WorldWideScience

Sample records for affect surfactant denaturation

  1. 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 maltos...

  2. Evaluation of the Effectiveness of Surfactants and Denaturants to Elute and Denature Adsorbed Protein on Different Surface Chemistries.

    Science.gov (United States)

    Thyparambil, Aby A; Wei, Yang; Latour, Robert A

    2015-11-01

    The elution and/or denaturation of proteins from material surfaces by chemical excipients such as surfactants and denaturants is important for numerous applications including medical implant reprocessing, bioanalyses, and biodefense. The objective of this study was to develop and apply methods to quantitatively assess how surface chemistry and adsorption conditions influence the effectiveness of three commonly used surfactants (sodium dodecyl sulfate, n-octyl-β-d-glucoside, and 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonate) and two denaturants (guanidium hydrochloride and urea) to elute protein (hen egg white lysozyme and bovine pancreatic ribonuclease A) from three different surface chemistries (silica glass, poly(methyl methacrylate), and high-density polyethylene). The structure and bioactivity of residual protein on the surface following elution were characterized using circular dichroism spectropolarimetry and enzyme assays to assess the extent of protein denaturation. Our results indicate that the denaturants were generally more effective than the surfactants in removing the adsorbed proteins from each type of surface. Also, the denaturing capacity of these excipients on the residual proteins on the surfaces was distinctly different from their influence on the proteins in solution and was unique for each of the adsorption conditions. Taken altogether, these results reveal that the effectiveness of surfactants and denaturants to elute and denature adsorbed protein is significantly influenced by surface chemistry and the conditions from which the protein was adsorbed. These results provide a basis for the selection, design, and further development of chemical agents for protein elution and surface decontamination. PMID:26449787

  3. 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

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

    International Nuclear Information System (INIS)

    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, α-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-β-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 correlation of

  5. Optimization of microchip-based electrophoresis for monoclonal antibody product quality analysis revealed needs for extra surfactants during denaturation.

    Science.gov (United States)

    Cai, Hui; Song, Yuanli; Zhang, Jian; Shi, Ting; Fu, Ya; Li, Rong; Mussa, Nesredin; Li, Zheng Jian

    2016-02-20

    Microchip-based electrophoresis has gained increasing popularity in biopharmaceutical development and testing laboratories because of its automation and rapid analysis capabilities. One application of microchip-based electrophoresis is the assessment of size-based variants for product purity analysis. However, monoclonal antibodies analyzed by this technique sometimes exhibited different electrophoretic behaviors. In this study, when three IgG1 and five IgG4 were analyzed using microchip-based electrophoresis under reducing conditions, one of the IgG1s, denoted as mAb1, exhibited an atypical profile attributed to its specific heterogeneity resulting in separation of its heavy chain into two main species. During investigation of the atypical profile, several parameters that were critical to optimal resolution were evaluated, and the data pointed toward incomplete denaturation of mAb1 due to lack of sufficient surfactant in the vendor provided sample buffer (0.7% surfactant). Denaturation studies demonstrated that, although typical antibody profiles could be achieved at 0.7% surfactant for most antibodies analyzed, five out of eight antibodies were not fully denatured until the surfactant concentration reached 0.9% or higher, and mAb1 required a surfactant concentration of 1.3% for complete denaturation. Molecular modeling analysis revealed features in surface charge, hydrophobicity, and structure from mAb1 that led to its unique surfactant concentration-dependent electrophoretic behaviors observed. The optimized method was further evaluated for specificity, linearity, precision, and limit of quantitation for mAb1, and compared with that of conventional CE-SDS. PMID:26704629

  6. Can surfactants affect management of non-water repellent soils?

    Science.gov (United States)

    Surfactants affect the water relations of water repellent soils but may or may not affect those of wettable soils. We studied the effects of three surfactants, Aquatrols IrrigAid Gold®, an ethylene oxide/propylene oxide block copolymer, and an alkyl polyglycoside, along with untreated tap water as ...

  7. Gemini surfactants affect the structure, stability, and activity of ribonuclease Sa.

    Science.gov (United States)

    Amiri, Razieh; Bordbar, Abdol-Khalegh; Laurents, Douglas V

    2014-09-11

    Gemini surfactants have important advantages, e.g., low micromolar CMCs and slow millisecond monomer ↔ micelle kinetics, for membrane mimetics and for delivering nucleic acids for gene therapy or RNA silencing. However, as a prerequisite, it is important to characterize interactions occurring between Gemini surfactants and proteins. Here NMR and CD spectroscopies are employed to investigate the interactions of cationic Gemini surfactants with RNase Sa, a negatively charged ribonuclease. We find that RNase Sa binds Gemini surfactant monomers and micelles at pH values above 4 to form aggregates. Below pH 4, where the protein is positively charged, these aggregates dissolve and interactions are undetectable. Thermal denaturation experiments show that surfactant lowers RNase Sa's conformational stability, suggesting that surfactant binds the protein's denatured state preferentially. Finally, Gemini surfactants were found to bind RNA, leading to the formation of large complexes. Interestingly, Gemini surfactant binding did not prevent RNase Sa from cleaving RNA. PMID:25133582

  8. Denaturation and Oxidative Stability of Hemp Seed (Cannabis sativa L.) Protein Isolate as Affected by Heat Treatment.

    Science.gov (United States)

    Raikos, Vassilios; Duthie, Garry; Ranawana, Viren

    2015-09-01

    The present study investigated the impact of heat treatments on the denaturation and oxidative stability of hemp seed protein during simulated gastrointestinal digestion (GID). Heat-denatured hemp protein isolate (HPI) solutions were prepared by heating HPI (2 mg/ml, pH 6.8) to 40, 60, 80 and 100 °C for 10 min. Heat-induced denaturation of the protein isolates was monitored by polyacrylamide gel electrophoresis. Heating HPI at temperatures above 80 °C significantly reduced solubility and led to the formation of large protein aggregates. The isolates were then subjected to in vitro GID and the oxidative stability of the generated peptides was investigated. Heating did not significantly affect the formation of oxidation products during GID. The results suggest that heat treatments should ideally remain below 80 °C if heat stability and solubility of HPI are to be preserved. PMID:26142888

  9. Secondary structural changes in guanidinium hydrochloride denatured mammalian serum albumins and protective effect of small amounts of cationic gemini surfactant pentanediyl-α,ω-bis(cetyldimethylammonium bromide) and methyl-β-cyclodextrin: A spectroscopic study.

    Science.gov (United States)

    Gull, Nuzhat; Khan, Javed Masood; Ishtikhar, Mohd; Qadeer, Atiyatul; Khan, Rehan Ajmal; Gul, Mudasir; Khan, Rizwan Hasan

    2015-02-01

    In the present study the cationic gemini surfactant assisted refolding of guanidinium hydrochloride (GdCl) denatured mammalian serum albumins viz. sheep serum albumin (SSA), rat serum albumin (RSA) and porcine serum albumin (PSA) using a combination of cationic gemini surfactants, pentanediyl-α,ω-bis(cetyldimethylammonium bromide) (C16H33(CH3)2N(+)-(CH2)5-N(+)(CH3)2C16H33)⋅2Br(-) designated as G5 and methyl-β-cyclodextrin in the artificial chaperone assisted two step method, is attempted. The studies were carried out in an aqueous medium (pH 7.4) using dynamic light scattering (DLS), circular dichroism (CD), and fluorescence spectroscopy. A perusal of DLS data indicates that against the native hydrodynamic radius (Rh) of 4.3nm in SSA, 3.9nm in PSA and 3.5nm in RSA, the Rh of the said proteins, when refolding is attempted by simple dilution, increases to 21.7nm, 36.6nm and 37.2nm, respectively. Hydrodynamic radii very near to the native protein, i.e., 4.0nm, 4.1nm and 4.4nm for RSA, PSA and SSA respectively, is obtained on the sequential addition of G5 and methyl-β-cyclodextrin to the denatured protein. Circular dichroism studies corroborate with the DLS data. The results obtained from the multi-technique approach are ascribed to the presence of two charged head-groups and two hydrocarbon tails in the gemini surfactants resulting in a very strong electrostatic and hydrophobic interactions. Based on the present study it is suggested that the gemini surfactants may be utilized in the protein refolding studies and thus may address one of the most pressing demand of biotechnology industry for the development of efficient and inexpensive folding aides. PMID:25463190

  10. Heat-denaturation and aggregation of quinoa (Chenopodium quinoa) globulins as affected by the pH value.

    Science.gov (United States)

    Mäkinen, Outi E; Zannini, Emanuele; Koehler, Peter; Arendt, Elke K

    2016-04-01

    The influence of heating (100 °C; 0-15 min) on the relative molecular mass, protein unfolding and secondary structure of quinoa globulins was studied at pH 6.5 (low solubility), 8.5 and 10.5 (high solubility). The patterns of denaturation and aggregation varied with pH. Heating triggered the disruption of the disulfide bonds connecting the acidic and basic chains of the chenopodin subunits at pH 8.5 and 10.5, but not at pH 6.5. Large aggregates unable to enter a 4% SDS-PAGE gel were formed at pH 6.5 and 8.5, which became soluble under reducing conditions. Heating at pH 10.5 lead to a rapid dissociation of the native chenopodin and to the disruption of the subunits, but no SDS-insoluble aggregates were formed. No major changes in secondary structure occurred during a 15 min heating, but an increase in hydrophobicity indicated unfolding of the tertiary structure in all samples. PMID:26593460

  11. Kolliphor surfactants affect solubilization and bioavailability of fenofibrate. Studies of in vitro digestion and absorption in rats

    DEFF Research Database (Denmark)

    Berthelsen, Ragna; Holm, Rene; Jacobsen, Jette;

    2015-01-01

    Selection of excipients for drug formulations requires both intellectual and experimental considerations as many of the used excipients are affected by physiological factors, e.g., they may be digested by pancreatic enzymes in the gastrointestinal tract. In the present paper we have looked...... fenofibrate absorption optimum was seen at 15% (w/v) surfactant, displaying both the highest AUC0–24h and Cmax. The reduced absorption of fenofibrate from the formulation containing the highest level of surfactant (25% w/v) was thought to be caused by some degree of trapping within Kolliphor RH40 micelles. In...... vitro, Kolliphor ELP and EL were found to be more prone to digestion than Kolliphor RH40, though not affecting the in vivo results. The highest fenofibrate bioavailability was attained from formulations with high Kolliphor ELP/EL levels (25% (w/v)), indicating that these surfactants are the better...

  12. Low molecular weight silicones particularly facilitate human serum albumin denaturation.

    Science.gov (United States)

    Nayef, Lamees M; Khan, Madiha F; Brook, Michael A

    2015-04-01

    There is a market trend towards the administration of therapeutic proteins using sterilized, pre-filled glass syringes lubricated with silicone oil. It has been widely reported that initially clear solutions of proteins can become turbid during transport and storage, with unclear outcomes with respect to bioefficacy. While the basic processes of interactions of proteins with hydrophobic entities, leading to denaturation and aggregation, are increasingly well understood, the apparently random occurrence of such processes in syringes is not. To better understand the parameters that may be responsible for this change, we report the systematic examination of a series of factors that can affect the behavior of the protein human serum albumin (HSA) when in contact with silicone oil in water. Fluorescence spectroscopy showed that greater mixing times and greater concentrations of silicones (polydimethylsiloxane (PDMS)), especially lower molecular weight hydrophobic silicones like octamethyltetracyclosiloxane (D4), were associated with increased protein denaturation. The turbidity of HSA solutions, due to the formation both of silicone oil-in-water (O/W) emulsions and protein aggregates, was also facilitated by the presence of D4. A series of mixtures of silicone oils, all of which exhibited a viscosity of 1000 cSt but which were comprised of different silicone constituents, clearly showed a correlation between the presence of lower molecular silicones and enhanced solution turbidity. While the addition of a non-ionic silicone-polyether surfactant led to greater turbidity by increasing the number of stabilized oil droplets, it was not accompanied by protein denaturation. These results are consistent with HSA denaturation and subsequent aggregation as a consequence of contact particularly with low molecular weight, hydrophobic silicones that are more mobile, leading to more efficient protein/silicone contact. PMID:25800359

  13. Shear-driven redistribution of surfactant affects enzyme activity in well-mixed femtoliter droplets

    Energy Technology Data Exchange (ETDEWEB)

    Collier, Pat [ORNL

    2009-01-01

    We developed a microfluidic platform for splitting well-mixed, femtoliter-volume droplets from larger water-in-oil plugs, where the sizes of the daughter droplets were not limited by channel width. These droplets were separated from mother plugs at a microfabricated T-junction, which enabled the study of how increased confinement affected enzyme kinetics in droplets 4-10 {mu}m in diameter. Initial rates for enzyme catalysis in the mother plugs and the largest daughter drops were close to the average bulk rate, while the rates in smaller droplets decreased linearly with increasing surface to volume ratio. Rates in the smallest droplets decreased by a factor of 4 compared to the bulk rate. Traditional methods for detecting nonspecific adsorption at the water-oil interface were unable to detect evidence of enzyme adsorption, including pendant drop tensiometry, laser scanning confocal microscopy of drops containing labeled proteins in microemulsions, and epifluorescence microscopy of plugs and drops generated on-chip. We propose the slowing of enzyme reaction kinetics in the smaller droplets was the result of increased adsorption and inactivation of enzymes at the water-oil interface arising from transient interfacial shear stresses imparted on the daughter droplets as they split from the mother plugs and passed through the constricted opening of the T-junction. Such stresses are known to modulate the interfacial area and density of surfactant molecules that can passivate the interface. Bright field images of the splitting processes at the junction indicate that these stresses scaled with increasing surface to volume ratios of the droplets but were relatively insensitive to the average flow rate of plugs upstream of the junction.

  14. Physiological variables affecting surface film formation by native lamellar body-like pulmonary surfactant particles.

    Science.gov (United States)

    Hobi, Nina; Siber, Gerlinde; Bouzas, Virginia; Ravasio, Andrea; Pérez-Gil, Jesus; Haller, Thomas

    2014-07-01

    Pulmonary surfactant (PS) is a surface active complex of lipids and proteins that prevents the alveolar structures from collapsing and reduces the work of breathing by lowering the surface tension at the alveolar air-liquid interface (ALI). Surfactant is synthesized by the alveolar type II (AT II) cells, and it is stored in specialized organelles, the lamellar bodies (LBs), as tightly packed lipid bilayers. Upon secretion into the alveolar lining fluid, a large fraction of these particles retain most of their packed lamellar structure, giving rise to the term lamellar body like-particles (LBPs). Due to their stability in aqueous media, freshly secreted LBPs can be harvested from AT II cell preparations. However, when LBPs get in contact with an ALI, they quickly and spontaneously adsorb into a highly organized surface film. In the present study we investigated the adsorptive capacity of LBPs at an ALI under relevant physiological parameters that characterize the alveolar environment in homeostatic or in pathological conditions. Adsorption of LBPs at an ALI is highly sensitive to pH, temperature and albumin concentration and to a relatively lesser extent to changes in osmolarity or Ca(2+) concentrations in the physiological range. Furthermore, proteolysis of LBPs significantly decreases their adsorptive capacity confirming the important role of surfactant proteins in the formation of surface active films. PMID:24582711

  15. Microwave-enhanced folding and denaturation of globular proteins

    OpenAIRE

    Bohr, Henrik(Department of Physics, B.307, Danish Technical University, DK-2800 Lyngby, Denmark); 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...

  16. Biological short-chain fatty acids (SCFAs) production from waste-activated sludge affected by surfactant.

    Science.gov (United States)

    Jiang, Su; Chen, Yinguang; Zhou, Qi; Gu, Guowei

    2007-07-01

    Short-chain fatty acids (SCFAs), the preferred carbon sources for biological nutrient removal, are the important intermediate products in sludge anaerobic fermentation. Sodium dodecylbenzene sulfonate (SDBS) is a widespread used surfactant, which can be easily found in waste-activated sludge (WAS). In this investigation, the effect of SDBS on SCFAs production from WAS was investigated, and the potential of using fermentative SCFAs to promote enhanced biological phosphorus removal (EBPR) was tested. Results showed that the total SCFAs production increased significantly in the presence of SDBS at room temperature. At fermentation time of 6 days, the maximum SCFAs was 2599.1mg chemical oxygen demand (COD)/L in the presence of SDBS 0.02g/g, whereas it was only 339.1mg (COD)/L in the absence of SDBS. The SCFAs produced in the case of SDBS 0.02g/g and fermentation time 6 days consisted of acetic acid (27.1%), propionic acid (22.8%), iso-valeric acid (20.1%), iso-butyric acid (11.9%), n-butyric acid (10.4%) and n-valeric acid (7.7%). It was found that during sludge anaerobic fermentation, the solubilization of sludge particulate organic-carbon and hydrolysis of solubilized substrate as well as acidification of hydrolyzed products were all increased in the presence of SDBS, while the methane formation was decreased, the SCFAs production was therefore remarkably improved. Further investigation showed that the production of SCFAs enhanced by SDBS was caused mainly by biological effects, rather than by chemical effects and SDBS decomposition. With the fermentative SCFAs as the main carbon source, the EBPR maintained high phosphorus removal efficiency ( approximately 97%). PMID:17499838

  17. Factors affecting the design of slow release formulations of herbicides based on clay-surfactant systems. A methodological approach.

    Science.gov (United States)

    Galán-Jiménez, María Del Carmen; Mishael, Yael-Golda; Nir, Shlomo; Morillo, Esmeralda; Undabeytia, Tomás

    2013-01-01

    A search for clay-surfactant based formulations with high percentage of the active ingredient, which can yield slow release of active molecules is described. The active ingredients were the herbicides metribuzin (MZ), mesotrione (MS) and flurtamone (FL), whose solubilities were examined in the presence of four commercial surfactants; (i) neutral: two berols (B048, B266) and an alkylpolyglucoside (AG6202); (ii) cationic: an ethoxylated amine (ET/15). Significant percent of active ingredient (a.i.) in the clay/surfactant/herbicide formulations could be achieved only when most of the surfactant was added as micelles. MZ and FL were well solubilized by berols, whereas MS by ET/15. Sorption of surfactants on the clay mineral sepiolite occurred mostly by sorption of micelles, and the loadings exceeded the CEC. Higher loadings were determined for B266 and ET/15. The sorption of surfactants was modeled by using the Langmuir-Scatchard equation which permitted the determination of binding coefficients that could be used for further predictions of the sorbed amounts of surfactants under a wide range of clay/surfactant ratios. A possibility was tested of designing clay-surfactant based formulations of certain herbicides by assuming the same ratio between herbicides and surfactants in the formulations as for herbicides incorporated in micelles in solution. Calculations indicated that satisfactory FL formulations could not be synthesized. The experimental fractions of herbicides in the formulations were in agreement with the predicted ones for MS and MZ. The validity of this approach was confirmed in in vitro release tests that showed a slowing down of the release of a.i. from the designed formulations relative to the technical products. Soil dissipation studies with MS formulations also showed improved bioactivity of the clay-surfactant formulation relative to the commercial one. This methodological approach can be extended to other clay-surfactant systems for encapsulation and

  18. Factors affecting the design of slow release formulations of herbicides based on clay-surfactant systems. A methodological approach.

    Directory of Open Access Journals (Sweden)

    María Del Carmen Galán-Jiménez

    Full Text Available A search for clay-surfactant based formulations with high percentage of the active ingredient, which can yield slow release of active molecules is described. The active ingredients were the herbicides metribuzin (MZ, mesotrione (MS and flurtamone (FL, whose solubilities were examined in the presence of four commercial surfactants; (i neutral: two berols (B048, B266 and an alkylpolyglucoside (AG6202; (ii cationic: an ethoxylated amine (ET/15. Significant percent of active ingredient (a.i. in the clay/surfactant/herbicide formulations could be achieved only when most of the surfactant was added as micelles. MZ and FL were well solubilized by berols, whereas MS by ET/15. Sorption of surfactants on the clay mineral sepiolite occurred mostly by sorption of micelles, and the loadings exceeded the CEC. Higher loadings were determined for B266 and ET/15. The sorption of surfactants was modeled by using the Langmuir-Scatchard equation which permitted the determination of binding coefficients that could be used for further predictions of the sorbed amounts of surfactants under a wide range of clay/surfactant ratios. A possibility was tested of designing clay-surfactant based formulations of certain herbicides by assuming the same ratio between herbicides and surfactants in the formulations as for herbicides incorporated in micelles in solution. Calculations indicated that satisfactory FL formulations could not be synthesized. The experimental fractions of herbicides in the formulations were in agreement with the predicted ones for MS and MZ. The validity of this approach was confirmed in in vitro release tests that showed a slowing down of the release of a.i. from the designed formulations relative to the technical products. Soil dissipation studies with MS formulations also showed improved bioactivity of the clay-surfactant formulation relative to the commercial one. This methodological approach can be extended to other clay-surfactant systems for

  19. Pulmonary surfactant and lung transplantation

    OpenAIRE

    Erasmus, Michiel Elardus

    1997-01-01

    Pulmonary surfactant lowers the surface tension at the air-water interface inside the alveolus. This is achieved by adsorption of surfactant phospholipids at the air-water interface, a process controlled by surfactant-associated proteins, such as SP-A. In this way, surfactant prevents collapse of the alveolus at end expiration, prevents formation of alveolar edema and increases the compliance of the lung. In chapter 1a an overview is given how the normal function of surfactant can be affected...

  20. Fractal aggregation of DNA after thermal denaturation

    Energy Technology Data Exchange (ETDEWEB)

    Yan Lifeng; Iwasaki, Hiroshi E-mail: iwasaki@sanken.osaka-u.ac.jp

    2004-05-01

    DNA thermal denaturation was observed by atomic force microscopy (AFM) on the surface of newly cleaved mica. It was found that at temperatures higher than the melting point, denaturation of DNA molecules took place and globular particles with size distribution were formed, and these particles could aggregate together to form fractal structures, which followed the diffusion limited aggregation (DLA) model. At 100 deg. C, degradation of DNA took place and small particles of about 20 nm in size were formed, and they also aggregated in fractal structures with a lower dimension. Evaporating speed of water affects the fractal dimension.

  1. Acute toxicity of the cationic surfactant C12-benzalkonium in different bioassays: how test design affects bioavailability and effect concentrations.

    Science.gov (United States)

    Chen, Yi; Geurts, Marc; Sjollema, Sascha B; Kramer, Nynke I; Hermens, Joop L M; Droge, Steven T J

    2014-03-01

    Using an ion-exchange-based solid-phase microextraction (SPME) method, the freely dissolved concentrations of C12-benzalkonium were measured in different toxicity assays, including 1) immobilization of Daphnia magna in the presence or absence of dissolved humic acid; 2) mortality of Lumbriculus variegatus in the presence or absence of a suspension of Organisation for Economic Co-Operation and Development (OECD) sediment; 3) photosystem II inhibition of green algae Chlorella vulgaris; and 4) viability of in vitro rainbow trout gill cell line (RTgill-W1) in the presence or absence of serum proteins. Furthermore, the loss from chemical adsorption to the different test vessels used in these tests was also determined. The C12-benzalkonium sorption isotherms to the different sorbent phases were established as well. Our results show that the freely dissolved concentration is a better indicator of the actual exposure concentration than the nominal or total concentration in most test assays. Daphnia was the most sensitive species to C12-benzalkonium. The acute Daphnia and Lumbriculus tests both showed no enhanced toxicity from possible ingestion of sorbed C12-benzalkonium in comparison with water-only exposure, which is in accordance with the equilibrium partitioning theory. Moreover, the present study demonstrates that commonly used sorbent phases can strongly affect bioavailability and observed effect concentrations for C12-benzalkonium. Even stronger effects of decreased actual exposure concentrations resulting from sorption to test vessels, cells, and sorbent phases can be expected for more hydrophobic cationic surfactants. PMID:24273010

  2. Cold denaturation of staphylococcal nuclease.

    OpenAIRE

    Griko, Y. V.; Privalov, P L; Sturtevant, J M; Venyaminov SYu

    1988-01-01

    Denaturation of staphylococcal nuclease was studied in a temperature range from -7 to 70 degrees C by scanning microcalorimetry and spectropolarimetry. It was found that the native protein is maximally stable at about 20 degrees C and is denatured upon heating and cooling from this temperature. The heat and cold denaturation processes are approximated rather well by a two-state transition showing that the molecule is composed of a single cooperative system. The main difference between these t...

  3. Microscopic mechanism for cold denaturation

    OpenAIRE

    Dias, CL; Ala-Nissila, T.; Karttunen, MEJ Mikko; Vattulainen, I.; Grant, M.

    2008-01-01

    We elucidate the mechanism of cold denaturation through constant-pressure simulations for a model of hydrophobic molecules in an explicit solvent. We find that the temperature dependence of the hydrophobic effect induces, facilitates, and is the driving force for cold denaturation. The physical mechanism underlying this phenomenon is identified as the destabilization of hydrophobic contact in favor of solvent-separated configurations, the same mechanism seen in pressure-induced denaturation. ...

  4. Factors affecting the design of slow release formulations of herbicides based on clay-surfactant systems. A methodological approach

    OpenAIRE

    Galán Jiménez, C.; Mishael, Y. G.; Nir, Shlomo; Morillo González, Esmeralda; Undabeytia López, Tomás

    2013-01-01

    A search for clay-surfactant based formulations with high percentage of the active ingredient, which can yield slow release of active molecules is described. The active ingredients were the herbicides metribuzin (MZ), mesotrione (MS) and flurtamone (FL), whose solubilities were examined in the presence of four commercial surfactants; (i) neutral: two berols (B048, B266) and an alkylpolyglucoside (AG6202); (ii) cationic: an ethoxylated amine (ET/15). Significant percent of active i...

  5. Factors Affecting the Design of Slow Release Formulations of Herbicides Based on Clay-Surfactant Systems. A Methodological Approach

    OpenAIRE

    Galán-Jiménez, María del Carmen; Mishael, Yael-Golda; Nir, Shlomo; Morillo, Esmeralda; Undabeytia, Tomás

    2013-01-01

    A search for clay-surfactant based formulations with high percentage of the active ingredient, which can yield slow release of active molecules is described. The active ingredients were the herbicides metribuzin (MZ), mesotrione (MS) and flurtamone (FL), whose solubilities were examined in the presence of four commercial surfactants; (i) neutral: two berols (B048, B266) and an alkylpolyglucoside (AG6202); (ii) cationic: an ethoxylated amine (ET/15). Significant percent of active ingredient (a...

  6. NOS2 Is Critical to the Development of Emphysema in Sftpd Deficient Mice but Does Not Affect Surfactant Homeostasis

    OpenAIRE

    Knudsen, Lars; Atochina-Vasserman, Elena N.; GUO, CHANG-JIANG; Pamela A Scott; Haenni, Beat; Beers, Michael F.; Ochs, Matthias; Gow, Andrew J.

    2014-01-01

    Rationale Surfactant protein D (SP-D) has important immuno-modulatory properties. The absence of SP-D results in an inducible NO synthase (iNOS, coded by NOS2 gene) related chronic inflammation, development of emphysema-like pathophysiology and alterations of surfactant homeostasis. Objective In order to test the hypothesis that SP-D deficiency related abnormalities in pulmonary structure and function are a consequence of iNOS induced inflammation, we generated SP-D and iNOS double knockout m...

  7. 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

  8. Denaturing gradient gel electrophoresis

    International Nuclear Information System (INIS)

    It is worthwhile considering that only some 30 species make up the bulk of the bacterial population in human faeces at any one time based on the classical cultivation-based approach. The situation in the rumen is similar. Thus, it is practical to focus on specific groups of interest within the complex community. These may be the predominant or the most active species, specific physiological groups or readily identifiable (genetic) clusters of phylogenetically related organisms. Several 16S rDNA fingerprinting techniques can be invaluable for selecting and monitoring sequences or phylogenetic groups of interest and are described below. Over the past few decades, considerable attention was focussed on the identification of pure cultures of microbes on the basis of genetic polymorphisms of DNA encoding rRNA such as ribotyping, amplified fragment length polymorphism and randomly amplified polymorphic DNA. However, many of these methods require prior cultivation and are less suitable for use in analysis of complex mixed populations although important in describing cultivated microbial diversity in molecular terms. Much less attention was given to molecular characterization of complex communities. In particular, research into diversity and community structure over time has been revolutionized by the advent of molecular fingerprinting techniques for complex communities. Denaturing or temperature gradient gel electrophoresis (DGGE/TGGE) methods have been successfully applied to the analysis of human, pig, cattle, dog and rodent intestinal populations

  9. NOS2 is critical to the development of emphysema in Sftpd deficient mice but does not affect surfactant homeostasis.

    Directory of Open Access Journals (Sweden)

    Lars Knudsen

    Full Text Available RATIONALE: Surfactant protein D (SP-D has important immuno-modulatory properties. The absence of SP-D results in an inducible NO synthase (iNOS, coded by NOS2 gene related chronic inflammation, development of emphysema-like pathophysiology and alterations of surfactant homeostasis. OBJECTIVE: In order to test the hypothesis that SP-D deficiency related abnormalities in pulmonary structure and function are a consequence of iNOS induced inflammation, we generated SP-D and iNOS double knockout mice (DiNOS. METHODS: Structural data obtained by design-based stereology to quantify the emphysema-like phenotype and disturbances of the intracellular surfactant were correlated to invasive pulmonary function tests and inflammatory markers including activation markers of alveolar macrophages and compared to SP-D (Sftpd(-/- and iNOS single knockout mice (NOS2(-/- as well as wild type (WT littermates. MEASUREMENTS AND RESULTS: DiNOS mice had reduced inflammatory cells in BAL and BAL-derived alveolar macrophages showed an increased expression of markers of an alternative activation as well as reduced inflammation. As evidenced by increased alveolar numbers and surface area, emphysematous changes were attenuated in DiNOS while disturbances of the surfactant system remained virtually unchanged. Sftpd(-/- demonstrated alterations of intrinsic mechanical properties of lung parenchyma as shown by reduced stiffness and resistance at its static limits, which could be corrected by additional ablation of NOS2 gene in DiNOS. CONCLUSION: iNOS related inflammation in the absence of SP-D is involved in the emphysematous remodeling leading to a loss of alveoli and associated alterations of elastic properties of lung parenchyma while disturbances of surfactant homeostasis are mediated by different mechanisms.

  10. Supercoil formation in DNA denaturation

    OpenAIRE

    Kabakcioglu, A.; Orlandini, E.; Mukamel, D.

    2008-01-01

    We generalize the Poland-Scheraga (PS) model to the case of a circular DNA, taking into account the twisting of the two strains around each other. Guided by recent single-molecule experiments on DNA strands, we assume that the torsional stress induced by denaturation enforces formation of supercoils whose writhe absorbs the linking number expelled by the loops. Our model predicts that, when the entropy parameter of a loop satisfies $c \\le 2$, denaturation transition does not take place. On th...

  11. Cold denaturation of encapsulated ubiquitin

    OpenAIRE

    Pometun, Maxim S.; Peterson, Ronald W.; Babu, Charles R.; Wand, A. Joshua

    2006-01-01

    Theoretical considerations suggest that protein cold denaturation can potentially provide a means to explore the cooperative substructure of proteins. Protein cold denaturation is generally predicted to occur well-below the freezing point of water. Here NMR spectroscopy of ubiquitin encapsulated in reverse micelles dissolved in low viscosity alkanes is used to follow cold-induced unfolding to temperatures below −25 °C. Comparison of cold-induced structural transitions in a variety of reverse ...

  12. 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.

  13. 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.

  14. X-ray photoelectron spectroscopy and positron annihilation spectroscopy analysis of surfactant affected FePt spintronic films

    Energy Technology Data Exchange (ETDEWEB)

    Feng, Chun, E-mail: fengchun@ustb.edu.cn [Department of Materials Physics and Chemistry, University of Science and Technology Beijing, Beijing 100083 (China); Li, Xujing; Liu, Fen; Wang, Qiang [Department of Materials Physics and Chemistry, University of Science and Technology Beijing, Beijing 100083 (China); Yang, Meiyin [Department of Materials Physics and Chemistry, University of Science and Technology Beijing, Beijing 100083 (China); The Center for Micromagnetics and Information Technologies (MINT) and Department of Electrical and Computer Engineering, University of Minnesota, 200 Union St SE, Minneapolis, MN 55455 (United States); Zhao, Chongjun [Department of Materials Physics and Chemistry, University of Science and Technology Beijing, Beijing 100083 (China); Gong, Kui [Centre for the Physics of Materials and Department of Physics, McGill University, Montreal, Quebec, H3A2T8 Canada (Canada); Zhang, Peng; Wang, Bao-Yi; Cao, Xing-Zhong [Key Laboratory of Nuclear Analysis Techniques, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049 (China); Yu, Guanghua [Department of Materials Physics and Chemistry, University of Science and Technology Beijing, Beijing 100083 (China)

    2014-07-01

    This paper reports the effects of surfactant Bi atomic diffusion on the microstructure evolution and resulted property manipulation in FePt spintronic films by the quantitative studies of X-ray photoelectron spectroscopy and positron annihilation spectroscopy. The defect density in the FePt layer, which was tunable by varying the thermal treatment temperatures, was found to be remarkably enhanced correlated with the Bi atomic diffusion behavior. The observed defect density evolution substantially favors Fe(Pt) atomic migrations and lowers the energy barrier for atomic ordering transition, resulting in a great improvement of hard magnet property of the films.

  15. X-ray photoelectron spectroscopy and positron annihilation spectroscopy analysis of surfactant affected FePt spintronic films

    International Nuclear Information System (INIS)

    This paper reports the effects of surfactant Bi atomic diffusion on the microstructure evolution and resulted property manipulation in FePt spintronic films by the quantitative studies of X-ray photoelectron spectroscopy and positron annihilation spectroscopy. The defect density in the FePt layer, which was tunable by varying the thermal treatment temperatures, was found to be remarkably enhanced correlated with the Bi atomic diffusion behavior. The observed defect density evolution substantially favors Fe(Pt) atomic migrations and lowers the energy barrier for atomic ordering transition, resulting in a great improvement of hard magnet property of the films.

  16. Effect of sodium dodecyl sulfate on folding and thermal stability of acid-denatured cytochrome c: A spectroscopic approach

    OpenAIRE

    Xu, Qi; Keiderling, Timothy A

    2004-01-01

    The molten globule (MG) state can be an intermediate in the protein folding pathway; thus, its detailed description can help understanding protein folding. Sodium dodecyl sulfate (SDS), an anionic surfactant that is commonly used to mimic hydrophobic binding environments such as cell membranes, is known to denature some native state proteins, including horse cytochrome c (cyt c). In this article, refolding of acid denatured cyt c is studied under the influence of SDS to form MG-like states at...

  17. Effects of Concentration and Conformation of Surfactants on Phase Separation of Surfactant-Water-Oil Systems

    Institute of Scientific and Technical Information of China (English)

    袁银权; 邹宪武; 刘昊阳

    2004-01-01

    The effects of surfactants on the phase separation of surfactant-water-oil systems have been investigated by using discontinuous molecular dynamic simulations. The phase separation speed and equilibrium configuration are dependent on the surfactant concentration and conformation. The equilibrium concentration of surfactants at the interface remains constant. With the increasing surfactant concentration, the equilibrium configuration crosses over from the disperse phase to the bicontinuous one. The crossover concentration is estimated. The conformation of the surfactant has little effect on the equilibrium concentration of surfactants at the interface,while it affects the equilibrium configuration after phase separation.

  18. Dispersion of denatured carbon nanotubes by using a dimethylformamide solution

    International Nuclear Information System (INIS)

    The dispersion of carbon nanotubes (CNTs) in liquid plays an important role in fundamental research and applied science. The most common technique applied to disperse CNTs is ultrasonication. The surfactants used for CNT dispersion are ethanol, sodium dodecyl benzenesulfonate (SDBS), dodecyltrimethylammonium bromide (DATB), sodium dodecyl sulfate (SDS) and sodium dodecylbenzene sulfonate (NaDDBS). This paper presents the dispersion of denatured CNTs by using a dimethylformamide (DMF) solution. The DMF is adsorbed on the surface of the nanotubes by a hydrophobic or π–π interaction. Ultrasonication helps DMF debundle the nanotubes by Coulombic or hydrophilic interaction, allowing the Van der Waals forces among the individual nanotubes to be overcome. UV–Vis spectra of dispersed CNTs in solution showed a maximum at 260 nm and decreased from UV to near IR. The vibration properties of the carbon samples were characterized with Raman spectroscopy, which illustrated the D and G bands of denatured CNTs at 1354 and 1581 cm−1, respectively, different from the values of 1352 cm−1 and 1580 cm−1, respectively, for undenatured CNTs. Finally, the interaction between surfactants and nanotubes was studied by Fourier transform infrared spectroscopy (FTIR)

  19. 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...... hold promises for a wide range of biotechnological applications, such as protein synthesis, protein aggregation, etc., and may have implications for biological systems as well....

  20. Denaturation of proteins by SDS and tetraalkylammonium dodecyl sulfates.

    Science.gov (United States)

    Lee, Andrew; Tang, Sindy K Y; Mace, Charles R; Whitesides, George M

    2011-09-20

    This article describes the use of capillary electrophoresis (CE) to examine the influence of different cations (C(+); C(+) = Na(+) and tetra-n-alkylammonium, NR(4)(+), where R = Me, Et, Pr, and Bu) on the rates of denaturation of bovine carbonic anhydrase II (BCA) in the presence of anionic surfactant dodecylsulfate (DS(-)). An analysis of the denaturation of BCA in solutions of Na(+)DS(-) and NR(4)(+)DS(-) (in Tris-Gly buffer) indicated that the rates of formation of complexes of denatured BCA with DS(-) (BCA(D)-DS(-)(n,sat)) are indistinguishable and independent of the cation below the critical micellar concentration (cmc) and independent of the total concentration of DS(-) above the cmc. At concentrations of C(+)DS(-) above the cmc, BCA denatured at rates that depended on the cation; the rates decreased by a factor >10(4) in the order of Na(+) ≈ NMe(4)(+) > NEt(4)(+) > NPr(4)(+) > NBu(4)(+), which is the same order as the values of the cmc (which decrease from 4.0 mM for Na(+)DS(-) to 0.9 mM for NBu(4)(+)DS(-) in Tris-Gly buffer). The relationship between the cmc values and the rates of formation of BCA(D)-DS(-)(n,sat()) suggested that the kinetics of denaturation of BCA involve the association of this protein with monomeric DS(-) rather than with micelles of (C(+)DS(-))(n). A less-detailed survey of seven other proteins (α-lactalbumin, β-lactoglobulin A, β-lactoglobulin B, carboxypeptidase B, creatine phosphokinase, myoglobin, and ubiquitin) showed that the difference between Na(+)DS(-) and NR(4)(+)DS(-) observed with BCA was not general. Instead, the influence of NR(4)(+) on the association of DS(-) with these proteins depended on the protein. The selection of the cation contributed to the properties (including the composition, electrophoretic mobility, and partitioning behavior in aqueous two-phase systems) of aggregates of denatured protein and DS(-). These results suggest that the variation in the behavior of NR(4)(+)DS(-) with changes in R may be

  1. Modulating enzyme activity using ionic liquids or surfactants.

    Science.gov (United States)

    Goldfeder, Mor; Fishman, Ayelet

    2014-01-01

    One of the important strategies for modulating enzyme activity is the use of additives to affect their microenvironment and subsequently make them suitable for use in different industrial processes. Ionic liquids (ILs) have been investigated extensively in recent years as such additives. They are a class of solvents with peculiar properties and a "green" reputation in comparison to classical organic solvents. ILs as co-solvents in aqueous systems have an effect on substrate solubility, enzyme structure and on enzyme-water interactions. These effects can lead to higher reaction yields, improved selectivity, and changes in substrate specificity, and thus there is great potential for IL incorporation in biocatalysis. The use of surfactants, which are usually denaturating agents, as additives in enzymatic reactions is less reviewed in recent years. However, interesting modulations in enzyme activity in their presence have been reported. In the case of surfactants there is a more pronounced effect on the enzyme structure, as can be observed in a number of crystal structures obtained in their presence. For each additive and enzymatic process, a specific optimization process is needed and there is no one-fits-all solution. Combining ILs and surfactants in either mixed micelles or water-in-IL microemulsions for use in enzymatic reaction systems is a promising direction which may further expand the range of enzyme applications in industrial processes. While many reviews exist on the use of ILs in biocatalysis, the present review centers on systems in which ILs or surfactants were able to modulate and improve the natural activity of enzymes in aqueous systems. PMID:24281758

  2. Single DNA denaturation and bubble dynamics

    International Nuclear Information System (INIS)

    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.

  3. 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.

  4. 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.

  5. 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...

  6. HENRY'S LAW CONSTANTS AND MICELLAR PARTITIONING OF VOLATILE ORGANIC COMPOUNDS IN SURFACTANT SOLUTIONS

    Science.gov (United States)

    Partitioning of volatile organic compounds (VOCs) into surfactant micelles affects the apparent vapor-liquid equilibrium of VOCs in surfactant solutions. This partitioning will complicate removal of VOCs from surfactant solutions by standard separation processes. Headspace expe...

  7. Modulating the Substrate Selectivity of DNA Aptamers Using Surfactants.

    Science.gov (United States)

    Peterson, Amberlyn M; Jahnke, Frank M; Heemstra, Jennifer M

    2015-11-01

    Nucleic acid aptamers have a number of advantages compared to antibodies, including greater ease of production and increased thermal stability. We hypothesized that aptamers may also be capable of functioning in the presence of high concentrations of surfactants, which readily denature antibodies and other protein-based affinity reagents. Here we report the first systematic investigation into the compatibility of DNA aptamers with surfactants. We find that neutral and anionic surfactants have only a minor impact on the ability of aptamers to fold and bind hydrophilic target molecules. Additionally, we demonstrate that surfactants can be utilized to modulate the substrate binding preferences of aptamers, likely due to the sequestration of hydrophobic target molecules within micelles. The compatibility of aptamers with commonly used surfactants is anticipated to expand their scope of potential applications, and the ability to modulate the substrate binding preferences of aptamers using a simple additive provides a novel route to increasing their selectivity in analytical applications. PMID:26465173

  8. Aerosol delivery of synthetic lung surfactant

    Directory of Open Access Journals (Sweden)

    Frans J. Walther

    2014-05-01

    Full Text Available Background. Nasal continuous positive airway pressure (nCPAP is a widely accepted technique of non-invasive respiratory support in premature infants with respiratory distress syndrome due to lack of lung surfactant. If this approach fails, the next step is often intubation, mechanical ventilation (MV and intratracheal instillation of clinical lung surfactant. Objective. To investigate whether aerosol delivery of advanced synthetic lung surfactant, consisting of peptide mimics of surfactant proteins B and C (SP-B and SP-C and synthetic lipids, during nCPAP improves lung function in surfactant-deficient rabbits. Methods. Experimental synthetic lung surfactants were produced by formulating 3% Super Mini-B peptide (SMB surfactant, a highly surface active SP-B mimic, and a combination of 1.5% SMB and 1.5% of the SP-C mimic SP-Css ion-lock 1 (BC surfactant, with a synthetic lipid mixture. After testing aerosol generation using a vibrating membrane nebulizer and aerosol conditioning (particle size, surfactant composition and surface activity, we investigated the effects of aerosol delivery of synthetic SMB and BC surfactant preparations on oxygenation and lung compliance in saline-lavaged, surfactant-deficient rabbits, supported with either nCPAP or MV. Results. Particle size distribution of the surfactant aerosols was within the 1–3 µm distribution range and surfactant activity was not affected by aerosolization. At a dose equivalent to clinical surfactant therapy in premature infants (100 mg/kg, aerosol delivery of both synthetic surfactant preparations led to a quick and clinically relevant improvement in oxygenation and lung compliance in the rabbits. Lung function recovered to a greater extent in rabbits supported with MV than with nCPAP. BC surfactant outperformed SMB surfactant in improving lung function and was associated with higher phospholipid values in bronchoalveolar lavage fluid; these findings were irrespective of the type of

  9. The Molecular Era of Surfactant Biology

    OpenAIRE

    Jeffrey A Whitsett

    2014-01-01

    Advances in the physiology, biochemistry, molecular and cell biology of the pulmonary surfactant system transformed the clinical care and outcome of preterm infants with respiratory distress syndrome. The molecular era of surfactant biology provided genetic insights into the pathogenesis of pulmonary disorders, previously termed “idiopathic” that affect newborn infants, children and adults. Knowledge related to the structure and function of the surfactant proteins and their roles in alveolar ...

  10. Denaturing Urea Polyacrylamide Gel Electrophoresis (Urea PAGE)

    OpenAIRE

    Summer, Heike; Grämer, René; Dröge, Peter

    2009-01-01

    Urea PAGE or denaturing urea polyacrylamide gel electrophoresis employs 6-8 M urea, which denatures secondary DNA or RNA structures and is used for their separation in a polyacrylamide gel matrix based on the molecular weight. Fragments between 2 to 500 bases, with length differences as small as a single nucleotide, can be separated using this method1. The migration of the sample is dependent on the chosen acrylamide concentration. A higher percentage of polyacrylamide resolves lower molecula...

  11. Irreversible thermal denaturation of Torpedo californica acetylcholinesterase.

    OpenAIRE

    Kreimer, D. I.; Shnyrov, V. L.; Villar, E.; Silman, I.; Weiner, L

    1995-01-01

    Thermal denaturation of Torpedo californica acetylcholinesterase, a disulfide-linked homodimer with 537 amino acids in each subunit, was studied by differential scanning calorimetry. It displays a single calorimetric peak that is completely irreversible, the shape and temperature maximum depending on the scan rate. Thus, thermal denaturation of acetylcholinesterase is an irreversible process, under kinetic control, which is described well by the two-state kinetic scheme N-->D, with activation...

