface, being in a liquid-expanded phase, whereas they tend to spread out and probably transit to a gaseous phase as the temperature increases to above 318 K. This phase transition has been confirmed by the temperature-dependent changes in two-dimensional array, tilt angles, and immersion depths to the aqueous phase of SDS molecules. The aggregation of SDS molecules accompanies with larger immersion depths, more coordination of Na(+) ions, and less coordination of water. Desorption free energy profiles show that higher desorption free energy appears for SDS molecules at the aggregate state at low temperatures, but no energy barrier is observed. The shapes of desorption free energy profiles depend upon the distribution of SDS at the interface, which, in turn, is related to the phase state of SDS. Our study sheds light on the development of adsorption thermodynamics and kinetics theories.

  18. Restraining Na-Montmorillonite Delamination in Water by Adsorption of Sodium Dodecyl Sulfate or Octadecyl Trimethyl Ammonium Chloride on the Edges

    Directory of Open Access Journals (Sweden)

    Hongliang Li

    2016-08-01

    Full Text Available The delamination of montmorillonite in water leads to sliming in ore slurry, which is detrimental to mineral flotation and solid/water separation. In this work, the delamination of Na-montmorillonite (Na-MMT has been restrained by sodium dodecyl sulfate (SDS or octadecyl trimethyl ammonium chloride (1831 through the adsorption on the edge of the mineral. The experimental results have shown that the pretreatment by adding SDS and 1831 could greatly reduce the Stokes size percentage of −1.1 µm particles in the aqueous Na-MMT suspension. From the X-ray diffractometer (XRD results, the interlayer spacing of the MMT pre-treated by SDS and 1831 is smaller than that of original MMT particles. Adsorption position of SDS and 1831 on MMT surfaces was analyzed by the measurements of adsorption capacity of SDS and 1831, inductively-coupled plasma spectra, and zeta potential before and after the plane surface of MMT was covered with tetraethylenepentaminecopper ([Cu(tetren]2+. The results indicated that SDS and 1831 are adsorbed on the edge and the whole surface of Na-MMT, respectively. Delamination of MMT could be well restrained by the adsorption of SDS and 1831 on the edges of MMT.

  19. Electrochemical quartz crystal microbalance studies on enzymatic specific activity and direct electrochemistry of immobilized glucose oxidase in the presence of sodium dodecyl benzene sulfonate and multiwalled carbon nanotubes.

    Science.gov (United States)

    Su, Yuhua; Xie, Qingji; Chen, Chao; Zhang, Qingfang; Ma, Ming; Yao, Shouzhuo

    2008-01-01

    The electrochemical quartz crystal microbalance (EQCM) technique was utilized to monitor in situ the adsorption of glucose oxidase (GOD) and the mixture of GOD and sodium dodecyl benzene sulfonate (SDBS) onto Au electrodes with and without modification of multiwalled carbon nanotubes (MWCNTs) or SDBS/MWCNTs composite, and the relationship between enzymatic specific activity (ESA) and direct electrochemistry of the immobilized GOD was quantitatively evaluated for the first time. Compared with the bare gold electrode at which a little GOD was adsorbed and the direct electrochemistry of the adsorbed GOD was negligible, the amount and electroactivity of adsorbed GOD were greatly enhanced when the GOD was mixed with SDBS and then adsorbed onto the SDBS/MWCNTs modified Au electrode. However, the ESA of the adsorbed GOD was fiercely decreased to only 16.1% of the value obtained on the bare gold electrode, and the portion of adsorbed GOD showing electrochemical activity exhibited very low enzymatic activity, demonstrating that the electroactivity and ESA of immobilized GOD responded oppositely to the presence of MWCNTs and SDBS. The ESA results obtained from the EQCM method were well supported by conventional UV-vis spectrophotometry. The direct electrochemistry of redox proteins including enzymes as a function of their biological activities is an important concern in biotechnology, and this work may have presented a new and useful protocol to quantitatively evaluate both the electroactivity and ESA of trace immobilized enzymes, which is expected to find wider applications in biocatalysis and biosensing fields.

  20. Synergistic effect of sodium dodecyl sulfate and cetyltrimethyl ammonium bromide on the corrosion inhibition behavior of l-methionine on mild steel in acidic medium

    Directory of Open Access Journals (Sweden)

    M. Mobin

    2017-02-01

    Full Text Available The corrosion inhibition behavior of amino acid l-methionine (LMT separately and in combination with very low concentration of surfactants sodium dodecyl sulfate (SDS and cetyltrimethyl ammonium bromide (CTAB on mild steel in 0.1 M H2SO4 solution was studied, using weight loss and potentiodynamic polarization measurement techniques. The studies were carried out in the temperature range of 30–60 °C. The surface morphology of the corroded steel samples was studied by scanning electron microscopy (SEM and atomic force microscopy (AFM.The results show that LMT is an effective inhibitor for mild steel corrosion in 0.1 M H2SO4 which is synergistically improved in the presence of SDS and CTAB. The mixed LMT and CTAB is more effective as an inhibitor than mixture of LMT and SDS. The SEM and AFM photographs show a clearly different surface morphology in the presence of additives. LMT alone and in combination with surfactants obeys Langmuir adsorption isotherm from the fit of the experimental data of all concentrations and temperatures studied. Phenomenon of physical adsorption is proposed from the trend of the IE with temperature and also the values of activation energy (Ea, standard enthalpy of adsorption (ΔHads, and standard free energy of adsorption (ΔGads obtained. The results obtained by potentiodynamic polarization measurements are consistent with the results of the weight loss measurements. LMT acts as a mixed type inhibitor.

  1. Effect of sodium dodecyl sulfate (SDS) on stress response in the Mediterranean mussel (Mytilus Galloprovincialis): regulatory volume decrease (Rvd) and modulation of biochemical markers related to oxidative stress.

    Science.gov (United States)

    Messina, Concetta Maria; Faggio, Caterina; Laudicella, Vincenzo Alessandro; Sanfilippo, Marilena; Trischitta, Francesca; Santulli, Andrea

    2014-12-01

    In this study the effects of an anionic surfactant, sodium dodecyl sulfate (SDS), are assessed on the Mediterranean mussel (Mytilus galloprovincialis), exposed for 18 days at a concentration ranging from 0.1 mg/l to 1 mg/l. The effects are monitored using biomarkers related to stress response, such as regulatory volume decrease (RVD), and to oxidative stress, such as reactive oxygen species (ROS), endogenous antioxidant systems and Hsp70 levels. The results demonstrate that cells from the digestive gland of M. galloprovincialis, exposed to SDS were not able to perform the RVD owing to osmotic stress. Further, SDS causes oxidative stress in treated organisms, as demonstrated by the increased ROS production, in comparison to the controls (p<0.05). Consequently, two enzymes involved in ROS scavenging, superoxide dismutase (SOD) and catalase (CAT) have higher activities and the proportion of oxidized glutathione (GSSG) is higher in hepatopancreas and mantle of treated animals, compared to untreated animals (p<0.05). Furthermore Hsp70 demonstrates an up-regulation in all the analyzed tissues of exposed animals, attesting the stress status induced by the surfactant with respect to the unexposed animals. The results highlight that SDS, under the tested concentrations, exerts a toxic effect in mussels in which the disruption of the osmotic balance follows the induction of oxidative stress.

  2. Self-aggregation of synthesized novel bolaforms and their mixtures with sodium dodecyl sulfate (SDS) and cetyltrimethylammonium bromide (CTAB) in aqueous medium.

    Science.gov (United States)

    Maiti, Kajari; Mitra, Debolina; Mitra, Rajendra N; Panda, Amiya K; Das, Prasanta K; Rakshit, Animesh K; Moulik, Satya P

    2010-06-10

    Bolaforms B(1), B(2), and B(3) of the formulas, Br(-)Me(3)N(+)(CH(2))(10)N(+)Me(3)Br(-), Br(-)Me(3)N(+)(CH(2))(10)OH, and Br(-)Me(3)N(+)(CH(2))(10)COO(-)Na(+), respectively, were synthesized, and their properties in the bulk as well as at the air/aqueous NaBr (10 mM) solution interface have been studied. Their interactions with sodium dodecyl sulfate (SDS) and cetyltrimethylammonium bromide (CTAB) also have been investigated. Tensiometry, conductometry, spectrophotometry, and microcalorimetry techniques were used for characterization and estimation. Both pure bolaforms and their mixtures with SDS and CTAB have been found to self-aggregate, forming micelles in solution. The mixed systems of bolaform and SDS have been observed to form both micelles and vesicles. Their mutual interactions were synergistic, which at the interface was more spontaneous than in the bulk. The interfacial and bulk compositions of the mixed binary systems (bolaform and SDS or CTAB) with their associated interaction parameters have been estimated from the Rosen interaction model and the regular solution theory of Rubingh, respectively. The formed vesicles have been found to entrap the water-soluble dye, bromophenol blue, and the dye solubilized vesicles of B(1)-SDS and B(2)-SDS completely eluted out of the sephadex column proving their formation. A rough estimation of the size and polydispersity index of the formed micelles and vesicles has been made from DLS measurements.

  3. Sodium dodecyl sulfate-ethoxylated polyethylenimine adsorption at the air-water interface: how the nature of ethoxylation affects the pattern of adsorption.

    Science.gov (United States)

    Batchelor, Stephen N; Tucker, Ian; Petkov, Jordan T; Penfold, Jeffrey; Thomas, Robert K

    2014-08-19

    The strong interaction between ionic surfactants and polyelectrolytes of opposite charge results in enhanced surface adsorption at the air-water interface down to low surfactant concentrations and in some cases in the formation of ordered surface structures. A notable example which exhibits such properties is the mixture of polyethylenimine, PEI, and sodium dodecyl sulfate, SDS. However, the electrostatic interaction, around charge neutralization, between the surfactant and polymer often results in precipitation or coacervation. This can be mitigated for PEI-surfactant mixtures by ethoxylation of the PEI, but this can also result in a weaker surface interaction and a significant reduction in the adsorption. It is shown here that by localizing the ethoxylation of the PEI into discrete regions of the polymer precipitation upon the addition of SDS is suppressed, the strong surface interaction and enhanced adsorption of the polymer-surfactant mixture is retained. The adsorption of SDS in the presence of ethoxylated PEI is greatly enhanced at low SDS concentrations compared to the adsorption for pure SDS. The adsorption is equally pronounced at pH 7 and 10 and is largely independent of the degree of ethoxylation. Surface ordering, more than monolayer adsorption, is observed over a relatively narrow range of SDS concentrations and is most pronounced at pH 10 and for the polymers with the lower degree of ethoxylation. The results show that ethoxylated PEI's reported here provide a suitable route to enhanced surfactant adsorption while retaining favorable solution properties in which precipitation effects are minimized.

  4. An Investigation of Structure Transition in Sodium Dodecyl Trioxyethylene Sulfate/n-Butanol/n-Octane/Water System by Dielectric Relaxation Spectroscopy Method

    Institute of Scientific and Technical Information of China (English)

    MU Jian-hai; ZHAO Kong-shuang; WEI Su-xiang; LI Ying; LI Gan-zuo

    2004-01-01

    The phase diagram of the quaternary system of sodium dodecyl trioxyethylene sulfate(SDES)/n-butanol/n-octane/water was obtained at (30.0±0.1) ℃. There exists a clear, isotropic, and low-viscosity L phase, which can be divided into W/O, bi-continuous(B.C.) and O/W microemulsions by conductivity measurement results. Dielectric Relaxation Spectroscopy(DRS) measurements, including permittivity, conductivity, relaxation strength, characteristic relaxation time, dielectric parameters, phase parameters, etc., were applied to investigating the microstructures of the system mentioned above. For the samples with a fixed SDES/n-butanol mass ratio of 4/6 including 20%(mass fraction) of n-octane, DRS indicated a structure transition from a W/O to an O/W via a B.C. microemulsion with the increase of the water content. For the samples with a fixed (SDES/20%n-octane)/H2O mass ratio of 5/5, DRS presented that there only exists a onefold structure of a W/O microemulsion as the (n-butanol/20%n-octane) content increases. The results obtained from DRS are in good agreement with those from the phase diagram.

  5. Thermodynamic characteristics of the dissolution of glycine, glycylglycine, and glycylglycylglycine in aqueous solutions of sodium dodecyl sulfate at T = 298.15 K

    Science.gov (United States)

    Smirnov, V. I.; Badelin, V. G.

    2017-09-01

    the enthalpies of dissolution of glycine (Gly), glycylglycine (GlyGly), and glycylglycylglycine (GlyGlyGly) are measured in aqueous solutions of sodium dodecyl sulfate (SDS) at SDS concentrations m = 0-0.7 mol kg-1 and T = 298.15 K by means of calorimetry. The obtained data are used to calculate the standard values of enthalpies of dissolution (Δsol H m ) and enthalpies of transfer (Δtr H m ) of glycine and its oligomers from water to SDS aqueous solutions. The dependences of Δsol H m and Δtr H m on SDS concentration in an aqueous solution at a constant concentration of glycine and its oligomers are determined. A comparative analysis of the thermodynamic characteristics of Gly, GlyGly, and GlyGlyGly transfer within the studied range of SDS concentrations is performed. The results are interpreted in terms of ion-ion, ion-polar, and hydrophobic interactions between SDS and molecules of glycine and its oligomers.

  6. Petal-shaped poly(3,4-ethylenedioxythiophene)/sodium dodecyl sulfate-graphene oxide intercalation composites for high-performance electrochemical energy storage

    Science.gov (United States)

    Zhou, Haihan; Han, Gaoyi; Fu, Dongying; Chang, Yunzhen; Xiao, Yaoming; Zhai, Hua-Jin

    2014-12-01

    A facile and one-step electrochemical codeposition method is introduced for incorporating graphene oxide (GO) into poly(3,4-ethylenedioxythiophene) (PEDOT) films in the presence of sodium dodecyl sulfate (SDS). The as-prepared PEDOT/SDS-GO composites are characterized using scanning electron microscope, transmission electron microscopy, Fourier transform infrared spectroscopy, and X-ray diffraction. The results show that PEDOT/SDS-GO composites possessing a unique petal-shaped morphology have been prepared successfully and exhibit an intercalated microstructure. With the purpose of electrochemical energy storage, the properties of electrochemical capacitance for composites have also been investigated with cyclic voltammetry, galvanostatic charge/discharge measurements, and electrochemical impedance spectroscopy tests. The electrochemical test results manifest the PEDOT/SDS-GO composites have superior capacitive behaviors and cyclic stability, and a high areal capacitance of 79.6 mF cm-2 is achieved at 10 mV s-1 cyclic voltammetry scan. Furthermore, the PEDOT/SDS-GO composites exhibit more superior capacitive performance than that of PEDOT/SDS, indicating the incorporation of GO into the composites effectively boosts the capacitive performance of PEDOT-based supercapacitor electrodes. We consider that this research further extends the application of GO and the composites prepared can be developed as the candidate for the fabrication of low-cost, high-performance supercapacitors for energy storage.

  7. How Chain Length and Charge Affect Surfactant Denaturation of Acyl Coenzyme A Binding Protein (ACBP)

    DEFF Research Database (Denmark)

    Andersen, Kell Kleiner; Otzen, Daniel

    2009-01-01

    Using intrinsic tryptophan fluorescence, equilibria and kinetics of unfolding of acyl coenzyme A binding protein (ACBP) have been investigated in sodium alkyl sulfate surfactants of different chain length (8-16 carbon atoms) and with different proportions of the nonionic surfactant dodecyl...... maltoside (DDM). The aim has been to determine how surfactant chain length and micellar charge affect the denaturation mechanism. ACBP denatures in two steps irrespective of surfactant chain length, but with increasing chain length, the potency of the denaturant rises more rapidly than the critical micelle...... constants increases linearly with denaturant concentration below the cmc but declines at higher concentrations. Both shortening chain length and decreasing micellar charge reduce the overall kinetics of unfolding and makes the dependence of unfolding rate constants on surfactant concentration more complex...

  8. The degradation of sodium dodecyl sulfate based on graphene-modified MFC%石墨烯修饰微生物燃料电池降解十二烷基磺酸钠

    Institute of Scientific and Technical Information of China (English)

    姜倩利; 杨胜科; 张倩; 周扬

    2016-01-01

    以十二烷基磺酸钠为阳极电子供体,同时以石墨烯为催化剂对电极进行修饰。将修饰前后微生物燃料电池的产电性能和十二烷基磺酸钠的降解情况进行对比,经过修饰的电极装置产电效率明显增大,最大电压增加了1倍,并使十二烷基磺酸钠的降解率从49.85%提高到65.11%。这说明用石墨烯修饰后的微生物燃料电池在稳定产电的同时降解十二烷基磺酸钠是可行的,为废水中阴离子表面活性剂的去除提供了新的方法与研究方向。%With sodium dodecyl sulfate as anode electron donor and graphene as catalyst to modify the electrodes,the production performance of MFC and the degradation rate of sodium dodecyl sulfate are compared before and after modification.The treatment effect of modified MFC is two times as the unmodi-fied and the degradation of sodium dodecyl sulfate rate can reach 65 .1 1% from 49 .85%.The perform-ance of MFC with graphene modify electrode and the rate of degradation of SDS was tested.It indicates a good effect with graphene modified MFC to degrade sodium dodecyl sulfate and provides a new orientation for removal of the kind of anionic surfactant in organic wastewater treatment.

  9. Biopartitioning micellar chromatography with sodium dodecyl sulfate as a pseudo α(1)-acid glycoprotein to the prediction of protein-drug binding.

    Science.gov (United States)

    Hadjmohammadi, Mohammadreza; Salary, Mina

    2013-01-01

    A simple and fast method is of urgent need to measure protein-drug binding affinity in order to meet the rapid development of new drugs. Biopartitioning micellar chromatography (BMC), a mode of micellar liquid chromatography (MLC) using micellar mobile phases in adequate experimental conditions, can be useful as an in vitro system in mimicking the drug-protein interactions. In this study, sodium dodecyl sulfate-micellar liquid chromatography (SDS-MLC) was used for the prediction of protein-drug binding based on the similar property of SDS micelles to α(1)-acid glycoprotein (AGP). The relationships between the BMC retention data of a heterogeneous set of 14 basic and neutral drugs and their plasma protein binding parameter were studied and the predictive ability of models was evaluated. Modeling of logk(BMC) of these compounds was established by multiple linear regression (MLR) and second-order polynomial models obtained in two different concentrations (0.07 and 0.09M) of SDS. The developed MLR models were characterized by both the descriptive and predictive ability (R(2)=0.882, R(CV)(2)=0.832 and R(2)=0.840, R(CV)(2)=0.765 for 0.07 and 0.09M SDS, respectively). The p values <0.01 also indicated that the relationships between the protein-drug binding and the logk(BMC) values were statistically significant at the 99% confidence level. The standard error of estimation showed the standard deviation of the regression to be 11.89 and 13.87 for 0.07 and 0.09M, respectively. The application of the developed model to a prediction set demonstrated that the model was also reliable with good predictive accuracy. The external and internal validation results showed that the predicted values were in good agreement with the experimental value.

  10. Effect of β-Cyclodextrin Upon the Sol-gel Transition of Methylcellulose Solutions in the Presence of Sodium Dodecyl Sulfate

    Institute of Scientific and Technical Information of China (English)

    Hua-yu Li; Xiang Hao; Yong-jun Xie; Hai-yang Yang; He Liu; Jian-hui Luo

    2012-01-01

    The sol-gel transition temperature of methylcellulose (MC) solution in the presence of sodium dodecyl sulfate (SDS) as well as the mixtures of SDS andβ-cyclodextrin (β-CD) was measured,and the effect of the two competing interactions,the hydrophobic interaction between SDS and MC and the inclusion interaction between SDS and β-CD,upon the sol-gel transition of MC solution was studied.It has been found that the inclusion interaction between SDS and β-CD is much greater than the hydrophobic interaction between SDS and MC.As a result,in the coexistence of SDS and β-CD,the sol-gel transition temperature of MC solution keeps the same value,independent of the concentration of SDS in solution on condition that the concentration of SDS is less than β-CD.Our experimental results not only suggest that the effect of SDS upon the sol-gel transition of MC solution can be screened by β-CD completely but also indicate the inclusion ratio of SDS to β-CD can be determined quantitatively by using rheological measurement.The inclusion ratio of SDS toβ-CD is 1:1,which is in good agreement with the inclusion ratio of SDS to β-CD in the presence of poly(vincyl pyrrolidone) determined by the viscosity measurement but is critically different from the inclusion ratio of SDS toβ-CD in the presence of the oppositely charged polyelectrolyte by using the rheological measurement,mainly due to the reason that the mechanism of the interaction between SDS and MC is critically different from the mechanism of the interaction between SDS and the oppositely charged polyelectrolyte.

  11. Effects of aggregates on mixed adsorption layers of poly(ethylene imine) and sodium dodecyl sulfate at the air/liquid interface.

    Science.gov (United States)

    Tonigold, Katrin; Varga, Imre; Nylander, Tommy; Campbell, Richard A

    2009-04-07

    We have exploited the spatial and kinetic resolution of ellipsometry to monitor the lateral movement of inhomogeneous patches of material in mixed adsorption layers of poly(ethylene imine) and sodium dodecyl sulfate at the air/liquid interface. We show that the choice of sample preparation methods can have a profound effect on the state of the interface for chemically equivalent samples. The extent of aggregation in the bulk solution on relevant time scales is affected by specific details of the polymer/surfactant mixing process, which produces varying numbers of aggregates that can become trapped in the interfacial layer, resulting in an enhanced and fluctuating ellipsometry signal. It can be beneficial to apply the surface-cleaning method of aspiration prior to physical measurements to remove trapped aggregates through the creation of a fresh interface. At low pH, the ellipsometry signal of samples prepared with surface cleaning is remarkably constant over a factor of >500 in the bulk composition below charge equivalence, which is discussed in terms of possible adsorption mechanisms. At high pH, through observing temporal fluctuations in the ellipsometry signal of samples prepared with surface cleaning, we reveal two important processes: there is the spontaneous adsorption of aggregates > 0.2 microm in diameter into the interfacial layer, and with time there is the fusion of smaller aggregates to generate new large surface aggregates. We attribute the favorability of the adsorption and fusion processes at high pH to reduced electrostatic barriers resulting from the low surface charge density of the aggregates. It is inappropriate in this case to consider the interface to comprise a homogeneous adsorption layer that is in dynamic equilibrium with the bulk solution. Our work shows that it can be helpful to consider whether there are macroscopic particles embedded in molecular layers at the air/liquid interface for systems where there is prior knowledge of

  12. Direct speciation analysis of thallium based on solid phase extraction and specific retention of a Tl(III) complex on alumina coated with sodium dodecyl sulfate.

    Science.gov (United States)

    Biaduń, Ewa; Sadowska, Monika; Ospina-Alvarez, Natalia; Krasnodębska-Ostręga, Beata

    Alumina (Al2O3) with an average particle size of 63 μm was modified with the anionic surfactant sodium dodecyl sulfate (SDS) and then applied to (i) solid phase extraction and separation of both thallium(I) and thallium(III), and (ii) preconcentration of Tl(III) from waste water samples. Only Tl(III), in the form of its complex with diethylenetriaminepentaacetate (DTPA), was retained on the sorbent, from where it can be eluted with 40 % nitric acid. Thallium species were then quantified by ICP MS. The method was characterized by a LOD of 25 pg of Tl(I) and 160 pg of Tl(III) in 10 mL samples. A large excesses of Tl(I) over Tl(III) was tolerated, and relatively high levels of other metal ions, such as a 500-fold excess of Pb(II) and Cd(II), and a 2000-fold excess of Zn(II), respectively, do not interfere. The sorbent was easily prepared and possesses a high loading capacity, and these properties make it an attractive material for rapid and efficient extraction and speciation of Tl. Graphical abstract:Schematic of the SPE procedure for separation (with preconcentration) of Tl(III) from Tl(I) was developed and applied to direct speciation analysis of thallium in wastewater. Self-made columns packed with alumina coated with SDS were used. The method is resistant to interferences from Pb, Cd, Zn and tolerates a large excess of Tl(I) over Tl(III).

  13. Effect of light on self-assembly of aqueous mixtures of sodium dodecyl sulfate and a cationic, bolaform surfactant containing azobenzene.

    Science.gov (United States)

    Hubbard, F Pierce; Abbott, Nicholas L

    2007-04-24

    We report light and small-angle neutron scattering measurements that characterize microstructures formed in aqueous surfactant solutions (up to 1.0 wt % surfactant) containing mixtures of sodium dodecyl sulfate (SDS) and the light-sensitive bolaform surfactant, bis(trimethylammoniumhexyloxy)azobenzene dibromide (BTHA) as a function of composition, equilibration time, and photostationary state (i.e., solutions rich in cis-BTHA or trans-BTHA). We observed formation of vesicles in both SDS-rich and trans-BTHA-rich regions of the microstructure diagram, with vesicles present over a particularly broad range of compositions for trans-BTHA-rich solutions. Illumination of mixtures of BTHA and SDS with a broadband UV light source leads to formation of photostationary states where the fraction of BTHA present as cis isomer (75-80% cis-BTHA) is largely independent of the mixing ratio of SDS and BTHA. For a relatively limited set of mixing ratios of SDS and BTHA, we observed UV illumination of SDS-rich vesicles to result in the reversible transformation of the vesicles to micellar aggregates and UV illumination of BTHA-rich vesicles to result in irreversible precipitation. Surprisingly, however, for many mixtures of trans-BTHA and SDS that formed solutions containing vesicles, illumination with UV light (which was confirmed to lead to photoisomerization of BTHA) resulted in only a small decrease in the number of vesicles in solution, relatively little change in the sizes of the remaining vesicles, and coexistance of the vesicles with micelles. These observations are consistent with a physical model in which the trans and cis isomers of BTHA present at the photostationary state tend to segregate between the different microstructures coexisting in solution (e.g., vesicles rich in trans-BTHA and SDS coexist with micelles rich in cis-BTHA and SDS). The results presented in this paper provide guidance for the design of light-tunable surfactants systems.

  14. Stability of collagen during denaturation.

    Science.gov (United States)

    Penkova, R; Goshev, I; Gorinstein, S; Nedkov, P

    1999-05-01

    The stability of calf skin collagen (CSC) type I during thermal and chemical denaturation in the presence of glycerol was investigated. Thermal denaturation of type I collagen was performed in the presence of glycerol or in combination with urea and sodium chloride. The denaturation curves obtained in the presence of urea or sodium chloride retained their original shape without glycerol. These curves were shifted upward proportionally to the glycerol concentration in the reaction medium. This means that glycerol and the denaturants act independently. The explanation is based on the difference in the mechanism of their action on the collagen molecule.

  15. Identification of Contaminations Hiding Beneath the α- and β-Subunits of Partially Purified Nitrogenase MoFe Protein on the Sodium Dodecyl Sulfate Gel

    Institute of Scientific and Technical Information of China (English)

    Hui-Na ZHOU; Ying ZHAO; Shao-Min BIAN; Jian-Feng ZHAO; Fei REN; Huang-Ping WANG; Ju-Fu HUANG

    2005-01-01

    To identify the unknown proteins that would contaminate the α- and β-subunits of nitrogenase MoFe protein on sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), the partially purified MoFe protein (Av 1) preparation was obtained from Azotobacter vinelandii Lipmann OP by chromatography on DEAE-cellulose (DE52) and Sephacryl S-200 columns and analyzed by PAGE and matrixassisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry. The Av 1 preparation was shown to have two main bands at the position of the α- and β-subunits of crystalline Avl on the SDS gel. However, on the anoxic native PAGE, in addition to the Ay 1 band, the preparation was shown to have three other main bands that migrated slower than Avl. Of these three main bands, the protein with the fastest migration was identified as bacterioferritin elsewhere. The proteins on the other two bands, termed Upper and Middle, were suggested to be two different homopolymers with the same apparent subunit electrophoretic mobilities as the α- and β-subunits of Avl, respectively. By analysis of MALDI-TOF mass spectrometry, the Upper was identified as GroEL, which belongs to the heat shock protein 60 family, and the Middle was identified as glucose-6-phosphate isomerase (PGI). In our preparation, anoxic native electrophoresis indicated that GroEL was composed of 14 identical subunits and that PGI was composed of 10 identical subunits. This is the first report of PGI, with so many subunits. The contaminating proteins in the Av 1 preparation, mainly GroEL and PGI, could be totally or partially removed from Av1 if the shoulders and center of the elution peak were collected separately from the Sephacryl S-200 column and the center fraction was purified further by Q-Sepharose developed with an NaCl concentration gradient. Thus, Avl with more than 90% purity was obtained. Obviously, this modified method is useful for the purification of mutant MoFe proteins with a high purity.

  16. Giant extracellular Glossoscolex paulistus Hemoglobin (HbGp) upon interaction with cethyltrimethylammonium chloride (CTAC) and sodium dodecyl sulphate (SDS) surfactants: Dissociation of oligomeric structure and autoxidation.

    Science.gov (United States)

    Santiago, Patricia S; Moreira, Leonardo M; de Almeida, Erika V; Tabak, Marcel

    2007-04-01

    The effects of two ionic surfactants on the oligomeric structure of the giant extracellular hemoglobin of Glossoscolex paulistus (HbGp) in the oxy - form have been studied through the use of several spectroscopic techniques such as electronic optical absorption, fluorescence emission, light scattering, and circular dichroism. The use of anionic sodium dodecyl sulphate (SDS) and cationic cethyltrimethyl ammonium chloride (CTAC) has allowed to differentiate the effects of opposite headgroup charges on the oligomeric structure dissociation and hemoglobin autoxidation. At pH 7.0, both surfactants induce the protein dissociation and a significant oxidation. Spectral changes occur at very low CTAC concentrations suggesting a significant electrostatic contribution to the protein-surfactant interaction. At low protein concentration, 0.08 mg/ml, some light scattering within a narrow CTAC concentration range occurs due to protein-surfactant precipitation. Light scattering experiments showed the dissociation of the oligomeric structure by SDS and CTAC, and the effect of precipitation induced by CTAC. At higher protein concentrations, 3.0 mg/ml, a precipitation was observed due to the intense charge neutralization upon formation of ion pair in the protein-surfactant precipitate. The spectral changes are spread over a much wider SDS concentration range, implying a smaller electrostatic contribution to the protein-surfactant interactions. The observed effects are consistent with the acid isoelectric point (pI) of this class of hemoglobins, which favors the intense interaction of HbGp with the cationic surfactant due to the existence of excess acid anionic residues at the protein surface. Protein secondary structure changes are significant for CTAC at low concentrations while they occur at significantly higher concentrations for SDS. In summary, the cationic surfactant seems to interact more strongly with the protein producing more dramatic spectral changes as compared to the

  17. Rapid discrimination of Gram-positive and Gram-negative bacteria in liquid samples by using NaOH-sodium dodecyl sulfate solution and flow cytometry.

    Directory of Open Access Journals (Sweden)

    Atsushi Wada

    Full Text Available BACKGROUND: For precise diagnosis of urinary tract infections (UTI, and selection of the appropriate prescriptions for their treatment, we explored a simple and rapid method of discriminating gram-positive and gram-negative bacteria in liquid samples. METHODOLOGY/PRINCIPAL FINDINGS: We employed the NaOH-sodium dodecyl sulfate (SDS solution conventionally used for plasmid extraction from Escherichia coli and the automated urine particle analyzer UF-1000i (Sysmex Corporation for our novel method. The NaOH-SDS solution was used to determine differences in the cell wall structures between gram-positive and gram-negative bacteria, since the tolerance to such chemicals reflects the thickness and structural differences of bacterial cell walls. The UF-1000i instrument was used as a quantitative bacterial counter. We found that gram-negative bacteria, including E. coli, in liquid culture could easily be lysed by direct addition of equal volumes of NaOH-SDS solution. In contrast, Enterococcus faecalis, which is a gram-positive bacterium, could not be completely lysed by the solution. We then optimized the reaction time of the NaOH-SDS treatment at room temperature by using 3 gram-positive and 4 gram-negative bacterial strains and determined that the optimum reaction time was 5 min. Finally, in order to evaluate the generalizability of this method, we treated 8 gram-positive strains and 8 gram-negative strains, or 4 gram-positive and 4 gram-negative strains incubated in voluntary urine from healthy volunteers in the same way and demonstrated that all the gram-positive bacteria were discriminated quantitatively from gram negative bacteria using this method. CONCLUSIONS/SIGNIFICANCE: Using our new method, we could easily discriminate gram-positive and gram-negative bacteria in liquid culture media within 10 min. This simple and rapid method may be useful for determining the treatment course of patients with UTIs, especially for those without a prior history

  18. Implementation of USP antibody standard for system suitability in capillary electrophoresis sodium dodecyl sulfate (CE-SDS) for release and stability methods.

    Science.gov (United States)

    Esterman, Abbie L; Katiyar, Amit; Krishnamurthy, Girija

    2016-09-05

    Capillary electrophoresis sodium dodecyl sulfate (CE-SDS) is widely used for purity analysis of monoclonal antibody therapeutics for release and stability to demonstrate product consistency and shelf life during the manufacturing and life cycle of the product. CE-SDS method development is focused on exploring the method capability to provide the information about the product purity and product related degradants (fragmentation, aggregation etc.). In order to establish the functionality of the instrumentation, software, and sample preparation; system suitability criteria need to be defined for analytical methods using a well characterized reference standard run under the same protocol and analysis as the test articles. Typically the reference standard is produced using a manufacturing process representative of the clinical material. The qualification, control, and maintenance of in-house reference standards are established through rigorous quality and regulatory guidelines. The U.S. Pharmacopeia (USP) has developed a monoclonal IgG System Suitability Reference Standard to be utilized for assessment of system suitability in CE-SDS methods. In this communication, we evaluate the system suitability acceptance criteria performance of the USP IgG standard using two methods, the recommended USP protocol provided in monograph and a molecule specific Bristol-Myers Squibb (BMS) CE-SDS method. The results from USP IgG standard were compared with two in-house monoclonal antibody reference standards. The data suggest that the USP CE-SDS method may not be suitable for CE-SDS analysis for release and stability of monoclonal antibody therapeutics due to the high level of method induced partial reduction observed for all molecules tested. This high level of fragmentation observed utilizing the USP method will result in reporting lower purity levels, which will impact the overall quality assessment of the molecule. The system suitability criteria recommended by the USP method can be

  19. Luminescence and bio-imaging response of thio-glycolic acid (TGA) and sodium dodecyl sulfate (SDS)-coated fluorescent cadmium selenide quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Sarma, Runjun; Mohanta, Dambarudhar, E-mail: best@tezu.ernet.in

    2015-05-15

    We demonstrate the usefulness of surfactant coated CdSe quantum dots in bio-imaging applications after evaluating their steady state and time resolved emission responses. The surfactant coated QDs, with the respective sizes of ~14 nm and 10 nm are synthesized considering two different types of coating agents, namely, thio-glycolic acid (TGA) and sodium dodecyl sulfate (SDS). The steady state luminescence response is characterized by both near band edge (NBE) and defect-related emissions, but with a strong dependency on the nature of surfactant coating. Time resolved photoluminescence (TR-PL) studies have revealed bi-exponential characteristics with CdSe–TGA QDs exhibiting longer life time decay parameters than those of CdSe–SDS QDs. To be specific, the fast (τ{sub 1}) and the slow (τ{sub 2}) components are characterized by ~10 and 30 times larger values in the former than the latter case. In the FT-IR spectra, several stretching and bending vibrations are observed to be adequately influenced by the nature of surfactant coating. The availability of plentiful Na{sup +} counter ions around SDS coated QDs, as evident from the FT-IR spectroscopy studies, can also be responsible for obtaining reduced size of the QDs. In contrast, Raman active modes are apparently distinguishable in TGA coated QDs, with LO and TO mode positions significantly blue-shifted from the bulk values. While attributing to the intense defect mediated emission of TGA coated QDs, the effect of TGA coating presented a stronger fluorescence imaging capability over the SDS coated ones. A detailed assessment of fluorescent counts, as a basis of bio-imaging response, is being discussed on a comparative basis. - Highlights: • Fluorescent CdSe quantum dots are synthesized with two different kinds of surfactant coatings. • Time resolved photoluminescence (TR-PL) studies have revealed bi-exponential decay characteristics. • Both slow and fast decay parameters are found to be longer in CdSe QDs

  20. 十二烷基磺酸钠/异辛烷/正构醇/水微乳状液的相行为及其结构转变的研究%Phase Behavior and Structural Transitions in Sodium Dodecyl Sulfonate Microemulsions

    Institute of Scientific and Technical Information of China (English)

    杨根生; 施介华; 李景华; 王普; 姚善泾

    2002-01-01

    The forming mechanism ofmicroemulsion of sodium dodecyl sulfonate, alcohols, water and isooctane was studied, with particular emphasis on the effect of molecular weight and concentration of alcohols. Phase diagram of the four components, alcohol,sodium dodecyl sulfonate, water and isooctane, was used as a means of study, through which the microemulsion regions were determined. Phase diagram of sodium dodecyl sulfonate/n-pentanol/isooctane/water system at km, = 2 (km, = Wn-pentanol / WsDs ) is presented.The variation of conductivities of different microemulsion samples with water was measured. From the conductivities we investigated a change in structure from water droplets in oil (W/O) at low water content to liquid crystal at intermediate water content and a struc ture ofoil droplets in water (O/W) at high water content.

  1. [Denaturalized psychoanalysts].

    Science.gov (United States)

    Peglau, Andreas

    2011-01-01

    This paper presents hitherto unknown material from the German Foreign Office referring to the denaturalization of Therese Benedek, Bruno Bettelheim, Adolf Storfer and Wilhelm Reich by Nazi Germany. It corroborates the finding that nobody was persecuted by the Nazis solely on the basis of psychoanalytic activities or membership in a psychoanalytic organization.

  2. LINEAR SOLVATION ENERGY RELATIONSHIPS FOR CHARACTERIZATION OF MLC SYSTEMS WITH SODIUM DODECYL SULPHATE MOBILE PHASES MODIFIED BY ALIPHATIC ALCOHOLS OR CARBOXYLIC ACIDS

    NARCIS (Netherlands)

    Markov, Vadym V.; Boichenko, Alexander P.; Loginova, Lidia P.

    2012-01-01

    The Linear Solvation Energy Relationships (LSER) have been successfully used for the modeling of partition and retention of the set of test compounds in different systems. The properties of micellar chromatographic systems with the mobile phases on the basis of sodium dodecylsulphate modified (ODS)

  3. 光度法研究十二烷基硫酸钠的临界胶束浓度%Determination of critical micelle concentration of sodium dodecyl sulfate by using spectrophotometry

    Institute of Scientific and Technical Information of China (English)

    王新红; 戴兢陶; 顾云兰

    2011-01-01

    Critical micelle concentrations (CMC) of sodium dodecyl sulfate (SDS) in aqueous solution of io dine and I-3 solution were determined, and two salts, sodium sulfate and potassium chloride on the impact of CMC of SDS in the aqueous solution of iodine in different concentrations of iodine were also discussed.The CMC of SDS obtained in two different systems are different by using spectrophotometry. Sodium sul fate salts on the impact of the surface activity of SDS are greater than potassium chloride in I-3 solution, and with the increasing concentration of iodine, the CMC of SDS show the trend of increasing in the aqueous so lution of iodine.%在碘的水溶液和I-3溶液2种体系中测定了十二烷基硫酸钠(SDS)的临界胶束浓度(CMC),讨论了在I-3体系中,不同硫酸钠和氯化钾对测定结果的影响,在碘的水溶液中研究了不同碘浓度对SDS的CMC的影响.采用分光光度法求得SDS在两种体系中的CMC值,硫酸钠与氯化钾对CMC的值有影响,且硫酸钠对SDS的表面活性影响大于氯化钾;在碘的水溶液中,随碘的浓度增大,CMC呈增大趋势.

  4. Protecting role of cosolvents in protein denaturation by SDS: a structural study

    Directory of Open Access Journals (Sweden)

    Wouters Johan

    2008-06-01

    Full Text Available Abstract Background Recently, we reported a unique approach to preserve the activity of some proteins in the presence of the denaturing agent, Sodium Dodecyl Sulfate (SDS. This was made possible by addition of the amphipathic solvent 2,4-Methyl-2-PentaneDiol (MPD, used as protecting but also as refolding agent for these proteins. Although the persistence of the protein activity in the SDS/MPD mixture was clearly established, preservation of their structure was only speculative until now. Results In this paper, a detailed X-ray study addresses the pending question. Crystals of hen egg-white lysozyme were grown for the first time in the presence of MPD and denaturing concentrations of SDS. Depending on crystallization conditions, tetragonal crystals in complex with either SDS or MPD were collected. The conformation of both structures was very similar to the native lysozyme and the obtained complexes of SDS-lysozyme and MPD-lysozyme give some insights in the interplay of protein-SDS and protein-MPD interactions. Conclusion This study clearly established the preservation of the enzyme structure in a SDS/MPD mixture. It is hypothesized that high concentrations of MPD would change the properties of SDS and lower or avoid interactions between the denaturant and the protein. These structural data therefore support the hypothesis that MPD avoids disruption of the enzyme structure by SDS and can protect proteins from SDS denaturation.

  5. Mixed hemimicelles solid-phase extraction based on sodium dodecyl sulfate-coated nano-magnets for selective adsorption and enrichment of illegal cationic dyes in food matrices prior to high-performance liquid chromatography-diode array detection detection.

    Science.gov (United States)

    Qi, Ping; Liang, Zhi-an; Wang, Yu; Xiao, Jian; Liu, Jia; Zhou, Qing-qiong; Zheng, Chun-hao; Luo, Li-Ni; Lin, Zi-hao; Zhu, Fang; Zhang, Xue-wu

    2016-03-11

    In this study, mixed hemimicelles solid-phase extraction (MHSPE) based on sodium dodecyl sulfate (SDS) coated nano-magnets Fe3O4 was investigated as a novel method for the extraction and separation of four banned cationic dyes, Auramine O, Rhodamine B, Basic orange 21 and Basic orange 22, in condiments prior to HPLC detection. The main factors affecting the extraction of analysts, such as pH, surfactant and adsorbent concentrations and zeta potential were studied and optimized. Under optimized conditions, the proposed method was successful applied for the analysis of banned cationic dyes in food samples such as chili sauce, soybean paste and tomato sauce. Validation data showed the good recoveries in the range of 70.1-104.5%, with relative standard deviations less than 15%. The method limits of determination/quantification were in the range of 0.2-0.9 and 0.7-3μgkg(-1), respectively. The selective adsorption and enrichment of cationic dyes were achieved by the synergistic effects of hydrophobic interactions and electrostatic attraction between mixed hemimicelles and the cationic dyes, which also resulted in the removal of natural pigments interferences from sample extracts. When applied to real samples, RB was detected in several positive samples (chili powders) within the range from 0.042 to 0.177mgkg(-1). These results indicate that magnetic MHSPE is an efficient and selective sample preparation technique for the extraction of banned cationic dyes in a complex matrix.

  6. Identification and In Silico Analysis of Major Redox Modulated Proteins from Brassica juncea Seedlings Using 2D Redox SDS PAGE (2-Dimensional Diagonal Redox Sodium Dodecyl Sulfate Polyacrylamide Gel Electrophoresis).

    Science.gov (United States)

    Chaurasia, Satya Prakash; Deswal, Renu

    2017-02-01

    The thiol-disulphide exchange regulates the activity of proteins by redox modulation. Many studies to analyze reactive oxygen species (ROS), particularly, hydrogen peroxide (H2O2) induced changes in the gene expression have been reported, but efforts to detect H2O2 modified proteins are comparatively few. Two-dimensional diagonal redox sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS PAGE) was used to detect polypeptides which undergo thiol-disulphide exchange in Brassica juncea seedlings following H2O2 (10 mM) treatment for 30 min. Eleven redox responsive polypeptides were identified which included cruciferin, NLI [Nuclear LIM (Lin11, Isl-1 & Mec-3 domains)] interacting protein phosphatase, RuBisCO (ribulose-1,5-bisphosphate carboxylase/oxygenase) large subunit, and myrosinase. Redox modulation of RuBisCO large subunit was further confirmed by western blotting. However, the small subunit of RuBisCO was not affected by these redox changes. All redox modulated targets except NLI interacting protein (although it contains two cysteines) showed oxidation sensitive cysteines by in silico analysis. Interestingly, interactome of cruciferin and myrosinase indicated that they may have additional function(s) beside their well-known roles in the seedling development and abiotic stress respectively. Cruciferin showed interactions with stress associated proteins like defensing-like protein 192 and 2-cys peroxiredoxin. Similarly, myrosinase showed interactions with nitrilase and cytochrome p450 which are involved in nitrogen metabolism and/or hormone biosynthesis. This simple procedure can be used to detect major stress mediated redox changes in other plants.

  7. Surface atomic structures of Fe2O3 nanoparticles coated with cetyltrimethyl ammonium bromide and sodium dodecyl benzene sulphonate:an extended x-ray absorption fine-structure study

    Institute of Scientific and Technical Information of China (English)

    1999-01-01

    Fe2O3 nanoparticles coated with sodium dodecyl benzene sulphonate(DBS)or cetyltrimethyl ammonium bromide(CTAB) were prepared by using a microemulsion method in the system water/toluene.The nanoparticles were characterized by means of transmission electron microscopy and average particle sizes of 5.0nm and 6.0nm were found for DBS-modified and CTAB-modified nanoparticles respectively.The local atomic structures of these iron(Ⅲ) oxide nanoparticles were probed by using the extended x-ray absorption fine-structure technique.Fe K absorption spectra were collected at beam line 4W1B of Beijing Synchrotron Radiation Facility.A structureal model was proposed for describing their atomic structures.The Fe-O bond length at the surface of DBS-coated Fe2O3 nanoparticles was found to be similar to that in bulk Fe2O3.but there was about 0.04A expansion for the CTAB-coated Fe2O3 nanoparticles.On the basis of the model proposed in this paper,the thicknesses of the surface layers were estimated to be 0.5nm and 0.7nm.respectively,for the DBS-coated and CTAB-coated Fe2O3 nanoparticles.The anharmonicity of the atomic vibration and the asymmetry of atom-pair distribution were found to be larger at the surface of the nanoparticles than in the bulk material,while the Debye-Waller factors are almost the same for the surface and the core parts of the nanoparticles.It can be concluded that the atomic structure of the nanoparticle surface is ordered.but the atom-pari distribution is asymmetric.

  8. Molecular assessment of collagen denaturation in decellularized tissues using a collagen hybridizing peptide.

    Science.gov (United States)

    Hwang, Jeongmin; San, Boi Hoa; Turner, Neill J; White, Lisa J; Faulk, Denver M; Badylak, Stephen F; Li, Yang; Yu, S Michael

    2017-04-15

    Decellularized extracellular matrix (ECM) derived from tissues and organs are emerging as important scaffold materials for regenerative medicine. Many believe that preservation of the native ECM structure during decellularization is highly desirable. However, because effective techniques to assess the structural damage in ECM are lacking, the disruptive effects of a decellularization method and the impact of the associated structural damage upon the scaffold's regenerative capacity are often debated. Using a novel collagen hybridizing peptide (CHP) that specifically binds to unfolded collagen chains, we investigated the molecular denaturation of collagen in the ECM decellularized by four commonly used cell-removing detergents: sodium dodecyl sulfate (SDS), 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonate (CHAPS), sodium deoxycholate (SD), and Triton X-100. Staining of the detergent-treated porcine ligament and urinary bladder matrix with carboxyfluorescein-labeled CHP demonstrated that SDS and Triton X-100 denature the triple helical collagen molecule while CHAPS and SD do not, although second harmonic generation imaging and transmission electron microscopy (TEM) revealed that all four detergents disrupt collagen fibrils. Our findings from the CHP staining were further confirmed by the circular dichroism spectra of intact triple helical collagen molecules in CHAPS and SD solutions, and the TEM images of CHP-conjugated gold nanoparticles binding only to the SDS and Triton X-100 treated collagen fibrils. CHP is a powerful new tool for direct and reliable measurement of denatured collagen molecules in decellularized tissues. It is expected to have wide applications in the development and standardization of the tissue/organ decellularization technology. Preservation of the native ECM structure in decellularized tissues is highly desirable, since denaturation of ECM molecules (e.g., collagen) during decellularization can strongly influence the cellular response

  9. Studies of muscle proteins in embryonic myocardial cells of cardiac lethal mutant mexican axolotls (Ambystoma mexicanum) by use of heavy meromyosin binding and sodium dodecyl sulfate polyacrylamide gel electrophoresis

    Science.gov (United States)

    1976-01-01

    In the Mexican axolotl Ambystoma mexicanum recessive mutant gene c, by way of abnormal inductive processes from surrounding tissues, results in an absence of embryonic heart function. The lack of contractions in mutant heart cells apparently results from their inability to form normally organized myofibrils, even though a few actin-like (60-A) and myosin-like (150-A) filaments are present. Amorphous "proteinaceous" collections are often visible. In the present study, heavy meromyosin (HMM) treatment of mutant heart tissue greatly increases the number of thin filaments and decorates them in the usual fashion, confirming that they are actin. The amorphous collections disappear with the addition of HMM. In addition, an analysis of the constituent proteins of normal and mutant embryonic hearts and other tissues is made by sodium dodecyl sulfate (SDS) gel electrophoresis. These experiments are in full agreement with the morphological and HMM binding studies. The gels show distinct 42,000-dalton bands for both normal and mutant hearts, supporting the presence of normal actin. During early developmental stages (Harrison's stage 34) the cardiac tissues in normal and mutant siblings have indistinguishable banding patterns, but with increasing development several differences appear. Myosin heavy chain (200,000 daltons) increases substantially in normal hearts during development but very little in mutants. Even so the quantity of 200,000-dalton protein in mutant hearts is significantly more than in any of the nonmuscle tissues studied (i.e. gut, liver, brain). Unlike normal hearts, the mutant hearts lack a prominent 34,000-dalton band, indicating that if mutants contain muscle tropomyosin at all, it is present in drastically reduced amounts. Also, mutant hearts retain large amounts of yolk proteins at stages when the platelets have virtually disappeared from normal hearts. The morphologies and electrophoresis patterns of skeletal muscle from normal and mutant siblings are

  10. 荷电膜去除水中表面活性剂十二烷基苯磺酸钠研究%STUDY ON THE REMOVAL OF SURFACTANT SODIUM DODECYL BENZENE SULFONATE BY CHARGED MEMBRANE

    Institute of Scientific and Technical Information of China (English)

    张洁欣; 魏俊富; 张环

    2011-01-01

    采用自制等离子体改性聚砜荷电膜对表面活性剂十二烷基苯磺酸钠(SDBS)进行截留测试,通过改变溶液的初始SDBS质量浓度(40~400 mg· L-1)、操作压力(0.15~0.35 MPa),离子强度(NaCl质量浓度100~300 mg·L-1)以及pH(2~12)等影响因素,观察荷电膜对SDBS溶液的截留率以及通量的变化,分析作用机理.结果表明,静电斥力为主要作用力,同时伴有机械筛分作用.初始SDBS含量低时比高时截留效果好,SDBS初始质量浓度为40 mg· L-1时截留率可达85.68%;低离子强度时静电斥力发挥主要作用,截留率比高离子强度时高;压力越大,截留率越高;溶液pH接近中性时截留效果最好.%Surfactant sodium dodecyl benzene sulfonate solution was retained by the plasma modified polysulfone charged membrane. The rejection tests were at different factors including solution concentration, operating pressure (0.15~0.35 Mpa), ionic strength (concentration of NaCl 100~300 mg*L') and pH (2~12). The retention rate and flux of SDBS solution retained by charged membrane were observed. The mechanism of retention was analyzed. Experimental results revealed that electrostatic repulsion was the main force in the process. And size exclusion also existed. Solutions possessing low concentration showed better rejection effect than those having high concentration. When initial feed concentration was 40 mg'L', the retention rate could reach 85.68%. Electrostatic repulsion played an important role at low ionic strength. The retention rate at low ionic strength was higher than those at high ionic strength. The retention rate increased as the operating pressure presented high. And the rejection performed well when pH was close to neutral.

  11. Role of additives; sodium dodecyl sulphate and manganese chloride on morphology of Zn{sub 1−x}Mn{sub x}O nanoparticles and their photoluminescence properties

    Energy Technology Data Exchange (ETDEWEB)

    Pandey, Gajanan, E-mail: pandeygajanan@rediffmail.com [Department of Applied Chemistry, Babasaheb Bhimrao Ambedkar University, Lucknow 226025, U.P. (India); Dixit, Supriya; Shrivastava, A.K. [School of Studies in Physics, Jiwaji University, Gwalior 474011, M.P. (India)

    2014-10-15

    In the present study Zn{sub 1−x}Mn{sub x}O (x = 0, 0.05 and 0.1) nanoparticles (NPs) have been synthesised in aqueous solution phase at mild reaction temperature 100 °C in moderate alkaline medium (pH = 9.5), and the role of external additives; like sodium dodecyl sulphate and manganese chloride on the morphology and size of the products has been explored on the basis of transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD) and Fourier transform infrared spectral analyses data. ZnO hexagonal nano-plates, core–shell like spherical/ellipsoidal Zn{sub 0.95}Mn{sub 0.05}O structures and thin sheets, thorn/needle mixed shaped Zn{sub 0.9}Mn{sub 0.1}O structures have been observed in TEM and SEM images. Zn(OH){sub 2} formed in moderate alkaline medium, converted to Zn(II) hydroxo complex ions on dissolution, which further recrystallizes to produce wurtzite ZnO at 100 °C. From XRD and EDX analysis, successful doping of Mn{sup 2+} ions at the Zn{sup 2+} sites in ZnO host has been proved. In the photoluminescence spectra, the observed blue shifts in NBE peaks and decrease of emissions intensity on Mn doping have thoroughly been discussed in the present investigation. - Highlights: • Zn{sub 1−x}Mn{sub x}O NPs have been prepared in aqueous solution at mild temperature 100 °C. • Shifts in XRD lines and NBE peaks in PL spectra proved doping of Mn{sup 2+} in the ZnO. • ZnO is formed via dissolution–recrystallization of ε-Zn(OH){sub 2}–ZnO. • Additives SDS and MnCl{sub 2}·4H{sub 2}O play important role on morphology of Zn{sub 1−x}Mn{sub x}O NPs. • Mn contents increased extrinsic defects, which decreased intensity of PL spectra.

  12. 羊毛纤维吸附十二烷基磺酸钠的热力学研究%Thermodynamic study on the adsorption of sodium dodecyl sulfonate by wool fiber

    Institute of Scientific and Technical Information of China (English)

    戴丽; 耿信鹏; 林国栋

    2007-01-01

    采用电导法研究了366K(93℃)时经洁净处理的羊毛纤维在酸性(pH=3.0~3.5)水溶液中对十二烷基磺酸钠(SDS)的吸附等温线,以及羊毛在不同助剂(含乙二醇/苯甲醇和硫酸锌)的水溶液中对SDS的吸附等温线.结果表明,加入助剂后,SDS的吸附量均出现不同程度的下降.可解释为较高温度下,阴离子表面活性剂SDS在水中的溶解度升高.同时,苯甲醇、乙二醇分子中都含有羟基,亲水性较强,在水中的溶解度也较高,使得表面活性剂与水的亲和性增强,表面活性剂分子自水中逃离而吸附于羊毛上的趋势相对减少,故SDS的吸附量降低.由通用吸附等温线公式估算了不同助剂作用下SDS在羊毛/溶液界面吸附的表面胶团聚集数和表面胶团化标准自由能,与实验结果比较符合.本文还研究了在空白浴和加助剂("DL"、"FL")条件下分散染料上染羊毛的吸附等温线,并探讨了其吸附机理,从较深层次上探索其染色机理.%The adsorption isotherms of Sodium Dodecyl Sulfonate (SDS) onto wool fiber surface which experienced clean processing from an acid aqueous solution(pH3.0~3.5) by conductance method at 366K(93℃) were studied, so did the isotherms of wool adsorbing SDS from different aqueous solutions which containing various auxiliaries(containing glycol/benzalcohol and zinc sulfate). Some results can be found that all the adsorbed amounts of SDS show a descending trend at different degrees after adding the auxiliaries. The increasing solubility of the agent indicates the affinity of surfactant with water becoming stronger, and the trend of surfactant fleeing away water and adsorbed onto the wool is relatively decrease, which made the adsorbed amounts of SDS reduce. The surface micelle aggregation number and the standard Gibbs free energy for surface micellization of SDS adsorbed onto the wool/solution interface in the actions of different auxiliaries were estimated by the general

  13. 无机阴离子对TiO2-膨润土紫外光降解SDBS的影响%Effect of Inorganic Anion on Degradation of Sodium Dodecyl Benzene Sulfonate by TiO2-bentonite

    Institute of Scientific and Technical Information of China (English)

    温淑瑶; 马占青; 马敏立

    2012-01-01

    Photodegradation of sodium dodecyl benzene sulfonate (SDBS) by TiO2-bentonite is efficient, and the inorganic anions such as Cl-, SO42-, NO3-, HCO3-, H2PO4- which usually exist in water have an effect on photodegradation efficiency of SDBS by TiO2-bentonite. 36 mmol/L sodium salt of these inorganic anions was input into SDBS aqueous solution respectively,and the solutions were irradiated for 2 h with ultraviolet lamp. The difference of photodegradation results with or without the input of inorganic anions in the solution was compared. Results showed that effect of inorganic anion such as Cl-, SO42-, NO3-,HCO3-, H2PO4- on degradation of SDBS by TiO2-bentonite existed. Among which the effect of HCO3- on degradation was the most obvious, followed by H2PO-4 , NO3- , SO42-, Cl- The concentration of SDBS solutions with input of HCO3- , H2PO4- , NO3- ,SO42-, Cl- increased by 2.63, 1.63, 0.73, 0.52 and 0.46 times respectively within 2 h than that without input of the inorganic anions, which mainly depends on the competitions of surface active position between inorganic anions and organic molecules,appearance of high polarity environment near surface of catalyst particle and change of pH of solutions. Effect of inorganic anion on COD of aqueous solutions was different, within 2 h COD of aqueous solutions which had been input Cl-, SO42-,NO3- , HCO3- , HZPO4- , increased 6.62, 0.26, 0.03, 0.29 and 0.45 times respectively than that hadn't been put into.%TiO2-膨润土光催化降解水溶液中阴离子表面活性剂十二烷基苯磺酸钠(SDBS)的效率较高,Cl-、SO42-、NO3-、HC3-、H2PO4-是水体中常见的阴离子,这些阴离子对降解效果的影响直接影响该技术的实际应用.分别投加36 mmol/L上述阴离子的钠盐到SDBS水溶液中,紫外光照射溶液2h,比较投加与不投加的SDBS去除效果差异,结果表明:(1)水溶液中上述阴离子对TiO2-膨润土降解SDBS的效果都有不利影响,其中HCO3影响最大,其次是H2PO4_,

  14. An assessment of the use of native and denatured forms of okra seed proteins as coagulants in drinking water treatment.

    Science.gov (United States)

    Jones, Alfred Ndahi; Bridgeman, John

    2016-10-01

    The effects of temperature, storage time and water pH on the coagulation performance of okra seed protein in water treatment were assessed. In a jar test experiment, okra salt extract achieved a notable improvement in treatment efficiency with storage time and showed good performance in quality after thermal treatment at 60, 97 and 140 °C temperatures for 6, 4 and 2 hours, respectively. The performance improvement of more than 8% is considered to be due to the denaturation and subsequent removal of coagulation-hindering proteins in okra seed. Furthermore, the results of a sodium dodecyl sulphate polyacrylamide gel electrophoresis analysis show two distinctive bands of protein responsible for the coagulation process after denaturation. It was further shown that at optimal coagulant dose, the pH of the treated water remained unaffected as a result of the protein's buffering capability during coagulation. Therefore, denatured okra seed exhibited improved performance compared to the native crude extract and offers clear benefits as a water treatment coagulant.

  15. Spectroscopy and computational studies on the interaction of octyl, dodecyl, and hexadecyl derivatives of anionic and cationic surfactants with adenosine deaminase.

    Science.gov (United States)

    Ajloo, Davood; Mahmoodabadi, Najmeh; Ghadamgahi, Maryam; Saboury, Ali Akbar

    2016-07-01

    Effects of sodium (octyl, dodecyl, hexadecyl) sulfate and their cationic analogous on the structure of adenosine deaminase (ADA) were investigated by fluorescence and circular dichroism spectroscopy as well as molecular dynamics simulation and docking calculation. Root-mean-square derivations, radius of gyration, solvent accessible surface area, and radial distribution function were obtained. The results showed that anionic and cationic surfactants reduce protein stability. Cationic surfactants have more effect on the ADA structure in comparison with anionic surfactants. More concentration and longer surfactants are parallel to higher denaturation. Furthermore, aggregation in the presence of anionic surfactants is more than cationic surfactants. Docking data showed that longer surfactants have more interaction energy and smaller ones bound to the active site.

  16. Detection of enzymes active on various beta-1,3-glucans after denaturing polyacrylamide gel electrophoresis.

    Science.gov (United States)

    Trudel, J; Grenier, J; Asselin, A

    1998-07-01

    Enzymes were assayed for glucanase activity after denaturing sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) in gels containing beta-1,3-glucans embedded as substrate. Lentinan, curdlan, paramylon, baker's yeast alkali-insoluble glucan, baker's yeast alkali-soluble glucan and carboxymethyl (CM)-pachyman were compared to oligomeric laminarin, which is the usual substrate for assaying beta-1,3-glucanase activities. Detecting enzyme activities by aniline blue fluorescent staining was also compared with the staining of released reducing sugars by 2,3,5-triphenyltetrazolium chloride (TTC). For the nonreduced proteins, the Driselase extract exhibited one major band at 32.5 kDa and one less intense band at 23 kDa for most substrates with the two detection procedures. No Lyticase enzyme was detected in either detection procedures for all tested substrates. For barley enzymes, no activity was revealed after aniline blue staining while one undescribed 19 kDa glucanase activity was best shown after TTC staining with curdlan, paramylon and CM-pachyman as substrates. In the case of reduced proteins, the Lyticase extract yielded three bands (33, 36 and 46 kDa) on several substrates with both detection procedures. This was the same for the barley leaf extract (32, 36 and 39 kDa). The Driselase extract showed one 42 kDa band. Many enzymes active on beta-1,3-glucans are thus best revealed when proteins are denatured and reduced and when protein renaturation after SDS-PAGE involves a pH 8.0 treatment and the inclusion of 1 mM cysteine in buffers. However, some enzymes are only detected when proteins are denatured without reduction. Finally, the use of various polymeric beta-1,3-glucan substrates different from oligomeric laminarin is necessary to detect new types of enzymes such as the 19 kDa barley glucanase.

  17. 分子动力学模拟研究盐离子对十二烷基硫酸钠胶束溶液中亲水亲油协调机制的影响%Molecular Dynamics Simulation of Effect of Salt on the Compromise of Hydrophilic and Hydrophobic Interactions in Sodium Dodecyl Sulfate Micelle Solutions

    Institute of Scientific and Technical Information of China (English)

    高健; 任瑛; 葛蔚

    2009-01-01

    The presence of salt has a profound effect on the size, shape and structure of sodium dodecyl sulfate (SDS) micelles. There have been a great number of experiments on SDS micelles in the presence and absence of salt to study this complex problem. Unfortunately, it is not clear yet how electrolyte ions influence the structure of micelles. By describing the compromise between dominant mechanisms, a simplified atomic model of SDS in presence of salt has been developed and the molecular dynamics (MD) simulations of two series of systems with different concentrations of salt and charges of ion have been performed. Polydispersity of micelle size is founded at relatively high concentration of SDS and low charge of cation. Although the counter-ion pairs with head groups are formed, the transition of micelle shape is not observed because the charge of cation is not enough to neutralize the polar of micelle surface.

  18. Synthesis of protons exchange polymeric membranes via co-poly-esters doped with sodium dodecyl sulfate for application in PEM fuel cells; Sintese de membranas polimericas condutoras de protons por imobilizacao de MDs em copoliesteres para aplicacao em PEM-FC

    Energy Technology Data Exchange (ETDEWEB)

    Fiuza, R.A.; Brioude, M.M.; Bresciani, D.; Jose, N.M.; Boaventura, J.S. [Universidade Federal da Bahia (IQ/UFBA), Salvador, BA (Brazil). Inst. de Quimica

    2008-07-01

    Polymers are largely studied for use in PEM-type fuel cell (Proton Exchange membrane, PEMFC). These fuel cells are based on polymer membranes as electrolyte, also called protons conductor. This work developed co-polyesters made electrical conductors by doping with sodium dodecyl sulfate. The copolymers were synthesized from the copolymerization of terephthalic and adipic acids with glycerol. The material was processed in a reactor and shaped by hot pressing, yielding homogeneous and flexible plates, with excellent surface finish. The co-polyesters were analyzed by SEM, FTIR, TG, DSC, and XRD. The thermal analysis showed that the composites were thermally stable up to about 250 deg C. The micrographics revealed the MDS homogeneously dispersed in the polymeric matrix. These copolymers showed electrical conductivity between 10-7 to 10-1 S/cm, suggesting strong potential use in PEM fuel cells. (author)

  19. Protein denaturation due to the action of surfactants: a study by SAXS and ITC

    Energy Technology Data Exchange (ETDEWEB)

    Oseliero Filho, Pedro Leonidas; Oliveira, Cristiano Luis Pinto de [Universidade de Sao Paulo (USP), SP (Brazil); Pedersen, Jan Skov; Otzen, Daniel Erik [University of Aarhus (Denmark)

    2012-07-01

    Full text: Proteins are the major constituent of biological systems along with carbohydrates, lipids and nucleic acids (DNA and RNA). According to their structure and composition, proteins perform several functions in the organism, starting from the macroscopic level, with participation on the olfaction of animals, down to the cellular level, allocated in the membrane and making the connection between extra and intracellular environment. The function of a protein (which may be enzymatic, hormonal, structural, energetic, transport etc) is related to several factors including its structure (primary, secondary, tertiary or quaternary). Denaturation occurs when the secondary structure and/or tertiary is lost, which is almost always followed by the loss of the associated biological function. Temperature, pH and the action of surfactants influence the process of the denaturation. The influence of surfactants to the protein structure and function is the aim of this work. Therefore we are using an isolated protein, {alpha}-lactalbumin, that is found in the milk and whose function is related to the synthesis of galactose. The purpose is to characterize, in a thermodynamic-structural point of view, the denaturation of alpha-lactalbumin in the presence of surfactants anionic (sodium dodecyl sulfate - SDS), cationic (tetradecyltrimethylammonium bromide - TTAB), zwitterionic (2-diheptanoyl-sn-glycero-3- phosphocholine - DHPC) and nonionic (decyl-{beta}-D-Maltopyranoside - DM). The isothermal titration calorimetry (ITC) technique, which provides information of structural changes from changes in energy, represents the starting point for the study, while the technique of small angle X-ray scattering (SAXS) provides information about the structural characteristics of surfactant-protein complexes formed at each step of the denaturation process. The data analysis is in the initial stage, but it was possible to obtain general parameters related to the complex formed from the

  20. Ecotoxicological assessment of the pharmaceutical fluoxetine hydrochloride and the surfactant dodecyl sodium sulfate after their submission to ionizing radiation treatment; Avaliacao ecotoxicologica do farmaco cloridrato de fluoxetina e do surfactante dodecil sulfato de sodio quando submetidos a tratamento por radiacao ionizante

    Energy Technology Data Exchange (ETDEWEB)

    Santos, Dymes Rafael Alves dos

    2011-07-01

    The use of pharmaceuticals and personal care products and the consequent and continuous input of this substances in the environment generates an increasing need to investigate the presence, behavior and the effects on aquatic biota, as well as new ways to treat effluents containing such substances. Fluoxetine hydrochloride is an active ingredient used in the treatment of depressive disorders and anxiety. As the surfactant sodium dodecyl sulfate is present in many cleaning and personal care products. The present study aimed on assessing the acute toxicity of fluoxetine hydrochloride, sodium dodecyl sulfate and the mixture of both to the aquatic organisms Hyalella azteca, Daphnia similis and Vibrio ficheri. Reducing the toxicity of fluoxetine and the mixture after treatment with ionizing radiation from industrial electron beam accelerator has also been the focus of this study. For Daphnia similis the average values of CE50-4{sub 8h} found for the non-irradiated drug, surfactant and mixture were 14.4 %, 9.62 % and 13.8 %, respectively. After irradiation of the substances, the dose 5 kGy proved itself to be the most effective dose for the treatment of the drug and the mixture as it was obtained the mean values for CE50{sub 48h} 84.60 % and > 90 %, respectively. For Hyalella azteca the acute toxicity tests were performed for water column with duration of 96 hours, the mean values for CE50{sub 96h} found for the drug, the surfactant and the mixture non-irradiated were 5.63 %, 19.29 %, 6.27 %, respectively. For the drug fluoxetine and the mixture irradiated with 5 kGy, it was obtained 69.57 % and 77.7 %, respectively. For Vibrio ficheri the acute toxicity tests for the untreated drug and the drug irradiated with 5 kGy it was obtained CE50{sub 15min} of 6.9 % and 32.88 % respectively. These results presented a reduction of the acute toxicity of the test-substances after irradiation. (author)

  1. Complexation between dodecyl sulfate surfactant and zein protein in solution.

    Science.gov (United States)

    Ruso, Juan M; Deo, Namita; Somasundaran, P

    2004-10-12

    Interactions between sodium dodecyl sulfate and zein protein, a model system for the understanding of the effect of surfactants on skin, were investigated using a range of techniques involving UV-vis spectroscopy, TOC (total organic carbon analysis), electrophoresis, and static and dynamic light scattering. Zein protein was solubilized by SDS. The adsorption of SDS onto insoluble protein fraction caused the zeta potential of the complex to become more negative. From these values, we calculated the Gibbs energy of absorption, which decreases when the SDS concentration is raised. Finally the structure of the complex, based on the analysis by static and dynamic light scattering, is proposed to be rod like.

  2. Proteinograma sérico de bezerros recém-nascidos da raça Holandesa obtido por eletroforese em gel de poliacrilamida Serum protein concentration in newborn Holstein calves determined by means of sodium dodecyl sulphate-polyacrylamide gel electrophoresis

    Directory of Open Access Journals (Sweden)

    J.J. Fagliari

    2006-06-01

    Full Text Available The serum protein concentration of newborn Holstein calves determined by means of sodium dodecyl sulphate-polyacrylamide (SDS-PAGE was studied. Blood samples from 40 healthy newborn calves were obtained 48 hours after birth. Calves had been given 3 liters of colostrum within 2 hours after birth, following by dose corresponding by 15% of animal weight each 24 hours. The results showed three different proteinograms: 19 calves had 14 proteins with molecular weights (MW ranging from 28,000 D to 170,000D (proteinogram 1; 11 calves had 14 proteins with MW ranging from 18,000 to 170,000 D (proteinogram 1; and 10 calves had 12 proteins with MW ranging from 28,000 D to 170,000 D (proteinogram 3. The three groups presented similar IgG levels. The highest serum concentration of ceruloplasmin were verified in proteinogram 3, which had the lowest serum level of protein with MW 58,000D. It was verified a1-antitrypsin only in proteinogram 2, which had no proteins with MW of 42,000 D and 37,000D. The highest serum concentrations of IgA and protein with MW 58,000 D, and the lowest serum levels of transferrin, haptoglobin, and acid glycoprotein were verified in proteinogram 3. Measurement of serum protein concentrations by SDS-PAGE may be useful in monitoring the occurrence of hypogammaglobulinemia and the neonatal disease in calves.

  3. Poly[bis(μ3-dodecyl sulfatocalcium

    Directory of Open Access Journals (Sweden)

    Genta Sakane

    2010-07-01

    Full Text Available In the title compound [Ca(C12H25O4S2]n, the unique CaII ion lies on an inversion center and is coordinated in a slightly distorted octahedral environment by six O atoms from dodecyl sulfate anions. The crystal structure is based on hydrocarbon (dodecyl sulfate layers which sandwich the CaII ions. Within the layers, the hydrocarbon zigzag chains are parallel to one another and interact via van der Waals forces.

  4. Virus inactivation by protein denaturants used in affinity chromatography.

    Science.gov (United States)

    Roberts, Peter L; Lloyd, David

    2007-10-01

    Virus inactivation by a number of protein denaturants commonly used in gel affinity chromatography for protein elution and gel recycling has been investigated. The enveloped viruses Sindbis, herpes simplex-1 and vaccinia, and the non-enveloped virus polio-1 were effectively inactivated by 0.5 M sodium hydroxide, 6 M guanidinium thiocyanate, 8 M urea and 70% ethanol. However, pH 2.6, 3 M sodium thiocyanate, 6 M guanidinium chloride and 20% ethanol, while effectively inactivating the enveloped viruses, did not inactivate polio-1. These studies demonstrate that protein denaturants are generally effective for virus inactivation but with the limitation that only some may inactivate non-enveloped viruses. The use of protein denaturants, together with virus reduction steps in the manufacturing process should ensure that viral cross contamination between manufacturing batches of therapeutic biological products is prevented and the safety of the product ensured.

  5. Determination of Cd(II, Zn(II and Ag(Iin different matrixes after solid phase extraction on sodium dodecyl sulfate(SDS-coated alumina as their 2,3 Di Hydro 2,3 paratolylQinazoline (1 H- 4 one (DPTQO by Flame atomic absorption spectrometric

    Directory of Open Access Journals (Sweden)

    Farveh Raoufi

    2016-03-01

    Full Text Available A sensitive and selective solid phase extraction procedure for the determination of traces of Cd(II, Zn(II and Ag(I ions has been developed. An alumina-sodium dodecyl sulfate (SDS coated on with 2,3 Di Hydro 2,3 paratolylQinazoline (1 H- 4 one (DPTQO. The influences of the analytical parameters including pH and sample volume were investigated.Common coexisting ions did not interfere on the separation and determination of analytes under study. The adsorbed analytes were desorbed by using 6mL of 4 mol L−1 nitric acid. The responses are linear 0.02–0.85 µg mL-1 for Cd2+ ion0.01–0.90 µg mL-1 for Zn2+and0.02–0.92µg mL-1for Ag+ detection limit for Cd(II, Zn(II and Ag(I ions were found to be 1.4, 1.3 and1.12(ng mL-1, respectively.It was found that the recovery for Cd2+, Zn2+and Ag+ ions were 97.7, 98.2 and 98.0 with RSD of 1.9, 1.8 and 1.7. It was also observed that recovery for repeated recovery on the same solid phase not varies more than 3%. The presented procedurewas successfully applied for determination of analytes in radiology wastewater, amalgam, natural water and blood samples.

  6. Stabilization of solutions of feather keratins by sodium dodecyl sulphate

    NARCIS (Netherlands)

    Schrooyen, P.M.M.; Dijkstra, Pieter J.; Oberthür, Radulf C.; Bantjes, A.; Bantjes, Adriaan; Feijen, Jan

    2001-01-01

    Feather keratins were extracted from chicken feathers with aqueous solutions of urea and 2-mercaptoethanol. After filtration of the insoluble residue, a feather keratin solution was obtained. Removal of 2-mercaptoethanol and urea by dialysis resulted in aggregation of the keratin polypeptide chains

  7. Transport Properties of Water and Sodium Dodecyl Sulfate (Postprint)

    Science.gov (United States)

    2013-08-01

    and boiling temperatures. Additionally, MP2f (Akin- Ojo et al., 2008, “Developing Ab Initio Quality Force Fields From Con- densed Phase Quantum...results. In the second part, we introduce the ab initio flexible water model developed by Akin- Ojo et al. [38] in 2008 using the relatively new adaptive...38] Akin- Ojo , O., Song, Y., and Wang, F., 2008, “Developing Ab Initio Quality Force Fields From Condensed Phase Quantum-Mechanics/Molecular-Mechan

  8. A Self-Assembled Nano-Structrured Peroxidase Based on Sodium Dodecyl Sulfate Nano-Micelle and Cytochrome c%十二烷基磺酸钠纳米胶团-细胞色素c自组装高效纳米结构过氧化物酶

    Institute of Scientific and Technical Information of China (English)

    黄琨; 洪军; 王玮; 肖保林; 赵莹雪; 杨卫云; 高云飞

    2012-01-01

    用阴离子表面活性剂十二烷基磺酸钠与细胞色素c自组装的方法构建了一种纳米超分子结构,观察到其具有显著的过氧化物酶活性,且在pH为10.5时达到最高.这种纳米结构过氧化物酶的催化效率为0.0219μmol/L·s.电化学方法测得其电子传递速率常数ks为0.586 s-1.这种以自组装方法构建的超分子结构不仅具有较高活性,可在天然过氧化物酶自杀性失活底物浓度较高时运用,且可固定化于电极上,实现与电极间的直接电子传递.%A nano-structured supermolecule or artificial enzyme was built self-assembly based on sodium dodecyl sulfate nano-micelle and cytochrome c. A significant peroxidase activity was observed and reached the maximum value at pH 10.5. Its catalytic efficiency was evaluated to be 0.0219 μmol/L·s. The immobilized nano-structured peroxidase modified electrode showed quasi-reversible electrochemical redox behaviors with a formal potential of (-38 ± 5) mV (vs. Ag/AgCI) at a scan rate of 0.05 V/s. The cathodic transfer coefficient and electron transfer rate constant were evaluated to be 0.51 and 0.59 s-1 respectively. The apparent Michaelis-Menten constant (Kmapp) was calculated to be 0.14 mmol/L. These results suggest that the nano-structured peroxidase not only perform a high activity as peroxidase and can be used in high concentration of hydrogen peroxide,but also can be immobilized on the electrode and realize direct electrochemical behavior.

  9. Correlation between HSP27 and CFL-1 in acute irritation induced by sodium dodecyl sulfate in keratinocytes%HSP27和CFL-1在角质细胞急性刺激反应中相关性的研究

    Institute of Scientific and Technical Information of China (English)

    胡浩; 张齐好; 邹萍; 仝雷; 黄亚东

    2011-01-01

    研究急性刺激条件下,角质细胞中热休克蛋白27(heat shock protein 27,HSP27)和Cofilin-1(CFL-1)的表达是否具有相关性,初步探讨皮肤急性刺激反应的作用机理.通过免疫印迹法检测十二烷基硫酸钠(SDS)诱发的急性刺激反应下,角质细胞中HSP27和CFL-1蛋白的表达,并通过RNAi技术验证两者之间的相关性.结果发现,急性刺激诱导HSP27表达显著下调,CFL-1显著上调;干扰HSP27后,CFL-1的表达也随着下调,SDS刺激后,则表达上调.在急性刺激性条件下,HSP27和CFL-1的表达具有一定的浓度和时间依赖性;急性刺激能影响角质细胞骨架的改变,这些改变可能是通过HSP27和CFL-1的相互作用来调节的.%The correlation between heat shock protein 27 (HSP27) and Cofilin-1 ( CFL-1 ) was studied in acute irritation induced by sodium dodecyl sulfate (SDS) in keratinocytes, which would be helpful for the mechanistic understanding of the skin irritation.The expressions of HSP27 and CFL-1 were detected by immunoblotting in keratinocytes exposed to SDS.The correlation between HSP27 and CFL-1 was validated by RNAi technology.HSP27 was significantly downregulated and CFL-1 was significantly upregulated in response to the chemical challenge.The expression of CFL-1 was significantly reduced after interference of HSP27, but it was upregulated after exposure to SDS.The expressions of HSP27 and CFL-1 showed a time-and dose-dependent manner in acute irritation.The cute irritant may alter the cytoskeleton of keratinocyte, and these changes may be regulated by the interaction between HSP27 and CFL-1.

  10. Flotation of kaolinite with dodecyl tertiary amines

    Institute of Scientific and Technical Information of China (English)

    CAO Xue-feng; LIU Chang-miao; HU Yue-hua

    2009-01-01

    The flotation of kaolinite using a series of tertiary amines (N,N-dimethyl-dodecyl amine (DRN), N,N-diethyl-dodecyl amine (DEN), N,N-dipropyl-dodecyl amine (DPN) and N,N-dibenzyl-bodecyi amine (DBN)) was investigated. The results show that the maximum recoveries of kaolinite for DEN, DPN and DRN are 93%, 88% and 84%, respectively, but that of DBN is very low. On the basis of zeta potential and FT-IR spectra, the ionization of surface hydroxyl and isomorphic exchange of surface ions account for the charging mechanisms of kaolinite surface. The adsorption mechanism of tertiary amines on kaolinite surface is mainly electrostatic. The isoelectric point (IEP) of kaolinite increases from 3.4 to some more positive points after the interaction of kaolinite with the four tertiary amines. The FT-IR spectra of kaolinite change with the presence of some new sharp shapes belonging to the tertiary amines. The inductive electronic effects and space-steric effects of -CH_3, -C_2H_5, -C_3H_7 and -C_7H_7 bonding to N atom result in different collecting power of the four tertiary amines.

  11. [DNA degradation during standard alkaline of thermal denaturation].

    Science.gov (United States)

    Drozhdeniuk, A P; Sulimova, G E; Vaniushin, B F

    1976-01-01

    Essential degradation 8 DNA (up to 10 per cent) with liberation of acid-soluble fragments takes place on the standard alkaline (0,01 M sodium phosphate, pH 12, 60 degrees, 15 min) or thermal (0.06 M sodium phosphate buffer, pH 6.8, 102 degrees C, 15 min) denaturation. This degradation is more or less selective: fraction of low molecular weight fragments, isolated by hydroxyapatite cromatography and eluted by 0.06 M sodium phosphate buffer, pH 6.8 is rich in adenine and thymine and contains about 2 times less 5-methylcytosine than the total wheat germ DNA. The degree of degradation of DNA on thermal denaturation is higher than on alkaline degradation. Therefore while studying reassociation of various DNA, one and the same standard method of DNA denaturation should be used. Besides, both the level of DNA degradation and the nature of the resulting products (fragments) should be taken into account.

  12. Avoiding adsorption of DNA to polypropylene tubes and denaturation of short DNA fragments

    OpenAIRE

    Gaillard, Claire; Strauss, Francois

    1998-01-01

    Two problems can arise when working with small quantities of DNA in polypropylene tubes: first, significant amounts of DNA can become lost by sticking to the tube walls; second, short DNA fragments tend to denature when binding to polypropylene. In addition, DNA also tends to denature upon dehydration. We have found that a simple way to solve these problems is by using polyallomer tubes instead of polypropylene and by avoiding certain salts, such as sodium acetate, when drying DNA.

  13. Effect of intensity of ultraviolet light on degradation of sodium dodecyl benzene sulfonate by TiO2-bentonite%紫外光光强对TiO2-膨润土降解十二烷基苯磺酸钠的影响

    Institute of Scientific and Technical Information of China (English)

    温淑瑶; 马敏立; 陈素云; 马占青

    2011-01-01

    在室温、电磁搅拌和6W紫外灯(距静止液面距离分别为6.5 cm、18.5 cm、30.5 cm和42.5 cm)的不同光强(在静止液面处的光强分别为700~750 μW/cm2、300~310μW/cm2、200~210 μW/cm2和110~120μW/cm2),及太阳光的不同紫外光强度照射条件下,质量分数为0.5‰的纳米TiO2-膨润土复合光催化剂对初始质量浓度为20 mg/L的十二烷基苯磺酸钠(SDBS)溶液中SDBS的降解反应表明:光强对SDBS降解的影响较大,光强越强SDBS的降解率越高、溶液的COD值降低率越大;不同光强下,TiO2-膨润土对SDBS降解反应为一级反应,符合Langmuir-Hinshelwood方程;随着光强的增大,TiO2-膨润土对SDBS降解的光催化反应速率常数增大.%Different intensities of ultraviolet light (700~750 (μW/cm2 ,300~310μ/W/cm2,200~210μW/cm2 and 110-120 μW/cm2)resulted from different distances(6.5 cm, 18.5 cm,30.5 cm and 42.5 cm ) between 6 W ultraviolet light and still solution surface respectively.Original concentration of sodium dodecyl benzene sulfonate (SDBS) was 20mg/L.Under the same condition (temperature, ultraviolet light shining period, electromagnetic mixing, Ph 6 ) and different intensities of light, the results of degradation reaction of SDBS by 0.5 TiO2-bentonite show that the effect of intensity of light on degradation is obvious.The higher the intensity of ultraviolet light, the more the SDBS was degradated.The higher the intensity of ultraviolet light, the more the chemical oxide demand of solution decreased.The degradation reaction was first-order reaction.Its law of dynamics accorded with Langmuir-Hinshelwood equation.The higher the intensity of ultraviolet light, the bigger the speed coefficient of photocatalytic reaction between SDBS and TiO2-bentonite.

  14. Investigation on the Interaction of Sodium Dodecyl Sulfate with Poly(Ethylene Oxide) by Electron Spin Resonance and UV Spectrum%顺磁共振和紫外光谱法研究SDS-PEO体系的相互作用

    Institute of Scientific and Technical Information of China (English)

    海明潭; 韩布兴; 闫海科

    2001-01-01

    合成更疏水的自旋探针4-羰基2,2,6,6四甲基哌啶氮氧自由基2,4-二硝基苯腙.用顺磁共振(ESR)和紫外光谱法研究了十二烷基硫酸钠(SDS)0.5%(w,质量分数)聚氧乙烯(PEO)体系的分子间相互作用.ESR结果表明,此水溶液体系的微极性随SDS浓度增大而减小,并且SDS与PEO聚集体具有更加紧密的堆积结构使其结合处具有较大的微粘性,SDS与PEO间的相互作用导致PEO分子链伸展.UV表明自旋探针分子可能靠近胶束的表面存在,2,4-二硝基苯肼基团可能位于靠近SDS的硫酸根基团,定向于SDS胶束的表面,氮氧自由基基团短距离渗透到SDS胶束的碳氢核.%ESR and UV spectrum of the aqueous solution of sodium dodecyl sulfate(SDS)/poly(ethylene oxide)(PEO) were measured at room temperature respectively, the concentration of PEO was 0.5% (mass fraction), and the concentration of SDS (mSDS) was up to 50 mmol· kg- 1. 2,4-dinitrophylhydrazone of 2,2,6,6-tetramethyl-4-piperidine-1-oxyl (Tempone-DNPH) was synthesized and used as ESR probe. The binding site of SDS-PEO interaction, the micropolarity and microviscosity information of the microenvironments have been determined by ESR. UV spectrum gives information on the environment of 2,4-dinitrophylhydrazone group. The hyperfine coupling constant and the rotational correlation time of the spin probe reflect the microenvironment of the polymer-micelle aggregates. The micropolarity of the solutions decreases with increasing SDS concentration, the polymer-micelle aggregate forms a more compact structure at the binding site and the binding site between PEO and SDS micelles yields a strong increase of the microviscosity at the micelle-polymer interface. Spin probe is located near the surface of the micelle. 2,4-dinitrophylhydrazone group may be adjacent to the sulphate groups, and the nitroxide group penetrates a small distance into the hydrocarbon core of the micelle

  15. 十二烷基苯磺酸钠-异辛烷-正辛醇反胶束萃取苦参生物碱的研究%Extraction of Alkaloids in Sophora Flavescens Ait by Reverse Micelle of Sodium Dodecyl Benzene Sulfonate/Isooctane/n-Octanol

    Institute of Scientific and Technical Information of China (English)

    刘小琴; 范华均; 佘旭辉; 张来凤; 王李平

    2012-01-01

    利用阴离子表面活性剂十二烷基苯磺酸钠(SDBS)与溶剂异辛烷和助溶剂正辛醇形成反胶束体系,用于苦参生物碱的萃取分离.研究了pH值、表面活性剂浓度、增溶水量W0、盐种类及浓度等因素对萃取的影响.结果表明:SDBS-异辛烷-正辛醇反胶束体系对苦参生物碱具有良好的选择性和较高萃取率,在pH 5.0,增溶水量W0 25,0.05 mol/L SDBS,0.05 mol/L KCl,室温,萃取时间5 min,反萃取时间20 min的最佳萃取条件下,氧化苦参碱、氧化槐果碱、槐定碱、苦参碱、槐果碱5种生物碱及总生物碱的萃取率和RSD分别在74.1%~87.2%和0.63%~3.0%之间.本方法选择性高,操作简便.%A method of reverse micelle extraction of alkaloids in Sophora Flavescens Ait has been developed using the reverse micelle system of sodium dodecyl benzene sulfonate(SDBS)/isooctane/ n-octanol. The experimental conditions such as pH, water content Wo, extraction time and temperature, the concentration of surfactant and salts were optimized. With the help of high performance liquid chromatography, the results showed that the reverse micelle formed by SDBS, isooctane and n-octanol can more effectively extract alkaloids than others. The optimum extraction conditions were as follows: pH 5. 0, 25 of water content Wo, 0. 05 mol/L of SDBS concentration, 0. 05 mol/L of KC1 concentration, 5 min of forward-extraction time and 20 min of backward-extraction time at room temperature. The method has been applied to separate and purify alkaloids from the extract by water with pressurized microwave-assisted extraction. Under the optimum conditions, the extraction yields of oxymatrine, n-oxysophocarpine, sophoridine, matrine, sophocarpine and total alkaloids in Sophora Flavescens Ait were between 74. 1% and 87. 2%, RSDs of their reproducibility were from 0. 6% to 3. 0%. The method is higher selectivity, and easy to operate.

  16. Interactions between dodecyl phosphates and hydroxyapatite or tooth enamel: relevance to inhibition of dental erosion.

    Science.gov (United States)

    Jones, Siân B; Barbour, Michele E; Shellis, R Peter; Rees, Gareth D

    2014-05-01

    Tooth surface modification is a potential method of preventing dental erosion, a form of excessive tooth wear facilitated by softening of tooth surfaces through the direct action of acids, mainly of dietary origin. We have previously shown that dodecyl phosphates (DPs) effectively inhibit dissolution of native surfaces of hydroxyapatite (the type mineral for dental enamel) and show good substantivity. However, adsorbed saliva also inhibits dissolution and DPs did not augment this effect, which suggests that DPs and saliva interact at the hydroxyapatite surface. In the present study the adsorption and desorption of potassium and sodium dodecyl phosphates or sodium dodecyl sulphate (SDS) to hydroxyapatite and human tooth enamel powder, both native and pre-treated with saliva, were studied by high performance liquid chromatography-mass Spectrometry. Thermo gravimetric analysis was used to analyse residual saliva and surfactant on the substrates. Both DPs showed a higher affinity than SDS for both hydroxyapatite and enamel, and little DP was desorbed by washing with water. SDS was readily desorbed from hydroxyapatite, suggesting that the phosphate head group is essential for strong binding to this substrate. However, SDS was not desorbed from enamel, so that this substrate has surface properties different from those of hydroxyapatite. The presence of a salivary coating had little or no effect on adsorption of the DPs, but treatment with DPs partly desorbed saliva; this could account for the failure of DPs to increase the dissolution inhibition due to adsorbed saliva.

  17. Experimental Investigation on Pool Boiling Heat Transfer With Ammonium Dodecyl Sulfate

    Directory of Open Access Journals (Sweden)

    Mr.P. Atcha Rao

    2015-11-01

    Full Text Available We have so many applications related to Pool Boiling. The Pool Boiling is mostly useful in arid areas to produce drinking water from impure water like sea water by distillation process. It is very difficult to distill the only water which having high surface tension. The surface tension is important factor to affect heat transfer enhancement in pool boiling. By reducing the surface tension we can increase the heat transfer rate in pool boiling. From so many years we are using surfactants domestically. It is proven previously by experiments that the addition of little amount of surfactant reduces the surface tension and increase the rate of heat transfer. There are different groups of surfactants. From those I‟m conducting experimentation with anionic surfactant Ammonium Dodecyl Sulfate (ADS, which is most human friendly and three times best soluble than Sodium Dodecyl Sulfate, to test the heat transfer enhancement.

  18. Single DNA denaturation and bubble dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Metzler, Ralf [Physics Department, Technical University of Munich, James Franck Strasse, 85747 Garching (Germany); Ambjoernsson, Tobias [Chemistry Department, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139 (United States); Hanke, Andreas [Department of Physics and Astronomy, University of Texas, 80 Fort Brown, Brownsville (United States); Fogedby, Hans C [Department of Physics and Astronomy, University of Arhus, Ny Munkegade, 8000 Arhus C (Denmark)], E-mail: metz@ph.tum.de

    2009-01-21

    While the Watson-Crick double-strand is the thermodynamically stable state of DNA in a wide range of temperature and salt conditions, even at physiological conditions local denaturation bubbles may open up spontaneously due to thermal activation. By raising the ambient temperature, titration, or by external forces in single molecule setups bubbles proliferate until full denaturation of the DNA occurs. Based on the Poland-Scheraga model we investigate both the equilibrium transition of DNA denaturation and the dynamics of the denaturation bubbles with respect to recent single DNA chain experiments for situations below, at, and above the denaturation transition. We also propose a new single molecule setup based on DNA constructs with two bubble zones to measure the bubble coalescence and extract the physical parameters relevant to DNA breathing. Finally we consider the interplay between denaturation bubbles and selectively single-stranded DNA binding proteins.

  19. Single DNA denaturation and bubble dynamics

    DEFF Research Database (Denmark)

    Metzler, Ralf; Ambjörnsson, Tobias; Hanke, Andreas

    2009-01-01

    for situations below, at, and above the denaturation transition. We also propose a new single molecule setup based on DNA constructs with two bubble zones to measure the bubble coalescence and extract the physical parameters relevant to DNA breathing. Finally we consider the interplay between denaturation......While the Watson-Crick double-strand is the thermodynamically stable state of DNA in a wide range of temperature and salt conditions, even at physiological conditions local denaturation bubbles may open up spontaneously due to thermal activation. By raising the ambient temperature, titration......, or by external forces in single molecule setups bubbles proliferate until full denaturation of the DNA occurs. Based on the Poland-Scheraga model we investigate both the equilibrium transition of DNA denaturation and the dynamics of the denaturation bubbles with respect to recent single DNA chain experiments...

  20. The dynamics of the DNA denaturation transition

    CERN Document Server

    van Erp, Titus S

    2012-01-01

    The dynamics of the DNA denaturation is studied using the Peyrard-Bishop-Dauxois model. The denaturation rate of double stranded polymers decreases exponentially as function of length below the denaturation temperature. Above Tc, the rate shows a minimum, but then increases as function of length. We also examine the influence of sequence and solvent friction. Molecules having the same number of weak and strong base-pairs can have significantly different opening rates depending on the order of base-pairs.

  1. Bubbles and denaturation in DNA

    CERN Document Server

    Van Erp, T S; Peyrard, M; Erp, Titus S. van; Cuesta-Lopez, Santiago; Peyrard, Michel

    2006-01-01

    The local opening of DNA is an intriguing phenomenon from a statistical physics point of view, but is also essential for its biological function. For instance, the transcription and replication of our genetic code can not take place without the unwinding of the DNA double helix. Although these biological processes are driven by proteins, there might well be a relation between these biological openings and the spontaneous bubble formation due to thermal fluctuations. Mesoscopic models, like the Peyrard-Bishop-Dauxois model, have fairly accurately reproduced some experimental denaturation curves and the sharp phase transition in the thermodynamic limit. It is, hence, tempting to see whether these models could be used to predict the biological activity of DNA. In a previous study, we introduced a method that allows to obtain very accurate results on this subject, which showed that some previous claims in this direction, based on molecular dynamics studies, were premature. This could either imply that the present...

  2. DNA denaturation in ionic solution

    Science.gov (United States)

    Maity, Arghya; Singh, Amar; Singh, Navin

    2016-05-01

    Salt or cations, present in solution play an important role in DNA denaturation and folding kinetics of DNA helix. In this work we study the thermal melting of double stranded DNA (dsDNA) molecule using Peyrard Bishop Dauxois (PBD) model. We modify the potential of H-bonding between the bases of the complimentary strands to introduce the salt and solvent effect. We choose different DNA sequences having different contents of GC pairs and calculate the melting temperatures. The melting temperature increases logarithmically with the salt concentration of the solution. The more GC base pairs in the chain enhance the stability of DNA chain at a fix salt concentration. The obtained results are in good accordance with experimental findings.

  3. Evaluation of mutation screening by heteroduplex analysis in acute intermittent porphyria: comparison with denaturing gradient gel electrophoresis.