  12. Reversibility of partial denaturation of DNA

    International Nuclear Information System (INIS)

    The recovery of hypochromicity in a partially denatured DNA sample when salt concentration is suddenly increased at a intermediate stage of the thermal transition is studied. The results of CsCl gradient analysis, PEG/DEX partition analysis, behaviour in a new thermal transition hydrodynamic properties and transforming ability, support the view that the process is an intramolecular double chain denaturation. The degree of denaturation irreversibility is dependent on single chain molecular weight of DNA (discontinuities denisty) and upon the helicity value at which salt concentration jump is performed. Both dependences are formally interpreted according to Elton's model for base distribution in DNA. Kinetically the process behaves as being an hydrodynamically limited rewinding. (author)

  13. Surfactant adsorption to soil components and soils.

    Science.gov (United States)

    Ishiguro, Munehide; Koopal, Luuk K

    2016-05-01

    Soils are complex and widely varying mixtures of organic matter and inorganic materials; adsorption of surfactants to soils is therefore related to the soil composition. We first discuss the properties of surfactants, including the critical micelle concentration (CMC) and surfactant adsorption on water/air interfaces, the latter gives an impression of surfactant adsorption to a hydrophobic surface and illustrates the importance of the CMC for the adsorption process. Then attention is paid to the most important types of soil particles: humic and fulvic acids, silica, metal oxides and layered aluminosilicates. Information is provided on their structure, surface properties and primary (proton) charge characteristics, which are all important for surfactant binding. Subsequently, the adsorption of different types of surfactants on these individual soil components is discussed in detail, based on mainly experimental results and considering the specific (chemical) and electrostatic interactions, with hydrophobic attraction as an important component of the specific interactions. Adsorption models that can describe the features semi-quantitatively are briefly discussed. In the last part of the paper some trends of surfactant adsorption on soils are briefly discussed together with some complications that may occur and finally the consequences of surfactant adsorption for soil colloidal stability and permeability are considered. When we seek to understand the fate of surfactants in soil and aqueous environments, the hydrophobicity and charge density of the soil or soil particles, must be considered together with the structure, hydrophobicity and charge of the surfactants, because these factors affect the adsorption. The pH and ionic strength are important parameters with respect to the charge density of the particles. As surfactant adsorption influences soil structure and permeability, insight in surfactant adsorption to soil particles is useful for good soil management. PMID

  14. Cold and Warm Denaturation of Proteins

    OpenAIRE

    Caldarelli, G.; De Los Rios, P.

    2001-01-01

    We introduce a simplified protein model where the water degrees of freedom appear explicitly (although in an extremely simplified fashion). Using this model we are able to recover both the warm and the cold protein denaturation within a single framework, while addressing important issues about the structure of model proteins.

  15. 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…

  16. Denaturant effects on HbGp hemoglobin as monitored by 8-anilino-1-naphtalene-sulfonic acid (ANS) probe.

    Science.gov (United States)

    Barros, Ana E B; Carvalho, Francisco A O; Alves, Fernanda R; Carvalho, José W P; Tabak, Marcel

    2015-03-01

    Glossoscolex paulistus extracellular hemoglobin (HbGp) stability has been monitored in the presence of denaturant agents. 8-Anilino-1-naphtalene-sulfonic acid (ANS) was used, and spectroscopic and hydrodynamic studies were developed. Dodecyltrimethylammonium bromide (DTAB) induces an increase in ANS fluorescence emission intensity, with maximum emission wavelength blue-shifted from 517 to 493 nm. Two transitions are noticed, at 2.50 and 9.50 mmol/L of DTAB, assigned to ANS interaction with pre-micellar aggregates and micelles, respectively. In oxy-HbGp, ANS binds to protein sites less exposed to solvent, as compared to DTAB micelles. In DTAB-HbGp-ANS ternary system, at pH 7.0, protein aggregation, oligomeric dissociation and unfolding were observed, while, at pH 5.0, aggregation is absent. DTAB induced unfolding process displays two transitions, one due to oligomeric dissociation and the second one, probably, to the denaturation of dissociated subunits. Moreover, guanidine hydrochloride and urea concentrations above 1.5 and 4.0 mol/L, respectively, induce the full HbGp denaturation, with reduction of ANS-bound oxy-HbGp hydrophobic patches, as noticed by fluorescence quenching up to 1.0 and 5.0 mol/L of denaturants. Our results show clearly the differences in probe sensitivity to the surfactant, in the presence and absence of protein, and new insights into the denaturant effects on HbGp unfolding. PMID:25546245

  17. Thermally cleavable surfactants

    Science.gov (United States)

    McElhanon, James R.; Simmons, Blake A.; Zifer, Thomas; Jamison, Gregory M.; Loy, Douglas A.; Rahimian, Kamyar; Long, Timothy M.; Wheeler, David R.; Staiger, Chad L.

    2006-04-04

    Two new surfactant molecules are reported which contain thermally labile Diels-Alder adducts connecting the polar and non-polar sections of each molecule. The two surfactants possess identical non-polar dodecyl tail segments but exhibit different polar headgroups. The surfactants become soluble in water when anionic salts are formed through the deprotonation of the surfactant headgroups by the addition of potassium hydroxide. When either surfactant is exposed to temperature above about 60.degree. C., the retro Diels-Alder reaction occurs, yielding hydrophilic and hydrophobic fragments and the aqueous solutions of the surfactants subsequently exhibit loss of all surface-active behavior.

  18. Effect of Freezing Rate on the Denaturation of Myofibrillar Protein in Fish Muscle

    Science.gov (United States)

    Yuan, Chunhong; Yu, Kefeng; Chen, Shunsheng; Cheng, Yudong; Zhou, Peigen; Konno, Kunihiko; Fukuda, Yutaka

    To elucidate the effect of freezing rate on the denaturation of myofibrillar protein, we employed a temperature programmable freezer to control the freezing rate. Freezing rates were set from 0.01 to 1 °C/min. Denaturation of myofibrillar protein was assessed by measuring Ca-, Mg-, EDTA(K)- ATPase activities and salt solubility. Freezing at all rates slightly reduced the Ca-ATPase activity, but the difference in the inactivation caused by quick (1°C/min) and slow (0.01°C/min) freezing was less than 12 %. Freezing enhanced the Mg-ATPase, and reduced the EDTA(K)-ATPase activities. The changes were a little greater for the samples frozen slowly indicating that change in the interaction between myosin and actin was modified when frozen slowly. No decrease in the salt solubility was detected for the samples at any freezing rates. The samples were subsequently frozen stored at various temperatures. Myosin denaturation progressed slowly during the storage, and the rate was strongly dependent on the storage temperature. Therefore, it was concluded that freezing rate slightly affected the denaturation of myofibrillar proteins, and storage temperature more severely affected the denaturation.

  19. DNA denatures upon drying after ethanol precipitation.

    OpenAIRE

    Svaren, J; Inagami, S; Lovegren, E; Chalkley, R

    1987-01-01

    We have observed that ethanol precipitation and subsequent drying of small (less than 400 bp) radiolabelled DNA fragments is able to induce a transition to a form that migrates aberrantly on acrylamide gels. This unusual form has increased sensitivity to S1 nuclease, decreased sensitivity to restriction enzymes, and a concentration dependence for the reversion to the duplex form. Apparently, DNA denatures upon dehydration so that redissolving at low dilution will allow the collapse of DNA fra...

  20. Thermal denaturation of an helicoidal DNA model

    OpenAIRE

    Barbi, Maria; Lepri, Stefano; Peyrard, Michel; Theodorakopoulos, Nikos

    2003-01-01

    We study the static and dynamical properties of DNA in the vicinity of its melting transition, i.e. the separation of the two strands upon heating. The investigation is based on a simple mechanical model which includes the helicoidal geometry of the molecule and allows an exact numerical evaluation of its thermodynamical properties. Dynamical simulations of long-enough molecular segments allow the study of the structure factors and of the properties of the denaturated regions. Simulations of ...

  1. Thermal Denaturation of Proteins and Chemical Equilibrium

    OpenAIRE

    Moroni, Laura; Gellini, Cristina; Remigio Salvi, Pier

    2015-01-01

    The thermal denaturation of proteins is considered as a process by means of which chemical equilibrium can be introduced to undergraduate students of Chemistry related curricula. In this approach chemical potential μ, Gibbs energy G, degree of advancement ξ and Le Châtelier principle are integrated with chemical equilibrium. With reference to α-Chymotrypsinogen A as a test case, the process is discussed in terms of a simplified two-state model. The activity is addressed to physical chemistry ...

  2. Exploring the denaturation of whey proteins upon application of moderate electric fields : a kinetic and thermodynamic study

    OpenAIRE

    Pereira, Ricardo; Teixeira, J.A.; Vicente, A.A.

    2011-01-01

    Thermal processing often results in disruption of the native conformation of whey proteins, thus affecting functional properties. The aim of this work was to evaluate the effects of moderate electric fields on denaturation kinetics and thermodynamic properties of whey protein dispersions at temperatures ranging from 75 to 90 °C. Application of electric fields led to a lower denaturation of whey proteins, kinetically traduced by lower values of reaction order (n) and rate constant (k) (p < 0.0...

  3. Lung surfactants and different contributions to thin film stability.

    Science.gov (United States)

    Hermans, Eline; Bhamla, M Saad; Kao, Peter; Fuller, Gerald G; Vermant, Jan

    2015-11-01

    The surfactant lining the walls of the alveoli in the lungs increases pulmonary compliance and prevents collapse of the lung at the end of expiration. In premature born infants, surfactant deficiency causes problems, and lung surfactant replacements are instilled to facilitate breathing. These pulmonary surfactants, which form complex structured fluid-fluid interfaces, need to spread with great efficiency and once in the alveolus they have to form a thin stable film. In the present work, we investigate the mechanisms affecting the stability of surfactant-laden thin films during spreading, using drainage flows from a hemispherical dome. Three commercial lung surfactant replacements Survanta, Curosurf and Infasurf, along with the phospholipid dipalmitoylphosphatidylcholine (DPPC), are used. The surface of the dome can be covered with human alveolar epithelial cells and experiments are conducted at the physiological temperature. Drainage is slowed down due to the presence of all the different lung surfactant replacements and therefore the thin films show enhanced stability. However, a scaling analysis combined with visualization experiments demonstrates that different mechanisms are involved. For Curosurf and Infasurf, Marangoni stresses are essential to impart stability and interfacial shear rheology does not play a role, in agreement with what is observed for simple surfactants. Survanta, which was historically the first natural surfactant used, is rheologically active. For DPPC the dilatational properties play a role. Understanding these different modes of stabilization for natural surfactants can benefit the design of effective synthetic surfactant replacements for treating infant and adult respiratory disorders. PMID:26307946

  4. Denaturation of circular DNA: Supercoils and overtwist

    OpenAIRE

    Kabakçıoğlu, Alkan; Bar, Amir ; Mukamel, David

    2012-01-01

    PHYSICAL REVIEW E 86, 061904 (2012) Denaturation of circular DNA: Supercoils and overtwist Amir Bar,1,2 Alkan Kabakc¸ıo˘glu,3 and David Mukamel1 1Department of Physics of Complex Systems, The Weizmann Institute of Science, Rehovot 76100, Israel 2Department of Computer Science and Applied Mathematics, The Weizmann Institute of Science, Rehovot 76100, Israel 3Department of Physics, Koc¸ University, Sarıyer 34450 ˙Istanbul, Turkey (Received 30 July 2012; published 11 December 2...

  5. Hemichrome formation during hemoglobin Zurich denaturation

    International Nuclear Information System (INIS)

    Electron paramagnetic resonance (EPR)spectrum of hemoglobin Zurich, after oxidation, storage and heating, showed several absorption derives in the high field region (g ≅ 2) which are indicative of hemichrome formation. Characteristic visible spectra of hemichromes were observed for oxidized Hb Zurich and for its spontaneous precipitate. The proportional increase of EPR signals at g ≅ 2 and decrease at g = 6.37, the constant ratio of absorbance at 540 nm to 280 nm during heating, and the similarity of this ratio for spontaneously precipitated HbA and for Hb Zurich indicate that heme is not lost during the first steps of Hb Zurich denaturation. (author)

  6. Antinociceptive and Anti-Inflammatory Effects of Orally Administrated Denatured Naja Naja Atra Venom on Murine Rheumatoid Arthritis Models

    Directory of Open Access Journals (Sweden)

    Kou-Zhu Zhu

    2013-01-01

    Full Text Available To investigate the antinociceptive and anti-inflammatory activities of the denatured Naja Naja atra venom (NNAV in rheumatoid arthritis-associated models, the denatured NNAV (heat treated; 30, 90, 270 μg/kg, the native NNAV (untreated with heat; 90 μg/kg, and Tripterygium wilfordii polyglycoside (TWP, 15 mg/kg were administrated orally either prophylactically or therapeutically. We measured time of licking the affected paw in formaldehyde-induced inflammatory model, paw volume in egg-white-induced inflammation, and granuloma weight in formalin-soaked filter paper-induced granuloma. For adjuvant-induced arthritis (AIA rats, paw edema, mechanical withdrawal threshold, serum levels of TNF-α and IL-10, and histopathological changes of the affected paw were assessed. We found that the denatured NNAV (90, 270 μg/kg significantly reduced time of licking paw, paw volume, and granuloma weight in above inflammatory models and also attenuated paw edema, mechanical hyperalgesia, and histopathology changes in AIA rats. Additionally, the increase in serum TNF-α and the decrease in serum IL-10 in AIA rats were reversed by the denatured NNAV. Although the native NNAV and TWP rendered the similar pharmacological actions on the above four models with less potency than that of the denatured NNAV, these findings demonstrate that oral administration of the denatured NNAV produces antinociceptive and anti-inflammatory activities on rheumatoid arthritis.

  7. Effect of Headgroup on DNA−Cationic Surfactant Interactions

    OpenAIRE

    Dasgupta, Antara; Das, Prasanta Kumar; Dias, Rita S.; Miguel, Maria G.; Lindman, Björn; Jadhav, Vaibhav M.; Gnanamani, Muthaiah; Maiti, Souvik

    2007-01-01

    The interaction behavior of DNA with different types of hydroxylated cationic surfactants has been studied. Attention was directed to how the introduction of hydroxyl substituents at the headgroup of the cationic surfactants affects the compaction of DNA. The DNA−cationic surfactant interaction was investigated at different charge ratios by several methods like UV melting, ethidium bromide exclusion, and gel electrophoresis. Studies show that there is a discrete transition in the DNA chain fr...

  8. Surfactant administration in neonates: A review of delivery methods

    OpenAIRE

    Nouraeyan, Nina; Lambrinakos-Raymond, Alicia; Leone, Marisa; Sant’Anna, Guilherme

    2014-01-01

    Surfactant has revolutionized the treatment of respiratory distress syndrome and some other respiratory conditions that affect the fragile neonatal lung. Despite its widespread use, the optimal method of surfactant administration in preterm infants has yet to be clearly determined. The present article reviews several aspects of administration techniques that can influence surfactant delivery into the pulmonary airways: the bolus volume, injection rate, gravity and orientation, ventilation str...

  9. 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.

  10. Surfactant phospholipid metabolism

    OpenAIRE

    Agassandian, Marianna; Mallampalli, Rama K.

    2012-01-01

    Pulmonary surfactant is essential for life and is comprised of a complex lipoprotein-like mixture that lines the inner surface of the lung to prevent alveolar collapse at the end of expiration. The molecular composition of surfactant depends on highly integrated and regulated processes involving its biosynthesis, remodeling, degradation, and intracellular trafficking. Despite its multicomponent composition, the study of surfactant phospholipid metabolism has focused on two predominant compone...

  11. Surfactants in tribology

    CERN Document Server

    Biresaw, Girma

    2014-01-01

    Surface science and tribology play very critical roles in many industries. Manufacture and use of almost all consumer and industrial products rely on the application of advanced surface and tribological knowledge. The fourth in a series, Surfactants in Tribology, Volume 4 provides an update on research and development activities connecting surfactants and tribological phenomena. Written by renowned subject matter experts, the book demonstrates how improved design of surfactants can be harnessed to control tribological phenomena. Profusely illustrated and copiously referenced, the chapters also

  12. Conformational stability of dimeric proteins: quantitative studies by equilibrium denaturation.

    OpenAIRE

    Neet, K. E.; Timm, D. E.

    1994-01-01

    The conformational stability of dimeric globular proteins can be measured by equilibrium denaturation studies in solvents such as guanidine hydrochloride or urea. Many dimeric proteins denature with a 2-state equilibrium transition, whereas others have stable intermediates in the process. For those proteins showing a single transition of native dimer to denatured monomer, the conformational stabilities, delta Gu (H2O), range from 10 to 27 kcal/mol, which is significantly greater than the conf...

  13. POLYMERIC SURFACTANT STRUCTURE

    Institute of Scientific and Technical Information of China (English)

    P.M. Saville; J.W. White

    2001-01-01

    Polymeric surfactants are amongst the most widespread of all polymers. In nature, proteins and polysaccharides cause self organization as a result of this surfactancy; in industry, polymeric surfactants play key roles in the food, explosives and surface coatings sectors. The generation of useful nano- and micro-structures in films and emulsions as a result of polymer amphiphilicity and the application of mechanical stress is discussed. The use of X-ray and neutron small angle scattering and reflectivity to measure these structures and their dynamic properties will be described. New results on linear and dendritic polymer surfactants are presented.

  14. Surfactant Sector Needs Urgent Readjustment

    Institute of Scientific and Technical Information of China (English)

    Huang Hongzhou

    2007-01-01

    @@ Surfactant industrial system has been basically established After 50 years' development, China has already established a surfactant industrial system with a relatively complete product portfolio and can produce 4714 varieties of surfactants in cationic,anionic, nonionic and amphoteric categories.

  15. Hot foam for weed control-Do alkyl polyglucoside surfactants used as foaming agents affect the mobility of organic contaminants in soil?

    Science.gov (United States)

    Cederlund, H; Börjesson, E

    2016-08-15

    Use of alkyl polyglucosides (APGs) as a foaming agent during hot water weed control may influence the environmental fate of organic contaminants in soil. We studied the effects of the APG-based foaming agent NCC Spuma (C8-C10) on leaching of diuron, glyphosate, and polycyclic aromatic hydrocarbons (PAHs) in sand columns. We also examined how APG concentration affected the apparent water solubility and adsorption of the herbicides and of the PAHs acenaphthene, acenaphthylene and fluorene. Application of APGs at the recommended concentration of 0.3% did not significantly affect leaching of any of the compounds studied. However, at a concentration of 1.5%, leaching of both diuron and glyphosate was significantly increased. The increased leaching corresponded to an increase in apparent water solubility of diuron and a decrease in glyphosate adsorption to the sand. However, APG addition did not significantly affect the mobility of PAHs even though their apparent water solubility was increased. These results suggest that application of APG-based foam during hot water weed control does not significantly affect the mobility of organic contaminants in soil if used according to recommendations. Moreover, they suggest that APGs could be useful for soil bioremediation purposes if higher concentrations are used. PMID:27149400

  16. Role of Silicone Surfactant in Flexible Polyurethane Foam.

    Science.gov (United States)

    Zhang; Macosko; Davis; Nikolov; Wasan

    1999-07-15

    Grafted copolymers which consist of a polydimethylsiloxane backbone and polyethylene oxide-co-propylene oxide pendant groups are used as surfactants to stabilize the foam cells in the flexible polyurethane foaming process. The mechanical properties of the cured polyurethane foam such as air permeability and foam cell size are affected significantly by the structure of the silicone surfactant used in the formulation. It is shown that silicone surfactant has an important impact on both the bubble generation and the cell window stabilization stage. A series of silicone surfactants with different structures was tested. Surfactants with higher silicone content will provide lower surface tension and thus help increase the number of air bubbles introduced during mixing. These air bubbles serve as the starting point for foam cell growth. As a result, the cured polyurethane foam made with higher silicone content surfactant has a smaller bubble size. It is also shown that silicone surfactant can reduce the cell window drainage rate due to the surface tension gradient along the cell window. The Gibbs film elasticity, the dynamic film elasticity, and the film drainage rate were measured for the first time versus surfactant composition. Surfactants with longer siloxane backbones are shown to give higher film elasticity. Using the vertical film drainage and foam column tests, it is shown that surfactants with higher film elasticity will yield slower drainage rate and better foam cell stability. Copyright 1999 Academic Press. PMID:10419661

  17. Pulmonary surfactant proteins and polymer combinations reduce surfactant inhibition by serum

    OpenAIRE

    Lu, Karen W.; Pérez-Gil, Jesús; Echaide, Mercedes; Taeusch, H. William

    2011-01-01

    Acute respiratory distress syndrome (ARDS) is an inflammatory condition that can be associated with capillary leak of serum into alveoli causing inactivation of surfactant. Resistance to inactivation is affected by types and concentrations of surfactant proteins, lipids, and polymers. Our aim was to investigate the effects of different combinations of these three components. A simple lipid mixture (DPPC/POPG) or a more complex lipid mixture (DPPC/POPC/POPG/cholesterol) was used. Native surfac...

  18. Dynamic covalent surfactants

    NARCIS (Netherlands)

    Minkenberg, C.B.

    2012-01-01

    In this thesis the development of surfactant aggregates with fast exchange dynamics between the aggregated and non-aggregated state is described. Dynamic surfactant exchange plays an important role in natural systems, for instance in cell signaling, cell division, and uptake and release of cargo. Re

  19. Fundamentals of surfactant sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Hofsaess, Hans [Second Institute of Physics, Georg-August University Goettingen, Friedrich-Hund-Platz 1, 37077 Goettingen (Germany)], E-mail: hans.hofsaess@phys.uni-goettingen.de; Zhang Kun [Second Institute of Physics, Georg-August University Goettingen, Friedrich-Hund-Platz 1, 37077 Goettingen (Germany)

    2009-08-15

    We introduce a new sputter technique, utilizing the steady-state coverage of a substrate surface with up to 10{sup 16} cm{sup -2} of foreign atoms simultaneously during sputter erosion by combined ion irradiation and atom deposition. These atoms strongly modify the substrate sputter yield on atomic to macroscopic length scales and therefore act as surfactant atoms (a blend of 'surface active agent'). Depending on the surfactant-substrate combination, the novel technique allows enhanced surface smoothing, generation of novel surface patterns, shaping of surfaces and formation of ultra-thin films. Sputter yield attenuation is demonstrated for sputtering of Si and Fe substrates and different surfactant species using 5 keV Xe ions at different incidence angles and fluences up to 10{sup 17} cm{sup -2}. Analytical approaches and Monte Carlo simulations are used to predict the sputtering yield attenuation as function of surfactant coverage. For sputtering of Si with Au surfactants we observe high sputter yields despite a steady-state surfactant coverage, which can be explained by strong ion-induced interdiffusion of substrate and surfactant atoms and the formation of a buried Au{sub x}Si surfactant layer in dynamic equilibrium.

  20. Fundamentals of surfactant sputtering

    International Nuclear Information System (INIS)

    We introduce a new sputter technique, utilizing the steady-state coverage of a substrate surface with up to 1016 cm-2 of foreign atoms simultaneously during sputter erosion by combined ion irradiation and atom deposition. These atoms strongly modify the substrate sputter yield on atomic to macroscopic length scales and therefore act as surfactant atoms (a blend of 'surface active agent'). Depending on the surfactant-substrate combination, the novel technique allows enhanced surface smoothing, generation of novel surface patterns, shaping of surfaces and formation of ultra-thin films. Sputter yield attenuation is demonstrated for sputtering of Si and Fe substrates and different surfactant species using 5 keV Xe ions at different incidence angles and fluences up to 1017 cm-2. Analytical approaches and Monte Carlo simulations are used to predict the sputtering yield attenuation as function of surfactant coverage. For sputtering of Si with Au surfactants we observe high sputter yields despite a steady-state surfactant coverage, which can be explained by strong ion-induced interdiffusion of substrate and surfactant atoms and the formation of a buried AuxSi surfactant layer in dynamic equilibrium.

  1. Reversible thermal denaturation of immobilized rhodanese

    International Nuclear Information System (INIS)

    For the first time, the enzyme rhodanese had been refolded after thermal denaturation. This was previously not possible because of the strong tendency for the soluble enzyme to aggregate at temperatures above 37 degrees C. The present work used rhodanese that was covalently coupled to a solid support under conditions that were found to preserve enzyme activity. Rhodanese was immobilized using an N-hydroxymalonimidyl derivative of Sepharose containing a 6-carbon spacer. The number of immobilized competent active sites was measured by using [35S]SO3(2-) to form an active site persulfide that is the obligatory catalytic intermediate. Soluble enzyme was irreversibly inactivated in 10 min at 52 degrees C. The immobilized enzyme regained at least 30% of its original activity even after boiling for 20 min. The immobilized enzyme had a Km and Vmax that were each approximately 3 times higher than the corresponding values for the native enzyme. After preincubation at high temperatures, progress curves for the immobilized enzyme showed induction periods of up to 5 min before attaining apparently linear steady states. The pH dependence of the activity was the same for both the soluble and the immobilized enzyme. These results indicate significant stabilization of rhodanese after immobilization, and instabilities caused by adventitious solution components are not the sole reasons for irreversibility of thermal denaturation seen with the soluble enzyme. The results are consistent with models for rhodanese that invoke protein association as a major cause of inactivation of the enzyme. Furthermore, the induction period in the progress curves is consistent with studies which show that rhodanese refolding proceeds through intermediate states

  2. Adaptations to hibernation in lung surfactant composition of 13-lined ground squirrels influence surfactant lipid phase segregation properties.

    Science.gov (United States)

    Suri, Lakshmi N M; Cruz, Antonio; Veldhuizen, Ruud A W; Staples, James F; Possmayer, Fred; Orgeig, Sandra; Perez-Gil, Jesus

    2013-08-01

    Pulmonary surfactant lines the entire alveolar surface, serving primarily to reduce the surface tension at the air-liquid interface. Surfactant films adsorb as a monolayer interspersed with multilayers with surfactant lipids segregating into different phases or domains. Temperature variation, which influences lipid physical properties, affects both the lipid phase segregation and the surface activity of surfactants. In hibernating animals, such as 13-lined ground squirrels, which vary their body temperature, surfactant must be functional over a wide range of temperatures. We hypothesised that surfactant from the 13-lined ground squirrel, Ictidomys tridecemlineatus, would undergo appropriate lipid structural re-arrangements at air-water interfaces to generate phase separation, sufficient to attain the low surface tensions required to remain stable at both low and high body temperatures. Here, we examined pressure-area isotherms at 10, 25 and 37°C and found that surfactant films from both hibernating and summer-active squirrels reached their highest surface pressure on the Wilhelmy-Langmuir balance at 10°C. Epifluorescence microscopy demonstrated that films of hibernating squirrel surfactant display different lipid micro-domain organisation characteristics than surfactant from summer-active squirrels. These differences were also reflected at the nanoscale as determined by atomic force microscopy. Such re-arrangement of lipid domains in the relatively more fluid surfactant films of hibernating squirrels may contribute to overcoming collapse pressures and support low surface tension during the normal breathing cycle at low body temperatures. PMID:23506681

  3. 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.

  4. Advances in reactive surfactants.

    Science.gov (United States)

    Guyot, A

    2004-05-20

    The study of reactive surfactants and their applications in the synthesis of latexes for waterborne coatings has been recently boosted by two successive European programmes, involving all together eight academic and five industrial laboratories. The most significant results were obtained using surfactants derived from maleic and related anhydrides, or both nonionic and anionic reactive polymeric surfactants. Such surfactants are able to improve the stability of styrenic and acrylic latexes vs. various constraints, such as electrolyte addition, freeze-thawing tests or extraction with alcohol or acetone. The properties of films used in waterborne coatings are also improved in case of water exposure (less water uptake, dimensional stability), as well as improved weatherability, and blocking properties. Formulations for woodstain varnishes, metal coating of printing inks, based on the use of simple polymerizable surfactants, are now in the market. PMID:15072924

  5. 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...

  6. 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...

  7. 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...

  8. Investigation of protein denaturation by nuclear magnetic relaxation method

    International Nuclear Information System (INIS)

    Proton spin-lattice relaxation times T1 for aqueous solutions of albumin from the white of a hen egg, as a function of temperature have been measured in the presence of thermal denaturation of the protein. The degree of the denaturation and the activation energies have been calculated from the experimental data. (author)

  9. Changes in protein dynamics induced under Gdn-HCl denaturation

    International Nuclear Information System (INIS)

    We have performed a study of protein dynamics in native and partially denatured horse-heart met-myoglobin (Mb-met) diluted in D2O. Protein dynamics is shown to be strongly solvent-dependent; in particular, higher degrees of macromolecular motions have been observed in the denatured states of Mb-met. (orig.)

  10. Interactions of cationic trimeric, gemini and monomeric surfactants with trianionic curcumin in aqueous solution.

    Science.gov (United States)

    Wang, Meina; Wu, Chunxian; Tang, Yongqiang; Fan, Yaxun; Han, Yuchun; Wang, Yilin

    2014-05-21

    Interactions of trianionic curcumin (Cur(3-)) with a series of cationic surfactants, monomeric surfactant dodecyl trimethylammonium bromide (DTAB), dimeric surfactant hexamethylene-1,6-bis(dodecyldimethylammonium bromide) (12-6-12) and trimeric surfactant tri(dodecyldimethylammonioacetoxy)diethyltriamine trichloride (DTAD), have been investigated in aqueous solution of pH 13.0. Surface tension and spectral measurements indicate that the cationic surfactants display a similar surfactant concentration dependent interaction process with Cur(3-), involving three interaction stages. At first the three cationic surfactants electrostatically bind on Cur(3-) to form the surfactant-Cur(3-) complex. Then the bound and unbound cationic surfactants with Cur(3-) aggregate into surfactant-Cur(3-) mixed micelles through hydrophobic interactions above the critical micelle concentration of the surfactants (CMCC) in the presence of Cur(3-). Finally excess unbound surfactants self-assemble into micelles like those without Cur(3-). For all the three surfactants, the addition of Cur(3-) only decreases the critical micelle concentration of 12-6-12 but does not affect the critical micelle concentration of DTAB and DTAD. As the oligomeric degree of surfactants increases, the intermolecular interaction of the cationic surfactants with Cur(3-) increases and the surfactant amount needed for Cur(3-) encapsulation decreases. Compared with 12-6-12, either the weaker interaction of DTAB with Cur(3-) or stronger interaction of DTAD with Cur(3-) limits the stability or solubility of Cur(3-) in surfactant micelles. Therefore, gemini surfactant 12-6-12 is the best choice to effectively suppress Cur(3-) degradation at very low concentrations. Isothermal titration microcalorimetry, surface tension and (1)H NMR results reveal that 12-6-12 and Cur(3-) form a (12-6-12)2-Cur(3-) complex and start to form micelles at extremely decreased concentrations, where either 12-6-12 or Cur(3-) works as a bridge

  11. Surfactant Effects on the Water-stable Aggregation of Wettable and Nonwettable Soils

    Science.gov (United States)

    Surfactants may affect soil structure differently, depending upon a soil’s wettability or the quality of rainfall or irrigation water. This study evaluated the effects of two nonionic surfactants and a surfactant-free water control on the water drop penetration time (WDPT) and mean weight diameter ...

  12. Guanidinium-Induced Denaturation by Breaking of Salt Bridges.

    Science.gov (United States)

    Meuzelaar, Heleen; Panman, Matthijs R; Woutersen, Sander

    2015-12-01

    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 a series of peptides containing Arg/Glu and Lys/Glu salt bridges that either stabilize or destabilize the folded conformation. The peptides containing stabilizing salt bridges are found to be denatured much more efficiently by Gdm(+) than the peptides containing destabilizing salt bridges. Complementary 2D-infrared measurements suggest a denaturation mechanism in which Gdm(+) binds to side-chain carboxylate groups involved in salt bridges. PMID:26490361

  13. Meconium Impairs Pulmonary Surfactant by a Combined Action of Cholesterol and Bile Acids

    OpenAIRE

    Lopez-Rodriguez, Elena; Echaide, Mercedes; Cruz, Antonio; Taeusch, H. William; Perez-Gil, Jesus

    2011-01-01

    Mechanisms for meconium-induced inactivation of pulmonary surfactant as part of the meconium aspiration syndrome in newborn infants, to our knowledge, are not clearly understood. Here we have studied the biophysical mechanisms of how meconium affects surface activity of pulmonary surfactant and whether the membrane-perturbing effects of meconium can be mimicked by exposure of surfactant to a mixture of bile acids and cholesterol. Surface activity of pulmonary surfactant complexes purified fro...

  14. Micellization properties of cardanol as a renewable co-surfactant.

    Science.gov (United States)

    Fontana, Antonella; Guernelli, Susanna; Zaccheroni, Nelsi; Zappacosta, Romina; Genovese, Damiano; De Crescentini, Lucia; Riela, Serena

    2015-09-21

    With the aim to improve the features of surfactant solutions in terms of sustainability and renewability we propose the use of hydrogenated natural and sustainable plant-derived cardanol as an additive to commercial surfactants. In the present study we demonstrated that its addition, in amounts as high as 10%, to commercial surfactants of different charge does not significantly affect surfactant properties. Conversely, the presence of hydrogenated cardanol can strongly affect spectrophotometric determination of CMC if preferential interactions with the dyes used take place. This latter evidence may be profitably exploited in surfactant manufacturing by considering that the concurrent presence of a rigid organic molecule such as Orange OT and 10% hydrogenated cardanol decreases the CMC of CTAB up to 65 times. PMID:26223697

  15. Metathesis depolymerizable surfactants

    Science.gov (United States)

    Jamison, Gregory M.; Wheeler, David R.; Loy, Douglas A.; Simmons, Blake A.; Long, Timothy M.; McElhanon, James R.; Rahimian, Kamyar; Staiger, Chad L.

    2008-04-15

    A class of surfactant molecules whose structure includes regularly spaced unsaturation in the tail group and thus, can be readily decomposed by ring-closing metathesis, and particularly by the action of a transition metal catalyst, to form small molecule products. These small molecules are designed to have increased volatility and/or enhanced solubility as compared to the original surfactant molecule and are thus easily removed by solvent extraction or vacuum extraction at low temperature. By producing easily removable decomposition products, the surfactant molecules become particularly desirable as template structures for preparing meso- and microstructural materials with tailored properties.

  16. Effects of Surfactant on Solubility and Microbial Conversion of Steroid

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    Enhancing the dispersion and dissolution of substrate particles in substrate/water suspension is a feasible way to improve steroid bioconversion. The aim of the present study is to investigate the effects of applying surfactant to microbial conversion system on the dispersion, solubilization and in turn bioconversion of steroid substrate. The model system is hydroxylation of substrate 16α-,17α-epoxy-4-pregnene-3,20-dine by microbial enzymes from Rhizopus nigricanl. The results show that the presence of substrate leads to an increase in critical micelle concentration (CMC) of surfactant PSE compared with the normal CMC of PSE in aqueous solution. The grinding time during substrate suspension preparation affects the substrate aqueous solubility differently with the varied surfactant concentrations while barely making any difference in substrate solubility in the absence of surfactant. The properly prolonged grinding time can make up for the loss in substrate solubility arising from the reduction in surfactant concentration. The surfactant complexes composed of surfactants PSE and MGE at appropriate ratios are screened out with orthodoxy experiment method, the interaction between PSE and MGE exerts the most prominent effects on substrate bioconversion, and the surfactant complexes show more beneficial effects on steroid bioconversion than the surfactant PSE used alone.

  17. Dilute Surfactant Methods for Carbonate Formations

    Energy Technology Data Exchange (ETDEWEB)

    Kishore K. Mohanty

    2006-02-01

    There are many fractured carbonate reservoirs in US (and the world) with light oil. Waterflooding is effective in fractured reservoirs, if the formation is water-wet. Many fractured carbonate reservoirs, however, are mixed-wet and recoveries with conventional methods are low (less than 10%). The process of using dilute anionic surfactants in alkaline solutions has been investigated in this work for oil recovery from fractured oil-wet carbonate reservoirs both experimentally and numerically. This process is a surfactant-aided gravity drainage where surfactant diffuses into the matrix, lowers IFT and contact angle, which decrease capillary pressure and increase oil relative permeability enabling gravity to drain the oil up. Anionic surfactants have been identified which at dilute concentration of 0.05 wt% and optimal salinity can lower the interfacial tension and change the wettability of the calcite surface to intermediate/water-wet condition as well or better than the cationic surfactant DTAB with a West Texas crude oil. The force of adhesion in AFM of oil-wet regions changes after anionic surfactant treatment to values similar to those of water-wet regions. The AFM topography images showed that the oil-wetting material was removed from the surface by the anionic surfactant treatment. Adsorption studies indicate that the extent of adsorption for anionic surfactants on calcite minerals decreases with increase in pH and with decrease in salinity. Surfactant adsorption can be minimized in the presence of Na{sub 2}CO{sub 3}. Laboratory-scale surfactant brine imbibition experiments give high oil recovery (20-42% OOIP in 50 days; up to 60% in 200 days) for initially oil-wet cores through wettability alteration and IFT reduction. Small (<10%) initial gas saturation does not affect significantly the rate of oil recovery in the imbibition process, but larger gas saturation decreases the oil recovery rate. As the core permeability decreases, the rate of oil recovery reduces

  18. Surfactant phospholipid metabolism.

    Science.gov (United States)

    Agassandian, Marianna; Mallampalli, Rama K

    2013-03-01

    Pulmonary surfactant is essential for life and is composed of a complex lipoprotein-like mixture that lines the inner surface of the lung to prevent alveolar collapse at the end of expiration. The molecular composition of surfactant depends on highly integrated and regulated processes involving its biosynthesis, remodeling, degradation, and intracellular trafficking. Despite its multicomponent composition, the study of surfactant phospholipid metabolism has focused on two predominant components, disaturated phosphatidylcholine that confers surface-tension lowering activities, and phosphatidylglycerol, recently implicated in innate immune defense. Future studies providing a better understanding of the molecular control and physiological relevance of minor surfactant lipid components are needed. This article is part of a Special Issue entitled Phospholipids and Phospholipid Metabolism. PMID:23026158

  19. Phosphine oxide surfactants revisited.

    Science.gov (United States)

    Stubenrauch, Cosima; Preisig, Natalie; Laughlin, Robert G

    2016-04-01

    This review summarizes everything we currently know about the nonionic surfactants alkyl dimethyl (C(n)DMPO) and alkyl diethyl (C(n)DEPO) phosphine oxide (PO surfactants). The review starts with the synthesis and the general properties (Section 2) of these compounds and continues with their interfacial properties (Section 3) such as surface tension, surface rheology, interfacial tension and adsorption at solid surfaces. We discuss studies on thin liquid films and foams stabilized by PO surfactants (Section 4) as well as studies on their self-assembly into lyotropic liquid crystals and microemulsions, respectively (Section 5). We aim at encouraging colleagues from both academia and industry to take on board PO surfactants whenever possible and feasible because of their broad variety of excellent properties. PMID:26869216

  20. Protein-surfactant interactions

    OpenAIRE

    Valstar, Ank

    2000-01-01

    Protein-surfactant interactions in aqueous media have been investigated. The globular proteins lysozyme and bovine serum albumin (BSA) served as model proteins. Several ionic and non-ionic surfactants were used. Fluorescence probe measurements showed that at low sodium dodecyl sulfate (SDS) concentration (< 0.1 M) one micelle-like SDS cluster is bound to lysozyme. From dynamic light scattering (DLS) results it was observed that lysozyme in the complex does not correspond to the fully unfol...

  1. Other indications for surfactant].

    OpenAIRE

    PROENÇA FERNANDES, E.; Carvalho, C; Silva, A.; Ferreira, P.; Alegria, A.; Lopes, L.; AREIAS, M.A.

    2002-01-01

    An Esp Pediatr. 2002 Jan;56(1):45-8. [Other indications for surfactant] [Article in Spanish] Proença Fernandes E, Carvalho C, Silva A, Ferreira P, Alegria A, Lopes L, Areias MA. Unidades de Cuidados Intensivos Neonatales y Pediátricos, Hospital Maria Pia, Spain. Abstract OBJECTIVE: The introduction of surfactant replacement therapy in the management of respiratory distress syndrome in the premature infant was a remarkable advance in neonatal intensive care. In the last few y...

  2. Pharmacoeconomics of Surfactant Therapy

    OpenAIRE

    Barbarello-Andrews, Liza; Marsh, Wallace

    2006-01-01

    Surfactant therapy has become an integral part of the standard of care for treating premature infants with respiratory distress syndrome (RDS). Institutions that routinely treat this patient population have to select a surfactant based upon clinical and pharmacoeconomic considerations. Pharmacoeconomic studies have established the cost-effectiveness of individual agents based on a variety of factors, including length of hospitalization, mortality odds ratio, and other direct medical costs. Th...

  3. Non Invasive Surfactant Application

    OpenAIRE

    Hacer Yapicioglu; Eren Kale Cekinmez; Ferda Ozlu

    2013-01-01

    Surfactant replacement therapy has been the mainstay of treatment for preterm infants with respiratory distress syndrome for more than twenty years. In recent years, the growing interest in noninvasive ventilation has led to novel approaches of administration. Non-invasive techniques of respiratory support were developed in order to reduce the adverse effects associated with ventilation via an endotracheal tube. Noninvasive surfactant administration technique during spontaneous breathing alon...

  4. Surfactant Driven Fracture of Interfacial Particle Rafts

    OpenAIRE

    Vella, Dominic; Kim, Ho-Young; Aussillous, Pascale; Mahadevan, L.

    2005-01-01

    We investigate the dynamic fracture of a close-packed monolayer of particles, or particle raft, floating at a liquid-gas interface induced by the localised addition of surfactant. Unusually for a two-dimensional solid, our experiments show that the speed of crack propagation here is not affected by the elastic properties of the raft. Instead it is controlled by the rate at which surfactant is advected to the crack tip by means of the induced Marangoni flows. Further, the velocity of propagati...

  5. Surfactant retention in Berea sandstone - effects of phase behavior and temperature

    Energy Technology Data Exchange (ETDEWEB)

    Novasad, J.

    1981-01-01

    This paper reports on laboratory investigations of surfactant retention in Berea cores. The principal objective is to evaluate the experimental techniques that can be used for measuring surfactant adsorption and to study experimentally two mechanisms responsible for surfactant retention. Specifically, an attempt is made to differentiate between the adsorption of surfactants at the solid-liquid interface and the retention of surfactants due to trapping in the immobile hydrocarbon phase that remains within the core following a surfactant flood. Results indicate that losses of surfactant caused by trapping in the immobile oil phase can be substantial and, more importantly, the minor changes in experimental conditions, such as variations in surfactant slug size, affect the measured losses substantially. 15 refs.

  6. Removal of cationic surfactant (CTAB from aqueous solution on to activated carbon obtained from corncob.

    Directory of Open Access Journals (Sweden)

    S. M. Yakout

    2009-05-01

    Full Text Available Direct and indirect releases of large quantities of surfactants to the environment may result in serious health and environmental problems. Therefore, surfactants should be removed from water before water is released to the environment or delivered for public use. Using powdered activated carbon (PAC as adsorbent may be an effective technique to remove surfactants. In this study, the removal of surfactants by PAC was investigated and the influencesof the operating parameters on the effectiveness on adsorption rate were studied. Cationic surfactant, Cetyl trimethyl ammonium bromide (CTAB was selected for the experiments. A series of batch experiments were performed to determine the sorption isotherms of surfactants to PAC. The results showed that carbon structure affect mainly on the surfactant adsorption. Surfactant equilibrium data fitted very well to the binary langmuir model. The pseudo first-,second- order and intraparticle diffusion kinetic models were applied. Both, the external mass transfer and intraparticle diffusion mechanisms involve in CTAB sorption.

  7. NMR spectroscopy of proteins encapsulated in a positively charged surfactant.

    Science.gov (United States)

    Lefebvre, Brian G; Liu, Weixia; Peterson, Ronald W; Valentine, Kathleen G; Wand, A Joshua

    2005-07-01

    Traditionally, large proteins, aggregation-prone proteins, and membrane proteins have been difficult to examine by modern multinuclear and multidimensional solution NMR spectroscopy. A major limitation presented by these protein systems is that their slow molecular reorientation compromises many aspects of the more powerful solution NMR methods. Several approaches have emerged to deal with the various spectroscopic difficulties arising from slow molecular reorientation. One of these takes the approach of actively seeking to increase the effective rate of molecular reorientation by encapsulating the protein of interest within the protective shell of a reverse micelle and dissolving the resulting particle in a low viscosity fluid. Since the encapsulation is largely driven by electrostatic interactions, the preparation of samples of acidic proteins suitable for NMR spectroscopy has been problematic owing to the paucity of suitable cationic surfactants. Here, it is shown that the cationic surfactant CTAB may be used to prepare samples of encapsulated anionic proteins dissolved in low viscosity solvents. In a more subtle application, it is further shown that this surfactant can be employed to encapsulate a highly basic protein, which is completely denatured upon encapsulation using an anionic surfactant. PMID:15949753

  8. 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.

  9. Purification of radiolabeled RNA products using denaturing gel electrophoresis

    OpenAIRE

    Adachi, Hironori; Yu, Yi-Tao

    2014-01-01

    This unit discusses a basic method for purification of radiolabeled RNAs using denaturing polyacrylamide gel electrophoresis. The method consists of a number of experimental procedures, including total RNA preparation from yeast cells, isolation of a specific RNA from total yeast RNA, RNA 3' terminal labeling using nucleotide (5’[32P]pCp) addition (via ligation), denaturing (8 M urea) polyacrylamide gel electrophoresis, and RNA extraction from the gel slice. Key points for achieving good elec...