    Science.gov (United States)

    Tchernitchko, D; Lamoril, J; Puy, H; Robreau, A M; Bogard, C; Rosipal, R; Gouya, L; Deybach, J C; Nordmann, Y

    1999-01-01

    Acute intermittent porphyria is the major autosomal dominant form of acute hepatic porphyrias. The disease is due to mutations in the gene encoding for porphobilinogen deaminase (PBGD). Many different strategies have been developed to screen for mutations. However the high prevalence (0.6 per thousand) of PBGD gene defect, the large allelic heterogeneity of mutations (n = 130), and the limitations of the PBGD enzymatic assay for asymptomatic patients' detection, require for diagnosis an efficient and easy to handle strategy for locating mutations within the PBGD gene. In a recent study the sensitivity of the denaturing gradient gel electrophoresis (DGGE) technique was 100%. However DGGE requires the preparation of gradient gels and the use of primers with long GC-clamps; thus alternative methods should be preferable in the clinical laboratory. We have compared the detection rate of DGGE with heteroduplex analysis (HA) using 16 characterized PBGD gene mutations. Six different HA conditions were used to determine the efficiency of the method, including: (1) MDE (mutation detection enhancement) gel concentration; (2) addition of urea and sodium dodecyl sulfate (SDS); (3) radioactive labelling. The sensitivity of each HA condition varied from 31 to 81% vs. 100% in DGGE analysis. HA using 1 x MDE with 15% urea with or without 0.55% SDS was the most sensitive condition. This first comparative study of DGGE and HA mutation screening methods suggests that DGGE is a more sensitive screening assay than optimized HA. However, because of its simplicity HA should be considered as an efficient alternative mutation screening method.

  4. Refolding of Denatured/Reduced Lysozyme Using Weak-Cation Exchange Chromatography

    Institute of Scientific and Technical Information of China (English)

    Yan WANG; Bo Lin GONG; Xin Du GENG

    2003-01-01

    Oxidative refolding of the denatured/reduced lysozyme was investigated by using weak-cation exchange chromatography (WCX). The stationary phase of WCX binds to the reduced lysozyme and prevented it from forming intermolecular aggregates. At the same time urea and ammonium sulfate were added to the mobile phase to increase the elution strength for lysozyme. Ammonium sulfate can more stabilize the native protein than a common eluting agent, sodium chloride. Refolding of lysozyme by using this WCX is successfully. It was simply carried out to obtain a completely and correctly refolding of the denatured lysozyme at high concentration of 20.0 mg/mL.

  5. Mobility of alkali cations in polypyrrole-dodecyl sulfate

    Energy Technology Data Exchange (ETDEWEB)

    Kupila, E.L. [Department of Chemistry, University of Turku, 20500 Turku (Finland); Kankare, J. [Department of Chemistry, University of Turku, 20500 Turku (Finland)

    1995-03-01

    Due to the immobility of the large dodecyl sulfate anion, the mobile ions in polypyrrole-dodecyl sulfate are small ions from the solution. Virgin PP-dodecyl sulfate does not contain other ionic species, but already the first reduction causes the incorporation of cations into the membrane. Using in situ AC conductimetry on a double-band platinum electrode, we show that the insertion of cations from the solution into the PP membrane proceeds as a non-conducting zone advancing from the solution interface toward the substrate. The model allows to estimate ion mobilities in the membrane giving 8.6x10{sup -7}cm{sup 2}s{sup -1}V{sup -1} for K{sup +}. (orig.)

  6. Electronic Conductivity of Polypyrrole−Dodecyl Benzene Sulfonate Complexes

    DEFF Research Database (Denmark)

    West, Keld; Bay, Lasse; Nielsen, Martin Meedom

    2004-01-01

    The electronic conductivity of the electroactive polymer polypyrrole-dodecyl benzene sulfonate (PPy-DBS) has been characterized as function of the redox level. The polymer was synthesized with different isomers of the dopant anions: the common mixed DBS tenside and three well-defined synthetic...

  7. Chemical shift prediction for denatured proteins

    Energy Technology Data Exchange (ETDEWEB)

    Prestegard, James H., E-mail: jpresteg@ccrc.uga.edu; Sahu, Sarata C.; Nkari, Wendy K.; Morris, Laura C.; Live, David; Gruta, Christian

    2013-02-15

    While chemical shift prediction has played an important role in aspects of protein NMR that include identification of secondary structure, generation of torsion angle constraints for structure determination, and assignment of resonances in spectra of intrinsically disordered proteins, interest has arisen more recently in using it in alternate assignment strategies for crosspeaks in {sup 1}H-{sup 15}N HSQC spectra of sparsely labeled proteins. One such approach involves correlation of crosspeaks in the spectrum of the native protein with those observed in the spectrum of the denatured protein, followed by assignment of the peaks in the latter spectrum. As in the case of disordered proteins, predicted chemical shifts can aid in these assignments. Some previously developed empirical formulas for chemical shift prediction have depended on basis data sets of 20 pentapeptides. In each case the central residue was varied among the 20 amino common acids, with the flanking residues held constant throughout the given series. However, previous choices of solvent conditions and flanking residues make the parameters in these formulas less than ideal for general application to denatured proteins. Here, we report {sup 1}H and {sup 15}N shifts for a set of alanine based pentapeptides under the low pH urea denaturing conditions that are more appropriate for sparse label assignments. New parameters have been derived and a Perl script was created to facilitate comparison with other parameter sets. A small, but significant, improvement in shift predictions for denatured ubiquitin is demonstrated.

  8. Rousseau's Philosophy of Transformative, "Denaturing" Education

    Science.gov (United States)

    Riley, Patrick

    2011-01-01

    Rousseau's political philosophy presents the great legislator as a civic educator who must over time transform naturally self-loving egoists into citizens animated by a general will without destroying freedom. This is an educational process which is "denaturing" but which aims to produce autonomous adults who can ultimately say to their teacher…

  9. Guanidinium-induced denaturation by breaking of salt bridges

    NARCIS (Netherlands)

    Meuzelaar, H.; Panman, M.R.; Woutersen, S.

    2015-01-01

    Despite its wide use as a denaturant, the mechanism by which guanidinium (Gdm+) induces protein unfolding remains largely unclear. Herein, we show evidence that Gdm+ can induce denaturation by disrupting salt bridges that stabilize the folded conformation. We study the Gdm+-​induced denaturation of

  10. Hysteresis in pressure-driven DNA denaturation.

    Directory of Open Access Journals (Sweden)

    Enrique Hernández-Lemus

    Full Text Available In the past, a great deal of attention has been drawn to thermal driven denaturation processes. In recent years, however, the discovery of stress-induced denaturation, observed at the one-molecule level, has revealed new insights into the complex phenomena involved in the thermo-mechanics of DNA function. Understanding the effect of local pressure variations in DNA stability is thus an appealing topic. Such processes as cellular stress, dehydration, and changes in the ionic strength of the medium could explain local pressure changes that will affect the molecular mechanics of DNA and hence its stability. In this work, a theory that accounts for hysteresis in pressure-driven DNA denaturation is proposed. We here combine an irreversible thermodynamic approach with an equation of state based on the Poisson-Boltzmann cell model. The latter one provides a good description of the osmotic pressure over a wide range of DNA concentrations. The resulting theoretical framework predicts, in general, the process of denaturation and, in particular, hysteresis curves for a DNA sequence in terms of system parameters such as salt concentration, density of DNA molecules and temperature in addition to structural and configurational states of DNA. Furthermore, this formalism can be naturally extended to more complex situations, for example, in cases where the host medium is made up of asymmetric salts or in the description of the (helical-like charge distribution along the DNA molecule. Moreover, since this study incorporates the effect of pressure through a thermodynamic analysis, much of what is known from temperature-driven experiments will shed light on the pressure-induced melting issue.

  11. The anionic biosurfactant rhamnolipid does not denature industrial enzymes

    Directory of Open Access Journals (Sweden)

    Jens Kvist Madsen

    2015-04-01

    Full Text Available Biosurfactants (BS are surface-active molecules produced by microorganisms. Their combination of useful properties and sustainable production make them promising industrial alternatives to petrochemical and oleochemical surfactants. Here we compare the impact of the anionic BS rhamnolipid (RL and the conventional/synthetic anionic surfactant sodium dodecyl sulfate (SDS on the structure and stability of three different commercially used enzymes, namely the cellulase Carezyme® (CZ, the phospholipase Lecitase Ultra® (LT and the α-amylase Stainzyme® (SZ. Our data reveal a fundamental difference in their mode of interaction. SDS shows great diversity of interaction towards the different enzymes. It efficiently unfolds both LT and CZ, but LT is unfolded by SDS through formation of SDS clusters on the protein well below the cmc, while CZ is only unfolded by bulk micelles and on average binds significantly less SDS than LT. SDS binds with even lower stoichiometry to SZ and leads to an increase in thermal stability. In contrast, RL does not affect the tertiary or secondary structure of any enzyme at room temperature, has little impact on thermal stability and only binds detectably (but at low stoichiometries to SZ. Furthermore all enzymes maintain activity at both monomeric and micellar concentrations of RL. We conclude that RL, despite its anionic charge, is a surfactant that does not compromise the structural integrity of industrially relevant proteins. This makes RL a promising alternative to current synthetic anionic surfactants in a wide range of commercial applications.

  12. DSC study of denaturation of β-lactoglobulin B

    Institute of Scientific and Technical Information of China (English)

    王邦宁; 谈夫

    1995-01-01

    The denaturation of bovine β-lactoglobulin B (β-Lg B) has been studied in phosphate solutions with various concentrations of GuHCl with differential scanning calorimetry The experiments demonstrated that the presence of GuHCl made the β-Lg B undergo both cold denaturation and heat denaturation under the condition of a high concentration of the protein. The enthalpy changes of both kinds of denaturation exhibit opposite signs. Both the cold denaturation and the renaturation of the protein are reproducible, but its heat denaturation is irreversible. The cooperation among monomer molecules of the protein is involved in its heat denaturation The heat denaturation of the protein can be represented by the thermodynamic model Nc D→F. The activation energy of heat denaturation is 285 kJ/mol, which imples that the depression of temperature and enthalpy of heat denaturation of the P-Lg B does not result from decreasing considerably the activation energy by GuHCl As for the cold denaturation of the protein, es

  13. Genotoxic effects of 2-dodecyl cyclobutanone; Genotoxizitaet von 2-Dodecylcyclobutanon

    Energy Technology Data Exchange (ETDEWEB)

    Delincee, H.; Pool-Zobel, B.L.; Rechkemmer, G. [Bundesforschungsanstalt fuer Ernaehrung, Karlsruhe (Germany). Inst. fuer Ernaehrungsphysiologie

    1999-07-01

    The paper reports in vivo experiments with rats who received two different doses of 2-dodecyl cyclobutane administered orally. 16 hours after administration, colon cells were isolated and examined for DNA damage by means of the comet assay. No cytotoxic effects were found with the trypan blue exclusion test. When the '% tail intensity' or the 'tail moment' were used for quantitative analysis with the comet assay, it was found that similar results are obtained for the test group which received a lower dose of 2-dodecyl cyclobutane (1.12 mg/kg of body weight) and the control group which received 2% dimethyl sulfoxide. Administration of higher concentrations of the 2-dodecyl cyclobutane (14.9 mg/kg of body weight) was found to induce minor, but significant DNA damage in the test group. Further experiments will be needed in order to assess the relevance of these results for assessment of health risks due to consumption of irradiated food. (orig./CB) [German] In dieser Arbeit wurden in vivo-Versuche an Ratten, die zwei Dosierungen an 2-Dodecylcyclobutanon per Schlundsonde erhielten, durchgefuehrt. Nach 16-stuendiger Einwirkung wurden Kolonzellen aus den Ratten isoliert und mit Hilfe des Comet Assay auf DNA-Schaeden analysiert. Zytotoxische Effekte wurden bei der Anwendung des Trypanblau-Ausschlusstests nicht festgestellt. Wenn im Comet Assay zur quantitativen Auswertung das '% tail intensity' oder das 'tail moment' eingesetzt wurde, wurde bei der Versuchsgruppe, die eine niedrigere Konzentration des 2-Dodecylcyclobutanons (1,12 mg/kg Koerpergewicht) erhielt, aehnliche Werte wie bei der Kontrollgruppe, die 2% Dimethylsulfoxid verabreicht bekamen, beobachtet. Bei der hoeheren Konzentration des 2-Dodecylcyclobutanons (14,9 mg/kg Koerpergewicht) wurde in der Versuchsgruppe eine geringe, aber signifikante DNA-Schaedigung festgestellt. Weiterfuehrende Untersuchungen sind erforderlich, um die Relevanz dieser Ergebnisse fuer eine

  14. Copolymerization of Styrene with Dodecyl Methacrylate and Octadecyl Methacrylate

    OpenAIRE

    Vidović, Elvira; SARIĆ, Karla; JANOVIĆ, Zvonimir

    2002-01-01

    Styrene (Sty) was copolymerized with dodecyl methacrylate (DDMA) and with octadecyl methacrylate (ODMA) in toluene solution using 2,2'-azobis(isobutyronitrile) (AIBN) as a free radical initiator over a wide composition and conversion range. The copolymer composi-tion was determined from NMR spectra. The copolymerization reactivity ratios were found to be r1 = 0.52 (Sty) and r2 = 0.42 (DDMA) for the Sty-DDMA system, and r1 = 0.58 (Sty) and r2 = 0.45 (ODMA) for the Sty-ODMA system, showing a te...

  15. Supercoiling induces denaturation bubbles in circular DNA.

    Science.gov (United States)

    Jeon, Jae-Hyung; Adamcik, Jozef; Dietler, Giovanni; Metzler, Ralf

    2010-11-12

    We present a theoretical framework for the thermodynamic properties of supercoiling-induced denaturation bubbles in circular double-stranded DNA molecules. We explore how DNA supercoiling, ambient salt concentration, and sequence heterogeneity impact on the bubble occurrence. An analytical derivation of the probability distribution to find multiple bubbles is derived and the relevance for supercoiled DNA discussed. We show that in vivo sustained DNA bubbles are likely to occur due to partial twist release in regions rich in weaker AT base pairs. Single DNA plasmid imaging experiments clearly demonstrate the existence of bubbles in free solution.

  16. 27 CFR 21.151 - List of denaturants authorized for denatured spirits.

    Science.gov (United States)

    2010-04-01

    ... TOBACCO TAX AND TRADE BUREAU, DEPARTMENT OF THE TREASURY LIQUORS FORMULAS FOR DENATURED ALCOHOL AND RUM... (Glycerol), U.S.P S.D.A. 31-A. Green soap, U.S.P S.D.A. 27-B. Guaiacol, N.F.X S.D.A. 38-B. Heptane C.D.A....

  17. 78 FR 38628 - Reclassification of Specially Denatured Spirits and Completely Denatured Alcohol Formulas and...

    Science.gov (United States)

    2013-06-27

    ... alcohol. 13-A 10 gallons of ethyl ether. 19 100 gallons of ethyl ether. 23-A 8 gallons of acetone, U.S.P... alcohol. 32 5 gallons of ethyl ether. 35-A 4.25 gallons of ethyl acetate having an ester content of 100... regulations regarding the production, warehousing, denaturing, distribution, sale, export, and use...

  18. Partially folded intermediates during trypsinogen denaturation

    Directory of Open Access Journals (Sweden)

    Martins N.F.

    1999-01-01

    Full Text Available The equilibrium unfolding of bovine trypsinogen was studied by circular dichroism, differential spectra and size exclusion HPLC. The change in free energy of denaturation was = 6.99 ± 1.40 kcal/mol for guanidine hydrochloride and = 6.37 ± 0.57 kcal/mol for urea. Satisfactory fits of equilibrium unfolding transitions required a three-state model involving an intermediate in addition to the native and unfolded forms. Size exclusion HPLC allowed the detection of an intermediate population of trypsinogen whose Stokes radii varied from 24.1 ± 0.4 Å to 26.0 ± 0.3 Å for 1.5 M and 2.5 M guanidine hydrochloride, respectively. During urea denaturation, the range of Stokes radii varied from 23.9 ± 0.3 Å to 25.7 ± 0.6 Å for 4.0 M and 6.0 M urea, respectively. Maximal intrinsic fluorescence was observed at about 3.8 M urea with 8-aniline-1-naphthalene sulfonate (ANS binding. These experimental data indicate that the unfolding of bovine trypsinogen is not a simple transition and suggest that the equilibrium intermediate population comprises one intermediate that may be characterized as a molten globule. To obtain further insight by studying intermediates representing different stages of unfolding, we hope to gain a better understanding of the complex interrelations between protein conformation and energetics.

  19. Differentiation and distribution of colistin- and sodium dodecyl sulfate-tolerant cells in Pseudomonas aeruginosa biofilms

    DEFF Research Database (Denmark)

    Haagensen, Janus Anders Juul; Klausen, M; Ernst, RK

    2007-01-01

    During Pseudomonas aeruginosa flow cell biofilm development, the cell population differentiates into a nonmotile subpopulation which forms microcolonies and a migrating subpopulation which eventually colonizes the top of the microcolonies, resulting in the development of mushroom-shaped multicell......During Pseudomonas aeruginosa flow cell biofilm development, the cell population differentiates into a nonmotile subpopulation which forms microcolonies and a migrating subpopulation which eventually colonizes the top of the microcolonies, resulting in the development of mushroom......-targeting antibacterial agents. All biofilm-associated cells were sensitive to the antibacterial agents when tested in standard plate assays. A mutation eliminating the production of type IV pili, and hence surface-associated motility, prevented the formation of regular mushroom-shaped structures in the flow cell...

  20. Degradation of sodium dodecyl sulphate in water using solar driven Fenton-like advanced oxidation processes

    Energy Technology Data Exchange (ETDEWEB)

    Bandala, Erick R. [Instituto Mexicano de Tecnologia del Agua, Paseo Cuauhnahuac 8532, Progreso Jiutepec, Morelos 62550 (Mexico)], E-mail: ebandala@tlaloc.imta.mx; Pelaez, Miguel A.; Salgado, Maria J. [Instituto Mexicano de Tecnologia del Agua, Paseo Cuauhnahuac 8532, Progreso Jiutepec, Morelos 62550 (Mexico); Torres, Luis [Instituto de Ingenieria, Universidad Nacional Autonoma de Mexico (UNAM) (Mexico)

    2008-03-01

    Synthetic wastewater samples containing a model surfactant were treated using two different Fenton-like advanced oxidation processes promoted by solar radiation; the photo-Fenton reaction and Co/PMS/UV processes. Comparison between the different experimental conditions was performed by means of the overall surfactant degradation achieved and by obtaining the initial rate in the first 15 min of reaction (IR{sub 15}). It was found that, for dark Fenton reaction, the maximum surfactant degradation achieved was 14% under low iron and oxidant concentration. Increasing Fenton reagents by one magnitude order, surfactant degradation achieved 63% in 60 min. The use of solar radiation improved the reaction rate by 17% under same conditions and an additional increase of 12.5% was obtained by adjusting initial pH to 2. IR{sub 15} values for dark and irradiated Fenton reactions were 0.143 and 0.154 mmol/min, respectively, for similar reaction conditions and this value increased to 0.189 mmol/min when initial pH was adjusted. The use of the Co/PMS system allow us to determine an increase in the degradation rate, for low reaction conditions (1 mM of transition metal; 4 mM oxidant) similar to those used in dark Fenton reaction. Surfactant degradation increased from 3%, for Fenton reaction, to 44.5% in the case of Co/PMS. When solar irradiation was included in the experiments, under same reaction conditions described earlier, surfactant degradation up to 64% was achieved. By increasing Co/PMS reagent concentration by almost 9 times under irradiated conditions, almost complete (>99%) surfactant degradation was reached in 5 min. Comparing IR{sub 15} values for Co/PMS and Co/PMS/UV, it allow us to observe that the use of solar radiation increased the degradation rate in one magnitude order when compared with dark experiments and further increase of reagent concentration increased reaction rate twice.

  1. Effect of Added Brine on the Physico Chemical Studies of Sodium Dodecyl Sulfate and Aqueous Gelatin

    Science.gov (United States)

    George, Jinu; Sreejith, Lisa

    2011-10-01

    Effect of added brine on the structural transitions of SDS, in different compositions of gelatin has been investigated by viscosity, circular dichroism, TGA and DSC. The slow and steady growth of the normal spherical micelles to the higher order aggregates were predicted by viscosity and conductivity measurements. The large negative value for ellipticity observed from CD measurements indicated absence of any conformational change for gelatin. Other measurements were used to study the molecular packing in the micellar aggregates. The complex formed exhibits fantastic properties to be explored in the field of smart gels.

  2. A Fourier transform infrared spectroscopic study of dodecyltrimethylammonium chloride/sodium dodecyl sulfate surfactant mixtures

    Energy Technology Data Exchange (ETDEWEB)

    Scheuing, D.R.; Weers, J.G. (Clorox Technical Center, Pleasanton, CA (USA))

    1990-03-01

    The utility of FT-IR in characterizing the composition-dependent changes in packing of DTAC and SDS in mixed micelles is demonstrated. As the mixed micelle composition becomes equimolar, the micelle aggregation number is known to increase, indicating a spherical to nonspherical micelle shape change. The frequency of the composite CH{sub 2} stretching bands decreases as the composition becomes equimolar, suggesting a decrease in the gauche/trans conformer ratio in the tails of the surfactants, which is a result of the increased crowding of the methylene chains accompanying the shape change. The use of SDS-d{sub 25} allows confirmation of this trend through the inspection of the shifts in the CH{sub 2} stretching bands (DTAC tails) and the CD{sub 2} stretching bands (SDS-d{sub 25} tails). Electrostatic interactions between the headgroups of DTAC and SDS can also be monitored spectroscopically. The shifts in the asymmetric and symmetric S-O stretching bands with micelle composition indicate an increase in SDS headgroup ordering in SDS-rich mixed micelles and a dominance of interactions with DTA{sup +} ions in DTAC-rich micelles.

  3. Microdisc gel electrophoresis in sodium dodecyl sulfate of organic material from rat otoconial complexes

    Science.gov (United States)

    Ross, M. D.; Pote, K. G.; Rarey, K. E.; Verma, L. M.

    1981-01-01

    The gravity receptors of all vertebrates utilize a 'test mass' consisting of a complex arrangement of mineral and organic substance that lies over the sensory receptor areas. In most vertebrates, the mineral is a polymorph of calcium carbonate in the form of minute, single crystals called otoconia. An investigation is conducted to determine the number of proteins in otoconial complexes and their molecular weights. The investigation makes use of a microdisk gel electrophoresis method reported by Gainer (1971). The most important finding of the reported research is that analysis of the proteins of the organic material of the otoconial complexes is possible when sensitive microanalytical methods are employed. Further modification of the basic technique employed and the inclusion of other sensitive staining methods should mean that, in the future, protein separation by molecular weight will be possible in sample pools containing only two otoconial masses.

  4. Highly sensitive fluorescent stain for detecting lipopolysaccharides in sodium dodecyl sulfate polyacrylamide gel electrophoresis.

    Science.gov (United States)

    Wang, Xu; Zhou, Ayi; Cai, Wanhui; Yu, Dongdong; Zhu, Zhongxin; Jiang, Chengxi; Jin, Litai

    2015-08-01

    A sensitive and simple technique was developed for the visualization of gel-separated lipopolysaccharides by using a hydrazide derivative, UGF202. As low as 0.5-1 ng total LPS could be detected by UGF202 stain, which is 2- and 16-fold more sensitive than that of the commonly used Pro-Q Emerald 300 and Keenan et al. developed silver stain, respectively. The results indicated that UGF202 stain could be a good choice for LPS determination in polyacrylamide gels. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Identifying changes in chemical, interfacial and foam properties of ß-lactoglobulin–sodium dodecyl sulphate mixtures

    NARCIS (Netherlands)

    Lech, F.J.; Steltenpool, P.; Meinders, M.B.J.; Sforza, S.; Gruppen, H.; Wierenga, P.A.

    2014-01-01

    Techno-functional properties of proteins, such as foam stability, can be affected by the presence of low-molecular-weight surfactants. In order to understand and control the foam properties of such protein–surfactant mixtures, a thorough characterization of foam and interfacial properties needs to b

  6. Quercetin solubilisation in bile salts: A comparison with sodium dodecyl sulphate.

    Science.gov (United States)

    Buchweitz, Maria; Kroon, Paul A; Rich, Gillian T; Wilde, Peter J

    2016-11-15

    To understand the bioaccessibility of the flavonoid quercetin we studied its interaction with bile salt micelles. The environmental sensitivity of quercetin's UV-visible absorption spectrum gave information about quercetin partitioning. Two quercetin absorption peaks gave complementary information: Peak A (240-280nm) on the intermicellar phase and Peak B (340-440nm) on the micellar phase. Thus, by altering pH, we showed that only non-ionised quercetin partitions into micelles. We validated our interpretation by studying quercetin's interaction with SDS micelles. Pyrene fluorescence and the quercetin UV-visible spectra show that the adsorption site for pyrene and quercetin in bile salt micelles is more hydrophobic than that for SDS micelles. Also, both quercetin and pyrene reported a higher critical micelle concentration for bile salts than for SDS. Our method of using a flavonoid as an intrinsic probe, is generally applicable to other lipophilic bioactives, whenever they have observable environmental dependent properties.

  7. Differentiation and distribution of colistin- and sodium dodecyl sulfate-tolerant cells in Pseudomonas aeruginosa biofilms

    DEFF Research Database (Denmark)

    Haagensen, Janus Anders Juul; Klausen, M; Ernst, RK

    2007-01-01

    biofilms, and the development of tolerance to the antimicrobial agents was found to be affected as well. Mutations in genes interfering with lipopolysaccharide modification (pmr) eliminated the biofilm-associated colistin tolerance phenotype. Experiments with a PAO1 strain harboring a pmr-gfp fusion showed...... that only the cap-forming subpopulation in biofilms treated with colistin expresses the pmr operon. These results suggest that increased antibiotic tolerance in biofilms may be a consequence of differentiation into distinct subpopulations with different phenotypic properties....

  8. Identifying changes in chemical, interfacial and foam properties of ß-lactoglobulin–sodium dodecyl sulphate mixtures

    NARCIS (Netherlands)

    Lech, F.J.; Steltenpool, P.; Meinders, M.B.J.; Sforza, S.; Gruppen, H.; Wierenga, P.A.

    2014-01-01

    Techno-functional properties of proteins, such as foam stability, can be affected by the presence of low-molecular-weight surfactants. In order to understand and control the foam properties of such protein–surfactant mixtures, a thorough characterization of foam and interfacial properties needs to

  9. Poliovirus sampling by using sodium dodecyl sulfate/EDTA-pretreated chromatography paper strips.

    Science.gov (United States)

    Maes, Piet; Van Doren, Els; Denys, Barbara; Thoelen, Inge; Rahman, Mustafizur; Vijgen, Leen; Van Ranst, Marc

    2004-12-17

    To achieve the goal of poliovirus eradication, surveillance of endemic areas is a crucial step in the poliovirus eradication program. Currently, six countries still have endemic poliovirus. We have tested a novel method which uses SDS/EDTA-treated chromatography paper strips to collect and transport poliovirus-containing stool samples. The SDS/EDTA-treated paper strips were soaked with different dilutions of poliovirus-containing feces and stored at different temperatures. After storing the SDS/EDTA paper strips for 5 months at 37 degrees C, poliovirus RNA could be successfully amplified using RT-PCR. Infectivity of wild-type poliovirus type 1, 2, and 3 was lost upon contact with the SDS/EDTA-treated strips. This easy, inexpensive, and biosafe chromatography paper strip method for the collection and transportation of poliovirus samples can be of use in poliovirus surveillance and polio vaccination programs.

  10. Inactivation of brain Na+,K(+)-ATPase catalytic subunit isoforms by sodium dodecyl sulfate.

    Science.gov (United States)

    Kaplya, A; Kravtsova, V V; Kravtsov, A V

    1997-01-01

    Persistence of the brain and kidney Na+,K(+)-ATPase isozymes to SDS inactivation under different time and temperature conditions of microsome extraction with the detergent was compared. In contrast to enzyme preparations from medulla oblongata the higher sensitivity of the Na+,K(+)-ATPase alpha-isoform (in comparison to alpha +) to SDS inactivation accompanied by its, at least, partial removal from the membrane was found in the preparations from cerebral cortex. This difference in the sensitivity to SDS was eliminated after extraction of microsomes with the detergent at 37 degrees C. The interpretation of the results is based on the assumed differences in the structural organization of the boundary lipids of the neuronal Na+,K(+)-ATPase catalytic subunit isoforms.

  11. Phase Behavior and Dielectric Spectroscopy of the Sodiun Dodecyl Trioxyethylene Sulfate/n-Butanol/Water System

    Institute of Scientific and Technical Information of China (English)

    WEI, Su-Xiang; MU, Jian-Hai; ZHAO, Kong-Shuang; LEI, Jian-Ping; LI, Gan-Zuo

    2003-01-01

    The phase diagram of the ternary system of sodium dodecyl trioxyethylene sulfate (SDES)/n-butanol/water is obtained at (30.0 ± 0.1) ℃. There exists a clear, isotropic, and low-viscosity L phase, which could be divided into W/O micelle, bicontinuous (B. C. ) phase and O/W micelle by conductivity measurements. Dielectric Relaxation Spectroscopy (DRS) measurements are applied to investigate microstructure changes of this system. For samples with a fixed weight ratio, SDES/nbutanol = 3/7, DRS indicates a structure transition from W/Oto O/W micelles via B.C. Phase with the increase of water content. For the samples with a fixed weight ratio, SDES/H2O =4/6, DRS can presents that there exist changes of onefold structure size of W/O micelles as n-butanol content increases. The results obtained from DRS and their analyses are in good agreement with those from phase diagram and conductivity measurements.

  12. [Electrochemical behavior of dopamine at dodecyl benzenesulfonate self-assembled monolayers modified electrode and its application].

    Science.gov (United States)

    Han, Xiao-xia; Gao, Zuo-ning

    2007-04-01

    Sodium dodecyl benzenesulfonate (SDBS) self-assembled monolayers in situ modified electrode (SDBS/CPE) was prepared. The electrochemical behaviors of dopamine (DA) on SDBS/CPE were studied. Electrochemical behaviors and kinetic parameters of DA were investigated at SDBS/CPE by cyclic voltammetry (CV), chronoamperometry (CA) and chronocoulometry (CC). The changes of the oxidation peak currents with concentration of DA were examined by square wave voltametry (SWV). The difference of peak potential at CPB/CPE was less than 149 mV comparing with that at CPE. The charge transfer coefficient alpha, diffusion coefficient D and the apparent reaction rate constant k(f) are 0.61, 3.6 x 10(-5) cm2 x s(-1) and 4.2 x 10(-3) cm x s(-1), respectively. The oxidation peak currents of DA versus its concentration have a good linear relationship in the concentration range of 2.0 x 10(-6)-1.0 x 10(-3) mol x L(-1) with the correlation coefficient of 0.9979 and the detection limit of 9.0 x 10(-7) mol x L(-1) by square wave voltammetry (SWV) response. The modified electrode showed an excellent electrocatalytic activity for the DA electrochemical oxidation. The method can be applied in the determination of DA in injection samples with the satisfactory results.

  13. Can A Denaturant Stabilize DNA? Pyridine Reverses DNA Denaturation in Acidic pH.

    Science.gov (United States)

    Portella, Guillem; Terrazas, Montserrat; Villegas, Núria; González, Carlos; Orozco, Modesto

    2015-09-01

    The stability of DNA is highly dependent on the properties of the surrounding solvent, such as ionic strength, pH, and the presence of denaturants and osmolytes. Addition of pyridine is known to unfold DNA by replacing π-π stacking interactions between bases, stabilizing conformations in which the nucleotides are solvent exposed. We show here experimental and theoretical evidences that pyridine can change its role and in fact stabilize the DNA under acidic conditions. NMR spectroscopy and MD simulations demonstrate that the reversal in the denaturing role of pyridine is specific, and is related to its character as pseudo groove binder. The present study sheds light on the nature of DNA stability and on the relationship between DNA and solvent, with clear biotechnological implications.

  14. Kinetically controlled refolding of a heat-denatured hyperthermostable protein

    NARCIS (Netherlands)

    Koutsopoulos, Sotirios; van der Oost, John; Norde, Willem

    2007-01-01

    The thermal denaturation of endo-beta-1,3-glucanase from the hyperthermophilic microorganism Pyrococcus furiosus was studied by calorimetry. The calorimetric profile revealed two transitions at 109 and 144 degrees C, corresponding to protein denaturation and complete unfolding, respectively, as

  15. Kinetically controlled refolding of a heat denatured hyperthermostable protein

    NARCIS (Netherlands)

    Koutsopoulos, S.; Oost, van der J.; Norde, W.

    2007-01-01

    The thermal denaturation of endo-ß-1,3-glucanase from the hyperthermophilic microorganism Pyrococcus furiosus was studied by calorimetry. The calorimetric profile revealed two transitions at 109 and 144¿°C, corresponding to protein denaturation and complete unfolding, respectively, as shown by

  16. 19 CFR 10.56 - Vegetable oils, denaturing; release.

    Science.gov (United States)

    2010-04-01

    ... 19 Customs Duties 1 2010-04-01 2010-04-01 false Vegetable oils, denaturing; release. 10.56 Section... Vegetable Oils § 10.56 Vegetable oils, denaturing; release. (a) Olive, palm-kernel, rapeseed, sunflower, and sesame oil shall be classifiable under subheadings 1509.10.20, 1509.10.40, 1509.90.20, 1509.90.40,...

  17. 27 CFR 19.464 - Denatured spirits inventories.

    Science.gov (United States)

    2010-04-01

    ... inventories. 19.464 Section 19.464 Alcohol, Tobacco Products and Firearms ALCOHOL AND TOBACCO TAX AND TRADE... of Articles Inventories § 19.464 Denatured spirits inventories. Each proprietor shall take a physical inventory of all denatured spirits in the processing account at the close of each calendar quarter and...

  18. 27 CFR 20.144 - Packages of completely denatured alcohol.

    Science.gov (United States)

    2010-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2010-04-01 2010-04-01 false Packages of completely denatured alcohol. 20.144 Section 20.144 Alcohol, Tobacco Products and Firearms ALCOHOL AND TOBACCO TAX AND TRADE BUREAU, DEPARTMENT OF THE TREASURY LIQUORS DISTRIBUTION AND USE OF DENATURED ALCOHOL AND RUM...

  19. 27 CFR 20.261 - Records of completely denatured alcohol.

    Science.gov (United States)

    2010-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2010-04-01 2010-04-01 false Records of completely denatured alcohol. 20.261 Section 20.261 Alcohol, Tobacco Products and Firearms ALCOHOL AND TOBACCO TAX AND TRADE BUREAU, DEPARTMENT OF THE TREASURY LIQUORS DISTRIBUTION AND USE OF DENATURED ALCOHOL AND...

  20. 40 CFR 721.3848 - Glycine, N-(carboxymethyl)-N-dodecyl-, monosodium salt.

    Science.gov (United States)

    2010-07-01

    ...-, monosodium salt. 721.3848 Section 721.3848 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Specific Chemical Substances § 721.3848 Glycine, N-(carboxymethyl)-N-dodecyl-, monosodium salt. (a... glycine, N-(carboxymethyl)-N-dodecyl-, monosodium salt (PMN P-00-469; CAS No. 141321-68-8) is subject to...

  1. Thermal denaturation of A-DNA

    Science.gov (United States)

    Valle-Orero, J.; Wildes, A. R.; Theodorakopoulos, N.; Cuesta-López, S.; Garden, J.-L.; Danilkin, S.; Peyrard, M.

    2014-11-01

    The DNA molecule can take various conformational forms. Investigations focus mainly on the so-called ‘B-form’, schematically drawn in the famous paper by Watson and Crick [1]. This is the usual form of DNA in a biological environment and is the only form that is stable in an aqueous environment. Other forms, however, can teach us much about DNA. They have the same nucleotide base pairs for ‘building blocks’ as B-DNA, but with different relative positions, and studying these forms gives insight into the interactions between elements under conditions far from equilibrium in the B-form. Studying the thermal denaturation is particularly interesting because it provides a direct probe of those interactions which control the growth of the fluctuations when the ‘melting’ temperature is approached. Here we report such a study on the ‘A-form’ using calorimetry and neutron scattering. We show that it can be carried further than a similar study on B-DNA, requiring the improvement of thermodynamic models for DNA.

  2. Laccase aided modification of nanofibrillated cellulose with dodecyl gallate

    Directory of Open Access Journals (Sweden)

    Päivi Saastamoinen

    2012-11-01

    Full Text Available Nanofibrillated cellulose, NFC, is an interesting wood fibre-based material that could be utilized in coatings, foams, composites, packages, dispersions, and emulsions, due to its high tensile strength and barrier properties, light weight, and stabilizing features. To improve applicability and properties of NFC, modification of its surface properties is often needed. In this study, the applicability of laccase-aided surface modification with hydrophobic dodecyl gallate (DOGA on unbleached NFC was investigated. Also, laccase-catalyzed polymerization of DOGA and other phenolic compounds with lignin moieties was investigated by matrix-assisted laser desorption/ionization time-of-flight mass spectroscopy (MALDI-TOF MS. NFC modified with T. hirsuta-based laccase and DOGA showed decreased hydrophilicity, as compared with the native NFC, when coated on a paper surface. When dried as free-standing films, the surface properties of chemo-enzymatically modified NFC resembled those of the native NFC. The effect of modification was thus greatly influenced by different surface formation in differently prepared samples. Also, changing of the dispersion properties of DOGA by enzymatic polymerization affected the surface properties of the dried NFC samples. Covalent bonding between DOGA and NFC was not the main factor affecting the surface properties of the NFC in free-standing films or coatings.

  3. Microwave-enhanced folding and denaturation of globular proteins

    DEFF Research Database (Denmark)

    Bohr, Henrik; Bohr, Jakob

    2000-01-01

    It is shown that microwave irradiation can affect the kinetics of the folding process of some globular proteins, especially beta-lactoglobulin. At low temperature the folding from the cold denatured phase of the protein is enhanced, while at a higher temperature the denaturation of the protein from...... its folded state is enhanced. In the latter case, a negative temperature gradient is needed for the denaturation process, suggesting that the effects of the microwaves are nonthermal. This supports the notion that coherent topological excitations can exist in proteins. The application of microwaves...

  4. Lyophilization-induced protein denaturation in phosphate buffer systems: monomeric and tetrameric beta-galactosidase.

    Science.gov (United States)

    Pikal-Cleland, K A; Carpenter, J F

    2001-09-01

    During freezing in phosphate buffers, selective precipitation of a less soluble buffer component and subsequent pH shifts may induce protein denaturation. Previous reports indicate significantly more inactivation and secondary structural perturbation of monomeric and tetrameric beta-galactosidase (beta-gal) during freeze-thawing in sodium phosphate (NaP) buffer as compared with potassium phosphate (KP) buffer. This observation was attributed to the significant pH shifts (from 7.0 to as low as 3.8) observed during freezing in the NaP buffer (1). In the current study, we investigated the impact of the additional stress of dehydration after freezing on the recovery of active protein on reconstitution and the retention of the native structure in the dried state. Freeze-drying monomeric and tetrameric beta-gal in either NaP or KP buffer resulted in significant secondary structural perturbations, which were greatest for the NaP samples. However, similar recoveries of active monomeric protein were observed after freeze-thawing and freeze-drying, indicating that most dehydration-induced unfolding was reversible on reconstitution of the freeze-dried protein. In contrast, the tetrameric protein was more susceptible to dehydration-induced denaturation as seen by the greater loss in activity after reconstitution of the freeze-dried samples relative to that measured after freeze-thawing. To ensure optimal protein stability during freeze-drying, the protein must be protected from both freezing and dehydration stresses. Although poly(ethylene glycol) and dextran are preferentially excluded solutes and should confer protection during freezing, they were unable to prevent lyophilization-induced denaturation. In addition, Tween did not foster maintenance of native protein during freeze-drying. However, sucrose, which hydrogen bonds to dried protein in the place of lost water, greatly reduced freezing- and drying-induced denaturation, as observed by the high retention of native

  5. Statistical mechanics of thermal denaturation of DNA oligomers

    Indian Academy of Sciences (India)

    Navin Singh; Yashwant Singh

    2003-08-01

    Double stranded DNA chain is known to have non-trivial elasticity. We study the effect of this elasticity on the denaturation profile of DNA oligomer by constraining one base pair at one end of the oligomer to remain in unstretched (or intact) state. The effect of this constraint on the denaturation profile of the oligomer has been calculated using the Peyrard–Bishop Hamiltonian. The denaturation profile is found to be very different from the free (i.e. without the constraint) oligomer. We have also examined how this constraint affects the denaturation profile of the oligomer having a segment of defect sites located at different parts of the chain.

  6. Sodium Test

    Science.gov (United States)

    ... low levels of cortisol, aldosterone and sex hormones ( Addison disease ) Drinking too much water as might occur during ... urinary sodium levels may indicate diuretic use or Addison disease. Sodium levels are often evaluated in relation to ...

  7. Sodium Phosphate

    Science.gov (United States)

    Sodium phosphate is used in adults 18 years of age or older to empty the colon (large intestine, bowel) ... view of the walls of the colon. Sodium phosphate is in a class of medications called saline ...

  8. Sodium Oxybate

    Science.gov (United States)

    Sodium oxybate is used to prevent attacks of cataplexy (episodes of muscle weakness that begin suddenly and ... urge to sleep during daily activities, and cataplexy). Sodium oxybate is in a class of medications called ...

  9. Thermal denaturation of type I collagen vitrified gels

    Energy Technology Data Exchange (ETDEWEB)

    Xia, Zhiyong, E-mail: zhiyong.xia@jhuapl.edu [The Johns Hopkins University, Applied Physics Laboratory, Laurel, MD 20723 (United States); Calderon-Colon, Xiomara [The Johns Hopkins University, Applied Physics Laboratory, Laurel, MD 20723 (United States); Trexler, Morgana, E-mail: morgana.trexler@jhuapl.edu [The Johns Hopkins University, Applied Physics Laboratory, Laurel, MD 20723 (United States); Elisseeff, Jennifer; Guo, Qiongyu [The Johns Hopkins University, Department of Biomedical Engineering, Baltimore, MD 21231 (United States)

    2012-01-10

    Highlights: Black-Right-Pointing-Pointer We analyzed the denaturation of vitrigels synthesized under different conditions. Black-Right-Pointing-Pointer Overall denaturation kinetics consisted of both reversible and irreversible steps. Black-Right-Pointing-Pointer More stable vitrigels were formed under high level of vitrification. - Abstract: The denaturation kinetics of type I collagen vitrigels synthesized under different vitrification time and temperature were analyzed by the classical Kissinger approach and the advanced model free kinetics (AMFK) using the Vyazovkin algorithm. The AMFK successfully elucidated the overall denaturation into reversible and irreversible processes. Depending on vitrification conditions, the activation energy for the irreversible process ranged from 100 to 200 kJ/mol, and the reversible enthalpy ranged from 250 to 300 kJ/mol. All of these values increased with the vitrification time and temperature, indicating that a more stable and complex structure formed with increased vitrification. The classical Kissinger method predicted the presence of a critical temperate of approximately 60 Degree-Sign C for the transition between reversible and irreversible processes. Scanning electron microscopy revealed the presence of fibril structures in vitrigels both before and after full denaturation; however the fibrils had became thicker and rougher after denaturation.

  10. Preparation and characterization of n-dodecyl-ferulate-loaded solid lipid nanoparticles (SLN).

    Science.gov (United States)

    Souto, E B; Anselmi, C; Centini, M; Müller, R H

    2005-05-13

    Solid lipid nanoparticles (SLN) containing a novel potential sunscreen n-dodecyl-ferulate (ester of ferulic acid) were developed. The preparation and stability parameters of n-dodecyl-ferulate-loaded SLN have been investigated concerning particle size, surface electrical charge (zeta potential) and matrix crystallinity. The chemical stability of n-dodecyl-ferulate at high temperatures was also assessed by thermal gravimetry analysis. For the selection of the appropriated lipid matrix, chemically different lipids were melted with 4% (m/m) of active and lipid nanoparticles were prepared by the so-called high pressure homogenization technique. n-Dodecyl-ferulate-loaded SLN prepared with cetyl palmitate showed the lowest mean particle size and polydispersity index, as well as the highest physical stability during storage time of 21 days at 4, 20 and 40 degrees C. These colloidal dispersions containing the sunscreen also exhibited the common melting behaviour of aqueous SLN dispersions.

  11. 27 CFR 19.57 - Recovery and reuse of denatured spirits in manufacturing processes.

    Science.gov (United States)

    2010-04-01

    ... denatured spirits in manufacturing processes. 19.57 Section 19.57 Alcohol, Tobacco Products and Firearms... denatured spirits in manufacturing processes. The following persons are not, by reason of the activities...) Manufacturers who use denatured spirits, or articles or substances containing denatured spirits, in a process...

  12. Dodine as a transparent protein denaturant for circular dichroism and infrared studies.

    Science.gov (United States)

    Guin, Drishti; Sye, Kori; Dave, Kapil; Gruebele, Martin

    2016-05-01

    The fungicide dodine combines the cooperative denaturation properties of guanidine with the mM denaturation activity of SDS. It was previously tested only on two small model proteins. Here we show that it can be used as a chemical denaturant for phosphoglycerate kinase (PGK), a much larger two-domain enzyme. In addition to its properties as a chemical denaturant, dodine facilitates thermal denaturation of PGK, and we show for the first time that it also facilitates pressure denaturation of a protein. Much higher quality circular dichroism and amide I' infrared spectra of PGK can be obtained in dodine than in guanidine, opening the possibility for use of dodine as a denaturant when UV or IR detection is desirable. One caution is that dodine denaturation, like other detergent-based denaturants, is less reversible than guanidine denaturation. © 2016 The Protein Society.

  13. Sodium and Food Sources

    Science.gov (United States)

    ... Sources Top 10 Sources of Sodium How to Reduce Sodium Sodium Reduction Resources for Everyone Sodium Reduction Fact ... in processed food [PDF-867K] and how to reduce sodium. Sodium Reduction Is Challenging Types of food matter: ...

  14. Sodium in diet

    Science.gov (United States)

    Diet - sodium (salt); Hyponatremia - sodium in diet; Hypernatremia - sodium in diet; Heart failure - sodium in diet ... The body uses sodium to control blood pressure and blood volume. Your body also needs sodium for your muscles and nerves to work ...

  15. Unusual cold denaturation of a small protein domain.

    Science.gov (United States)

    Buchner, Ginka S; Shih, Natalie; Reece, Amy E; Niebling, Stephan; Kubelka, Jan

    2012-08-21

    A thermal unfolding study of the 45-residue α-helical domain UBA(2) using circular dichroism is presented. The protein is highly thermostable and exhibits a clear cold unfolding transition with the onset near 290 K without denaturant. Cold denaturation in proteins is rarely observed in general and is quite unique among small helical protein domains. The cold unfolding was further investigated in urea solutions, and a simple thermodynamic model was used to fit all thermal and urea unfolding data. The resulting thermodynamic parameters are compared to those of other small protein domains. Possible origins of the unusual cold unfolding of UBA(2) are discussed.

  16. OBSERVATION OF DNA PARTIAL DENATURATION BY ATOMIC FORCE MICROSCOPY

    Institute of Scientific and Technical Information of China (English)

    Xin-hua Dai; Zhi-gang Wang; Bo Xiao; Yong-jun Zhang; Chen Wang; Chun-li Bai; Xiao-li Zhang; Jian Xu

    2004-01-01

    Atomic force microscopy was used to investigate the DNA-cetyltrimethylammonium bromide (CTAB) complexes adsorbed on highly ordered pyrolytic graphite (HOPG). These complexes, at low concentrations, can automatically spread out on the surface of HOPG. The DNA-CTAB complexes display a typically extended structure rather than a globular structure. Partially denaturated DNA produced by binding CTAB to DNA is directly observed by AFM with high resolution.The three-dimensional resolution of partially denaturated DNA obtained by AFM is not available by any other technique at present.

  17. Single-molecule denaturation mapping of DNA in nanofluidic channels

    DEFF Research Database (Denmark)

    Reisner, Walter; Larsen, Niels Bent; Silahtaroglu, Asli

    2010-01-01

    Here we explore the potential power of denaturation mapping as a single-molecule technique. By partially denaturing YOYO (R)-1-labeled DNA in nanofluidic channels with a combination of formamide and local heating, we obtain a sequence-dependent "barcode" corresponding to a series of local dips....... Consequently, the technique is sensitive to sequence variation without requiring enzymatic labeling or a restriction step. This technique may serve as the basis for a new mapping technology ideally suited for investigating the long-range structure of entire genomes extracted from single cells....