  10. Heat denaturation of proteins from atlantic salmon (salmo salar)

    OpenAIRE

    Savitri, Sari

    2011-01-01

    Foods preserved by heat treatment have to meet several food safety. These criteria requirements are not easy to meet, as heat causes protein denaturation which is considered to be the one of the main reasons for quality changes in fish muscle. On the other hand consumers demand for fresh or fresh-like and minimally processed foods but also consider microbial safety and shelf life. Denaturation of proteins in Atlantic salmon was studied by differential scanning calorimetry at a consta...

  11. Possible mechanism for cold denaturation of proteins at high pressure

    International Nuclear Information System (INIS)

    We study cold denaturation of proteins at high pressures. Using multicanonical Monte Carlo simulations of a model protein in a water bath, we investigate the effect of water density fluctuations on protein stability. We find that above the pressure where water freezes to the dense ice phase (≅2 kbars) the mechanism for cold denaturation with decreasing temperature is the loss of local low-density water structure. We find our results in agreement with data of bovine pancreatic ribonuclease A

  12. Baseline length and automated fitting of denaturation data.

    OpenAIRE

    Allen, D. L.; Pielak, G. J.

    1998-01-01

    To understand relationships between protein sequence and stability, we often compare data from proteins that differ by the substitution of one amino acid. Frequently, an amino acid change causes the cooperative denaturation transitions to shift to lower temperatures, diminishing the signal from the native state. Here we show that apparent stability changes, i.e., the free energy of denaturation, deltaGD, can also be caused by a deficiency of points in the low temperature end of the transition...

  13. Manufacturing technology of irradiation denaturalized starch and its serosity performance

    International Nuclear Information System (INIS)

    Corn starch as raw material was irradiated by 60Co γ-rays to denaturalize and optimize the manufacturing condition. The serosity performance of the denaturalized corn starch, such as agglutinating strength, chorion, viscidity and the stability to heat, etc. were analyzed after irradiation treatment. Compared with chemical manufacturing technology, the irradiation method was much simpler and more environment friendly, Irradiated corn starch could meets the requirement of industrial application. (authors)

  14. Dynamical Transition in Hydrated Biomolecules, Native and Denatured

    International Nuclear Information System (INIS)

    We use elastic neutron scattering to demonstrate that a sharp increase in the mean-squared atomic displacements, commonly observed in hydrated proteins above 200 K and often referred to as the dynamical transition, is present in the hydrated state of both native and denatured lysozyme. A direct comparison of the native and denatured protein thus confirms that the presence of the transition in the mean-squared atomic displacements is not specific to biologically functional molecules.

  15. Surfactant administration in neonates: A review of delivery methods.

    Science.gov (United States)

    Nouraeyan, Nina; Lambrinakos-Raymond, Alicia; Leone, Marisa; Sant'Anna, Guilherme

    2014-01-01

    Surfactant has revolutionized the treatment of respiratory distress syndrome and some other respiratory conditions that affect the fragile neonatal lung. Despite its widespread use, the optimal method of surfactant administration in preterm infants has yet to be clearly determined. The present article reviews several aspects of administration techniques that can influence surfactant delivery into the pulmonary airways: the bolus volume, injection rate, gravity and orientation, ventilation strategies, alveolar recruitment, and viscosity and surface tension of the fluid instilled. Based on the present review, knowledge gaps regarding the best way to administer surfactant to neonates remain. From the available evidence, however, the most effective way to optimize surfactant delivery and obtain a more homogeneous distribution of the drug is by using rapid bolus instillation in combination with appropriate alveolar recruitment techniques. PMID:26078618

  16. Surfactant Proteins in Smoking-Related Lung Disease.

    Science.gov (United States)

    Papaioannou, Andriana I; Papiris, Spyridon; Papadaki, Georgia; Manali, Effrosyni D; Roussou, Aneza; Spathis, Aris; Karakitsos, Petros; Kostikas, Konstantinos

    2016-01-01

    Pulmonary surfactant is a highly surface-active mixture of proteins and lipids that is synthesized and secreted in the alveoli by type II epithelial cells and is found in the fluid lining the alveolar surface. The protein part of surfactant constitutes two hydrophilic proteins (SP-A and SP-D) that regulate surfactant metabolism and have immunologic functions, and two hydrophobic proteins (SP-B and SP-C), which play a direct role in the organization of the surfactant structure in the interphase and in the stabilization of the lipid layers during the respiratory cycle. Several studies have shown that cigarette smoke seems to affect, in several ways, both surfactant homeostasis and function. The alterations in surfactants' biophysical properties caused by cigarette smoking, contribute to the development of several smoking related lung diseases. In this review we provide information on biochemical and physiological aspects of the pulmonary surfactant and on its possible association with the development of two major chronic diseases of the lung known to be related to smoking, i.e. chronic obstructive pulmonary disease (COPD) and idiopathic pulmonary fibrosis (IPF). Additional information on the possible role of surfactant protein alterations and/or dysfunction in the combination of these two conditions, recently described as combined pulmonary fibrosis and emphysema (CPFE) are also provided. PMID:26420367

  17. Non Invasive Surfactant Application

    Directory of Open Access Journals (Sweden)

    Hacer Yapicioglu

    2013-08-01

    Full Text Available Surfactant replacement therapy has been the mainstay of treatment for preterm infants with respiratory distress syndrome for more than twenty years. In recent years, the growing interest in noninvasive ventilation has led to novel approaches of administration. Non-invasive techniques of respiratory support were developed in order to reduce the adverse effects associated with ventilation via an endotracheal tube. Noninvasive surfactant administration technique during spontaneous breathing along with nasal continous positive airway pressure support successfully reduces the need for further respiratory support and bronchopulmonary dysplasia rate in very low birth weight infants. Here we reviewed the new approches ton surfactant administration. [Archives Medical Review Journal 2013; 22(4.000: 634-644

  18. Computer simulation study of folding thermodynamics and kinetics of proteins in osmolytes and denaturants

    International Nuclear Information System (INIS)

    In living cells, the presence of macromolecular crowders, such as osmolytes or denaturants, strongly affects the stability of folded proteins. The overall effects depend on the size, concentration, and chemical properties of the crowding agents. This work uses an all-atom G o-bar model of the Trp-cage in spherical solvents to probe the physical origin of protein stabilization/destabilization by osmolytes/denturants. The solvent quality is controlled by the solvent-protein contact εPS that can represent repulsive osmolytes (εPS > 0) or attractive denaturants (εPS < 0). The model is used to show that protein stabilization by osmolytes proceeds by an excluded volume, entropy-driven mechanism. Protein destabilization by denaturant is shown to be driven by changes in enthalpy. It is found that small osmolytes are the most effective stabilizer of proteins. Folding simulations of the Trp-cage in osmolytes observe a two-fold increase in folding rates, for small osmolytes. This is due to an osmolyte-induced shift to more compact unfolded protein conformations.

  19. 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. PMID:26941080

  20. BINDING ISOTHERMS SURFACTANT-PROTEINS

    OpenAIRE

    Elena Irina Moater; Cristiana Radulescu; Ionica Ionita

    2011-01-01

    The interactions between surfactants and proteins shows some similarities with interactions between surfactants and polymers, but the hydrophobic amphoteric nature of proteins and their secondary and tertiary structure components make them different from conventional polymer systems. Many studies from the past about surfactant - proteins bonding used the dialysis techniques. Other techniques used to determine the binding isotherm, included ultrafiltration, ultracentrifugation, potentiometry, ...

  1. 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

  2. Sublethal effect of agronomical surfactants on the spider Pardosa agrestis.

    Science.gov (United States)

    Niedobová, Jana; Hula, Vladimír; Michalko, Radek

    2016-06-01

    In addition to their active ingredients, pesticides contain also additives - surfactants. Use of surfactants has been increasing over the past decade, but their effects on non-target organisms, especially natural enemies of pests, have been studied only very rarely. The effect of three common agrochemical surfactants on the foraging behavior of the wolf spider Pardosa agrestis was studied in the laboratory. Differences in short-term, long-term, and overall cumulative predatory activities were investigated. We found that surfactant treatment significantly affected short-term predatory activity but had no effect on long-term predatory activity. The surfactants also significantly influenced the cumulative number of killed prey. We also found the sex-specific increase in cumulative kills after surfactants treatment. This is the first study showing that pesticide additives have a sublethal effect that can weaken the predatory activity of a potential biological control agent. More studies on the effects of surfactants are needed to understand how they affect beneficial organisms in agroecosystems. PMID:26878602

  3. Simple model of p H-induced protein denaturation

    Science.gov (United States)

    Hidaka, T.; Shimada, A.; Nakata, Y.; Kodama, H.; Kurihara, H.; Tokihiro, T.; Ihara, S.

    2015-07-01

    The p H-induced conformational changes of proteins are systematically studied in the framework of a hydrophobic-polar (HP) model, in which proteins are dramatically simplified as chains of hydrophobic (H) and polar (P) beads on a lattice. We express the electrostatic interaction, the principal driving force of p H-induced unfolding that is not included in the conventional HP model, as the repulsive energy term between P monomers. As a result of the exact enumeration of all of the 14- to 18-mers, it is found that lowest-energy states in many sequences change from single "native" conformations to multiple sets of "denatured" conformations with an increase in the electrostatic repulsion. The switching of the lowest-energy states occurs in quite a similar way to real proteins: it is almost always between two states, while in a small fraction of ≥16 -mers it is between three states. We also calculate the structural fluctuations for all of the denatured states and find that the denatured states contain a broad range of incompletely unfolded conformations, similar to "molten globule" states referred to in acid or alkaline denatured real proteins. These results show that the proposed model provides a simple physical picture of p H-induced protein denaturation.

  4. Surfactant retention in Berea sandstone - effects of phase behavior and temperature

    Energy Technology Data Exchange (ETDEWEB)

    Novosad, J.

    1981-01-01

    This study reports on laboratory investigations of surfactant retention in Berea cores with the main emphasis on the experimental differentiation between surfactant losses due to adsorption and those due to trapping in the immobile hydrocarbon phase left in the core after surfactant flooding. Surfactants investigated include pure sulfonate (Texas No. 1), petroleum sulfonate (TRS 10-80), and synthetic sulfonate (PDM 337) in systems forming lower and middle phase microemulsions. The temperature range studied was between 20 and 70 C. Results indicate that losses of surfactant caused by trapping in the immobile oil phase can be substantial and, more importantly, that minor changes in experimental conditions, such as variations in surfactant slug size, affect the measured losses substantially. Similar experiments may yield very different results in terms of total retention and, if the effects of the different types of surfactant losses cannot be experimentally determined, erroneous conclusions may be reached. 15 references.

  5. 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 and...... peaks in the intensity trace along the extended molecule. We demonstrate that this structure arises from the physics of local denaturation: statistical mechanical calculations of sequence-dependent melting probability can predict the barcode to be observed experimentally for a given sequence....... 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....

  6. On the physics of pressure denaturation of proteins

    International Nuclear Information System (INIS)

    We show that the entropic effect originating from the translational movement of water molecules plays critical roles in the pressure-induced denaturation of proteins. In our statistical-mechanical method, the partial molar volume governing the pressure dependence of the structural stability is expressed in terms of the two geometric measures of each protein structure, the excluded volume and the accessible surface area for water molecules, and a parameter related to the water-density profile entropically formed near its surface. An unfolded structure, which is shown to turn more stable than the native one at an elevated pressure, successfully features the experimentally observed denaturation. (letter to the editor)

  7. Protein Denaturation with Guanidinium: A 2D-IR Study

    OpenAIRE

    Huerta-Viga, Adriana; Woutersen, Sander

    2013-01-01

    Guanidinium (Gdm+) is a widely used denaturant, but it is still largely unknown how it operates at the molecular level. In particular, the effect of guanidinium on the different types of secondary structure motifs of proteins is at present not clear. Here, we use two-dimensional infrared spectroscopy (2D-IR) to investigate changes in the secondary structure of two proteins with mainly α-helical or β-sheet content upon addition of Gdm-13C15N3·Cl. We find that upon denaturation, the β-sheet pro...

  8. High-intensity focused ultrasound monitoring using harmonic motion imaging for focused ultrasound (HMIFU) under boiling or slow denaturation conditions.

    Science.gov (United States)

    Hou, Gary Y; Marquet, Fabrice; Wang, Shutao; Apostolakis, Iason-Zacharias; Konofagou, Elisa E

    2015-07-01

    Harmonic motion imaging for focused ultrasound (HMIFU) is a recently developed high-intensity focused ultrasound (HIFU) treatment monitoring method that utilizes an amplitude-modulated therapeutic ultrasound beam to induce an oscillatory radiation force at the HIFU focus and estimates the focal tissue displacement to monitor the HIFU thermal treatment. In this study, the performance of HMIFU under acoustic, thermal, and mechanical effects was investigated. The performance of HMIFU was assessed in ex vivo canine liver specimens (n = 13) under slow denaturation or boiling regimes. A passive cavitation detector (PCD) was used to assess the acoustic cavitation activity, and a bare-wire thermocouple was used to monitor the focal temperature change. During lesioning with slow denaturation, high quality displacements (correlation coefficient above 0.97) were observed under minimum cavitation noise, indicating the tissue initial-softening-then- stiffening property change. During HIFU with boiling, HMIFU monitored a consistent change in lesion-to-background displacement contrast (0.46 ± 0.37) despite the presence of strong cavitation noise due to boiling during lesion formation. Therefore, HMIFU effectively monitored softening-then-stiffening during lesioning under slow denaturation, and detected lesioning under boiling with a distinct change in displacement contrast under boiling in the presence of cavitation. In conclusion, HMIFU was shown under both boiling and slow denaturation regimes to be effective in HIFU monitoring and lesioning identification without being significantly affected by cavitation noise. PMID:26168177

  9. Reaction of Native and Denatured Brucella abortus (S19 Proteins with Antibody Using Affinity Chromatography and Immunoblotting

    Directory of Open Access Journals (Sweden)

    R. Karimi

    2005-01-01

    Full Text Available Western blotting or immunoblotting commonly use for study of reaction between antigens and antibodies. Denaturation of many proteins in immunoblotting can affect greatly the reactivity of antibodies and outcome of the procedure.In this study proteins of Brucella abortus (S19 was extracted by a mild method and reaction of the extracted proteins with serum of infected human and goat and immunized rabbit compared by affinity chromatography and immunoblotting. Gamma globulin (mostly IgG fraction of the sera was precipitated by half saturation of ammonium sulfate and linked to activated sepharose 4B. The extracted proteins were loaded on the affinity column. Attached proteins was eluted by low pH and analyzed by SDS-PAGE. Reaction of the total extract and eluted fractions with IgG fraction of sera was evaluated by Western blotting.Upon the results of affinity chromatography and immunoblotting, Brucella proteins can be classified in four groups: 1- The proteins that adsorbed to the affinity column and react with IgG in westernblotting. 2- Proteins that react with IgG in native state but no in denatured state. 3- Proteins that do not react with IgG in native state but react in denatured state. 4- Proteins that do not react with IgG in native and denatured state.

  10. Stabilizing and destabilizing protein surfactant-based foams in the presence of a chemical surfactant: Effect of adsorption kinetics.

    Science.gov (United States)

    Li, Huazhen; Le Brun, Anton P; Agyei, Dominic; Shen, Wei; Middelberg, Anton P J; He, Lizhong

    2016-01-15

    Stimuli-responsive protein surfactants promise alternative foaming materials that can be made from renewable sources. However, the cost of protein surfactants is still higher than their chemical counterparts. In order to reduce the required amount of protein surfactant for foaming, we investigated the foaming and adsorption properties of the protein surfactant, DAMP4, with addition of low concentrations of the chemical surfactant sodium dodecylsulfate (SDS). The results show that the small addition of SDS can enhance foaming functions of DAMP4 at a lowered protein concentration. Dynamic surface tension measurements suggest that there is a synergy between DAMP4 and SDS which enhances adsorption kinetics of DAMP4 at the initial stage of adsorption (first 60s), which in turn stabilizes protein foams. Further interfacial properties were revealed by X-ray reflectometry measurements, showing that there is a re-arrangement of adsorbed protein-surfactant layer over a long period of 1h. Importantly, the foaming switchability of DAMP4 by metal ions is not affected by the presence of SDS, and foams can be switched off by the addition of zinc ions at permissive pH. This work provides fundamental knowledge to guide formulation using a mixture of protein and chemical surfactants towards a high performance of foaming at a low cost. PMID:26433478

  11. [Effect of magnesium ions on heat denaturation of DNA].

    Science.gov (United States)

    Blagoĭ, Iu P; Sorokin, V A; Valeev, V A; Khomenko, S A; Gladchenko, G O

    1977-01-01

    The dependence of animal DNA denaturation on magnesium ion concentration has been studied in the range (10(-6)--10(-1) M with sodium ion content of 10(-3) and 10(-2) M. Special attention has been given to the effect of multivalent metallic impurities bound to DNA. An increase of DNA thermal stability has been shown to occur in the magnesium concentration rage of 10(-6)--10(-4) M. At concentrations exceeding 10(-3) M the T M begins to decrease. The dependence of the DNA melting range on magnesium ion concentration has a maximum at approximately 10(-5) M Mg2+. At low magnesium and sodium ion concentrations a strong asymmetry of the melting curves has been observed. This effect can be described in terms of the melting theory for DNA complexed with small molecules and is explained by magnesium ion redistribution from the denatured portions of DNA to native ones. The method for calculation of melting curves in the DNA-ligand system has been proposed. Studies of thermal denaturation parameters have been shown to be an effective method for the estimation of binding constants of ligands to native and denatured DNA. PMID:618320

  12. [Effect of divalent copper ions on heat denaturation of DNA].

    Science.gov (United States)

    Blagoĭ, Iu P; Sorokin, V A; Valeev, V A; Gladchenko, G O

    1978-01-01

    Using the thermal denaturation method the effect of bivalent copper of (4-10(-6)-10(-3)) M concentrations on the helix-coil transition of DNA was studied in the solution of Na+ concentrations 10(-3)-10(-1) M. Unlike the previous studies, this paper makes allowance for the effect of impurity ions present in DNA and deionized water. It has been shown that in the region of low Cu2+ and Na+ concentrations, thermal stability increases, the melting range extends and the denaturation curves become asymmetric. At concentrations more than approximately 3-10(-5) M Cu2+, melting temperature starts to fall, and the range reduces to 1-1.5 degrees at [Cu2+] greater than or equal to 2-10(-4) M. As [Cu2+] reaches these values, the denaturation curve asymmetry and melting range increase again, which is due to the inversion of the relative stability of AT- and GC-pairs. Employing experimental and phase-transition-theory data for homopolymers, the constants of Cu2+ binding with phosphates and DNA bases were calculated. The concentration dependence of the DNA denaturation parameters was shown to be governed by the superposition of binding Cu2+ with phosphates and nucleic acid bases. PMID:683190

  13. Denaturation of membrane proteins and hyperthermic cell killing

    OpenAIRE

    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 bound to membrane proteins, is capable of providing heat resistance to these proteins. ... Zie: Summary

  14. Denaturation and intermediates study of two sturgeon hemoglobins by n-dodecyl trimethylammonium bromide

    Science.gov (United States)

    Ariaeenejad, Shohreh; Habibi-Rezaei, Mehran; Kavousi, Kaveh; Jamili, Shahla; Fatemi, Mohammad Reza; Hong, Jun; Poursasan, Najmeh; Sheibani, Nader; Moosavi-Movahedi, Ali. A.

    2013-01-01

    Varieties of hemoglobin (Hb) forms exist in fish, which are usually well adapted to the different ecological conditions or various habitats. In the current study, Hbs from two Sturgeon species of the Southern Caspian Sea Basin were purified and studied upon interaction with n-dodecyl trimethylammonium bromide (DTAB; as a cationic surfactant) by various methods including UV-visible absorption, dynamic light scattering (DLS), and ANS fluorescence spectrophotometry. The chemometric analysis of Hbs was investigated upon interaction with DTAB under titration, using UV-visible absorption spectra. The chemometric resolution techniques were used to determine the number of the components and mole fraction of the oxidized Hbs. These results provided the evidence for the existence of three different molecular components including native (N), intermediate (I) and denatured (D) in sturgeon Hbs. According to the distribution of intermediates, which were broadened in a range of DTAB concentration, the aggregation states, DLS experiments, and thermal stability (Tm obtained by differential scanning calorimetry (DSC)), the Acipenser stellatus Hb was more stable compared to Acipenser persicus Hb. These results demonstrate a significant relationship between the stability of fish Hbs and the habitat depth requirements. PMID:23142155

  15. Clouding behaviour in surfactant systems.

    Science.gov (United States)

    Mukherjee, Partha; Padhan, Susanta K; Dash, Sukalyan; Patel, Sabita; Mishra, Bijay K

    2011-02-17

    A study on the phenomenon of clouding and the applications of cloud point technology has been thoroughly discussed. The phase behaviour of clouding and various methods adopted for the determination of cloud point of various surfactant systems have been elucidated. The systems containing anionic, cationic, nonionic surfactants as well as microemulsions have been reviewed with respect to their clouding phenomena and the effects of structural variation in the surfactant systems have been incorporated. Additives of various natures control the clouding of surfactants. Electrolytes, nonelectrolytes, organic substances as well as ionic surfactants, when present in the surfactant solutions, play a major role in the clouding phenomena. The review includes the morphological study of clouds and their applications in the extraction of trace inorganic, organic materials as well as pesticides and protein substrates from different sources. PMID:21296314

  16. Genetic Disorders of Surfactant Dysfunction

    OpenAIRE

    Wert, Susan E.; Whitsett, Jeffrey A.; Nogee, Lawrence M.

    2009-01-01

    Mutations in the genes encoding the surfactant proteins B and C (SP-B and SP-C) and the phospholipid transporter, ABCA3, are associated with respiratory distress and interstitial lung disease in the pediatric population. Expression of these proteins is regulated developmentally, increasing with gestational age, and is critical for pulmonary surfactant function at birth. Pulmonary surfactant is a unique mixture of lipids and proteins that reduces surface tension at the air-liquid interface, pr...

  17. Pulmonary Surfactant: An Immunological Perspective

    OpenAIRE

    Chroneos, Zissis C.; Sever-Chroneos, Zvjezdana; Shepherd, Virginia L.

    2009-01-01

    Pulmonary surfactant has two crucial roles in respiratory function; first, as a biophysical entity it reduces surface tension at the air water interface, facilitating gas exchange and alveolar stability during breathing, and, second, as an innate component of the lung's immune system it helps maintain sterility and balance immune reactions in the distal airways. Pulmonary surfactant consists of 90% lipids and 10% protein. There are four surfactant proteins named SP-A, SP-B, SP-C, and SP-D; th...

  18. Gemini surfactants as gene carriers

    Directory of Open Access Journals (Sweden)

    Teresa Piskorska

    2010-03-01

    Full Text Available Gemini surfactants are a new class of amphiphilic compounds built from two classic surfactant moieties bound together by a special spacer group. These compounds appear to be excellent for creating complexes with DNA and are effective in mediating transfection. Thanks to their construction, DNA carrier molecules built from gemini surfactants are able to deliver genes to cells of almost any DNA molecule size, unattainable when using viral gene delivery systems. Moreover, they are much safer for living organisms.

  19. Adsorption of polyhydroxyl based surfactants

    OpenAIRE

    Matsson, Maria

    2005-01-01

    Adsorption on solid surfaces from solution is a fundamental property of a surfactant. It might even be the most important aspect of surfactant behavior, since it influences many applications, such as cleaning, detergency, dispersion, separation, flotation, and lubrication. Consequently, fundamental investigations of surfactant adsorption are relevant to many areas. The main aim of this thesis has been to elucidate the adsorption properties, primarily on the solid/water interface, of a particu...

  20. Diseases of Pulmonary Surfactant Homeostasis

    OpenAIRE

    Jeffrey A Whitsett; Wert, Susan E.; Weaver, Timothy E.

    2015-01-01

    Advances in physiology and biochemistry have provided fundamental insights into the role of pulmonary surfactant in the pathogenesis and treatment of preterm infants with respiratory distress syndrome. Identification of the surfactant proteins, lipid transporters, and transcriptional networks regulating their expression has provided the tools and insights needed to discern the molecular and cellular processes regulating the production and function of pulmonary surfactant prior to and after bi...

  1. Surfactant-Mediated Growth Revisited

    International Nuclear Information System (INIS)

    The x-ray structure analysis of the oxygen-surfactant-mediated growth of Ni on Cu(001) identifies up to 0.15 monolayers of oxygen in subsurface octahedral sites. This questions the validity of the general view that surfactant oxygen floats on top of the growing Ni film. Rather, the surfactant action is ascribed to an oxygen-enriched zone extending over the two topmost layers. Surface stress measurements support this finding. Our results have important implications for the microscopic understanding of surfactant-mediated growth and the change of the magnetic anisotropy of the Ni films

  2. Reaction of Native and Denatured Brucella abortus (S19) Proteins with Antibody Using Affinity Chromatography and Immunoblotting

    OpenAIRE

    Karimi, R.; A Mostafaie; B. Tabaraie; Y. Bahrami; J. Abdolalizadeh

    2005-01-01

    Western blotting or immunoblotting commonly use for study of reaction between antigens and antibodies. Denaturation of many proteins in immunoblotting can affect greatly the reactivity of antibodies and outcome of the procedure.In this study proteins of Brucella abortus (S19) was extracted by a mild method and reaction of the extracted proteins with serum of infected human and goat and immunized rabbit compared by affinity chromatography and immunoblotting. Gamma globulin (m...

  3. Pulmonary surfactant protein A (SP-A) specifically binds dipalmitoylphosphatidylcholine

    International Nuclear Information System (INIS)

    Phospholipids are the major components of pulmonary surfactant. Dipalmitoylphosphatidylcholine is believed to be especially essential for the surfactant function of reducing the surface tension at the air-liquid interface. Surfactant protein A (SP-A) with a reduced denatured molecular mass of 26-38 kDa, characterized by a collagen-like structure and N-linked glycosylation, interacts strongly with a mixture of surfactant-like phospholipids. In the present study the direct binding of SP-A to phospholipids on a thin layer chromatogram was visualized using 125I-SP-A as a probe, so that the phospholipid specificities of SP-A binding and the structural requirements of SP-A and phospholipids for the binding could be examined. Although 125I-SP-A bound phosphatidylcholine and sphingomyeline, it was especially strong in binding dipalmitoylphosphatidylcholine, but failed to bind phosphatidylglycerol, phosphatidylinositol, phosphatidylethanolamine, and phosphatidylserine. Labeled SP-A also exhibited strong binding to distearoylphosphatidylcholine, but weak binding to dimyristoyl-, 1-palmitoyl-2-linoleoyl-, and dilinoleoylphosphatidylcholine. Unlabeled SP-A readily competed with labeled SP-A for phospholipid binding. SP-A strongly bound dipalmitoylglycerol produced by phospholipase C treatment of dipalmitoylphosphatidylcholine, but not palmitic acid. This protein also failed to bind lysophosphatidylcholine produced by phospholipase A2 treatment of dipalmitoylphosphatidylcholine. 125I-SP-A shows almost no binding to dipalmitoylphosphatidylglycerol and dipalmitoylphosphatidylethanolamine. The addition of 10 mM EGTA into the binding buffer reduced much of the 125I-SP-A binding to phospholipids. Excess deglycosylated SP-A competed with labeled SP-A for binding to dipalmitoylphosphatidylcholine, but the excess collagenase-resistant fragment of SP-A failed

  4. Correlated Parameter Fit of Arrhenius Model for Thermal Denaturation of Proteins and Cells

    OpenAIRE

    Qin, Zhenpeng; Balasubramanian, Saravana Kumar; Wolkers, Willem F.; Pearce, John A.; Bischof, John C.

    2014-01-01

    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 5...

  5. Protein denaturation in intact hepatocytes and isolated cellular organelles during heat shock

    OpenAIRE

    1993-01-01

    There is circumstantial evidence that protein denaturation occurs in cells during heat shock at hyperthermic temperatures and that denatured or damaged protein is the primary inducer of the heat shock response. However, there is no direct evidence regarding the extent of denaturation of normal cellular proteins during heat shock. Differential scanning calorimetry (DSC) is the most direct method of monitoring protein denaturation or unfolding. Due to the fundamental parameter measured, heat fl...

  6. Surfactant phosphatidylcholine metabolism and surfactant function in preterm, ventilated lambs

    International Nuclear Information System (INIS)

    Preterm lambs were delivered at 138 days gestational age and ventilated for periods up to 24 h in order to study surfactant metabolism and surfactant function. The surfactant-saturated phosphatidylcholine pool in the alveolar wash was 13 +/- 4 mumol/kg and did not change from 10 min to 24 h after birth. Trace amounts of labeled natural sheep surfactant were mixed with fetal lung fluid at birth. By 24 h, 80% of the label had become lung-tissue-associated, yet there was no loss of label from phosphatidylcholine in the lungs when calculated as the sum of the lung tissue plus alveolar wash. De novo synthesized phosphatidylcholine was labeled with choline given by intravascular injection at 1 h of age. Labeled phosphatidylcholine accumulated in the lung tissue linearly to 24 h, and the labeled phosphatidylcholine moved through lamellar body to alveolar pools. The turnover time for alveolar phosphatidylcholine was estimated to be about 13 h, indicating an active metabolic pool. A less surface-active surfactant fraction recovered as a supernatant after centrifugation of the alveolar washes at 40,000 x g increased from birth to 10 min of ventilation, but no subsequent changes in the distribution of surfactant phosphatidylcholine in surfactant fractions occurred. The results were consistent with recycling pathway(s) that maintained surface-active surfactant pools in preterm ventilated lambs

  7. Surfactant phosphatidylcholine metabolism and surfactant function in preterm, ventilated lambs

    Energy Technology Data Exchange (ETDEWEB)

    Jobe, A.H.; Ikegami, M.; Seidner, S.R.; Pettenazzo, A.; Ruffini, L.

    1989-02-01

    Preterm lambs were delivered at 138 days gestational age and ventilated for periods up to 24 h in order to study surfactant metabolism and surfactant function. The surfactant-saturated phosphatidylcholine pool in the alveolar wash was 13 +/- 4 mumol/kg and did not change from 10 min to 24 h after birth. Trace amounts of labeled natural sheep surfactant were mixed with fetal lung fluid at birth. By 24 h, 80% of the label had become lung-tissue-associated, yet there was no loss of label from phosphatidylcholine in the lungs when calculated as the sum of the lung tissue plus alveolar wash. De novo synthesized phosphatidylcholine was labeled with choline given by intravascular injection at 1 h of age. Labeled phosphatidylcholine accumulated in the lung tissue linearly to 24 h, and the labeled phosphatidylcholine moved through lamellar body to alveolar pools. The turnover time for alveolar phosphatidylcholine was estimated to be about 13 h, indicating an active metabolic pool. A less surface-active surfactant fraction recovered as a supernatant after centrifugation of the alveolar washes at 40,000 x g increased from birth to 10 min of ventilation, but no subsequent changes in the distribution of surfactant phosphatidylcholine in surfactant fractions occurred. The results were consistent with recycling pathway(s) that maintained surface-active surfactant pools in preterm ventilated lambs.

  8. Interaction of nonionic surfactant AEO9 with ionic surfactants

    Institute of Scientific and Technical Information of China (English)

    ZHANG Zhi-guo; YIN Hong

    2005-01-01

    The interaction in two mixtures of a nonionic surfactant AEO9 (C12H25O(CH2CH2O)9H) and different ionic surfactants was investigated. The two mixtures were AEO9/sodium dodecyl sulfate (SDS) and AEO9/cetyltrimethylammonium bromide (CTAB) at molar fraction of AEO9, αAEO9 =0.5. The surface properties of the surfactants, critical micelle concentration (CMC),effectiveness of surface tension reduction (γCMC), maximum surface excess concentration (Гmax) and minimum area per molecule at the air/solution interface (Amin) were determined for both individual surfactants and their mixtures. The significant deviations from ideal behavior (attractive interactions) of the nonionic/ionic surfactant mixtures were determined. Mixtures of both AEO9/SDS and AEO9/CTAB exhibited synergism in surface tension reduction efficiency and mixed micelle formation, but neither exhibited synergism in surface tension reduction effectiveness.

  9. 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. PMID:25840745

  10. Influence of liquid-layer thickness on pulmonary surfactant spreading and collapse.

    Science.gov (United States)

    Siebert, Trina A; Rugonyi, Sandra

    2008-11-15

    Pulmonary surfactant spreads on the thin ( approximately 0.1 microm) liquid layer that lines the alveoli, forming a film that reduces surface tension and allows normal respiration. Pulmonary surfactant deposited in vitro on liquid layers that are several orders of magnitude thicker, however, does not reach the low surface tensions ( approximately 0.001 N/m) achieved in the lungs during exhalation when the surfactant film compresses. This is due to collapse, a surface phase transition during which the surfactant film, rather than decreasing surface tension by increasing its surface density, becomes thicker at constant surface tension ( approximately 0.024 N/m). Formation of the collapse phase requires transport of surfactant to collapse sites, and this transport can be hindered in thinner liquid layers by viscous resistance to motion. Our objective is to determine the effect of the liquid-layer thickness on surfactant transport, which might affect surfactant collapse. To this end, we developed a mathematical model that accounts for the effect of the liquid-layer thickness on surfactant transport, and focused on surfactant spreading and collapse. Model simulations showed a marked decrease in collapse rates for thinner liquid layers, but this decrease was not enough to completely explain differences in surfactant film behavior between in vitro and in situ experiments. PMID:18676658

  11. NATURAL SURFACTANTS IN PAPER RECYCLING

    Science.gov (United States)

    The objective of this project is to introduce new types of surfactants based on renewable materials (sugar surfactants) for use in ink removal from recycled paper. By applying green chemistry approaches we not only will solve an important industry and environmental problem but...

  12. Genetics Home Reference: surfactant dysfunction

    Science.gov (United States)

    ... and decreased surfactant function. The loss of functional surfactant raises surface tension in the alveoli, causing severe breathing problems. The combination of SP-B and SP-C dysfunction may explain why the signs and symptoms of SP-B deficiency ... dysfunction sometimes called SP-C dysfunction. These mutations ...

  13. Novel Approaches to Surfactant Administration

    OpenAIRE

    Samir Gupta; Donn, Steven M.

    2012-01-01

    Surfactant replacement therapy has been the mainstay of treatment for preterm infants with respiratory distress syndrome for more than twenty years. For the most part, surfactant is administered intratracheally, followed by mechanical ventilation. In recent years, the growing interest in noninvasive ventilation has led to novel approaches of administration. This paper will review these techniques and the associated clinical evidence.

  14. Effect of mycolic acid on surface activity of binary surfactant lipid monolayers.

    Science.gov (United States)

    Chimote, G; Banerjee, R

    2008-12-15

    In pulmonary tuberculosis, Mycobacterium tuberculosis lies in close physical proximity to alveolar surfactant. Cell walls of the mycobacteria contain loosely bound, detachable surface-active lipids. In this study, the effect of mycolic acid (MA), the most abundant mycobacterial cell wall lipid, on the surface activity of phospholipid mixtures from lung surfactant was investigated using Langmuir monolayers and atomic force microscopy (AFM). In the presence of mycolic acid, all the surfactant lipid mixtures attained high minimum surface tensions (between 20 and 40 mN/m) and decreased surface compressibility moduli acid. Mycolic acids could aggregate within surfactant lipid monolayers and result in disturbed monolayer surface activity. The extent of the effect of mycolic acid depended on the initial state of the monolayer, with fluid films of DPPC-POPC and DPPC-CHOL being least affected. The results imply inhibitory effects of mycolic acid toward lung surfactant lipids and could be a mechanism of lung surfactant dysfunction in pulmonary tuberculosis. PMID:18848703

  15. Effect of different surfactants and thicknesses on electrodeposited films of bismuth telluride and its thermoelectric performance

    Science.gov (United States)

    Kulsi, Chiranjit; Mitra, Mousumi; Kargupta, Kajari; Ganguly, Saibal; Banerjee, Dipali; Goswami, Shyamaprosad

    2015-10-01

    Thin films of bismuth telluride using various surfactants such as sodium dodecyl sulfate (SDS) and polyvinylpyrrolidone (PVP) have been electrochemically deposited. The influence of different surfactants on crystal orientation and morphology was investigated and correlated with the thermoelectric performance of the electrodeposited films. Since thickness affects the thermoelectric performance compared to the surfactant, thickness- dependent thermoelectric performance has also been investigated. The carrier mobilities of the films obtained are significantly enhanced due to improved surface morphology using different surfactants. Between the two surfactants, films with SDS exhibited the higher value of thermoelectric power, power factor, and figure of merit, which is due to the effect of micelle formation. The XRD pattern of all the films, which are electrodeposited without surfactant or using SDS and PVP, showed preferred crystal orientation along the (018) direction. The roles of organic molecules in the development of nanoparticles with improved thermoelectric properties have been investigated.

  16. 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.

  17. Protein Denaturation with Guanidinium: A 2D-IR Study.

    Science.gov (United States)

    Huerta-Viga, Adriana; Woutersen, Sander

    2013-10-17

    Guanidinium (Gdm(+)) is a widely used denaturant, but it is still largely unknown how it operates at the molecular level. In particular, the effect of guanidinium on the different types of secondary structure motifs of proteins is at present not clear. Here, we use two-dimensional infrared spectroscopy (2D-IR) to investigate changes in the secondary structure of two proteins with mainly α-helical or β-sheet content upon addition of Gdm-(13)C(15)N3·Cl. We find that upon denaturation, the β-sheet protein shows a complete loss of β-sheet structure, whereas the α-helical protein maintains most of its secondary structure. These results suggest that Gdm(+) disrupts β-sheets much more efficiently than α-helices, possibly because in the former, hydrophobic interactions are more important and the number of dangling hydrogen bonds is larger. PMID:24163724

  18. 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.

  19. Contribution of Water to Pressure and Cold Denaturation of Proteins

    Science.gov (United States)

    Bianco, Valentino; Franzese, Giancarlo

    2015-09-01

    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.

  20. Influence of Ficoll on urea induced denaturation of fibrinogen

    Directory of Open Access Journals (Sweden)

    Kamatchi Sankaranarayanan

    2016-03-01

    Full Text Available 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.

  1. 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.

  2. Improving reseeding success after catastrophic wildfire with surfactant seed coating technology

    Science.gov (United States)

    The application of soil surfactants in wildfire-affected ecosystems has been limited due to logistical and economic constraints associated with the standard practice of using large quantities of irrigation water as the surfactant carrier. We tested a potential solution to this problem that uses seed...

  3. Fast online determination of surfactant inhibition in acidic phase bioreactors.

    Science.gov (United States)

    Feitkenhauer, H

    2004-01-01

    Surfactants have been shown to inhibit the anaerobic digestion process severely, with the methanogenic microorganisms being the most affected. The diverse nature of surfactants used even in one (e.g. textile finishing) plant makes an online determination of surfactants sometimes very difficult and expensive. Therefore a fast online determination of inhibitory effects on the acidogenic microorganisms (first step of the degradation cascade) can help to give an early warning signal or to calculate a "pseudo"-surfactant concentration. In a two-phase system this information can be used to protect the methanogenic reactor against surfactant overloading and its long term negative effects. In this paper it is shown that the inhibition is a consequence of microbial inhibition and is not caused by an inactivation of extracellular hydrolytic enzymes (released by the cells for biopolymer cleavage). A titration technique was successfully employed to measure the surfactant inhibition in a laboratory-scale acidification reactor. Additional experiments demonstrate (using sodium dodecyl sulfate as the model substance) how inhibitory effects (and strategies to overcome inhibitory effects) can be investigated efficiently. PMID:14979534

  4. Screening of non-Ionic Surfactant for Enhancing Biobutanol Production.

    Science.gov (United States)

    Dhamole, Pradip B; Mane, Ravindra G; Feng, Hao

    2015-11-01

    This work deals with finding a suitable non-ionic surfactant which has high butanol capturing capacity and can be separated at a temperature close to room temperature and does not extract any intermediates or substrate (i.e., glucose). Importantly, it should be biocompatible, and its separation from the aqueous phase is not affected by other fermentation products. Hence, a pool of non-ionic Pluronic surfactants (L31, L61, L62D, L62LF, L62, L81, L92, L101, L121, L64, P65, P84, P104, P105) were selected for the study. Screening of the surfactant was done based on its hydrophile-lipophile balance (HLB) value, butanol capturing capacity (BCC), and cloud point temperature. Among the various surfactant investigated, L62D captured maximum amount of butanol (0.68 g/g of surfactant). Also, the cloud point temperature of L62D is close to room temperature (28.7 °C). Biocompatibility studies were carried out by conducting fermentation in presence of 3% L62D which resulted in 148% increase in butanol production as compared to control (without surfactant). Further, the fermentation products did not have strong influence on phase separation. PMID:26315133

  5. Comparative study on coating CdSe nanocrystals with surfactants

    International Nuclear Information System (INIS)

    We have synthesized CdSe nanocrystals (NCs) in sizes from 2.2 to 5.1 nm passivated with hydrophobic trioctylphosphine oxide (TOPO) in combination trioctylphosphine (TOP) or tributylphosphine (TBP) to obtain particles of the type CdSe/TOPO/TOP or CdSe/TOPO/TBP. These NCs were then dispersed in aqueous solution of ionic or non-ionic surfactants (such as stearate, oleic acid, Tween) using a biphase (water and chloroform or hexane) transfer method. It is found that both the structure of the surfactant and the native surface of the ligand govern the coating of the NCs with surfactants. More specifically, the hydrophobicity-hydrophilicity balance of the surfactant regulates the coating efficacy, thereby transferring the NC from the organic to the aqueous phase. The type of ligand on the NCs and the kind of coating surfactant also affect photoluminescence (PL). The ratio of PL and absorbance unit (defined as PL per 0.1 AU) was implemented as a tool to monitor changes in PL intensity and wavelength as a function of size, coatings and surface defects. Finally, the distribution of CdSe nanocrystals between pseudophases in cloud point extraction was discussed based on experimental results. It was concluded that the size of CdSe nanocrystal present in an appropriate pseudophase is correlated with the way in which the non-ionic surfactant coats CdSe nanocrystals. (author)

  6. Critical Heat Flux during Flow Boiling Experiment with Surfactant Solutions

    International Nuclear Information System (INIS)

    Some additives enhance heat transfer, although, the magnitude and mechanism of enhancement are not consistent or clearly understood. A low concentration of surfactant can also reduce the solution's surface tension considerably, and its level of reduction depends on the amount and type of surfactant present in solution. The surfactant concentrations are usually low enough that the addition of surfactant to water causes no significant change in saturation temperature and most other physical properties, except viscosity and surface tension. Reduced surface tension influences the activation of nucleation sites, bubble growth and dynamics, affecting the boiling heat transfer coefficient. Surfactants effect on CHF (Critical Heat Flux) was determined during flow boiling at atmospheric pressure in closed loop filled with water solutions of tri-sodium phosphate (TSP, Na3PO4.12H2O). TSP was added to the containment sump water to adjust pH level during accidents in nuclear power plants. CHF was measured for four water surfactant solutions at different mass fluxes (100 - 500 kg/m2sec) and two inlet subcooling temperatures (50 .deg. C and 75 .deg. C). Wettability was determined by measuring the contact angle at different concentration cases that will substantiate any CHF increase

  7. Growth kinetics of sulfur nanoparticles in aqueous surfactant solutions.

    Science.gov (United States)

    Chaudhuri, Rajib Ghosh; Paria, Santanu

    2011-02-15

    Sulfur is an important element has many practical applications when present as nanoparticles. Despite the practicable applications, limited studies are available in the literature related to synthesis of sulfur nanoparticles. Growth kinetics of colloidal sulfur particles synthesized from aqueous solutions using different surfactants have been studied here. The effects of different parameters such as reactant concentration, temperature, sonication, types of acids, types of surfactants, and even surfactant concentration are studied on the growth kinetics. Since the reaction rate is fast, particle growth depends on the parameters which affect diffusion of sulfur molecules. There is a linear relationship found among the reactant concentration and the particle coarsening rate constant. The growth kinetics was studied in the presence of different surfactants such as nonionic (poly(oxyethylene) p-tert-octylphenyl ether, TX-100), anionic (sodium dodecylbenzene sulfonate, SDBS), cationic (cetyltrimethyammonium bromide, CTAB) and results show the coarsening constant changes according to the following order: water>TX-100>SDBS>CTAB. The particle growth rate also depends on the surfactant concentration, coarsening rate constant decreases with the increase in surfactant concentration and become constant close to the critical micellar concentration (CMC). The coarsening rate constant also highly depends on the types of acid used as catalyst. PMID:21147482

  8. Field inversion gel electrophoresis in denaturing polyacrylamide gels.

    OpenAIRE

    Heller, C.; Beck, S

    1992-01-01

    The velocities of single stranded DNA molecules in denaturing polyacrylamide gels during symmetric and asymmetric field inversion were measured at different pulse times and gel concentrations. Under the conditions chosen in our study, pulse times as short as a few milliseconds lead to a retardation of DNA molecules larger than 400 bases. We found that a field inversion with an electric field in the forward direction of about double the strength of that applied in the backward direction is a g...

  9. Numerical study on a disordered model for DNA denaturation transition

    OpenAIRE

    Coluzzi, Barbara

    2005-01-01

    We study numerically a disordered version of the model for DNA denaturation transition (DSAW-DNA) consisting of two interacting SAWs in 3d, which undergoes a first order transition in the homogeneous case. The two possible values eAT and eGC of the interactions between base pairs are taken as quenched random variables distributed with equal probability along the chain. We measure quantities averaged over disorder such as the energy density, the specific heat and the probability distribution o...

  10. Determination of native and denatured BSA by chronopotentiometric peak H

    Czech Academy of Sciences Publication Activity Database

    Ostatná, Veronika; Paleček, Emil

    Balatonfured, 2007. s. 90. [Regional Biophysics Conference 2007. 21.08.2007-25.08.2007, Balatonfured] R&D Projects: GA ČR(CZ) GA301/07/0490; GA ČR(CZ) GP202/07/P497; GA MŠk(CZ) LC06035 Institutional research plan: CEZ:AV0Z50040507; CEZ:AV0Z50040702 Keywords : native and denatured BSA * guanidium chloride * constant current chronopotentiometry Subject RIV: BO - Biophysics

  11. Statistical Analyses of Complex Denaturing Gradient Gel Electrophoresis Profiles

    OpenAIRE

    Gafan, Gavin P.; Lucas, Victoria S.; Roberts, Graham J.; Petrie, Aviva; Wilson, Michael; David A. Spratt

    2005-01-01

    Studies using molecular techniques have demonstrated that a culture-based approach can severely underestimate the bacterial diversity in most environments. One of the molecular techniques that has been applied in microbial ecology is denaturing gradient gel electrophoresis (DGGE). The purpose of this study was to investigate differences in the microbiota of plaque, using a number of analysis techniques, from children without gingivitis (n = 30) and from those with gingivitis (n = 30). Extract...

  12. Statistical analyses of complex denaturing gradient gel electrophoresis profiles

    OpenAIRE

    Gafan, G. P.; Lucas, V S; Roberts, G J; Petrie, A; Wilson, M; Spratt, D. A.

    2005-01-01

    Studies using molecular techniques have demonstrated that a culture-based approach can severely underestimate the bacterial diversity in most environments. One of the molecular techniques that has been applied in microbial ecology is denaturing gradient gel electrophoresis (DGGE). The purpose of this study was to investigate differences in the microbiota of plaque, using a number of analysis techniques, from children without gingivitis (n = 30) and from those with gingivitis (n = 30). Extract...

  13. Contribution of water to pressure and cold denaturation of proteins

    OpenAIRE

    Bianco, Valentino; Franzese, Giancarlo

    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 i...

  14. Whey protein mouth drying influenced by thermal denaturation

    OpenAIRE

    Bull, Stephanie P.; Hong, Yuchun; Khutoryanskiy, Vitaliy V.; Parker, Jane K.; Faka, Marianthi; Methven, Lisa

    2016-01-01

    Whey proteins are becoming an increasingly popular functional food ingredient. There are, however, sensory properties associated with whey protein beverages that may hinder the consumption of quantities sufficient to gain the desired nutritional benefits. One such property is mouth drying. The influence of protein structure on the mouthfeel properties of milk proteins has been previously reported. This paper investigates the effect of thermal denaturation of whey proteins on physicochemical p...

  15. Finite size effects on thermal denaturation of globular proteins

    OpenAIRE

    Li, Mai Suan; Klimov, D. K.; Thirumalai, D.

    2004-01-01

    Finite size effects on the cooperative thermal denaturation of proteins are considered. A dimensionless measure of cooperativity, Omega, scales as N^zeta, where N is the number of amino acids. Surprisingly, we find that zeta is universal with zeta = 1 + gamma, where the exponent gamma characterizes the divergence of the susceptibility for a self-avoiding walk. Our lattice model simulations and experimental data are consistent with the theory. Our finding rationalizes the marginal stability of...

  16. Denaturation of whey proteins of milk during ohmic heating

    OpenAIRE

    Pereira, Ricardo; Teixeira, J. A.; Vicente, A.A.

    2010-01-01

    Ohmic heating has often been said to improve the sensorial quality of foodstuffs, which has been ttributed mainly to its volumetric heating mechanism and (eventually) to the presence of an electric field. This is still subject to doubts and questions from the scientific community, and it is therefore important to determine the effect of ohmic heating on food constituents. We have investigated whether ohmic heating technology would give rise to changes on the denaturation of whey proteins from...

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

    OpenAIRE

    Bianco, Valentino; Franzese, Giancarlo

    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 i...

  18. Dissecting the Pretransitional Conformational Changes in Aminoacylase I Thermal Denaturation

    OpenAIRE

    Su, Jing-Tan; Kim, Sung-hye; Yan, Yong-Bin

    2006-01-01

    Aminoacylase I (ACYI) catalyzes the stereospecific hydrolysis of L-acylamino acids and is generally assumed to be involved in the final step of the degradation of intracellular N-acetylated proteins. Apart from its crucial functions in intracellular amino acid metabolism, ACYI also has substantial commercial importance for the optical resolution of N-acylated DL-amino acids. As a zinc-dependent enzyme, ACYI is quite stable against heat-induced denaturation and can be regarded as a thermostabl...

  19. Surfactant induced autophobing.

    Science.gov (United States)

    Bera, B; Duits, M H G; Cohen Stuart, M A; van den Ende, D; Mugele, F

    2016-05-18

    Surfactant adsorption in a three-phase system and its influence on wetting properties are relevant in various applications. Here, we report a hitherto not observed phenomenon, namely the retraction of an aqueous drop on hydrophilic solid substrates (which we refer to as 'autophobing') in ambient oil containing water-insoluble fatty acids, caused by the deposition of these fatty acids from the ambient oil onto the solid substrate. AFM measurements confirm that the surfactant is deposited on the solid by the moving contact line. This leads to a more hydrophobic substrate, the retraction of the contact line and a concomitant increase in the contact angle. The deposition process is enabled by the formation of a reaction product between deprotonated fatty acids and Ca(2+) ions at the oil/water interface. We investigate how the transition to a new equilibrium depends on the concentrations of the fatty acids, the aqueous solute, the chain lengths of the fatty acid, and the types of alkane solvent and silica or mica substrates. This phenomenon is observed on both substrates and for all explored combinations of fatty acids and solvents and thus appears to be generic. In order to capture the evolution of the contact angle, we develop a theoretical model in which the rate of adsorption at the oil-water interface governs the overall kinetics of autophobing, and transfer to the solid is determined by a mass flux balance (similar to a Langmuir Blodgett transfer). PMID:27102975

  20. Preparation of denatured protein bone sterilized with gamma radiation

    International Nuclear Information System (INIS)

    The bone is one of the tissues more transplanted in the entire world by that the bone necessity for transplant every day becomes bigger. In the Bank of tissues Radio sterilized of the ININ the amnion and the pig skin are routinely processed. The tissue with which will be continued is with bone. Due to that in our country it doesn't have enough bone of human origin for the necessities required in the bone transplant, an option is the bone of bovine. Of this bone one can obtain denatured protein bone, with the same characteristics of the denatured protein human bone, the one which has been proven that it has good acceptance and incorporation in the human body when is transplanted. The method for the obtaining of the denatured protein bone of bovine, with the confirmation of the final product by means of X-ray diffraction is described. The radiosterilization of this bone with gamma rays and the determination of the lead content. (Author)

  1. Dimensions, energetics, and denaturant effects of the protein unstructured state.

    Science.gov (United States)

    Li, Maodong; Liu, Zhirong

    2016-03-01

    Determining the energetics of the unfolded state of a protein is essential for understanding the folding mechanics of ordered proteins and the structure-function relation of intrinsically disordered proteins. Here, we adopt a coil-globule transition theory to develop a general scheme to extract interaction and free energy information from single-molecule fluorescence resonance energy transfer spectroscopy. By combining protein stability data, we have determined the free energy difference between the native state and the maximally collapsed denatured state in a number of systems, providing insight on the specific/nonspecific interactions in protein folding. Both the transfer and binding models of the denaturant effects are demonstrated to account for the revealed linear dependence of inter-residue interactions on the denaturant concentration, and are thus compatible under the coil-globule transition theory to further determine the dimension and free energy of the conformational ensemble of the unfolded state. The scaling behaviors and the effective θ-state are also discussed. PMID:26683260

  2. [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. PMID:999984

  3. Serum albumin ligand binding volumes using high pressure denaturation

    International Nuclear Information System (INIS)

    Highlights: ► We use pressure shift assay to study the thermodynamics of decanoate and dodecanoate ligand binding to human serum albumin. ► Pressure shift assay provides information on ligand binding volumes. ► The ligands stabilized human serum albumin against both pressure and temperature denaturation. ► ANS is a strong human serum albumin stabilizer and competes with lipids for the same binding sites. - Abstract: The pressure shift assay (PSA, also termed either PressureFluor or differential pressure fluorimetry) was used to study the thermodynamics of decanoate and dodecanoate lipid binding to human serum albumin (HSA) in the temperature range from 25 °C to 80 °C and the pressure range from 0.1 MPa to 400 MPa. The ligands stabilized HSA against both pressure and temperature denaturation. The P–T phase diagram for HSA bound to saturated fatty acids is shown. Pressure induced HSA denaturation reversibility is demonstrated via either intrinsic tryptophan or extrinsic probe 1,8-anilinonaphthalene sulfonate (ANS) fluorescence. The effect of guanidinium in a PSA was studied. PSA provides information on ligand binding volumes. The volume changes from protein–ligand binding are thermodynamically important and could be used in designing compounds with specific volumetric binding properties.

  4. Mechanisms of enhanced mobilisation of trace metals by anionic surfactants in soil

    International Nuclear Information System (INIS)

    Long-term applications of small concentrations of surfactants in soil via wastewater irrigation or pesticide application may enhance trace metal solubility. Mechanisms by which anionic surfactants (Aerosol 22, SDS and Biopower) affect trace metal solubility were assessed using batch, incubation and column experiments. In batch experiments on seven soils, the concentrations of Cu, Cd, Ni and Zn in the dissolved fraction of soils increased up to 100-fold at the high application rates, but increased less than 1.5-fold below the critical micelle concentration. Dissolved metal concentrations were less than 20% affected by surfactants in long-term incubations (70 days) up to the largest dose of 200 mg C kg-1 soil. Leaching soil columns with A22 (100-1000 mg C L-1) under unsaturated conditions increased trace metal concentrations in the leachates 2-4 fold over the control. Correlation analysis and speciation modelling showed that the increased solubility of metals upon surfactant application was more related to the solubilisation of soil organic matter from soil than to complexation of the metals with the surfactant. Organic matter from soil was solubilised in response to a decrease of solution Ca2+ as a result of Ca-surfactant precipitation. At environmentally relevant concentrations, surfactant application is unlikely to have a significant effect on trace metal mobility. - Graphical abstract: Display Omitted Research highlights: →Anionic surfactants increase metal mobility by solubilising soil organic matter. → Metal complexation with surfactants is relevant only at elevated surfactant doses. → Surfactants have little effect on metal mobility at environmentally relevant doses. - Anionic surfactants mobilise metals from soil through solubilisation of soil organic matter and direct complexation.

  5. Mutations of the Gs α-subunit gene in Albright hereditary osteodystrophy detected by denaturing gradient gel electrophoresis

    International Nuclear Information System (INIS)

    Affected members of most kindreds with Albright hereditary osteodystrophy have a partial deficiency of functional Gs, the guanine nucleotide-binding protein that stimulates adenylyl cyclase. By use of the polymerase chain reaction to amplify genomic fragments with the attachment of a high-melting G+C-rich region (GC clamp) and analysis of these fragments by denaturing gradient gel electrophoresis, heterozygous mutations in the Gs α-subunit at the donor splice junction of intron 10 and a coding frameshift created by a single base deletion within exon 10. The findings illustrate the heterogeneity of genetic defects in Albright hereditary osteodystrophy and the usefulness of the polymerase chain reaction-denaturing gradient gel electrophoresis method to search rapidly for mutations in a large candidate gene

  6. MICROBIAL SURFACTANTS IN ENVIRONMENTAL TECHNOLOGIES

    Directory of Open Access Journals (Sweden)

    T. P. Pirog

    2015-08-01

    Full Text Available It was shown literature and own experimental data concerning the use of microbial surface active glycolipids (rhamno-, sophoro- and trehalose lipids and lipopeptides for water and soil purification from oil and other hydrocarbons, removing toxic heavy metals (Cu2+, Cd2+, Ni2+, Pb2+, degradation of complex pollution (oil and other hydrocarbons with heavy metals, and the role of microbial surfactants in phytoremediation processes. The factors that limit the use of microbial surfactants in environmental technologies are discussed. Thus, at certain concentrations biosurfactant can exhibit antimicrobial properties and inhibit microorganisms destructing xenobiotics. Microbial biodegradability of surfactants may also reduce the effectiveness of bioremediation. Development of effective technologies using microbial surfactants should include the following steps: monitoring of contaminated sites to determine the nature of pollution and analysis of the autochthonous microbiota; determining the mode of surfactant introduction (exogenous addition of stimulation of surfactant synthesis by autochthonous microbiota; establishing an optimal concentration of surfactant to prevent exhibition of antimicrobial properties and rapid biodegradation; research both in laboratory and field conditions.

  7. Genetic disorders of surfactant homeostasis.

    Science.gov (United States)

    Whitsett, Jeffrey A; Wert, Susan E; Xu, Yan

    2005-01-01

    Adaptation to air breathing at birth requires the precise orchestration of cellular processes to initiate fluid clearance, enhance pulmonary blood flow, and to synthesize and secrete pulmonary surfactant needed to reduce surface tension at the air-liquid interface in the alveoli. Genetic programs regulating the synthesis of the surfactant proteins and lipids required for the production and function of pulmonary surfactant are highly conserved across vertebrates, and include proteins that regulate the synthesis and packaging of pulmonary surfactant proteins and lipids. Surfactant proteins B and C (SP-B and -C) are small, uniquely hydrophobic proteins that play important roles in the stability and spreading of surfactant lipids in the alveolus. Deletion or mutations in SP-B and -C cause acute and chronic lung disease in neonates and infants. SP-B and -C are synthesized and packaged with surfactant phospholipids in lamellar bodies. Normal lamellar body formation requires SP-B and a member of the ATP-binding cassette (ABC) family of ATP-dependent membrane-associated transport proteins, ABCA3. Mutations in ABCA3 cause fatal respiratory disease in newborns and severe chronic lung disease in infancy. Expression of SP-B, -C, and ABCA3 are coregulated during late gestation by transcriptional programs influenced by thyroid transcription factor-1 and forkhead box a2, transcription factors that regulate both differentiation of the respiratory epithelium and transcription of genes required for perinatal adaptation to air breathing. PMID:15985750

  8. The role of surfactant in asthma

    Directory of Open Access Journals (Sweden)

    Hohlfeld Jens

    2002-01-01

    Full Text Available Abstract Pulmonary surfactant is a unique mixture of lipids and surfactant-specific proteins that covers the entire alveolar surface of the lungs. Surfactant is not restricted to the alveolar compartment; it also reaches terminal conducting airways and is present in upper airway secretions. While the role of surfactant in the alveolar compartment has been intensively elucidated both in health and disease states, the possible role of surfactant in the airways requires further research. This review summarizes the current knowledge on surfactant functions regarding the airway compartment and highlights the impact of various surfactant components on allergic inflammation in asthma.

  9. Transient exposure of pulmonary surfactant to hyaluronan promotes structural and compositional transformations into a highly active state.

    Science.gov (United States)

    Lopez-Rodriguez, Elena; Cruz, Antonio; Richter, Ralf P; Taeusch, H William; Pérez-Gil, Jesús

    2013-10-11

    Pulmonary surfactant is a lipid-protein complex that lowers surface tension at the respiratory air-liquid interface, stabilizing the lungs against physical forces tending to collapse alveoli. Dysfunction of surfactant is associated with respiratory pathologies such as acute respiratory distress syndrome or meconium aspiration syndrome where naturally occurring surfactant-inhibitory agents such as serum, meconium, or cholesterol reach the lung. We analyzed the effect of hyaluronan (HA) on the structure and surface behavior of pulmonary surfactant to understand the mechanism for HA-promoted surfactant protection in the presence of inhibitory agents. In particular, we found that HA affects structural properties such as the aggregation state of surfactant membranes and the size, distribution, and order/packing of phase-segregated lipid domains. These effects do not require a direct interaction between surfactant complexes and HA and are accompanied by a compositional reorganization of large surfactant complexes that become enriched with saturated phospholipid species. HA-exposed surfactant reaches very high efficiency in terms of rapid and spontaneous adsorption of surfactant phospholipids at the air-liquid interface and shows significantly improved resistance to inactivation by serum or cholesterol. We propose that physical effects pertaining to the formation of a meshwork of interpenetrating HA polymer chains are responsible for the changes in surfactant structure and composition that enhance surfactant function and, thus, resistance to inactivation. The higher resistance of HA-exposed surfactant to inactivation persists even after removal of the polymer, suggesting that transient exposure of surfactant to polymers like HA could be a promising strategy for the production of more efficient therapeutic surfactant preparations. PMID:23983120

  10. Nanoscopic surfactant behavior of the porin MspA in aqueous media

    Directory of Open Access Journals (Sweden)

    Ayomi S. Perera

    2013-04-01

    Full Text Available The mycobacterial porin MspA is one of the most stable channel proteins known to date. MspA forms vesicles at low concentrations in aqueous buffers. Evidence from dynamic light scattering, transmission electron microscopy and zeta-potential measurements by electrophoretic light scattering indicate that MspA behaves like a nanoscale surfactant. The extreme thermostability of MspA allows these investigations to be carried out at temperatures as high as 343 K, at which most other proteins would quickly denature. The principles of vesicle formation of MspA as a function of temperature and the underlying thermodynamic factors are discussed here. The results obtained provide crucial evidence in support of the hypothesis that, during vesicle formation, nanoscopic surfactant molecules, such as MspA, deviate from the principles underlined in classical surface chemistry.

  11. Nanoscopic surfactant behavior of the porin MspA in aqueous media.

    Science.gov (United States)

    Perera, Ayomi S; Wang, Hongwang; Shrestha, Tej B; Troyer, Deryl L; Bossmann, Stefan H

    2013-01-01

    The mycobacterial porin MspA is one of the most stable channel proteins known to date. MspA forms vesicles at low concentrations in aqueous buffers. Evidence from dynamic light scattering, transmission electron microscopy and zeta-potential measurements by electrophoretic light scattering indicate that MspA behaves like a nanoscale surfactant. The extreme thermostability of MspA allows these investigations to be carried out at temperatures as high as 343 K, at which most other proteins would quickly denature. The principles of vesicle formation of MspA as a function of temperature and the underlying thermodynamic factors are discussed here. The results obtained provide crucial evidence in support of the hypothesis that, during vesicle formation, nanoscopic surfactant molecules, such as MspA, deviate from the principles underlined in classical surface chemistry. PMID:23766950

  12. 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

  13. Treatment with exogenous surfactant stimulates endogenous surfactant synthesis in premature infants with respiratory distress syndrome

    NARCIS (Netherlands)

    Bunt, JEH; Carnielli, VP; Janssen, DJ; Wattimena, JLD; Hop, WC; Sauer, PJ; Zimmermann, LJI

    2000-01-01

    Objective: Treatment of preterm infants with respiratory distress syndrome (RDS) with exogenous surfactant has greatly improved clinical outcome. Some infants require multiple doses, and it has not been studied whether these large amounts of exogenous surfactant disturb endogenous surfactant metabol

  14. 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.

  15. Thermal denaturation and regeneration of japanese-radish peroxidase.

    Science.gov (United States)

    Tamura, Y; Morita, Y

    1975-09-01

    Thermal denaturation of Japanese-radish peroxidase [EC 1.11.1.7] was investigated with respect to its spectrophotometric properties and effect on the enzymatic activity. Inactivation of the peroxidase occurred at temperatures higher than 60degrees and involved three processes, i.e., dissociation of protohemin from the holoperoxidase, a conformation change in the apperoxidase, and the modification or degradation of protohemin. The splitting process of protohemin from holoperoxidase as followed by the change in the absorption spectrum at high temperatures coincided with the degrease in the activity, and it was found to be at least biphasic. The regeneration of peroxidase on cooling to room temperature was essentially reversible at neutral pH, while at pH 5 and pH 9 these processes were irreversible. The irreversibility at acidic pH was mainly due to an irreversible change in the conformation of the apoenzyme. The difference spectrum of heat-treated apoperoxidase exhibited a denaturation blueshift with negative maxima at 287 and 294 nm, and the total protein fluorescence quantum yield. qprotein, increased by 20% compared to that of the untreated apoenzyme. On the other hand, the irreversibility at alkaline pH was largely attributable to the modification of protohemin. Apoperoxidase was more resistnat to heat denaturation but the modification or degradation of protohemin in heated enzyme was greater at alkaline pH than at acidic pH. The pyridine-ferrohemochrome spectrum of peroxidase exhibited slight shifts of the maxima of the alpha-band to shorter wavelength on heat treatment, and the paper chromatogram showed the presence of a new derivative other than protohemin. The modified product is probably (2(4)-vinyl-4(2)-hydroxyethyldeuterohemin. PMID:5412

  16. Membrane bridging and hemifusion by denaturated Munc18.

    Directory of Open Access Journals (Sweden)

    Yi Xu

    Full Text Available Neuronal Munc18-1 and members of the Sec1/Munc18 (SM protein family play a critical function(s in intracellular membrane fusion together with SNARE proteins, but the mechanism of action of SM proteins remains highly enigmatic. During experiments designed to address this question employing a 7-nitrobenz-2-oxa-1,3-diazole (NBD fluorescence de-quenching assay that is widely used to study lipid mixing between reconstituted proteoliposomes, we observed that Munc18-1 from squid (sMunc18-1 was able to increase the apparent NBD fluorescence emission intensity even in the absence of SNARE proteins. Fluorescence emission scans and dynamic light scattering experiments show that this phenomenon arises at least in part from increased light scattering due to sMunc18-1-induced liposome clustering. Nuclear magnetic resonance and circular dichroism data suggest that, although native sMunc18-1 does not bind significantly to lipids, sMunc18-1 denaturation at 37 °C leads to insertion into membranes. The liposome clustering activity of sMunc18-1 can thus be attributed to its ability to bridge two membranes upon (perhaps partial denaturation; correspondingly, this activity is hindered by addition of glycerol. Cryo-electron microscopy shows that liposome clusters induced by sMunc18-1 include extended interfaces where the bilayers of two liposomes come into very close proximity, and clear hemifusion diaphragms. Although the physiological relevance of our results is uncertain, they emphasize the necessity of complementing fluorescence de-quenching assays with alternative experiments in studies of membrane fusion, as well as the importance of considering the potential effects of protein denaturation. In addition, our data suggest a novel mechanism of membrane hemifusion induced by amphipathic macromolecules that does not involve formation of a stalk intermediate.

  17. Protein recovery from surfactant precipitation.

    Science.gov (United States)

    Cheng, Shu Ian; Stuckey, David C

    2011-01-01

    The recovery of lysozyme from an aqueous solution containing precipitated lysozyme-AOT complexes formed by the direct addition of sodium bis-(2-ethylhexyl) sulfosuccinate (AOT) to a lysozyme solution was studied using both solvents, and a counterionic surfactant. Ethanol,methanol and solvent mixtures dissolved the surfactant precipitate and recovered lysozyme as a solid. Recovery efficiency and protein stability varied with the type of solvent used. An entirely different method of recovery was also evaluated using a counterionic surfactant: tri-octylmethylammonium chloride (TOMAC) which bound to AOT releasing lysozyme into solution.Complete recovery (100%) of lysozyme was achieved at a molar ratio of 2:1(TOMAC:AOT), and the original protein activity was maintained in the final aqueous phase.The recovered lysozyme retained its secondary structure as observed in circular dichroism(CD) spectra. Specific activity studies show that counterionic surfactant extraction does not alter the biological activity of the enzyme. PMID:22235487

  18. Electrochemical Oscillations Induced by Surfactants

    Institute of Scientific and Technical Information of China (English)

    翟俊红; 贺占博

    2003-01-01

    A new type of electrochemical oscillation induced by surfactant was observed in experiments. The electrochemical system is a Daniell cell with a copper rod in CuSO4 aqueous and an aluminum rod in Al(NO3)3 aqueous as electrodes. The surfactants are CTAB, TX-100, SLS. The addition of trace surfactant solution by a micro-syringe made the original monotonously changing electrochemical system produce obvious periodic phenomena. At the mean time, the copper ion selective electrode and Hg2SO4 reference electrode were used to monitor the copper electrode reaction and determine its rate constant k of first order reaction. According to the experimental results of electrode reaction kinetics, the possible mechanism was found to be the polarization induced from the directional adsorption of trace surfactant on the electrode surface. That is the electrochemical oscillations.

  19. Biodegradation of surfactant bearing wastes

    International Nuclear Information System (INIS)

    In nuclear industry, during decontamination of protective wears and contaminated materials, detergents are employed to bring down the level of radioactive contamination within safe limits. However, the surfactant present in these wastes interferes in the chemical treatment process, reducing the decontamination factor. Biodegradation is an efficient and ecologically safe method for surfactant removal. A surfactant degrading culture was isolated and inoculated separately into simulated effluents containing 1% yeast extract and 5-100 ppm sodium lauryl sulphate (SLS) and 1% yeast extract and 5-100 ppm of commercial detergent respectively. The growth of the bacterial culture and the degradation characteristics of the surfactant in the above effluents were monitored under both dynamic and static conditions. (author). 6 refs., 6 figs., 1 tab

  20. Rheological response of methylcellulose toward alkanediyl-α,ω-bis(dimethylcetylammonium bromide) surfactants with varying spacer length.

    Science.gov (United States)

    Shah, Rais Ahmad; Chat, Oyais Ahmad; Maswal, Masrat; Rather, Ghulam Mohammad; Dar, Aijaz Ahmad

    2016-06-25

    The modulation of properties of methylcellulose (MC) by cationic gemini surfactants with varying spacer lengths was studied employing tensiometry, rheometry and turbidimetry. Surface tension measurements anticipate that the gemini surfactant with longer spacer chain length saturates MC at lower concentrations owing to its greater hydrophobicity compared to shorter spacer analogues. Rheometric and turbidimetric measurements suggest that at very low concentrations of gemini surfactants, ion-dipole type of interactions between MC and gemini surfactants promote the extension of polymer chains which is manifested by an initial increase in the low shear viscosity and gelation temperature of MC-gemini surfactant systems, and lowering of turbidity. Such interactions were found to be stronger in case of 16-4-16 than 16-5-16, and almost absent in case of 16-6-16 surfactant system. However at concentrations above CAC, hydrophobic forces operative between MC and gemini surfactants were found to be more for 16-6-16 than that of 16-5-16 and 16-4-16. The final levelling of MC viscosity in presence of all the three gemini surfactants and the variation of gelation temperature suggests the solubilization of network junctions in the surfactant micelles. Moreover, the presence of gemini surfactant strongly affects the interaction of MC with a model hydrophobic drug rifampicin.The results highlight the importance of gemini surfactants and their spacer length in controlling the structural dynamics of MC and its effective use in pharmaceutical and food industry. PMID:27083805

  1. Determination of native and denatured BSA by chronopotentiometric peak H

    Czech Academy of Sciences Publication Activity Database

    Bartošík, Martin; Ostatná, Veronika; Paleček, Emil

    Brno, 2008. s. 12-13. ISBN 978-80-210-4525-5. [Pracovní setkání fyzikálních chemiků a elektrochemiků /8./. 04.02.2008-05.02.2008, Brno] R&D Projects: GA ČR(CZ) GP202/07/P497; GA MŠk(CZ) LC06035 Institutional research plan: CEZ:AV0Z50040507; CEZ:AV0Z50040702 Keywords : denaturation * BSA * peak H Subject RIV: BO - Biophysics

  2. Anatomy of energetic changes accompanying urea-induced protein denaturation

    OpenAIRE

    Auton, Matthew; Holthauzen, Luis Marcelo F.; Bolen, D. Wayne

    2007-01-01

    Because of its protein-denaturing ability, urea has played a pivotal role in the experimental and conceptual understanding of protein folding and unfolding. The measure of urea's ability to force a protein to unfold is given by the m value, an experimental quantity giving the free energy change for unfolding per molar urea. With the aid of Tanford's transfer model [Tanford C (1964) J Am Chem Soc 86:2050–2059], we use newly obtained group transfer free energies (GTFEs) of protein side-chain an...

  3. Potential-dependent surface denaturation of BSA in acid media

    Czech Academy of Sciences Publication Activity Database

    Paleček, Emil; Ostatná, Veronika

    2009-01-01

    Roč. 134, č. 10 (2009), s. 2076-2080. ISSN 0003-2654 R&D Projects: GA ČR(CZ) GA301/07/0490; GA ČR(CZ) GP202/07/P497; GA AV ČR(CZ) KJB100040901; GA MŠk(CZ) LC06035 Institutional research plan: CEZ:AV0Z50040507; CEZ:AV0Z50040702 Keywords : bovine serum albumin denaturation * chronopotentiometry of BSA Subject RIV: BO - Biophysics Impact factor: 3.272, year: 2009

  4. Persurf, a New Method to Improve Surfactant Delivery: A Study in Surfactant Depleted Rats

    OpenAIRE

    Burkhardt, Wolfram; Kraft, Stephan; Ochs, Matthias; Proquitté, Hans; Mense, Lars; Rüdiger, Mario

    2012-01-01

    Purpose Exogenous surfactant is not very effective in adults with ARDS, since surfactant does not reach atelectatic alveoli. Perfluorocarbons (PFC) can recruit atelectatic areas but do not replace impaired endogenous surfactant. A surfactant-PFC-mixture could combine benefits of both therapies. The aim of the proof-of-principal-study was to produce a PFC-in-surfactant emulsion (Persurf) and to test in surfactant depleted Wistar rats whether Persurf achieves I.) a more homogenous pulmonary dis...

  5. Severe adverse effects related to dermal exposure to a glyphosate-surfactant herbicide

    DEFF Research Database (Denmark)

    Mariager, T P; Madsen, P V; Ebbehøj, N E;

    2013-01-01

    This is a case of severe chemical burns following prolonged accidental exposure to a glyphosate-surfactant herbicide. The patient developed local swelling, bullae and exuding wounds. Neurological impairment followed affecting finger flexion and sensation with reduced nerve conduction. Imaging...

  6. Surfactant damages on coastal vegetation in southern Italy

    Directory of Open Access Journals (Sweden)

    2005-01-01

    Full Text Available Coastal vegetation decline caused by seaspray has been reported to affect a variety of species in several countries: Australia, South of France, along the Italian Tyrrhenian coast, Spain and Tunisia. The most serious injury is due to the interaction between sea salt and surfactants, even if surfactants may cause direct damage on cell membranes. The salt uptake is enhanced by the durfactant-induced erosion of the epicuticular wax, which reduces the water surface tension. The symptoms are non-specific and consist in leaf discoloration and necrosis. In needles, necrosis begins from the apex; in leaves, from the edges. Directionality of crown damage is the main symptom for diagnosing the involvement of polluted seaspray. If an obstacle is placed between trees and sea wind, the trees do not show appreciable damage. In Italy, the tree decline caused by seaspray and surfactants has been investigated with special reference to the pinewoods of the San Rossore (Tuscany, Central Italy, or on the Tyrrhenian coastlands of Central Italy, such as the area around Castelporziano in Lazio. This research is aimed at a preliminary assessment of the extent of surfactant damage to the coastal vegetation in four regions in Southern Italy by: i field surveys and mapping of damage caused by surfactants; ii detecting the presence of surfactants on the tree crowns. The damages have been observed in a lot of zones in Apulia, Basilicata, Campania and Calabria, within 500 m inland from the sea, for a maximum length of 5500 m coastline, near the mouth of a river or stream, near the outlet of sewage canals and in any other coastal areas where the surface currents carry a surfactant load.

  7. Comparison of in vitro predictive tests for irritation induced by anionic surfactants.

    Science.gov (United States)

    Goffin, V; Paye, M; Piérard, G E

    1995-07-01

    Skin compatibility of anionic surfactants may often but not always be predicted by in vitro tests. For instance, the correlation between in vivo and in vitro data is classically hampered in the presence of magnesium. This ion is known to interfere with in vitro skin irritation predictive tests based on protein denaturation. This study was conducted to compare a recently introduced assay, corneosurfametry, with other in vitro tests including the pH-rise of bovine serum albumin, collagen swelling, and zein solubilization tests. Corneosurfametry entails collection of cyanoacrylate skin surface strippings and short contact time with surfactants, followed by staining samples with toluidine blue and basic fuchsin dyes. Measurements are made by reflectance colorimetry. Data show that irritation potentials predicted by corneosurfametry agree with those obtained by established in vivo and in vitro irritation tests. Moreover, corneosurfametry data are not artificially lowered by addition of magnesium in surfactant solutions. In conclusion, corneosurfametry should be viewed as one of the realistic predictive tests for surfactant irritancy. PMID:7493460

  8. The Effect of Salinity on Surfactant Flooding: A Literature Review and an Experimental Study

    OpenAIRE

    Tverdal, Thomas Foldøy

    2013-01-01

    Surfactant flooding is a proven EOR technique, which mobilizes residual oil by reducing interfacial tension (IFT). Several parameters affect the phase behaviour of a microemulsion system and a successful surfactant flooding needs to be designed according to these parameters. Salinity is probably the main design parameter and has a substantial affect on phase behaviour. Injection of low salinity water is reported to mobilize additional oil both as a secondary waterflood and as a tertiary enhan...

  9. Improvement of lung mechanics by exogenous surfactant: effect of prior application of high positive end-expiratory pressure

    OpenAIRE

    Hartog, Anneke; Gommers, Diederik; Haitsma, J.J.; Lachmann, Burkhard

    2000-01-01

    textabstractThe use of a ventilation strategy with high positive end-expiratory pressure (PEEP) that is intended to recruit collapsed alveoli and to prevent recurrent collapse can reduce alveolar protein influx in experimental acute lung injury (ALI). This could affect the pulmonary response to treatment with surfactant, since plasma proteins inhibit surfactant function. We studied the effect of exogenous surfactant on lung mechanics after 4 h of mechanical ventilation with high or low PEEP. ...

  10. XAFS studies of Au nanocrystals passivated by different surfactants

    International Nuclear Information System (INIS)

    The electronic and atomic structures of Au nanocrystals affected by different surfactants (PPh3, PVP, and dodecanethiol) capping were studied by X-ray absorption fine structure (XAFS) at Au L3-edge. For PPh3, PVP, and dodecanethiol-capped Au nanocrystals, the surface Au atoms interact with P, O, and S atoms respectively; however, only for dodecanethiol-capped Au nanocrystals, a significant electron transfer between Au and S atoms is observed. The extend-XAFS results reveal that the atomic structure disorder of Au-Au shell gradually increases from 0.0095 to 0.0152 Å2 when the surfactants goes from PPh3 to dodecanethiol. These results suggest that the surfactants would change the electronic and atomic structures of Au nanocrystals rather than merely passivates on the surface of Au nanocrystals.

  11. U.S. leans toward denatured thorium cycle

    International Nuclear Information System (INIS)

    Denatured thorium appears to be the most promising among the nonproliferating alternatives to the plutonium cycle, which the Carter Administration is trying to cancel. Criteria for a better system include uranium utilization comparable to current light water reactors and minimal separation of fissile material into the waste stream. Comparisons with other systems conclude that thorium is preferable because it can lead to an acceptable fast breeder. The thorium cycle can be placed in energy centers for sensitive facilities and can also be introduced into ongoing light water systems. Reprocessing can be handled in the centers, where thorium can be mixed with plutonium for use in reactors within the center, while light water reactors operate on the outside. Any fuel leaving the center would be unsuitable for weapons. Later adaptation to in-center fast breeders will extend energy supplies, although a thorium breeder will be less efficient than a plutonium fast breeder. Denatured thorium is a technical answer to a complex political problem, but those in the nuclear industry see the U.S. goal of a nonproliferating fuel as futile in the light of world politics and breeder efforts in other countries

  12. Protein denaturation of banana prawns (Penaeus marquensis) after gamma irradiation

    International Nuclear Information System (INIS)

    The aim of this investigation was to determine the irradiation dose limit for maintaining shrimps freshness, based on the existence of protein denaturation of shrimps caused by gamma irradiation at radurization dose range. Protein denaturatio was studied using tryptic digestibility, solubility, and Ca ATPas actomyosin activity as the criterions. Electrophoretic studies were done to detect structural changes in protein that probably occured after irradiation at the applied doses. It was proved that tryptic digestibility, solubility, and Ca ATPase actomyosin activity of control and samples irradiated at 3, 4, and 5 kGy were significantly different (P<0.01) which indicated the existence of protein denaturation. Protein patterns of samples irradiated at 4 and 5 kGy were also distinctly different with those of the control. The 7th. band was broken into two bands. It could be concluded that for maintaining the freshness of shrimps, gamma irradiation dose used should not exceed 3 kGy. (authors). 8 refs, 1 fig 4 tabs

  13. 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.

  14. Thermal denaturation of sunflower globulins in low moisture conditions

    International Nuclear Information System (INIS)

    DSC analysis in pressure resisting pans of sunflower oil cake makes appear the endothermic peak of sunflower globulins denaturation. Its temperature decreases from 189.5 to 119.9 deg. C while the corresponding enthalpy increases from 2.6 to 3.3 J/g of sample, or from 6.7 to 12.2 J/g of dry protein, when the samples moisture content varies from 0 to 30.0% of the total weight. The plot of the denaturation temperature versus the moisture content is not linear but has a rounded global shape and seems to follow the hydration behavior of the proteins, modeled with the sorption isotherm. As it can be seen on scanning electron microscopy (SEM) micrographs, protein corpuscles 'melt' after such a thermal treatment and large aggregates form by coagulation. Moisture dependence of the 'fusion' temperature of native proteic organization, in low moisture conditions, offers so a new characterization method for the use of vegetable proteins in agro-materials

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

    OpenAIRE

    Pica, Andrea; Graziano, Giuseppe

    2015-01-01

    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...

  16. Irreversible Denaturation of Maltodextrin Glucosidase Studied by Differential Scanning Calorimetry, Circular Dichroism, and Turbidity Measurements

    OpenAIRE

    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 ...

  17. The pressure dependence of hydrophobic interactions is consistent with the observed pressure denaturation of proteins

    OpenAIRE

    Hummer, Gerhard; Garde, Shekhar; García, Angel E.; Paulaitis, Michael E.; Pratt, Lawrence R.

    1998-01-01

    Proteins can be denatured by pressures of a few hundred MPa. This finding apparently contradicts the most widely used model of protein stability, where the formation of a hydrophobic core drives protein folding. The pressure denaturation puzzle is resolved by focusing on the pressure-dependent transfer of water into the protein interior, in contrast to the transfer of nonpolar residues into water, the approach commonly taken in models of protein unfolding. Pressure denaturation of proteins ca...

  18. Secondary-Structure Analysis of Denatured Proteins by Vacuum-Ultraviolet Circular Dichroism Spectroscopy

    OpenAIRE

    Matsuo, Koichi; Sakurada, Yoshie; Yonehara, Ryuta; Kataoka, Mikio; Gekko, Kunihiko

    2007-01-01

    To elucidate the structure of denatured proteins, we measured the vacuum-ultraviolet circular dichroism (VUVCD) spectra from 260 to 172 nm of three proteins (metmyoglobin, staphylococcal nuclease, and thioredoxin) in the native and the acid-, cold-, and heat-denatured states, using a synchrotron-radiation VUVCD spectrophotometer. The circular dichroism spectra of proteins fully unfolded by guanidine hydrochloride (GdnHCl) were also measured down to 197 nm for comparison. These denatured prote...

  19. The effect of microwave thermal denaturation on release properties of bovine serum albumin and gluten matrices

    OpenAIRE

    Qasem, Rani J.

    2006-01-01

    The purpose of this study was to compare the effects of denaturation by microwave irradiation on release properties of 2 physically different proteins. Matrices were prepared from water-soluble bovine serum albumin loaded with metoclopramide and sorbed with adequate amount of moisture were thermally denatured in a microwave oven. The release profile of the rather insoluble denatured albumin matrices followed the classical Fickian diffusion profile. The release rate was dependent on the degree...

  20. Evaporation of Sessile Droplets Laden with Particles and Insoluble Surfactants.

    Science.gov (United States)

    Karapetsas, George; Chandra Sahu, Kirti; Matar, Omar K

    2016-07-12

    We consider the flow dynamics of a thin evaporating droplet in the presence of an insoluble surfactant and noninteracting particles in the bulk. On the basis of lubrication theory, we derive a set of evolution equations for the film height, the interfacial surfactant, and bulk particle concentrations, taking into account the dependence of liquid viscosity on the local particle concentration. An important ingredient of our model is that it takes into account the fact that the surfactant adsorbed at the interface hinders evaporation. We perform a parametric study to investigate how the presence of surfactants affects the evaporation process as well as the flow dynamics with and without the presence of particles in the bulk. Our numerical calculations show that the droplet lifetime is affected significantly by the balance between the ability of the surfactant to enhance spreading, suppressing the effect of thermal Marangoni stresses-induced motion, and to hinder the evaporation flux through the reduction of the effective interfacial area of evaporation, which tend to accelerate and decelerate the evaporation process, respectively. For particle-laden droplets and in the case of dilute solutions, the droplet lifetime is found to be weakly dependent on the initial particle concentration. We also show that the particle deposition patterns are influenced strongly by the direct effect of the surfactant on the evaporative flux; in certain cases, the "coffee-stain" effect is enhanced significantly. A discussion of the delicate interplay between the effects of capillary pressure and solutal and thermal Marangoni stresses, which drive the liquid flow inside of the evaporating droplet giving rise to the observed results, is provided herein. PMID:27300638

  1. The detection of surfactant proteins A, B, C and D in the human brain and their regulation in cerebral infarction, autoimmune conditions and infections of the CNS.

    Directory of Open Access Journals (Sweden)

    Stefan Schob

    Full Text Available Surfactant proteins (SP have been studied intensively in the respiratory system. Surfactant protein A and surfactant protein D are proteins belonging to the family of collectins each playing a major role in the innate immune system. The ability of surfactant protein A and surfactant protein D to bind various pathogens and facilitate their elimination has been described in a vast number of studies. Surfactant proteins are very important in modulating the host's inflammatory response and participate in the clearance of apoptotic cells. Surfactant protein B and surfactant protein C are proteins responsible for lowering the surface tension in the lungs. The aim of this study was an investigation of expression of surfactant proteins in the central nervous system to assess their specific distribution patterns. The second aim was to quantify surfactant proteins in cerebrospinal fluid of healthy subjects compared to patients suffering from different neuropathologies. The expression of mRNA for the surfactant proteins was analyzed with RT-PCR done with samples from different parts of the human brain. The production of the surfactant proteins in the brain was verified using immunohistochemistry and Western blot. The concentrations of the surfactant proteins in cerebrospinal fluid from healthy subjects and patients suffering from neuropathologic conditions were quantified using ELISA. Our results revealed that surfactant proteins are present in the central nervous system and that the concentrations of one or more surfactant proteins in healthy subjects differed significantly from those of patients affected by central autoimmune processes, CNS infections or cerebral infarction. Based on the localization of the surfactant proteins in the brain, their different levels in normal versus pathologic samples of cerebrospinal fluid and their well-known functions in the lungs, it appears that the surfactant proteins may play roles in host defense of the brain

  2. Surfactant flooding of diesel-contaminated soils

    International Nuclear Information System (INIS)

    At one installation, approximately 60,000 gallons of No. 2 diesel fuel leaked into the subsurface environment, with contamination at depths of 6 to 34 m below the surface. Argonne National Laboratory was contracted to perform treatability studies for site remediation. The treatability studies focused on four separate phases: (1) leachability studies on the various contaminated soil borings, (2) air stripping studies, (3) bioremediation studies, and (4) surfactant screening/surfactant flooding studies. This paper summarizes the fourth phase of this research program after initial surfactant screening of 21 surfactants. Three of the surfactants were used for the surfactant flooding studies; the results from that phase of the research program are described

  3. 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.)

  4. Visualization of Early Events in Acetic Acid Denaturation of HIV-1 Protease: A Molecular Dynamics Study

    OpenAIRE

    Borkar, Aditi Narendra; Rout, Manoj Kumar; Hosur, Ramakrishna V.

    2011-01-01

    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 re...

  5. 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.

  6. Cold denaturation and 2H2O stabilization of a staphylococcal nuclease mutant.

    OpenAIRE

    Antonino, L C; Kautz, R. A.; Nakano, T.; Fox, R. O.; Fink, A L

    1991-01-01

    Cold denaturation is now recognized as a general property of proteins but has been observed only under destabilizing conditions, such as moderate denaturant concentration or low pH. By destabilizing the protein using site-directed mutagenesis, we have observed cold denaturation at pH 7.0 in the absence of denaturants in a mutant of staphylococcal nuclease, which we call NCA S28G for a hybrid protein between staphylococcal nuclease and concanavalin A in which there is the point mutation Ser-28...

  7. Surfactant retention on Berea Sandstone: effects of phase behavior and temperature

    Energy Technology Data Exchange (ETDEWEB)

    Novosad, J.B; Baxter, L.; Parker, G.