  18. MICRO-DETERMINATION OF DODECYL DIMETHYL BENZYL-AMMONIUM CHLOR IDE%微量十二烷基二甲基苯甲基氯化铵的测定

    Institute of Scientific and Technical Information of China (English)

    俞斌; 王峰; 栾承莲

    2001-01-01

    十二烷基二甲基苯甲基氯化铵、十二烷基磺酸钠和溴百里酚蓝在pH 7.4~8.2范围内形成黄绿色离子缔合物。把十二烷基磺酸钠、溴百里酚蓝、缓冲溶液按顺序加入十二烷基二甲基苯甲基氯化铵中,15 min后于456 nm处测其吸光度,微量测定十二烷基二甲基苯甲基氯化铵的含量。通过调节pH值、加入掩蔽剂掩蔽金属离子排除干扰。%Dodecyl dimethyl benzyl-ammonium chloride, sodium laurylsulfonate and bromothymol blue can form yellowish blue ion association complex in pH 7.4~8.2, affi x sodium laurylsulfonate, bromothymol blue and buffer solution to dodecyl dimeth yl benzyl-ammonium chloride in normal sequence. Record the absorbance data of so lutio n in 456nm with spectrophotometer, micro-determine the content of dodecyl di methyl benzyl-ammonium chloride. The disturbance was removed by adjusting the pH value and adding the screening agent to mask the metalion.

  19. Hidden Sodium

    Centers for Disease Control (CDC) Podcasts

    2013-03-04

    In this podcast, learn about reducing sodium intake by knowing what to eat and the main sources of sodium in the diet. It's important for a healthy lifestyle.  Created: 3/4/2013 by National Center for Chronic Disease Prevention and Health Promotion (NCCDPHP).   Date Released: 3/4/2013.

  20. Dietary sodium

    DEFF Research Database (Denmark)

    Graudal, Niels

    2015-01-01

    The 2013 Institute of Medicine (IOM) report "Sodium Intake in Populations: Assessment of Evidence" did not support the current recommendations of the IOM and the American Heart Association (AHA) to reduce daily dietary sodium intake to below 2,300 mg. The report concluded that the population...... Control (CDC), other public health advisory bodies, and major medical journals have continued to support the current policy of reducing dietary sodium.......-based health outcome evidence was not sufficient to define a safe upper intake level for sodium. Recent studies have extended this conclusion to show that a sodium intake below 2,300 mg/day is associated with increased mortality. In spite of this increasing body of evidence, the AHA, Centers for Disease...

  1. Denaturation of membrane proteins and hyperthermic cell killing

    NARCIS (Netherlands)

    Burgman, Paulus Wilhelmus Johannes Jozef

    1993-01-01

    Summarizing: heat induced denaturation of membrane proteins is probably related to hyperthermic cell killing. Induced resistance of heat sensitive proteins seems to be involved in the development of thermotolerance. Although many questions remain still to be answered, it appears that HSP72, when

  2. Thermal and chemical unfolding and refolding of a eukaryotic sodium channel.

    Science.gov (United States)

    Charalambous, Kalypso; O'Reilly, A O; Bullough, Per A; Wallace, B A

    2009-06-01

    Voltage-gated sodium channels are dynamic membrane proteins essential for signaling in nervous and muscular systems. They undergo substantial conformational changes associated with the closed, open and inactivated states. However, little information is available regarding their conformational stability. In this study circular dichroism spectroscopy was used to investigate the changes in secondary structure accompanying chemical and thermal denaturation of detergent-solubilised sodium channels isolated from Electrophorus electricus electroplax. The proteins appear to be remarkably resistant to either type of treatment, with "denatured" channels, retaining significant helical secondary structure even at 77 degrees C or in 10% SDS. Further retention of helical secondary structure at high temperature was observed in the presence of the channel-blocking tetrodotoxin. It was possible to refold the thermally-denatured (but not chemically-denatured) channels in vitro. The correctly refolded channels were capable of undergoing the toxin-induced conformational change indicative of ligand binding. In addition, flux measurements in liposomes showed that the thermally-denatured (but not chemically-denatured) proteins were able to re-adopt native, active conformations. These studies suggest that whilst sodium channels must be sufficiently flexible to undergo major conformational changes during their functional cycle, the proteins are highly resistant to unfolding, a feature that is important for maintaining structural integrity during dynamic processes.

  3. Urea Induced Denaturation of Pre-Q1 Riboswitch

    Science.gov (United States)

    Yoon, Jeseong; Thirumalai, Devarajan; Hyeon, Changbong

    2013-01-01

    Urea, a polar molecule with a large dipole moment, not only destabilizes the folded RNA structures, but can also enhance the folding rates of large ribozymes. Unlike the mechanism of urea-induced unfolding of proteins, which is well understood, the action of urea on RNA has barely been explored. We performed extensive all atom molecular dynamics (MD) simulations to determine the molecular underpinnings of urea-induced RNA denaturation. Urea displays its denaturing power in both secondary and tertiary motifs of the riboswitch (RS) structure. Our simulations reveal that the denaturation of RNA structures is mainly driven by the hydrogen bonds and stacking interactions of urea with the bases. Through detailed studies of the simulation trajectories, we found that geminate pairs between urea and bases due to hydrogen bonds and stacks persist only ~ (0.1-1) ns, which suggests that urea-base interaction is highly dynamic. Most importantly, the early stage of base pair disruption is triggered by penetration of water molecules into the hydrophobic domain between the RNA bases. The infiltration of water into the narrow space between base pairs is critical in increasing the accessibility of urea to transiently disrupted bases, thus allowing urea to displace inter base hydrogen bonds. This mechanism, water-induced disruption of base-pairs resulting in the formation of a "wet" destabilized RNA followed by solvation by urea, is the exact opposite of the two-stage denaturation of proteins by urea. In the latter case, initial urea penetration creates a dry-globule, which is subsequently solvated by water penetration leading to global protein unfolding. Our work shows that the ability to interact with both water and polar, non-polar components of nucleotides makes urea a powerful chemical denaturant for nucleic acids.

  4. Viscosity measurements of CO2-in-water foam with dodecyl polypropoxy sulfate surfactants for enhanced oil recovery application

    Science.gov (United States)

    Pramudita, Ria Ayu; Ryoo, Won Sun

    2016-08-01

    Apparent viscosities of CO2-in-water foams were measured in a wide range of shear rate from 50 to 105 inverse second for enhanced oil recovery (EOR) application. The CO2-in-water dispersions, made of 50:50 weight proportions of CO2 and water with 1 wt.% surfactant concentration, were prepared in high-pressure recirculation apparatus under pressure where CO2 density becomes 0.7, 0.8, and 0.9 g/mL at each temperature of 35, 45, and 55°C. The surfactants used for the foam generation were sodium dodecyl polypropoxy sulfates with average propoxylation degrees of 4.7 and 6.2. The foam viscosity showed shear thinning behaviors with power-law indices ranging from 0.80 to 0.85, and approached a Newtonian regime in the lower shear rate range at several tens of inverse second. Zero-shear viscosity values projected from experimental data based on Ellis model were as high as 57.4 mPa·s and enough to control the mobility of water and CO2 in oil reservoirs.

  5. Denaturing and non-denaturing gel electrophoresis as methods for the detection ofjunctional diversity in rearranged T cell receptor sequences

    NARCIS (Netherlands)

    Offermans, M.T.C.; Sonneveld, R.D.; Bakker, E.; Deutz-Terlouw, P.P.; Geus, B. de; Rozing, J.

    1995-01-01

    Two nucleic acid gel electrophoresis techniques were tested as a possible tool for analyzing junctional diversity in rearranged T cell receptor (TcR) sequences in order to define the extent of T cell heterogeneity. For this purpose denaturing gradient gel electrophoresis (DGGE) as well as

  6. Sodium - blood

    Science.gov (United States)

    ... gland problems such as Cushing syndrome or hyperaldosteronism Diabetes insipidus (type of diabetes in which kidneys are not able to conserve water) Too much salt or sodium bicarbonate in the diet Use of certain medicines, including corticosteroids, laxatives, lithium, ...

  7. Theoretical Study on Effects of Salt and Temperature on Denaturation Transition of Double-stranded DNA

    Institute of Scientific and Technical Information of China (English)

    DONG Rui-Xin; YAN Xun-Ling; PANG Xiao-Feng; JIANG Shan; LIU Sheng-Gang

    2004-01-01

    We investigate the statistical mechanics properties of a nonlinear dynamics model of the denaturation of the DNA double-helix and study the effects of salt concentration and temperature on denaturation transition of DNA. The specific heat, entropy, and denaturation temperature of the system versus salt concentration are obtained. These results show that the denaturation of DNA not only depends on the temperature but also is influenced by the salt concentration in the solution of DNA, which are in agreement with experimental measurement.

  8. Rheological properties of sweet potato starch before and after denaturalization

    Institute of Scientific and Technical Information of China (English)

    肖华西; 林亲录; 夏新剑; 李丽辉; 林利忠; 吴卫国

    2008-01-01

    Based on the sweet potato starch,cationic starch,acetic starch and cationic-acetic compoundedly modified starch were made through chemical denaturalization.The above three kinds of static rheological parameter and dynamic rheological parameter were measured,respectively.The experimental result reveals that the thermal stability of starchy viscosity increases after chemical denaturalization.Under the condition of identical shearing rate,the shear stress of cationic-acetic ester compoundedly modified sweet potato starch paste is the largest among these kinds of sweet potato starch.This attributes to a phenomenon of shearing thinning.Furthermore,raw sweet potato starch has a larger gel intensity than that of modified starch.

  9. How water contributes to pressure and cold denaturation of proteins

    CERN Document Server

    Bianco, Valentino

    2015-01-01

    The mechanisms of cold- and pressure-denaturation of proteins are matter of debate and are commonly understood as due to water-mediated interactions. Here we study several cases of proteins, with or without a unique native state, with or without hydrophilic residues, by means of a coarse-grain protein model in explicit solvent. We show, using Monte Carlo simulations, that taking into account how water at the protein interface changes its hydrogen bond properties and its density fluctuations is enough to predict protein stability regions with elliptic shapes in the temperature-pressure plane, consistent with previous theories. Our results clearly identify the different mechanisms with which water participates to denaturation and open the perspective to develop advanced computational design tools for protein engineering.

  10. Influence of Ficoll on urea induced denaturation of fibrinogen

    Science.gov (United States)

    Sankaranarayanan, Kamatchi; Meenakshisundaram, N.

    2016-03-01

    Ficoll is a neutral, highly branched polymer used as a molecular crowder in the study of proteins. Ficoll is also part of Ficoll-Paque used in biology laboratories to separate blood to its components (erythrocytes, leukocytes etc.,). Role of Ficoll in the urea induced denaturation of protein Fibrinogen (Fg) has been analyzed using fluorescence, circular dichroism, molecular docking and interfacial studies. Fluorescence studies show that Ficoll prevents quenching of Fg in the presence of urea. From the circular dichroism spectra, Fg shows conformational transition to random coil with urea of 6 M concentration. Ficoll helps to shift this denaturation concentration to 8 M and thus constraints by shielding Fg during the process. Molecular docking studies indicate that Ficoll interacts favorably with the protein than urea. The surface tension and shear viscosity analysis shows clearly that the protein is shielded by Ficoll.

  11. Detection of activity and mass spectrometric identification of mouse liver carboxylesterase and aldehyde dehydrogenase separated by non-denaturing two-dimensional electrophoresis after extraction with detergents.

    Science.gov (United States)

    Shimazaki, Youji; Manabe, Takashi

    2005-05-20

    To examine the activities and identity of enzymes associated with organelles such as microsomes and mitochondria, proteins from mouse liver were extracted using the non-ionic detergents Nonidet P-40 (NP-40), polyoxyethylene sorbitan monooleate (Tween 80), polyoxyethylene isooctylphenyl ester (Triton X), n-octyl beta-D-glucoside (octyl glycoside) or anionic detergent sodium dodecylsulfate (SDS) after the removal of cytosolic proteins. The proteins extracted by detergents were separated by non-denaturing two-dimensional electrophoresis (2-DE). The activities of esterase and aldehyde dehydrogenase were retained by non-denaturing 2-DE after treatment with each non-ionic detergent, but the activities were reduced or lost when the proteins were extracted with more than 0.5% SDS. For proteomic analysis of the organelle-associated proteins in mouse liver, proteins were separated by non-denaturing 2-DE and were identified using electrospray ionization tandem mass spectrometry (ESI-MS/MS) after the proteins were solubilized by octyl glycoside, NP-40 and 0.1% SDS. Several organelle-associated proteins such as carboxylesterase, aldehyde dehydrogenase, glucose regulated protein and HSP60 were identified. These results indicate that the activities and identity of detergent-soluble enzymes can be examined by this non-denaturing 2-DE and mass spectrometry.

  12. Preservasi Semen Kambing Peranakan Etawa dalam Pengencer Tris dan Sitrat Kuning Telur dengan Penambahan Sodium Dodecyl Sulphate (THE PRESERVATION OF ETTAWA GRADE BUCK SEMEN IN TRIS AND CITRATE EGG YOLK DILUENTS SUPPLEMENTED WITH SODIUM DODECYL SULPHATE

    Directory of Open Access Journals (Sweden)

    Nur Hidayati

    2015-10-01

    Full Text Available This study was conducted to determineSDS concentration also to compare Tris egg yolk and citrateegg yolk on the quality of ettawa grade chilled semen. The study consist of two experiments. The firstexperiment was to determine the best SDS concentration in Tris egg yolk diluents and the second experimentwas to compare the SDS suplementation in tris and citrate egg yolk in the quality of ettawa grade chilledsemen. The semen were collected from three bucks, immediately after collection the semen evalutedmacro and microscopycally. Semen demonstrate more than 70% motility and less than 10% spermatozoaabnormality, individually divided into four tube, each tube was diluted in egg yolk supplemented with 0;0,025; 0,05; and 0.075% SDS then stored at 5°C for 72 hours. The quality of chilled semen was observefor motility and viability every 12 hours. Result demonstrated that 0.05% SDS was the best concentrationcompared to others. In the second experiment,the semen were diluted in four different diluents, it wereTris egg yolk (TEY, Tris egg yolk with 0.05% SDS (TEYS, citrate egg yolk (CEY and citrate egg yolk with0.05% SDS (CEYS. Result demonstrated that the mean value of motility and viability of spermatozoa inTEYSdiluents (67.08 ± 6.43% and77.07 ± 6.78% was higher (p<0.05 than CEYS (60.42 ± 9.05% and72.31± 7.45%, TEY (59.23 ± 9.41% and71.21 ± 8.56% and CEY (53.45 ± 11.33% and67.74 ± 8.90%. In conclusion,supplementation of 0.05% SDS in TEY was maintained best sperm quality compared to other diluentsduring preservation.

  13. Directed 2-dimensional organisation of collagen: Role of cross-linking and denaturing agents

    Indian Academy of Sciences (India)

    Nishtar nishad Fathima; Aruna Dhathathreyan; Thirumalachari Ramasami

    2010-11-01

    The effect of additives like curcumin and surfactants on the self-assembly of collagen from a simple 2-dimensional system of Langmuir films of the protein at air/solution interface has been attempted in this study using quartz crystal microbalance (QCM) and dynamic surface tensiometer. Though pure curcumin is not surface active, a synergistic effect of collagen with curcumin seems to lead to enhanced surface activity in the protein. In general, the presence of additives, increases the surface activity of collagen even for the lowest concentration and the largest change in surface activity is seen for collagen with sodium dodecyl sulfate (SDS). The results suggest interplay between the unexposed hydrophobic groups, and the opening out and solvation of the more charged or polar groups at the surface leading to aggregation followed by self-assembly. Modulation of aggregation at interface in collagen due to these additives may be an approach that could be explored for possible applications in bio-materials and for delivery of protein-drug complexes.

  14. Temperature induced denaturation of collagen in acidic solution.

    Science.gov (United States)

    Mu, Changdao; Li, Defu; Lin, Wei; Ding, Yanwei; Zhang, Guangzhao

    2007-07-01

    The denaturation of collagen solution in acetic acid has been investigated by using ultra-sensitive differential scanning calorimetry (US-DSC), circular dichroism (CD), and laser light scattering (LLS). US-DSC measurements reveal that the collagen exhibits a bimodal transition, i.e., there exists a shoulder transition before the major transition. Such a shoulder transition can recover from a cooling when the collagen is heated to a temperature below 35 degrees C. However, when the heating temperature is above 37 degrees C, both the shoulder and major transitions are irreversible. CD measurements demonstrate the content of triple helix slowly decreases with temperature at a temperature below 35 degrees C, but it drastically decreases at a higher temperature. Our experiments suggest that the shoulder transition and major transition arise from the defibrillation and denaturation of collagen, respectively. LLS measurements show the average hydrodynamic radius R(h), radius of gyration R(g)of the collagen gradually decrease before a sharp decrease at a higher temperature. Meanwhile, the ratio R(g)/R(h) gradually increases at a temperature below approximately 34 degrees C and drastically increases in the range 34-40 degrees C, further indicating the defibrillation of collagen before the denaturation.

  15. Protein's native state stability in a chemically induced denaturation mechanism.

    Science.gov (United States)

    Olivares-Quiroz, L; Garcia-Colin, L S

    2007-05-21

    In this work, we present a generalization of Zwanzig's protein unfolding analysis [Zwanzig, R., 1997. Two-state models of protein folding kinetics. Proc. Natl Acad. Sci. USA 94, 148-150; Zwanzig, R., 1995. Simple model of protein folding kinetics. Proc. Natl Acad. Sci. USA 92, 9801], in order to calculate the free energy change Delta(N)(D)F between the protein's native state N and its unfolded state D in a chemically induced denaturation. This Extended Zwanzig Model (EZM) is both based on an equilibrium statistical mechanics approach and the inclusion of experimental denaturation curves. It enables us to construct a suitable partition function Z and to derive an analytical formula for Delta(N)(D)F in terms of the number K of residues of the macromolecule, the average number nu of accessible states for each single amino acid and the concentration C(1/2) where the midpoint of the ND transition occurs. The results of the EZM for proteins where chemical denaturation follows a sigmoidal-type profile, as it occurs for the case of the T70N human variant of lysozyme (PDB code: T70N) [Esposito, G., et al., 2003. J. Biol. Chem. 278, 25910-25918], can be splitted into two lines. First, EZM shows that for sigmoidal denaturation profiles, the internal degrees of freedom of the chain play an outstanding role in the stability of the native state. On the other hand, that under certain conditions DeltaF can be written as a quadratic polynomial on concentration C(1/2), i.e., DeltaF approximately aC(1/2)(2)+bC(1/2)+c, where a,b,c are constant coefficients directly linked to protein's size K and the averaged number of non-native conformations nu. Such functional form for DeltaF has been widely known to fit experimental measures in chemically induced protein denaturation [Yagi, M., et al., 2003. J. Biol. Chem. 278, 47009-47015; Asgeirsson, B., Guojonsdottir, K., 2006. Biochim. Biophys. Acta 1764, 190-198; Sharma, S., et al., 2006. Protein Pept. Lett. 13(4), 323-329; Salem, M., et al

  16. 十二烷基苯磺酸木薯淀粉酯微波法制备工艺研究%Preparation technology of dodecyl benzene sulfonic acid cassava starch ester by microwave

    Institute of Scientific and Technical Information of China (English)

    张利伟; 薛行华; 赵法敏; 张永强; 李光

    2013-01-01

    Dodecyl benzene sulfonic acid cassava starch ester was prepared by microwave method with cassava starch as the raw material , sodium dodecyl benzene sulfonate as the esterification agent and sodium hydroxide as the catalyst .The effects of synthetic condition , such as molar ratio ( sodi-um dodecyl benzene sulfonate to glucose unit of cassava starch ) , reaction time , incubated tempera-ture and pH value , on the substitution degree were investigated .The best conditions by orthogonal design were the molar ratio of sodium dodecyl benzene sulfonate to cassava at 0.06 , reaction time 5 h and the incubated temperature 80 ℃, at which the degree of substitution was 0.010 0 .FT-IR and XRD revealed the changes in the structure of the esterified starch , and TG analysis also dis-played the decline of the hydrophilic and thermal stability of the esterified starch .%  以木薯淀粉为原料,十二烷基苯磺酸钠为酯化剂,NaOH为催化剂,采用微波法制备十二烷基苯磺酸木薯淀粉酯,并考察其合成的工艺条件。探讨了十二烷基苯磺酸钠与木薯淀粉葡萄糖单元的摩尔比、反应时间、反应温度和pH值对产物取代度的影响,用正交实验分析对制备工艺进行优化,并通过红外、X射线和热重分析表征了酯化淀粉的结构及其热稳定性。结果表明,在十二烷基苯磺酸钠与木薯淀粉葡萄糖单元摩尔比为0.06、反应时间5 h、反应温度80℃和pH为10的条件下制备的十二烷基苯磺酸酯淀粉的取代度最佳,取代度为0.0100。红外和X射线谱图证明了酯化淀粉结构的改变,热重分析表明酯化淀粉亲水性与热稳定性有所下降。

  17. Investigation and Comparison of Leishmania major Promastigote and Amastigote Protein Content by Sodium Dodecyl Sulfate Polyacrylamide Gel Electrophoresis

    Directory of Open Access Journals (Sweden)

    S. Soleimanifard

    2013-04-01

    Full Text Available ntroduction & Objective: Leishmania is a protozoan of the trypanosomatidae family. This pro-tozoan has two stages in its life cycle, promastigote form in sand flies and amastigote form in macrophage of mammalian hosts. The purpose of this study was identification and compari-son of proteins of Leishmania amastigote and promastigote stages. Materials & Methods: The present study is a cross sectional study of two forms of Leishmania major. To culture promastigotes , L.major (MRHO/IR/75/ER from previously infected Balb/c mice was transferred to modified N.N.N medium with overlay of liquid BHI and then transferred to RPMI-1640 at 26oc ± 1 for mass production. After isolation and growth, pro-mastigotes were transferred to liquid cell culture medium RPMI-1640 with pH 5.5 and incu-bated at 5% CO2 at 37oc for 72 hours until promastigote to amastigote transformation. Elec-trophoresis was performed with SDS-PAGE method to find and compare the molecular weight of the antigens of two stages. Results: The molecular weights of the bands observed in both forms were as follows: 19, 36, 50, 63, 65, 80, 90, 94, 96, 110- 130 KDa. The proteins in the surface of only promastigote were 22, 28 and 46 KDa and special proteins in the surface of amastigote were 12 and 32 KDa. Conclusion : According to this study Leishmania parasite has stage specific proteins. Various studies have shown that axenic amastigotes and tissue amastigotes are similar in their protein content. Therefore, based on stage specific proteins ,effective drugs and vaccines can be de-signed against leishmaniasis. (Sci J Hamadan Univ Med Sci 2013; 20 (1:1-8

  18. Aggregation properties of levofloxacin in water and ethanol and its interaction with sodium dodecyl sulphate: A thermodynamic study

    Indian Academy of Sciences (India)

    Muhammad Shakeel; Khalid Mehmood; Mohammad Siddiq

    2015-11-01

    This manuscript reports the determination of critical micelle concentration (CMC) of levofloxacin (LF) in two solvents, water and ethanol, by using surface tension, refractive index and absorbance measurements. The data thus obtained were used to calculate different thermodynamic parameters for micellization process like free energy of micellization, free energy of adsorption, entropy and enthalpy of micellization. The interaction of this drug with anionic surfactant (SDS) was also studied using UV/Visible spectroscopy and conductometry. With rise in temperature, CMC of the drug was found to decrease in ethanol and increase in aqueous solution indicating dominance of lipophobic desolvation over lipophilic desolvation in ethanol and reverse, in case of aqueous solution. A strong drug/surfactant interaction was found to exist. The data obtained from drug/surfactant interaction were also used to find different interaction parameters like partition constant, free energy of partition, binding constant and free energy of binding which are very useful to understand the phenomenon of solubilization.

  19. Combined alcian blue and silver staining of subnanogram quantities of proteoglycans and glycosaminoglycans in sodium dodecyl sulfate-polyacrylamide gels

    DEFF Research Database (Denmark)

    Møller, H J; Heinegård, D; Poulsen, J H

    1993-01-01

    Proteoglycans stain weakly in polyacrylamide gels by traditional protein stains such as coomassie brilliant blue or silver. In the present work preparations of large aggregating proteoglycan from human articular cartilage were used to evaluate a convenient staining method based on successive stai...

  20. Collagen thermal denaturation study for thermal angioplasty based on modified kinetic model: relation between the artery mechanical properties and collagen denaturation rate

    Science.gov (United States)

    Shimazaki, N.; Hayashi, T.; Kunio, M.; Arai, T.

    2010-02-01

    We have been developing the novel short-term heating angioplasty in which sufficient artery lumen-dilatation was attained with thermal softening of collagen fiber in artery wall. In the present study, we investigated on the relation between the mechanical properties of heated artery and thermal denaturation fractures of arterial collagen in ex vivo. We employed Lumry-Eyring model to estimate temperature- and time-dependent thermal denaturation fractures of arterial collagen fiber during heating. We made a kinetic model of arterial collagen thermal denaturation by adjustment of K and k in this model, those were the equilibrium constant of reversible denaturation and the rate constant of irreversible denaturation. Meanwhile we demonstrated that the change of reduced scattering coefficient of whole artery wall during heating reflected the reversible denaturation of the collagen in artery wall. Based on this phenomenon, the K was determined experimentally by backscattered light intensity measurement (at 633nm) of extracted porcine carotid artery during temperature elevation and descending (25°C-->80°C-->25°C). We employed the value of according to our earlier report in which the time-and temperature- dependent irreversible denaturation amount of the artery collagen fiber that was assessed by the artery birefringence. Then, the time- and temperature- dependent reversible (irreversible) denaturation fraction defined as the reversible ((irreversible) denatured collagen amount) / (total collagen amount) was calculated by the model. Thermo-mechanical analysis of artery wall was performed to compare the arterial mechanical behaviors (softening, shrinkage) during heating with the calculated denaturation fraction with the model. In any artery temperature condition in 70-80°, the irreversible denaturation fraction at which the artery thermal shrinkage started was estimated to be around 20%. On the other hand, the calculated irreversible denaturation fraction remained below

  1. Denatured ethanol release into gasoline residuals, Part 1: Source behaviour

    Science.gov (United States)

    Freitas, Juliana G.; Barker, James F.

    2013-05-01

    With the increasing use of ethanol in fuels, it is important to evaluate its fate when released into the environment. While ethanol is less toxic than other organic compounds present in fuels, one of the concerns is the impact ethanol might have on the fate of gasoline hydrocarbons in groundwater. One possible concern is the spill of denatured ethanol (E95: ethanol containing 5% denaturants, usually hydrocarbons) in sites with pre-existing gasoline contamination. In that scenario, ethanol is expected to increase the mobility of the NAPL phase by acting as a cosolvent and decreasing interfacial tension. To evaluate the E95 behaviour and its impacts on pre-existing gasoline, a field test was performed at the CFB-Borden aquifer. Initially gasoline contamination was created releasing 200 L of E10 (gasoline with 10% ethanol) into the unsaturated zone. One year later, 184 L of E95 was released on top of the gasoline contamination. The site was monitored using soil cores, multilevel wells and one glass access tube. At the end of the test, the source zone was excavated and the compounds remaining were quantified. E95 ethanol accumulated and remained within the capillary fringe and unsaturated zone for more than 200 days, despite ~ 1 m oscillations in the water table. The gasoline mobility increased and it was redistributed in the source zone. Gasoline NAPL saturations in the soil increased two fold in the source zone. However, water table oscillations caused a separation between the NAPL and ethanol: NAPL was smeared and remained in deeper positions while ethanol moved upwards following the water table rise. Similarly, the E95 denaturants that initially were within the ethanol-rich phase became separated from ethanol after the water table oscillation, remaining below the ethanol rich zone. The separation between ethanol and hydrocarbons in the source after water table oscillation indicates that ethanol's impact on hydrocarbon residuals is likely limited to early times.

  2. Test Your Sodium Smarts

    Science.gov (United States)

    ... You may be surprised to learn how much sodium is in many foods. Sodium, including sodium chloride ... foods with little or no salt. Test your sodium smarts by answering these 10 questions about which ...

  3. Strategies for denaturing the weapons-grade plutonium stockpile

    Energy Technology Data Exchange (ETDEWEB)

    Buckner, M.R.; Parks, P.B.

    1992-10-01

    In the next few years, approximately 50 metric tons of weapons-grade plutonium and 150 metric tons of highly-enriched uranium (HEU) may be removed from nuclear weapons in the US and declared excess. These materials represent a significant energy resource that could substantially contribute to our national energy requirements. HEU can be used as fuel in naval reactors, or diluted with depleted uranium for use as fuel in commercial reactors. This paper proposes to use the weapons-grade plutonium as fuel in light water reactors. The first such reactor would demonstrate the dual objectives of producing electrical power and denaturing the plutonium to prevent use in nuclear weapons.

  4. RNA Denaturation: Excluded Volume, Pseudoknots, and Transition Scenarios

    Science.gov (United States)

    Baiesi, M.; Orlandini, E.; Stella, A. L.

    2003-11-01

    A lattice model of RNA denaturation which fully accounts for the excluded volume effects among nucleotides is proposed. A numerical study shows that interactions forming pseudoknots must be included in order to get a sharp continuous transition. Otherwise a smooth crossover occurs from the swollen linear polymer behavior to highly ramified, almost compact conformations with secondary structures. In the latter scenario, which is appropriate when these structures are much more stable than pseudoknot links, probability distributions for the lengths of both loops and main branches obey scaling with nonclassical exponents.

  5. DSC study of cold and heat denaturation processes of β-lactoglobulin A with guanidine hydrochloride

    Institute of Scientific and Technical Information of China (English)

    王邦宁; 谈夫

    1997-01-01

    The cold and heat denaturations of bovine β-lactoglobuhn A (β-lg A) has been studied in solutions of guanidine hydrochloride (GuHCl) by differential scanning calorimelry (DSC) The experimental results are presented and discussed.It is shown that the number of protons bound by the monomeric molecules of β-lg A was unchanged before and after its heat denaturation below pH 3,and that the activation energy of the heat denaturation was depressed owing to the presence of GuHCl.In the solutions with 2.50 and 3.06 mol/L of GuHCl,both the cold and heat denat-urations of β-lg A were observed.In comparison with the heat denaturation,the activation energy of cold denaturation was far lower and the number of GuHCl molecules bound by the unfolded polypeptide chains after cold denaturation increased a lot.The absolute value of the enthalpy of cold denaturation was larger than that of heat denaturation It was found by the analysis that the contribution to the total denaturational enthalpy of conformational change i

  6. Low sodium diet (image)

    Science.gov (United States)

    ... for you. Look for these words on labels: low-sodium, sodium-free, no salt added, sodium-reduced, or ... for you. Look for these words on labels: low-sodium, sodium-free, no salt added, sodium-reduced, or ...

  7. Calorimetric Study of Thermal Denaturation of Superoxide Dismutase

    Institute of Scientific and Technical Information of China (English)

    王邦宁; 谈夫

    1994-01-01

    The thermal denaturation of superoxide dismutase (SOD) from bovine erythrocytes was studied at various pH values of different buffers and at various concentrations of solutions of two neutral salts by differential scanning calorimetry. The experiments performed indicate that the PIPES is a buffer non-coordinating with the SOD, and that the binding of the anions studied influences more or less the thermal denaturation of SOD, but the effect on the oxidation form of SOD is more apparent. A new conformer of SOD with lower thermostability was discovered by the experiments performed in different buffers at certain pH values higher than the isoelectric point of SOD, or at higher concentrations of neutral salt solutions. The new conformer may be converted irreversibly into the usual conformer with high thermostability during heating. Based on the thermodynamic parameters obtained in distilled water and by thermodynamic analysis using the Ooi’s model, it is revealed that the large enthalpy △Hdc contributed by

  8. [Characterization of thermal denaturation process of proteinase K by spectrometry].

    Science.gov (United States)

    Zhang, Qi-Bing; Na, Xin-Zhu; Yin, Zong-Ning

    2013-07-01

    The effect of different temperatures on the activity and conformational changes of proteinase K was studied. Methods Proteinase K was treated with different temperatures, then denatured natural substrate casein was used to assay enzyme activity, steady-state and time-resolved fluorescence spectroscopy was used to study tertiary structure, and circular dichroism was used to study secondary structure. Results show with the temperature rising from 25 to 65 degrees C, the enzyme activity and half-life of proteinase K dropped, maximum emission wavelength red shifted from 335 to 354 nm with fluorescence intensity decreasing. Synchronous fluorescence intensity of tryptophan residues decreased and that of tyrosine residues increased. Fluorescence lifetime of tryptophan residues reduced from 4. 427 1 to 4. 032 4 ns and the fraction of alpha-helix dropped. It was concluded that it is simple and accurate to use steady-state/time-resolved fluorescence spectroscopy and circular dichroism to investigate thermal stability of proteinase K. Thermal denaturation of proteinase K followed a three-state process. Fluorescence intensity of proteinase K was affected by fluorescence resonance energy transfer from tyrosine to tryptophan residues. The alpha-helix was the main structure to maintain conformational stability of enzyme active site of proteinase K.

  9. Denatured Thermodynamics of Proteins in Weak Cation-exchange Chromatography

    Institute of Scientific and Technical Information of China (English)

    LI Rong; CHEN Guo-Liang

    2003-01-01

    The thermostability of some proteins in weak cation-exchange chromatography was investigated at 20-80 ℃. The results show that there is a fixed thermal denaturation transition temperature for each protein. The appearance of the thermal transition temperature indicates that the conformations of the proteins are destroyed seriously. The thermal behavior of the proteins in weak cation-exchange and hydrophobic interaction chromatographies were compared in a wide temperature range. It was found that the proteins have a higher thermostability in a weak cation-exchange chromatography system. The thermodynamic parameters(ΔH0, ΔS0) of those proteins were determined by means of Vant Hoff relationship(lnk-1/T). According to standard entropy change(ΔS0), the conformational change of the proteins was judged in the chromatographic process. The linear relationships between ΔH0 and ΔS0 can be used to evaluate "compensation temperature"(β) at the protein denaturation and identify the identity of the protein retention mechanism in weak cation-exchange chromatography.

  10. Optical real-time measurement of collagen denaturation

    Science.gov (United States)

    Sankaran, Vanitha; Walsh, Joseph T., Jr.

    1997-06-01

    Linear birefringence is a property of collagenous tissue that results from both its composition and structure. Previous investigations have shown that birefringence provides an indication of structural changes in collagen during slow heating. We now report the birefringent response of both mature and young rat tail tendon to laser-heating. The results indicate that denaturation of collagen from mature rats induced by a 200-microsecond(s) -long Ho:YAG laser pulse may not be described accurately by kinetic parameters. Several second-long pulses of CO2 laser pulse may not be described from young rats fit an Arrhenius model with Ea equals 12.1 kcal/mol and A equals e18.03 s-1. Typically, for slow-heating of collagen, Ea equals kcal/mol and A equals e120 s-1. Thus, it seems likely that the temperature and energy needed to initiate collagen denaturation is lower in young collagen, possibly due to its decreased hydroxyproline content and consequent decreased thermal stability.

  11. Second-harmonic generation investigation of collagen thermal denaturation

    Science.gov (United States)

    Chen, Wei-Liang; Sun, Yen; Lin, Sung-Jan; Jee, Shiou-Hwa; Chen, Yang-Fang; Lin, Ling-Chih; So, Peter T. C.; Dong, Chen-Yuan

    2007-02-01

    Using the technique of second-harmonic generation (SHG) microscopy we obtained large area image of type I collagen from rat tail tendon as it is heated from 40°C to 70°C for 0 to 180 minutes. The high resolution images allowed us to investigate the collagen structural change. We observed that heating the tendon below the temperature of 54°C does not produce any change in the averaged SHG intensity. At the heating temperature of 54°C and above, we find that increasing the heating temperature and time leads to decreasing SHG intensity. As the tendon is heated above 54°C, a decrease in the SHG signal occurs uniformly throughout the tendon, but the regions where the SHG signal vanishes form a tiger-tail like pattern. By comparing the relative SHG intensities in small and large areas, we found that the denaturation process responsible for forming the tiger-tail like pattern occurs at a higher rate than the global denaturation process occurring throughout the tendon. Our results show that second-harmonic generation microscopy is effective in monitoring the thermal damage to collagen and has potential applications in biomedicine.

  12. Heterogeneity of mitochondrial DNA from Saccharomyces carlsbergensis. Denaturation mapping by electron microscopy.

    DEFF Research Database (Denmark)

    Christiansen, Gunna; Christiansen, C; Bak, AL

    1975-01-01

    Electronmicroscopic observation of the denaturation pattern of 130 partially denaturated linear mitochondrial DNA molecules from Saccharomyces carlsbergensis was used to investigate the distribution of AT-rich sequences within the mitochondrial genome. The molecules were observed after heating...... denaturated sequences in the mitochondrial DNA. These sequences which presumably correspond to the very AT-rich regions, known to exist in the yeast mitochondrial DNA, were found at intervals of about 0.5 - 3 mum on the map....

  13. 27 CFR 21.92 - Denaturants listed as U.S.P. or N.F.

    Science.gov (United States)

    2010-04-01

    ....P. or N.F. 21.92 Section 21.92 Alcohol, Tobacco Products and Firearms ALCOHOL AND TOBACCO TAX AND... for Denaturants § 21.92 Denaturants listed as U.S.P. or N.F. Denaturing materials and products listed in this part as “U.S.P.” or “N.F.” shall meet the specifications set forth in the current...

  14. Electrochemical behaviour of denatured ethanol for use in direct ethanol fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Bayer, Domnik; Kintzel, Birgit; Joos, Martin; Cremers, Carsten; Tuebke, Jens [Fraunhofer-Institut fuer Chemische Technologie (ICT), Pfinztal (Germany)

    2010-07-01

    In the present study, two denaturing agents, an adjuvant to a denaturing agent and a mixture of a denaturing agend and the adjuvant were tested with regard to their fuel cell compatibility. Therefore, various electrochemical tests including cyclic voltammetry, chronoamperometry and differential electrochemical mass spectroscopy have been conducted at platinum as model catalyst in acidic and alkaline medium. In addition, the most promising denaturing agent, a mixture of tert-butyl ethyl ether (ETBE) with the adjuvant Bitrex {sup registered}, has also been tested at commercial fuel cell catalysts in both acidic and alkaline media. (orig.)

  15. Visualization of early events in acetic acid denaturation of HIV-1 protease: a molecular dynamics study.

    Directory of Open Access Journals (Sweden)

    Aditi Narendra Borkar

    Full Text Available Protein denaturation plays a crucial role in cellular processes. In this study, denaturation of HIV-1 Protease (PR was investigated by all-atom MD simulations in explicit solvent. The PR dimer and monomer were simulated separately in 9 M acetic acid (9 M AcOH solution and water to study the denaturation process of PR in acetic acid environment. Direct visualization of the denaturation dynamics that is readily available from such simulations has been presented. Our simulations in 9 M AcOH reveal that the PR denaturation begins by separation of dimer into intact monomers and it is only after this separation that the monomer units start denaturing. The denaturation of the monomers is flagged off by the loss of crucial interactions between the α-helix at C-terminal and surrounding β-strands. This causes the structure to transit from the equilibrium dynamics to random non-equilibrating dynamics. Residence time calculations indicate that denaturation occurs via direct interaction of the acetic acid molecules with certain regions of the protein in 9 M AcOH. All these observations have helped to decipher a picture of the early events in acetic acid denaturation of PR and have illustrated that the α-helix and the β-sheet at the C-terminus of a native and functional PR dimer should maintain both the stability and the function of the enzyme and thus present newer targets for blocking PR function.

  16. Synthesis of dodecyl lauroyl benzene sulfonate and its application in enhanced oil recovery

    Energy Technology Data Exchange (ETDEWEB)

    Cui, Zhenggang; Wu, Le; Sun, Mingming; Jiang, Jian-zhong; Wang, Feng [Jiangnan Univ., Wuxi (China). School of Chemical and Material Engineering

    2011-09-15

    A new hydrophobic surfactant, dodecyl lauroyl benzene sulfonate (DLBS), was synthesized and its application in enhanced oil recovery by alkali-surfactant-polymer (ASP) flooding was studied. The results show that DLBS can be synthesized by reaction of industrial dodecyl benzene with lauroyl chloride in the presence of AlCl{sub 3}, followed by sulfonation with ClSO{sub 3}H and neutralization with NaOH. The lauroyl-group is confirmed to be connected to the para-position of the alkylbenzene by1HNMR spectrum. The synthesized DLBS is well soluble in pure water and reservoir (connate) water at 45 C. It is highly surface active which is indicated by its low CMC of 1.1 . 10{sup -5} mol/L, and its low surface tension, {gamma}{sub cmc} of 28.6 mN m{sup -1}. By mixing with heavy alkylbenzene sulfonates of relatively low average molar mass (387g mol{sup -1}) at a total surfactant concentration of 5 mM, DLBS can reduce the interfacial tension of Daqing crude oil/connate water to an order of 10{sup -3} mN/m at 45 C in the presence of 0.5-1.0 wt.% NaOH and 1000 mg L{sup -1} of polymer. If the NaOH was replaced by a gentle alkaline salt, Na{sub 2}CO{sub 3}, certain amounts of dodecyl dimethyl carboxy betaine were added and the concentration of Na{sub 2}CO{sub 3} was increased to 1.2-2.0 wt.%, the interfacial tension of Daqing crude oil/connate water can also be reduced to an ultralow value. Therefore DLBS is a good hydrophobic surfactant applicable in ASP flooding with either NaOH or Na{sub 2}CO{sub 3} as alkaline agents. (orig.)

  17. DCl Transport through Dodecyl Sulfate Films on Salty Glycerol: Effects of Seawater Ions on Gas Entry.

    Science.gov (United States)

    Shaloski, Michael A; Sobyra, Thomas B; Nathanson, Gilbert M

    2015-12-17

    Gas-liquid scattering experiments were employed to measure the entry and dissociation of the acidic gas DCl into salty glycerol coated with dodecyl sulfate ions (DS(-) = CH3(CH2)11OSO3(-)). Five sets of salty solutions were examined: 0.25 and 0.5 M NaCl, 0.25 M MgCl2, 0.25 M CaCl2, and artificial sea salt. DS(-) bulk concentrations were varied from 0 to 11 mM, generating DS(-) surface coverages of up to 34% of a compact monolayer, as determined by surface tension and argon scattering measurements. DS(-) surface segregation is enhanced by the dissolved salts in the order MgCl2 ≈ CaCl2 > sea salt > NaCl. We find that DCl penetration through the dodecyl chains decreases at first gradually and then sharply as more chains segregate to the surface, dropping from 70% entry on bare glycerol to 11% for DS(-) surface concentrations of 1.8 × 10(14) cm(-2). When plotted against DS(-) surface concentration, the DCl entry probabilities fall within a single band for all solutions. These observations imply that the monovalent Na(+) and divalent Ca(2+) and Mg(2+) ions do not bind differently enough to the ROSO3(-) headgroup to significantly alter the diffusive passage of DCl molecules through the dodecyl chains at the same DS(-) chain density. The chief difference among the salts is the greater propensity for the divalent salts to expel the soluble ionic surfactant to the surface.

  18. Aggregation of Dodecyl 1-Pyrenylmethyl Ether and Its Application in Structure-Polarity Relations of Aggregates

    Institute of Scientific and Technical Information of China (English)

    SANG,Da-Yong; TIAN,Juan; JI,Guo-Zhen

    2006-01-01

    The aggregation behavior of dodecyl 1-pyrenylmethyl ether was studied in dioxane-water mixture solvents by fluorescence techniques. The labeled pyrenyl group was effective in monitoring the polarity change of its environment during aggregation processes. Based on the structural effects such as chain-length effect, self-coiling effect,and branch-group effect on the polarity of the probe environment, the structure features of aggregates were discussed and have been used to interpret the effect of the structural features on the aggregates formed by three cholesteryl esters and three long chain alkanes.

  19. Consistent View of Polypeptide Chain Expansion in Chemical Denaturants from Multiple Experimental Methods.

    Science.gov (United States)

    Borgia, Alessandro; Zheng, Wenwei; Buholzer, Karin; Borgia, Madeleine B; Schüler, Anja; Hofmann, Hagen; Soranno, Andrea; Nettels, Daniel; Gast, Klaus; Grishaev, Alexander; Best, Robert B; Schuler, Benjamin

    2016-09-14

    There has been a long-standing controversy regarding the effect of chemical denaturants on the dimensions of unfolded and intrinsically disordered proteins: A wide range of experimental techniques suggest that polypeptide chains expand with increasing denaturant concentration, but several studies using small-angle X-ray scattering (SAXS) have reported no such increase of the radius of gyration (Rg). This inconsistency challenges our current understanding of the mechanism of chemical denaturants, which are widely employed to investigate protein folding and stability. Here, we use a combination of single-molecule Förster resonance energy transfer (FRET), SAXS, dynamic light scattering (DLS), and two-focus fluorescence correlation spectroscopy (2f-FCS) to characterize the denaturant dependence of the unfolded state of the spectrin domain R17 and the intrinsically disordered protein ACTR in two different denaturants. Standard analysis of the primary data clearly indicates an expansion of the unfolded state with increasing denaturant concentration irrespective of the protein, denaturant, or experimental method used. This is the first case in which SAXS and FRET have yielded even qualitatively consistent results regarding expansion in denaturant when applied to the same proteins. To more directly illustrate this self-consistency, we used both SAXS and FRET data in a Bayesian procedure to refine structural ensembles representative of the observed unfolded state. This analysis demonstrates that both of these experimental probes are compatible with a common ensemble of protein configurations for each denaturant concentration. Furthermore, the resulting ensembles reproduce the trend of increasing hydrodynamic radius with denaturant concentration obtained by 2f-FCS and DLS. We were thus able to reconcile the results from all four experimental techniques quantitatively, to obtain a comprehensive structural picture of denaturant-induced unfolded state expansion, and to

  20. Irreversible denaturation of maltodextrin glucosidase studied by differential scanning calorimetry, circular dichroism, and turbidity measurements.

    Science.gov (United States)

    Goyal, Megha; Chaudhuri, Tapan K; Kuwajima, Kunihiro

    2014-01-01

    Thermal denaturation of Escherichia coli maltodextrin glucosidase was studied by differential scanning calorimetry, circular dichroism (230 nm), and UV-absorption measurements (340 nm), which were respectively used to monitor heat absorption, conformational unfolding, and the production of solution turbidity. The denaturation was irreversible, and the thermal transition recorded at scan rates of 0.5-1.5 K/min was significantly scan-rate dependent, indicating that the thermal denaturation was kinetically controlled. The absence of a protein-concentration effect on the thermal transition indicated that the denaturation was rate-limited by a mono-molecular process. From the analysis of the calorimetric thermograms, a one-step irreversible model well represented the thermal denaturation of the protein. The calorimetrically observed thermal transitions showed excellent coincidence with the turbidity transitions monitored by UV-absorption as well as with the unfolding transitions monitored by circular dichroism. The thermal denaturation of the protein was thus rate-limited by conformational unfolding, which was followed by a rapid irreversible formation of aggregates that produced the solution turbidity. It is thus important to note that the absence of the protein-concentration effect on the irreversible thermal denaturation does not necessarily means the absence of protein aggregation itself. The turbidity measurements together with differential scanning calorimetry in the irreversible thermal denaturation of the protein provided a very effective approach for understanding the mechanisms of the irreversible denaturation. The Arrhenius-equation parameters obtained from analysis of the thermal denaturation were compared with those of other proteins that have been reported to show the one-step irreversible thermal denaturation. Maltodextrin glucosidase had sufficiently high kinetic stability with a half-life of 68 days at a physiological temperature (37°C).

  1. Residual ordered structure in denatured proteins and the problem of protein folding.

    Science.gov (United States)

    Basharov, Mahmud A

    2012-02-01

    Structural characteristics of numerous globular proteins in the denatured state have been reviewed using literature data. Recent more precise experiments show that in contrast to the conventional standpoint, proteins under strongly denaturing conditions do not unfold completely and adopt a random coil state, but contain significant residual ordered structure. These results cast doubt on the basis of the conventional approach representing the process of protein folding as a spontaneous transition of a polypeptide chain from the random coil state to the unique globular structure. The denaturation of proteins is explained in terms of the physical properties of proteins such as stability, conformational change, elasticity, irreversible denaturation, etc. The spontaneous renaturation of some denatured proteins most probably is merely the manifestation of the physical properties (e.g., the elasticity) of the proteins per se, caused by the residual structure present in the denatured state. The pieces of the ordered structure might be the centers of the initiation of renaturation, where the restoration of the initial native conformation of denatured proteins begins. Studies on the denaturation of proteins hardly clarify how the proteins fold into the native conformation during the successive residue-by-residue elongation of the polypeptide chain on the ribosome.

  2. The generation of denatured reactor plutonium by different options of the fuel cycle

    Energy Technology Data Exchange (ETDEWEB)

    Broeders, C.H.M.; Kessler, G. [Inst. for Neutron Physics and Reactor Technology, Research Center Karlsruhe (Germany)

    2006-11-15

    Denatured (proliferation resistant) reactor plutonium can be generated in a number of different fuel cycle options. First denatured reactor plutonium can be obtained if, instead of low enriched U-235 PWR fuel, re-enriched U-235/U-236 from reprocessed uranium is used (fuel type A). Also the envisaged existing 2,500 t of reactor plutonium (being generated world wide up to the year 2010), mostly stored in intermediate fuel storage facilities at present, could be converted during a transition phase into denatured reactor plutonium by the options fuel type B and D. Denatured reactor plutonium could have the same safeguards standard as present low enriched (<20% U-235) LWR fuel. It could be incinerated by recycling once or twice in PWRs and subsequently by multi-recycling in FRs (CAPRA type or IFRs). Once denatured, such reactor plutonium could remain denatured during multiple recycling. In a PWR, e.g., denatured reactor plutonium could be destroyed at a rate of about 250 kg/GWey. While denatured reactor plutonium could be recycled and incinerated under relieved IAEA safeguards, neptunium would still have to be monitored by the IAEA in future for all cases in which considerable amounts of neptunium are produced. (orig.)

  3. New fluorescent polymeric nanocomposites synthesized by antimony dodecyl-mercaptide thermolysis in polymer

    Directory of Open Access Journals (Sweden)

    2009-04-01

    Full Text Available In this work, the formation of semiconductive Sb2S3 nanoparticles inside amorphous polystyrene has been achieved by thermal degradation of the corresponding antimony dodecyl-mercaptide, Sb(SC12H253. The thermolysis of the dodecyl-mercaptide precursor was studied as both pure phase and mercaptide solution in polystyrene. The thermal decomposition of the antimony mercaptide precursor at 350°C, under vacuum, showed the formation of a mixture of antimony trisulfide (stibnite, Sb2S3 and zero-valent antimony (Sb phase. X-ray Powder Diffraction (XRD and Rietveld analysis carried out on the obtained nanostructured powder confirmed the presence of Sb and Sb2S3 phases in 10.4 wt% and 89.6 wt% amount, respectively. The same pyrolysis reaction was carried out in the polymer and the resulting nanocomposite material was characterized by X-ray diffraction (XRD, transmission electron microscopy (TEM, UV-VIS spectroscopy, and fluorescence spectroscopy. The nanocomposite structural characterization indicated the presence of well-dispersed nanoclusters of antimony and stibnite (15–30 nm in size inside the amorphous polymeric phase. Optical measurements on the obtained nanocomposite films showed a strong emission at 432 nm upon excitation at 371 nm, probably related to the presence of Sb2S3 nanoclusters.

  4. In Vitro Reassembly of Tobacco Ribulose-1,5-bisphosphate Carboxylase/ Oxygenase from Fully Denatured Subunits

    Institute of Scientific and Technical Information of China (English)

    Zhen-Hua YONG; Gen-Yun CHEN; Jiao-Nai SHI; Da-Quan XU

    2006-01-01

    It has been generally proved impossible to reassemble ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) from fully denatured subunits in vitro in higher plant, because large subunit of fully denatured Rubisco is liable to precipitate when the denaturant is removed by common methods of direct dilution and one-step dialysis. In our experiment, the problem of precipitation was resolved by an improved gradual dialysis method, which gradually decreased the concentration of denaturant. However, fully denatured Rubisco subunits still could not be reassembled into holoenzyme using gradual dialysis unless chaperonin 60was added. The restored activity of reassembled Rubisco was approximately 8% of natural enzyme. The quantity of reassembled Rubisco increased greatly when heat shock protein 70 was present in the reassembly process. ATP and Mg2+ were unnecessary for in vitro reassembly of Rubisco, and Mg2+ inhibited the reassembly process. The reassembly was weakened when ATP, Mg2+ and K+ existed together in the reassembly process.

  5. Dynamic light scattering study of peanut agglutinin: Size, shape and urea denaturation

    Indian Academy of Sciences (India)

    Sagarika Dev; Avadhesha Surolia

    2006-12-01

    Peanut agglutinin (PNA) is a homotetrameric protein with a unique open quaternary structure. PNA shows non-two state profile in chaotrope induced denaturation. It passes through a monomeric molten globule like state before complete denaturation (Reddy et al 1999). This denaturation profile is associated with the change in hydrodynamic radius of the native protein. Though the molten globule-like state is monomeric in nature it expands in size due to partial denaturation. The size and shape of the native PNA as well as the change in hydrodynamic radius of the protein during denaturation has been studied by dynamic light scattering (DLS). The generation of two species is evident from the profile of hydrodynamic radii. This study also reveals the extent of compactness of the intermediate state.

  6. In situ observation of collagen thermal denaturation by second harmonic generation microscopy

    Science.gov (United States)

    Liao, C.-S.; Zhuo, Z.-Y.; Yu, J.-Y.; Chao, P.-H. G.; Chu, S.-W.

    2010-02-01

    Collagen denaturation is of fundamental importance for clinical treatment. Conventionally, the denaturation process is quantified by the shrinkage of collagen fibers, but the underlying molecular origin has not been fully understood. Since second harmonic generation (SHG) is related to the molecular packing of the triple helix in collagen fibers, this nonlinear signal provides an insight of molecular dynamics during thermal denaturation. With the aid of SHG microscopy, we found a new step in collagen thermal denaturation process, de-crimp. During the de-crimp step, the characteristic crimp pattern of collagen fascicles disappeared due to the breakage of interconnecting bonds between collagen fibrils, while SHG intensity remained unchanged, suggesting the intactness of the triple helical molecules. At higher temperature, shrinkage is observed with strongly reduced SHG intensity, indicating denaturation at the molecular level.

  7. Refolding of detergent-denatured lysozyme using β-cyclodextrin-assisted ion exchange chromatography.

    Science.gov (United States)

    Zhang, Li; Zhang, Qinming; Wang, Chaozhan

    2013-03-01

    Chromatography-based protein refolding is widely used. Detergent is increasingly used for protein solubilization from inclusion bodies. Therefore, it is necessary to develop a refolding method for detergent-denatured/solubilized proteins based on liquid chromatography. In the present work, sarkosyl-denatured/dithiothreitol-reduced lysozyme was used as a model, and a refolding method based on ion exchange chromatography, assisted by β-cyclodextrin, was developed for refolding detergent-denatured proteins. Many factors affecting the refolding, such as concentration of urea, concentration of β-cyclodextrin, pH and flow rate of mobile phases, were investigated to optimize the refolding conditions for sarkosyl-denatured lysozymes. The results showed that the sarkosyl-denatured lysozyme could be successfully refolded using β-cyclodextrin-assisted ion exchange chromatography.

  8. Tungsten-induced denaturation and aggregation of epoetin alfa during primary packaging as a cause of immunogenicity.

    Science.gov (United States)

    Seidl, Andreas; Hainzl, Otmar; Richter, Marleen; Fischer, Robert; Böhm, Stephan; Deutel, Britta; Hartinger, Martin; Windisch, Jörg; Casadevall, Nicole; London, Gerard Michel; Macdougall, Iain

    2012-06-01

    Following two cases of neutralizing antibodies to epoetin alfa in an investigational clinical study, a small number of individual syringes of two drug product batches were found to contain unusually high levels of aggregation at the end of the clinical trial. We undertook an extensive analytical approach to determine the root-cause of the increased aggregation in the affected batches. Soluble tungsten was found in the syringes, most likely derived from the pins used to manufacture the syringes. Spiking of epoetin alfa with sodium polytungstate or an extract of tungsten pins used to manufacture the syringes induced the formation of aggregates, both dimers that appeared to be covalently linked by disulphide bonds as well as higher-order aggregates. Sodium polytungstate had also a strong denaturing effect on the protein. We propose tungsten-mediated unfolding and aggregation of epoetin alfa in pre-filled syringes as a potential root cause for increased immunogenicity. This finding may be more broadly applicable to this and other classes of therapeutic proteins.

  9. Dissociative mechanism of F-actin thermal denaturation.

    Science.gov (United States)

    Mikhailova, V V; Kurganov, B I; Pivovarova, A V; Levitsky, D I

    2006-11-01

    We have applied differential scanning calorimetry to investigate thermal unfolding of F-actin. It has been shown that the thermal stability of F-actin strongly depends on ADP concentration. The transition temperature, T(m), increases with increasing ADP concentration up to 1 mM. The T(m) value also depends on the concentration of F-actin: it increases by almost 3 degrees C as the F-actin concentration is increased from 0.5 to 2.0 mg/ml. Similar dependence of the T(m) value on protein concentration was demonstrated for F-actin stabilized by phalloidin, whereas it was much less pronounced in the presence of AlF4(-). However, T(m) was independent of protein concentration in the case of monomeric G-actin. The results suggest that at least two reversible stages precede irreversible thermal denaturation of F-actin; one of them is dissociation of ADP from actin subunits, and another is dissociation of subunits from the ends of actin filaments. The model explains why unfolding of F-actin depends on both ADP and protein concentration.

  10. Nonisothermal denaturation kinetics of human hair and the effects of oxidation.

    Science.gov (United States)

    Wortmann, F-J; Popescu, C; Sendelbach, G

    2006-12-15

    Human hair as alpha-keratin fiber exhibits a complex morphology, which for the context of this investigation is considered as a filament/matrix-composite, comprising the intermediate filaments (IF) and a variety of amorphous protein components as matrix. Differential scanning calorimetry (DSC) under aqueous conditions was used to analyze the denaturation of the alpha-helical material in the IFs and to assess the changes imparted by repeated, oxidative bleaching processes. The DSC curves were submitted to kinetic analysis by applying the Friedman method and assuming first order kinetics. It was found that the course of the denaturation process remains largely unchanged through oxidation, despite the fact that pronounced decreases of denaturation temperature as well as of enthalpy occur. In parallel, the reaction rate constant at the denaturation temperature, k(TD), increases with repeated treatments, that is with cumulative chemical modification. However, this effect is in fact small compared to the overall change of k(T) through the denaturation process. This leads to conclude that once the temperature rise in combination with the chemical change has induced a suitable drop of the viscosity of the matrix around the IFs, denaturation of the remaining helical material occurs along a pathway that is largely independent of temperature and of the pretreatment history. This emphasizes the kinetic control of the matrix over the denaturation process of the helical segments in the filament/matrix composite. Copyright 2006 Wiley Periodicals, Inc.

  11. Studies on the refolding of the reduced-denatured insulin with size exclusion chromatography

    Institute of Scientific and Technical Information of China (English)

    BAI Quan; KONG Yu; DONG Cuihua; GENG Xindu

    2005-01-01

    The refolding of the reduced-denatured insulin from bovine pancreas was investigated with the size exclusion chromatography (SEC). It was shown that the reduced-denatured insulin originally denatured with 7.0 mol·L-1 guanidine hydrochloride (GuHCl) or 8.0 mol·L-1 urea could not be refolded with a non-oxidized mobile phase. Although the oxidized and reduced glutathione (GSSG and GSH) were employed in the oxidized mobile phase, the reduced-denatured insulin still could not be renatured. However, in the presence of 2.0 mol·L-1 urea in the oxidized mobile phase employed, the reduced-denatured insulin can be refolded with SEC, and the aggregation of denatured insulin can be diminished by urea. In addition, the disulfide exchange of reduced-denatured insulin also can be accelerated with GSSG/GSH in the oxidized mobile phase. The three disulfide bridges of insulin were formed correctly and the reduced-unfolded insulin can be renatured completely. The results were further tested with reversed-phase liquid chromatography (RPLC) and hydrophobic interaction chromatography (HIC).

  12. STUDY OF SODIUM, POTASSIUM, AND CALCIUM SALTS INFLUENCE ON PROTEIN STABILITY BY DIFFERENTIAL SCANNING CALORIMETRY

    Directory of Open Access Journals (Sweden)

    E. K. Tunieva

    2016-01-01

    Full Text Available Abstract Study of protein stability depending on the various technological factors allows to directionally adjust the physicochemical properties of raw meat and the quality of finished meat products. The paper investigates the possibility of using the DSC to study the influence of monovalent and divalent salts on protein thermal stability. In order to determine the effect of sodium chloride and its substitutes, potassium and calcium salts, on the thermal stability of proteins, the studies were carried out with grinded pork longissimus muscle samples salted with sodium chloride at level of 2.0% and with salt compositions containing reduced by 50% level of sodium chloride (a mixture of sodium and potassium chlorides; a mixture of sodium, potassium, and calcium chlorides using the differential scanning calorimeter DSC Q 2000 in the temperature range of 5 °C to 100 °C and the temperature change rate of 1 K/min. It was found that the addition of potassium chloride instead of 50% of sodium chloride had no significant effect on actin and myosin resistance to thermal denaturation. Meat salting using the mixture of sodium, potassium, and calcium chlorides resulted in decrease of myofibrillar proteins stability indicating the destabilizing effect of calcium on actin and myosin. A negative correlation between the magnitude of the ionic strength and the temperature of myosin and actin denaturation has been found. The correlation coefficients were minus 0.99 and minus 0.95 for myosin and actin respectively. Reduction of denaturation temperature for myofibrillar proteins in the presence of calcium chloride opens perspectives to study the possibility of heat treatment at lower temperatures for meat products with reduced sodium content.

  13. MICELLIZATION STUDIES OF DODECYL BENZENESULFONIC ACID AND ITS INTERACTION WITH POLYVINYLPYRROLIDONE

    Institute of Scientific and Technical Information of China (English)

    Mohammad Saleem Khan; Zarshad Ali

    2005-01-01

    Dodecyl benzenesulfonic acid (DBSA) surfactant was used in the present study to find the effect of concentration on its electrical conductance in solution from 293-323 K above and below the critical micelle concentration (CMC). The micellization parameters i.e. degree of counter ion binding (β), aggregation number (n) and number of counter ion micelle(m) were measured. The interaction of DBSA with polyvinylpyrrolidone (PVP) was also studied at 293 K through conductance and surface tension measure ments. A number of important parameters i.e. critical aggregation concentration(CAC), Gibb's free energy (AG) and binding ratio (R) were determined and the effect of NaCl on the CAC and polymer saturation point (PSP) was also investigated.

  14. Esterification process to synthesize isopropyl chloroacetate catalyzed by lanthanum dodecyl sulfate

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Jiasheng; Zhang, Jie; Yin, Xiangyu; Zhang, He; Qian, Jianhua; Liu, Lianli, E-mail: jiashengxu@bhu.edu.c [Bohai University, Jinzhou (China). Liaoning Province Research Center for Silicon Materials Engineering Technology. Liaoning Province Key Laboratory for Synthesis and Application of Functional Compounds; Yang, Dongjiang [Griffith University (Australia). Environmental Futures Centre and Griffith School of Environment; Liu, Xiaoyang [Jilin University (China). College of Chemistry. State Key Lab. of Inorganic Synthesis and Preparative Chemistry

    2011-04-15

    Isopropyl chloroacetate has been synthesized by esterification of chloroacetic acid and isopropanol, using lanthanum dodecyl sulfate (LDDS) as the catalyst. Various factors that affected the esterification have been investigated, such as reaction time, different water-carrying agent and the amount of catalyst. Under the condition of 1.2/1 molar ratio of isopropanol to chloroacetic acid, 1.0% catalyst (molar percent of chloroacetic acid), 2.5 h reaction time, 5 mL cyclohexane as water-carrying agent and reflux temperature, the esterification conversion of isopropyl chloroacetate reaches 98.3%. The catalytic activity of LDDS is almost equal to that of a Bronsted acid. LDDS, as one kind of water-tolerant Lewis acid, is an excellent catalyst compared to the traditional Lewis acid. (author)

  15. Assessment of collagen crosslinking and denaturation for the design of regenerative scaffolds.

    Science.gov (United States)

    Madaghiele, Marta; Calò, Emanuela; Salvatore, Luca; Bonfrate, Valentina; Pedone, Deborah; Frigione, Mariaenrica; Sannino, Alessandro

    2016-01-01

    Crosslinking and denaturation were two variables that deeply affected the performance of collagen-based scaffolds designed for tissue regeneration. If crosslinking enhances the mechanical properties and the enzymatic resistance of collagen, while masking or reducing the available cell binding sites, denaturation has very opposite effects, as it impairs the mechanical and the enzymatic stability of collagen, but increases the number of exposed cell adhesive domains. The quantification of both crosslinking and denaturation was thus fundamental to the design of collagen-based scaffolds for selected applications. The aim of this work was to investigate the extents of crosslinking and denaturation of collagen-based films upon dehydrothermal (DHT) treatment, that is, one of the most commonly employed methods for zero-length crosslinking that shows the unique ability to induce partial denaturation. Swelling measurements, differential scanning calorimetry, Fourier transform infrared spectroscopy, colorimetric assays for the quantification of primary amines, and mechanical tests were performed to analyze the effect of the DHT temperature on crosslinking and denaturation. In particular, chemically effective and elastically effective crosslink densities were evaluated. Both crosslinking and denaturation were found to increase with the DHT temperature, although according to different trends. The results also showed that DHT treatments performed at temperatures up to 120°C maintained the extent of denaturation under 25%. Coupling a mild DHT treatment with further crosslinking may thus be very useful not only to modulate the crosslink density, but also to induce a limited amount of denaturation, which shows potential to partially compensate the loss of cell binding sites caused by crosslinking.

  16. Urea-temperature phase diagrams capture the thermodynamics of denatured state expansion that accompany protein unfolding.

    Science.gov (United States)

    Tischer, Alexander; Auton, Matthew

    2013-09-01

    We have analyzed the thermodynamic properties of the von Willebrand factor (VWF) A3 domain using urea-induced unfolding at variable temperature and thermal unfolding at variable urea concentrations to generate a phase diagram that quantitatively describes the equilibrium between native and denatured states. From this analysis, we were able to determine consistent thermodynamic parameters with various spectroscopic and calorimetric methods that define the urea-temperature parameter plane from cold denaturation to heat denaturation. Urea and thermal denaturation are experimentally reversible and independent of the thermal scan rate indicating that all transitions are at equilibrium and the van't Hoff and calorimetric enthalpies obtained from analysis of individual thermal transitions are equivalent demonstrating two-state character. Global analysis of the urea-temperature phase diagram results in a significantly higher enthalpy of unfolding than obtained from analysis of individual thermal transitions and significant cross correlations describing the urea dependence of ΔH0 and ΔCP0 that define a complex temperature dependence of the m-value. Circular dichroism (CD) spectroscopy illustrates a large increase in secondary structure content of the urea-denatured state as temperature increases and a loss of secondary structure in the thermally denatured state upon addition of urea. These structural changes in the denatured ensemble make up ∼40% of the total ellipticity change indicating a highly compact thermally denatured state. The difference between the thermodynamic parameters obtained from phase diagram analysis and those obtained from analysis of individual thermal transitions illustrates that phase diagrams capture both contributions to unfolding and denatured state expansion and by comparison are able to decipher these contributions.

  17. Local gene delivery via endovascular stents coated with dodecylated chitosan–plasmid DNA nanoparticles

    Directory of Open Access Journals (Sweden)

    Dunwan Zhu

    2010-12-01

    Full Text Available Dunwan Zhu1*, Xu Jin2*, Xigang Leng1, Hai Wang1, Junbo Bao1, Wenguang Liu3, Kangde Yao3, Cunxian Song11Tianjin Key Laboratory of Biomedical Materials, Institute of Biomedical Engineering, Chinese Academy of Medical Sciences and Peking Union Medical College, Tianjin, China; 2Department of Anesthesia and Pain Therapy, Capital Medical University Affiliated Beijing Tiantan Hospital, Beijing, China; 3Research Institute of Polymeric Materials, Tianjin University, Tianjin, China; *Both investigators contributed equally to this work and are senior authors.Abstract: Development of efficacious therapeutic strategies to prevent and inhibit the occurrences of restenosis after percutaneous transluminal coronary angioplasty is critical for the treatment of cardiovascular diseases. In this study, the feasibility and efficiency of stents coated with dodecylated chitosan–plasmid DNA nanoparticles (DCDNPs were evaluated as scaffolds for localized and prolonged delivery of reporter genes into the diseased blood vessel wall. Dodecylated chitosan–plasmid DNA complexes formed stable positive charged nanospheres with mean diameter of approximately 90–180 nm and zeta potential of +28 ± 3 mV. As prepared DCDNPs were spray-coated on stents, a thin layer of dense DCDNPs was successfully distributed onto the metal struts of the endovascular stents as demonstrated by scanning electron microscopy. The DCDNP stents were characterized for the release kinetics of plasmid DNA, and further evaluated for gene delivery and expression both in vitro and in vivo. In cell culture, DCDNP stents containing plasmid EGFP-C1 exhibited high level of GFP expression in cells grown on the stent surface and along the adjacent area. In animal studies, reporter gene activity was observed in the region of the artery in contact with the DCDNP stents, but not in adjacent arterial segments or distal organs. The DCDNP stent provides a very promising strategy for cardiovascular gene therapy

  18. Relaxation rate for an ultrafast folding protein is independent of chemical denaturant concentration.

    Science.gov (United States)

    Cellmer, Troy; Henry, Eric R; Kubelka, Jan; Hofrichter, James; Eaton, William A

    2007-11-28

    The connection between free-energy surfaces and chevron plots has been investigated in a laser temperature jump kinetic study of a small ultrafast folding protein, the 35-residue subdomain from the villin headpiece. Unlike all other proteins that have been studied so far, no measurable dependence of the unfolding/refolding relaxation rate on denaturant concentration was observed over a wide range of guanidinium chloride concentration. Analysis with a simple Ising-like theoretical model shows that this denaturant-invariant relaxation rate can be explained by a large movement of the major free energy barrier, together with a denaturant- and reaction coordinate-dependent diffusion coefficient.

  19. Heat Denaturation of Protein Structures and Chlorophyll States in PSII Membranes

    Institute of Scientific and Technical Information of China (English)

    李冬海; 阮翔; 许强; 王可玢; 公衍道; 匡廷云; 赵南明

    2002-01-01

    Heat denaturation is an important technique in the study of the structure and function of photosynthetic proteins. Heat denaturation of photosystem II (PSII) membrane was studied using circular dichroism (CD) spectroscopy, differential scanning calorimetry (DSC) and oxygen electrode. Complete loss of oxygen-evolving activity of the PSII membrane was observed at temperatures below 45℃. The decrease of excitonic interaction between chlorophyll molecules occurred more rapidly than the change of the protein secondary structure of the PSII membrane at temperatures above 45℃. The results indicate that the protein secondary structure of the membrane proteins in PSII membranes is more stable than the excitonic interaction between chlorophyll molecules during heat denaturation.

  20. Protein denaturation and functional properties of Lenient Steam Injection heat treated whey protein concentrate

    DEFF Research Database (Denmark)

    Dickow, Jonatan Ahrens; Kaufmann, Niels; Wiking, Lars

    2012-01-01

    Whey protein concentrate (WPC) was heat treated by use of the novel heat treatment method of Lenient Steam Injection (LSI) to elucidate new functional properties in relation to heat-induced gelation of heat treated WPC. Denaturation was measured by both DSC and FPLC, and the results of the two...... methods were highly correlated. Temperatures of up to 90 °C were applicable using LSI, whereas only 68 °C could be reached by plate heat exchange before coagulation/fouling. Denaturation of whey proteins increased with increasing heat treatment temperature up to a degree of 30–35% denaturation at 90 °C...

  1. The influence of applied heat treatments on whey protein denaturation

    Directory of Open Access Journals (Sweden)

    Fetahagić Safet

    2002-01-01

    . Distribution of nitrogen matter from milk 8%+3%DWP heat treated at 85ºC/10 min, 90ºC/10 min and 95ºC/10 min to sera samples were 9.64%, 8.66% and 8.67%, respectively. Whey protein denaturation increased with increasing of the temperature of the applied heat treatment. Denaturation was the most significant for milk sample 11%.

  2. Protein folding by distributed computing and the denatured state ensemble.

    Science.gov (United States)

    Marianayagam, Neelan J; Fawzi, Nicolas L; Head-Gordon, Teresa

    2005-11-15

    The distributed computing (DC) paradigm in conjunction with the folding@home (FH) client server has been used to study the folding kinetics of small peptides and proteins, giving excellent agreement with experimentally measured folding rates, although pathways sampled in these simulations are not always consistent with the folding mechanism. In this study, we use a coarse-grain model of protein L, whose two-state kinetics have been characterized in detail by using long-time equilibrium simulations, to rigorously test a FH protocol using approximately 10,000 short-time, uncoupled folding simulations starting from an extended state of the protein. We show that the FH results give non-Poisson distributions and early folding events that are unphysical, whereas longer folding events experience a correct barrier to folding but are not representative of the equilibrium folding ensemble. Using short-time, uncoupled folding simulations started from an equilibrated denatured state ensemble (DSE), we also do not get agreement with the equilibrium two-state kinetics because of overrepresented folding events arising from higher energy subpopulations in the DSE. The DC approach using uncoupled short trajectories can make contact with traditionally measured experimental rates and folding mechanism when starting from an equilibrated DSE, when the simulation time is long enough to sample the lowest energy states of the unfolded basin and the simulated free-energy surface is correct. However, the DC paradigm, together with faster time-resolved and single-molecule experiments, can also reveal the breakdown in the two-state approximation due to observation of folding events from higher energy subpopulations in the DSE.

  3. Reduced photoinactivation of 10-dodecyl acridine orange-sensitized yeast cells at high fluence rates measurements and computer simulations

    NARCIS (Netherlands)

    Keij, J.F.; Jansen, J.Th.M.; Schultz, F.W.; Visser, J.W.M.

    1994-01-01

    During the development of a photodamage cell sorter several photosensitizers were tested for their ability to photoinactivate more than 90% of the sensitized cells after a brief irradiation with a fluence of 10 kJ/m2. In pilot experiments, yeast cells sensitized with 10-dodecyl acridine orange (DAO)

  4. Denaturing gradient gel electrophoresis profiling of bacterial communities composition in Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Singh, S.K.; Ramaiah, N.

    Denaturing gradient gel electrophoresis (DGGE) was used to elucidate spatial and temporal variations in bacterial community composition (BCC) from four locations along the central west coast of India. DNA extracts from 36 water samples collected...

  5. Streptokinase Recovery by Cross-Flow Microfiltration: Study of Enzyme Denaturation

    National Research Council Canada - National Science Library

    HERNANDEZ-PINZON, Inmaculada; MILLAN, Francisco; BAUTISTA, Juan

    1997-01-01

    ...% remained in the retentate. Immunological experiments using polyclonal antibodies against SK have demonstrated that SK activity loss during CFMF processes could be related to denaturation of SK, forming molecules of lower or no activity...

  6. Single molecule study of the DNA denaturation phase transition in the force-torsion space

    CERN Document Server

    Salerno, D; Mai, I; Brogioli, D; Ziano, R; Cassina, V; Mantegazza, F

    2012-01-01

    We use the "magnetic tweezers" technique to reveal the structural transitions that DNA undergoes in the force-torsion space. In particular, we focus on regions corresponding to negative supercoiling. These regions are characterized by the formation of so-called denaturation bubbles, which have an essential role in the replication and transcription of DNA. We experimentally map the region of the force-torsion space where the denaturation takes place. We observe that large fluctuations in DNA extension occur at one of the boundaries of this region, i.e., when the formation of denaturation bubbles and of plectonemes are competing. To describe the experiments, we introduce a suitable extension of the classical model. The model correctly describes the position of the denaturation regions, the transition boundaries, and the measured values of the DNA extension fluctuations.

  7. Effect of mechanical denaturation on surface free energy of protein powders

    OpenAIRE

    Mohammad, Mohammad Amin; Grimsey, Ian M.; Forbes, Robert T.; Blagbrough, Ian S; Barbara R. Conway

    2016-01-01

    Globular proteins are important both as therapeutic agents and excipients. However, their fragile native\\ud conformations can be denatured during pharmaceutical processing, which leads to modification of\\ud the surface energy of their powders and hence their performance. Lyophilized powders of hen eggwhite\\ud lysozyme and �-galactosidase from Aspergillus oryzae were used as models to study the effects\\ud of mechanical denaturation on the surface energies of basic and acidic protein powders, r...

  8. Thermal denaturation behavior of collagen fibrils in wet and dry environment.

    Science.gov (United States)

    Suwa, Yosuke; Nam, Kwangwoo; Ozeki, Kazuhide; Kimura, Tsuyoshi; Kishida, Akio; Masuzawa, Toru

    2016-04-01

    We have developed a new minimally invasive technique--integrated low-level energy adhesion technique (ILEAT)--which uses heat, pressure, and low-frequency vibrations for binding living tissues. Because the adhesion mechanism of the living tissues is not fully understood, we investigated the effect of thermal energy on the collagen structure in living tissues using ILEAT. To study the effect of thermal energy and heating time on the structure of the collagen fibril, samples were divided in two categories-wet and dry. Further, atomic force microscopy was used to analyze the collagen fibril structure before and after heating. Results showed that collagen fibrils in water denatured after 1 minute at temperatures higher than 80 °C, while partial denaturation was observed at temperatures of 80 °C and a heating time of 1 min. Furthermore, complete denaturation was achieved after 90 min, suggesting that the denaturation rate is temperature and time dependent. Moreover, the collagen fibrils in dry condition maintained their native structure even after being heated to 120 °C for 90 min in the absence of water, which specifically suppressed denaturation. However, partial denaturation of collagen fibrils could not be prevented, because this determines the adhesion between the collagen molecules, and stabilizes tissue bonding.

  9. Interim assessment of the denatured /sup 233/U fuel cycle: feasibility and nonproliferation characteristics

    Energy Technology Data Exchange (ETDEWEB)

    Abbott, L.S.; Bartine, D.E.; Burns, T.J. (eds.)

    1978-12-01

    A fuel cycle that employs /sup 233/U denatured with /sup 238/U and mixed with thorium fertile material is examined with respect to its proliferation-resistance characteristics and its technical and economic feasibility. The rationale for considering the denatured /sup 233/U fuel cycle is presented, and the impact of the denatured fuel on the performance of Light-Water Reactors, Spectral-Shift-Controlled Reactors, Gas-Cooled Reactors, Heavy-Water Reactors, and Fast Breeder Reactors is discussed. The scope of the R, D and D programs to commercialize these reactors and their associated fuel cycles is also summarized and the resource requirements and economics of denatured /sup 233/U cycles are compared to those of the conventional Pu/U cycle. In addition, several nuclear power systems that employ denatured /sup 233/U fuel and are based on the energy center concept are evaluated. Under this concept, dispersed power reactors fueled with denatured or low-enriched uranium fuel are supported by secure energy centers in which sensitive activities of the nuclear cycle are performed. These activities include /sup 233/U production by Pu-fueled transmuters (thermal or fast reactors) and reprocessing. A summary chapter presents the most significant conclusions from the study and recommends areas for future work.

  10. Effects of protein and phosphate buffer concentrations on thermal denaturation of lysozyme analyzed by isoconversional method.

    Science.gov (United States)

    Cao, X M; Tian, Y; Wang, Z Y; Liu, Y W; Wang, C X

    2016-07-03

    Thermal denaturation of lysozymes was studied as a function of protein concentration, phosphate buffer concentration, and scan rate using differential scanning calorimetry (DSC), which was then analyzed by the isoconversional method. The results showed that lysozyme thermal denaturation was only slightly affected by the protein concentration and scan rate. When the protein concentration and scan rate increased, the denaturation temperature (Tm) also increased accordingly. On the contrary, the Tm decreased with the increase of phosphate buffer concentration. The denaturation process of lysozymes was accelatated and the thermal stability was reduced with the increase of phosphate concentration. One part of degeneration process was not reversible where the aggregation occurred. The other part was reversible. The apparent activation energy (Ea) was computed by the isoconversional method. It decreased with the increase of the conversion ratio (α). The observed denaturation process could not be described by a simple reaction mechanism. It was not a process involving 2 standard reversible states, but a multi-step process. The new opportunities for investigating the kinetics process of protein denaturation can be supplied by this novel isoconversional method.

  11. Effect of mechanical denaturation on surface free energy of protein powders.

    Science.gov (United States)

    Mohammad, Mohammad Amin; Grimsey, Ian M; Forbes, Robert T; Blagbrough, Ian S; Conway, Barbara R

    2016-10-01

    Globular proteins are important both as therapeutic agents and excipients. However, their fragile native conformations can be denatured during pharmaceutical processing, which leads to modification of the surface energy of their powders and hence their performance. Lyophilized powders of hen egg-white lysozyme and β-galactosidase from Aspergillus oryzae were used as models to study the effects of mechanical denaturation on the surface energies of basic and acidic protein powders, respectively. Their mechanical denaturation upon milling was confirmed by the absence of their thermal unfolding transition phases and by the changes in their secondary and tertiary structures. Inverse gas chromatography detected differences between both unprocessed protein powders and the changes induced by their mechanical denaturation. The surfaces of the acidic and basic protein powders were relatively basic, however the surface acidity of β-galactosidase was higher than that of lysozyme. Also, the surface of β-galactosidase powder had a higher dispersive energy compared to lysozyme. The mechanical denaturation decreased the dispersive energy and the basicity of the surfaces of both protein powders. The amino acid composition and molecular conformation of the proteins explained the surface energy data measured by inverse gas chromatography. The biological activity of mechanically denatured protein powders can either be reversible (lysozyme) or irreversible (β-galactosidase) upon hydration. Our surface data can be exploited to understand and predict the performance of protein powders within pharmaceutical dosage forms. Copyright © 2016 Elsevier B.V. All rights reserved.

  12. Biophysical analysis of phaseolin denaturation induced by urea, guanidinium chloride, pH, and temperature.

    Science.gov (United States)

    Dyer, J M; Nelson, J W; Murai, N

    1992-06-01

    The structural stability of phaseolin was determined by using absorbance, circular dichroism (CD), fluorescence emission, and fluorescence polarization anisotropy to monitor denaturation induced by urea, guanidinium chloride (GdmCl), pH changes, increasing temperature, or a combination thereof. Initial results indicated that phaseolin remained folded to a similar extent in the presence or absence of 6.0 M urea or GdmCl at room temperature. In 6.0 M GdmCl, phaseolin denatures at approximately 65 degrees C when probed with absorbance, CD, and fluorescence polarization anisotropy. The transition occurs at lower temperatures by decreasing pH. Kinetic measurements of denaturation using CD indicated that the denaturation is slow below 55 degrees C and is associated with an activation energy of 52 kcal/mol in 6.0 M GdmCl. In addition, kinetic measurement using fluorescence emission indicated that the single tryptophan residue was sensitive to at least two steps of the denaturation process. The fluorescence emission appeared to reflect some other structural perturbation than protein denaturation, as fluorescence inflection occurred approximately 5 degrees C prior to the changes observed in absorbance, CD, and fluorescence polarization anisotropy.

  13. Calcium Binding and Disulfide Bonds Regulate the Stability of Secretagogin towards Thermal and Urea Denaturation

    Science.gov (United States)

    Weiffert, Tanja; Ní Mhurchú, Niamh; O’Connell, David; Linse, Sara

    2016-01-01

    Secretagogin is a calcium-sensor protein with six EF-hands. It is widely expressed in neurons and neuro-endocrine cells of a broad range of vertebrates including mammals, fishes and amphibia. The protein plays a role in secretion and interacts with several vesicle-associated proteins. In this work, we have studied the contribution of calcium binding and disulfide-bond formation to the stability of the secretagogin structure towards thermal and urea denaturation. SDS-PAGE analysis of secretagogin in reducing and non-reducing conditions identified a tendency of the protein to form dimers in a redox-dependent manner. The denaturation of apo and Calcium-loaded secretagogin was studied by circular dichroism and fluorescence spectroscopy under conditions favoring monomer or dimer or a 1:1 monomer: dimer ratio. This analysis reveals significantly higher stability towards urea denaturation of Calcium-loaded secretagogin compared to the apo protein. The secondary and tertiary structure of the Calcium-loaded form is not completely denatured in the presence of 10 M urea. Reduced and Calcium-loaded secretagogin is found to refold reversibly after heating to 95°C, while both oxidized and reduced apo secretagogin is irreversibly denatured at this temperature. Thus, calcium binding greatly stabilizes the structure of secretagogin towards chemical and heat denaturation. PMID:27812162

  14. Tissue sealing device associated thermal spread: a comparison of histologic methods for detecting adventitial collagen denaturation

    Science.gov (United States)

    Jones, Ryan M.; Grisez, Brian T.; Thomas, Aaron C.; Livengood, Ryan H.; Coad, James E.

    2013-02-01

    Thermal spread (thermal tissue damage) results from heat conduction through the tissues immediately adjacent to a hyperthermic tissue sealing device. The extent of such heat conduction can be assessed by the detection of adventitial collagen denaturation. Several histologic methods have been reported to measure adventitial collagen denaturation as a marker of thermal spread. This study compared hematoxylin and eosin staining, Gomori trichrome staining and loss of collagen birefringence for the detection of collagen denaturation. Twenty-eight ex vivo porcine carotid arteries were sealed with a commercially available, FDA-approved tissue sealing device. Following formalin fixation and paraffin embedding, two 5-micron tissue sections were hematoxylin and eosin and Gomori trichrome stained. The hematoxylin and eosin-stained section was evaluated by routine bright field microscopy and under polarized light. The trichromestained section was evaluated by routine bright field microscopy. Radial and midline adventitial collagen denaturation measurements were made for both the top and bottom jaw sides of each seal. The adventitial collagen denaturation lengths were determined using these three methods and statistically compared. The results showed that thermal spread, as represented by histologically detected collagen denaturation, is technique dependent. In this study, the trichrome staining method detected significantly less thermal spread than the hematoxylin and eosin staining and birefringence methods. Of the three methods, hematoxylin and eosin staining provided the most representative results for true thermal spread along the adjacent artery.

  15. Diclofenac sodium overdose

    Science.gov (United States)

    ... page: //medlineplus.gov/ency/article/002630.htm Diclofenac sodium overdose To use the sharing features on this page, please enable JavaScript. Diclofenac sodium is a prescription medicine used to relieve pain ...

  16. Naproxen sodium overdose

    Science.gov (United States)

    ... page: //medlineplus.gov/ency/article/002507.htm Naproxen sodium overdose To use the sharing features on this page, please enable JavaScript. Naproxen sodium is a nonsteroidal anti-inflammatory drug (NSAID) used ...

  17. Docusate Sodium and Pregnancy

    Science.gov (United States)

    ... live chat Live Help Fact Sheets Share Docusate Sodium Friday, 01 April 2016 In every pregnancy, a ... This sheet talks about whether exposure to docusate sodium may increase the risk for birth defects over ...

  18. Sodium carbonate poisoning

    Science.gov (United States)

    Sodium carbonate (known as washing soda or soda ash) is a chemical found in many household and ... products. This article focuses on poisoning due to sodium carbonate. This article is for information only. Do ...

  19. Sodium Ferric Gluconate Injection

    Science.gov (United States)

    Sodium ferric gluconate injection is used to treat iron-deficiency anemia (a lower than normal number of ... are also receiving the medication epoetin (Epogen, Procrit). Sodium ferric gluconate injection is in a class of ...

  20. Denaturant-Dependent Conformational Changes in a [beta]-Trefoil Protein: Global and Residue-Specific Aspects of an Equilibrium Denaturation Process

    Energy Technology Data Exchange (ETDEWEB)

    Latypov, Ramil F.; Liu, Dingjiang; Jacob, Jaby; Harvey, Timothy S.; Bondarenko, Pavel V.; Kleemann, Gerd R.; Brems, David N.; Raibekas, Andrei A.; (Amgen)

    2010-01-12

    Conformational properties of the folded and unfolded ensembles of human interleukin-1 receptor antagonist (IL-1ra) are strongly denaturant-dependent as evidenced by high-resolution two-dimensional nuclear magnetic resonance (NMR), limited proteolysis, and small-angle X-ray scattering (SAXS). The folded ensemble was characterized in detail in the presence of different urea concentrations by 1H-15N HSQC NMR. The {beta}-trefoil fold characteristic of native IL-1ra was preserved until the unfolding transition region beginning at 4 M urea. At the same time, a subset of native resonances disappeared gradually starting at low denaturant concentrations, indicating noncooperative changes in the folded state. Additional evidence of structural perturbations came from the chemical shift analysis, nonuniform and bell-shaped peak intensity profiles, and limited proteolysis. In particular, the following nearby regions of the tertiary structure became progressively destabilized with increasing urea concentrations: the {beta}-hairpin interface of trefoils 1 and 2 and the H2a-H2 helical region. These regions underwent small-scale perturbations within the native baseline region in the absence of populated molten globule-like states. Similar regions were affected by elevated temperatures known to induce irreversible aggregation of IL-1ra. Further evidence of structural transitions invoking near-native conformations came from an optical spectroscopy analysis of its single-tryptophan variant W17A. The increase in the radius of gyration was associated with a single equilibrium unfolding transition in the case of two different denaturants, urea and guanidine hydrochloride (GuHCl). However, the compactness of urea- and GuHCl-unfolded molecules was comparable only at high denaturant concentrations and deviated under less denaturing conditions. Our results identified the role of conformational flexibility in IL-1ra aggregation and shed light on the nature of structural transitions within the

  1. Mg2+-induced vesicles of tetradecyldimethylamine oxide and magnesium dodecyl sulfate.

    Science.gov (United States)

    Teng, Minmin; Song, Aixin; Hao, Jingcheng

    2009-10-15

    A Mg2+-induced vesicle phase was prepared from a mixture of tetradecyldimethylamine oxide (C14DMAO) and magnesium dodecyl sulfate [Mg(DS)2] in aqueous solution. Study of the phase behavior shows that at the appropriate mixing ratios, Mg2+-ligand coordination between C14DMAO and Mg(DS)2 results in the formation of molecular bilayers, in which Mg2+ can firmly bind to the head groups of the two surfactants. The area of the head group can be reduced because of the complexation. In this case, no counterions exist in aqueous solution because of the fixation of Mg2+ ions to the bilayer membranes. Therefore, the charges of the bilayer membranes are not shielded by salts. The birefringent solutions of Mg(DS)2 and C14DMAO mixtures consist of vesicles which were determined by transmission electron microscopy (TEM) images and rheological measurements. Magnesium oxide (MgO) nanoplates were obtained via the decomposition of Mg(OH)2 which were synthesized in Mg2+-induced vesicle phase which was used as the microreactor under the existence of ammonia hydroxide. The morphologies and structures of the obtained MgO nanoplates have been characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results indicate that the crystal growth is along the (111) direction which can be affected by the presence of a vesicle phase having a fixation of Mg2+ ions to the bilayer membranes.

  2. Aggregation behavior modulation of 1-dodecyl-3-methylimidazolium bromide by organic solvents in aqueous solution.

    Science.gov (United States)

    Wang, Jianji; Zhang, Lamei; Wang, Huiyong; Wu, Changzeng

    2011-05-05

    Material preparation in ionic liquids and environmental pollution control by ionic liquids are often closely dependent on the aggregation behavior of ionic liquids in solution. In the present work, conductivity, fluorescence probe, and dynamic light scattering techniques have been used to study the effect of organic solvents on the aggregation behavior of 1-dodecyl-3-methylimidazolium bromide in water. It was shown that the critical aggregation concentration (CAC), the ionization degree of the aggregates (α), and the standard Gibbs energy of aggregation (ΔG(m)°) of the ionic liquid increase, while its aggregation number (N(agg)) and aggregates' size decrease with increasing concentration of organic additives in water. These results have been discussed from the favorable interactions of alkyl chain of the ionic liquid with the mixed solvents. It is suggested that the solvophobic parameter, characterized quantitatively by Gibbs energy of transfer of hydrocarbon from gas into a given solvent, can be used to account for the effect of organic additives on the formation and growth of the ionic liquid aggregates in water. Aggregation behavior of ionic liquids in aqueous organic solutions can be modulated simply by the solvophobic parameters of hydrocarbon in the mixed solvents.

  3. Sodium sieving in children.

    NARCIS (Netherlands)

    Rusthoven, E.; Krediet, R.T.; Willems, H.L.; Monnens, L.A.H.; Schroder, C.H.

    2005-01-01

    Sodium sieving is a consequence of dissociation between the amount of water and sodium transported over the peritoneal membrane. This dissociation occurs in the presence of aquaporin-mediated water transport. Sieving of sodium can be used as a rough measure for aquaporin-mediated water transport. Ic

  4. Correlated parameter fit of arrhenius model for thermal denaturation of proteins and cells.

    Science.gov (United States)

    Qin, Zhenpeng; Balasubramanian, Saravana Kumar; Wolkers, Willem F; Pearce, John A; Bischof, John C

    2014-12-01

    Thermal denaturation of proteins is critical to cell injury, food science and other biomaterial processing. For example protein denaturation correlates strongly with cell death by heating, and is increasingly of interest in focal thermal therapies of cancer and other diseases at temperatures which often exceed 50 °C. The Arrhenius model is a simple yet widely used model for both protein denaturation and cell injury. To establish the utility of the Arrhenius model for protein denaturation at 50 °C and above its sensitivities to the kinetic parameters (activation energy E a and frequency factor A) were carefully examined. We propose a simplified correlated parameter fit to the Arrhenius model by treating E a, as an independent fitting parameter and allowing A to follow dependently. The utility of the correlated parameter fit is demonstrated on thermal denaturation of proteins and cells from the literature as a validation, and new experimental measurements in our lab using FTIR spectroscopy to demonstrate broad applicability of this method. Finally, we demonstrate that the end-temperature within which the denaturation is measured is important and changes the kinetics. Specifically, higher E a and A parameters were found at low end-temperature (50 °C) and reduce as end-temperatures increase to 70 °C. This trend is consistent with Arrhenius parameters for cell injury in the literature that are significantly higher for clonogenics (45-50 °C) vs. membrane dye assays (60-70 °C). Future opportunities to monitor cell injury by spectroscopic measurement of protein denaturation are discussed.

  5. Development of novel short-term heating angioplasty: thermal denaturation dynamics of collagen in artery wall

    Science.gov (United States)

    Shimazaki, N.; Tokunaga, H.; Katou, Y.; Hayashi, T.; Arai, T.

    2009-02-01

    We have studied to develop the new thermal angioplasty methodology, photo-thermo dynamic balloon angioplasty (PTDBA), which provides artery dilatation with short-term (collagen in artery media may be the important factor to attain sufficient artery dilatation for the PTDBA. In order to predict the optimum heating condition i.e. the balloon temperature and heating duration, we investigated the thermal denaturation dynamics of artery collagen in ex vivo. The extracted fresh porcine carotid artery was used. The temperature-dependent light scattering property and mechanical property of the artery specimen were simultaneously measured during artery temperature rising by specially made setup to assess the denaturation of arterial collagen. The change rate of the backscattered light intensity from the artery specimen; I(T)/I0 with 633nm was measured to evaluate the artery scattering property change with the thermal denaturation. The artery specimen was heated from 25°C to 80°C with constant temperature rising rate of 3°C/min. The measured I(T)/I0 was suddenly increased over 48°C. This boundary temperature might be the initiation temperature of the arterial collagen denaturation. We defined the variation of the I(T)/I0 as the collagen denaturation ratio, and calculated the reactive enthalpy by the chemical equilibrium theory. Since the calculated enthalpy was similar to the enthalpy in literature report, the variety of I(T)/I0 during the temperature rising might be attributed to the collagen conformational change due to the denaturation. In terms of the artery internal force measurement, the artery force was decreased with increasing of the artery temperature up to 65°C (i.e. softening), and increased over 65°C (i.e. shrinkage). We confirmed that the changes of the backscattered light (at 633nm in wavelength) from the artery might represent the artery collagen thermal denaturation degree.