    1981-08-01

    The total amount of surfactant retained in porous media is probably one of the most important parameters used in determining the economic success or failure of chemical flooding. It has been recoginzed in the literature that there are several physico-chemical processes that contribute to the overall retention of surfactants. Most experimental data are reported as total retention, and a distinction among the contributing mechanisms is not usually made. The report describes laboratory investigations of surfactant retention in Berea cores with the main emphasis on the experimental differentiation between surfactant losses due to adsorption and those due to trapping in the immobile hydrocarbon phase left in the core after surfactant flooding. Surfactants investigated include pure sulfonate, petroleum sulfonate, and synthetic sulfornate in systems forming lower and middle phase microemulsions. The temperature range studied was between 20 and 70/sup 0/C. Results indicate that losses of surfactant caused by trapping in the immobile oil phase can be substantial and, more importantly, that minor changes in experimental conditions, such as variations in surfactant slug size, affect the measured losses substantially. It is shown that similar experiments may yield very different results in terms of total retention and, if the effects of the different types of surfactant losses cannot be experimentally determined, erroneous conclusions may be reached. For example, this is illustrated in the case of the temperature dependence of total surfactant retention. The correct interpretation of the experimental data requires more information than the total surfactant retention value, as both phase behaviour and adsorption vary with temperature. 15 refs., 15 figs., 6 tabs.

  8. Interactions between Surfactants in Solution and Electrospun Protein Fibers: Effects on Release Behavior and Fiber Properties.

    Science.gov (United States)

    Stephansen, Karen; García-Díaz, María; Jessen, Flemming; Chronakis, Ioannis S; Nielsen, Hanne M

    2016-03-01

    Intermolecular interaction phenomena occurring between endogenous compounds, such as proteins and bile salts, and electrospun compounds are so far unreported, despite the exposure of fibers to such biorelevant compounds when applied for biomedical purposes, e.g., tissue engineering, wound healing, and drug delivery. In the present study, we present a systematic investigation of how surfactants and proteins, as physiologically relevant components, interact with insulin-loaded fish sarcoplasmic protein (FSP) electrospun fibers (FSP-Ins fibers) in solution and thereby affect fiber properties such as accessible surface hydrophilicity, physical stability, and release characteristics of an encapsulated drug. Interactions between insulin-loaded protein fibers and five anionic surfactants (sodium taurocholate, sodium taurodeoxycholate, sodium glycocholate, sodium glycodeoxycholate, and sodium dodecyl sulfate), a cationic surfactant (benzalkonium chloride), and a neutral surfactant (Triton X-100) were studied. The anionic surfactants increased the insulin release in a concentration-dependent manner, whereas the neutral surfactant had no significant effect on the release. Interestingly, only minute amounts of insulin were released from the fibers when benzalkonium chloride was present. The FSP-Ins fibers appeared dense after incubation with this cationic surfactant, whereas high fiber porosity was observed after incubation with anionic or neutral surfactants. Contact angle measurements and staining with the hydrophobic dye 8-anilino-1-naphthalenesulfonic acid indicated that the FSP-Ins fibers were hydrophobic, and showed that the fiber surface properties were affected differently by the surfactants. Bovine serum albumin also affected insulin release in vitro, indicating that also proteins may affect the fiber performance in an in vivo setting. PMID:26389817

  9. Wettability alteration by trimeric cationic surfactant at water-wet/oil-wet mica mineral surfaces

    International Nuclear Information System (INIS)

    The wettability of oil reservoir rock affects the efficiency of the oil recovery process by reducing the capillary force. Methyldodecylbis [2-(dimethyldodecylammonio) ethyl] ammonium tribromide is a trimeric cationic surfactant that contains three dodecyl chains and three quaternary ammonium head groups connected by divinyl groups. The surfactant was synthesized, purified and used as a new wetting alteration agent. This paper focuses on the ability of this trimeric cationic surfactant to alter the wettability of water-wet and oil-wet mica mineral surfaces. The contact angle data of the solid-liquid interface in oil/water/solid three-phase system show that the trimeric cationic surfactant, when compared with single- and double-chain cationic surfactant, is a more effective wetting agent for water-wet and oil-wet mica surfaces at lower concentration. Measurements by atomic force microscopy (AFM) show that the surfactant molecules have formed a monolayer to reverse the wetting properties. On the water-wet surface, the surface is suffused with negative charge, which could attract the cationic head of surfactant, and leave the hydrophobic tails exposed. In contrast, on the oil-wet surface, the hydrophobic tails were attracted by hydrophobic interactions to the oil film between the surfactant and the crude oil. The hydrophilic heads were left outside to form a hydrophilic layer, which could explain the wettable to hydrophilic trend. Alteration to the degree of wettability is mainly dependent on the adsorption areas of the surfactant. The data show that the ability of the trimeric cationic surfactant affect the wettability is independent of surface tension.

  10. Neonatal varicella pneumonia, surfactant replacement therapy

    Directory of Open Access Journals (Sweden)

    Mousa Ahmadpour-kacho

    2015-12-01

    Full Text Available Background: Chickenpox is a very contagious viral disease that caused by varicella-zoster virus, which appears in the first week of life secondary to transplacental transmission of infection from the affected mother. When mother catches the disease five days before and up to two days after the delivery, the chance of varicella in neonate in first week of life is 17%. A generalized papulovesicular lesion is the most common clinical feature. Respiratory involvement may lead to giant cell pneumonia and respiratory failure. The mortality rate is up to 30% in the case of no treatment, often due to pneumonia. Treatment includes hospitalization, isolation and administration of intravenous acyclovir. The aim of this case report is to introduce the exogenous surfactant replacement therapy after intubation and mechanical ventilation for respiratory failure in neonatal chickenpox pneumonia and respiratory distress. Case Presentation: A seven-day-old neonate boy was admitted to the Neonatal Intensive Care Unit at Amirkola Children’s Hospital, Babol, north of Iran, with generalized papulovesicular lesions and respiratory distress. His mother has had a history of Varicella 4 days before delivery. He was isolated and given supportive care, intravenous acyclovir and antibiotics. On the second day, he was intubated and connected to mechanical ventilator due to severe pneumonia and respiratory failure. Because of sever pulmonary involvement evidenced by Chest X-Ray and high ventilators set-up requirement, intratracheal surfactant was administered in two doses separated by 12 hours. He was discharged after 14 days without any complication with good general condition. Conclusion: Exogenous surfactant replacement therapy can be useful as an adjunctive therapy for the treatment of respiratory failure due to neonatal chickenpox.

  11. Adsorption Behavior and Mechanisms of Surfactants by Farmland Soils in Northeast China

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    The adsorption of two nonionic surfactants polyethylene glycol tert-octylphenyl ether Triton X-100 (TX-100), polyoxyethylene lauryl ether(Brij35) and an anionic surfactant sodium dodecyl benzene sulfonate(SDBS) by two soils(S1, S2) of different natures and their respective organic-matter-extracted samples(S3, S4) were investigated. These adsorption isotherms show different adsorption stages of different types of surfactants by soils. The data fitted Langmuir equation very well. The adsorption maximum capacity(Q0) indicates that TX-100 and SDBS were in the sequence of S3〉S4〉S1〉S2 in adsorption, however, Brij35 was in the sequence of S4〉S3〉S1〉S2 in adsorption. And the adsorption amounts of the different surfactants by soils followed the order of TX-100〉Brij35〉SDBS. Meanwhile, the adsorption of the nonionic surfactants TX-100 and Brij35 decreased with the increase of their ethylene oxide(EO) numbers. The results indicate that both soil organic matter and mineral played important roles in the adsorption of surfactants, and the adsorption of the surfactants by soils was affected by the physicochemical properties and structures of the soils and surfactants, especially the mineral type and content of soil.

  12. Functional significance and control of release of pulmonary surfactant in the lizard lung.

    Science.gov (United States)

    Wood, P G; Daniels, C B; Orgeig, S

    1995-10-01

    The amount of pulmonary surfactant in the lungs of the bearded dragon (Pogona vitticeps) increases with increasing body temperature. This increase coincides with a decrease in lung compliance. The relationship between surfactant and lung compliance and the principal stimuli for surfactant release and composition (temperature, ventilatory pattern, and autonomic neurotransmitters) were investigated. We chose to investigate ventilatory pattern (which causes mechanical deformation of the type II cells) and adrenergic agents, because they are the major stimuli for surfactant release in mammals. To examine the effects of body temperature and ventilatory pattern, isolated lungs were ventilated at either 18 or 37 degrees C at different ventilatory regimens. An isolated perfused lung preparation at 27 degrees C was used to analyze the effects of autonomic neurotransmitters. Ventilatory pattern did not affect surfactant release, composition, or lung compliance at either 18 or 37 degrees C. An increase in temperature increased phospholipid reuptake and disproportionately increased cholesterol degradation/uptake. Epinephrine and acetylcholine stimulated phospholipid but not cholesterol release. Removal of surfactant caused a decrease in compliance, regardless of the experimental temperature. Temperature appears to be the principal determinant of lung compliance in the bearded dragon, acting directly to increase the tone of the smooth muscle. Increasing the ambient temperature may result in greater surfactant turnover by increasing cholesterol reuptake/degradation directly and by increasing circulating epinephrine, thereby indirectly increasing phospholipid secretion. We suggest that changing ventilatory pattern may be inadequate as a mechanism for maintaining surfactant homeostasis, given the discontinuous, highly variable reptilian breathing pattern. PMID:7485601

  13. The effect of surfactants on the dissolution behavior of amorphous formulations.

    Science.gov (United States)

    Mah, Pei T; Peltonen, Leena; Novakovic, Dunja; Rades, Thomas; Strachan, Clare J; Laaksonen, Timo

    2016-06-01

    The optimal design of oral amorphous formulations benefits from the use of excipients to maintain drug supersaturation and thus ensures adequate absorption during intestinal transit. The use of surfactants for the maintenance of supersaturation in amorphous formulations has not been investigated in detail. The main aim of this study was to investigate the effect of surfactant on the dissolution behavior of neat amorphous drug and binary polymer based solid dispersion. Indomethacin was used as the model drug and the surfactants studied were polysorbate 80 and poloxamer 407. The presence of surfactants (alone or in combination with polymers) in the buffer was detrimental to the dissolution of neat amorphous indomethacin, suggesting that the surfactants promoted the crystallization of neat amorphous indomethacin. In contrast, the presence of surfactants (0.01% w/v) in the buffer resulted in a significant improvement on the dissolution behavior of binary polymer based solid dispersion. Incorporating the surfactant to the formulation to form ternary solid dispersion adversely affected the dissolution behavior. In conclusion, the use of surfactants (as wetting or solubilization agents) in dissolution studies of neat amorphous drugs requires prudent consideration. The design of amorphous formulations with optimal dissolution performance requires the appropriate selection of a combination of excipients and consideration of the method of introducing the excipients. PMID:26955750

  14. Solution rheology of polyelectrolytes and polyelectrolyte-surfactant systems

    Science.gov (United States)

    Plucktaveesak, Nopparat

    The fundamental understanding of polyelectrolytes in aqueous solutions is an important branch of polymer research. In this work, the rheological properties of polyelectrolytes and polyelectrolyte/surfactant systems are studied. Various synthetic poly electrolytes are chosen with varied hydrophobicity. We discuss the effects of adding various surfactants to aqueous solutions of poly(ethylene oxide)-b-poly(propylene oxide)- b-polyethylene oxide)-g-poly(acrylic acid) (PEO-PPO-PAA) in the first chapter. Thermogelation in aqueous solutions of PEO-PPO-PAA is due to micellization caused by aggregation of poly(propylene oxide) (PPO) blocks resulting from temperature-induced dehydration of PPO. When nonionic surfactants with hydrophilic-lipophilic balance (HLB) parameter exceeding 11 or Cn alkylsulfates; n-octyl (C8), n-decyl (C 10) and n-dodecyl (C12) sulfates are added, the gelation threshold temperature (Tgel) of 1.0wt% PEO-PPO-PAA in aqueous solutions increases. In contrast, when nonionic surfactants with HLB below 11 are added, the gelation temperature decreases. On the other hand, alkylsulfates with n = 16 or 18 and poly(ethylene oxide) (PEO) do not affect the Tgel. The results imply that both hydrophobicity and tail length of the added surfactant play important roles in the interaction of PEO-PPO-PAA micelles and the surfactant. In the second chapter, the solution behavior of alternating copolymers of maleic acid and hydrophobic monomer is studied. The alternating structure of monomers with two-carboxylic groups and hydrophobic monomers make these copolymers unique. Under appropriate conditions, these carboxylic groups dissociate leaving charges on the chain. The potentiometric titrations of copolymer solutions with added CaCl2 reveal two distinct dissociation processes corresponding to the dissociation of the two adjacent carboxylic acids. The viscosity data as a function of polymer concentration of poly(isobutylene-alt-sodium maleate), poly

  15. Single-Molecule Denaturation Mapping of DNA in Nanofluidic Channels

    Science.gov (United States)

    Reisner, Walter; Larsen, Niels; Silahtaroglu, Asli; Kristensen, Anders; Tommerup, Niels; Tegenfeldt, Jonas O.; Flyvbjerg, Henrik

    2010-03-01

    Nanochannel based DNA stretching can serve as a platform for a new optical mapping technique based on measuring the pattern of partial melting along the extended molecules. We partially melt DNA extended in nanofluidic channels via a combination of local heating and added chemical denaturants. The melted molecules, imaged via a standard fluorescence videomicroscopy setup, exhibit a nonuniform fluorescence profile corresponding to a series of local dips and peaks in the intensity trace along the stretched molecule. We show that this barcode is consistent with the presence of locally melted regions along the molecule and can be explained by calculations of sequence-dependent melting probability. Specifically, we obtain experimental melting profiles for T4, T7, lambda-phage and bacterial artificial chromosome DNA (from human chromosome 12) and compare these profiles to theory. In addition, we demonstrate that the BAC melting profile can be used to align the BAC to its correct position on chromosome 12.

  16. Inactivation of pulmonary surfactant and its prevention

    OpenAIRE

    Stichtenoth, Guido

    2009-01-01

    Pulmonary surfactant is a lipoprotein complex coating the conducting airways down to the terminal airspaces. Its main function is to lower surface tension at the air liquid interface thus preventing alveolar collapse at end expiration. Primary surfactant deficiency is the main cause of neonatal respiratory distress syndrome (RDS) and treatment with exogenous pulmonary surfactant improves the course of the disease significantly. Furthermore, secondary surfactant deficiency ca...

  17. Antigenicity of low molecular weight surfactant species.

    OpenAIRE

    Strayer, D. S.; Merritt, T A; Makunike, C.; Hallman, M

    1989-01-01

    The authors tested the antigenicity of human lung surfactant isolated from amniotic fluid. Mice and rabbits were immunized. Rabbit polyclonal antisera to these surfactant preparations were absorbed with normal human plasma proteins. Polyclonal antisera reacted with both high molecular weight (35 kd) surfactant apoprotein and to lower molecular weight species, both 18 kd and 9 kd. Mice were used to generate monoclonal antibodies to surfactant. Enzyme-linked immunosorbant assay was used to iden...

  18. Surfactant Therapy of ALI and ARDS

    OpenAIRE

    Raghavendran, K; Willson, D; Notter, RH

    2011-01-01

    This article examines exogenous lung surfactant replacement therapy and its utility in mitigating clinical acute lung injury (ALI) and the acute respiratory distress syndrome (ARDS). Biophysical research has documented that lung surfactant dysfunction can be reversed or mitigated by increasing surfactant concentration, and multiple studies in animals with ALI/ARDS have shown that respiratory function and pulmonary mechanics in vivo can be improved by exogenous surfactant administration. Exoge...

  19. Aerosol delivery of synthetic lung surfactant

    OpenAIRE

    Walther, Frans J.; José M. Hernández-Juviel; Waring, Alan J.

    2014-01-01

    Background. Nasal continuous positive airway pressure (nCPAP) is a widely accepted technique of non-invasive respiratory support in premature infants with respiratory distress syndrome due to lack of lung surfactant. If this approach fails, the next step is often intubation, mechanical ventilation (MV) and intratracheal instillation of clinical lung surfactant. Objective. To investigate whether aerosol delivery of advanced synthetic lung surfactant, consisting of peptide mimics of surfact...

  20. Thin film dynamics with surfactant phase transition

    OpenAIRE

    Köpf, M. H.; Gurevich, S. V.; Friedrich, R.

    2009-01-01

    A thin liquid film covered with an insoluble surfactant in the vicinity of a first-order phase transition is discussed. Within the lubrication approximation we derive two coupled equations to describe the height profile of the film and the surfactant density. Thermodynamics of the surfactant is incorporated via a Cahn-Hilliard type free-energy functional which can be chosen to describe a transition between two stable phases of different surfactant density. Within this model, a linear stabilit...

  1. Interaction between cationic surfactant of 1-methyl-3-tetradecylimidazolium bromide and anionic polymer of sodium polystyrene sulfonate

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Qian [College of Chemistry and Chemical Engineering, Liaocheng University, Shandong Province, VIC 252059 (China); School of Chemistry and Chemical Engineering, Engineering Research Center for Fine Chemicals of Ministry of Education, Shanxi University, Shanxi Province, VIC 030006 (China); Kang, Wenpei [Key Laboratory of Colloid and Interface Chemistry, Shandong University, Ministry of Education, Shandong Province, VIC 250100 (China); Sun, Dezhi [College of Chemistry and Chemical Engineering, Liaocheng University, Shandong Province, VIC 252059 (China); Liu, Jie, E-mail: liujie@lcu.edu.cn [College of Chemistry and Chemical Engineering, Liaocheng University, Shandong Province, VIC 252059 (China); Wei, Xilian, E-mail: weixilian@126.com [College of Chemistry and Chemical Engineering, Liaocheng University, Shandong Province, VIC 252059 (China)

    2013-08-15

    The interaction between long-chain imidazolium ionic liquid (C{sub 14}mimBr) and anionic polyelectrolyte of sodium polystyrene sulfonate (NaPSS) has been studied using surface tension, isothermal titration microcalorimetry (ITC), dynamic light scatting (DLS) and conductance methods. The result shows that the surface tension plots have a pronounced hump in the surface tension at surfactant concentrations below the critical micelle concentration (cmc) of the surfactant. The cooperative adsorption of surfactant and polymer on the surface (PS{sub S}) and the formation of polymer/surfactant aggregate in bulk solution (PS{sub M}) provide a rational explanation about it. The formation of surfactant/polymer complexes is affected by the concentration of the surfactant or NaPSS, which is also ascertained by ITC and DLS measurements. Further, the thermodynamic parameters are derived from calorimetric titration and conductance curves, and the effects of polymer concentration and temperature on the parameters are evaluated in detail.

  2. Interaction between cationic surfactant of 1-methyl-3-tetradecylimidazolium bromide and anionic polymer of sodium polystyrene sulfonate

    International Nuclear Information System (INIS)

    The interaction between long-chain imidazolium ionic liquid (C14mimBr) and anionic polyelectrolyte of sodium polystyrene sulfonate (NaPSS) has been studied using surface tension, isothermal titration microcalorimetry (ITC), dynamic light scatting (DLS) and conductance methods. The result shows that the surface tension plots have a pronounced hump in the surface tension at surfactant concentrations below the critical micelle concentration (cmc) of the surfactant. The cooperative adsorption of surfactant and polymer on the surface (PSS) and the formation of polymer/surfactant aggregate in bulk solution (PSM) provide a rational explanation about it. The formation of surfactant/polymer complexes is affected by the concentration of the surfactant or NaPSS, which is also ascertained by ITC and DLS measurements. Further, the thermodynamic parameters are derived from calorimetric titration and conductance curves, and the effects of polymer concentration and temperature on the parameters are evaluated in detail.

  3. The interfacial interactions of Tb-doped silica nanoparticles with surfactants and phospholipids revealed through the fluorescent response.

    Science.gov (United States)

    Bochkova, Olga D; Mustafina, Asiya R; Mukhametshina, Alsu R; Burilov, Vladimir A; Skripacheva, Viktoriya V; Zakharova, Lucia Ya; Fedorenko, Svetlana V; Konovalov, Alexander I; Soloveva, Svetlana E; Antipin, Igor S

    2012-04-01

    The quenching effect of dyes (phenol red and bromothymol blue) on Tb(III)-centered luminescence enables to sense the aggregation of cationic and anionic surfactants near the silica surface of Tb-doped silica nanoparticles (SN) in aqueous solutions. The Tb-centered luminescence of non-decorated SNs is diminished by the inner filter effect of both dyes. The decoration of the silica surface by cationic surfactants induces the quenching through the energy transfer between silica coated Tb(III) complexes and dye anions inserted into surfactant aggregates. Thus the distribution of surfactants aggregates at the silica/water interface and in the bulk of solution greatly affects dynamic quenching efficiency. The displacement of dye anions from the interfacial surfactant adlayer by anionic surfactants and phospholipids is accompanied by the "off-on" switching of Tb(III)-centered luminescence. PMID:22209651

  4. Fabrication of novel microstructures based on orientation-dependent adsorption of surfactant molecules in a TMAH solution

    International Nuclear Information System (INIS)

    In this work, the orientation-dependent adsorption of surfactant molecules on the silicon surface during etching in surfactant-added tetramethylammonium hydroxide (TMAH) is investigated. Triton X-100 (C14H22O(C2H4O)n, n = 9–10) and 25 wt% TMAH are used as surfactant and main etchant, respectively. The crystallographic planes affected by the surfactant molecules are determined by analyzing the etching behavior of different mask patterns on Si{1 0 0} wafers and silicon hemispheres in pure and surfactant-added TMAH. Taken together, the shapes of the etched profiles and the analysis of the hemispherical etch rates confirm that thick and dense adsorbed surfactant layers are typically formed on both the exact and vicinal Si{1 1 0} surfaces. In addition, the results indicate that the adsorbed surfactant layer behaves as a permeable mask, partially slowing down the etch rate of the affected surface orientation/s and thus enforcing their appearance on the etching front. The peculiar etching properties of surfactant-added and surfactant-free TMAH are then utilized for the fabrication of advanced micromechanical structures with new shapes on Si{1 0 0} wafers and polydimethylsiloxane based on complex Si{1 0 0} molds.

  5. Comparative effect of microwaves and boiling on the denaturation of DNA

    Energy Technology Data Exchange (ETDEWEB)

    Stroop, W.G.; Schaefer, D.C. (Veterans Administration Medical Center, Salt Lake City, UT (USA))

    1989-11-01

    The effect of heat and microwave denaturation of small volumes of double-stranded plasmid DNA has been compared. Samples of intact plasmid DNA had plasmid DNA linearized by digestion with EcoRI were conventionally denatured in a boiling water bath or denatured by 2450 MHz of microwave energy for 0-300 s. Heat denaturation for periods longer than 120 s caused breakdown of linearized plasmid DNA; however, microwave denaturation for 10-300 s caused no apparent degradation of linearized DNA. Breakdown of DNA forms II and III was noted in plasmid DNA subjected to 300 s of either heat or microwave denaturation but breakdown of forms II and III occurred more quickly with heat than with microwave treatment. Microwave treatment was also found to be better than heat to denature 32P-labeled DNA probes subsequently used to detect homologous DNA samples immobilized on nitrocellulose filters. A microwave-treated 32P-labeled DNA probe was able to hybridize to DNA samples 20 times more dilute than a heat-treated 32P-labeled DNA probe. Depending on the form of DNA to be analyzed, these results indicate that small volumes of DNA solutions and radiolabeled DNA probes can be effectively denatured in a conventional microwave oven.

  6. Comparative effect of microwaves and boiling on the denaturation of DNA

    International Nuclear Information System (INIS)

    The effect of heat and microwave denaturation of small volumes of double-stranded plasmid DNA has been compared. Samples of intact plasmid DNA had plasmid DNA linearized by digestion with EcoRI were conventionally denatured in a boiling water bath or denatured by 2450 MHz of microwave energy for 0-300 s. Heat denaturation for periods longer than 120 s caused breakdown of linearized plasmid DNA; however, microwave denaturation for 10-300 s caused no apparent degradation of linearized DNA. Breakdown of DNA forms II and III was noted in plasmid DNA subjected to 300 s of either heat or microwave denaturation but breakdown of forms II and III occurred more quickly with heat than with microwave treatment. Microwave treatment was also found to be better than heat to denature 32P-labeled DNA probes subsequently used to detect homologous DNA samples immobilized on nitrocellulose filters. A microwave-treated 32P-labeled DNA probe was able to hybridize to DNA samples 20 times more dilute than a heat-treated 32P-labeled DNA probe. Depending on the form of DNA to be analyzed, these results indicate that small volumes of DNA solutions and radiolabeled DNA probes can be effectively denatured in a conventional microwave oven

  7. 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.)

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

    International Nuclear Information System (INIS)

    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.)

  9. Nucleolin enhances the proliferation and migration of heat-denatured human dermal fibroblasts.

    Science.gov (United States)

    Jiang, Bimei; Li, Yuanbin; Liang, Pengfei; Liu, Yanjuan; Huang, Xu; Tong, Zhongyi; Zhang, Pihong; Huang, Xiaoyuan; Liu, Ying; Liu, Zhenguo

    2015-01-01

    Denatured dermis, a part of dermis in burned skin, has the ability to restore its normal morphology and functions after their surrounding microenvironment is improved. However, the cellular and molecular mechanisms by which the denatured dermis could improve wound healing are still unclear. This study aimed to investigate the role of nucleolin during the recovery of heat-denatured human dermal fibroblasts. Nucleolin mRNA and protein expression were significantly increased time-dependently during the recovery of heat-denatured human dermal fibroblasts (52 °C, 30 seconds). Heat-denaturation promoted a time-dependent cell proliferation, migration, chemotaxis, and scratched wound healing during the recovery of human dermal fibroblasts. These effects were prevented by knockdown of nucleolin expression with small interference RNA (siRNA), whereas overexpression of nucleolin enhanced cell proliferation, migration, and chemotaxis of human dermal fibroblasts with heat-denaturation. In addition, the expression of transforming growth factor-beta 1(TGF-β1) was significantly increased during the recovery of heat-denatured dermis and human dermal fibroblasts. TGF-β1 expression was up-regulated by nucleolin in human dermal fibroblasts. The results suggest that nucleolin expression is up-regulated, and play an important role in promoting cell proliferation, migration, and chemotaxis of human dermal fibroblasts during the recovery of heat-denatured dermis with a mechanism probably related to TGF-β1. PMID:26148015

  10. Thermal denaturation of Peyrard-Bishop's DNA model with external force

    CERN Document Server

    Sulaimana, A; Alatas, H; Handoko, L T

    2011-01-01

    The impact of external force to Peyrard-Bishop DNA denaturation is investigated through statistical mechanics approach. The partition function is obtained using transfer integral method, and further the stretching of hydrogen bond is calculated using time independent perturbation method. It is shown that the external force accelerates the denaturation processes at lower temperature

  11. 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.

  12. Persurf, a new method to improve surfactant delivery: a study in surfactant depleted rats.

    Directory of Open Access Journals (Sweden)

    Wolfram Burkhardt

    Full Text Available PURPOSE: Exogenous surfactant is not very effective in adults with ARDS, since surfactant does not reach atelectatic alveoli. Perfluorocarbons (PFC can recruit atelectatic areas but do not replace impaired endogenous surfactant. A surfactant-PFC-mixture could combine benefits of both therapies. The aim of the proof-of-principal-study was to produce a PFC-in-surfactant emulsion (Persurf and to test in surfactant depleted Wistar rats whether Persurf achieves I. a more homogenous pulmonary distribution and II. a more homogenous recruitment of alveoli when compared with surfactant or PFC alone. METHODS: Three different PFC were mixed with surfactant and phospholipid concentration in the emulsion was measured. After surfactant depletion, animals either received 30 ml/kg of PF5080, 100 mg/kg of stained (green dye Curosurf™ or 30 ml/kg of Persurf. Lungs were fixated after 1 hour of ventilation and alveolar aeration and surfactant distribution was estimated by a stereological approach. RESULTS: Persurf contained 3 mg/ml phospholipids and was stable for more than 48 hours. Persurf-administration improved oxygenation. Histological evaluation revealed a more homogenous surfactant distribution and alveolar inflation when compared with surfactant treated animals. CONCLUSIONS: In surfactant depleted rats administration of PFC-in-surfactant emulsion leads to a more homogenous distribution and aeration of the lung than surfactant alone.

  13. Nanofiltration: ion exchange system for effective surfactant removal from water solutions

    Directory of Open Access Journals (Sweden)

    I. Kowalska

    2014-12-01

    Full Text Available A system combining nanofiltration and ion exchange for highly effective separation of anionic surfactant from water solutions was proposed. The subjects of the study were nanofiltration polyethersulfone membranes and ion-exchange resins differing in type and structure. The quality of the treated solution was affected by numerous parameters, such as quality of the feed solution, membrane cut-off, resin type, dose and the solution contact time with the resin. A properly designed purification system made it possible to reduce the concentration of anionic surfactant below 1 mg L-1 from feed solutions containing surfactant in concentrations above the CMC value.

  14. Use of anionic denaturing detergents to purify insoluble proteins after overexpression

    Directory of Open Access Journals (Sweden)

    Schlager Benjamin

    2012-12-01

    Full Text Available Background Many proteins form insoluble protein aggregates, called “inclusion bodies”, when overexpressed in E. coli. This is the biggest obstacle in biotechnology. Ever since the reversible denaturation of proteins by chaotropic agents such as urea or guanidinium hydrochloride had been shown, these compounds were predominantly used to dissolve inclusion bodies. Other denaturants exist but have received much less attention in protein purification. While the anionic, denaturing detergent sodiumdodecylsulphate (SDS is used extensively in analytical SDS-PAGE, it has rarely been used in preparative purification. Results Here we present a simple and versatile method to purify insoluble, hexahistidine-tagged proteins under denaturing conditions. It is based on dissolution of overexpressing bacterial cells in a buffer containing sodiumdodecylsulfate (SDS and whole-lysate denaturation of proteins. The excess of detergent is removed by cooling and centrifugation prior to affinity purification. Host- and overexpressed proteins do not co-precipitate with SDS and the residual concentration of detergent is compatible with affinity purification on Ni/NTA resin. We show that SDS can be replaced with another ionic detergent, Sarkosyl, during purification. Key advantages over denaturing purification in urea or guanidinium are speed, ease of use, low cost of denaturant and the compatibility of buffers with automated FPLC. Conclusion Ionic, denaturing detergents are useful in breaking the solubility barrier, a major obstacle in biotechnology. The method we present yields detergent-denatured protein. Methods to refold proteins from a detergent denatured state are known and therefore we propose that the procedure presented herein will be of general application in biotechnology.

  15. Binding of cationic surfactants to DNA, protein and DNA-protein mixtures.

    Science.gov (United States)

    Gani, S A; Chattoraj, D K; Mukherjee, D C

    1999-06-01

    Extent of binding (gamma 2(1)) of cationic surfactants cetyltrimethyl ammonium bromide (CTAB), myristyltrimethyl ammonium bromide (MTAB) and dodecyl trimethyl ammonium bromide (DTAB) to calf-thymus DNA, bovine serum albumin (BSA) and to their binary mixture respectively have been measured as function of bulk concentration of the surfactant by using equilibrium dialysis technique. Binding of CTAB has been studied at different pH, ionic strength (mu), temperature and biopolymer composition and with native and denatured states of the biopolymers. The chain-length of different long chain amines plays a significant role in the extent of binding under identical solution condition. The binding ratios for CTAB to collagen, gelatin, DNA-collagen and DNA-gelatin mixtures respectively have also been determined. The conformational structures of different biopolymers are observed to play significant role in macromolecular interactions between protein and DNA in the presence of CTAB. From the experimental values of the maximum binding ratio (gamma 2m) at the saturation level for each individual biopolymer, ideal values (gamma 2m)id have been theoretically calculated for binary mixtures of biopolymers using additivity rule. The protein-DNA-CTAB interaction in mixture has been explained in terms of the deviation (delta) of (gamma 2m) from (gamma 2m)id in the presence of a surfactant in bulk. The binding of surfactants to biopolymers and to their binary mixtures are compared more precisely in terms of the Gibbs' free energy decrease (-delta G degree) for the saturation of the binding sites in the biopolymers or biopolymer mixtures with the change of the bulk surfactant activity from zero to unity in the rational mole fraction scale. PMID:10650715

  16. Adsorption of cationic surfactants and their effects on the interfacial properties of quartz

    Science.gov (United States)

    Jia, Renhe

    This dissertation is primarily concerned with an investigation of the interfacial behavior of natural quartz in aqueous solution where the adsorption of various cationic surfactants is involved. The broad objective of this research was to delineate the mechanisms involved in the adsorption of cationic surfactants using experimental determination of adsorption isotherms, zeta potentials, suspension turbidity, contact angles, induction times, as well as Hallimond tube flotation response. With dodecylpyridinium chloride as the model surfactant, four-region adsorption isotherms were observed and found to correlate well with zeta potential, suspension stability and contact angle measurements. Calculations of adsorption energy showed strong specific adsorption in Region I, probably resulting from H-bonding of the pyridinium headgroup to active sites on the silica. As a result of hemimicelle formation at the solid-liquid interface in Region II, pronounced increases in the adsorption density, zeta potential, and surface hydrophobicity were observed. The stability of quartz suspensions showed a significant drop in this region. In Region III, the zeta potential is reversed and the stability of the suspensions begins to increase again. In this region, the surface hydrophobicity of quartz decreases with further surfactant adsorption, suggesting reverse orientation of the adsorbed surfactant ions. In Region IV, the adsorption isotherm and zeta potential reach a plateau when the surfactant concentration reaches the CMC, and the surface becomes completely hydrophilic. The molecular structure of surfactant ions (chain length, number of hydrocarbon chains and number of headgroups) was found to significantly affect their surface activity. Increasing the hydrocarbon chain length of the surfactant lowers the concentration of surfactant required for minimum suspension stability, as well as redispersion. The adsorption is stronger for surfactants whose structure permits hydrogen bonding

  17. Surfactant and allergic airway inflammation.

    Science.gov (United States)

    Winkler, Carla; Hohlfeld, Jens M

    2013-01-01

    Pulmonary surfactant is a complex mixture of unique proteins and lipids that covers the airway lumen. Surfactant prevents alveolar collapse and maintains airway patency by reducing surface tension at the air-liquid interface. Furthermore, it provides a defence against antigen uptake by binding foreign particles and enhancing cellular immune responses. Allergic asthma is associated with chronic airway inflammation and presents with episodes of airway narrowing. The pulmonary inflammation and bronchoconstriction can be triggered by exposure to allergens or pathogens present in the inhaled air. Pulmonary surfactant has the potential to interact with various immune cells which orchestrate allergen- or pathogen-driven episodes of airway inflammation. The complex nature of surfactant allows multiple sites of interaction, but also makes it susceptible to external alterations, which potentially impair its function. This duality of modulating airway physiology and immunology during inflammatory conditions, while at the same time being prone to alterations accompanied by restricted function, has stimulated numerous studies in recent decades, which are reviewed in this article. PMID:23896983

  18. Interactions of Ovalbumin with Ionic Surfactants

    Institute of Scientific and Technical Information of China (English)

    GUO Xia; YAN Hui; GUO Rong

    2008-01-01

    The interactions of ovalbumin (OVA) with one anionic surfactant,sodium dodecyl sulfate (SDS),and two cationic surfactants,dodecyl trimethylammonium bromide (DTAB) and cetyl trimethylammonium bromide (CTAB),in water have been studied through fluorescence and UV-Vis spectroscopies and transmission electronic microscopy,combined with the measurement of conductivity.OVA can increase the critical micelle concentrations (cmc) of SDS and CTAB but has little effect on that of DTAB.The interaction between surfactant monomer and OVA is greater than that between surfactant micelles and OVA.Moreover,SDS can make OVA unfolded while cationic surfactants cannot.

  19. Surfactant gene polymorphisms and interstitial lung diseases

    Directory of Open Access Journals (Sweden)

    Pantelidis Panagiotis

    2001-11-01

    Full Text Available Abstract Pulmonary surfactant is a complex mixture of phospholipids and proteins, which is present in the alveolar lining fluid and is essential for normal lung function. Alterations in surfactant composition have been reported in several interstitial lung diseases (ILDs. Furthermore, a mutation in the surfactant protein C gene that results in complete absence of the protein has been shown to be associated with familial ILD. The role of surfactant in lung disease is therefore drawing increasing attention following the elucidation of the genetic basis underlying its surface expression and the proof of surfactant abnormalities in ILD.

  20. Effect of surfactant and surfactant blends on pseudoternary phase diagram behavior of newly synthesized palm kernel oil esters

    Directory of Open Access Journals (Sweden)

    Mahdi ES

    2011-06-01

    Full Text Available Elrashid Saleh Mahdi1, Mohamed HF Sakeena1, Muthanna F Abdulkarim1, Ghassan Z Abdullah1,3, Munavvar Abdul Sattar2, Azmin Mohd Noor11Department of Pharmaceutical Technology, 2Department of Physiology, School of Pharmaceutical Sciences, Universiti Sains Malaysia, Minden, Penang, Malaysia; 3Department of Pharmaceutical Technology, International Medical University, Bukit Jalil, Kuala Lumpur, MalaysiaBackground: The purpose of this study was to select appropriate surfactants or blends of surfactants to study the ternary phase diagram behavior of newly introduced palm kernel oil esters.Methods: Nonionic surfactant blends of Tween® and Tween®/Span® series were screened based on their solubilization capacity with water for palm kernel oil esters. Tween® 80 and five blends of Tween® 80/Span® 80 and Tween® 80/Span® 85 in the hydrophilic-lipophilic balance (HLB value range of 10.7–14.0 were selected to study the phase diagram behavior of palm kernel oil esters using the water titration method at room temperature.Results: High solubilization capacity was obtained by Tween® 80 compared with other surfactants of Tween® series. High HLB blends of Tween® 80/Span® 85 and Tween® 80/Span® 80 at HLB 13.7 and 13.9, respectively, have better solubilization capacity compared with the lower HLB values of Tween® 80/Span® 80. All the selected blends of surfactants were formed as water-in-oil microemulsions, and other dispersion systems varied in size and geometrical layout in the triangles. The high solubilization capacity and larger areas of the water-in-oil microemulsion systems were due to the structural similarity between the lipophilic tail of Tween® 80 and the oleyl group of the palm kernel oil esters.Conclusion: This study suggests that the phase diagram behavior of palm kernel oil esters, water, and nonionic surfactants is not only affected by the HLB value, but also by the structural similarity between palm kernel oil esters and the surfactant

  1. Surfactants and Superhydrophobic Surfaces

    OpenAIRE

    Ferrari, Michele; Ravera, Francesca; Liggieri, Libero

    2006-01-01

    On superhydrophobic surfaces (contact angle with water greater than 150?), liquid drainage is enhanced with inhibition of adhesion phenomena: the small area shown when in contact with water make interactions in this environment usually strongly limited. The extreme hydrophobicity of a solid substrate is governed by chemical composition and geometrical structure of the surface including physico-chemical conditions acting from micro to nanoscale affecting the organisation of material at the int...

  2. Biopolymer Surfactant Interactions

    OpenAIRE

    Sreejith, Lisa; Nair, S.M.; George, Jinu

    2010-01-01

    The effect of sodium chloride on micellar property of CTAB in biopolymer gelatin were systematically studied. It was found that, micellisation and transition is favoured by increase in concentration of sodium chloride, however, without affecting the conformation of gelatin. The main findings from the present investigation refer to the stabilizing role of salt in presence of a biopolymer, gelatin, in micellar media. Increase in viscosity and gel

  3. 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).

  4. Thermally responsive silicon nanowire arrays for native/denatured-protein separation

    Science.gov (United States)

    Wang, Hongwei; Wang, Yanwei; Yuan, Lin; Wang, Lei; Yang, Weikang; Wu, Zhaoqiang; Li, Dan; Chen, Hong

    2013-03-01

    We present our findings of the selective adsorption of native and denatured proteins onto thermally responsive, native-protein resistant poly(N-isopropylacrylamide) (PNIPAAm) decorated silicon nanowire arrays (SiNWAs). The PNIPAAm-SiNWAs surface, which shows very low levels of native-protein adsorption, favors the adsorption of denatured proteins. The amount of denatured-protein adsorption is higher at temperatures above the lower critical solution temperature (LCST) of PNIPAAm. Temperature cycling surrounding the LCST, which ensures against thermal denaturation of native proteins, further increases the amount of denatured-protein adsorption. Moreover, the PNIPAAm-SiNWAs surface is able to selectively adsorb denatured protein even from mixtures of different protein species; meanwhile, the amount of native proteins in solution is kept nearly at its original level. It is believed that these results will not only enrich current understanding of protein interactions with PNIPAAm-modified SiNWAs surfaces, but may also stimulate applications of PNIPAAm-SiNWAs surfaces for native/denatured protein separation.

  5. Visualization of alkali-denatured supercoiled plasmid DNA by atomic force microscopy

    International Nuclear Information System (INIS)

    To study the alkali denaturation of supercoiled DNA, plasmid pBR322 was treated with gradient concentrations of NaOH solution. The results of gel electrophoresis showed that the alkali denaturation of the supercoiled DNA occurred in a narrow range of pH value (12.88-12.90). The alkali-denatured supercoiled DNA ran, as a sharp band, faster than the supercoiled DNA. The supercoiled plasmid DNA of pBR322, pACYC184 and pJGX15A were denatured by NaOH, and then visualized by atomic force microscopy. Compared with the supercoiled DNA, the atomic force microscopy images of the alkali-denatured supercoiled DNA showed rough surface with many kinks, bulges on double strands with inhomogeneous diameters. The apparent contour lengths of the denatured DNA were shortened by 16%, 16% and 50% for pBR322, pACYC184 and pJGX15A, respectively. All evidence suggested that the alkali-denatured supercoiled DNA had a stable conformation with unregistered, topologically constrained double strands and intrastrand secondary structure

  6. 27 CFR 19.41 - Claims on spirits, denatured spirits, articles, or wines lost or destroyed in bond.

    Science.gov (United States)

    2010-04-01

    ..., denatured spirits, articles, or wines lost or destroyed in bond. 19.41 Section 19.41 Alcohol, Tobacco... DISTILLED SPIRITS PLANTS Taxes Claims § 19.41 Claims on spirits, denatured spirits, articles, or wines lost..., relating to the destruction or loss of spirits, denatured spirits, articles, or wines in bond, shall...

  7. Renaturation of the androgen receptor after denaturation in SDS

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, M.P.; Young, C.Y.F.; Rowley, D.R.; Tindall, D.J.

    1986-05-01

    Renaturation of the steroid binding activity of receptor proteins is a potentially useful tool for their purification and analysis. Cytosol was prepared from rat Dunning prostate tumor in buffer containing molybdate and then denatured by addition of SDS buffer and heating. Aliquots were precipitated in cold acetone and the resulting pellets were washed and solubilized with a small volume of solution containing a chaotropic agent such as 6M guanidine, 8M urea, or 5M sodium iodide. After a 20-minute incubation, samples were diluted 20-fold with buffer containing 4nM (/sup 3/H)dihydrotestosterone with or without excess unlabeled dihydrotestosterone. Diluted samples were incubated at 0/sup 0/C for varying periods of time prior to assay of bound radioactivity using hydroxylapatite. A time-course of renaturation after exposure to guanidine showed a steady increase of specific binding activity during the first 7 hrs post-dilution that remained stable up to 22 hrs. Experiments with guanidine consistently demonstrated that 25-50% of binding activity was recoverable. Preliminary results using urea or sodium iodide were similar. Efforts to optimize recovery and to characterize the renatured androgen receptor are in progress.

  8. Renaturation of the androgen receptor after denaturation in SDS

    International Nuclear Information System (INIS)

    Renaturation of the steroid binding activity of receptor proteins is a potentially useful tool for their purification and analysis. Cytosol was prepared from rat Dunning prostate tumor in buffer containing molybdate and then denatured by addition of SDS buffer and heating. Aliquots were precipitated in cold acetone and the resulting pellets were washed and solubilized with a small volume of solution containing a chaotropic agent such as 6M guanidine, 8M urea, or 5M sodium iodide. After a 20-minute incubation, samples were diluted 20-fold with buffer containing 4nM [3H]dihydrotestosterone with or without excess unlabeled dihydrotestosterone. Diluted samples were incubated at 00C for varying periods of time prior to assay of bound radioactivity using hydroxylapatite. A time-course of renaturation after exposure to guanidine showed a steady increase of specific binding activity during the first 7 hrs post-dilution that remained stable up to 22 hrs. Experiments with guanidine consistently demonstrated that 25-50% of binding activity was recoverable. Preliminary results using urea or sodium iodide were similar. Efforts to optimize recovery and to characterize the renatured androgen receptor are in progress

  9. Slow closure of denaturation bubbles in DNA: Twist matters

    Science.gov (United States)

    Dasanna, Anil Kumar; Destainville, Nicolas; Palmeri, John; Manghi, Manoel

    2013-05-01

    The closure of long equilibrated denaturation bubbles in DNA is studied using Brownian dynamics simulations. A minimal mesoscopic model is used where the double helix is made of two interacting bead-spring freely rotating strands, with a nonzero torsional modulus in the duplex state, κϕ=200 to 300kBT. For DNAs of lengths N=40 to 100 base pairs (bps) with a large initial bubble in their middle, long closure times of 0.1 to 100μs are found. The bubble starts winding from both ends until it reaches a ≈10 bp metastable state due to the large elastic energy stored in the bubble. The final closure is limited by three competing mechanisms depending on κϕ and N: arms diffusion until their alignment, bubble diffusion along the DNA until one end is reached, or local Kramers process (crossing over a torsional energy barrier). For clamped ends or long DNAs, the closure occurs via this last temperature-activated mechanism, yielding a good quantitative agreement with the experiments.