  6. Effect of high-pressure treatment on denaturation of bovine lactoferrin and lactoperoxidase.

    Science.gov (United States)

    Mazri, C; Sánchez, L; Ramos, S J; Calvo, M; Pérez, M D

    2012-02-01

    Lactoferrin and lactoperoxidase are whey proteins with biological properties that may provide health benefits to consumers. These properties are vulnerable to potentially denaturing conditions during processing. High-pressure treatment is an appealing alternative to the traditional heat processing of foods because it exerts an antimicrobial effect without changing the sensory and nutritional quality of foods. In this work, the effect of high-pressure treatment on the denaturation of lactoferrin and lactoperoxidase present in skim milk and whey, and as isolated proteins in buffer, was studied over a pressure range of 450 to 700 MPa at 20°C. Denaturation of lactoferrin was measured by the loss of reactivity with their specific antibodies using a sandwich ELISA. Denaturation of lactoperoxidase was determined by measuring the loss of enzymatic activity using a spectrophotometric technique. No substantial inactivation of lactoperoxidase was observed in any treatment assayed. The concentration of the residual immunoreactive lactoferrin after each pressure treatment was determined, and the data were subjected to kinetic analysis to obtain D and Z values. Denaturation of lactoferrin increased with pressure and holding time, and D values were lower when lactoferrin was treated in whey than in milk, and lower in both whey and milk than in phosphate buffer. Thus, protein is denatured more slowly in buffer and in milk than in whey. Denaturation of lactoferrin in the 3 media was found to follow a reaction order of n=1.5. Volumes of activation of about -34.77, -24.35, and -24.09 mL/mol were obtained for lactoferrin treated in skim milk, whey, and buffer, respectively, indicating a decrease in protein volume under pressure.

  7. MicroRNA-23b Inhibits the Proliferation and Migration of Heat-Denatured Fibroblasts by Targeting Smad3.

    Directory of Open Access Journals (Sweden)

    Xipeng Zhang

    Full Text Available Skin grafting with the preservation of denatured dermis is a novel strategy for the treatment of burn-injured skin. Denatured dermis has the ability to restore to the morphology and function of normal skin, but the underlying molecular mechanism is elusive. MicroRNAs (miRNA are small noncoding RNAs and regulate normal physiology as well as disease development. In this study, we assessed the potential role of miRNA-23b (miR-23b in the regulation of cell proliferation and migration of heat-denatured fibroblasts and identified the underlying mechanism.The expression of miR-23b in denatured dermis and heat-denatured fibroblasts was detected by quantitative real-time polymerase chain reaction (RT-PCR. The effects of miR-23b on cell proliferation and migration of heat-denatured fibroblasts were assessed by transient transfection of miR-23b mimics and inhibitor. The target gene of miR-23b and the downstream pathway were further investigated.miR-23b was downregulated in denatured dermis and heat-denatured fibroblasts. Downregulation of miR-23b dramatically promoted the proliferation and migration of heat-denatured fibroblasts. Subsequent analyses demonstrated that Smad3 was a direct and functional target of miR-23b in heat-denatured fibroblasts, which was validated by the dual luciferase reporter assay. Moreover, immunohistochemistry analysis showed that denatured dermis from rats displayed enhanced staining of Smad3. In addition, miR-23b modulated denatured dermis by activating the Notch1 and TGF-β signaling pathways.Our findings suggest that downregulation of miR-23b contributes to the recovery of denatured dermis, which may be valuable for treatment of skin burns.

  8. Sodium in feline nutrition.

    Science.gov (United States)

    Nguyen, P; Reynolds, B; Zentek, J; Paßlack, N; Leray, V

    2016-08-23

    High sodium levels in cat food have been controversial for a long time. Nonetheless, high sodium levels are used to enhance water intake and urine volume, with the main objective of reducing the risk of urolithiasis. This article is a review of current evidence of the putative risks and benefits of high dietary sodium levels. Its secondary aim is to report a possible safe upper limit (SUL) for sodium intake. The first part of the manuscript is dedicated to sodium physiology, with a focus on the mechanisms of sodium homeostasis. In this respect, there is only few information regarding possible interactions with other minerals. Next, the authors address how sodium intake affects sodium balance; knowledge of these effects is critical to establish recommendations for sodium feed content. The authors then review the consequences of changes in sodium intake on feline health, including urolithiasis, blood pressure changes, cardiovascular alterations and kidney disease. According to recent, long-term studies, there is no evidence of any deleterious effect of dietary sodium levels as high as 740 mg/MJ metabolizable energy, which can therefore be considered the SUL based on current knowledge.

  9. Alcohol-induced structural transitions in the acid-denatured Bacillus licheniformis α-amylase

    Directory of Open Access Journals (Sweden)

    Adyani Azizah Abd Halim

    2017-01-01

    Full Text Available Alcohol-induced structural changes in the acid-denatured Bacillus licheniformis α-amylase (BLA at pH 2.0 were studied by far-ultra violet circular dichroism, intrinsic, three-dimensional and 8-anilino-1-naphthalene sulfonic acid (ANS fluorescence, acrylamide quenching and thermal denaturation. All the alcohols used in this study produced partial refolding in the acid-denatured BLA as evident from the increased mean residue ellipticity at 222 nm, increased intrinsic fluorescence and decreased ANS fluorescence. The order of effectiveness of these alcohols to induce a partially folded state of BLA was found to be: 2,2,2-trifluoroethanol/tert-butanol > 1-propanol/2-propanol > 2-chloroethanol > ethanol > methanol. Three-dimensional fluorescence and acrylamide quenching results obtained in the presence of 5.5 M tert-butanol also suggested formation of a partially folded state in the acid-denatured BLA. However, 5.5 M tert-butanol-induced state of BLA showed a non-cooperative thermal transition. All these results suggested formation of a partially folded state of the acid-denatured BLA in the presence of these alcohols. Furthermore, their effectiveness was found to be guided by their chain length, position of methyl groups and presence of the substituents.

  10. Drying and denaturation characteristics of whey protein isolate in the presence of lactose and trehalose.

    Science.gov (United States)

    Haque, M Amdadul; Chen, Jie; Aldred, Peter; Adhikari, Benu

    2015-06-15

    The denaturation kinetics of whey protein isolate (WPI), in the presence and absence of lactose and trehalose, was quantified in a convective air-drying environment. Single droplets of WPI, WPI-lactose and WPI-trehalose were dried in conditioned air (2.5% RH, 0.5m/s air velocity) at two temperatures (65°C and 80°C) for 500s. The initial solid concentration of these solutions was 10% (w/v) in all the samples. Approximately 68% of WPI was denatured when it was dried in the absence of sugars. Addition of 20% trehalose prevented the irreversible denaturation of WPI at both temperatures. Thirty percent lactose was required to prevent denaturation of WPI at 65°C and the same amount of lactose protected only 70% of WPI from denaturation at 80°C. The secondary structures of WPI were found to be altered by the drying-induced stresses, even in the presence of 20% trehalose and 30% lactose.

  11. Denaturation of milk proteins and their influence on the yield of fresh cheese

    Directory of Open Access Journals (Sweden)

    Ana Mejía-López

    2017-03-01

    Full Text Available To determine the denaturation of milk proteins by the effects of heat treatment on pasteurization and to establish their influence on the yield of the fresh cheese manufactured, 20 laboratory- scale controlled trials and 40 plant productions were made. Crude and treated milk was used at 65 ° C for 30 minutes, 72 ° C for 15 seconds and boiled for 2 seconds, and the protein was quantified in milk to calculate percent denaturation. In the cheese the moisture content was determined and the amount of cheese obtained was quantified. The data were processed by Tukey's mean analysis (p> 0.05. The results at the laboratory level showed that the increase in temperature caused higher denaturation of the proteins, a higher yield and an increase in moisture in the cheese compared to that obtained with raw milk. However, statistically the results showed that the heat treatment does influence the denaturation of the proteins but not the performance of the cheese. The results obtained in the factory investigation revealed that at 65 and 72 ° C the yield decreases relative to the production with raw milk, but statistically does not present significant differences in the yield, concluding that the pasteurization at different temperatures denature the protein But does not influence the performance of fresh processed cheese.

  12. A versatile protein microarray platform enabling antibody profiling against denatured proteins.

    Science.gov (United States)

    Wang, Jie; Barker, Kristi; Steel, Jason; Park, Jin; Saul, Justin; Festa, Fernanda; Wallstrom, Garrick; Yu, Xiaobo; Bian, Xiaofang; Anderson, Karen S; Figueroa, Jonine D; LaBaer, Joshua; Qiu, Ji

    2013-06-01

    We aim to develop a protein microarray platform capable of presenting both natural and denatured forms of proteins for antibody biomarker discovery. We will further optimize plasma screening protocols to improve detection. We developed a new covalent capture protein microarray chemistry using HaloTag fusion proteins and ligand. To enhance protein yield, we used HeLa cell lysate as an in vitro transcription translation (IVTT) system. Escherichia coli lysates were added to the plasma blocking buffer to reduce nonspecific background. These protein microarrays were probed with plasma samples and autoantibody responses were quantified and compared with or without denaturing buffer treatment. We demonstrated that protein microarrays using the covalent attachment chemistry endured denaturing conditions. Blocking with E. coli lysates greatly reduced the background signals and expression with IVTT based on HeLa cell lysates significantly improved the antibody signals on protein microarrays probed with plasma samples. Plasma samples probed on denatured protein arrays produced autoantibody profiles distinct from those probed on natively displayed proteins. This versatile protein microarray platform allows the display of both natural and denatured proteins, offers a new dimension to search for disease-specific antibodies, broadens the repertoire of potential biomarkers, and will potentially yield clinical diagnostics with greater performance. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Comparison of chemical and thermal protein denaturation by combination of computational and experimental approaches. II

    Science.gov (United States)

    Wang, Qian; Christiansen, Alexander; Samiotakis, Antonios; Wittung-Stafshede, Pernilla; Cheung, Margaret S.

    2011-11-01

    Chemical and thermal denaturation methods have been widely used to investigate folding processes of proteins in vitro. However, a molecular understanding of the relationship between these two perturbation methods is lacking. Here, we combined computational and experimental approaches to investigate denaturing effects on three structurally different proteins. We derived a linear relationship between thermal denaturation at temperature Tb and chemical denaturation at another temperature Tu using the stability change of a protein (ΔG). For this, we related the dependence of ΔG on temperature, in the Gibbs-Helmholtz equation, to that of ΔG on urea concentration in the linear extrapolation method, assuming that there is a temperature pair from the urea (Tu) and the aqueous (Tb) ensembles that produces the same protein structures. We tested this relationship on apoazurin, cytochrome c, and apoflavodoxin using coarse-grained molecular simulations. We found a linear correlation between the temperature for a particular structural ensemble in the absence of urea, Tb, and the temperature of the same structural ensemble at a specific urea concentration, Tu. The in silico results agreed with in vitro far-UV circular dichroism data on apoazurin and cytochrome c. We conclude that chemical and thermal unfolding processes correlate in terms of thermodynamics and structural ensembles at most conditions; however, deviations were found at high concentrations of denaturant.

  14. Polar or apolar--the role of polarity for urea-induced protein denaturation.

    Directory of Open Access Journals (Sweden)

    Martin C Stumpe

    2008-11-01

    Full Text Available Urea-induced protein denaturation is widely used to study protein folding and stability; however, the molecular mechanism and driving forces of this process are not yet fully understood. In particular, it is unclear whether either hydrophobic or polar interactions between urea molecules and residues at the protein surface drive denaturation. To address this question, here, many molecular dynamics simulations totalling ca. 7 micros of the CI2 protein in aqueous solution served to perform a computational thought experiment, in which we varied the polarity of urea. For apolar driving forces, hypopolar urea should show increased denaturation power; for polar driving forces, hyperpolar urea should be the stronger denaturant. Indeed, protein unfolding was observed in all simulations with decreased urea polarity. Hyperpolar urea, in contrast, turned out to stabilize the native state. Moreover, the differential interaction preferences between urea and the 20 amino acids turned out to be enhanced for hypopolar urea and suppressed (or even inverted for hyperpolar urea. These results strongly suggest that apolar urea-protein interactions, and not polar interactions, are the dominant driving force for denaturation. Further, the observed interactions provide a detailed picture of the underlying molecular driving forces. Our simulations finally allowed characterization of CI2 unfolding pathways. Unfolding proceeds sequentially with alternating loss of secondary or tertiary structure. After the transition state, unfolding pathways show large structural heterogeneity.

  15. Experimental and Modelling Study of the Denaturation of Milk Protein by Heat Treatment

    Science.gov (United States)

    Qian, Fang; Sun, Jiayue; Cao, Di; Tuo, Yanfeng; Jiang, Shujuan; Mu, Guangqing

    2017-01-01

    Heat treatment of milk aims to inhibit the growth of microbes, extend the shelf-life of products and improve the quality of the products. Heat treatment also leads to denaturation of whey protein and the formation of whey protein-casein polymer, which has negative effects on milk product. Hence the milk heat treatment conditions should be controlled in milk processing. In this study, the denaturation degree of whey protein and the combination degree of whey protein and casein when undergoing heat treatment were also determined by using the Native-PAGE and SDS-PAGE analysis. The results showed that the denaturation degree of whey protein and the combination degree of whey protein with casein extended with the increase of the heat-treated temperature and time. The effects of the heat-treated temperature and heat-treated time on the denaturation degree of whey protein and on the combination degree of whey protein and casein were well described using the quadratic regression equation. The analysis strategy used in this study reveals an intuitive and effective measure of the denaturation degree of whey protein, and the changes of milk protein under different heat treatment conditions efficiently and accurately in the dairy industry. It can be of great significance for dairy product proteins following processing treatments applied for dairy product manufacturing. PMID:28316470

  16. High pressure inactivation of relevant target microorganisms in poultry meat products and the evaluation of pressure-induced protein denaturation of marinated poultry under different high pressure treatments

    Science.gov (United States)

    Schmidgall, Johanna; Hertel, Christian; Bindrich, Ute; Heinz, Volker; Toepfl, Stefan

    2011-03-01

    In this study, the possibility of extending shelf life of marinated poultry meat products by high pressure processing was evaluated. Relevant spoilage and pathogenic strains were selected and used as target microorganisms (MOs) for challenge experiments. Meat and brine were inoculated with MOs and treated at 450 MPa, 4 °C for 3 min. The results of inactivation show a decreasing pressure tolerance in the series Lactobacillus > Arcobacter > Carnobacterium > Bacillus cereus > Brochothrix thermosphacta > Listeria monocytogenes. Leuconostoc gelidum exhibited the highest pressure tolerance in meat. A protective effect of poultry meat was found for L. sakei and L. gelidum. In parallel, the influence of different marinade formulations (pH, carbonates, citrates) on protein structure changes during a pressure treatment was investigated. Addition of sodium carbonate shows a protection against denaturation of myofibrillar proteins and provides a maximum water-holding capacity. Caustic marinades allowed a higher retention of product characteristics than low-pH marinades.

  17. Analysis of phosphate-accumulating organisms cultivated under different carbon sources with polymerase chain reaction-denaturing gradient gel electrophoresis assay

    Institute of Scientific and Technical Information of China (English)

    YU Shui-li; LIU Ya-nan; JING Guo-lin; ZHAO Bing-jie; GUO Si-yuan

    2005-01-01

    To investigate the microbial communities of microorganisms cultivated under different carbon sources, three sequencing batch reactors were operated. They were supplied with sewage, glucose and sodium acetate as carbon sources respectively and showed high phosphorus removal performance. The results of denaturing gradient gel electrophoresis(DGGE) of polymerase chain reaction-amplified (PCR) 16S rDNA fragments demonstrated that β-protebacteria, Actinomyces sp. and γ-protebacteria only exited in 1 # reactor. The microbiological diversity of 1 # reactor exceeded the other two reactors. Flavobacterium, Bacillales, Actinomyces, Actinobacteridae and uncultured bacteria(AF527584, AF502204, AY592749, AB076862, AJ619051, AF495454 and AY133070) could be detected in the biological phosphorus removal reactors.

  18. Antibodies with specificity for native and denatured forms of ovalbumin differ in reactivity between enzyme-linked immunosorbent assays

    DEFF Research Database (Denmark)

    Holm, B.E.; Bergmann, A.C.; Hansen, Paul Robert

    2015-01-01

    In this study, polyclonal and monoclonal antibodies to native and denatured chicken ovalbumin (OVA) were produced to compare their dependency on continuous and three-dimensional epitopes. These antibodies were characterized with respect to reactivity to native and denatured OVA by enzyme...... to native OVA reacted strongly with native and denatured OVA in both assays, but did not react with the overlapping peptides. Polyclonal antibodies to denatured OVA reacted strongly with both OVA forms and with several of the overlapping peptides. Monoclonal antibodies to native OVA reacted preferentially...... with three-dimensional epitopes on native OVA and not with denatured OVA. Monoclonal antibodies to denatured OVA showed reactivity to both OVA forms. Two of these monoclonal antibodies, HYB 94-06 and 94-07, showed reactivity to overlapping peptides and their epitopes were identified as flexible structures...

  19. Effects of dodecyl sulfate and nitrate anions on the supercapacitive properties of α-Co(OH){sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Liu, L.; Cheng, J.P., E-mail: chengjp@zju.edu.cn; Zhang, J.; Liu, F.; Zhang, X.B.

    2014-12-05

    Highlights: • DS intercalated α-Co(OH){sub 2} is prepared using a simple and efficient co-precipitation method. • The effects of DS and nitrate anions on the supercapacitive properties of α-Co(OH){sub 2} are studied. • α-Co(OH){sub 2} studied here can be applied as an efficient electrode materials for supercapacitors. - Abstract: Dodecyl sulfate and nitrate intercalated α-Co(OH){sub 2} are prepared by a simple co-precipitation and a subsequent anion-exchange method using hexamethylenetetramine as a hydrolysis agent, which have been confirmed by X-ray diffraction and FTIR analysis. Interlayer spacing of α-Co(OH){sub 2} layers for dodecyl sulfate and nitrate intercalated α-Co(OH){sub 2} is determined to be 12.96 and 8 Å, respectively. Their supercapacitive properties are measured by cyclic voltammetry and galvanostatic charge–discharge tests. The α-Co(OH){sub 2} exhibits a higher specific capacitance and better rate capability after anion exchange from dodecyl sulfate to nitrate with the specific capacitance increasing from 304.4 to 582.7 F g{sup −1} at 1 A g{sup −1}.

  20. Renal sodium handling and sodium sensitivity

    Directory of Open Access Journals (Sweden)

    Alissa A. Frame

    2017-06-01

    Full Text Available The pathophysiology of hypertension, which affects over 1 billion individuals worldwide, involves the integration of the actions of multiple organ systems, including the kidney. The kidney, which governs sodium excretion via several mechanisms including pressure natriuresis and the actions of renal sodium transporters, is central to long term blood pressure regulation and the salt sensitivity of blood pressure. The impact of renal sodium handling and the salt sensitivity of blood pressure in health and hypertension is a critical public health issue owing to the excess of dietary salt consumed globally and the significant percentage of the global population exhibiting salt sensitivity. This review highlights recent advances that have provided new insight into the renal handling of sodium and the salt sensitivity of blood pressure, with a focus on genetic, inflammatory, dietary, sympathetic nervous system and oxidative stress mechanisms that influence renal sodium excretion. Increased understanding of the multiple integrated mechanisms that regulate the renal handling of sodium and the salt sensitivity of blood pressure has the potential to identify novel therapeutic targets and refine dietary guidelines designed to treat and prevent hypertension.

  1. Inhibition of thermal induced protein denaturation of extract/fractions of Withania somnifera and isolated withanolides.

    Science.gov (United States)

    Khan, Murad Ali; Khan, Haroon; Rauf, Abdul; Ben Hadda, Taibi

    2015-01-01

    This study describes the in vitro inhibition of protein denaturation of extract/fractions of Withania somnifera and isolated withanolides including 20β hydroxy-1-oxo(22R)-witha-2,5,24 trienolide (1), (20R,22R-14α,20α)-dihydroxy-1-oxowitha-2,5,16,24 tetraenolide (2). The results showed that the extract/fractions of the plant evoked profound inhibitory effect on thermal-induced protein denaturation. The chloroform fraction caused the most dominant attenuation of 68% at 500 μg/mL. The bioactivity-guided isolation from chloroform fraction led to the isolation of compounds 1 and 2 that showed profound protein inhibition with 78.05% and 80.43% effect at 500 μg/mL and thus strongly complimented the activity of extract/fractions. In conclusion, extract/fractions of W. somnifera possessed strong inhibition of protein denaturation that can be attributed to these isolated withanolides.

  2. Nonsurgical transurethral radiofrequency collagen denaturation: results at three years after treatment.

    Science.gov (United States)

    Elser, Denise M; Mitchell, Gretchen K; Miklos, John R; Nickell, Kevin G; Cline, Kevin; Winkler, Harvey; Wells, W Glen

    2011-01-01

    Objective. To assess treatment efficacy and quality of life in women with stress urinary incontinence 3 years after treatment with nonsurgical transurethral radiofrequency collagen denaturation. Methods. This prospective study included 139 women with stress urinary incontinence due to bladder outlet hypermobility. Radiofrequency collagen denaturation was performed using local anesthesia in an office setting. Assessments included incontinence quality of life (I-QOL) and urogenital distress inventory (UDI-6) instruments. Results. In total, 139 women were enrolled and 136 women were treated (mean age, 47 years). At 36 months, intent-to-treat analysis (n = 139) revealed significant improvements in quality of life. Mean I-QOL score improved 17 points from baseline (P = .0004), while mean UDI-6 score improved (decreased) 19 points (P = .0005). Conclusions. Transurethral collagen denaturation is a low-risk, office-based procedure that results in durable quality-of-life improvements in a significant proportion of women for as long as 3 years.

  3. Stabilizing Effect of Various Polyols on the Native and the Denatured States of Glucoamylase

    Directory of Open Access Journals (Sweden)

    Mohammed Suleiman Zaroog

    2013-01-01

    Full Text Available Different spectral probes were employed to study the stabilizing effect of various polyols, such as, ethylene glycol (EG, glycerol (GLY, glucose (GLC and trehalose (TRE on the native (N, the acid-denatured (AD and the thermal-denatured (TD states of Aspergillus niger glucoamylase (GA. Polyols induced both secondary and tertiary structural changes in the AD state of enzyme as reflected from altered circular dichroism (CD, tryptophan (Trp, and 1-anilinonaphthalene-8-sulfonic acid (ANS fluorescence characteristics. Thermodynamic analysis of the thermal denaturation curve of native GA suggested significant increase in enzyme stability in the presence of GLC, TRE, and GLY (in decreasing order while EG destabilized it. Furthermore, CD and fluorescence characteristics of the TD state at 71°C in the presence of polyols showed greater effectiveness of both GLC and TRE in inducing native-like secondary and tertiary structures compared to GLY and EG.

  4. Gel electrophoresis of DNA partially denatured at the ends: what are the dominant conformations?

    Science.gov (United States)

    Sean, David; Slater, Gary W

    2013-03-01

    Gel electrophoresis of a partially denatured dsDNA fragment is studied using Langevin Dynamics computer simulations. For simplicity, the denatured ssDNA sections are placed at the ends of the fragment in a symmetrical fashion. A squid-like conformation is found to sometimes cause the fragment to completely block in the gel. In fact, this conformation is the principal cause of the steep reduction in mobility observed in the simulations. As the field is increased, it is found that the occurrence of this conformation dominates the migration dynamics. Although the squid conformation seems to be more stable at high fields, the field can eventually force the fragments to thread through the gel pores regardless. We qualitatively explore the behavior of this squid-like conformation across a range of fields and degrees of denaturation, and we discuss the relevance of our findings for TGGE. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. EQUIVALENCY OF FOULING THICKNESS WITH DENATURED Β-LG IN HEATING OF MILK

    Directory of Open Access Journals (Sweden)

    Heriberto Molina-Pérez

    2015-03-01

    Full Text Available This work presents an approach to match the foaling thickness of dairy food and the concentration of denatured β-lg (β-lactoglobuline by a mathematical model. This includes, on the one hand, the dynamic simulation of fouling and, on the other hand, the generation of denatured β-lg under a kinetic model. In both cases a transient energy balance is developed, including the rigorous calculation of the global coefficient, and the properties by the Choi-Okos model. The solution was obtained by a fourth order Runge-Kutta written in Excel’s Macro language Visual Basic. The equivalence concluded with a model obtained by a non-linear multiple regression that relates the concentration of denatured β-lg and the foaling thickness. This methodology is applicable to analysis equipment cleaning in which kinetic cleaning has equality by reduction of the foaling thickness.

  6. Statistical mechanics of the denatured state of a protein using replica-averaged metadynamics.

    Science.gov (United States)

    Camilloni, Carlo; Vendruscolo, Michele

    2014-06-25

    The characterization of denatured states of proteins is challenging because the lack of permanent structure in these states makes it difficult to apply to them standard methods of structural biology. In this work we use all-atom replica-averaged metadynamics (RAM) simulations with NMR chemical shift restraints to determine an ensemble of structures representing an acid-denatured state of the 86-residue protein ACBP. This approach has enabled us to reach convergence in the free energy landscape calculations, obtaining an ensemble of structures in relatively accurate agreement with independent experimental data used for validation. By observing at atomistic resolution the transient formation of native and non-native structures in this acid-denatured state of ACBP, we rationalize the effects of single-point mutations on the folding rate, stability, and transition-state structures of this protein, thus characterizing the role of the unfolded state in determining the folding process.

  7. Nonsurgical Transurethral Radiofrequency Collagen Denaturation: Results at Three Years after Treatment

    Directory of Open Access Journals (Sweden)

    Denise M. Elser

    2011-01-01

    Full Text Available Objective. To assess treatment efficacy and quality of life in women with stress urinary incontinence 3 years after treatment with nonsurgical transurethral radiofrequency collagen denaturation. Methods. This prospective study included 139 women with stress urinary incontinence due to bladder outlet hypermobility. Radiofrequency collagen denaturation was performed using local anesthesia in an office setting. Assessments included incontinence quality of life (I-QOL and urogenital distress inventory (UDI-6 instruments. Results. In total, 139 women were enrolled and 136 women were treated (mean age, 47 years. At 36 months, intent-to-treat analysis (n=139 revealed significant improvements in quality of life. Mean I-QOL score improved 17 points from baseline (P=.0004, while mean UDI-6 score improved (decreased 19 points (P=.0005. Conclusions. Transurethral collagen denaturation is a low-risk, office-based procedure that results in durable quality-of-life improvements in a significant proportion of women for as long as 3 years.

  8. Effects of the protein denaturant guanidinium chloride on aqueous hydrophobic contact-pair interactions.

    Science.gov (United States)

    Macdonald, Ryan D; Khajehpour, Mazdak

    2015-01-01

    Guanidinium chloride (GdmCl) is one of the most common protein denaturants. Although GdmCl is well known in the field of protein folding, the mechanism by which it denatures proteins is not well understood. In fact, there are few studies looking at its effects on hydrophobic interactions. In this work the effect of GdmCl on hydrophobic interactions has been studied by observing how the denaturant influences model systems of phenyl and alkyl hydrophobic contact pairs. Contact pair formation is monitored through the use of fluorescence spectroscopy, i.e., measuring the intrinsic phenol fluorescence being quenched by carboxylate ions. Hydrophobic interactions are isolated from other interactions through a previously developed methodology. The results show that GdmCl does not significantly affect hydrophobic interactions between small moieties such as methyl groups and phenol; while on the other hand, the interaction of larger hydrophobes such as hexyl and heptyl groups with phenol is significantly destabilized.

  9. Cerebrospinal fluid sodium rhythms

    Directory of Open Access Journals (Sweden)

    Johnson Benjamin

    2010-01-01

    Full Text Available Abstract Background Cerebrospinal fluid (CSF sodium levels have been reported to rise during episodic migraine. Since migraine frequently starts in early morning or late afternoon, we hypothesized that natural sodium chronobiology may predispose susceptible persons when extracellular CSF sodium increases. Since no mammalian brain sodium rhythms are known, we designed a study of healthy humans to test if cation rhythms exist in CSF. Methods Lumbar CSF was collected every ten minutes at 0.1 mL/min for 24 h from six healthy participants. CSF sodium and potassium concentrations were measured by ion chromatography, total protein by fluorescent spectrometry, and osmolarity by freezing point depression. We analyzed cation and protein distributions over the 24 h period and spectral and permutation tests to identify significant rhythms. We applied the False Discovery Rate method to adjust significance levels for multiple tests and Spearman correlations to compare sodium fluctuations with potassium, protein, and osmolarity. Results The distribution of sodium varied much more than potassium, and there were statistically significant rhythms at 12 and 1.65 h periods. Curve fitting to the average time course of the mean sodium of all six subjects revealed the lowest sodium levels at 03.20 h and highest at 08.00 h, a second nadir at 09.50 h and a second peak at 18.10 h. Sodium levels were not correlated with potassium or protein concentration, or with osmolarity. Conclusion These CSF rhythms are the first reports of sodium chronobiology in the human nervous system. The results are consistent with our hypothesis that rising levels of extracellular sodium may contribute to the timing of migraine onset. The physiological importance of sodium in the nervous system suggests that these rhythms may have additional repercussions on ultradian functions.

  10. Impact of organic modifier and temperature on protein denaturation in hydrophobic interaction chromatography.

    Science.gov (United States)

    Bobaly, Balázs; Beck, Alain; Veuthey, Jean-Luc; Guillarme, Davy; Fekete, Szabolcs

    2016-11-30

    The goal of this study was to better understand the chromatographic conditions in which monoclonal antibodies (mAbs) of broad hydrophobicity scale and a cysteine conjugated antibody-drug conjugate (ADCs), namely brentuximab-vedotin, could denaturate. For this purpose, some experiments were carried out in HIC conditions using various organic modifier in natures and proportions, different mobile phase temperatures and also different pHs. Indeed, improper analytical conditions in hydrophobic interaction chromatography (HIC) may create reversed-phase (RP) like harsh conditions and therefore protein denaturation. In terms of organic solvents, acetonitrile (ACN) and isopropanol (IPA) were tested with proportions ranging from 0 to 40%. It appeared that IPA was a less denaturating solvent than ACN, but should be used in a reasonable range (10-15%). Temperature should also be kept reasonable (below 40°C), to limit denaturation under HIC conditions. However, the combined increase of temperature and organic content induced denaturation of protein biopharmaceuticals in all cases. Indeed, above 30-40°C and 10-15% organic modifier in mobile phase B, heavy chain (HC) and light chain (LC) fragments dissociated. Mobile phase pH was also particularly critical and denaturation was significant even under moderately acidic conditions (pH of 5.4). Today, HIC is widely used for measuring drug-to-antibody ratio (DAR) of ADCs, which is a critical quality attribute of such samples. Here, we demonstrated that the estimation of average DAR can be dependent on the amount of organic modifier in the mobile phase under HIC conditions, due to the better recovery of the most hydrophobic proteins in presence of organic solvent (IPA). So, special care should be taken when measuring the average DAR of ADCs in HIC. Copyright © 2016 Elsevier B.V. All rights reserved.

  11. Effects of Glucides on Thermal Denaturation and Coagulation of Whey Proteins Studied by Ultraviolet Spectroscopy

    Science.gov (United States)

    Mongo Antoine, Etou; Abena, A. A.; Gbeassor, M.; Chaveron, H.

    The thermal coagulation of whey proteins concentrates was inhibited by various glucides. The disaccharides, saccharose and lactose, were most effective and the amino sugar, glucosamine, least effective in this respect. Ultraviolet absorption and light-scattering measurements on thermal denaturation and coagulation of both unfractionated and individual whey proteins (α-lactalbumin, ß-lactoglobulin and bovine serum albumin) showed that saccharose promotes the denaturation of these proteins but inhibits their subsequent coagulation. These results are interpreted in terms of the effect of saccharose on the hydrophobic interactions between solvent and protein.

  12. Surprisingly high stability of barley lipid transfer protein, LTP1, towards denaturant, heat and proteases

    DEFF Research Database (Denmark)

    Lindorff-Larsen, Kresten; Winther, J R

    2001-01-01

    Barley LTP1 belongs to a large family of plant proteins termed non-specific lipid transfer proteins. The in vivo function of these proteins is unknown, but it has been suggested that they are involved in responses towards stresses such as pathogens, drought, heat, cold and salt. Also, the proteins...... have been suggested as transporters of monomers for cutin synthesis. We have analysed the stability of LTP1 towards denaturant, heat and proteases and found it to be a highly stable protein, which apparently does not denature at temperatures up to 100 degrees C. This high stability may be important...

  13. Effect of ethanol denaturant on gasoline RVP (revised). Topical report, June 21, 1993--December 31, 1993

    Energy Technology Data Exchange (ETDEWEB)

    Wu, L.; Timpe, R.C.

    1993-12-01

    The Clean Air Act (CAA) Amendments of 1990 require further reduction in gasoline Reid vapor pressure (RVP) to reduce pollution. This research focused on characterizing the effect of ethanol denaturant and water on the RVP of the final ethanol-blended fuel. Anectdotal stories tell of up to a 0.5-psi effect of ethanol denaturant on the RVP of the finished ethanol-blended gasoline. Additionally, earlier Energy & Environmental Research Center (EERC) data indicated water could have a significant effect on the RVP. It was necessary to scientifically verify these effects using acceptable laboratory protocols.

  14. Sample Preparation and Identification of Biological, Chemical and Mid-Spectrum Agents

    Science.gov (United States)

    2005-10-01

    substrate molecule is called a hydrolase. Substrates commonly used are sodium hippurate, DNA, urea, esculin, starch , casein, lecithin and polysorbate-80...processed sample are first denatured and separated by gel electrophoresis [usually sodium dodecyl polyacrylamide gel electrophoresis (SDS-PAGE)] and

  15. Solubilities of sodium nitrate, sodium nitrite, and sodium aluminate in simulated nuclear waste

    Energy Technology Data Exchange (ETDEWEB)

    Reynolds, D.A.; Herting, D.L.

    1984-09-01

    Solubilities were determined for sodium nitrate, sodium nitrite, and sodium aluminate in synthetic nuclear waste liquor. Solubilities were determined as a function of temperature and solution composition (concentrations of sodium hydroxide, sodium nitrate, sodium nitrite, and sodium aluminate). Temperature had the greatest effect on the solubilities of sodium nitrate and sodium nitrite and a somewhat lesser effect on sodium aluminate solubility. Hydroxide had a great effect on the solubilities of all three salts. Other solution components had minor effects. 2 references, 8 figures, 11 tables.

  16. Small-angle neutron scattering study of the structure of mixed micellar solutions based on heptaethylene glycol monotetradecyl ether and cesium dodecyl sulfate

    Energy Technology Data Exchange (ETDEWEB)

    Rajewska, A., E-mail: aldonar@jinr.ru [Joint Institute for Nuclear Research (Russian Federation); Medrzycka, K.; Hallmann, E. [Gdansk University of Technology (Poland); Soloviov, D. V. [Joint Institute for Nuclear Research (Russian Federation)

    2016-01-15

    The micellization in mixed aqueous systems based on a nonionic surfactant, heptaethylene glycol monotetradecyl ether (C{sub 14}E{sub 7}), and an anionic surfactant, cesium dodecyl sulfate, has been investigated by small-angle neutron scattering. Preliminary data on the behavior of the C{sub 14}E{sub 7} aqueous solutions (with three concentrations, 0.17, 0.5, and 1%) mixed with a small amount of anionic surfactant, cesium dodecyl sulfate, are reported.

  17. Heat denaturation of soy glycinin. Structural characteristics in relation to aggregation and gel formation.

    NARCIS (Netherlands)

    Lakemond, C.M.M.

    2001-01-01

    key words: soy protein; glycinin; thermal stability; pH; ionic strength;genetic variant; solubility; gelationThe main aim of this thesis was to study structural changes of soy glycinin at different conditions (pH and ionic strength) during thermal denaturation and their effect on aggregation and gel

  18. Joule Heating and Thermal Denaturation of Proteins in Nano-ESI Theta Tips

    Science.gov (United States)

    Zhao, Feifei; Matt, Sarah M.; Bu, Jiexun; Rehrauer, Owen G.; Ben-Amotz, Dor; McLuckey, Scott A.

    2017-10-01

    Electro-osmotically induced Joule heating in theta tips and its effect on protein denaturation were investigated. Myoglobin, equine cytochrome c, bovine cytochrome c, and carbonic anhydrase II solutions were subjected to electro-osmosis in a theta tip and all of the proteins were denatured during the process. The extent of protein denaturation was found to increase with the applied square wave voltage and electrolyte concentration. The solution temperature at the end of a theta tip was measured directly by Raman spectroscopy and shown to increase with the square wave voltage, thereby demonstrating the effect of Joule heating through an independent method. The electro-osmosis of a solution comprised of myoglobin, bovine cytochrome c, and ubiquitin demonstrated that the magnitude of Joule heating that causes protein denaturation is positively correlated with protein melting temperature. This allows for a quick determination of a protein's relative thermal stability. This work establishes a fast, novel method for protein conformation manipulation prior to MS analysis and provides a temperature-controllable platform for the study of processes that take place in solution with direct coupling to mass spectrometry. [Figure not available: see fulltext.

  19. Manifestations of native topology in the denatured state ensemble of Rhodopseudomonas palustris cytochrome c'.

    Science.gov (United States)

    Dar, Tanveer A; Schaeffer, R Dustin; Daggett, Valerie; Bowler, Bruce E

    2011-02-15

    To provide insight into the role of local sequence in the nonrandom coil behavior of the denatured state, we have extended our measurements of histidine-heme loop formation equilibria for cytochrome c' to 6 M guanidine hydrochloride. We observe that there is some reduction in the scatter about the best fit line of loop stability versus loop size data in 6 M versus 3 M guanidine hydrochloride, but the scatter is not eliminated. The scaling exponent, ν(3), of 2.5 ± 0.2 is also similar to that found previously in 3 M guanidine hydrochloride (2.6 ± 0.3). Rates of histidine-heme loop breakage in the denatured state of cytochrome c' show that some histidine-heme loops are significantly more persistent than others at both 3 and 6 M guanidine hydrochloride. Rates of histidine-heme loop formation more closely approximate random coil behavior. This observation indicates that heterogeneity in the denatured state ensemble results mainly from contact persistence. When mapped onto the structure of cytochrome c', the histidine-heme loops with slow breakage rates coincide with chain reversals between helices 1 and 2 and between helices 2 and 3. Molecular dynamics simulations of the unfolding of cytochrome c' at 498 K show that these reverse turns persist in the unfolded state. Thus, these portions of the primary structure of cytochrome c' set up the topology of cytochrome c' in the denatured state, predisposing the protein to fold efficiently to its native structure.

  20. ASP53, a thermostable protein from Acacia erioloba seeds that protects target proteins against thermal denaturation

    CSIR Research Space (South Africa)

    Mtwisha, L

    2007-02-01

    Full Text Available stages of protein thermal denaturation. ASP53 decreased the rate of loss of alcohol dehydrogenase activity at 55°C, decreased the rate of temperature-dependent loss of secondary structure of haemoglobin and completely inhibited the temperature...

  1. Denaturing gradient gel electrophoresis analysis to study bacterial community structure in pockets of periodontitis patients

    NARCIS (Netherlands)

    Zijnge, V.; Harmsen, H.J.M.; Kleinfelder, J.W.; Rest, M.E. van der; Degener, J.E.; Welling, G.W.

    2003-01-01

    Bacteria are involved in the onset and progression of periodontitis. A promising molecular technique, denaturing gradient gel electrophoresis (DGGE), to study microbial population dynamics in the subgingival pocket is presented. Twenty-three samples were taken from the subgingival pockets of nine pa

  2. Investigating the fermentation of cocoa by correlating denaturing gradient gel electrophoresis profiles and near infrared spectra

    DEFF Research Database (Denmark)

    Nielsen, Dennis Sandris; Snitkjær, Pia; van der Berg, Franciscus Winfried J

    2008-01-01

    of the beans and the chemical processes inside the beans have been carried out previously. Recently it has been shown that Denaturing Gradient Gel Electrophoresis (DGGE) offers an efficient tool for monitoring the microbiological changes taking place during the fermentation of cocoa. Near Infrared (NIR...

  3. A simple remedy against artifactual double bands in denaturing gradient gel electrophoresis

    NARCIS (Netherlands)

    Janse, I.; Bok, J.M.; Zwart, G.

    2004-01-01

    Denaturant gradient gel electrophoresis (DGGE) is a widely used method for mutation analysis and for studies of microbial diversity. Particular combinations of target gene fragments and primers may give rise to erroneous DGGE profiles. We report on a very straightforward means to eliminate the

  4. Thermal denaturation of protein studied by terahertz time-domain spectroscopy

    Science.gov (United States)

    Fu, Xiuhua; Li, Xiangjun; Liu, Jianjun; Du, Yong; Hong, Zhi

    2012-12-01

    In this study, the absorption spectra of native or thermal protein were measured in 0.2-1.4THz using terahertz time-domain spectroscopy (THz-TDS) system at room temperature, their absorption spectra and the refractive spectra were obtained. Experimental results indicate that protein both has strong absorption but their characteristics were not distinct in the THz region, and the absorption decreased during thermal denatured state. In order to prove protein had been denatured, we used Differential scanning calorimeter (DSC) measured their denatured temperature, from their DSC heating traces, collagen Td=101℃, Bovine serum albumin Td=97℃. While we also combined the Fourier transform infrared spectrometer (FTIR) to investigate their secondary and tertiary structure before and after denatuation, but the results did not have the distinct changes. We turned the absorption spectra and the refractive spectra to the dielectric spectra, and used the one-stage Debye model simulated the terahertz dielectric spectra of protein before and after denaturation. This research proved that the terahertz spectrum technology is feasible in testing protein that were affected by temperature or other factors which can provide theoretical foundation in the further study about the THz spectrum of protein and peptide temperature stability.

  5. Mesoscopic modeling of DNA denaturation rates: Sequence dependence and experimental comparison

    Energy Technology Data Exchange (ETDEWEB)

    Dahlen, Oda, E-mail: oda.dahlen@ntnu.no; Erp, Titus S. van, E-mail: titus.van.erp@ntnu.no [Department of Chemistry, Norwegian University of Science and Technology (NTNU), Høgskoleringen 5, Realfagbygget D3-117 7491 Trondheim (Norway)

    2015-06-21

    Using rare event simulation techniques, we calculated DNA denaturation rate constants for a range of sequences and temperatures for the Peyrard-Bishop-Dauxois (PBD) model with two different parameter sets. We studied a larger variety of sequences compared to previous studies that only consider DNA homopolymers and DNA sequences containing an equal amount of weak AT- and strong GC-base pairs. Our results show that, contrary to previous findings, an even distribution of the strong GC-base pairs does not always result in the fastest possible denaturation. In addition, we applied an adaptation of the PBD model to study hairpin denaturation for which experimental data are available. This is the first quantitative study in which dynamical results from the mesoscopic PBD model have been compared with experiments. Our results show that present parameterized models, although giving good results regarding thermodynamic properties, overestimate denaturation rates by orders of magnitude. We believe that our dynamical approach is, therefore, an important tool for verifying DNA models and for developing next generation models that have higher predictive power than present ones.

  6. Affinity chromatography of chaperones based on denatured proteins: Analysis of cell lysates of different origin.

    Science.gov (United States)

    Marchenko, N Yu; Sikorskaya, E V; Marchenkov, V V; Kashparov, I A; Semisotnov, G V

    2016-03-01

    Molecular chaperones are involved in folding, oligomerization, transport, and degradation of numerous cellular proteins. Most of chaperones are heat-shock proteins (HSPs). A number of diseases of various organisms are accompanied by changes in the structure and functional activity of chaperones, thereby revealing their vital importance. One of the fundamental properties of chaperones is their ability to bind polypeptides lacking a rigid spatial structure. Here, we demonstrate that affinity chromatography using sorbents with covalently attached denatured proteins allows effective purification and quantitative assessment of their bound protein partners. Using pure Escherichia coli chaperone GroEL (Hsp60), the capacity of denatured pepsin or lysozyme-based affinity sorbents was evaluated as 1 mg and 1.4 mg of GroEL per 1 ml of sorbent, respectively. Cell lysates of bacteria (E. coli, Thermus thermophilus, and Yersinia pseudotuberculosis), archaea (Halorubrum lacusprofundi) as well as the lysate of rat liver mitochondria were analyzed using affinity carrier with denatured lysozyme. It was found that, apart from Hsp60, other proteins with a molecular weight of about 100, 50, 40, and 20 kDa are able to interact with denatured lysozyme.

  7. Reversible Dimerization of Acid-Denatured ACBP Controlled by Helix A4

    DEFF Research Database (Denmark)

    Fieber, Wolfgang; Kragelund, Birthe Brandt; Meldal, Morten Peter;

    2005-01-01

    of dimers and revealed a cooperative stabilization of helix A4 in this process. This emphasizes its special role in the structure formation in the denatured state of ACBP. No dimers are formed in the presence of guanidine hydrochloride, which underlines the fundamental difference between the nature...

  8. Sufficient minimal model for DNA denaturation: Integration of harmonic scalar elasticity and bond energies.

    Science.gov (United States)

    Singh, Amit Raj; Granek, Rony

    2016-10-14

    We study DNA denaturation by integrating elasticity - as described by the Gaussian network model - with bond binding energies, distinguishing between different base pairs and stacking energies. We use exact calculation, within the model, of the Helmholtz free-energy of any partial denaturation state, which implies that the entropy of all formed "bubbles" ("loops") is accounted for. Considering base pair bond removal single events, the bond designated for opening is chosen by minimizing the free-energy difference for the process, over all remaining base pair bonds. Despite of its great simplicity, for several known DNA sequences our results are in accord with available theoretical and experimental studies. Moreover, we report free-energy profiles along the denaturation pathway, which allow to detect stable or meta-stable partial denaturation states, composed of bubble, as local free-energy minima separated by barriers. Our approach allows to study very long DNA strands with commonly available computational power, as we demonstrate for a few random sequences in the range 200-800 base-pairs. For the latter, we also elucidate the self-averaging property of the system. Implications for the well known breathing dynamics of DNA are elucidated.

  9. Denaturing Effects of Urea and Guanidine Hydrochloride on Hyperthermophilic Esterase from Aeropyrum pernix K1

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The changes in the activity and the conformation of the hyperthermophilic esterase derived from aerobic thermophilic Aeropyrumpernix K1 (APE1547) were studied during denaturation by guanidine hydrochloride (GdnHCl)and urea. The denaturation course of APE1547 was followed by the steady-state and time resolved fluorescence methods. An increase in the denaturant concentration in the denatured system can significantly enhance the inactivation and unfolding of APE1547. The enzyme can be completely inactivated with a urea concentration of 2. 7 mol/L or a GdnHCl concentration of 7.5 mol/L. The fluorescence emission maximum of the enzyme protein red shifts in magnitude to a maximum value(355 nm) when the concentration of GdnHCl is 5.1 mol/L. The experimental results indicate that APE1547 has a high resistance to urea. Unfolding of APE1547 in GdnHCl(4.2-6.0 mol/L) was shown to be an irreversible process. The present results indicate that the ion pairs in this protein may be a key factor for the stability of this esterase.

  10. Sufficient minimal model for DNA denaturation: Integration of harmonic scalar elasticity and bond energies

    Science.gov (United States)

    Singh, Amit Raj; Granek, Rony

    2016-10-01

    We study DNA denaturation by integrating elasticity — as described by the Gaussian network model — with bond binding energies, distinguishing between different base pairs and stacking energies. We use exact calculation, within the model, of the Helmholtz free-energy of any partial denaturation state, which implies that the entropy of all formed "bubbles" ("loops") is accounted for. Considering base pair bond removal single events, the bond designated for opening is chosen by minimizing the free-energy difference for the process, over all remaining base pair bonds. Despite of its great simplicity, for several known DNA sequences our results are in accord with available theoretical and experimental studies. Moreover, we report free-energy profiles along the denaturation pathway, which allow to detect stable or meta-stable partial denaturation states, composed of bubble, as local free-energy minima separated by barriers. Our approach allows to study very long DNA strands with commonly available computational power, as we demonstrate for a few random sequences in the range 200-800 base-pairs. For the latter, we also elucidate the self-averaging property of the system. Implications for the well known breathing dynamics of DNA are elucidated.

  11. Lysozyme Thermal Denaturation and Self-Interaction: Four Integrated Thermodynamic Experiments for the Physical Chemistry Laboratory

    Science.gov (United States)

    Schwinefus, Jeffrey J.; Schaefle, Nathaniel J.; Muth, Gregory W.; Miessler, Gary L.; Clark, Christopher A.

    2008-01-01

    As part of an effort to infuse our physical chemistry laboratory with biologically relevant, investigative experiments, we detail four integrated thermodynamic experiments that characterize the denaturation (or unfolding) and self-interaction of hen egg white lysozyme as a function of pH and ionic strength. Students first use Protein Explorer to…

  12. Triggered isothermal PCR by denaturation bubble-mediated strand exchange amplification.

    Science.gov (United States)

    Shi, Chao; Shang, Fanjin; Zhou, Meiling; Zhang, Pansong; Wang, Yifan; Ma, Cuiping

    2016-10-04

    Here, we introduced the concept of strand exchange amplification (SEA) mediated by denaturation bubbles. Similar to traditional PCR, it only employed a DNA polymerase and a pair of common primers to realize a three-step cycle process, but the entire SEA reaction was performed at a single temperature.

  13. Comparison of the fine structure of mitochondrial DNA from Saccharomyces cerevisiae and S. carlsbergensis: electron microscopy of partially denatured molecules

    DEFF Research Database (Denmark)

    Christiansen, Gunna; Christiansen, C

    1976-01-01

    Denaturation-maps of mitochondrial DNA from Saccharomyces cerevisiae and S. carlsbergensis have been derived from electron microscopic observations of partially denatured complete circular molecules and large fragments of these circles. The mitochondrial DNA from the two species differ by 6...

  14. Reversible denaturation of Brazil nut 2S albumin (Ber e1) and implication of structural destabilization on digestion by pepsin

    NARCIS (Netherlands)

    Koppelman, S.J.; Nieuwenhuizen, W.F.; Gaspari, M.; Knippels, L.M.J.; Penninks, A.H.; Knol, E.F.; Hefle, S.L.; Jongh, H.H.J.de

    2005-01-01

    The high resistance of Brazil nut 2S albumin, previously identified as an allergen, against proteolysis by pepsin was examined in this work. Although the denaturation temperature of this protein exceeds the 110 °C at neutral pH, at low pH a fully reversible thermal denaturation was observed at ∼82 °

  15. Structural properties of cyanase. Denaturation, renaturation, and role of sulfhydryls and oligomeric structure in catalytic activity.

    Science.gov (United States)

    Little, R M; Anderson, P M

    1987-07-25

    Cyanase is an inducible enzyme in Escherichia coli that catalyzes bicarbonate-dependent decomposition of cyanate to give ammonia and bicarbonate. The enzyme is composed of 8-10 identical subunits (Mr = 17,008). The objective of this study was to clarify some of the structural properties of cyanase for the purpose of understanding the relationship between oligomeric structure and catalytic activity. Circular dichroism studies showed that cyanase has a significant amount of alpha-helix and beta-sheet structure. The one sulfhydryl group per subunit does not react with 5,5'-dithiobis-(2-nitrobenzoic acid) (DTNB) unless cyanase is denatured. Denaturation is apparently complete in 10 M urea or 6 M guanidine hydrochloride, but is significantly reduced in 10 M urea by the presence of azide (analog of cyanate) and is incomplete in 8 M urea. Denatured cyanase could be renatured and reactivated (greater than 85%) by removal of denaturants. Reactivation was greatly facilitated by the presence of certain anions, particularly bicarbonate, and by high ionic strength and protein concentration. The catalytic activity of renatured cyanase was associated only with oligomer. Cyanase that had been denatured in the presence of DTNB to give a cyanase-DTNB derivative could also be renatured at 26 degrees C to give active cyanase-DTNB oligomer. The active oligomeric form of the cyanase-DTNB derivative could be converted reversibly to inactive dimer by lowering the temperature to 4 degrees C or by reduction of the ionic strength and removal of monoanions. These results provide evidence that free sulfhydryl groups are not required for catalytic activity and that catalytic activity may be dependent upon oligomeric structure.

  16. [Some properties of complexes formed by small heat shock proteins with denatured actin].

    Science.gov (United States)

    Pivovarova, A V; Chebotareva, N A; Guseev, N B; Levitskiĭ, D I

    2008-01-01

    We applied different methods to analyze the effects of the recombinant wild-type small heat shock protein with an apparent molecular mass of 27 kD (Hsp27-wt) and its S15,78,82D mutant (Hsp27-3D), which mimics the naturally occurring phosphorylation of this protein, on the thermal denaturation and aggregation of F-actin. It has been shown that, at the weight ratio of Hsp27/actin equal to 1/4, both Hsp27-wt and Hsp27-3D do not affect the thermal unfolding of F-actin but effectively prevent the aggregation of F-actin by forming soluble complexes with denatured actin. The formation of these complexes occurs upon heating and accompanies the F-actin thermal denaturation. It is known that Hsp27-wt forms high-molecular-mass oligomers, whereas Hsp27-3D forms small dimers or tetramers. However, the complexes formed by Hsp27-wt and Hsp27-3D with denatured actin did not differ in their size, as measured by dynamic light scattering, and demonstrated the same hydrodynamic radius of 17-18 nm. On the other hand, the sedimentation coefficients of these complexes were distributed within the range 10-45 S in the case of Hsp27-3D and 18-60 S in the case of Hsp27-wt. Thus, the ability of Hsp27 to form soluble complexes with denatured actin does not significantly depend on the initial oligomeric state of Hsp27.

  17. Thermodynamic properties of a second-generation poly(phenylene-pyridyl) dendron with a dodecyl-decorated periphery

    Science.gov (United States)

    Smirnova, N. N.; Markin, A. V.; Kuchkina, N. V.; Yuzik-Klimova, E. Yu.; Shushunov, A. N.; Shifrina, Z. B.

    2016-12-01

    The heat capacity of a partially crystalline second-generation poly(phenylene-pyridyl) dendron with a dodecyl-decorated periphery is studied by high-precision adiabatic vacuum and differential scanning calorimetry in the temperature range of 6 to 530 K. The thermodynamic characteristics of the glass's transition and melting are determined from the calorimetric data and the degree of its crystallinity is estimated (α = 30%). Standard thermodynamic functions (Cp°, H°- H°(0), S°- S°(0), and G°- H°(0)) for a partially crystalline dendron in the range of T → 0 to 480 K are calculated.

  18. Decode the Sodium Label Lingo

    Science.gov (United States)

    ... For Preschooler For Gradeschooler For Teen Decode the Sodium Label Lingo Published January 24, 2013 Print Email Reading food labels can help you slash sodium. Here's how to decipher them. "Sodium free" or " ...

  19. NADP-specific isocitrate dehydrogenase of Escherichia coli. IV. Purification by chromatography on Affi-Gel Blue.

    Science.gov (United States)

    Vasquez, B; Reeves, H C

    1979-05-23

    Affinity chromatography on Affi-Gel Blue has been used to purify the NADP-specific isocitrate dehydrogenase (EC 1.1.1.42) from Escherichia coli. The protocol permits rapid purification of the enzyme in milligram quantities with a yield of 50% and is carried out almost entirely at room temperature. The preparation was judged to be homogeneous by non-denaturing electrophoresis at pH 7.5 and denaturing electrophoresis in the presence of sodium dodecyl sulfate. The subunit molecular weight of 53 000, determined by sodium dodecyl sulfate gel electrophoresis, is in reasonable agreement with the value of 46 900 estimated from the amino acid composition data.

  20. Solar-mediated thermo-electrochemical oxidation of sodium dodecyl benzene sulfonate by modulating the effective oxidation potential and pathway for green remediation of wastewater

    Science.gov (United States)

    Gu, Di; Gao, Simeng; Jiang, Tingting; Wang, Baohui

    2017-03-01

    To match the relentless pursuit of three research hot points - efficient solar utilization, green and sustainable remediation of wastewater and advanced oxidation processes, solar-mediated thermo-electrochemical oxidation of surfactant was proposed and developed for green remediation of surfactant wastewater. The solar thermal electrochemical process (STEP), fully driven with solar energy to electric energy and heat and without an input of other energy, sustainably serves as efficient thermo-electrochemical oxidation of surfactant, exemplified by SDBS, in wastewater with the synergistic production of hydrogen. The electrooxidation-resistant surfactant is thermo-electrochemically oxidized to CO2 while hydrogen gas is generated by lowing effective oxidation potential and suppressing the oxidation activation energy originated from the combination of thermochemical and electrochemical effect. A clear conclusion on the mechanism of SDBS degradation can be proposed and discussed based on the theoretical analysis of electrochemical potential by quantum chemical method and experimental analysis of the CV, TG, GC, FT-IR, UV-vis, Fluorescence spectra and TOC. The degradation data provide a pilot for the treatment of SDBS wastewater that appears to occur via desulfonation followed by aromatic-ring opening. The solar thermal utilization that can initiate the desulfonation and activation of SDBS becomes one key step in the degradation process.

  1. 十二烷基硫酸钠模板法制备纳米硒%Preparation of nano-sized selenium by sodium dodecyl sulfate template method

    Institute of Scientific and Technical Information of China (English)

    李志林; 滑鹏敏

    2009-01-01

    以十二烷基硫酸钠作为软模板,用抗坏血酸还原亚硒酸制备纳米硒,并对所制得的纳米硒进行了表征,研究了反应条件对产物形貌以及粒径的影响.结果表明,当反应体系中亚硒酸浓度为0.01 mol/L,抗坏血酸浓度为0.07 mol/L,十二烷基硫酸钠质量分数为1.0%时,常温下反应7 min后可得到均匀稳定的球形红色纳米硒颗粒,平均粒径约35nm,制得的纳米硒颗粒经超声波超声后能稳定存在两个月以上.

  2. Coated capillaries with highly charged polyelectrolytes and carbon nanotubes co-aggregated with sodium dodecyl sulphate for the analysis of sulfonylureas by capillary electrophoresis.

    Science.gov (United States)

    El-Debs, Racha; Nehmé, Reine; Claude, Bérengère; Motteau, Solène; Togola, Anne; Berho, Catherine; Morin, Philippe

    2014-11-07

    Sulfonylureas (SUs) are one of the most widely used herbicides to control weeds in crops. Herein, capillary electrophoresis (CE) was used to determine four sulfonylureas in natural waters, namely chlorsulfuron (CS), iodosulfuron methyl (IM), metsulfuron methyl (MSM) and mesosulfuron methyl (MSS). First of all, a bare silica capillary was chosen with 10mM of 1-butyl-3-methylimidazolium tetrafluoroborate (bminBF4) as electrophoretic buffer (pH 9.6) containing 2 mg L(-1) of surfactant-coated single-wall carbon nanotubes (SC-SWCNTs). A dramatic deviation in migration times was observed. Therefore, a poly(diallyldimethylammonium) chloride (PDADMAC) statically coated cationic capillary was used to improve repeatability and to alter the selectivity of the separation. The electroosmotic flow (EOF) measurement revealed that the SC-SWCNTs were strongly adsorbed at the surface of the PDADMAC coating even in the absence of the surfactant-coated nanotubes in the electrolyte buffer. Consequently, a stable strong cathodic EOF and excellent repeatabilities were obtained with relative standard deviations (RSDs) on migration times and on corrected peak areas below 0.9 and 1.5%, respectively. The separation of the SUs was conducted in only 6 min. No regeneration of the coating between analyses was necessary, and high peak efficiencies up to 173,000 theoretical plates were obtained. The bi-layer coating was subsequently used to analyze sulfonylureas in tap water, in several mineral waters as well as in underground waters spiked with SUs and directly injected into the CE capillary. Copyright © 2014 Elsevier B.V. All rights reserved.

  3. Analysis of recombinant Schistosoma mansoni antigen rSmp28 by on-line liquid chromatography-mass spectrometry combined with sodium dodecyl sulfate polyacrylamide gel electrophoresis

    NARCIS (Netherlands)

    Klarskov, K.; Roecklin, D.; Bouchon, B.; Sabatie, J.; Van Dorsselaer, A.; Bischoff, Rainer

    1994-01-01

    A recombinant Schistosoma mansoni antigen produced in Saccharomyces cerevisiae and purified by glutathione-Sepharose affinity chromatography was analyzed by tryptic peptide mapping using on-line reversed-phase high-performance liquid chromatography pneumatically assisted electrospray mass

  4. Thermodynamic properties of Sodium Dodecyl Sulfate aqueous solutions with Methanol, Ethanol, n-Propanol and iso-Propanol at different temperatures

    Directory of Open Access Journals (Sweden)

    Md. Abdul Motin

    2015-03-01

    The ΔH# values that are positive for all the studied systems indicate that positive work has to be done to overcome the energy barrier for the flow process. The variation of ΔS# is reversing the variation of the ΔH#. The excess parameters (ΔG#E, ΔH#E data have been fitted by the least square method to the four parameter Redlich–Kister equation and the values of the parameter aj have been reported. The observed increase of thermodynamic values in the aqueous SDS region are thought to be mainly due to the combined effect of hydrophobic hydration and hydrophilic effect.

  5. Efficacy and compatibility with mass spectrometry of methods for elution of proteins from sodium dodecyl sulfate-polyacrylamide gels and polyvinyldifluoride membranes

    DEFF Research Database (Denmark)

    Jørgensen, C.S.; Jagd, M.; Sørensen, B.K.;

    2004-01-01

    for recovering intact proteins from polyacrylamide gels and electroblotting membranes to define efficient methods compatible with MS. These methods complement in situ digestion protocols and allow determination of the molecular mass of whole proteins separated by SDS-PAGE. Passive elution of proteins from SDS...... acid (TFA) or combinations of 8 M urea and 1% Triton X-100, 1% Tween 20, or 40% isopropanol. The same result was obtained using nitrocellulose membranes, except that these were incompatible with organic solvent and TFA. Elution by TFA was compatible with matrix-assisted laser desorption/ionization MS...... (MALDI-MS) but was complicated by a high degree of trifluoroacetylation of the proteins. Alternatively, elution by 8 M urea + 1% Triton X-100, 1% Tween 20, or 40% isopropanol was compatible with both SELDI-MS and MALDI-MS. Eluted proteins were identified in MS experiments by intact mass determination...

  6. A comparative study of leukaemia inhibitory factor and interleukin-1alpha intracellular content in a human keratinocyte cell line after exposure to cosmetic fragrances and sodium dodecyl sulphate.

    Science.gov (United States)

    Parodi, Alessandro; Sanguineti, Roberta; Catalano, Mariafrancesca; Penco, Susanna; Pronzato, Maria Adelaide; Scanarotti, Chiara; Bassi, Anna Maria

    2010-02-01

    According to European laws animal testing in cosmetic industry will be prohibited in a few years and it will be replaced by alternative methods based on cell and tissue culture. Many ingredients of cosmetic formulations are potentially causes of skin inflammation and sensibilization. Since cytotoxicity is known, among other factors, to trigger irritation, in an alternative model for evaluation of skin irritation, it can be considered also the precocious release of inflammatory mediators, i.e. cytokines, originating mainly from keratinocytes. In this in vitro study we have analysed some parameters directly or indirectly related to irritation/inflammation, in NCTC 2544 human keratinocytes during short-time exposure to some potential irritants cosmetic fragrances, included in the European Laws 2003/15/EEC. IIC50 was extrapolated by MTT and NRU viability indexes after exposure of cell ultures to Geraniol Limonene and Benzylic Alcohol for 1, 3 and 6h. NCTC cells were then exposed to sub-toxic doses of selected compounds and interleukin-1alpha (IL-1alpha) and leukaemia inhibitory factor (LIF) expressions were analysed as early proinflammatory cytokines. To our knowledge our findings demonstrated for the first time that NCTC cells synthesize and modulate LIF after exposure to selected irritating stimuli. Moreover, our results give evidence on LIF role as in vitro precocious endpoint for the assessment of the risk in cosmetic field, because its response under irritation stimuli is very quick and comparable to IL-1alpha. 2009 Elsevier Ireland Ltd. All rights reserved.

  7. [Sodium and hypertension].

    Science.gov (United States)

    de Wardener, H E

    1996-09-01

    Over several million years the human race was programmed to eat a diet which contained about 15 mmol of sodium (1 g of sodium chloride) per day. It is only five to ten thousand years ago that we became addicted to salt. Today we eat about 150 mmol of sodium (9-12 g of salt) per day. It is now apparent that this sudden rise in sodium intake (in evolutionary terms) is the most likely cause for the rise in blood pressure with age that occurs in the majority of the world's population. Those which consume less than 60 mmol/day do not develop hypertension. The reason for the rise in sodium intake is not known but it is probable that an important stimulus was the discovery that meat could be preserved by immersion into a concentrated salt solution. This seemingly miraculous power endowed salt with such magical and medicinal qualities that it became a symbol of goodness and health. It was not until 1904 Ambard and Beaujard suggested that on the contrary dietary salt could be harmful and raise the blood pressure. At first the idea did not prosper and it continues to be opposed by a diminishing band. The accumulated evidence that sodium intake is related to the blood pressure in normal man and animals and in inherited forms of hypertension has been obtained from experimental manipulations and studies of human populations. The following observation links sodium and hypertension. An increase in sodium intakes raises the blood pressure of the normal rat, dog, rabbit, baboon, chimpanzee and man. Population studies have demonstrated a significant correlation between sodium intake and the customary rise in blood pressure with age. The development of hypertensive strains of rats has revealed that the primary genetic lesion which gives rise to hypertension resides in the kidney where it impairs the urinary excretion of sodium. There is similar but less convincing evidence in essential hypertension. The kidney in both essential hypertension and hypertensive strains of rats share a

  8. Isothermal DNA origami folding: avoiding denaturing conditions for one-pot, hybrid-component annealing

    Science.gov (United States)

    Kopielski, Andreas; Schneider, Anne; Csáki, Andrea; Fritzsche, Wolfgang

    2015-01-01

    The DNA origami technique offers great potential for nanotechnology. Using biomolecular self-assembly, defined 2D and 3D nanoscale DNA structures can be realized. DNA origami allows the positioning of proteins, fluorophores or nanoparticles with an accuracy of a few nanometers and enables thereby novel nanoscale devices. Origami assembly usually includes a thermal denaturation step at 90 °C. Additional components used for nanoscale assembly (such as proteins) are often thermosensitive, and possibly damaged by such harsh conditions. They have therefore to be attached in an extra second step to avoid defects. To enable a streamlined one-step nanoscale synthesis - a so called one-pot folding - an adaptation of the folding procedures is required. Here we present a thermal optimization of this process for a 2D DNA rectangle-shaped origami resulting in an isothermal assembly protocol below 60 °C without thermal denaturation. Moreover, a room temperature protocol is presented using the chemical additive betaine, which is biocompatible in contrast to chemical denaturing approaches reported previously.The DNA origami technique offers great potential for nanotechnology. Using biomolecular self-assembly, defined 2D and 3D nanoscale DNA structures can be realized. DNA origami allows the positioning of proteins, fluorophores or nanoparticles with an accuracy of a few nanometers and enables thereby novel nanoscale devices. Origami assembly usually includes a thermal denaturation step at 90 °C. Additional components used for nanoscale assembly (such as proteins) are often thermosensitive, and possibly damaged by such harsh conditions. They have therefore to be attached in an extra second step to avoid defects. To enable a streamlined one-step nanoscale synthesis - a so called one-pot folding - an adaptation of the folding procedures is required. Here we present a thermal optimization of this process for a 2D DNA rectangle-shaped origami resulting in an isothermal assembly

  9. Allergic contact stomatitis to dodecyl gallate? A review of the relevance of positive patch test results to gallates.

    Science.gov (United States)

    Gamboni, Sarah E; Palmer, Amanda M; Nixon, Rosemary L

    2013-08-01

    Gallic acid esters or gallates are antioxidants used as preservatives in food and cosmetics. Few cases of gallates causing allergic contact dermatitis (ACD) have been reported in the literature. We present a case report of a 42-year-old beauty therapist who presented with a swollen tongue. Patch testing was positive to dodecyl gallate, commonly reported as being present in edible oil and oily foods such as margarine. Our patient avoided foods presumed to contain gallates and at the 6-week review reported a substantial improvement in her tongue symptoms. We reviewed our database and found 16 (7%) definitely or possibly relevant reactions to dodecyl gallate, seven (15%) definitely or possibly relevant reactions to propyl gallate and six (3%) definitely or possibly relevant reactions to octyl gallate. Most reactions were attributed to margarine, moisturising cream and lipstick. These products are often mentioned in the literature as containing gallates; however, ingredient labelling and discussions with manufacturers made it difficult to establish whether they are currently present in foods. Ascertaining relevance for these reactions is not always possible.

  10. Effects of urea denatureation and pH on the ability of porcine myoglobin to undergo reduction.

    Science.gov (United States)

    Zhu, L G; Brewer, M S

    2003-04-01

    To determine the effects of globin moiety denaturation and pH on the ability of metmyoglobin (MetMb) to undergo reduction, MetMb isolated from porcine hearts was denatured in 8.5M urea. Both native and denatured MetMb solutions were serially reduced with Na(2)S(2)O(4) (0, 7.5, 15, 18.75, 22.5, 26.25, 30, 30.75, and 45 umol). Reduction was conducted at pH 5, 5.2, 5.4, 5.6, 6, 6.2, 6.4, 6.6, and 7. After reduction, absorbance was determined at 635 nm and the percent of the original MetMb which was reduced was calculated. The average percent MetMb reduced from the native and denatured forms was 35 and 25%, respectively. pH significantly influenced the percentage of MetMb reduced, especially when pH was <6. If the MetMb was denatured prior to reduction, the influence of pH on its ability to undergo reduction was slight. The percentage of denatured MetMb reduced was higher at pH 7 than at all other pHs. High pH enhanced the ability of MetMb to undergo reduction; while low pH decreases it. Low pH may have denatured the native globin moiety.

  11. Methodology for Extraction of Remaining Sodium of Used Sodium Containers

    Energy Technology Data Exchange (ETDEWEB)

    Jung, Minhwan; Kim, Jongman; Cho, Youngil; Jeong, Jiyoung [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2014-05-15

    Sodium used as a coolant in the SFR (Sodium-cooled Fast Reactor) reacts easily with most elements due to its high reactivity. If sodium at high temperature leaks outside of a system boundary and makes contact with oxygen, it starts to burn and toxic aerosols are produced. In addition, it generates flammable hydrogen gas through a reaction with water. Hydrogen gas can be explosive within the range of 4.75 vol%. Therefore, the sodium should be handled carefully in accordance with standard procedures even though there is a small amount of target sodium remainings inside the containers and drums used for experiment. After the experiment, all sodium experimental apparatuses should be dismantled carefully through a series of draining, residual sodium extraction, and cleaning if they are no longer reused. In this work, a system for the extraction of the remaining sodium of used sodium drums has been developed and an operation procedure for the system has been established. In this work, a methodology for the extraction of remaining sodium out of the used sodium container has been developed as one of the sodium facility maintenance works. The sodium extraction system for remaining sodium of the used drums was designed and tested successfully. This work will contribute to an establishment of sodium handling technology for PGSFR. (Prototype Gen-IV Sodium-cooled Fast Reactor)

  12. Sodium urine test

    Science.gov (United States)

    ... urine sodium level may be a sign of: Adrenal glands releasing too much hormone ( hyperaldosteronism ) Not enough fluid in the body (dehydration) Diarrhea and fluid loss Heart failure Kidney problems, such as chronic kidney disease or ...

  13. On the influence of the mixture of denaturants on protein structure stability: A molecular dynamics study

    Science.gov (United States)

    Shao, Qiang; Wang, Jinan; Zhu, Weiliang

    2014-09-01

    Mixtures of osmolytes and/or inorganic salts are present in the cell. Therefore, the understanding of the interplay of mixed osmolyte molecules and inorganic salts and their combined effects on protein structure is of fundamental importance. A novel test is presented to investigate the combined effects of urea and a chaotropic inorganic salt, potassium iodide (KI), on protein structure by using molecular dynamics simulation. It is found that the coexistence of KI and urea does not affect their respective distribution in solution. The solvation of KI salt in urea solution makes the electrostatic interactions of urea more favorable, promoting the hydrogen bonding between urea (and water) to protein backbone. The interactions from K+ and hydrogen bonding from urea and water to protein backbone work as the driving force for protein denaturation. The collaborative behavior of urea and KI salt thus enhances the denaturing ability of urea and KI mixed solution.

  14. Protective role of salt in catalysis and maintaining structure of halophilic proteins against denaturation

    Directory of Open Access Journals (Sweden)

    Rajeshwari eSinha

    2014-04-01

    Full Text Available Search for new enzymes of industrial relevance, bestowed with novel properties continues to be a desirable pursuit in enzyme research. Halophilism is the unusual existence of life in saline/ hypersaline habitats and haloenzymes, are the proteins from such origin, naturally endowed with unique structural features which enable them to sustain functionality under high salt. Driven by industrial requirements, halophilic enzymes have been explored for their stability and catalytic abilities under harsh operational conditions. These have been documented to withstand high temperature, pH, organic solvents, and chaotropic agents. However, this stability is modulated by salt. Understanding the basis of salt mediated protection amidst a denaturing milieu will add significantly to the existing knowledge about structure function relationships in halophilic proteins. Exploring their protein architecture may provide template for rationale design of stable enzymes. The article encompasses the current level of understanding about haloadaptations in halophiles and structural basis of their stability against classical denaturants.

  15. pH-sensitive polymer-assisted refolding of urea-denatured fibroblast growth factor

    Institute of Scientific and Technical Information of China (English)

    Zhi Feng Huang; Shan Shan Wang; Chun Yan Ni; Shu Lin Yang; Xiao Kun Li; Susanna S.J.Leong

    2009-01-01

    A pH-responsive polymer Eudragit S-100 has been found to assist in correct folding of FGF-2(fibroblast growth factor-2)denatured with 8 mol/L urea and 10 mmol/L dithiothreitol at pH 7.2.The refolding of FGF-2 was performed by directly diluting denatured FGF-2 into a refolding buffer containing Eudragit S-100.The ability of Eudragit S-100 to enhance protein refolding level was investigated using MTT method,fluorescence emission spectroscopy and reversc phase HPLC.On the other hand,the result shows the ability of Eudragit S-100 to enhance the refolding level of protein is due to the interaction between Eudragit S-100 and positively charged FGF-2.

  16. Theoretical aspects of pressure and solute denaturation of proteins: A Kirkwood-buff-theory approach

    Science.gov (United States)

    Ben-Naim, Arieh

    2012-12-01

    A new approach to the problem of pressure-denaturation (PD) and solute-denaturation (SD) of proteins is presented. The problem is formulated in terms of Le Chatelier principle, and a solution is sought in terms of the Kirkwood-Buff theory of solutions. It is found that both problems have one factor in common; the excluded volumes of the folded and the unfolded forms with respect to the solvent molecules. It is shown that solvent-induced effects operating on hydrophilic groups along the protein are probably the main reason for PD. On the other hand, the SD depends on the preferential solvation of the folded and the unfolded forms with respect to solvent and co-solvent molecules.

  17. ZnO nanoparticles assist the refolding of denatured green fluorescent protein.

    Science.gov (United States)

    Pandurangan, Muthuraman; Zamany, Ahmad Jawid; Kim, Doo Hwan

    2016-04-01

    Proteins are essential for cellular and biological processes. Proteins are synthesized and fold into the native structure to become active. The inability of a protein molecule to remain in its native conformation is called as protein misfolding, and this is due to several environmental factors. Protein misfolding and aggregation handle several human diseases. Protein misfolding is believed to be one of the causes of several disorders such as cancer, degenerative diseases, and metabolic pathologies. The zinc oxide (ZnO) nanoparticle was significantly promoted refolding of thermally denatured green fluorescent protein (GFP). In the present study, ZnO nanoparticles interaction with GFP was investigated by ultraviolet-visible spectrophotometer, fluorescence spectrophotometer, and dynamic light scattering. Results suggest that the ZnO nanoparticles significantly assist the refolding of denatured GFP. Copyright © 2015 John Wiley & Sons, Ltd.

  18. Small angle neutron scattering studies on protein denaturation induced by different methods

    Indian Academy of Sciences (India)

    S Chodankar; V K Aswal; J Kohlbrecher; R Vavrin; A G Wagh

    2008-11-01

    Small angle neutron scattering (SANS) has been used to study conformational changes in protein bovine serum albumin (BSA) as induced by varying temperature and in the presence of protein denaturating agents urea and surfactant. BSA has pro-late ellipsoidal shape and is found to be stable up to 60°C above which it denaturates and subsequently leads to aggregation. The protein solution exhibits a fractal structure at temperatures above 64°C, with fractal dimension increasing with temperature. BSA protein is found to unfold in the presence of urea at concentrations greater than 4 M and acquires a random coil Gaussian chain conformation. The conformation of the unfolded protein in the presence of surfactant has been determined directly using contrast variation SANS measurements by contrast matching surfactant molecules. The protein acquires a random coil Gaussian conformation on unfolding with its radius of gyration increasing with increase in surfactant concentration

  19. Teaching what one does not know: strangeness and denaturation in (autobiographical narrations

    Directory of Open Access Journals (Sweden)

    Jorge Luiz da Cunha

    2014-01-01

    Full Text Available The thematic focus in this text are the estrangement/denaturation processes in (autobiographical narrations. The aim of this study was to reflect on the possibility to promote estrangement/denatura - tion in (autobiographical writings made by teenagers in the space/ time of the classroom environment. The methodological proposal consisted on developing (autobiographical writings by students from sociology classes in High School. A total of 138 teenagers from a public school, attending the first school trimester in the year 2013, have participated in the study. The concepts of estrangement/de - naturation are located in the anthropology field and, the work with (autobiographical narrations is located in the socio-clinic perspec - tives and of biographization processes. The results indicate that (autobiographical narrations provide estrangements/denaturation and go towards teaching what one does not know. We can, then, conclude that this possibility, as an educational act, may generate knowledge suspension to self-inventiveness.

  20. PROTECTIVE EFFECT OF PROLACTIN INDUCED PROTEIN ON ZINC α2-GLYCOPROTEIN AGAINST VARIOUS DENATURANTS

    Directory of Open Access Journals (Sweden)

    Md. Imtaiyaz Hassan

    2012-12-01

    Full Text Available Zinc α2-glycoprotein (ZAG and Prolactin induced protein (PIP are considered as important elements for fertility and biomarker for prostate and breast carcinomas. The stabilities of ZAG alone and its naturally occurring complex with PIP were compared. A significant difference in CD signal was recorded for native ZAG and ZAG-PIP complex against pH-, GdnHCl- and temperature-induced denaturation. These finding suggests that PIP plays a protective role for ZAG against several denaturants. PIP contributes to the hydrophobic as well as electrostatic interactions on ZAG for the complex formation. Moreover, the observed changes in far-UV spectra between ZAG and ZAG-PIP complex in the presence of PEG support the hydrophobic nature of the forces governing the formation of complex. This pH dependent study provides evidence that formation of the complex is a natural event required for physiological function.

  1. Surface characterization of proteins using multi-fractal property of heat-denatured aggregates

    Science.gov (United States)

    Lahiri, Tapobrata; Mishra, Hrishikesh; Sarkar, Subrata; Misra, Krishna

    2008-01-01

    Multi-fractal property of heat-denatured protein aggregates (HDPA) is characteristic of its individual form. The visual similarity between digitally generated microscopic images of HDPA with that of surface-image of its individual X-ray structures in protein databank (PDB) displayed using Visual Molecular Dynamics (VMD) viewer is the basis of the study. We deigned experiments to view the fractal nature of proteins at different aggregate scales. Intensity based multi-fractal dimensions (ILMFD) extracted from various planes of digital microscopic images of protein aggregates were used to characterize HDPA into different classes. Moreover, the ILMFD parameters extracted from aggregates show similar classification pattern to digital images of protein surface displayed by VMD viewer using PDB entry. We discuss the use of irregular patterns of heat-denatured aggregate proteins to understand various surface properties in native proteins. PMID:18795110

  2. Acid Denaturation Inducing Self-Assembly of Curcumin-Loaded Hemoglobin Nanoparticles

    Directory of Open Access Journals (Sweden)

    Kaikai Wang

    2015-12-01

    Full Text Available Hemoglobin is a promising drug carrier but lacks extensive investigation. The chemical conjugation of hemoglobin and drugs is costly and complex, so we have developed curcumin-loaded hemoglobin nanoparticles (CCM-Hb-NPs via self-assembly for the first time. Using the acid-denaturing method, we avoid introducing denaturants and organic solvents. The nanoparticles are stable with uniform size. We have conducted a series of experiments to examine the interaction of hemoglobin and CCM, including hydrophobic characterization, SDS-PAGE. These experiments substantiate that this self-assembly process is mainly driven by hydrophobic forces. Our nanoparticles achieve much higher cell uptake efficiency and cytotoxicity than free CCM solution in vitro. The uptake inhibition experiments also demonstrate that our nanoparticles were incorporated via the classic clathrin-mediated endocytosis pathway. These results indicate that hemoglobin nanoparticles formed by self-assembly are a promising drug delivery system for cancer therapy.

  3. Comparison between conformational change and inactivation rates of aminoacylase during denaturation in urea solutions

    Institute of Scientific and Technical Information of China (English)

    王洪睿; 王希成; 张彤; 周海梦

    1995-01-01

    The kinetic method of the substrate reaction in the presence of mactivator previously described by Tsou has been applied to the determination of inactivation rates of aminoacylase during denaturation in urea solutions. The protective effect of substrate on the inactivation of aminoacylase by urea has been investigated. Simultaneously, the comparison between conformational change and inactivation rates of enzyme in the urea solutions of different concentrations has been studied. Results obtained show that the inactivation rate constants of the enzyme are larger than the rate constants of conformational changes. The present results show that the active site of metal enzyme-aminoacylase is also located in a limited and flexible region of the molecule that is more sensitive to denaturants than the enzyme as a whole.

  4. Formation of Native and Non-native Interactions in Ensembles of Denatured ACBP Molecules from Paramagnetic Relaxation Enhancement Studies

    DEFF Research Database (Denmark)

    Kristjansdottir, S.; Lindorff-Larsen, Kresten; Fieber, W.;

    2005-01-01

    in the denatured states with those in the transition state for folding we also provided new insights into the mechanism of formation of the native state of this protein. Keywords: protein folding; denatured state; NMR; molecular dynamics; structural studies Abbreviations: ACBP, acyl coenzyme A binding protein; Gu...... of the residual structure in the denatured state of ACBP under these different conditions has enabled us to infer that regions in the N and C-terminal parts of the protein sequence have a high tendency to interact in the unfolded state under physiological conditions. By comparing the structural features...

  5. Skeletal muscle sodium channelopathies.

    Science.gov (United States)

    Nicole, Sophie; Fontaine, Bertrand

    2015-10-01

    This is an update on skeletal muscle sodium channelopathies since knowledge in the field have dramatically increased in the past years. The relationship between two phenotypes and SCN4A has been confirmed with additional cases that remain extremely rare: severe neonatal episodic laryngospasm mimicking encephalopathy, which should be actively searched for since patients respond well to sodium channel blockers; congenital myasthenic syndromes, which have the particularity to be the first recessive Nav1.4 channelopathy. Deep DNA sequencing suggests the contribution of other ion channels in the clinical expressivity of sodium channelopathies, which may be one of the factors modulating the latter. The increased knowledge of channel molecular structure, the quantity of sodium channel blockers, and the availability of preclinical models would permit a most personalized choice of medication for patients suffering from these debilitating neuromuscular diseases. Advances in the understanding of the molecular structure of voltage-gated sodium channels, as well as availability of preclinical models, would lead to improved medical care of patients suffering from skeletal muscle, as well as other sodium channelopathies.

  6. Micro-CT Imaging of Denatured Chitin by Silver to Explore Honey Bee and Insect Pathologies

    Science.gov (United States)

    Butzloff, Peter R.

    2011-01-01

    Background Chitin and cuticle coatings are important to the environmental and immune defense of honey bees and insect pollinators. Pesticides or environmental effects may target the biochemistry of insect chitin and cuticle coating. Denaturing of chitin involves a combination of deacetylation, intercalation, oxidation, Schweiger-peeling, and the formation of amine hydrochloride salt. The term “denatured chitin” calls attention to structural and property changes to the internal membranes and external carapace of organisms so that some properties affecting biological activities are diminished. Methodology/Principal Findings A case study was performed on honey bees using silver staining and microscopic computer-tomographic x-ray radiography (micro-CT). Silver nitrate formed counter-ion complexes with labile ammonium cations and reacted with amine hydrochloride. Silver was concentrated in the peritrophic membrane, on the abdomen, in the glossa, at intersegmental joints (tarsi), at wing attachments, and in tracheal air sacs. Imaged mono-esters and fatty acids from cuticle coating on external surfaces were apparently reduced by an alcohol pretreatment. Conclusions/Significance The technique provides 3-dimensional and sectional images of individual honey bees consistent with the chemistries of silver reaction and complex formation with denatured chitin. Environmental exposures and influences such as gaseous nitric oxide intercalant, trace oxidants such as ozone gas, oligosachharide salt conversion, exposure to acid rain, and chemical or biochemical denaturing by pesticides may be studied using this technique. Peritrophic membranes, which protect against food abrasion, microorganisms, and permit efficient digestion, were imaged. Apparent surface damage to the corneal lenses of compound eyes by dilute acid exposure consistent with chitin amine hydrochloride formation was imaged. The technique can contribute to existing insect pathology research, and may provide an

  7. Thermal denaturation of beta-galactosidase and of two site-specific mutants.

    Science.gov (United States)

    Edwards, R A; Jacobson, A L; Huber, R E

    1990-12-11

    The thermal denaturation of wild-type beta-galactosidase and two beta-galactosidases with substitutions at the active site was studied by kinetics, differential scanning calorimetry, electrophoresis, molecular exclusion chromatography, and circular dichroism. From the results, a model is developed for thermal denaturation of beta-galactosidase which includes the reversible dissociation of ligands, reversible formation of an inactive tetramer, irreversible dissociation of the inactive tetramer to inactive monomers, and subsequent aggregation of inactive monomers to dimers and larger aggregates. Under some conditions, partial reversibility of the activity loss could be demonstrated, and several intermediates in the thermal denaturation process were trapped by quenching and observed by electrophoresis and molecular exclusion chromatography. The ligands Mg2+ and phenylethyl thio-beta-D-galactoside increase the stability of beta-galactosidase to heat denaturation by shifting the ligand binding equilibrium according to Le Chatelier's principle, thus decreasing the concentration of the ligand-free tetramer which can proceed to subsequent steps. Circular dichroism results indicated that beta-galactosidase is dominated by beta-sheet with lower amounts of alpha-helix. Large changes in secondary structure begin to occur only after activity has been lost. Single amino acid changes at the active site can have significant effects on thermal stability of beta-galactosidases. Some of the effects result from increased thermal stability of the ligand-free enzyme itself. Other effects result from changes in ligand binding, but the magnitude of the resulting changes in stability is not related to the strength of ligand binding in a simple fashion.

  8. Detection of Rifampin Resistance in Mycobacterium tuberculosis by Double Gradient-Denaturing Gradient Gel Electrophoresis

    Science.gov (United States)

    Scarpellini, Paolo; Braglia, Sergio; Carrera, Paola; Cedri, Maura; Cichero, Paola; Colombo, Alessia; Crucianelli, Rosella; Gori, Andrea; Ferrari, Maurizio; Lazzarin, Adriano

    1999-01-01

    We applied double gradient-denaturing gradient gel electrophoresis (DG-DGGE) for the rapid detection of rifampin (RMP) resistance from rpoB PCR products of Mycobacterium tuberculosis isolates and clinical samples. The results of this method were fully concordant with those of DNA sequencing and susceptibility testing analyses. DG-DGGE is a valid alternative to the other methods of detecting mutations for predicting RMP resistance. PMID:10508043

  9. A kinetic study of jack-bean urease denaturation by a new dithiocarbamate bismuth compound

    Science.gov (United States)

    Menezes, D. C.; Borges, E.; Torres, M. F.; Braga, J. P.

    2012-10-01

    A kinetic study concerning enzymatic inhibitory effect of a new bismuth dithiocarbamate complex on jack-bean urease is reported. A neural network approach is used to solve the ill-posed inverse problem arising from numerical treatment of the subject. A reaction mechanism for the urease denaturation process is proposed and the rate constants, relaxation time constants, equilibrium constants, activation Gibbs free energies for each reaction step and Gibbs free energies for the transition species are determined.

  10. Combining an Optical Resonance Biosensor with Enzyme Activity Kinetics to Understand Protein Adsorption and Denaturation

    OpenAIRE

    Wilson, Kerry A.; Finch, Craig A.; Anderson, Phillip; Vollmer, Frank; Hickman, James J.

    2014-01-01

    Understanding protein adsorption and resultant conformation changes on modified and unmodified silicon dioxide surfaces is a subject of keen interest in biosensors, microfluidic systems and for medical diagnostics. However, it has been proven difficult to investigate the kinetics of the adsorption process on these surfaces as well as understand the topic of the denaturation of proteins and its effect on enzyme activity. A highly sensitive optical whispering gallery mode (WGM) resonator was us...

  11. Multifocal peritoneal splenosis in Tc-99m-labeled heat-denatured red blood cell scintigraphy

    Energy Technology Data Exchange (ETDEWEB)

    Yoon, Min Ki; Hwang, Kyung Hoon; Choe, Won Sick [Gachon University Gil Medical Center, Incheon (Korea, Republic of)

    2006-06-15

    A 44-year-old man with a past medical history of splenectomy came to hospital because of epigastric pain abdominopelvic computed tomography(CT) showed a soft tissue mass and multifocal variable-sized nodules as well as finding suggestive of cholecystitis. Subsequently, he underwent Tc-99m-labeled heat- denatured red blood cell(RBC) scintigraphy to evaluate the mass and nodules. The scintigraphy confirmed multifocal peritoneal splenosis in the abdominopelvic cavity.

  12. Surface characterization of proteins using multi-fractal property of heat-denatured aggregates

    OpenAIRE

    Lahiri, Tapobrata; Mishra, Hrishikesh; Sarkar, Subrata; Misra, Krishna

    2008-01-01

    Multi-fractal property of heat-denatured protein aggregates (HDPA) is characteristic of its individual form. The visual similarity between digitally generated microscopic images of HDPA with that of surface-image of its individual X-ray structures in protein databank (PDB) displayed using Visual Molecular Dynamics (VMD) viewer is the basis of the study. We deigned experiments to view the fractal nature of proteins at different aggregate scales. Intensity based multi-fractal dimensions (ILMFD)...

  13. Thermal stability of chemically denatured green fluorescent protein (GFP) A preliminary study

    Energy Technology Data Exchange (ETDEWEB)

    Nagy, Attila; Malnasi-Csizmadia, Andras; Somogyi, Bela; Lorinczy, Denes

    2004-02-09

    Green fluorescent protein (GFP) is a light emitter in the bioluminescence reaction of the jellyfish Aequorea victoria. The protein consist of 238 amino acids and produces green fluorescent light ({lambda}{sub max}=508 nm), when irradiated with near ultraviolet light. The fluorescence is due to the presence of chromophore consisting of an imidazolone ring, formed by a post-translational modification of the tripeptide -Ser{sup 65}-Tyr{sup 66}-Gly{sup 67}-, which buried into {beta}-barrel. GFP is extremely compact and heat stable molecule. In this work, we present data for the effect of chemical denaturing agent on the thermal stability of GFP. When denaturing agent is applied, global thermal stability and the melting point of the molecule is decreases, that can be monitored with differential scanning calorimetry. The results indicate, that in 1-6 M range of GuHCl the melting temperature is decreasing continuously from 83 to 38 deg. C. Interesting finding, that the calculated calorimetric enthalpy decreases with GuHCl concentration up to 3 M (5.6-0.2 kJ mol{sup -1}), but at 4 M it jumps to 8.4 and at greater concentration it is falling down to 1.1 kJ mol{sup -1}. First phenomena, i.e. the decrease of melting point with increasing GuHCl concentration can be easily explained by the effect of the extended chemical denaturation, when less and less amount of heat required to diminish the remaining hydrogen bonds in {beta}-barrel. The surprising increase of calorimetric enthalpy at 4 M concentration of GuHCl could be the consequence of a dimerization or a formation of stable complex between GFP and denaturing agent as well as a precipitation at an extreme GuHCl concentration. We are planning further experiments to elucidate fluorescent consequence of these processes.

  14. Micro-CT imaging of denatured chitin by silver to explore honey bee and insect pathologies.

    Directory of Open Access Journals (Sweden)

    Peter R Butzloff

    Full Text Available BACKGROUND: Chitin and cuticle coatings are important to the environmental and immune defense of honey bees and insect pollinators. Pesticides or environmental effects may target the biochemistry of insect chitin and cuticle coating. Denaturing of chitin involves a combination of deacetylation, intercalation, oxidation, Schweiger-peeling, and the formation of amine hydrochloride salt. The term "denatured chitin" calls attention to structural and property changes to the internal membranes and external carapace of organisms so that some properties affecting biological activities are diminished. METHODOLOGY/PRINCIPAL FINDINGS: A case study was performed on honey bees using silver staining and microscopic computer-tomographic x-ray radiography (micro-CT. Silver nitrate formed counter-ion complexes with labile ammonium cations and reacted with amine hydrochloride. Silver was concentrated in the peritrophic membrane, on the abdomen, in the glossa, at intersegmental joints (tarsi, at wing attachments, and in tracheal air sacs. Imaged mono-esters and fatty acids from cuticle coating on external surfaces were apparently reduced by an alcohol pretreatment. CONCLUSIONS/SIGNIFICANCE: The technique provides 3-dimensional and sectional images of individual honey bees consistent with the chemistries of silver reaction and complex formation with denatured chitin. Environmental exposures and influences such as gaseous nitric oxide intercalant, trace oxidants such as ozone gas, oligosachharide salt conversion, exposure to acid rain, and chemical or biochemical denaturing by pesticides may be studied using this technique. Peritrophic membranes, which protect against food abrasion, microorganisms, and permit efficient digestion, were imaged. Apparent surface damage to the corneal lenses of compound eyes by dilute acid exposure consistent with chitin amine hydrochloride formation was imaged. The technique can contribute to existing insect pathology research, and may

  15. Comparison of membrane electroporation and protein denature in response to pulsed electric field with different durations.

    Science.gov (United States)

    Huang, Feiran; Fang, Zhihui; Mast, Jason; Chen, Wei

    2013-05-01

    In this paper, we compared the minimum potential differences in the electroporation of membrane lipid bilayers and the denaturation of membrane proteins in response to an intensive pulsed electric field with various pulse durations. Single skeletal muscle fibers were exposed to a pulsed external electric field. The field-induced changes in the membrane integrity (leakage current) and the Na channel currents were monitored to identify the minimum electric field needed to damage the membrane lipid bilayer and the membrane proteins, respectively. We found that in response to a relatively long pulsed electric shock (longer than the membrane intrinsic time constant), a lower membrane potential was needed to electroporate the cell membrane than for denaturing the membrane proteins, while for a short pulse a higher membrane potential was needed. In other words, phospholipid bilayers are more sensitive to the electric field than the membrane proteins for a long pulsed shock, while for a short pulse the proteins become more vulnerable. We can predict that for a short or ultrashort pulsed electric shock, the minimum membrane potential required to start to denature the protein functions in the cell plasma membrane is lower than that which starts to reduce the membrane integrity.

  16. DENATURATION OF NATIVE AND DEGLYCOSYLATED α-GALACTOSIDASES FROM Penicillium canescens BY GUANIDINE HYDROCHLORIDE

    Directory of Open Access Journals (Sweden)

    Borzova N. V.