  10. Calorimetric studies of the thermal denaturation of cytochrome c peroxidase

    International Nuclear Information System (INIS)

    Two endotherms are observed by differential scanning calorimetry during the thermal denaturation of cytochrome c peroxidase at pH 7.0. The transition midpoint temperatures (t/sub m/) were 43.9 +- 1.4 and 63.3 +- 1.6 0C, independent of concentration. The two endotherms were observed at all pH values between 4 and 8, with the transition temperatures varying with pH. Precipitation was observed between pH 4 and 6, and only qualitative data are presented for this region. The thermal unfolding of cytochrome c peroxidase was sensitive to the presence and ligation state of the heme. Only a single endotherm was observed for the unfolding of the apoprotein, and this transition was similar to the high-temperature transition in the holoenzyme. Addition of KCN to the holoenzyme increases the midpoint of the high-temperature transition whereas the low-temperature transition was increased upon addition of KF. Binding of the natural substrate ferricytochrome c to the enzyme increases the low-temperature transition by 4.8 +- 1.3 0C but has no effect on the high-temperature transition at pH 7. The presence of cytochrome c peroxidase decreases the stability of cytochrome c, and both proteins appear to unfold simultaneously. The results are discussed in terms of the two domains evident in the X-ray crystallographic structure of cytochrome c peroxidase

  11. Dielectric relaxations on erythrocyte membrane as revealed by spectrin denaturation.

    Science.gov (United States)

    Ivanov, I T; Paarvanova, B

    2016-08-01

    We studied the effect of spectrin denaturation at 49.5°C (TA) on the dielectric relaxations and related changes in the complex impedance, Z*, complex capacitance, C*, and dielectric loss curve of suspensions containing human erythrocytes, erythrocyte ghost membranes (EMs) and Triton-X-100 residues of EMs. The loss curve prior to, minus the loss curve after TA, resulted in a bell-shaped peak at 1.5MHz. The changes in the real and imaginary components of Z* and C* at TA, i.e., ΔZre, ΔZim, ΔCre and ΔCim, calculated in the same way, strongly varied with frequency. Between 1.0 and 12MHz the -ΔZim vs ΔZre, and ΔCim vs ΔCre plots depicted semicircles with critical frequencies, fcr, at 2.5MHz expressing recently reported relaxation of spectrin dipoles. Between 0.02 and 1.0MHz the -ΔZim vs ΔZre plot exhibited another relaxation whose fcr mirrored that of beta relaxation. This relaxation was absent on Triton-X-shells, while on erythrocytes and EMs it was inhibited by selective dissociation of either attachment sites between spectrin and bilayer. Considering above findings and inaccessibility of cytosole to outside field at such frequencies, the latter relaxation was assumed originating from a piezoelectric effect on the highly deformable spectrin filaments. PMID:27071054

  12. Foam, emulsion and wetting films stabilized by polyoxyalkylated diethylenetriamine (DETA) polymeric surfactants.

    Science.gov (United States)

    Khristov, Khr; Petkova, H; Alexandrova, L; Nedyalkov, M; Platikanov, D; Exerowa, D; Beetge, J

    2011-10-14

    This review explores three (A, B, C) polyoxyalkylated diethylenetriamine (DETA) polymeric surfactants belonging to the group of star-like polymers. They have a similar structure, differing only in the number of polymeric branches (4, 6 and 9 in the mentioned order). The differences in these surfactants' ability to stabilize foam, o/w/o and w/o/w emulsion and wetting films are evaluated by a number of methods summarized in Section 2. Results from the studies indicate that differences in polymeric surfactants' molecular structure affect the properties exhibited at air/water, oil/water and water/solid interfaces, such as the value of surface tension, interfacial tension, critical micelle concentration, degree of hydrophobicity of solid surface, etc. Foam, emulsion and wetting films stabilized by such surfactants also show different behavior regarding some specific parameters, such as critical electrolyte concentration, surfactant concentration for obtaining a stable film, film thickness value, etc. These observations give reasons to believe that model studies can support a comprehensive understanding of how the change in polymeric surfactant structure can impact thin liquid films properties. This may enable a targeted design of the macromolecular architecture depending on the polymeric surfactants application purpose. PMID:21807358

  13. 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...

  14. Blinking statistics of a molecular beacon triggered by end-denaturation of DNA

    International Nuclear Information System (INIS)

    We use a master equation approach based on the Poland-Scheraga free energy for DNA denaturation to investigate the (un)zipping dynamics of a denaturation wedge in a stretch of DNA that is clamped at one end. In particular, we quantify the blinking dynamics of a fluorophore-quencher pair mounted within the denaturation wedge. We also study the behavioural changes in the presence of proteins that selectively bind to single-stranded DNA. We show that such a set-up could be well suited as an easy-to-implement nanodevice for sensing environmental conditions in small volumes

  15. 13C-NMR studies of membrane lipid-protein interactions upon protein heat denaturation

    International Nuclear Information System (INIS)

    Spinach chloroplast membranes were studied by natural abundance carbon-13 nuclear magnetic resonance (13C-NMR) spectroscopy in their normal state and after heat denaturation of membrane proteins. The membrane proteins were denaturated by raising the temperature of the sample to 67degC for 5 minutes. Line-broadening of 13C-NMR resonances arising from the 1st (carbonyl), 7th, 9th and 12th carbon atom of fatty-acyl chains at these locations, obviously caused by changes in interactions between membrane lipids and proteins upon heat denaturation of membrane proteins. (author). 7 refs.; 1 fig

  16. Blinking statistics of a molecular beacon triggered by end-denaturation of DNA

    OpenAIRE

    Ambjoernsson, Tobias; Metzler, Ralf

    2005-01-01

    We use a master equation approach based on the Poland-Scheraga free energy for DNA denaturation to investigate the (un)zipping dynamics of a denaturation wedge in a stretch of DNA, that is clamped at one end. In particular, we quantify the blinking dynamics of a fluorophore-quencher pair mounted within the denaturation wedge. We also study the behavioural changes in the presence of proteins, that selectively bind to single-stranded DNA. We show that such a setup could be well-suited as an eas...

  17. Denaturation processes in gamma irradiated proteins studied by differential scanning calorimetry

    International Nuclear Information System (INIS)

    Differential scanning calorimetry was applied to study the influence of gamma irradiation on the process of denaturation of proteins, occurring in water suspensions during heating. Irradiations of solid native samples and of water suspensions of the selected globular proteins were performed in air atmosphere at ambient temperature or in solid CO2, by applying 20-30 kGy, 3 kGy and 2.5 kGy doses. A decrease of peak and onset temperatures, broadening of the denaturation endothermal effects, as well as a decline in denaturation enthalpy was observed as a result of irradiation

  18. 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.

  19. Structure-property relationship of quinuclidinium surfactants--Towards multifunctional biologically active molecules.

    Science.gov (United States)

    Skočibušić, Mirjana; Odžak, Renata; Štefanić, Zoran; Križić, Ivana; Krišto, Lucija; Jović, Ozren; Hrenar, Tomica; Primožič, Ines; Jurašin, Darija

    2016-04-01

    Motivated by diverse biological and pharmacological activity of quinuclidine and oxime compounds we have synthesized and characterized novel class of surfactants, 3-hydroxyimino quinuclidinium bromides with different alkyl chains lengths (CnQNOH; n=12, 14 and 16). The incorporation of non conventional hydroxyimino quinuclidinium headgroup and variation in alkyl chain length affects hydrophilic-hydrophobic balance of surfactant molecule and thereby physicochemical properties important for its application. Therefore, newly synthesized surfactants were characterized by the combination of different experimental techniques: X-ray analysis, potentiometry, electrical conductivity, surface tension and dynamic light scattering measurements, as well as antimicrobial susceptibility tests. Comprehensive investigation of CnQNOH surfactants enabled insight into structure-property relationship i.e., way in which the arrangement of surfactant molecules in the crystal phase correlates with their solution behavior and biologically activity. The synthesized CnQNOH surfactants exhibited high adsorption efficiency and relatively low critical micelle concentrations. In addition, all investigated compounds showed very potent and promising activity against Gram-positive and clinically relevant Gram-negative bacterial strains compared to conventional antimicrobial agents: tetracycline and gentamicin. The overall results indicate that bicyclic headgroup with oxime moiety, which affects both hydrophilicity and hydrophobicity of CnQNOH molecule in addition to enabling hydrogen bonding, has dominant effect on crystal packing and physicochemical properties. The unique structural features of cationic surfactants with hydroxyimino quinuclidine headgroup along with diverse biological activity have made them promising structures in novel drug discovery. Obtained fundamental understanding how combination of different functionalities in a single surfactant molecule affects its physicochemical

  20. MINERAL-SURFACTANT INTERACTIONS FOR MINIMUM REAGENTS PRECIPITATION AND ADSORPTION FOR IMPROVED OIL RECOVERY

    Energy Technology Data Exchange (ETDEWEB)

    P. Somasundaran

    2005-04-30

    The aim of this project is to delineate the role of mineralogy of reservoir rocks in determining interactions between reservoir minerals and externally added reagents (surfactants/polymers) and its effect on critical solid-liquid and liquid-liquid interfacial properties such as adsorption, wettability and interfacial tension in systems relevant to reservoir conditions. Previous studies have suggested that significant surfactant loss by precipitation or adsorption on reservoir minerals can cause chemical schemes to be less than satisfactory for enhanced oil recovery. Both macroscopic adsorption, wettability and microscopic orientation and conformation studies for various surfactant/polymer mixtures/reservoir rocks systems were conducted to explore the cause of chemical loss by means of precipitation or adsorption, and the effect of rock mineralogy on the chemical loss. During this period, the adsorption of mixed system of n-dodecyl-{beta}-D-maltoside (DM) and dodecyl sulfonate (C{sub 12}SO{sub 3}Na) has been studied. The effects of solution pH, surfactant mixing ratio and different salts on surfactant adsorption on alumina have been investigated in detail. Along with these adsorption studies, changes in mineral wettability due to the adsorption of the mixtures were determined under relevant conditions to identify the nano-structure of the adsorbed layers. Solution properties of C{sub 12}SO{sub 3}Na/DM mixtures were also studied to identify surfactant interactions that affect the mixed aggregate formation in solution. Adsorption of SDS on gypsum and limestone suggested stronger surfactant/mineral interaction than on alumina, due to the precipitation of surfactant by dissolved calcium ions. The effects of different salts such as sodium nitrate, sodium sulfite and sodium chloride on DM adsorption on alumina have also been determined. As surfactant hemimicelles at interface and micelles in solution have drastic effects on oil recovery processes, their microstructures in

  1. MINERAL-SURFACTANT INTERACTIONS FOR MINIMUM REAGENTS PRECIPITATION AND ADSORPTION FOR IMPROVED OIL RECOVERY

    International Nuclear Information System (INIS)

    The aim of this project is to delineate the role of mineralogy of reservoir rocks in determining interactions between reservoir minerals and externally added reagents (surfactants/polymers) and its effect on critical solid-liquid and liquid-liquid interfacial properties such as adsorption, wettability and interfacial tension in systems relevant to reservoir conditions. Previous studies have suggested that significant surfactant loss by precipitation or adsorption on reservoir minerals can cause chemical schemes to be less than satisfactory for enhanced oil recovery. Both macroscopic adsorption, wettability and microscopic orientation and conformation studies for various surfactant/polymer mixtures/reservoir rocks systems were conducted to explore the cause of chemical loss by means of precipitation or adsorption, and the effect of rock mineralogy on the chemical loss. During this period, the adsorption of mixed system of n-dodecyl-β-D-maltoside (DM) and dodecyl sulfonate (C12SO3Na) has been studied. The effects of solution pH, surfactant mixing ratio and different salts on surfactant adsorption on alumina have been investigated in detail. Along with these adsorption studies, changes in mineral wettability due to the adsorption of the mixtures were determined under relevant conditions to identify the nano-structure of the adsorbed layers. Solution properties of C12SO3Na/DM mixtures were also studied to identify surfactant interactions that affect the mixed aggregate formation in solution. Adsorption of SDS on gypsum and limestone suggested stronger surfactant/mineral interaction than on alumina, due to the precipitation of surfactant by dissolved calcium ions. The effects of different salts such as sodium nitrate, sodium sulfite and sodium chloride on DM adsorption on alumina have also been determined. As surfactant hemimicelles at interface and micelles in solution have drastic effects on oil recovery processes, their microstructures in solutions and at mineral

  2. Dimeric Surfactants: Promising Ingredients of Cosmetics and Toiletries

    OpenAIRE

    Naveen Kumar; Rashmi Tyagi

    2013-01-01

    Surfactants are an essential ingredient for cosmetic, toiletries and personal care products for enhancing their performance. Dimeric surfactants demonstrate superiority compared to conventional surfactants in all areas of application. Dimeric surfactants are extremely promising for utilization in various cosmetic formulations viz. shampoo, lotions, creams, conditioners etc. These surfactants possess extremely unique surface properties viz. lower surface tension, unique micellization, low crit...

  3. Interfacial behaviour of Catanionic surfactants

    OpenAIRE

    STOCCO, Antonio; David, Carriere; Maximilien, Cottat; Dominique, Langevin

    2010-01-01

    We report a dramatic increase of foam stability for catanionic mixtures (myristic acid and cetyl trimethylammonium bromide, CTABr) with respect to pristine CTABr solutions. This increase was related to the low surface tension, high surface concentration and high viscoelastic compression moduli, as measured with rising bubble experiments and ellipsometry. Dialysis of the catanionic mixtures has been used to decrease the concentration of free surfactant ions (CTA+). The equilibrium surface tens...

  4. Surfactants in tribology, v.3

    CERN Document Server

    Biresaw, Girma

    2013-01-01

    The manufacture and use of almost every consumer and industrial product rely on application of advanced knowledge in surface science and tribology. These two disciplines are of critical importance in major economic sectors, such as mining, agriculture, manufacturing (including metals, plastics, wood, computers, MEMS, NEMS, appliances), construction, transportation, and medical instruments, transplants, and diagnostic devices. An up-to-date reference with contributions by experts in surface science and tribology, Surfactants in Tribology, Volume 3 discusses some of the underlying tribological a

  5. 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%.

  6. The effect of surfactants on the instability of a rotating liquid jet

    International Nuclear Information System (INIS)

    It has long been known that the presence of surfactants on the free surface of a liquid jet can create surface tension gradients along the interface. The resulting formation of tangential stresses along the surface lead to Marangoni type flows and greatly affect the resulting dynamics of rupture. In this way surfactants can be used to manipulate the breakup of a liquid jet and control the size of droplets produced. In this paper we investigate the effects of insoluble surfactants on the breakup of rotating liquid jets with applications to industrial prilling. Using a long wavelength approximation we reduce the governing equations into a set of one-dimensional equations. We use an asymptotic theory to find steady solutions and then carry out a linear instability analysis on these solutions. We show that steady state centreline solutions are independent of viscosity to leading order and that the most unstable wavenumber and growth rate of disturbances decrease as the effectiveness of surfactants is increased. We also numerically solve these equations using a finite difference scheme to investigate the effects of changing the initial surfactant concentration and other fluid parameters. Our results show that differences in breakup lengths between rotating surfactant-laden jets and surfactant-free jets increase with the rate of rotation. Moreover, we find that satellite droplet sizes decrease as the rate of rotation is decreased with the effect of surfactants amplifying the reduction in sizes. Furthermore, the presence of surfactants at fixed rotation rates is shown to produce larger main droplets at low disturbance wavenumbers whilst satellite droplets are smaller for moderate disturbance wavenumbers κ ∼ 0.7.

  7. Kinetics of Thermal Denaturation and Aggregation of Bovine Serum Albumin

    Science.gov (United States)

    Borzova, Vera A.; Markossian, Kira A.; Chebotareva, Natalia A.; Kleymenov, Sergey Yu.; Poliansky, Nikolay B.; Muranov, Konstantin O.; Stein-Margolina, Vita A.; Shubin, Vladimir V.; Markov, Denis I.; Kurganov, Boris I.

    2016-01-01

    Thermal aggregation of bovine serum albumin (BSA) has been studied using dynamic light scattering, asymmetric flow field-flow fractionation and analytical ultracentrifugation. The studies were carried out at fixed temperatures (60°C, 65°C, 70°C and 80°C) in 0.1 M phosphate buffer, pH 7.0, at BSA concentration of 1 mg/ml. Thermal denaturation of the protein was studied by differential scanning calorimetry. Analysis of the experimental data shows that at 65°C the stage of protein unfolding and individual stages of protein aggregation are markedly separated in time. This circumstance allowed us to propose the following mechanism of thermal aggregation of BSA. Protein unfolding results in the formation of two forms of the non-native protein with different propensity to aggregation. One of the forms (highly reactive unfolded form, Uhr) is characterized by a high rate of aggregation. Aggregation of Uhr leads to the formation of primary aggregates with the hydrodynamic radius (Rh,1) of 10.3 nm. The second form (low reactive unfolded form, Ulr) participates in the aggregation process by its attachment to the primary aggregates produced by the Uhr form and possesses ability for self-aggregation with formation of stable small-sized aggregates (Ast). At complete exhaustion of Ulr, secondary aggregates with the hydrodynamic radius (Rh,2) of 12.8 nm are formed. At 60°C the rates of unfolding and aggregation are commensurate, at 70°C the rates of formation of the primary and secondary aggregates are commensurate, at 80°C the registration of the initial stages of aggregation is complicated by formation of large-sized aggregates. PMID:27101281

  8. Alterations of alveolar type II cells and intraalveolar surfactant after bronchoalveolar lavage and perfluorocarbon ventilation. An electron microscopical and stereological study in the rat lung

    OpenAIRE

    Burkhardt Wolfram; Köthe Lars; Wendt Sebastian; Rüdiger Mario; Wauer Roland R; Ochs Matthias

    2007-01-01

    Abstract Background Repeated bronchoalveolar lavage (BAL) has been used in animals to induce surfactant depletion and to study therapeutical interventions of subsequent respiratory insufficiency. Intratracheal administration of surface active agents such as perfluorocarbons (PFC) can prevent the alveolar collapse in surfactant depleted lungs. However, it is not known how BAL or subsequent PFC administration affect the intracellular and intraalveolar surfactant pool. Methods Male wistar rats w...

  9. Alterations of alveolar type II cells and intraalveolar surfactant after bronchoalveolar lavage and perfluorocarbon ventilation; an electron microscopical and stereological study in the rat lung ; Research

    OpenAIRE

    Rüdiger, Mario; Wendt, Sebastian; Köthe, Lars; Burkhardt, Wolfram; Wauer, Roland R.; Ochs, Matthias

    2007-01-01

    Background: Repeated bronchoalveolar lavage (BAL) has been used in animals to induce surfactant depletion and to study therapeutical interventions of subsequent respiratory insufficiency. Intratracheal administration of surface active agents such as perfluorocarbons (PFC) can prevent the alveolar collapse in surfactant depleted lungs. However, it is not known how BAL or subsequent PFC administration affect the intracellular and intraalveolar surfactant pool. Methods: Male wistar rats were sur...

  10. Bacterial degradation of emulsified crude oil and the effects of various surfactants

    International Nuclear Information System (INIS)

    The effects of surfactants on the oxidation rate of alkanes in crude oil were investigated using a selected bacterial species, Rhodococcus sp., pregrown to various growth stages. Oxidation rates were measured in a three-hour period by Warburg respirometry. Response to emulsified oil was found to be dependent on the physiological state of the bacteria. In the exponential growth phase oxidation rates were negatively affected by surfactant amendment, whereas in the stationary growth phase oxidation rates appear to have been stimulated. The stimulatory effect was attributed to the chemical structure and physico-chemical properties of the surfactants. Surfactants with hydrophilic-lipophilic balance values (HLB) in the intermediate range of 8-12 gave the best values. Neither the commercial dispersants nor the biosurfactants exhibited any stimulative effects. 21 refs., 4 tabs., 1 fig

  11. Self-aggregation and liquid crystalline behavior of new ester-functionalized quinuclidinolium surfactants.

    Science.gov (United States)

    Bhadani, Avinash; Endo, Takeshi; Koura, Setsuko; Sakai, Kenichi; Abe, Masahiko; Sakai, Hideki

    2014-08-01

    A new type of ester-based cationic surfactant having a quinuclidinolium headgroup has been synthesized starting from linear fatty alcohols and has been characterized using spectroscopic techniques. The self-aggregation and thermodynamic properties of these surfactants have been investigated by pendant-drop surface tensiometry and conductivity measurements. The liquid crystalline behaviors of these surfactants were investigated by small-angle X-ray scattering (SAXS) technique. The quinuclidinolium headgroup demonstrated a unique ability to interlock among themselves thus affecting the physicochemical properties of surfactants in aqueous solution. The current research finding supports the new concept of headgroup interlocking which is supported by 1D and 2D NMR studies. PMID:25058797

  12. Cytotoxicity of single-walled carbon nanotubes suspended in various surfactants

    Energy Technology Data Exchange (ETDEWEB)

    Dong Lifeng [Department of Physics, Astronomy, and Materials Science, Missouri State University, Springfield, MO 65897 (United States); Joseph, Katherine L; Witkowski, Colette M; Craig, Michael M [Department of Biomedical Sciences, Missouri State University, Springfield, MO 65897 (United States)], E-mail: LifengDong@MissouriState.edu

    2008-06-25

    The cytotoxicity of single-walled carbon nanotubes (SWCNTs) suspended in various surfactants was investigated by phase contrast light microscopy characterization in combination with an absorbance spectroscopy cytotoxicity analysis. Our data indicate that individual SWCNTs suspended in the surfactants, sodium dodecyl sulfate (SDS) and sodium dodecylbenzene sulfonate (SDBS), were toxic to 1321N1 human astrocytoma cells due to the toxicity of SDS and SDBS on the nanotube surfaces. This toxicity was observed when cells were exposed to an SDS or SDBS solution having a concentration as low as 0.05 mg ml{sup -1} for 30 min. The proliferation and viability of the cells were not affected by SWCNTs alone or by conjugates of SWCNTs with various concentrations of sodium cholate (SC) or single-stranded DNA. The cells proliferated similarly to untreated cells when surrounded by SWCNTs as they grow, which indicated that the nanotubes did not affect cells adversely. The cytotoxicity of the nanotube-surfactant conjugates was controlled in these experiments by the toxicity of the surfactants. Consequently, when evaluating a surfactant to be used for the dispersion of nanoscale materials in applications such as nanoscale electronics or non-viral biomolecular transporters, the cytotoxicity needs to be evaluated. The methodology proposed in this study can be used to investigate the cytotoxicity of other nanoscale materials suspended in a variety of surfactants.

  13. 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.

  14. Thermal denaturation of egg protein under nanosecond pulsed laser heating of gold nanoparticles

    International Nuclear Information System (INIS)

    Thermal denaturation of egg protein in the presence of gold nanoparticles via their heating at the plasmon resonance wavelength by the pulsed radiation of the second harmonic of an Nd:YAG laser (532 nm) is investigated. The experimental dependence of the protein denaturation time on the mean laser power is obtained. The heating temperature of the medium with gold nanoparticles is calculated. The numerical estimates of the temperature of the heated medium containing protein and gold nanoparticles (45.3 deg. C at the moment of protein denaturation) are in good agreement with the literature data on its thermal denaturation and with the data of pyrometric measurements (42.0 ± 1.5 deg. C). The egg protein may be successfully used to investigate the specific features of laser heating of proteins in the presence of metal nanoparticles under their excitation at the plasmon resonance wavelength. (laser methods in biology)

  15. A fully atomistic computer simulation study of cold denaturation of a β-hairpin

    Science.gov (United States)

    Yang, Changwon; Jang, Soonmin; Pak, Youngshang

    2014-12-01

    Cold denaturation is a fundamental phenomenon in aqueous solutions where the native structure of proteins disrupts on cooling. Understanding this process in molecular details can provide a new insight into the detailed natures of hydrophobic forces governing the stability of proteins in water. We show that the cold-denaturation-like phenomenon can be directly observed at low temperatures using a fully atomistic molecular dynamics simulation method. Using a highly optimized protein force field in conjunction with three different explicit water models, a replica exchange molecular dynamics simulation scheme at constant pressures allows for the computation of the melting profile of an experimentally well-characterized β-hairpin peptide. For all three water models tested, the simulated melting profiles are indicative of possible cold denaturation. From the analysis of simulation ensembles, we find that the most probable cold-denatured structure is structurally compact, with its hydrogen bonds and native hydrophobic packing substantially disrupted.

  16. Stabilizing effect of biochar on soil extracellular enzymes after a denaturing stress

    Science.gov (United States)

    Stabilization of extracellular enzymes may maintain enzymatic activity for ecosystem services such as carbon sequestration, nutrient cycling, and bioremediation, while protecting enzymes from proteolysis and denaturation. A laboratory incubation study was conducted to determine whether a fast pyroly...

  17. Protein denaturation of whey protein isolates (WPIs) induced by high intensity ultrasound during heat gelation.

    Science.gov (United States)

    Frydenberg, Rikke P; Hammershøj, Marianne; Andersen, Ulf; Greve, Marie T; Wiking, Lars

    2016-02-01

    In this study, the impact of high intensity ultrasound (HIU) on proteins in whey protein isolates was examined. Effects on thermal behavior, secondary structure and nature of intra- and intermolecular bonds during heat-induced gelling were investigated. Ultrasonication (24 kHz, 300 W/cm(2), 2078 J/mL) significantly reduced denaturation enthalpies, whereas no change in secondary structure was detected by circular dichroism. The thiol-blocking agent N-ethylmaleimide was applied in order to inhibit formation of disulfide bonds during gel formation. Results showed that increased contents of α-lactalbumin (α-La) were associated with increased sensitivity to ultrasonication. The α-La:β-lactoglobulin (β-Lg) ratio greatly affected the nature of the interactions formed during gelation, where higher amounts of α-La lead to a gel more dependent on disulfide bonds. These results contribute to clarifying the mechanisms mediating the effects of HIU on whey proteins on the molecular level, thus moving further toward implementing HIU in the processing chain in the food industry. PMID:26304368

  18. Exogenous pulmonary surfactant as a drug delivering agent: influence of antibiotics on surfactant activity.

    OpenAIRE

    van 't Veen, A; Gommers, D.; Mouton, J. W.; Kluytmans, J.A.; Krijt, E. J.; Lachmann, B.

    1996-01-01

    1. It has been proposed to use exogenous pulmonary surfactant as a drug delivery system for antibiotics to the alveolar compartment of the lung. Little, however, is known about interactions between pulmonary surfactant and antimicrobial agents. This study investigated the activity of a bovine pulmonary surfactant after mixture with amphotericin B, amoxicillin, ceftazidime, pentamidine or tobramycin. 2. Surfactant (1 mg ml-1 in vitro and 40 mg ml-1 in vivo) was mixed with 0.375 mg ml-1 amphote...

  19. Synthetic pulmonary surfactant : Effects of surfactant proteins B and C and their analogues

    OpenAIRE

    Almlén, Andreas

    2010-01-01

    Pulmonary surfactant is a lipid/protein mixture lining the air-liquid interface in the alveoli. Its main function is to lower surface tension during respiration and thereby prevent alveolar collapse at end-expiration. Surfactant deficiency, especially common in prematurely born babies, is the main cause of respiratory distress syndrome (RDS). This disease is treated with exogenous surfactant replacement using animal-derived modified natural surfactants. Production of these i...

  20. Surfactant inhibition in acute respiratory failure : consequences for exogenous surfactant therapy

    OpenAIRE

    Eijking, Eric

    1993-01-01

    textabstractThe neonatal respiratory distress syndrome (RDS) is characterized by immaturity of the lung, resulting in relative or absolute absence of pulmonary surfactant. Worldwide, neonates suffering from RDS have been treated successfully with exogenous surfactant preparations. Currently, exogenous surfactant administration has been accepted as a valuable treatment for this syndrome. Nevertheless, many questions on exogenous surfactant treatment remain unanswered. It has been observed that...

  1. The Biophysical Function of Pulmonary Surfactant

    OpenAIRE

    Rugonyi, Sandra; Biswas, Samares C.; Hall, Stephen B.

    2008-01-01

    Pulmonary surfactant lowers surface tension in the lungs. Physiological studies indicate two key aspects of this function: that the surfactant film forms rapidly; and that when compressed by the shrinking alveolar area during exhalation, the film reduces surface tension to very low values. These observations suggest that surfactant vesicles adsorb quickly, and that during compression, the adsorbed film resists the tendency to collapse from the interface to form a three-dimensional bulk phase....

  2. Surfactant-Templated Mesoporous Metal Oxide Nanowires

    OpenAIRE

    Hongmei Luo; Qianglu Lin; Stacy Baber; Mahesh Naalla

    2010-01-01

    We demonstrate two approaches to prepare mesoporous metal oxide nanowires by surfactant assembly and nanoconfinement via sol-gel or electrochemical deposition. For example, mesoporous Ta2O5 and zeolite nanowires are prepared by block copolymer Pluronic 123-templated sol-gel method, and mesoporous ZnO nanowires are prepared by electrodeposition in presence of anionic surfactant sodium dodecyl sulfate (SDS) surfactant, in porous membranes. The morphologies of porous nanowires are studied by sca...

  3. A route to simple nonionic surfactants

    Directory of Open Access Journals (Sweden)

    Sindija Brica

    2016-12-01

    Full Text Available A method for the synthesis of nonionic surfactants – N-alkyl-O-(2-hydroxyethyl carbamates is proposed by acylation of fatty amines with ethylene carbonate without any solvent or catalyst. The surface tension of the prepared surfactants was measured, toxicity and biodegradability were determined for the surfactant with n-dodecyl as a hydrophobic group and N-monosubstituted amide and hydroxyl groups for their hydrophilic part.

  4. Nonionic and ionic surfactants at an interface

    OpenAIRE

    Onuki, Akira

    2008-01-01

    A Ginzburg-Landau theory is presented on surfactants in polar binary mixtures, which aggregate at an interface due to the amphiphilic interaction. They can be ionic surfactants coexisting with counterions. Including the solvation and image interactions and accounting for a finite volume fraction of the surfactant, we obtain their distributions and the electric potential around an interface in equilibrium. The surface tension is also calculated. The distribution of the adsorbed ionic surfactan...

  5. Using dissipative particle dynamics for modeling surfactants

    OpenAIRE

    ZHANG, YUCHEN; Ardekani, Arezoo M.

    2015-01-01

    Oil recovery is an industrial process that injects aqueous solutions into an oil reservoir to pump out crude oil and promote the oil production. The aqueous solution contains surfactants for reducing the interfacial tension (IFT) between aqueous phase and oil. The critical micelle concentration (CMC) is the concentration of surfactant above which micelles form and the interfacial tension reaches a plateau. Our research seeks to measure IFT and CMC for surfactants using dissipative particle dy...

  6. Lung surfactant in subacute pulmonary disease

    OpenAIRE

    Spragg Roger G; Devendra Gehan

    2002-01-01

    Abstract Pulmonary surfactant is a surface active material composed of both lipids and proteins that is produced by alveolar type II pneumocytes. Abnormalities of surfactant in the immature lung or in the acutely inflamed mature lung are well described. However, in a variety of subacute diseases of the mature lung, abnormalities of lung surfactant may also be of importance. These diseases include chronic obstructive pulmonary disease, asthma, cystic fibrosis, interstitial lung disease, pneumo...

  7. Surfactant use outside the tertiary care centre

    OpenAIRE

    Stuart, Shelagh; McMillan, Doug

    2005-01-01

    Early administration of surfactant to preterm babies with respiratory distress syndrome saves lives and decreases morbidity such as pneumothorax. Surfactant administration shortly after birth to intubated babies less than 30 weeks gestation decreases pulmonary air leak, chronic lung disease and mortality. Some preterm babies may be born in hospitals with a transport team hours away. Surfactant administration may cause transient bradycardia or hypoxemia and may rapidly improve lung function. A...

  8. Micro-CT Imaging of Denatured Chitin by Silver to Explore Honey Bee and Insect Pathologies

    OpenAIRE

    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 ...

  9. Fouling of Heat Transfer Surfaces Related to beta-Lactoglobulin Denaturation During Heat Processing of Milk.

    Science.gov (United States)

    Lalande, M; Tissier, J P

    1985-06-01

    Denaturation of beta-lactoglobulin during heating of milk in a plate heat exchanger has been investigated as an important factor in fouling the heat transfer surface. Using, on one hand, data on chemical composition of deposits obtained from biochemical analysis technics and, on the other hand, kinetic data of beta-Iactoglobulin denaturation, the distribution profile of deposits along the surface and the experimental fouling curves can be adequately predicted. PMID:20568150

  10. Determination of microbial genome sizes by two-dimensional denaturing gradient gel electrophoresis.

    OpenAIRE

    Poddar, S K; Maniloff, J

    1989-01-01

    In two-dimensional denaturing gradient gel electrophoresis, DNA is digested with a restriction endonuclease and the resulting DNA fragments are separated as a function of size by conventional agarose gel electrophoresis. Following this first dimension electrophoresis, the fragment distribution is placed at the top of a denaturing gradient slab gel and electrophoresis is carried out parallel to the gradient direction. This second dimension separation is a complex function of the base sequence ...

  11. Constant denaturant gel electrophoresis as a rapid screening technique for p53 mutations.

    OpenAIRE

    Børresen, A.L.; Hovig, E; Smith-Sørensen, B; Malkin, D; Lystad, S; Andersen, T.I.; Nesland, J. M.; Isselbacher, K J; Friend, S H

    1991-01-01

    At present, mutation of the p53 gene appears to be the most common genetic alteration found in human cancers. These mutations can occur within many different regions of the gene. We have developed a modification of denaturing gradient gel electrophoresis termed "constant denaturant gel electrophoresis" (CDGE), which provides a rapid and sensitive method to screen the four conserved regions within the p53 gene where the majority of p53 mutations have been reported. The sensitivity of CDGE was ...

  12. Identification of the multiple beta-thalassemia mutations by denaturing gradient gel electrophoresis.

    OpenAIRE

    Cai, S P; Kan, Y W

    1990-01-01

    We used denaturing gradient gel electrophoresis to detect the beta-thalassemia mutations in the Chinese population. By amplifying the beta-globin gene in four separate fragments and electrophoresing the amplified DNA in two gels, we were able to distinguish all the 12 known mutations on the basis of the mobility of the homoduplexes and heteroduplexes. We conclude that denaturing gradient gel electrophoresis offers a nonradioactive means of detecting multiple mutations in genetic disorders.

  13. Differences in the processes of beta-lactoglobulin cold and heat denaturations.

    OpenAIRE

    Griko YuV; Kutyshenko, V. P.

    1994-01-01

    The changes in beta-lactoglobulin upon cold and heat denaturation were studied by scanning calorimetry, CD, and NMR spectroscopy. It is shown that, in the presence of urea, these processes of beta-lactoglobulin denaturation below and above 308 K are accompanied by different structural and thermodynamic changes. Analysis of the NOE spectra of beta-lactoglobulin shows that changes in the spin diffusion of beta-lactoglobulin after disruption of the unique tertiary structure upon cold denaturatio...

  14. Radioprotective Thiolamines WR-1065 and WR-33278 Selectively Denature Nonhistone Nuclear Proteins

    Science.gov (United States)

    Booth, Valerie K.; Roberts, Jeanette C.; Warters, Raymond L.; Wilmore, Britta H.; Lepock, James R.

    2000-01-01

    Differential scanning calorimetry was used to study the interactions of nuclei isolated from Chinese hamster V79 cells with the radioprotector WR-1065, other thiol compounds, and polyamines. Differential scanning calorimetry monitors denaturation of macromolecules and resolves the major nuclear components (e.g. constrained and relaxed DNA, nucleosome core, and nuclear matrix) of intact nuclei on the basis of thermal stability. WR-1065 treatment (0.5-10 mM) of isolated nuclei led to the irreversible denaturation of nuclear proteins, a fraction of which are nuclear matrix proteins. Denaturation of 50% of the total nonhistone nuclear protein content of isolated nuclei occurred after exposure to 4.7 mM WR-1065 for 20 min at 23 C. In addition, a 22% increase in the insoluble protein content of nuclei isolated from V79 cells that had been treated with 4 mM WR-1065 for 30 min at 37 C was observed, indicating that WR-1065-induced protein denaturation occurs not only in isolated nuclei but also in the nuclei of intact cells. From the extent of the increase in insoluble protein in the nucleus, protein denaturation by WR-1065 is expected to contribute to drug toxicity at concentrations greater than approximately 4 mM. WR-33278, the disulfide form of WR1065, was approximately twice as effective as the free thiol at denaturing nuclear proteins. The proposed mechanism for nucleoprotein denaturation is through direct interactions with protein cysteine groups with the formation of destabilizing protein-WR-1065 disulfides. In comparison to its effect on nuclear proteins in isolated nuclei, WR-1065 had only a very small effect on non-nuclear proteins of whole cells, isolated nuclear matrix, or the thiol-rich Ca (2+) ATPase of sarcoplasmic reticulum, indicating that WR-1065 can effectively denature protein only inside an intact nucleus, probably due to the increased concentration of the positively charged drug in the vicinity of DNA.

  15. Observation of Solvent Penetration during Cold Denaturation of E. coli Phosphofructokinase-2

    OpenAIRE

    Ramírez-Sarmiento, César A.; Baez, Mauricio; Wilson, Christian A.M.; Babul, Jorge; Komives, Elizabeth A.; Guixé, Victoria

    2013-01-01

    Phosphofructokinase-2 is a dimeric enzyme that undergoes cold denaturation following a highly cooperative N2 2I mechanism with dimer dissociation and formation of an expanded monomeric intermediate. Here, we use intrinsic fluorescence of a tryptophan located at the dimer interface to show that dimer dissociation occurs slowly, over several hours. We then use hydrogen-deuterium exchange mass spectrometry experiments, performed by taking time points over the cold denaturation process, to measur...

  16. Electrospray mass spectrometry as a method for studying the high pressure denaturation of proteins

    OpenAIRE

    Stefanowicz, Piotr; Petry-Podgorska, Inga; Kowalewska, Karolina; Jaremko, Lukasz; Jaremko, Mariusz; Szewczuk, Zbigniew

    2009-01-01

    Abstract High pressure denaturation of proteins can provide important information concerning their folding and function. These studies require expensive and complicated equipment. In this paper we present a new convenient method for studying high-pressure denaturation of proteins combining deuterium-hydrogen exchange and electrospray mass spectrometry. Application of various values of pressure causes different degrees of protein unfolding resulting in molecules with a different num...

  17. Pretransitional structural changes in the thermal denaturation of ribonuclease S and S protein.

    OpenAIRE

    Stelea, Simona D.; Keiderling, Timothy A.

    2002-01-01

    Two mechanisms have been proposed for the thermal unfolding of ribonuclease S (RNase S). The first is a sequential partial unfolding of the S peptide/S protein complex followed by dissociation, whereas the second is a concerted denaturation/dissociation. The thermal denaturation of ribonuclease S and its fragment, the S protein, were followed with circular dichroism and infrared spectra. These spectra were analyzed by the principal component method of factor analysis. The use of multiple spec...

  18. Test of cold denaturation mechanism for proteins as a function of water's structure

    OpenAIRE

    Marques, Manuel I.

    2006-01-01

    In a recent paper [PRL 91, 138103 (2003)] a new mechanism to explain the cold denaturation of proteins, based on the loss of local low-density water structure, has been proposed. In the present paper this mechanism is tested by means of full atom numerical simulations. In good agreement with this proposal, cold denaturation resulting in the unfolded state was found at the High Density Liquid (HDL) state of water, at which the amount of open tetragonal hydrogen bonds decreases at cooling.

  19. Protein-mediated Loops and Phase Transition in Nonthermal Denaturation of DNA

    OpenAIRE

    Petrosyan, K. G.; Hu, Chin-Kun

    2009-01-01

    We use a statistical mechanical model to study nonthermal denaturation of DNA in the presence of protein-mediated loops. We find that looping proteins which randomly link DNA bases located at a distance along the chain could cause a first-order phase transition. We estimate the denaturation transition time near the phase transition, which can be compared with experimental data. The model describes the formation of multiple loops via dynamical (fluctuational) linking between looping proteins, ...

  20. Thermal Denaturation and Aggregation of Myosin Subfragment 1 Isoforms with Different Essential Light Chains

    OpenAIRE

    Zubov, Eugene O.; Nikolaeva, Olga P.; Kurganov, Boris I.; Dmitrii I. Levitsky; Markov, Denis I.

    2010-01-01

    We compared thermally induced denaturation and aggregation of two isoforms of the isolated myosin head (myosin subfragment 1, S1) containing different “essential” (or “alkali”) light chains, A1 or A2. We applied differential scanning calorimetry (DSC) to investigate the domain structure of these two S1 isoforms. For this purpose, a special calorimetric approach was developed to analyze the DSC profiles of irreversibly denaturing multidomain proteins. Using this approach, we revealed two calor...

  1. Effects of moderate electric fields (MEF) on denaturation of whey proteins solutions

    OpenAIRE

    Pereira, Ricardo; Teixeira, J. A.; Vicente, A.A.

    2012-01-01

    Electric fields application during thermal processing are now receiving increased attention due to uniform heating of liquids and extremely rapid heating rates, which presumably enables higher temperatures to be applied without inducing excessive denaturation of the constituent proteins [1]. The aim of this work was to evaluate the effects of moderate electric fields (MEF) on denaturation kinetics and thermodynamic properties of whey protein dispersions at temperatures ranging from 75 to 90 º...

  2. A possible mechanism for cold denaturation of proteins at high pressure

    OpenAIRE

    Marques, Manuel I.; Borreguero, Jose M.; Stanley, H. Eugene; Dokholyan, Nikolay V.

    2002-01-01

    We study cold denaturation of proteins at high pressures. Using multicanonical Monte Carlo simulations of a model protein in a water bath, we investigate the effect of water density fluctuations on protein stability. We find that above the pressure where water freezes to the dense ice phase ($\\approx2$ kbar), the mechanism for cold denaturation with decreasing temperature is the loss of local low-density water structure. We find our results in agreement with data of bovine pancreatic ribonucl...

  3. The specificity of albumin denaturation on physiological preparations under thermal and gamma-radiation effects (actions)

    International Nuclear Information System (INIS)

    Comparative investigation is performed of the alteration in thin structure of absorption spectra of albumin solutions under thermal and radiation effect resulting in protein denaturation. Gamma radiation effect of 57Co on the preparations of bull and man serum albumins was studied as well as a number of serum preparations. Analysis of the results obtained permits to conclude that different qualitative and quantitative mechanisms of denaturation alterations under the temperature and gamma radiation effects on albumin solutions takes place

  4. Mean-squared atomic displacements in hydrated lysozyme, native and denatured

    OpenAIRE

    Mamontov, Eugene; O’Neill, Hugh; Zhang, Qiu

    2010-01-01

    We use elastic neutron scattering to demonstrate that a sharp increase in the mean-squared atomic displacements, commonly observed in hydrated proteins above 200 K and often referred to as the dynamical transition, is present in the hydrated state of both native and denatured lysozyme. A direct comparison of the native and denatured protein thus confirms that the presence of the transition in the mean-squared atomic displacements is not specific to biologically functional molecules.

  5. Solubilization of Hydrophobic Dyes in Surfactant Solutions

    Directory of Open Access Journals (Sweden)

    Ali Reza Tehrani-Bagha

    2013-02-01

    Full Text Available In this paper, the use of surfactants for solubilization of hydrophobic organic dyes (mainly solvent and disperse dyes has been reviewed. The effect of parameters such as the chemical structures of the surfactant and the dye, addition of salt and of polyelectrolytes, pH, and temperature on dye solubilization has been discussed. Surfactant self-assemble into micelles in aqueous solution and below the concentration where this occurs—the critical micelle concentration (CMC—there is no solubilization. Above the CMC, the amount of solubilized dye increases linearly with the increase in surfactant concentration. It is demonstrated that different surfactants work best for different dyes. In general, nonionic surfactants have higher solubilization power than anionic and cationic surfactants. It is likely that the reason for the good performance of nonionic surfactants is that they allow dyes to be accommodated not only in the inner, hydrocarbon part of the micelle but also in the headgroup shell. It is demonstrated that the location of a dye in a surfactant micelle can be assessed from the absorption spectrum of the dye-containing micellar solution.

  6. Lung surfactant in subacute pulmonary disease

    Directory of Open Access Journals (Sweden)

    Spragg Roger G

    2002-04-01

    Full Text Available Abstract Pulmonary surfactant is a surface active material composed of both lipids and proteins that is produced by alveolar type II pneumocytes. Abnormalities of surfactant in the immature lung or in the acutely inflamed mature lung are well described. However, in a variety of subacute diseases of the mature lung, abnormalities of lung surfactant may also be of importance. These diseases include chronic obstructive pulmonary disease, asthma, cystic fibrosis, interstitial lung disease, pneumonia, and alveolar proteinosis. Understanding of the mechanisms that disturb the lung surfactant system may lead to novel rational therapies for these diseases.

  7. Cholesterol-mediated surfactant dysfunction is mitigated by surfactant protein A.

    Science.gov (United States)

    Hiansen, Joshua Qua; Keating, Eleonora; Aspros, Alex; Yao, Li-Juan; Bosma, Karen J; Yamashita, Cory M; Lewis, James F; Veldhuizen, Ruud A W

    2015-03-01

    The ability of pulmonary surfactant to reduce surface tension at the alveolar surface is impaired in various lung diseases. Recent animal studies indicate that elevated levels of cholesterol within surfactant may contribute to its inhibition. It was hypothesized that elevated cholesterol levels within surfactant inhibit human surfactant biophysical function and that these effects can be reversed by surfactant protein A (SP-A). The initial experiment examined the function of surfactant from mechanically ventilated trauma patients in the presence and absence of a cholesterol sequestering agent, methyl-β-cyclodextrin. The results demonstrated improved surface activity when cholesterol was sequestered in vitro using a captive bubble surfactometer (CBS). These results were explored further by reconstitution of surfactant with various concentrations of cholesterol with and without SP-A, and testing of the functionality of these samples in vitro with the CBS and in vivo using surfactant depleted rats. Overall, the results consistently demonstrated that surfactant function was inhibited by levels of cholesterol of 10% (w/w phospholipid) but this inhibition was mitigated by the presence of SP-A. It is concluded that cholesterol-induced surfactant inhibition can actively contribute to physiological impairment of the lungs in mechanically ventilated patients and that SP-A levels may be important to maintain surfactant function in the presence of high cholesterol within surfactant. PMID:25522687

  8. Surfactant nebulisation : lung function, surfactant distribution and pulmonary blood flow distribution in lung lavaged rabbits

    NARCIS (Netherlands)

    Dijk, PH; Heikamp, A; Oetomo, SB

    1997-01-01

    Objective: Surfactant nebulisation is a promising alternative to surfactant instillation in newborns with the respiratory distress syndrome. Although less surfactant is deposited in the lung, it improves gas exchange, probably due to a superior distribution. We hypothesize that a more uniform distri

  9. 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. PMID:27434157

  10. Interim assessment of the denatured 233U fuel cycle: feasibility and nonproliferation characteristics

    International Nuclear Information System (INIS)

    A fuel cycle that employs 233U denatured with 238U 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 233U 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 233U cycles are compared to those of the conventional Pu/U cycle. In addition, several nuclear power systems that employ denatured 233U 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 233U 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

  11. 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.

  12. Random coil negative control reproduces the discrepancy between scattering and FRET measurements of denatured protein dimensions

    Science.gov (United States)

    Watkins, Herschel M.; Simon, Anna J.; Sosnick, Tobin R.; Lipman, Everett A.; Hjelm, Rex P.; Plaxco, Kevin W.

    2015-01-01

    Small-angle scattering studies generally indicate that the dimensions of unfolded single-domain proteins are independent (to within experimental uncertainty of a few percent) of denaturant concentration. In contrast, single-molecule FRET (smFRET) studies invariably suggest that protein unfolded states contract significantly as the denaturant concentration falls from high (∼6 M) to low (∼1 M). Here, we explore this discrepancy by using PEG to perform a hitherto absent negative control. This uncharged, highly hydrophilic polymer has been shown by multiple independent techniques to behave as a random coil in water, suggesting that it is unlikely to expand further on the addition of denaturant. Consistent with this observation, small-angle neutron scattering indicates that the dimensions of PEG are not significantly altered by the presence of either guanidine hydrochloride or urea. smFRET measurements on a PEG construct modified with the most commonly used FRET dye pair, however, produce denaturant-dependent changes in transfer efficiency similar to those seen for a number of unfolded proteins. Given the vastly different chemistries of PEG and unfolded proteins and the significant evidence that dye-free PEG is well-described as a denaturant-independent random coil, this similarity raises questions regarding the interpretation of smFRET data in terms of the hydrogen bond- or hydrophobically driven contraction of the unfolded state at low denaturant. PMID:25964362

  13. Thermal Denaturation and Aggregation of Myosin Subfragment 1 Isoforms with Different Essential Light Chains

    Directory of Open Access Journals (Sweden)

    Eugene O. Zubov

    2010-10-01

    Full Text Available We compared thermally induced denaturation and aggregation of two isoforms of the isolated myosin head (myosin subfragment 1, S1 containing different “essential” (or “alkali” light chains, A1 or A2. We applied differential scanning calorimetry (DSC to investigate the domain structure of these two S1 isoforms. For this purpose, a special calorimetric approach was developed to analyze the DSC profiles of irreversibly denaturing multidomain proteins. Using this approach, we revealed two calorimetric domains in  the S1 molecule, the more thermostable domain denaturing in two steps. Comparing the DSC data with temperature dependences of intrinsic fluorescence parameters and S1 ATPase inactivation, we have identified these two calorimetric domains as motor domain and regulatory domain of the myosin head, the motor domain being more thermostable. Some difference between the two S1 isoforms was only revealed by DSC in thermal denaturation of the regulatory domain. We also applied dynamic light scattering (DLS to analyze the aggregation of S1 isoforms induced by their thermal denaturation. We have found no appreciable difference between these S1 isoforms in their aggregation properties under ionic strength conditions close to those in the muscle fiber (in the presence of 100 mM KCl. Under these conditions kinetics of this process was independent of protein concentration, and the aggregation rate was limited by irreversible denaturation of the S1 motor domain.

  14. Surfactant-assisted dispersion of carbon nanotubes: mechanism of stabilization and biocompatibility of the surfactant

    International Nuclear Information System (INIS)

    Nanoparticles (NPs) are thermodynamically unstable system and tend to aggregate to reduce free energy. The aggregation property of NPs results in inhomogeneous exposure of cells to NPs resulting in variable cellular responses. Several types of surfactants are used to stabilize NP dispersions and obtain homogenous dispersions. However, the effects of these surfactants, per se, on cellular responses are not completely known. The present study investigated the application of Pluronic F68 (PF68) for obtaining stable dispersion of NPs using carbon nanotubes as model NPs. PF68-stabilized NP suspensions are stable for long durations and do not show signs of aggregation or settling during storage or after autoclaving. The polyethylene oxide blocks in PF68 provide steric hindrance between adjacent NPs leading to stable NP dispersions. Further, PF68 is biocompatible in nature and does not affect integrity of mitochondria, lysosomes, DNA, and nuclei. Also, PF68 neither induce free radical or cytokine production nor does it interfere with cellular uptake mechanisms. The results of the present study suggest that PF68-assisted dispersion of NPs produced suspensions, which are stable after autoclaving. Further, PF68 does not interfere with normal physiological functions suggesting its application in nanomedicine and nanotoxicity evaluation

  15. Molecular interactions at the hexadecane/water interface in the presence of surfactants studied with second harmonic generation

    Science.gov (United States)

    Sang, Yajun; Yang, Fangyuan; Chen, Shunli; Xu, Hongbo; Zhang, Si; Yuan, Qunhui; Gan, Wei

    2015-06-01

    It is important to investigate the influence of surfactants on structures and physical/chemical properties of oil/water interfaces. This work reports a second harmonic generation study of the adsorption of malachite green (MG) on the surfaces of oil droplets in a hexadecane/water emulsion in the presence of surfactants including sodium dodecyl sulfate, polyoxyethylene-sorbitan monooleate (Tween80), and cetyltrimethyl ammonium bromide. It is revealed that surfactants with micromolar concentrations notably influence the adsorption of MG at the oil/water interface. Both competition adsorption and charge-charge interactions played very important roles in affecting the adsorption free energy and the surface density of MG at the oil/water interface. The sensitive detection of the changing oil/water interface with the adsorption of surfactants at such low concentrations provides more information for understanding the behavior of these surfactants at the oil/water interface.

  16. Chain architecture and micellization: A mean-field coarse-grained model for poly(ethylene oxide) alkyl ether surfactants

    Energy Technology Data Exchange (ETDEWEB)

    García Daza, Fabián A.; Mackie, Allan D., E-mail: allan.mackie@urv.cat [Department d’Enginyeria Química, ETSEQ, Universitat Rovira i Virgili, Avinguda dels Països Catalans 26, 43007 Tarragona (Spain); Colville, Alexander J. [Department of Chemical Engineering, Northeastern University, 360 Huntington Avenue, Boston, Massachusetts 02115-5000 (United States)

    2015-03-21

    Microscopic modeling of surfactant systems is expected to be an important tool to describe, understand, and take full advantage of the micellization process for different molecular architectures. Here, we implement a single chain mean field theory to study the relevant equilibrium properties such as the critical micelle concentration (CMC) and aggregation number for three sets of surfactants with different geometries maintaining constant the number of hydrophobic and hydrophilic monomers. The results demonstrate the direct effect of the block organization for the surfactants under study by means of an analysis of the excess energy and entropy which can be accurately determined from the mean-field scheme. Our analysis reveals that the CMC values are sensitive to branching in the hydrophilic head part of the surfactant and can be observed in the entropy-enthalpy balance, while aggregation numbers are also affected by splitting the hydrophobic tail of the surfactant and are manifested by slight changes in the packing entropy.

  17. Chain architecture and micellization: A mean-field coarse-grained model for poly(ethylene oxide) alkyl ether surfactants

    International Nuclear Information System (INIS)

    Microscopic modeling of surfactant systems is expected to be an important tool to describe, understand, and take full advantage of the micellization process for different molecular architectures. Here, we implement a single chain mean field theory to study the relevant equilibrium properties such as the critical micelle concentration (CMC) and aggregation number for three sets of surfactants with different geometries maintaining constant the number of hydrophobic and hydrophilic monomers. The results demonstrate the direct effect of the block organization for the surfactants under study by means of an analysis of the excess energy and entropy which can be accurately determined from the mean-field scheme. Our analysis reveals that the CMC values are sensitive to branching in the hydrophilic head part of the surfactant and can be observed in the entropy-enthalpy balance, while aggregation numbers are also affected by splitting the hydrophobic tail of the surfactant and are manifested by slight changes in the packing entropy

  18. Role of the charge, carbon chain length, and content of surfactant on the skin penetration of meloxicam-loaded liposomes

    Directory of Open Access Journals (Sweden)

    Duangjit S

    2014-04-01

    Full Text Available Sureewan Duangjit,1,2 Boonnada Pamornpathomkul,1 Praneet Opanasopit,1 Theerasak Rojanarata,1 Yasuko Obata,2 Kozo Takayama,2 Tanasait Ngawhirunpat11Faculty of Pharmacy, Silpakorn University, Nakhon Pathom, Thailand; 2Department of Pharmaceutics, Hoshi University, Shinagawa-ku, Tokyo, JapanAbstract: The objective of this study was to investigate the influence of surfactant charge, surfactant carbon chain length, and surfactant content on the physicochemical characteristics (ie, vesicle size, zeta potential, elasticity, and entrapment efficiency, morphology, stability, and in vitro skin permeability of meloxicam (MX-loaded liposome. Moreover, the mechanism for the liposome-enhanced skin permeation of MX was determined by Fourier transform infrared spectroscopy and differential scanning calorimetry. The model formulation used in this study was obtained using a response surface method incorporating multivariate spline interpolation (RSM-S. Liposome formulations with varying surfactant charge (anionic, neutral, and cationic, surfactant carbon chain length (C4, C12, and C16, and surfactant content (10%, 20%, and 29% were prepared. The formulation comprising 29% cationic surfactant with a C16 chain length was found to be the optimal liposome for the transdermal delivery of MX. The skin permeation flux of the optimal formulation was 2.69-fold higher than that of a conventional liposome formulation. Our study revealed that surfactants affected the physicochemical characteristics, stability, and skin permeability of MX-loaded liposomes. These findings provide important fundamental information for the development of liposomes as transdermal drug delivery systems.Keywords: optimal liposome, optimization, transdermal drug delivery, surfactant charge, surfactant carbon chain length, surfactant content

  19. Tuning Polyelectrolyte-Surfactant Interactions: Modification of Poly(ethylenimine) with Propylene Oxide and Blocks of Ethylene Oxide.

    Science.gov (United States)

    Penfold, J; Thomas, R K; Li, P; Batchelor, S N; Tucker, I M; Burley, A W

    2016-02-01

    Significantly enhanced adsorption at the air-water interface arises in polyelectrolyte/ionic surfactant mixtures, such as poly(ethylenimine)/sodium dodecyl sulfate (PEI/SDS), down to relatively low surfactant concentrations due to a strong surface interaction between the polyelectrolyte and surfactant. In the region of charge neutralization this can result in precipitation or coacervation and give rise to undesirable properties in many applications. Ethoxylation of the PEI can avoid precipitation, but can also considerably weaken the interaction. Localization of the ethoxylation can overcome these shortcomings. Further manipulation of the polyelectrolyte-surfactant interaction can be achieved by selective ethoxylation and propoxylation of the PEI amine groups. Neutron reflectivity and surface tension data are presented here which show how the polyelectrolyte-surfactant interaction can be manipulated by tuning the PEI structure. Using deuterium labeled surfactant and polymer the neutron reflectivity measurements provide details of the surface composition and structure of the adsorbed layer. The general pattern of behavior is that at low surfactant concentrations there is enhanced surfactant adsorption due to the strong surface interaction; whereas around the region of the SDS critical micellar concentration, cmc, the surface is partially depleted of surfactant in favor bulk aggregate structures. The results presented here show how these characteristic features of the adsorption are affected by the degree of ethoxylation and propoxylation. Increasing the degree of propoxylation enhances the surfactant adsorption, whereas varying the degree of ethoxylation has a less pronounced effect. In the region of surfactant surface depletion increasing both the degree of ethoxylation and propoxylation result in an increased surface depletion. PMID:26757099

  20. Surfactant phosphatidylcholine metabolism in preterm infants studied with stable isotopes

    OpenAIRE

    Bunt, Jan Erik

    2000-01-01

    textabstractAIM OF THE STUDIES 1. To develop and use a novel method to study surfactant metabolism in preterm and older infants. (chapters 3 and 4). 2. To study endogenous surfactant synthesis in relation to prenatal glucocorticosteroids. (chapters 5 and 6). 3. To study the influence of surfactant therapy on endogenous surfactant metabolism. (chapters 7 and 8). 4. To study surfactant composition and concentration after surfactant therapy. (chapter 8).

  1. Hemolysis by surfactants--A review.

    Science.gov (United States)

    Manaargadoo-Catin, Magalie; Ali-Cherif, Anaïs; Pougnas, Jean-Luc; Perrin, Catherine

    2016-02-01

    An overview of the use of surfactants for erythrocyte lysis and their cell membrane action mechanisms is given. Erythrocyte membrane characteristics and its association with the cell cytoskeleton are presented in order to complete understanding of the erythrocyte membrane distortion. Cell homeostasis disturbances caused by surfactants might induce changes starting from shape modification to cell lysis. Two main mechanisms are hypothesized in literature which are osmotic lysis and lysis by solubilization even if the boundary between them is not clearly defined. Another specific mechanism based on the formation of membrane pores is suggested in the particular case of saponins. The lytic potency of a surfactant is related to its affinity for the membrane and the modification of the lipid membrane curvature. This is to be related to the surfactant shape defined by its hydrophobic and hydrophilic moieties but also by experimental conditions. As a consequence, prediction of the hemolytic potency of a given surfactant is challenging. Several studies are focused on the relation between surfactant erythrolytic potency and their physico-chemical parameters such as the critical micellar concentration (CMC), the hydrophile-lipophile balance (HLB), the surfactant membrane/water partition coefficient (K) or the packing parameter (P). The CMC is one of the most important factors considered even if a lytic activity cut-off effect points out that the only consideration of CMC not enough predictive. The relation K.CMC must be considered in addition to the CMC to predict the surfactant lytic capacity within the same family of non ionic surfactant. Those surfactant structure/lytic activity studies demonstrate the requirement to take into account a combination of physico-chemical parameters to understand and foresee surfactant lytic potency. PMID:26687805

  2. Structured fluids polymers, colloids, surfactants

    CERN Document Server

    Witten, Thomas A

    2010-01-01

    Over the last thirty years, the study of liquids containing polymers, surfactants, or colloidal particles has developed from a loose assembly of facts into a coherent discipline with substantial predictive power. These liquids expand our conception of what condensed matter can do. Such structured-fluid phenomena dominate the physical environment within living cells. This book teaches how to think of these fluids from a unified point of view showing the far-reaching effects ofthermal fluctuations in producing forces and motions. Keeping mathematics to a minimum, the book seeks the simplest expl

  3. Surfactant Adsorption: A Revised Physical Chemistry Lab

    Science.gov (United States)

    Bresler, Marc R.; Hagen, John P.

    2008-01-01

    Many physical chemistry lab courses include an experiment in which students measure surface tension as a function of surfactant concentration. In the traditional experiment, the data are fit to the Gibbs isotherm to determine the molar area for the surfactant, and the critical micelle concentration is used to calculate the Gibbs energy of micelle…

  4. Effect of cholesterol and amyloid-β peptide on structure and function of mixed-lipid films and pulmonary surfactant BLES: an atomic force microscopy study.

    Science.gov (United States)

    Hane, Francis; Drolle, Elizabeth; Leonenko, Zoya

    2010-12-01

    Pulmonary surfactant forms a thin molecular film inside mammalian lung alveoli and lowers the surface tension of the air/fluid interface to reduce the work of breathing. Upon compression functional surfactant forms characteristic multilayer structures, which indicate surfactant surface activity. We showed that cholesterol adversely affects both structural and surface-active properties of BLES surfactant and DPPC/DOPG lipid films. Incorporation of small concentrations of fibril-forming peptide amyloid-β 1-40 helps to counteract the distractive effect of cholesterol by improving characteristic multilayer formation that occurs upon compression. In contrast to many negative effects of amyloid-forming peptides reported earlier, we report a positive effect of amyloid-β peptide on surfactant function, which may aid in the designing of novel surfactant formulations. PMID:20493966

  5. Structural organization of surfactant aggregates in vacuo: a molecular dynamics and well-tempered metadynamics study.

    Science.gov (United States)

    Longhi, Giovanna; Fornili, Sandro L; Turco Liveri, Vincenzo

    2015-07-01

    Experimental investigations using mass spectrometry have established that surfactant molecules are able to form aggregates in the gas phase. However, there is no general consensus on the organization of these aggregates and how it depends on the aggregation number and surfactant molecular structure. In the present paper we investigate the structural organization of some surfactants in vacuo by molecular dynamics and well-tempered metadynamics simulations to widely explore the space of their possible conformations in vacuo. To study how the specific molecular features of such compounds affect their organization, we have considered as paradigmatic surfactants, the anionic single-chain sodium dodecyl sulfate (SDS), the anionic double-chain sodium bis(2-ethylhexyl) sulfosuccinate (AOT) and the zwitterionic single-chain dodecyl phosphatidyl choline (DPC) within a wide aggregation number range (from 5 to 100). We observe that for low aggregation numbers the aggregates show in vacuo the typical structure of reverse micelles, while for large aggregation numbers a variety of globular aggregates occur that are characterized by the coexistence of interlaced domains formed by the polar or ionic heads and by the alkyl chains of the surfactants. Well-tempered metadynamics simulations allows us to confirm that the structural organizations obtained after 50 ns of molecular dynamics simulations are practically the equilibrium ones. Similarities and differences of surfactant aggregates in vacuo and in apolar media are also discussed. PMID:26050747

  6. Templating route for mesostructured calcium phosphates with carboxylic acid- and amine-type surfactants.

    Science.gov (United States)

    Ikawa, Nobuaki; Hori, Hideki; Kimura, Tatsuo; Oumi, Yasunori; Sano, Tsuneji

    2008-11-18

    Mesostructured calcium phosphates constructed by ionic frameworks were synthesized using carboxylic acid- and amine-type surfactants in mixed solvent systems of ethanol and water. A lamellar mesostructured calcium phosphate was prepared using palmitic acid as an anionic surfactant, as in the case using n-alkylamines. A wormhole-like mesostructured calcium phosphate can be obtained using dicarboxyl N-lauroyl- l-glutamic acid, whose headgroup is larger than that of palmitic acid. Similar mesostructured product was obtained using 4-dodecyldiethylenetriamine with a large headgroup containing two primary amine groups. Interactions of carboxyl and primary amino groups in the surfactant molecules with inorganic species are quite important for the formation of mesostructured calcium phosphates. The Ca/P molar ratio of mesostructured calcium phosphates was strongly affected by the molecular structure of surfactants containing carboxyl and primary amino groups. Ca-rich materials can be obtained using carboxylic acid-type surfactants (Ca/P approximately 1.7) rather than amine-type surfactants (Ca/P approximately 1.0). PMID:18947246

  7. Effect of humidity on the adsorption kinetics of lung surfactant at air-water interfaces.

    Science.gov (United States)

    Zuo, Yi Y; Gitiafroz, Roya; Acosta, Edgar; Policova, Zdenka; Cox, Peter N; Hair, Michael L; Neumann, A Wilhelm

    2005-11-01

    The in vitro adsorption kinetics of lung surfactant at air-water interfaces is affected by both the composition of the surfactant preparations and the conditions under which the assessment is conducted. Relevant experimental conditions are surfactant concentration, temperature, subphase pH, electrolyte concentration, humidity, and gas composition of the atmosphere exposed to the interface. The effect of humidity on the adsorption kinetics of a therapeutic lung surfactant preparation, bovine lipid extract surfactant (BLES), was studied by measuring the dynamic surface tension (DST). Axisymmetric drop shape analysis (ADSA) was used in conjunction with three different experimental methodologies, i.e., captive bubble (CB), pendant drop (PD), and constrained sessile drop (CSD), to measure the DST. The experimental results obtained from these three methodologies show that for 100% relative humidity (RH) at 37 degrees C the rate of adsorption of BLES at an air-water interface is substantially slower than for low humidity. It is also found that there is a difference in the rate of surface tension decrease measured from the PD and CB/CSD methods. These experimental results agree well with an adsorption model that considers the combined effects of entropic force, electrostatic interaction, and gravity. These findings have implications for the development and evaluation of new formulations for surfactant replacement therapy. PMID:16262325

  8. The significance of recurrent lung opacities in neonates on surfactant treatment for respiratory distress syndrome

    Energy Technology Data Exchange (ETDEWEB)

    Odita, J.C. [Dept. of Radiology, Louisiana State Univ. Health Sciences Center, Shreveport (United States)

    2001-02-01

    Purpose. To determine the significance of recurrent opacities in chest radiographs of neonates on surfactant therapy for respiratory distress syndrome (RDS) after an initial period of improvement. Materials and methods. Serial pre- and post-surfactant chest radiographs on 94 preterm infants with RDS were analyzed and the pattern of chest radiographic response was classified as (a) clear, (b) recurrent opacities, and (c) no response. Their clinical characteristics were also recorded. Results. In 34 infants the RDS changes cleared within 3 days. 31 infants developed lung opacities within 10 days after an initial period of improvement. Twenty-nine infants failed to respond to the surfactant. The corresponding mean birth weights for the three groups were 1.74, 1.19, and 0.76 kg and the mean gestation ages 32.6, 27.7, and 25.4 weeks. The incidence of bronchopulmonary dysplasia (BPD) was highest among the slumping infants (72. % vs 50 % in no responders, P < 0.001) Conclusions. The pattern of chest radiographic response is primarily affected by gestation age and birth weight. Recurrent lung opacity after an initial positive response to surfactant therapy may be caused by such factors as edema from barotrauma and patent ductus arteriosus. Infants with intraventricular hemorrhage may demonstrate neurogenic edema. Other contributory factors include pneumonia and abnormal consumption of surfactant. Recurrent lung opacities after surfactant may be a predictor of chronic lung disease in the preterm infant. (orig.)

  9. The significance of recurrent lung opacities in neonates on surfactant treatment for respiratory distress syndrome

    International Nuclear Information System (INIS)

    Purpose. To determine the significance of recurrent opacities in chest radiographs of neonates on surfactant therapy for respiratory distress syndrome (RDS) after an initial period of improvement. Materials and methods. Serial pre- and post-surfactant chest radiographs on 94 preterm infants with RDS were analyzed and the pattern of chest radiographic response was classified as (a) clear, (b) recurrent opacities, and (c) no response. Their clinical characteristics were also recorded. Results. In 34 infants the RDS changes cleared within 3 days. 31 infants developed lung opacities within 10 days after an initial period of improvement. Twenty-nine infants failed to respond to the surfactant. The corresponding mean birth weights for the three groups were 1.74, 1.19, and 0.76 kg and the mean gestation ages 32.6, 27.7, and 25.4 weeks. The incidence of bronchopulmonary dysplasia (BPD) was highest among the slumping infants (72. % vs 50 % in no responders, P < 0.001) Conclusions. The pattern of chest radiographic response is primarily affected by gestation age and birth weight. Recurrent lung opacity after an initial positive response to surfactant therapy may be caused by such factors as edema from barotrauma and patent ductus arteriosus. Infants with intraventricular hemorrhage may demonstrate neurogenic edema. Other contributory factors include pneumonia and abnormal consumption of surfactant. Recurrent lung opacities after surfactant may be a predictor of chronic lung disease in the preterm infant. (orig.)

  10. Investigating freshwater periphyton community response to uranium with phospholipid fatty acid and denaturing gradient gel electrophoresis analyses

    International Nuclear Information System (INIS)

    Periphyton communities can be used as monitors of ecosystem health and as indicators of contamination in lotic systems. Measures of biomass, community structure, and genetic diversity were used to investigate impacts of uranium (U) exposure on periphyton. Laboratory exposures of periphyton in river water amended with 238U were performed for 5 days, followed by 2 days of U depuration in unamended river water. Productivity as measured by biomass was not affected by concentrations up to 100 μg 238U L-1. Phospholipid fatty acid (PLFA) profiles and denaturing gradient gel electrophoresis (DGGE) banding patterns revealed no changes in community or genetic structure related to U exposure. We suggest that the periphyton community as a whole was not significantly impacted by exposures of 238U up to a concentration of 100 μg L-1. These findings have significance for the assessment and prediction of U impacts on aquatic ecosystems

  11. Solubilizing and Stabilizing Proteins in Anhydrous Ionic Liquids through Formation of Protein-Polymer Surfactant Nanoconstructs.

    Science.gov (United States)

    Brogan, Alex P S; Hallett, Jason P

    2016-04-01

    Nonaqueous biocatalysis is rapidly becoming a desirable tool for chemical and fuel synthesis in both the laboratory and industry. Similarly, ionic liquids are increasingly popular anhydrous reaction media for a number of industrial processes. Consequently, the use of enzymes in ionic liquids as efficient, environment-friendly, commercial biocatalysts is highly attractive. However, issues surrounding the poor solubility and low stability of enzymes in truly anhydrous media remain a significant challenge. Here, we demonstrate for the first time that engineering the surface of a protein to yield protein-polymer surfactant nanoconstructs allows for dissolution of dry protein into dry ionic liquids. Using myoglobin as a model protein, we show that this method can deliver protein molecules with near native structure into both hydrophilic and hydrophobic anhydrous ionic liquids. Remarkably, using temperature-dependent synchrotron radiation circular dichroism spectroscopy to measure half-denaturation temperatures, our results show that protein stability increases by 55 °C in the ionic liquid as compared to aqueous solution, pushing the solution thermal denaturation beyond the boiling point of water. Therefore, the work presented herein could provide a platform for the realization of biocatalysis at high temperatures or in anhydrous solvent systems. PMID:26976718

  12. Manufacture of a weakly denatured collagen fiber scaffold with excellent biocompatibility and space maintenance ability

    International Nuclear Information System (INIS)

    Although collagen scaffolds have been used for regenerative medicine, they have insufficient mechanical strength. We made a weakly denatured collagen fiber scaffold from a collagen fiber suspension (physiological pH 7.4) through a process of freeze drying and denaturation with heat under low pressure (1 × 10−1 Pa). Heat treatment formed cross-links between the collagen fibers, providing the scaffold with sufficient mechanical strength to maintain the space for tissue regeneration in vivo. The scaffold was embedded under the back skin of a rat, and biocompatibility and space maintenance ability were examined after 2 weeks. These were evaluated by using the ratio of foreign body giant cells and thickness of the residual scaffold. A weakly denatured collagen fiber scaffold with moderate biocompatibility and space maintenance ability was made by freezing at −10 °C, followed by denaturation at 140 °C for 6 h. In addition, the direction of the collagen fibers in the scaffold was adjusted by cooling the suspension only from the bottom of the container. This process increased the ratio of cells that infiltrated into the scaffold. A weakly denatured collagen fiber scaffold thus made can be used for tissue regeneration or delivery of cells or proteins to a target site. (paper)

  13. 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. PMID:25660851

  14. Rotational diffusion of bovine serum albumin denaturated by sodium dodecylsulfate, According to data from tryptophan fluorescence

    Science.gov (United States)

    Vlasova, I. M.; Zhuravleva, V. V.; Saletskii, A. M.

    2014-03-01

    The rotational diffusion of bovine serum albumin (BSA) molecules in solutions with different concentrations of the anionic detergent sodium dodecylsulfate (SDS) at different pH values is investigated, yielding information on the denaturation of BSA under the action of SDS. It is found from the increased degree of polarization in the tryptophan fluorescence of BSA and the registered parameters for the rotational diffusion of BSA molecules that the denaturation of BSA under the action of SDS at pH values less than the isoelectric point (pI) of BSA (4-9) is a two-stage process. It is shown that the first stage of BSA denaturation common for all pH values is the decondensation of BSA globules, while the second stage of BSA denaturation at pH greater than the pI of BSA is the unfolding of the protein's amino acid chain. It is concluded that the denaturation of BSA under the action of SDS proceeds more deeply at pH values greater than the pI of BSA.

  15. Spectral-luminescence and magnetic-relaxation properties of lanthanide-n-sulfonatothiacalix[4]arenes in aqueous surfactant solutions

    International Nuclear Information System (INIS)

    Influence of nonionic, anionic and cationic surfactants on magnetic-relaxation and luminescent properties of gadolinium(III), terbium(III) and dysprosium(III) complexes with n-sulfonatothiacalix[4]arene (TCAS) was studied. The nonionic and anionic surfactants do not affect the magnetic-relaxation characteristics of GdTCAS complex and luminescence intensity of complexes TbTCAS and DyTCAS. The presence of cationic surfactants at concentrations below the critical micelle formation concentration entails the formation of associates of stoichiometric composition with Tb (Dy, Gd) complexes with TCAS. The associates mentioned feature a more intense luminescence than initial complexes TbTCAS and DyTCAS

  16. Differential Denaturation of Serum Proteome Reveals a Significant Amount of Hidden Information in Complex Mixtures of Proteins

    OpenAIRE

    Verdoliva, Vincenzo; Senatore, Cinzia; Polci, Maria Letizia; Rossi, Stefania; Cordella, Martina; Carlucci, Giuseppe; Marchetti, Paolo; Antonini-Cappellini, Giancarlo; Facchiano, Antonio; D'Arcangelo, Daniela; Facchiano, Francesco

    2013-01-01

    Recently developed proteomic technologies allow to profile thousands of proteins within a high-throughput approach towards biomarker discovery, although results are not as satisfactory as expected. In the present study we demonstrate that serum proteome denaturation is a key underestimated feature; in fact, a new differential denaturation protocol better discriminates serum proteins according to their electrophoretic mobility as compared to single-denaturation protocols. Sixty nine different ...

  17. Hyperthermophile Protein Behavior: Partially-Structured Conformations of Pyrococcus furiosus Rubredoxin Monomers Generated through Forced Cold-Denaturation and Refolding

    OpenAIRE

    Chandrayan, Sanjeev Kumar; Prakash, Satya; Ahmed, Shubbir; Guptasarma, Purnananda

    2014-01-01

    Some years ago, we showed that thermo-chemically denatured, partially-unfolded forms of Pyrococcus furiosus triosephosphateisomerase (PfuTIM) display cold-denaturation upon cooling, and heat-renaturation upon reheating, in proportion with the extent of initial partial unfolding achieved. This was the first time that cold-denaturation was demonstrated for a hyperthermophile protein, following unlocking of surface salt bridges. Here, we describe the behavior of another hyperthermophile protein,...

  18. Exact Solution to the Extended Zwanzig Model for Quasi-Sigmoidal Chemically Induced Denaturation Profiles: Specific Heat and Configurational Entropy

    OpenAIRE

    Aguilar-Pineda, G. E.; Olivares-Quiroz, L.

    2014-01-01

    Temperature and chemically induced denaturation comprise two of the most characteristic mechanisms to achieve the passage from the native state N to any of the unstructured states Dj in the denatured ensemble in proteins and peptides. In this work we present a full analytical solution for the configurational partition function qs of a homopolymer chain poly-X in the extended Zwanzig model (EZM) for a quasisigmoidal denaturation profile. This solution is built up from an EZM exact solution in...

  19. Protein thermal denaturation is modulated by central residues in the protein structure network.

    Science.gov (United States)

    Souza, Valquiria P; Ikegami, Cecília M; Arantes, Guilherme M; Marana, Sandro R

    2016-03-01

    Network structural analysis, known as residue interaction networks or graphs (RIN or RIG, respectively) or protein structural networks or graphs (PSN or PSG, respectively), comprises a useful tool for detecting important residues for protein function, stability, folding and allostery. In RIN, the tertiary structure is represented by a network in which residues (nodes) are connected by interactions (edges). Such structural networks have consistently presented a few central residues that are important for shortening the pathways linking any two residues in a protein structure. To experimentally demonstrate that central residues effectively participate in protein properties, mutations were directed to seven central residues of the β-glucosidase Sfβgly (β-d-glucoside glucohydrolase; EC 3.2.1.21). These mutations reduced the thermal stability of the enzyme, as evaluated by changes in transition temperature (Tm ) and the denaturation rate at 45 °C. Moreover, mutations directed to the vicinity of a central residue also caused significant decreases in the Tm of Sfβgly and clearly increased the unfolding rate constant at 45 °C. However, mutations at noncentral residues or at surrounding residues did not affect the thermal stability of Sfβgly. Therefore, the data reported in the present study suggest that the perturbation of the central residues reduced the stability of the native structure of Sfβgly. These results are in agreement with previous findings showing that networks are robust, whereas attacks on central nodes cause network failure. Finally, the present study demonstrates that central residues underlie the functional properties of proteins. PMID:26785700

  20. Rhamnolipids--next generation surfactants?

    Science.gov (United States)

    Müller, Markus Michael; Kügler, Johannes H; Henkel, Marius; Gerlitzki, Melanie; Hörmann, Barbara; Pöhnlein, Martin; Syldatk, Christoph; Hausmann, Rudolf

    2012-12-31

    The demand for bio-based processes and materials in the petrochemical industry has significantly increased during the last decade because of the expected running out of petroleum. This trend can be ascribed to three main causes: (1) the increased use of renewable resources for chemical synthesis of already established product classes, (2) the replacement of chemical synthesis of already established product classes by new biotechnological processes based on renewable resources, and (3) the biotechnological production of new molecules with new features or better performances than already established comparable chemically synthesized products. All three approaches are currently being pursued for surfactant production. Biosurfactants are a very promising and interesting substance class because they are based on renewable resources, sustainable, and biologically degradable. Alkyl polyglycosides are chemically synthesized biosurfactants established on the surfactant market. The first microbiological biosurfactants on the market were sophorolipids. Of all currently known biosurfactants, rhamnolipids have the highest potential for becoming the next generation of biosurfactants introduced on the market. Although the metabolic pathways and genetic regulation of biosynthesis are known qualitatively, the quantitative understanding relevant for bioreactor cultivation is still missing. Additionally, high product titers have been exclusively described with vegetable oil as sole carbon source in combination with Pseudomonas aeruginosa strains. Competitive productivity is still out of reach for heterologous hosts or non-pathogenic natural producer strains. Thus, on the one hand there is a need to gain a deeper understanding of the regulation of rhamnolipid production on process and cellular level during bioreactor cultivations. On the other hand, there is a need for metabolizable renewable substrates, which do not compete with food and feed. A sustainable bioeconomy approach should

  1. DNA compaction by azobenzene-containing surfactant

    International Nuclear Information System (INIS)

    We report on the interaction of cationic azobenzene-containing surfactant with DNA investigated by absorption and fluorescence spectroscopy, dynamic light scattering, and atomic force microscopy. The properties of the surfactant can be controlled with light by reversible switching of the azobenzene unit, incorporated into the surfactant tail, between a hydrophobic trans (visible irradiation) and a hydrophilic cis (UV irradiation) configuration. The influence of the trans-cis isomerization of the azobenzene on the compaction process of DNA molecules and the role of both isomers in the formation and colloidal stability of DNA-surfactant complexes is discussed. It is shown that the trans isomer plays a major role in the DNA compaction process. The influence of the cis isomer on the DNA coil configuration is rather small. The construction of a phase diagram of the DNA concentration versus surfactant/DNA charge ratio allows distancing between three major phases: colloidally stable and unstable compacted globules, and extended coil conformation. There is a critical concentration of DNA above which the compacted globules can be hindered from aggregation and precipitation by adding an appropriate amount of the surfactant in the trans configuration. This is because of the compensation of hydrophobicity of the globules with an increasing amount of the surfactant. Below the critical DNA concentration, the compacted globules are colloidally stable and can be reversibly transferred with light to an extended coil state.

  2. DNA compaction by azobenzene-containing surfactant

    Science.gov (United States)

    Zakrevskyy, Yuriy; Kopyshev, Alexey; Lomadze, Nino; Morozova, Elena; Lysyakova, Ludmila; Kasyanenko, Nina; Santer, Svetlana

    2011-08-01

    We report on the interaction of cationic azobenzene-containing surfactant with DNA investigated by absorption and fluorescence spectroscopy, dynamic light scattering, and atomic force microscopy. The properties of the surfactant can be controlled with light by reversible switching of the azobenzene unit, incorporated into the surfactant tail, between a hydrophobic trans (visible irradiation) and a hydrophilic cis (UV irradiation) configuration. The influence of the trans-cis isomerization of the azobenzene on the compaction process of DNA molecules and the role of both isomers in the formation and colloidal stability of DNA-surfactant complexes is discussed. It is shown that the trans isomer plays a major role in the DNA compaction process. The influence of the cis isomer on the DNA coil configuration is rather small. The construction of a phase diagram of the DNA concentration versus surfactant/DNA charge ratio allows distancing between three major phases: colloidally stable and unstable compacted globules, and extended coil conformation. There is a critical concentration of DNA above which the compacted globules can be hindered from aggregation and precipitation by adding an appropriate amount of the surfactant in the trans configuration. This is because of the compensation of hydrophobicity of the globules with an increasing amount of the surfactant. Below the critical DNA concentration, the compacted globules are colloidally stable and can be reversibly transferred with light to an extended coil state.

  3. Tunable, antibacterial activity of silicone polyether surfactants.

    Science.gov (United States)

    Khan, Madiha F; Zepeda-Velazquez, Laura; Brook, Michael A

    2015-08-01

    Silicone surfactants are used in a variety of applications, however, limited data is available on the relationship between surfactant structure and biological activity. A series of seven nonionic, silicone polyether surfactants with known structures was tested for in vitro antibacterial activity against Escherichia coli BL21. The compounds varied in their hydrophobic head, comprised of branched silicone structures with 3-10 siloxane linkages and, in two cases, phenyl substitution, and hydrophilic tail of 8-44 poly(ethylene glycol) units. The surfactants were tested at three concentrations: below, at, and above their Critical Micelle Concentrations (CMC) against 5 concentrations of E. coli BL21 in a three-step assay comprised of a 14-24h turbidometric screen, a live-dead stain and viable colony counts. The bacterial concentration had little effect on antibacterial activity. For most of the surfactants, antibacterial activity was higher at concentrations above the CMC. Surfactants with smaller silicone head groups had as much as 4 times the bioactivity of surfactants with larger groups, with the smallest hydrophobe exhibiting potency equivalent to sodium dodecyl sulfate (SDS). Smaller PEG chains were similarly associated with higher potency. These data link lower micelle stability and enhanced permeability of smaller silicone head groups to antibacterial activity. The results demonstrate that simple manipulation of nonionic silicone polyether structure leads to significant changes in antibacterial activity. PMID:26057244

  4. Aqueous Foam Stabilized by Tricationic Amphiphilic Surfactants

    Science.gov (United States)

    Heerschap, Seth; Marafino, John; McKenna, Kristin; Caran, Kevin; Feitosa, Klebert; Kevin Caran's Research Group Collaboration

    2015-03-01

    The unique surface properties of amphiphilic molecules have made them widely used in applications where foaming, emulsifying or coating processes are needed. The development of novel architectures with multi-cephalic/tailed molecules have enhanced their anti-bacterial activity in connection with tail length and the nature of the head group. Here we report on the foamability of two triple head double, tail cationic surfactants (M-1,14,14, M-P, 14,14) and a triple head single tail cationic surfactant (M-1,1,14) and compare them with commercially available single headed, single tailed anionic and cationic surfactants (SDS,CTAB and DTAB). The results show that bubble rupture rate decrease with the length of the carbon chain irrespective of head structure. The growth rate of bubbles with short tailed surfactants (SDS) and longer, single tailed tricationic surfactants (M-1,1,14) was shown to be twice as high as those with longer tailed surfactants (CTAB, M-P,14,14, M-1,14,14). This fact was related to the size variation of bubbles, where the foams made with short tail surfactants exhibited higher polydispersivity than those with short tails. This suggests that foams with tricationic amphiphilics are closed linked to their tail length and generally insensitive to their head structure.

  5. Surfactants tailored by the class Actinobacteria

    Directory of Open Access Journals (Sweden)

    Johannes H Kügler

    2015-03-01

    Full Text Available Gloablly, the drive towards the establishment of a bio-based economy has resulted in an increased need for bio-based applications. This, in turn, has served as a driving force for the discovery and application of novel biosurfactants. The class Actinobacteria represents a vast group of microorganisms with the ability to produce a diverse range of secondary metabolites, including surfactants. Understanding the extensive nature of the biosurfactants produced by actinobacterial strains can assist in finding novel biosurfactants with new potential applications. This review therefore presents a comprehensive overview of the knowledge available on actinobacterial surfactants, the chemical structures that have been completely or partly elucidated, as well as the identity of the biosurfactant-producing strains. Producer strains of not yet elucidated compounds are discussed, as well as the original habitats of all the producer strains, which seems to indicate that biosurfactant production is environmentally driven. Methodology applied in the isolation, purification and structural elucidation of the different types of surface active compounds, as well as surfactant activity tests, are also discussed. Overall, actinobacterial surfactants can be summarized to include the dominantly occurring trehalose-comprising surfactants, other non-trehalose containing glycolipids, lipopeptides and the more rare actinobacterial surfactants. The lack of structural information on a large proportion of actinobacterial surfactants should be considered as a driving force to further explore the abundance and diversity of these compounds. This would allow for a better understanding of actinobacterial surface active compounds and their potential for biotechnological application.

  6. 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.

  7. On the structural denaturation of biological analytes in trapped ion mobility spectrometry - mass spectrometry.

    Science.gov (United States)

    Liu, Fanny C; Kirk, Samuel R; Bleiholder, Christian

    2016-06-01

    Key to native ion mobility/mass spectrometry is to prevent the structural denaturation of biological molecules in the gas phase. Here, we systematically assess structural changes induced in the protein ubiquitin during a trapped ion mobility spectrometry (TIMS) experiment. Our analysis shows that the extent of structural denaturation induced in ubiquitin ions is largely proportional to the amount of translational kinetic energy an ion gains from the applied electric field between two collisions with buffer gas particles. We then minimize the efficiency of the structural denaturation of ubiquitin ions in the gas phase during a TIMS experiment. The resulting "soft" TIMS spectra of ubiquitin are found largely identical to those observed on "soft" elevated-pressure ion mobility drift tubes and the corresponding calibrated cross sections are consistent with structures reported from NMR experiments for the native and A-state of ubiquitin. Thus, our analysis reveals that TIMS is useful for native ion mobility/mass spectrometry analysis. PMID:26998732

  8. Denaturing of plutonium by transmutation of minor-actinides for enhancement of proliferation resistance

    International Nuclear Information System (INIS)

    Feasibility study for the plutonium denaturing by utilizing minor-actinide transmutation in light water reactors has been performed. And the intrinsic feature of proliferation resistance of plutonium has been discussed based on IAEA's publication and Kessler's proposal. The analytical results show that not only 238Pu but also other plutonium isotopes with even-mass-number have very important role for denaturing of plutonium due to their relatively large critical mass and noticeably high spontaneous fission neutron generation. With the change of the minor-actinide doping ratio in U-Pu mix oxide fuel and moderator to fuel ratio, it is found that the reactor-grade plutonium from conventional light water reactors can be denatured to satisfy the proliferation resistance criterion based on the Kessler's proposal but not to be sufficient for the criterion based on IAEA's publication. It has been also confirmed that all the safety coefficients take negative value throughout the irradiation. (author)

  9. A single parameter representation of hygroscopic growth and cloud condensation nucleus activity – Part 3: Including surfactant partitioning

    OpenAIRE

    Kreidenweis, S.M.; Petters, M. D.

    2012-01-01

    Atmospheric particles can serve as cloud condensation nuclei in the atmosphere. The presence of surface active compounds in the particle may affect the critical supersaturation that is required to activate a particle. Modelling surfactants in the context of Köhler theory, however, is difficult because surfactant enrichment at the surface implies that a stable radial concentration gradient must exist in the droplet. In this study, we introduce a hybrid model that accounts for partitionin...