    2015-08-01

    Full Text Available The aim of this work was the study of native and galactosidases from Penicillium canescens under denaturing conditions caused by guanidine hydrochloride. Calculation of kinetics and constants of enzymes inactivation was carried out on using experimental kinetic curves of enzyme denaturation. We observed significant differences in the kinetics of inactivation of native and deglycosylated α-galactosidases from P. canescens caused by guanidine hydrochloride. Native enzyme was stable within the selected range of guanidine hydrochloride concentrations (from 0.1 to 3.0 M, retaining no less than 50% of the initial enzyme activity for 3 days. Deglycosylated enzyme preparations were less stable and they lost their activity within 5–30 minutes, when they were treated with guanidine hydrochloride in concentrations above 1 M. Dissociation rate constant of native and deglycosylated forms of the enzyme differed by 10 to 100 folds. It was shown that subunit interactions play a major role in the process of inactivation of the enzyme, and the carbohydrate component is essential for stabilizing of subunit bonds and maintaining conformational stability of the enzyme under denaturing conditions of chemical agents.

  17. Thermal and mechanical denaturation properties of a DNA model with three sites per nucleotide

    CERN Document Server

    Florescu, Ana-Maria; 10.1063/1.3626870

    2011-01-01

    In this paper, we show that the coarse grain model for DNA, which has been proposed recently by Knotts, Rathore, Schwartz and de Pablo (J. Chem. Phys. 126, 084901 (2007)), can be adapted to describe the thermal and mechanical denaturation of long DNA sequences by adjusting slightly the base pairing contribution. The adjusted model leads to (i) critical temperatures for long homogeneous sequences that are in good agreement with both experimental ones and those obtained from statistical models, (ii) a realistic step-like denaturation behaviour for long inhomogeneous sequences, and (iii) critical forces at ambient temperature of the order of 10 pN, close to measured values. The adjusted model furthermore supports the conclusion that the thermal denaturation of long homogeneous sequences corresponds to a first-order phase transition and yields a critical exponent for the critical force equal to sigma=0.70. This model is both geometrically and energetically realistic, in the sense that the helical structure and th...

  18. Single domain antibodies are specially suited for quantitative determination of gliadins under denaturing conditions.

    Science.gov (United States)

    Doña, Vanina; Urrutia, Mariela; Bayardo, Mariela; Alzogaray, Vanina; Goldbaum, Fernando Alberto; Chirdo, Fernando G

    2010-01-27

    Food intended for celiac patients' consumption must be analyzed for the presence of toxic prolamins using high detectability tests. Though 60% ethanol is the most commonly used solvent for prolamins extraction, 2-mercaptoethanol (2-ME) and guanidinium chloride (GuHCl) can be added to increase protein recovery. However, ethanol and denaturing agents interfere with antigen recognition when conventional antibodies are used. In the present work, a new method for gliadins quantification is shown. The method is based on the selection of llama single domain antibody fragments able to operate under denaturing conditions. Six out of 28 VHH-phages obtained retained their binding capacity in 15% ethanol. Selected clones presented a long CDR3 region containing two additional cysteines that could be responsible for the higher stability. One of the clones (named VHH26) was fully operative in the presence of 15% ethanol, 0.5% 2-ME, and 0.5 M GuHCl. Capture ELISA using VHH26 was able to detect gliadins in samples shown as negatives by conventional ELISA. Therefore, this new strategy appears as an excellent platform for quantitative determination of proteins or any other immunogenic compound, in the presence of denaturing agents, when specific recognition units with high stability are required.

  19. Remarkable activation of enzymes in nonaqueous media by denaturing organic cosolvents

    Energy Technology Data Exchange (ETDEWEB)

    Almarsson, O.; Klibanov, A.M. [Massachusetts Inst. of Tech., Cambridge, MA (United States). Dept. of Chemistry

    1996-01-05

    The rates of transesterification reactions catalyzed by the protease subtilisin Carlsberg suspended in various anhydrous solvents at 30 C can be increased more than 100-fold by the addition of denaturing organic cosolvents (dimethyl sulfoxide or formamide); in water, the same cosolvents exert no enzyme activation. At 4 C, the activation effect on the lyophilized protease is even higher, reaching 1,000-fold. Marked enhancement of enzymatic activity in anhydrous solvents by formamide is also observed for two other enzymes, {alpha}-chymotrypsin and Rhizomucor miehei lipase, and is manifested in two transesterification reactions. In addition to lyophilized subtilisin, crosslinked crystals of subtilisin are also amenable to the dramatic activation by the denaturing cosolvents. In contrast, subtilisin solubilized in anhydrous media by covalent modification with poly(ethylene glycol) exhibits only modest activation. These observations are rationalized in terms of a mechanistic hypothesis based on an enhanced protein flexibility in anhydrous milieu brought about by the denaturing organic cosolvents. The latter exert their lubricating effect largely at the interfaces between enzyme molecules in a solid preparation, thus easing the flexibility constraints imposed by protein-protein contacts.

  20. Effects of high pressure freezing (HPF) on denaturation of natural actomyosin extracted from prawn (Metapenaeus ensis).

    Science.gov (United States)

    Cheng, Lina; Sun, Da-Wen; Zhu, Zhiwei; Zhang, Zhihang

    2017-08-15

    Effects of protein denaturation caused by high pressure freezing, involving Pressure-Factors (pressure, time) and Freezing-Factors (temperature, phase transition, recrystallization, ice crystal types), are complicated. In the current study, the conformation and functional changes of natural actomyosin (NAM) under pressure assisted freezing (PAF, (100,150,300,400,500MPa)P-20°C/25min), pressure shift freezing (PSF, (200MPa)P-20°C/25min), and immersion freezing ((0.1MPa)P-20°C/5min) after pressure was released to 0.1MPa, as compared to normal immersion freezing process (IF, (0.1MPa)P-20°C/30min). Results indicated that PSF ((200MPa)P-20°C/30min) could reduce the denaturation of frozen NAM and a pressure of 300MPa was the critical point to induce such a denaturation. During the periods of B→D in PSF or B→C→D in PAF, the generation and growth of ice crystals played an important role on changing the secondary and tertiary structure of the treated NAM. Copyright © 2017 Elsevier Ltd. All rights reserved.

  1. Fourier transform infrared spectroscopy provides an evidence of papain denaturation and aggregation during cold storage.

    Science.gov (United States)

    Rašković, Brankica; Popović, Milica; Ostojić, Sanja; Anđelković, Boban; Tešević, Vele; Polović, Natalija

    2015-01-01

    Papain is a cysteine protease with wide substrate specificity and many applications. Despite its widespread applications, cold stability of papain has never been studied. Here, we used differential spectroscopy to monitor thermal denaturation process. Papain was the most stabile from 45 °C to 60 °C with ΔG°321 of 13.9±0.3 kJ/mol and Tm value of 84±1 °C. After cold storage, papain lost parts of its native secondary structures elements which gave an increase of 40% of intermolecular β-sheet content (band maximum detected at frequency of 1621 cm(-1) in Fourier transform infrared (FT-IR) spectrum) indicating the presence of secondary structures necessary for aggregation. The presence of protein aggregates after cold storage was also proven by analytical size exclusion chromatography. After six freeze-thaw cycles around 75% of starting enzyme activity of papain was lost due to cold denaturation and aggregation of unfolded protein. Autoproteolysis of papain did not cause significant loss of the protein activity. Upon the cold storage, papain underwent structural rearrangements and aggregation that correspond to other cold denatured proteins, rather than autoproteolysis which could have the commercial importance for the growing polypeptide based industry.

  2. Stabilization of Human Serum Albumin against Urea Denaturation by Diazepam and Ketoprofen.

    Science.gov (United States)

    Manoharan, Pralad; Wong, Yin H; Tayyab, Saad

    2015-01-01

    Stabilizing effect of diazepam and ketoprofen, Sudlow's site II markers on human serum albumin (HSA) against urea denaturation was studied using fluorescence spectroscopy. The two-step, three-state urea transition of HSA was transformed into a single-step, two-state transition with the abolishment of the intermediate state along with a shift of the transition curve towards higher urea concentrations in the presence of diazepam or ketoprofen. Interestingly, a greater shift in the transition curve of HSA was observed in the presence of ketoprofen compared to diazepam. A comparison of the intrinsic fluorescence and three-dimensional fluorescence spectra of HSA and partially-denatured HSAs, obtained in the absence and the presence of diazepam or ketoprofen suggested significant retention of native-like conformation in the partially-denatured states of HSA in the presence of Sudlow's site II markers. Taken together, all these results suggested stabilization of HSA in the presence of diazepam or ketoprofen, being greater in the presence of ketoprofen.

  3. Evaluation of gasoline-denatured ethanol as a carbon source for denitrification.

    Science.gov (United States)

    Kazasi, Anna; Boardman, Gregory D; Bott, Charles B

    2013-06-01

    In this study concerning denitrification, the performance of three carbon sources, methanol (MeOH), ethanol (EtOH) and gasoline-denatured ethanol (dEtOH), was compared and evaluated on the basis of treatment efficiency, inhibition potential and cost. The gasoline denaturant considered here contained mostly aliphatic compounds and little of the components that typically boost the octane rating, such as benzene, toluene, ethylbenzene and xylenes. Results were obtained using three lab-scale SBRs operated at SRT of 12.0 +/- 0.9 days. After biomass was acclimated, denitrification rates with dEtOH were similar to those of EtOH (201 +/- 50 and 197 +/- 28 NO3-N/g MLVSS x d, respectively), and higher than those of MeOH (165 +/- 49 mg NO3-N/g MLVSS x d). The denaturant did not affect biomass production, nitrification or denitrification. Effluent soluble COD concentrations were always less than the analytical detection limit. Although the cost of dEtOH ($2.00/kg nitrate removed) was somewhat higher than that of methanol ($1.63/kg nitrate removed), the use of dEtOH is very promising and utilities will have to decide if it is worth paying a little extra to take advantage of its benefits.

  4. AFM visualization at a single-molecule level of denaturated states of proteins on graphite.

    Science.gov (United States)

    Barinov, Nikolay A; Prokhorov, Valery V; Dubrovin, Evgeniy V; Klinov, Dmitry V

    2016-10-01

    Different graphitic materials are either already used or believed to be advantageous in biomedical and biotechnological applications, e.g., as biomaterials or substrates for sensors. Most of these applications or associated important issues, such as biocompatibility, address the problem of adsorption of protein molecules and, in particular the conformational state of the adsorbed protein molecule on graphite. High-resolution AFM demonstrates highly oriented pyrolytic graphite (HOPG) induced denaturation of four proteins of blood plasma, such as ferritin, fibrinogen, human serum albumin (HSA) and immunoglobulin G (IgG), at a single molecule level. Protein denaturation is accompanied by the decrease of the heights of protein globules and spreading of the denatured protein fraction on the surface. In contrast, the modification of HOPG with the amphiphilic oligoglycine-hydrocarbon derivative monolayer preserves the native-like conformation and provides even more mild conditions for the protein adsorption than typically used mica. Protein unfolding on HOPG may have universal character for "soft" globular proteins. Copyright © 2016 Elsevier B.V. All rights reserved.

  5. Denaturation Kinetics of Whey Protein Isolate Solutions and Fouling Mass Distribution in a Plate Heat Exchanger

    Directory of Open Access Journals (Sweden)

    Marwa Khaldi

    2015-01-01

    Full Text Available Few investigations have attempted to connect the mechanism of dairy fouling to the chemical reaction of denaturation (unfolding and aggregation occurring in the bulk. The objective of this study is to contribute to this aspect in order to propose innovative controls to limit fouling deposit formation. Experimental investigations have been carried out to observe the relationship between the deposit mass distribution generated in plate heat exchangers (PHE by a whey protein isolate (WPI mainly composed of β-lactoglobulin (β-Lg and the ratio between the unfolding and aggregation rate constants. Experiments using a PHE were carried out at a pilot scale to identify the deposit distribution of a model fouling solution with different calcium contents. In parallel, laboratory experiments were performed to determine the unfolding/aggregation rate constants. Data analysis showed that (i β-Lg denaturation is highly dependent on the calcium content, (ii for each fouling solution, irrespective of the imposed temperature profile, the deposit mass in each channel and the ratio between the unfolding and aggregation rate constants seem to be well correlated. This study demonstrates that both the knowledge of the thermal profile and the β-Lg denaturation rate constants are required in order to predict accurately the deposit distribution along the PHE.

  6. 利用钠盐助磨剂制备超细黄铁矿粉体的界面光学特性%Interfacial and optical characteristics of pyrite ultrafine powder prepared using sodium salts as grinding additives

    Institute of Scientific and Technical Information of China (English)

    李丹; 尹周澜; 陈启元

    2012-01-01

    以超细黄铁矿粉体为研究对象,利用吸光度法研究黄铁矿在液相中添加六偏磷酸钠、油酸钠、硅酸钠、多聚磷酸钠、十二烷基硫酸钠后的分散性.研究结果表明:含有表面活性基团的油酸钠和十二烷基硫酸钠对于黄铁矿具有较好的分散效果.对这2种效果较好的添加剂的分散条件如pH、超声时间的影响进行分析,并对黄铁矿在这两种添加剂中的界面性质包括沉降曲线、表面电位和润湿性进行研究.在此基础上,用红外光谱对油酸钠和十二烷基硫酸钠作为助磨剂时制备黄铁矿超细粉体的光学性质结合扫描电镜进行研究,结果表明在研磨过程中黄铁矿粉体有部分硫被氧化成硫酸根,油酸钠与十二烷基硫酸钠助磨剂的使用有利于降低黄铁矿研磨过程中的氧化程度.%Using pyrite ultrafine powder as the object of this work, the dispersion of pyrite in different sodium salt additives such as sodium hexametaphosphate, sodium oleate, sodium silicate, sodium polyphosphate, and sodium dodecyl sulfate was analyzed with spectrometry. The results indicate that two surfactants namely sodium dodecyl sulfate and sodium oleate show better disperisibility for pyrite. The effects of some dispersion conditions such as pH and ultronication time on the disperisibility of dium dodecyl sulfate and sodium oleate were analyzed. The interfacial properties of pyrite dispersed in sodium dodecyl sulfate and sodium oleate solutions were investigated with precipitation curve, zeta potentiometry, and wettability. Based on these results, pyrite ultrafine powder was prepared using sodium dodecyl sulfate and sodium oleate as grinding additives, whose optical characteristics were studied by FTIR spectrometry in cooperation with scanning electron microscopy. The FTIR spectra indicate that although some parts of sulfur in pyrite are oxidized into sulfate during the grinding, sodium dodecyl sulfate and sodium oleate can

  7. Cardiac sodium channelopathies.

    Science.gov (United States)

    Amin, Ahmad S; Asghari-Roodsari, Alaleh; Tan, Hanno L

    2010-07-01

    Cardiac sodium channel are protein complexes that are expressed in the sarcolemma of cardiomyocytes to carry a large inward depolarizing current (INa) during phase 0 of the cardiac action potential. The importance of INa for normal cardiac electrical activity is reflected by the high incidence of arrhythmias in cardiac sodium channelopathies, i.e., arrhythmogenic diseases in patients with mutations in SCN5A, the gene responsible for the pore-forming ion-conducting alpha-subunit, or in genes that encode the ancillary beta-subunits or regulatory proteins of the cardiac sodium channel. While clinical and genetic studies have laid the foundation for our understanding of cardiac sodium channelopathies by establishing links between arrhythmogenic diseases and mutations in genes that encode various subunits of the cardiac sodium channel, biophysical studies (particularly in heterologous expression systems and transgenic mouse models) have provided insights into the mechanisms by which INa dysfunction causes disease in such channelopathies. It is now recognized that mutations that increase INa delay cardiac repolarization, prolong action potential duration, and cause long QT syndrome, while mutations that reduce INa decrease cardiac excitability, reduce electrical conduction velocity, and induce Brugada syndrome, progressive cardiac conduction disease, sick sinus syndrome, or combinations thereof. Recently, mutation-induced INa dysfunction was also linked to dilated cardiomyopathy, atrial fibrillation, and sudden infant death syndrome. This review describes the structure and function of the cardiac sodium channel and its various subunits, summarizes major cardiac sodium channelopathies and the current knowledge concerning their genetic background and underlying molecular mechanisms, and discusses recent advances in the discovery of mutation-specific therapies in the management of these channelopathies.

  8. Antibodies with specificity for native and denatured forms of ovalbumin differ in reactivity between enzyme-linked immunosorbent assays

    DEFF Research Database (Denmark)

    Holm, B. E.; Bergmann, Ann Christina; Hansen, Paul Robert

    2015-01-01

    In this study, polyclonal and monoclonal antibodies to native and denatured chicken ovalbumin (OVA) were produced to compare their dependency on continuous and three-dimensional epitopes. These antibodies were characterized with respect to reactivity to native and denatured OVA by enzyme......-linked immunosorbent assay (ELISA) employing surface-bound OVA and streptavidin-capture ELISA to determine whether effects of different coating influence antibody specificity and with respect to epitope specificity by peptide ELISA, using overlapping peptides, covering the complete OVA sequence. Polyclonal antibodies...... to native OVA reacted strongly with native and denatured OVA in both assays, but did not react with the overlapping peptides. Polyclonal antibodies to denatured OVA reacted strongly with both OVA forms and with several of the overlapping peptides. Monoclonal antibodies to native OVA reacted preferentially...

  9. Microencapsulation of dodecyl acetate by complex coacervation of whey protein with acacia gum and its release behavior

    Institute of Scientific and Technical Information of China (English)

    You Tong Yu; Li Na Liu; Xiao Li Zhu; Xiang Zheng Kong

    2012-01-01

    Complex coacervation of whey protein (WP) with acacia gum (AG) was carried out in water with the presence of dodecyl acetate (DA),a component of insect sex pheromones,in order to obtain microeapsules with DA as the core material and WP-AG coacervate as the wall materials.Through variations in wall/core ratios,concentrations of the wall materials in capsule preparations,DA encapsulation was optimized,which showed a high DA encapsulation was achieved when coacervation was conducted at pH 3.5 with wall/core mass ratio at 3 combined with concentration of wall materials at 1.0 wt%.Morphology and the structure of DA loaded microcapsules were examined by scanning electron microscope,which showed the microcapsules were of core/shell structure with DA encapsulated in the inner of the microcapsules.DA release was examined and the behavior of the release was discussed.

  10. Development of sodium technology

    Energy Technology Data Exchange (ETDEWEB)

    Hwang, Sung Tai; Nam, H. Y.; Choi, Y. D. [and others

    2000-05-01

    The objective of present study is to produce the experimental data for development and verification of computer codes for development of LMR and to develop the preliminary technologies for the future large scale verification experiments. A MHD experimental test loop has been constructed for the quantitative analysis of the effect of magnetic field on the sodium flow and experiments are carried out for three EM pumps. The previous pressure drop correlations are evaluated using the experimental data obtained from the pressure drop experiment in a 19-pin fuel assembly with wire spacer. An dimensionless variable is proposed to describe the amplitude and frequency of the fluctuation of free surface using the experimental data obtained from free surface experimental apparatus and an empirical correlation is developed using this dimensionless variable. An experimental test loop is constructed to measure the flow characteristics in IHX shell side and the local pressure drop in fuel assembly, and to test the vibration behaviour of fuel pins due to flow induced vibration. The sodium two-phase flow measuring technique using the electromagnetic flowmeter is developed and the sodium differential pressure drop measuring technique using the method of direct contact of sodium and oil is established. The work on the analysis of sodium fire characteristics and produce data for vlidation of computer code is performed. Perfect reopen time of self plugged leak path was observed to be about 130 minutes after water leak initiation. Reopen shape of a specimen appeared to be double layer of circular type, and reopen size of this specimen surface was about 2mm diameter on sodium side. In small water leakage experiments, the following correlation equation about the reopen time between sodium temperature and initial leak rate was obtained, {tau}{sub c} = {delta}{center_dot}g{sup -0.83}{center_dot}10{sup (3570/T{sub Na}-3.34)}, in 400-500 deg C of liquid sodium atmosphere. The characteristics

  11. Imaging high-intensity focused ultrasound-induced tissue denaturation by multispectral photoacoustic method: an ex vivo study.

    Science.gov (United States)

    Sun, Yao; O'Neill, Brian

    2013-03-10

    We present an ex vivo study for the first time, to the best of our knowledge, in multispectral photoacoustic imaging (PAI) of tissue denaturation induced by high-intensity focused ultrasound (HIFU) in this paper. Tissue of bovine muscle was thermally treated in a heated water bath and by HIFU, and then was imaged using a multispectral photoacoustic approach. Light at multiple optical wavelengths between 700 and 900 nm was delivered to the treated bovine muscle tissue to excite the photoacoustic signal. Apparent tissue denaturation has been observed in multispectral photoacoustic images after being treated in a water bath and by HIFU. It is interesting that the denaturation is more striking at shorter optical wavelength photoacoustic images than at longer optical wavelength photoacoustic images. Multispectral photoacoustic images of the tissue denaturation were further analyzed and the photoacoustic spectrums of the denaturized tissue were calculated in this paper. This study suggests that a multispectral PAI approach might be a promising tool to evaluate tissue denaturation induced by HIFU treatment.

  12. Denatured-state energy landscapes of a protein structural database reveal the energetic determinants of a framework model for folding.

    Science.gov (United States)

    Wang, Suwei; Gu, Jenny; Larson, Scott A; Whitten, Steven T; Hilser, Vincent J

    2008-09-19

    Position-specific denatured-state thermodynamics were determined for a database of human proteins by use of an ensemble-based model of protein structure. The results of modeling denatured protein in this manner reveal important sequence-dependent thermodynamic properties in the denatured ensembles as well as fundamental differences between the denatured and native ensembles in overall thermodynamic character. The generality and robustness of these results were validated by performing fold-recognition experiments, whereby sequences were matched with their respective folds based on amino acid propensities for the different energetic environments in the protein, as determined through cluster analysis. Correlation analysis between structure and energetic information revealed that sequence segments destined for beta-sheet in the final native fold are energetically more predisposed to a broader repertoire of states than are sequence segments destined for alpha-helix. These results suggest that within the subensemble of mostly unstructured states, the energy landscapes are dominated by states in which parts of helices adopt structure, whereas structure formation for sequences destined for beta-strand is far less probable. These results support a framework model of folding, which suggests that, in general, the denatured state has evolutionarily evolved to avoid low-energy conformations in sequences that ultimately adopt beta-strand. Instead, the denatured state evolved so that sequence segments that ultimately adopt alpha-helix and coil will have a high intrinsic structure formation capability, thus serving as potential nucleation sites.

  13. Melting of sodium clusters

    CERN Document Server

    Reyes-Nava, J A; Beltran, M R; Michaelian, K

    2002-01-01

    Thermal stability properties and the melting-like transition of Na_n, n=13-147, clusters are studied through microcanonical molecular dynamics simulations. The metallic bonding in the sodium clusters is mimicked by a many-body Gupta potential based on the second moment approximation of a tight-binding Hamiltonian. The characteristics of the solid-to-liquid transition in the sodium clusters are analyzed by calculating physical quantities like caloric curves, heat capacities, and root-mean-square bond length fluctuations using simulation times of several nanoseconds. Distinct melting mechanisms are obtained for the sodium clusters in the size range investigated. The calculated melting temperatures show an irregular variation with the cluster size, in qualitative agreement with recent experimental results. However, the calculated melting point for the Na_55 cluster is about 40 % lower than the experimental value.

  14. Too Much Sodium

    Centers for Disease Control (CDC) Podcasts

    2012-02-07

    This podcast is based on the February 2012 CDC Vital Signs report. Ninety percent of Americans age two and older eat too much sodium which can increase your risk for high blood pressure and often leads to heart disease and stroke, two leading causes of death in the US. Learn several small steps you can take to reduce the amount of sodium in your diet.  Created: 2/7/2012 by Centers for Disease Control and Prevention (CDC).   Date Released: 2/7/2012.

  15. Multiple unfolding intermediates of human placental alkaline phosphatase in equilibrium urea denaturation.

    Science.gov (United States)

    Hung, H C; Chang, G G

    2001-12-01

    Alkaline phosphatase is an enzyme with a typical alpha/beta hydrolase fold. The conformational stability of the human placental alkaline phosphatase was examined with the chemical denaturant urea. The red shifts of fluorescence spectra show a complex unfolding process involving multiple equilibrium intermediates indicating differential stability of the subdomains of the enzyme. None of these unfolding intermediates were observed in the presence of 83 mM NaCl, indicating the importance of ionic interactions in the stabilization of the unfolding intermediates. Guanidinium chloride, on the other hand, could stabilize one of the unfolding intermediates, which is not a salt effect. Some of the unfolding intermediates were also observed in circular dichroism spectroscopy, which clearly indicates steady loss of helical structure during unfolding, but very little change was observed for the beta strand content until the late stage of the unfolding process. The enzyme does not lose its phosphate-binding ability after substantial tertiary structure changes, suggesting that the substrate-binding region is more resistant to chemical denaturant than the other structural domains. Global analysis of the fluorescence spectral change demonstrated the following folding-unfolding process of the enzyme: N I(1) I(2) I(3) I(4) I(5) D. These discrete intermediates are stable at urea concentrations of 2.6, 4.1, 4.7, 5.5, 6.6, and 7.7 M, respectively. These intermediates are further characterized by acrylamide and/or potassium iodide quenching of the intrinsic fluorescence of the enzyme and by the hydrophobic probes, 1-anilinonaphthalene-8-sulfonic acid and 4,4'-dianilino-1,1'-binaphthyl-5,5'-disulfonic acid. The stepwise unfolding process was interpreted by the folding energy landscape in terms of the unique structure of the enzyme. The rigid central beta-strand domain is surrounded by the peripheral alpha-helical and coil structures, which are marginally stable toward a chemical

  16. Brownian dynamics simulations of sequence-dependent duplex denaturation in dynamically superhelical DNA

    Science.gov (United States)

    Mielke, Steven P.; Grønbech-Jensen, Niels; Krishnan, V. V.; Fink, William H.; Benham, Craig J.

    2005-09-01

    The topological state of DNA in vivo is dynamically regulated by a number of processes that involve interactions with bound proteins. In one such process, the tracking of RNA polymerase along the double helix during transcription, restriction of rotational motion of the polymerase and associated structures, generates waves of overtwist downstream and undertwist upstream from the site of transcription. The resulting superhelical stress is often sufficient to drive double-stranded DNA into a denatured state at locations such as promoters and origins of replication, where sequence-specific duplex opening is a prerequisite for biological function. In this way, transcription and other events that actively supercoil the DNA provide a mechanism for dynamically coupling genetic activity with regulatory and other cellular processes. Although computer modeling has provided insight into the equilibrium dynamics of DNA supercoiling, to date no model has appeared for simulating sequence-dependent DNA strand separation under the nonequilibrium conditions imposed by the dynamic introduction of torsional stress. Here, we introduce such a model and present results from an initial set of computer simulations in which the sequences of dynamically superhelical, 147 base pair DNA circles were systematically altered in order to probe the accuracy with which the model can predict location, extent, and time of stress-induced duplex denaturation. The results agree both with well-tested statistical mechanical calculations and with available experimental information. Additionally, we find that sites susceptible to denaturation show a propensity for localizing to supercoil apices, suggesting that base sequence determines locations of strand separation not only through the energetics of interstrand interactions, but also by influencing the geometry of supercoiling.

  17. A study of the thermal denaturation of the S-layer protein from Lactobacillus salivarius

    Science.gov (United States)

    Lighezan, Liliana; Georgieva, Ralitsa; Neagu, Adrian

    2012-09-01

    Surface layer (S-layer) proteins display an intrinsic self-assembly property, forming monomolecular crystalline arrays, identified in outermost structures of the cell envelope in many organisms, such as bacteria and archaea. Isolated S-layer proteins also possess the ability to recrystallize into regular lattices, being used in biotechnological applications, such as controlling the architecture of biomimetic surfaces. To this end, the stability of the S-layer proteins under high-temperature conditions is very important. In this study, the S-layer protein has been isolated from Lactobacillus salivarius 16 strain of human origin, and purified by cation-exchange chromatography. Using circular dichroism (CD) spectroscopy, we have investigated the thermal denaturation of the S-layer protein. The far- and near-UV CD spectra have been collected, and the temperature dependence of the CD signal in these spectral domains has been analyzed. The variable temperature results show that the secondary and tertiary structures of the S-layer protein change irreversibly due to the heating of the sample. After the cooling of the heated protein, the secondary and tertiary structures are partially recovered. The denaturation curves show that the protein unfolding depends on the sample concentration and on the heating rate. The secondary and tertiary structures of the protein suffer changes in the same temperature range. We have also detected an intermediate state in the protein denaturation pathway. Our results on the thermal behavior of the S-layer protein may be important for the use of S-layer proteins in biotechnological applications, as well as for a better understanding of the structure and function of S-layer proteins.

  18. Stabilizing effect of biochar on soil extracellular enzymes after a denaturing stress.

    Science.gov (United States)

    Elzobair, Khalid A; Stromberger, Mary E; Ippolito, James A

    2016-01-01

    Stabilizing extracellular enzymes may maintain enzymatic activity while protecting enzymes from proteolysis and denaturation. A study determined whether a fast pyrolysis hardwood biochar (CQuest™) would reduce evaporative losses, subsequently stabilizing soil extracellular enzymes and prohibiting potential enzymatic activity loss following a denaturing stress (microwaving). Soil was incubated in the presence of biochar (0%, 1%, 2%, 5%, or 10% by wt.) for 36 days and then exposed to microwave energies (0, 400, 800, 1600, or 3200 J g(-1) soil). Soil enzymes (β-glucosidase, β-d-cellobiosidase, N-acetyl-β-glucosaminidase, phosphatase, leucine aminopeptidase, β-xylosidase) were analyzed by fluorescence-based assays. Biochar amendment reduced leucine aminopeptidase and β-xylosidase potential activity after the incubation period and prior to stress exposure. The 10% biochar rate reduced soil water loss at the lowest stress level (400 J microwave energy g(-1) soil). Enzyme stabilization was demonstrated for β-xylosidase; intermediate biochar application rates prevented a complete loss of this enzyme's potential activity after soil was exposed to 400 (1% biochar treatment) or 1600 (5% biochar treatment) J microwave energy g(-1) soil. Remaining enzyme potential activities were not affected by biochar, and activities decreased with increasing stress levels. We concluded that biochar has the potential to reduce evaporative soil water losses and stabilize certain extracellular enzymes where activity is maintained after a denaturing stress; this effect was biochar rate and enzyme dependent. While biochar may reduce the potential activity of certain soil extracellular enzymes, this phenomenon was not universal as the majority of enzymes assayed in this study were unaffected by exposure to biochar.

  19. 40 CFR 180.1130 - N-(n-octyl)-2-pyrrolidone and N-(n-dodecyl)-2-pyrrolidone; exemptions from the requirement of a...

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 23 2010-07-01 2010-07-01 false N-(n-octyl)-2-pyrrolidone and N-(n... EXEMPTIONS FOR PESTICIDE CHEMICAL RESIDUES IN FOOD Exemptions From Tolerances § 180.1130 N-(n-octyl)-2-pyrrolidone and N-(n-dodecyl)-2-pyrrolidone; exemptions from the requirement of a tolerance....

  20. Cardiac sodium channelopathies

    NARCIS (Netherlands)

    Amin, A.S.; Asghari-Roodsari, A.; Tan, H.L.

    2010-01-01

    Cardiac sodium channel are protein complexes that are expressed in the sarcolemma of cardiomyocytes to carry a large inward depolarizing current (I-Na) during phase 0 of the cardiac action potential. The importance of I-Na for normal cardiac electrical activity is reflected by the high incidence of

  1. Cardiac sodium channelopathies

    NARCIS (Netherlands)

    Amin, A.S.; Asghari-Roodsari, A.; Tan, H.L.

    2010-01-01

    Cardiac sodium channel are protein complexes that are expressed in the sarcolemma of cardiomyocytes to carry a large inward depolarizing current (I-Na) during phase 0 of the cardiac action potential. The importance of I-Na for normal cardiac electrical activity is reflected by the high incidence of

  2. Screening for mutations in the uroporphyrinogen decarboxylase gene using denaturing gradient gel electrophoresis

    DEFF Research Database (Denmark)

    Christiansen, L; Ged, C; Hombrados, I

    1999-01-01

    The two porphyrias, familial porphyria cutanea tarda (fPCT) and hepatoerythropoietic porphyria (HEP), are associated with mutations in the gene encoding the enzyme uroporphyrinogen decarboxylase (UROD). Several mutations, most of which are private, have been identified in HEP and fPCT patients......, confirming the heterogeneity of the underlying genetic defects of these diseases. We have established a denaturing gradient gel electrophoresis (DGGE) assay for mutation detection in the UROD gene, enabling the simultaneous screening for known and unknown mutations. The established assay has proved able...

  3. Light and Heat Induced Denaturation of Photosystem Ⅱ Core Antenna Complex CP47

    Institute of Scientific and Technical Information of China (English)

    1999-01-01

    Light and heat induced denaturation of CP47, the core antenna complex of photosystem Ⅱ purified from spinach, were investigated using absorption and circular dichroism spectra.Light caused the destruction of chlorophyll a and excitonic interaction of chlorophyll a in CP47, while the protein secondary structure was not apparently changed.Heat induced the destruction of protein secondary structure and excitonic interaction of chlorophyll a, but the chlorophyll a molecule was not damaged.The results suggest that both the chlorophyll a molecular structure and the protein native conformation are necessary for excitonic interaction of chlorophyll a and the energy transfer function of the chlorophyll a binding protein.

  4. Optical Tweezers Analysis of Double-Stranded DNA Denaturation in the Presence of Urea

    Science.gov (United States)

    Zhu, Chunli; Li, Jing

    2016-09-01

    Urea is a kind of denaturant prone to form hydrogen bonds with the electronegative centers of the nitrogenous bases, threatening the stability of hydrogen bonds between DNA base pairs. In this paper, the stability and stiffness of DNA double helix influenced by urea are investigated at single-molecule level using optical tweezers. Experimental results show that DNA's double helix stability and stiffness both decrease with increasing urea concentration. In addition, the re-forming of ruptured hydrogen bonds between the base pairs is blocked by urea as the tension on DNA is released.

  5. Two-dimensional salt and temperature DNA denaturation analysis using a magnetoresistive sensor

    DEFF Research Database (Denmark)

    Rizzi, Giovanni; Dufva, Martin; Hansen, Mikkel Fougt

    2017-01-01

    . The results demonstrate that concentration melting provides an attractive alternative to temperature melting in on-chip DNA denaturation experiments and further show that the magnetoresistive platform is attractive due to its low cross-sensitivity to temperature and liquid composition....... temperature as well as salt concentration. The salt concentration melting curves were found to be more reliable than temperature melting curves. We performed a two-dimensional mapping of the melting profiles of a target to probes targeting its wild type (WT) and mutant type (MT) variants in the temperature...

  6. Immobilization of denatured DNA to macroporous supports: II. Steric and kinetic parameters of heterogeneous hybridization reactions.

    OpenAIRE

    Bünemann, H

    1982-01-01

    The accessibility of immobilized DNA has been shown to depend more crucially on the method of immobilization than on the type of support used for fixation. When sonicated denatured DNA is coupled via diazotization or via cyanogen bromide reaction to solid Sephadex G-25 and Cellex 410 or to macroporous Sephacryl S-500 and Sepharose C1-6B its accessibility varies from 100 to 24 percent. Generally the loss of accessibility is linked to a depression of the melting temperature of DNA helices forme...

  7. Glassy behavior of denatured DNA films studied by differential scanning calorimetry.

    Science.gov (United States)

    Valle-Orero, Jessica; Garden, Jean-Luc; Richard, Jacques; Wildes, Andrew; Peyrard, Michel

    2012-04-12

    We use differential scanning calorimetry (DSC) to study the properties of DNA films, made of oriented fibers, heated above the thermal denaturation temperature of the double helical form. The films show glassy properties that we investigate in two series of experiments, a slow cooling at different rates followed by a DSC scan upon heating and aging at a temperature below the glass transition. Introducing the fictive temperature to characterize the glass allows us to derive quantitative information on the relaxations of the DNA films, in particular to evaluate their enthalpy barrier. A comparison with similar aging studies on PVAc highlights some specificities of the DNA samples.

  8. Sodium fluxes in sweet pepper exposed to varying sodium concentrations

    NARCIS (Netherlands)

    Blom-Zandstra, M.; Vogelzang, S.A.; Veen, B.W.

    1998-01-01

    The sodium transport and distribution of sweet pepper (Capsicum annuum L.) under saline conditions were studied after transferring the plants to a sodium-free nutrient solution. Sodium stress up to 60 mM did not affect the growth of sweet pepper, as it appears able to counteract the unfavourable phy

  9. Sodium fluxes in sweet pepper exposed to varying sodium concentrations

    NARCIS (Netherlands)

    Blom-Zandstra, M.; Vogelzang, S.A.; Veen, B.W.

    1998-01-01

    The sodium transport and distribution of sweet pepper (Capsicum annuum L.) under saline conditions were studied after transferring the plants to a sodium-free nutrient solution. Sodium stress up to 60 mM did not affect the growth of sweet pepper, as it appears able to counteract the unfavourable

  10. Technology for sodium purity control

    Energy Technology Data Exchange (ETDEWEB)

    Jeong, Ji Young; Kim, B. H.; Kim, T. J. [Korea Atomic Energy Research Institute, Taejon (Korea)

    1999-10-01

    When sodium is used as heat transfer fluid, the plugging in coolant flow, the corrosion of structure material and the transfer of radioactive material caused by the impurities in sodium are worth considerable. Accordingly, these impurities must be monitored and controlled continuously by sodium purification devices in the heat transfer system which sodium is used as coolant. Sodium purification loop was constructed for the purpose of accumulating the technology for purity control of the coolant, developing and verifying further efficient instruments for sodium purification. The plugging meter and the cold trap is used as the implement for measuring and controlling the oxygen and the hydrogen, the main impurities in sodium coolant. They are capable of excellent performance as the implements which could detect and monitor the impurities to the concentration limit required for nuclear reactor. Sodium purification loop could be used variably according to the experimental purpose. 18 refs., 34 figs., 8 tabs. (Author)

  11. Effect of heating strategies on whey protein denaturation--Revisited by liquid chromatography quadrupole time-of-flight mass spectrometry.

    Science.gov (United States)

    Akkerman, M; Rauh, V M; Christensen, M; Johansen, L B; Hammershøj, M; Larsen, L B

    2016-01-01

    Previous standards in the area of effect of heat treatment processes on milk protein denaturation were based primarily on laboratory-scale analysis and determination of denaturation degrees by, for example, electrophoresis. In this study, whey protein denaturation was revisited by pilot-scale heating strategies and liquid chromatography quadrupole time-of-flight mass spectrometer (LC/MC Q-TOF) analysis. Skim milk was heat treated by the use of 3 heating strategies, namely plate heat exchanger (PHE), tubular heat exchanger (THE), and direct steam injection (DSI), under various heating temperatures (T) and holding times. The effect of heating strategy on the degree of denaturation of β-lactoglobulin and α-lactalbumin was determined using LC/MC Q-TOF of pH 4.5-soluble whey proteins. Furthermore, effect of heating strategy on the rennet-induced coagulation properties was studied by oscillatory rheometry. In addition, rennet-induced coagulation of heat-treated micellar casein concentrate subjected to PHE was studied. For skim milk, the whey protein denaturation increased significantly as T and holding time increased, regardless of heating method. High denaturation degrees were obtained for T >100°C using PHE and THE, whereas DSI resulted in significantly lower denaturation degrees, compared with PHE and THE. Rennet coagulation properties were impaired by increased T and holding time regardless of heating method, although DSI resulted in less impairment compared with PHE and THE. No significant difference was found between THE and PHE for effect on rennet coagulation time, whereas the curd firming rate was significantly larger for THE compared with PHE. Micellar casein concentrate possessed improved rennet coagulation properties compared with skim milk receiving equal heat treatment.

  12. Comparative study of denaturation of whey protein isolate (WPI) in convective air drying and isothermal heat treatment processes.

    Science.gov (United States)

    Haque, M Amdadul; Aldred, Peter; Chen, Jie; Barrow, Colin J; Adhikari, Benu

    2013-11-15

    The extent and nature of denaturation of whey protein isolate (WPI) in convective air drying environments was measured and analysed using single droplet drying. A custom-built, single droplet drying instrument was used for this purpose. Single droplets having 5±0.1μl volume (initial droplet diameter 1.5±0.1mm) containing 10% (w/v) WPI were dried at air temperatures of 45, 65 and 80°C for 600s at constant air velocity of 0.5m/s. The extent and nature of denaturation of WPI in isothermal heat treatment processes was measured at 65 and 80°C for 600s and compared with those obtained from convective air drying. The extent of denaturation of WPI in a high hydrostatic pressure environment (600MPa for 600s) was also determined. The results showed that at the end of 600s of convective drying at 65°C the denaturation of WPI was 68.3%, while it was only 10.8% during isothermal heat treatment at the same medium temperature. When the medium temperature was maintained at 80°C, the denaturation loss of WPI was 90.0% and 68.7% during isothermal heat treatment and convective drying, respectively. The bovine serum albumin (BSA) fraction of WPI was found to be more stable in the convective drying conditions than β-lactoglobulin and α-lactalbumin, especially at longer drying times. The extent of denaturation of WPI in convective air drying (65 and 80°C) and isotheral heat treatment (80°C) for 600s was found to be higher than its denaturation in a high hydrostatic pressure environment at ambient temperature (600MPa for 600s).

  13. Air leak seal for lung dissection plane with diode laser irradiation: monitoring heat-denature with auto-fluorescence

    Science.gov (United States)

    Gotoh, Maya; Arai, Tsunenori

    2008-02-01

    We studied the monitoring of heat-denature by autofluorescence spectrum from lung dissection plane during laser air leak sealing procedure. In order to seal the air leakage from lung in thoracotomy, we proposed novel laser sealing method with the combination of the diode laser (810nm wavelength) irradiation and indocyanine green staining (peak absorption wavelength: 805 nm). This sealing method is expected to preserve the postoperative ventilatory capacity and achieve minimally invasive surgery. We previously reported that this laser sealing only requires thin sealing margin (less than 300 μm in thickness) compared with that of the suturing or stapling. The most serious issue on the laser air leak sealing might be re-air-leakage due to rigid surface layer caused by excessive heat-denature, such as carbonization. We should achieve laser air leak sealing minimizing the degree of heat denature. Dissection planes of isolated porcine lung with /without the diode laser irradiation were prepared as samples. We measured the auto-fluorescence from these samples using a spectrometer. When the diode laser was irradiated with 400J/cm2, the surface of diode laser irradiated lung was fully carbonized. The ration of auto-fluorescence emission of 450nm / 500 nm, with 280 nm excitation wavelength was decreased less tha 50 % of initial value. That of 600 nm / 500 nm was increased over 700 % of initial value. The decreasing of the 450 nm auto-fluorescence intensity might be attributed to the heat-denaturing of the interstitial collagen in lung. However, increasing of the 600 nm didn't specify the origins, we suppose it might be originated from heat-denature substance, like carbonization. We could establish the useful monitoring for lung heat-denaturing with simple methodology. We think the auto-fluorescence measurement can be helpful not only for understanding the sealing mechanism, but also for controlling the degree of heat-denaturing during the procedure.

  14. Inhaled sodium metabisulphite induced bronchoconstriction: inhibition by nedocromil sodium and sodium cromoglycate.

    Science.gov (United States)

    Dixon, C M; Ind, P W

    1990-01-01

    1. The effects of nedocromil sodium and sodium cromoglycate on bronchoconstriction induced by inhaled sodium metabisulphite have been studied in eight atopic subjects, three of whom had mild asthma. 2. Nedocromil sodium (4 mg, 7.8 X 10(-6) M), sodium cromoglycate (10 mg, 24.1 X 10(-6) M) and matched placebo were administered by identical metered dose inhalers 30 min before a dose-response to sodium metabisulphite (5-100 mg ml-1) was performed. 3. Maximum fall in sGaw after placebo pre-treatment was -43.9 +/- 3.3% baseline (mean +/- s.e. mean). At the same metabisulphite concentration maximum fall in sGaw after sodium cromoglycate was -13.0 +/- 3.6% and after nedocromil sodium was +4.3 +/- 6.8%. Nedocromil sodium prevented any significant fall in sGaw even after higher concentrations of metabisulphite. 4. Both nedocromil sodium, 4 mg, and sodium cromoglycate, 10 mg, inhibited sodium metabisulphite induced bronchoconstriction but nedocromil sodium was significantly more effective. Relative in vivo potency of the two drugs is broadly in line with other in vivo and in vitro studies. PMID:2171616

  15. Detection of CpG methylations in human mismatch repair gene hMLH1 promoter by denaturing high-performance liquid chromatography (DHPLC)

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Objectives: To develop a novel method to detect CpG methylation by DHPLC. Methods: After DNA was treated with sodium bisulfite, mismatch repair gene hMLH1 promoter was amplified by polymerase chain reaction (PCR). DHPLC was used to separate the PCR products at their partially denaturing temperatures. BstUI digestion assay was also used for comparison study. Results: A 294bp band was obtained by PCR from each DNA samples of colon cancer cell line RKO and gastric cancer cell line PACM82. These two bands could be separated completely by DHPLC at 53° C (retention time 6.7 min for RKO vs. 6.2 min for PACM82). We concluded that the hMLH1 promoter in RKO cells is methylated, while PACM82 is not methylated, since methylation can protect the conversion of C to T and keep higher C/G content after bisulfite treatment, leading to the delayed time. These results consistent with those from BstUI digestion assay. Conclusion: Methylation in CpG islands of hMLH1 could be detected conveniently by DHPLC after bisulfite modification.

  16. Slicing sodium from bakery products

    NARCIS (Netherlands)

    Noort, M.

    2012-01-01

    The need for sodium reduction in our diet is clear to consumers, dieticians and food manufacturers. As sodium concentration has a strengthening effect on gluten, sodium reduction decreases dough mixing tolerance, dough resistance and induces dough stickiness. In particular, the latter may cause

  17. Slicing sodium from bakery products

    NARCIS (Netherlands)

    Noort, M.

    2012-01-01

    The need for sodium reduction in our diet is clear to consumers, dieticians and food manufacturers. As sodium concentration has a strengthening effect on gluten, sodium reduction decreases dough mixing tolerance, dough resistance and induces dough stickiness. In particular, the latter may cause prob

  18. Hanford site sodium management plan

    Energy Technology Data Exchange (ETDEWEB)

    Guttenberg, S.

    1995-09-25

    The Hanford Site Sodium Management Plan, Revision 1, provides changes to the major elements and management strategy to ensure an integrated and coordinated approach for disposition of the more than 350,000 gallons of sodium and related sodium facilities located at the DOE`s Hanford Site

  19. 27 CFR 21.128 - Sodium (metallic).

    Science.gov (United States)

    2010-04-01

    ... test. Clean a platinum wire by dipping it in concentrated hydrochloric acid and holding it over a Bunsen burner until the flame is no longer colored. Moisten the wire loop with hydrochloric acid and dip... OF THE TREASURY LIQUORS FORMULAS FOR DENATURED ALCOHOL AND RUM Specifications for Denaturants § 21...

  20. Molecular monitoring of the intestinal flora by denaturing high performance liquid chromatography.

    Science.gov (United States)

    Goldenberg, Oliver; Herrmann, Stefanie; Marjoram, Gina; Noyer-Weidner, Mario; Hong, George; Bereswill, Stefan; Göbel, Ulf B

    2007-01-01

    Gut flora analysis is hampered by the complexity of the intestinal microbiota and by inherent limitations of culture-based approaches. Therefore, culture-independent molecular methods based upon 16S rRNA gene analysis were applied successfully for the analysis of complex microbial communities. However, generally accepted and validated profiling methods such as denaturing and temperature gradient gel electrophoresis (DGGE/TGGE) are still laborious and time consuming. Thus, we adapted the separation of amplified bacterial 16S rRNA gene fragments by denaturing high performance liquid chromatography (DHPLC) using the WAVE Microbial Analysis System as a rapid and convenient means to display complex intestinal bacterial communities and to monitor changes in the gut flora. The separation of 16S rRNA gene fragments amplified from reference strains representing main gut bacterial populations and from human stool samples revealed that DHPLC analysis effectively detects bacterial groups predominant in the human gut flora. The investigation of faecal samples from hospitalized patients before, during and after antibiotic therapy showed that PCR-based DHPLC can be used to monitor gut flora changes. Results from DHPLC analysis were comparable with DGGE profiles generated from the same samples, demonstrating that the adapted DHPLC protocol is well suited for the analysis of complex microbial communities.