  10. Chemical denaturation of globular proteins at the air-water interface

    International Nuclear Information System (INIS)

    X-ray and neutron reflectometry has been used to probe the equilibrium surface structure of hen egg white lysozyme (lysozyme) and bovine β -lactoglobulin (β -lactoglobulin) under denaturing conditions at the air-water interface. This was achieved by performing experiments on 10 mg mL-1 protein solutions containing increasing concentrations of guanidinium hydrochloride For solutions containing no G.HCl, the surface structure of the proteins was represented by a two-layer model with total thicknesses of 48 Angstroms and 38 Angstroms for lysozyme and β -lactoglobulin, respectively. The total volume of a single protein molecule and the associated water molecules was determined to be approximately 45 (0.3) nm3 for lysozyme, and 60 (0.3) nm3 for β -lactoglobulin. The thickness dimensions and the total volumes compared favourably with the crystal dimensions of 45 x 30 x 30 Angstroms (40.5 nm3 ), and 36 x 36 x 36 Angstroms (47 nm3 ) for lysozyme and β -lactoglobulin, respectively. This comparison suggests that when no denaturant was present, the structures of lysozyme and β -lactoglobulin were near to their native conformations at the air-water The response to the presence of the chemical denaturant was different for each protein. The surface layer of β -lactoglobulin expanded at very low concentrations (0.2 mol dm-3 ) of G.HCl, where the lysozyme layer contracted. At higher concentrations, unfolding of both the proteins led to the formation of a third diffuse layer. In general, lysozyme appeared to be less responsive to the chemical denaturant, which is most likely a result of the higher disulfide content of lysozyme. A protocol allowing quantitative analysis of the contribution from the air-water interface to the chemical denaturation of a protein was developed. The protocol involved calculation of the Gibbs free energy of a protein at zero denaturant concentration, by using the change in the adsorbed layer thickness as an order parameter

  11. Surfactant-Templated Mesoporous Metal Oxide Nanowires

    Directory of Open Access Journals (Sweden)

    Hongmei Luo

    2010-01-01

    Full Text Available We demonstrate two approaches to prepare mesoporous metal oxide nanowires by surfactant assembly and nanoconfinement via sol-gel or electrochemical deposition. For example, mesoporous Ta2O5 and zeolite nanowires are prepared by block copolymer Pluronic 123-templated sol-gel method, and mesoporous ZnO nanowires are prepared by electrodeposition in presence of anionic surfactant sodium dodecyl sulfate (SDS surfactant, in porous membranes. The morphologies of porous nanowires are studied by scanning electron microscopy (SEM and transmission electron microscopy (TEM analyses.

  12. Surfactant treatment for acute respiratory distress syndrome

    OpenAIRE

    Lopez-Herce, J.; de Lucas, N; Carrillo, A.; Bustinza, A.; Moral, R.

    1999-01-01

    OBJECTIVE—To determine prospectively the efficacy of surfactant in acute respiratory distress syndrome.
STUDY DESIGN—Twenty patients, 1 month to 16 years of age, diagnosed with an acute pulmonary disease with severe hypoxaemia (PaO2/FiO2 < 100) (13 with systemic or pulmonary disease and seven with cardiac disease) were treated with one to six doses of 50-200 mg/kg of porcine surfactant administered directly into the trachea. The surfactant was considered to be effectiv...

  13. Retinopathy of prematurity in surfactant treated infants.

    OpenAIRE

    Rankin, S. J.; Tubman, T. R.; Halliday, H. L.; Johnston, S S

    1992-01-01

    Seventy six babies of less than 1500 g birth weight who had surfactant replacement therapy for severe respiratory distress syndrome were studied to assess the presence and stage of subsequent retinopathy of prematurity (ROP). A control group of 90 babies, matched for birth weight and gestational age, who did not have surfactant therapy were also studied. Threshold ROP or greater was found in 1.7% of the surfactant group and 7.8% of the controls. For the babies of less than 1000 g birth weight...

  14. Synthesis and Characterization of Zirconia Nanocrystallites by Cationic Surfactant and Anionic Surfactant

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    Study on nanomaterials has attracted great interests in recent years. In this article,zirconia nanocrystallites of different structures have been successfully synthesized via hydrothermal methods with cationic surfactant (CTAB) and anionic surfactant (SDS), respectively. Differential Scanning Calorimeter (DSC-TG), X-ray Diffractometer (XRD), Transmission Electron Microscope (TEM), Ultraviolet-Visible (UV-vis) and N2 adsorption-desorption analyses are used for their structure characteristics. The results show that the cationic surfactant has a distinctive direction effect on the formation of zirconia nanocrystallites, while the anionic surfactant has a self-assembly synergistic effect on them. The sample synthesized with the cationic surfactant presents good dispersion with the main phase of tetragonal zirconia, and the average nanocryst al size is around 15nm after calcination at 500 ℃. While the sample synthesized with the anionic surfactant exhibits a worm-like mesoporous structure with pure tetragonal phase after calcination at 500 ℃ and with good thermal stability.

  15. 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...

  16. 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.

  17. FTIR Examination Of Thermal Denaturation And Gel-Formation In Whey Proteins

    Science.gov (United States)

    Byler, D. M.; Purcell, James M.

    1989-12-01

    Second derivative Fourier-transform infrared [DR2-FTIR] spectra of β-lactoglobulin [RIG], serum albumin [BSA], and a-lactalbumin [aLA], three proteins found in bovine whey, are markedly different before and after thermal denaturation. In no case, however, do the heat-treated proteins unfold as completely as does alkaline-denatured RLG [1]. The spectra also suggest that, for RLG and BSA, formation of intermolecularly hydrogen-bonded (β-strands precedes the onset of heat-induced gelation.

  18. Protein dynamics in Brillouin light scattering: Termal denaturation of hen egg white lysozyme

    Science.gov (United States)

    Svanidze, A. V.; Lushnikov, S. G.; Kojima, S.

    2009-09-01

    Thermal denaturation of hen egg white lysozyme has been investigated by Brillouin light scattering in the temperature range from 297 to 350 K. Anomalies in the temperature dependences of velocity and damping of hypersound and also in the behavior of the intensity of Brillouin components for the lysozyme solution at thermal denaturation have been revealed. These anomalies are attributable to phase transformations of the protein in the high-temperature region. It has been shown that Brillouin light scattering is a suitable tool for studying the structural evolution of proteins.

  19. 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.

  20. Protein-mediated loops and phase transition in nonthermal denaturation of DNA

    International Nuclear Information System (INIS)

    We use a statistical mechanical model to study nonthermal denaturation of DNA in the presence of protein-mediated loops. We find that looping proteins which randomly link DNA bases located at a distance along the chain could cause a first-order phase transition. We estimate the denaturation transition time near the phase transition, which can be compared with experimental data. The model describes the formation of multiple loops via dynamical (fluctuational) linking between looping proteins, which is essential in many cellular biological processes

  1. Single-molecule denaturation and degradation of proteins by the AAA+ ClpXP protease

    OpenAIRE

    Shin, Yongdae; Davis, Joseph H.; Brau, Ricardo R.; Martin, Andreas; Kenniston, Jon A.; Baker, Tania A.; Sauer, Robert T.; Lang, Matthew J.

    2009-01-01

    ClpXP is an ATP-fueled molecular machine that unfolds and degrades target proteins. ClpX, an AAA+ enzyme, recognizes specific proteins, and then uses cycles of ATP hydrolysis to denature any native structure and to translocate the unfolded polypeptide into ClpP for degradation. Here, we develop and apply single-molecule fluorescence assays to probe the kinetics of protein denaturation and degradation by ClpXP. These assays employ a single-chain variant of the ClpX hexamer, linked via a single...

  2. Intrinsic Fluorescence as a Spectral Probe for Protein Denaturation Studies in the Presence of Honey

    Science.gov (United States)

    Wong, Y. H.; Kadir, H. A.; Tayyab, S.

    2015-11-01

    Honey was found to quench the intrinsic fluorescence of bovine serum albumin (BSA) in a concentration dependent manner, showing complete quenching in the presence of 5% (w/v) honey. Increasing the protein concentration up to 5.0 μM did not lead to the recovery of the protein fluorescence. Urea denaturation of BSA, which otherwise shows a two-step, three-state transition, using intrinsic fluorescence of the protein as the probe failed to produce any result in the presence of 5% (w/v) honey. Thus, intrinsic fluorescence cannot be used as a spectral probe for protein denaturation studies in the presence of honey.

  3. Denaturation of the simian virus 40 origin of replication mediated by human replication protein A.

    OpenAIRE

    Iftode, C.; Borowiec, J A

    1997-01-01

    The initiation of simian virus 40 (SV40) replication requires recognition of the viral origin of replication (ori) by SV40 T antigen, followed by denaturation of ori in a reaction dependent upon human replication protein A (hRPA). To understand how origin denaturation is achieved, we constructed a 48-bp SV40 "pseudo-origin" with a central 8-nucleotide (nt) bubble flanked by viral sequences, mimicking a DNA structure found within the SV40 T antigen-ori complex. hRPA bound the pseudo-origin wit...

  4. The molecular basis for the chemical denaturation of proteins by urea

    OpenAIRE

    Bennion, Brian J.; DAGGETT, VALERIE

    2003-01-01

    Molecular dynamics simulations of the protein chymotrypsin inhibitor 2 in 8 M urea at 60°C were undertaken to investigate the molecular basis of chemical denaturation. The protein unfolded rapidly under these conditions, but it retained its native structure in a control simulation in water at the same temperature. The overall process of unfolding in urea was similar to that observed in thermal denaturation simulations above the protein's Tm of 75°C. The first step in unfolding was expansion o...

  5. Surface-attached protein can retain its native structure or undergo denaturation

    Czech Academy of Sciences Publication Activity Database

    Ostatná, Veronika; Paleček, Emil

    Sant Feliu de Guixols (Costa Brava), 2009. s. 1. [ESF-EMBO Symposium, Biological Surfaces and Interfaces. 27.06.2009-02.07.2009, Sant Feliu de Guixols (Costa Brava)] R&D Projects: GA ČR(CZ) GP202/07/P497; GA AV ČR(CZ) KJB100040901; GA MŠk(CZ) LC06035 Institutional research plan: CEZ:AV0Z50040507; CEZ:AV0Z50040702 Keywords : native and denatured BSA * surface denaturation * constant current chronopotentiometry Subject RIV: BO - Biophysics

  6. Influence of drying and hydrothermal treatments on the denaturation of corn proteins

    OpenAIRE

    Odjo, Djosse Psijus Sylvanus; Malumba Kamba, Paul; Bera, François

    2013-01-01

    Corn (Zea mays L.) is the most abundant cereal grain produced in the world. It also provides a significant amount of protein in human and animal diets. During drying corn grains undergo several alterations including protein denaturation. A series of studies have been conducted in order to understand mechanisms behind denaturation of corn proteins during drying and heat moisture treatments. Using a laboratory fluidized-bed dryer, a flint corn variety have been dried between 54° and 130°C and s...

  7. Preparation of nanocrystalline MgO by surfactant assisted precipitation method

    International Nuclear Information System (INIS)

    Highlights: → Nanocrystalline magnesium oxide with high surface area. → MgO prepared with surfactant showed different morphologies compared with the sample prepared without surfactant. → MgO prepared with surfactant showed a plate-like shape. → Refluxing temperature and time and the surfactant to metal molar ratio affect the textural properties of MgO. -- Abstract: Nanocrystalline magnesium oxide with high surface area was prepared by a simple precipitation method using pluronic P123 triblock copolymer (Poly (ethylene glycol)-block, Poly (propylene glycol)-block, Poly (ethylene glycol)) as surfactant and under refluxing conditions. The prepared samples were characterized by X-ray diffraction (XRD), N2 adsorption (BET) and scanning and transmission electron microscopies (SEM and TEM). The obtained results revealed that the refluxing time and temperature and the molar ratio of surfactant to metal affect the structural properties of MgO, because of the changes in the rate and extent of P123 adsorption on the prepared samples. The results showed that the addition of surfactant is effective to prepare magnesium oxide with high surface area and affects the morphology of the prepared samples. With increasing the P123/MgO molar ratio to 0.05 the pore size distribution was shifted to larger size. The sample prepared with addition of surfactant showed a plate-like shape which was completely different with the morphology of the sample prepared without surfactant. The formation of nanoplate-like MgO was related to higher surface density of Mg ions on the (0 0 1) plane than that on the other planes of the Mg(OH)2 crystal. The (0 0 1) plane would be blocked preferentially by the adsorbed P123 molecules during the growing process of Mg(OH)2 nanoentities and the growth on the (0 0 1) plane would be markedly restricted, and the consequence is the generation of nanoplate-like MgO. In addition, increase in refluxing temperature and time increased the specific surface area of

  8. Artificial surfactant and natural surfactant. Comparative study of the effects on premature rabbit lungs.

    OpenAIRE

    Morley, C.; Robertson, B.; Lachmann, B; Nilsson, R.; Bangham, A; Grossmann, G.; Miller, N.

    1980-01-01

    Premature newborn rabbits, delivered on day 27 of gestation, were treated with tracheal deposition of dry artificial surfactant containing dipalmitoyl phosphatidylcholine and unsaturated phosphatidylglycerol (7:3), or crude natural surfactant prepared by centrifugation of lung wash from adult rabbits. Before receiving surfactant, the animals were allowed to breathe for 7--27 min; they were then subjected to artificial ventilation under standardised conditions. In comparison with littermate co...

  9. Investigation of loss of surfactants during enhanced oil recovery applications - adsorption of surfactants onto clay materials

    OpenAIRE

    Behrens, Eivind Joo

    2013-01-01

    Chemical flooding, or surfactant flooding, is a well known EOR technique which has been used worldwide for decades. For this method to be economically feasible, it is crucial to minimize the loss of surfactant to the reservoir. Currently the industry is considering combining chemical flooding with the newer technique of low salinity waterflooding which also has proved to be an efficient method for increasing oil recovery from reservoirs. In this study the adsorption of the anionic surfactant ...

  10. Late administration of surfactant replacement therapy increases surfactant protein-B content: a randomized pilot study

    OpenAIRE

    Keller, Roberta L; MERRILL, JEFFREY D.; Black, Dennis M.; Steinhorn, Robin H.; Eichenwald, Eric C.; Durand, David J.; RYAN, RITA M.; Truog, William E; Courtney, Sherry E.; Ballard, Philip L.; Ballard, Roberta A.

    2012-01-01

    Background: Surfactant dysfunction may contribute to the development of bronchopulmonary dysplasia (BPD) in persistently ventilated preterm infants. We conducted a multicenter randomized, blinded, pilot study to assess the safety and efficacy of late administration of doses of a surfactant protein-B (SP-B)-containing surfactant (calfactant) in combination with prolonged inhaled nitric oxide (iNO) in infants ≤1,000 g birth weight (BW). Methods: We randomized 85 preterm infants ventilated at 7–...

  11. Pulmonary Surfactant Surface Tension Influences Alveolar Capillary Shape and Oxygenation

    OpenAIRE

    Ikegami, Machiko; Weaver, Timothy E.; Grant, Shawn N.; Whitsett, Jeffrey A.

    2009-01-01

    Alveolar capillaries are located in close proximity to the alveolar epithelium and beneath the surfactant film. We hypothesized that the shape of alveolar capillaries and accompanying oxygenation are influenced by surfactant surface tension in the alveolus. To prove our hypothesis, surfactant surface tension was regulated by conditional expression of surfactant protein (SP)-B in Sftpb−/− mice, thereby inhibiting surface tension–lowering properties of surfactant in vivo within 24 hours after d...

  12. Surfactant modified clays’ consistency limits and contact angles

    OpenAIRE

    Akbulut, S.; Nese, Z; Arasan, S

    2012-01-01

    This study was aimed at preparing a surfactant modified clay (SMC) and researching the effect of surfactants on clays' contact angles and consistency limits; clay was thus modified by surfactants formodifying their engineering properties. Seven surfactants (trimethylglycine, hydroxyethylcellulose  octyl phenol ethoxylate, linear alkylbenzene sulfonic acid, sodium lauryl ether sulfate, cetyl trimethylammonium chloride and quaternised ethoxylated fatty amine) were used as surfactants in this st...

  13. Water and surfactant flooding at different wettability conditions

    OpenAIRE

    Criollo, Silvio Alejandro

    2011-01-01

    In a surfactant flooding of oil reservoirs, surfactant products are added to the injected water to reduce the oil-water interfacial tension (IFT) and thereby mobilize capillary trapped oil. The theory in classic surfactant floods is based on water-wet sandstone reservoirs. It is now known that the wettability of sandstone reservoirs is often characterized as mixed-wet. The classic theory for surfactant flooding cannot be applied. This thesis characterizes water flooding and surfactant flo...

  14. Stable isotope tracers to estimate lung surfactant metabolism in vivo

    OpenAIRE

    Lamonica, Giulia

    2013-01-01

    Aim of this thesis was to apply the stable isotopes technique to study pulmonary surfactant kinetics. Lung surfactant is essential to live, because it prevents the alveoli to collapse during normal breathing. Lung surfactant is composed of lipids and specific proteins, and nowadays it is well known that alterations on the composition and amount of surfactant are involved in acute and chronic lung diseases. This work presents two studies about lung surfactant kinetics. The first one i...

  15. Surfactant distribution in a co-surfactant high-internal phase emulsion under shear

    International Nuclear Information System (INIS)

    Full text: High-internal phase (Φ= 0.9) aqueous-in-oil emulsions of surfactant and co-surfactant concentrations were studied using small-angle neutron scattering (SANS) and simultaneous in-situ rheology measurements. The emulsions used were composed of a continuous oil phase consisting of differing amounts of hexadecane and d-hexadecane (for contrast matching experiments), a deutero-aqueous phase almost saturated with ammonium nitrate, an oil soluble stabilizing polyisobutylene-based surfactant and water-soluble poly-amide surfactant. Emulsions were produced at various surfactant concentrations near the emulsion stability limit to test the significance of each surfactant. Various contrast matching and unmatched emulsions were produced for SANS measurements to highlight particular components of the emulsion. We have connected the emulsions' macroscopic rheological behaviour to quantified changes in micro-scale and nano-scale structures by SANS measurements and corresponding model fits [1]. Shear thinning is explained by SANS-observed shear disruption of inter-droplet bi-Iayer links causing deflocculation to more spherical, less linked, aqueous droplets. Refinement to higher viscosity is accompanied by droplet size reduction, and loss of surfactant from the oil and water continuous phases. The refinement mechanism differs from the single surfactant system [2] due to significant elongation (50%) of the emulsion droplets, which manifests as a large vertical anisotropy in the integrated scattering intensity. We attempt to explain and quantify the coupled kinetics of the oil and water based surfactants from experimental results.

  16. Lung surfactant levels are regulated by Ig-Hepta/GPR116 by monitoring surfactant protein D.

    Science.gov (United States)

    Fukuzawa, Taku; Ishida, Junji; Kato, Akira; Ichinose, Taro; Ariestanti, Donna Maretta; Takahashi, Tomoya; Ito, Kunitoshi; Abe, Jumpei; Suzuki, Tomohiro; Wakana, Shigeharu; Fukamizu, Akiyoshi; Nakamura, Nobuhiro; Hirose, Shigehisa

    2013-01-01

    Lung surfactant is a complex mixture of lipids and proteins, which is secreted from the alveolar type II epithelial cell and coats the surface of alveoli as a thin layer. It plays a crucial role in the prevention of alveolar collapse through its ability to reduce surface tension. Under normal conditions, surfactant homeostasis is maintained by balancing its release and the uptake by the type II cell for recycling and the internalization by alveolar macrophages for degradation. Little is known about how the surfactant pool is monitored and regulated. Here we show, by an analysis of gene-targeted mice exhibiting massive accumulation of surfactant, that Ig-Hepta/GPR116, an orphan receptor, is expressed on the type II cell and sensing the amount of surfactant by monitoring one of its protein components, surfactant protein D, and its deletion results in a pulmonary alveolar proteinosis and emphysema-like pathology. By a coexpression experiment with Sp-D and the extracellular region of Ig-Hepta/GPR116 followed by immunoprecipitation, we identified Sp-D as the ligand of Ig-Hepta/GPR116. Analyses of surfactant metabolism in Ig-Hepta(+/+) and Ig-Hepta(-/-) mice by using radioactive tracers indicated that the Ig-Hepta/GPR116 signaling system exerts attenuating effects on (i) balanced synthesis of surfactant lipids and proteins and (ii) surfactant secretion, and (iii) a stimulating effect on recycling (uptake) in response to elevated levels of Sp-D in alveolar space. PMID:23922714

  17. Lung surfactant levels are regulated by Ig-Hepta/GPR116 by monitoring surfactant protein D.

    Directory of Open Access Journals (Sweden)

    Taku Fukuzawa

    Full Text Available Lung surfactant is a complex mixture of lipids and proteins, which is secreted from the alveolar type II epithelial cell and coats the surface of alveoli as a thin layer. It plays a crucial role in the prevention of alveolar collapse through its ability to reduce surface tension. Under normal conditions, surfactant homeostasis is maintained by balancing its release and the uptake by the type II cell for recycling and the internalization by alveolar macrophages for degradation. Little is known about how the surfactant pool is monitored and regulated. Here we show, by an analysis of gene-targeted mice exhibiting massive accumulation of surfactant, that Ig-Hepta/GPR116, an orphan receptor, is expressed on the type II cell and sensing the amount of surfactant by monitoring one of its protein components, surfactant protein D, and its deletion results in a pulmonary alveolar proteinosis and emphysema-like pathology. By a coexpression experiment with Sp-D and the extracellular region of Ig-Hepta/GPR116 followed by immunoprecipitation, we identified Sp-D as the ligand of Ig-Hepta/GPR116. Analyses of surfactant metabolism in Ig-Hepta(+/+ and Ig-Hepta(-/- mice by using radioactive tracers indicated that the Ig-Hepta/GPR116 signaling system exerts attenuating effects on (i balanced synthesis of surfactant lipids and proteins and (ii surfactant secretion, and (iii a stimulating effect on recycling (uptake in response to elevated levels of Sp-D in alveolar space.

  18. Effects of Interactions Among Surfactants,Water and Oil on Equilibrium Configuration of Surfactant-Water-Oil Systems

    Institute of Scientific and Technical Information of China (English)

    YUAN Yin-quan; SUN Zhi-bo; XIE Yun; ZOU Xian-wu

    2004-01-01

    The distribution and configuration of surfactants at interface in surfactant-water-oil systems have been investigated using discontinuous molecular dynamic simulations. There exists a certain equilibrium concentration of surfactants at interface for the systems with certain interactions among surfactant, water and oil. The interface length and equilibrium morphology of the systems are dependent on the equilibrium concentration of surfactants at interface and the total amount of surfactants. The interaction strengths among surfactant, water and oil determine the equilibrium concentration of surfactants at interface. Three typical configurations of surfactants at interface have been observed: ① surfactant molecules are perpendicular to the interface and arranged closely; ② perpendicular to the interface and arranged at interval of two particles; ③ lie down in the interface partly.

  19. Effects of surfactant mixtures, including Corexit 9527, on bacterial oxidation of acetate and alkanes in crude oil

    Energy Technology Data Exchange (ETDEWEB)

    Bruheim, P.; Bredholt, H.; Eimhjellen, K. [Norwegian Univ. of Science and Technology, Trondheim (Norway). Dept. of Biotechnology

    1999-04-01

    Mixtures of nonionic and anionic surfactants, including Corexit 9527, were tested to determine their effects on bacterial oxidation of acetate and alkanes in crude oil by cells pregrown on these substrates. Corexit 9527 inhibited oxidation of the alkanes in crude oil by Acinetobacter calcoaceticus ATCC 31012, while Span 80, a Corexit 9527 constituent, markedly increased the oil oxidation rate. Another Corexit 9257 constituent, the negatively charged dioctyl sulfosuccinate (AOT), strongly reduced the oxidation rate. The combination of Span 80 and AOT increased the rate, but not as much as Span 80 alone increased it, which tentatively explained the negative effect of Corexit 9527. The results of acetate uptake and oxidation experiments indicated that the nonionic surfactants interacted with the acetate uptake system while the anionic surfactant interacted with the oxidation system of the bacteria. The overall effect of Corexit 9527 on alkane oxidation by A. calcoaceticus ATCC 31012 thus seems to be the sum of the independent effects of the individual surfactants in the surfactant mixture. When Rhodococcus sp. strain 094 was used, the alkane oxidation rate decreased to almost zero in the presence of a mixture of Tergitol 15-S-7 and AOT even though the Tergitol 15-S-7 surfactant increased the alkane oxidation rate and AOT did not affect it. This indicated that there was synergism between the two surfactants rather than an additive effect like that observed for A. calcoaceticus ATCC 31012.

  20. Analysis of pulmonary surfactant in rat lungs after inhalation of nanomaterials: Fullerenes, nickel oxide and multi-walled carbon nanotubes.

    Science.gov (United States)

    Kadoya, Chikara; Lee, Byeong-Woo; Ogami, Akira; Oyabu, Takako; Nishi, Ken-ichiro; Yamamoto, Makoto; Todoroki, Motoi; Morimoto, Yasuo; Tanaka, Isamu; Myojo, Toshihiko

    2016-01-01

    The health risks of inhalation exposure to engineered nanomaterials in the workplace are a major concern in recent years, and hazard assessments of these materials are being conducted. The pulmonary surfactant of lung alveoli is the first biological entity to have contact with airborne nanomaterials in inhaled air. In this study, we retrospectively evaluated the pulmonary surfactant components of rat lungs after a 4-week inhalation exposure to three different nanomaterials: fullerenes, nickel oxide (NiO) nanoparticles and multi-walled carbon nanotubes (MWCNT), with similar levels of average aerosol concentration (0.13-0.37 mg/m(3)). Bronchoalveolar lavage fluid (BALF) of the rat lungs stored after previous inhalation studies was analyzed, focusing on total protein and the surfactant components, such as phospholipids and surfactant-specific SP-D (surfactant protein D) and the BALF surface tension, which is affected by SP-B and SP-C. Compared with a control group, significant changes in the BALF surface tension and the concentrations of phospholipids, total protein and SP-D were observed in rats exposed to NiO nanoparticles, but not in those exposed to fullerenes. Surface tension and the levels of surfactant phospholipids and proteins were also significantly different in rats exposed to MWCNTs. The concentrations of phospholipids, total protein and SP-D and BALF surface tension were correlated significantly with the polymorphonuclear neutrophil counts in the BALF. These results suggest that pulmonary surfactant components can be used as measures of lung inflammation. PMID:25950198

  1. Serum-surfactant SP-D correlates inversely to lung function in cystic fibrosis

    DEFF Research Database (Denmark)

    Olesen, Hanne Vebert; Holmskov, Uffe; Schiøtz, Peter Oluf; Sørensen, Grith Lykke

    2010-01-01

    BACKGROUND: Cystic fibrosis (CF) affects the lungs causing infections and inflammation. Surfactant protein D (SP-D) is an innate defense lectin primarily secreted in the lungs. We investigated the influence of the SP-D Met11Thr polymorphism on CF lung function; and serum SP-D as a marker for CF l...

  2. Functionalized lipids and surfactants for specific applications.

    Science.gov (United States)

    Kepczynski, Mariusz; Róg, Tomasz

    2016-10-01

    Synthetic lipids and surfactants that do not exist in biological systems have been used for the last few decades in both basic and applied science. The most notable applications for synthetic lipids and surfactants are drug delivery, gene transfection, as reporting molecules, and as support for structural lipid biology. In this review, we describe the potential of the synergistic combination of computational and experimental methodologies to study the behavior of synthetic lipids and surfactants embedded in lipid membranes and liposomes. We focused on select cases in which molecular dynamics simulations were used to complement experimental studies aiming to understand the structure and properties of new compounds at the atomistic level. We also describe cases in which molecular dynamics simulations were used to design new synthetic lipids and surfactants, as well as emerging fields for the application of these compounds. This article is part of a Special Issue entitled: Biosimulations edited by Ilpo Vattulainen and Tomasz Róg. PMID:26946243

  3. Chemical waterflooding techniques using complex surfactants

    Energy Technology Data Exchange (ETDEWEB)

    Finch, H.D.

    1970-06-02

    A partial complex of an anionic surfactant with a moderate molecular weight amino-nitrogen-containing salt and/or an anionic surfactant plus a low-water solubility N-substituted ammonium salt of an anionic surfactant are capable of enhanced oil recovery in an aqueous slug. The efficiency of a partially complexed system (sodium dodecylbenzene sulfonate and m-toluidine hydrochloride) is 0.9 with respect to the oil recovery capacity of Bryton petroleum sulfonate (molecular weight 430) plus sodium chlorides, as determined by thin layer chromatography. An aqueous slug of a second partially complexed system (mixtures of C/sub 12/-C/sub 15/ hydroformulation alcohol sulfates and aniline hydrochloride) was followed by a sodium chloride slug on a sand pack, reducing the residual oil to 3 percent PV. This surfactant solution is tolerant to at least 0.8M sodium chloride and 0.01M calcium chloride.

  4. Autonomic control of the pulmonary surfactant system and lung compliance in the lizard.

    Science.gov (United States)

    Wood, P G; Andrew, L K; Daniels, C B; Orgeig, S; Roberts, C T

    1997-01-01

    An increase in body temperature in the bearded dragon, Pogona vitticeps, is accompanied by an increase in the amount of pulmonary surfactant, a mixture of proteins and lipids, with the latter consisting predominantly of phospholipid and cholesterol. This increase may result from a temperature-induced change in autonomic input to the lungs, as perfusing the isolated lungs of P. vitticeps with either acetylcholine or adrenaline increases surfactant phospholipid release. However, whether acetylcholine acts via intrapulmonary sympathetic ganglia or directly on alveolar Type II cells is unknown. Moreover, the relative importance of circulating catecholamines and pulmonary sympathetic nerves on the control of the surfactant system is also obscure. Here, we describe the mechanism of the modulation of the surfactant system and the effect of this modulation on lung compliance. The role of acetylcholine was determined by perfusing isolated lungs with acetylcholine, acetylcholine and the ganglionic antagonist hexamethonium, or acetylcholine, hexamethonium, and the muscarinic antagonist atropine. Perfusing with acetylcholine significantly increased phospholipid release but did not affect cholesterol release. While histological examination of the lung revealed the presence of a large autonomic ganglion at the apex, blocking sympathetic ganglia with hexamethonium did not prevent the acetylcholine-mediated increase in phospholipid. However, the increase was inhibited by blocking muscarinic receptors with atropine, which indicates that acetylcholine acts on muscarinic receptors to stimulate phospholipid release. By increasing pulmonary smooth muscle tone, acetylcholine decreased opening pressure and increased static inflation pressures. Plasma levels of noradrenaline and adrenaline increased with increasing temperature and were accompanied by a greater surfactant content in the lungs. While surfactant content was also higher in animals that exercised, plasma levels of adrenaline

  5. Surfactants in the management of rhinopathologies

    OpenAIRE

    Rosen, Philip L.; Palmer, James N.; O'Malley, Bert W.; Cohen, Noam A.

    2013-01-01

    Background: Surfactants are a class of amphiphilic surface active compounds that show several unique physical properties at liquid–liquid or liquid–solid surface interfaces including the ability to increase the solubility of substances, lower the surface tension of a liquid, and decrease friction between two mediums. Because of these unique physical properties several in vitro, ex vivo, and human trials have examined the role of surfactants as stand-alone or adjunct therapy in recalcitrant ch...

  6. Process for making surfactant capped nanocrystals

    Science.gov (United States)

    Alivisatos, A Paul; Rockenberger, Joerg

    2002-01-01

    Disclosed is a process for making surfactant capped nanocrystals of transition metal oxides. The process comprises reacting a metal cupferron complex of the formula M Cup, wherein M is a transition metal, and Cup is a cupferron, with a coordinating surfactant, the reaction being conducted at a temperature ranging from about 250 to about 300 C., for a period of time sufficient to complete the reaction.

  7. Hydrophobic surfactant proteins and their analogues.

    Science.gov (United States)

    Walther, Frans J; Waring, Alan J; Sherman, Mark A; Zasadzinski, Joseph A; Gordon, Larry M

    2007-01-01

    Lung surfactant is a complex mixture of phospholipids and four surfactant-associated proteins (SP-A, SP-B, SP-C and SP-D). Its major function in the lung alveolus is to reduce surface tension at the air-water interface in the terminal airways by the formation of a surface-active film enriched in surfactant lipids, hence preventing cellular collapse during respiration. Surfactant therapy using bovine or porcine lung surfactant extracts, which contain only polar lipids and native SP-B and SP-C, has dramatically improved the therapeutic outcomes of preterm infants with respiratory distress syndrome (RDS). One important goal of surfactant researchers is to replace animal-derived therapies with fully synthetic preparations based on SP-B and SP-C, produced by recombinant technology or peptide synthesis, and reconstituted with selected synthetic lipids. Here, we review recent research developments with peptide analogues of SP-B and SP-C, designed using either the known primary sequence and three-dimensional (3D) structure of the native proteins or, alternatively, the known 3D structures of closely homologous proteins. Such SP-B and SP-C mimics offer the possibility of studying the mechanisms of action of the respective native proteins, and may allow the design of optimized surfactant formulations for specific pulmonary diseases (e.g., acute lung injury (ALI) or acute respiratory distress syndrome (ARDS)). These synthetic surfactant preparations may also be a cost-saving therapeutic approach, with better quality control than may be obtained with animal-based treatments. PMID:17575474

  8. A microscopic model for mixed surfactant vesicles

    OpenAIRE

    D Duque; Tarazona, P.; Chacon, E.

    1998-01-01

    A microscopic model which has proven useful in describing amphiphilic aggregates as inhomogeneities of a fluid is extended here to study the case of a two component surfactant mixture. We have chosen an effective interaction between the amphiphiles that mimics the mixture of cationic--anionic surfactants. In agreement with experiments, and other theoretical approaches, we find regions where spherical vesicles are stable, with a well defined radius. The experimental dependence of the radius on...

  9. Poly(ethylene oxide) surfactant polymers

    OpenAIRE

    VACHEETHASANEE, KATANCHALEE; WANG, SHUWU; QIU, YONGXING; Marchant, Roger E.

    2004-01-01

    We report on a series of structurally well-defined surfactant polymers that undergo surface-induced self-assembly on hydrophobic biomaterial surfaces. The surfactant polymers consist of a poly(vinyl amine) backbone with poly(ethylene oxide) and hexanal pendant groups. The poly(vinyl amine) (PVAm) was synthesized by hydrolysis of poly(N-vinyl formamide) following free radical polymerization of N-vinyl formamide. Hexanal and aldehyde-terminated poly (ethyleneoxide) (PEO) were simultaneously att...

  10. Surfactant apoprotein in nonmalignant pulmonary disorders.

    OpenAIRE

    Singh, G.; Katyal, S. L.

    1980-01-01

    Formalin-fixed, paraffin-embedded lungs exhibiting a variety of nonmalignant disorders were studied by immunoperoxidase staining using antibodies specific for surfactant apoprotein, IgG, IgM, IgA, albumin, fibrinogen, and lysozyme. Normal Type II pneumocytes showed staining for surfactant apoprotein in the perinuclear region only. The extent and intensity of staining for apoprotein was markedly increased in reactive Type II pneumocytes. This increase appeared to be a nonspecific reaction to l...

  11. BMP signaling is essential in neonatal surfactant production during respiratory adaptation.

    Science.gov (United States)

    Luo, Yongfeng; Chen, Hui; Ren, Siying; Li, Nan; Mishina, Yuji; Shi, Wei

    2016-07-01

    Deficiency in pulmonary surfactant results in neonatal respiratory distress, and the known genetic mutations in key components of surfactant only account for a small number of cases. Therefore, determining the regulatory mechanisms of surfactant production and secretion, particularly during the transition from prenatal to neonatal stages, is essential for better understanding of the pathogenesis of human neonatal respiratory distress. We have observed significant increase of bone morphogenetic protein (BMP) signaling in neonatal mouse lungs immediately after birth. Using genetically manipulated mice, we then studied the relationship between BMP signaling and surfactant production in neonates. Blockade of endogenous BMP signaling by deleting Bmpr1a (Alk3) or Smad1 in embryonic day 18.5 in perinatal lung epithelial cells resulted in severe neonatal respiratory distress and death, accompanied by atelectasis in histopathology and significant reductions of surfactant protein B and C, as well as Abca3, whereas prenatal lung development was not significantly affected. We then identified a new BMP-Smad1 downstream target, Nfatc3, which is known as an important transcription activator for surfactant proteins and Abca3. Furthermore, activation of BMP signaling in cultured lung epithelial cells was able to promote endogenous Nfatc3 expression and also stimulate the activity of an Nfatc3 promoter that contains a Smad1-binding site. Therefore, our study suggests that the BMP-Alk3-Smad1-Nfatc3 regulatory loop plays an important role in enhancing surfactant production in neonates, possibly helping neonatal respiratory adaptation from prenatal amniotic fluid environment to neonatal air breathing. PMID:27190064

  12. SURFACTANT - POLYMER INTERACTION FOR IMPROVED OIL RECOVERY

    Energy Technology Data Exchange (ETDEWEB)

    Unknown

    1998-10-01

    The goal of this research is to use the interaction between a surfactant and a polymer for efficient displacement of tertiary oil by improving slug integrity, adsorption and mobility control. Surfactant--polymer flooding has been shown to be highly effective in laboratory-scale linear floods. The focus of this proposal is to design an inexpensive surfactant-polymer mixture that can efficiently recover tertiary oil by avoiding surfactant slug degradation high adsorption and viscous/heterogeneity fingering. A mixture comprising a ''pseudo oil'' with appropriate surfactant and polymer has been selected to study micellar-polymer chemical flooding. The physical properties and phase behavior of this system have been determined. A surfactant-polymer slug has been designed to achieve high efficiency recovery by improving phase behavior and mobility control. Recovery experiments have been performed on linear cores and a quarter 5-spot. The same recovery experiments have been simulated using a commercially available simulator (UTCHEM). Good agreement between experimental data and simulation results has been achieved.

  13. Synthesis of high quality MCM-48 with binary cationic-nonionic surfactants.

    Science.gov (United States)

    Zhao, Wei; Li, Quanzhi; Wang, Lina; Chu, Jinglong; Qu, Jinkui; Li, Shaohua; Qi, Tao

    2010-05-18

    Highly ordered MCM-48 was synthesized in the hydrothermal system of a mixture of cationic cetyltrimethylammonium bromide (CTAB) and nonionic poly(ethylene glycol) monooctylphenyl ether (Tx-100) using water glass as the silicon source. The effect of various factors, such as the amount of surfactant, CTAB/Tx-100, Si source, crystallization temperature, and crystallization time, on the synthesis were discussed in detail. The local effective surfactant packing parameter theory and the charge balance theory were used to explain the reason that various factors can affect the product structure reasonably. Especially, the role of Tx-100 was expounded. The optimum synthesis conditions for MCM-48 were obtained. PMID:20225814

  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. Thermodynamics of non-ionic surfactant Triton X-100-cationic surfactants mixtures at the cloud point

    International Nuclear Information System (INIS)

    Highlights: → Non-ionic surfactants are used as emulsifier and solubilizate in such as textile, detergent and cosmetic. → Non-ionic surfactants occur phase separation at temperature as named the cloud point in solution. → Dimeric surfactants have attracted increasing attention due to their superior surface activity. → The positive values of ΔGcp0 indicate that the process proceeds nonspontaneous. - Abstract: This study investigates the effects of gemini and conventional cationic surfactants on the cloud point (CP) of the non-ionic surfactant Triton X-100 (TX-100) in aqueous solutions. Instead of visual observation, a spectrophotometer was used for measurement of the cloud point temperatures. The thermodynamic parameters of these mixtures were calculated at different cationic surfactant concentrations. The gemini surfactants of the alkanediyl-α-ω-bis (alkyldimethylammonium) dibromide type, on the one hand, with different alkyl groups containing m carbon atoms and an ethanediyl spacer, referred to as 'm-2-m' (m = 10, 12, and 16) and, on the other hand, with -C16 alkyl groups and different spacers containing s carbon atoms, referred to as '16-s-16' (s = 6 and 10) were synthesized, purified and characterized. Additions of the cationic surfactants to the TX-100 solution increased the cloud point temperature of the TX-100 solution. It was accepted that the solubility of non-ionic surfactant containing polyoxyethylene (POE) hydrophilic chain was a maximum at the cloud point so that the thermodynamic parameters were calculated at this temperature. The results showed that the standard Gibbs free energy (ΔGcp0), the enthalpy (ΔHcp0) and the entropy (ΔScp0) of the clouding phenomenon were found positive in all cases. The standard free energy (ΔGcp0) increased with increasing hydrophobic alkyl chain for both gemini and conventional cationic surfactants; however, it decreased with increasing surfactant concentration.

  16. 27 CFR 20.178 - Marks and brands on containers of specially denatured spirits.

    Science.gov (United States)

    2010-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2010-04-01 2010-04-01 false Marks and brands on... Dealers § 20.178 Marks and brands on containers of specially denatured spirits. (a) Required marks. Each... officer, or (2) Consist of a brand name, or consist of caution notices, or consist of other...

  17. Microbial community fingerprinting by differential display-denaturing gradient gel electrophoresis

    OpenAIRE

    Portillo Guisado, María del Carmen; Villahermosa, Desiré; Corzo Rodríguez, Alfonso; González Grau, Juan Miguel

    2011-01-01

    Complex microbial communities exhibit a large diversity, hampering differentiation by DNA fingerprinting. Herein, differential display-denaturing gradient gel electrophoresis is proposed. By adding a nucleotide to the 3′ ends of PCR primers, 16 primer pairs and fingerprints were generated per community. Complexity reduction in each partial fingerprint facilitates sample comparison.

  18. 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.

  19. Mesoscopic modeling of DNA denaturation rates: Sequence dependence and experimental comparison

    International Nuclear Information System (INIS)

    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

  20. Different denaturation pathways of TrpCage minipeptide triggered by urea and guanidinium

    Czech Academy of Sciences Publication Activity Database

    Heyda, J.; Jungwirth, Pavel; Dzubiella, J.

    Praha : Ústav organické chemie a biochemie AV ČR, v. v. i, 2012. s. 34-34. ISBN 978-80-86241-47-0. [Prague Protein Spring Meeting 2012. 03.05.2012-06.05.2012, Praha] Institutional support: RVO:61388963 Keywords : TrpCage * denaturation * urea * guanidinium Subject RIV: CF - Physical ; Theoretical Chemistry

  1. Urea and Guanidinium Induced Denaturation of a Trp-Cage Miniprotein

    Czech Academy of Sciences Publication Activity Database

    Heyda, Jan; Kožíšek, Milan; Bednárová, Lucie; Thompson, G.; Konvalinka, Jan; Vondrášek, Jiří; Jungwirth, Pavel

    2011-01-01

    Roč. 115, č. 28 (2011), s. 8910-8924. ISSN 1520-6106 R&D Projects: GA MŠk LC512; GA ČR GA203/08/0114 Institutional research plan: CEZ:AV0Z40550506 Keywords : trp-cage denaturation * urea * guanidinium * molecular dynamics Subject RIV: CC - Organic Chemistry Impact factor: 3.696, year: 2011

  2. Sequence-dependent denaturation energetics: A major determinant in amyloid disease diversity

    OpenAIRE

    Hammarström, Per; Jiang, Xin; Hurshman, Amy R.; Powers, Evan T.; Kelly, Jeffery W.

    2002-01-01

    Several misfolding diseases commence when a secreted folded protein encounters a partially denaturing microenvironment, enabling its self assembly into amyloid. Although amyloidosis is modulated by numerous environmental and genetic factors, single point mutations within the amyloidogenic protein can dramatically influence disease phenotype. Mutations that destabilize the native state predispose an individual to disease; however, thermodynamic stability alone does not reliably predict disease...

  3. 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.

  4. The effect of denaturation and reduction on cellobiohydrolase 1 from Trichoderma reesei

    Energy Technology Data Exchange (ETDEWEB)

    Woodward, J. (Oak Ridge National Lab., TN (USA)); Herrmann, P.C. (Andrews Univ., Berrien Springs, MI (USA))

    1990-01-01

    The origin of these studies from our interest in the use of protein denaturants to elute cellulase enzyme components from residual cellulosic substrates. A high concentration of the denaturant guanidine hydrochloride, required for elution, was found to only partially unfold the major component of T. reesei cellulase, cellobiohydrolase I(CBH I), and that the reason for the loss in catalytic activity was due to the competitive inhibition of this enzyme and not, as expected, due to its unfolding or denaturation. Papain digestion of CBH I generated core'' enzyme which, apparently, completely broke up upon reduction. These data are discussed in relation to structure/function relationships of this key cellulase enzyme component. In this paper studies on the effect of denaturation and reduction of CBH I are described. The rationale for these studies is to further our understanding of the structure and function relationships of this key cellulase enzyme and to determine the methodology for its successful unfolding and refolding that may be necessary for its recovery. 18 refs., 5 figs.

  5. Comparative analyses of amplicon migration behavior in differing denaturing gradient gel electrophoresis (DGGE) systems

    Science.gov (United States)

    Thornhill, D. J.; Kemp, D. W.; Sampayo, E. M.; Schmidt, G. W.

    2010-03-01

    Denaturing gradient gel electrophoresis (DGGE) is commonly utilized to identify and quantify microbial diversity, but the conditions required for different electrophoretic systems to yield equivalent results and optimal resolution have not been assessed. Herein, the influence of different DGGE system configuration parameters on microbial diversity estimates was tested using Symbiodinium, a group of marine eukaryotic microbes that are important constituents of coral reef ecosystems. To accomplish this, bacterial clone libraries were constructed and sequenced from cultured isolates of Symbiodinium for the ribosomal DNA internal transcribed spacer 2 (ITS2) region. From these, 15 clones were subjected to PCR with a GC clamped primer set for DGGE analyses. Migration behaviors of the resulting amplicons were analyzed using a range of conditions, including variation in the composition of the denaturing gradient, electrophoresis time, and applied voltage. All tests were conducted in parallel on two commercial DGGE systems, a C.B.S. Scientific DGGE-2001, and the Bio-Rad DCode system. In this context, identical nucleotide fragments exhibited differing migration behaviors depending on the model of apparatus utilized, with fragments denaturing at a lower gradient concentration and applied voltage on the Bio-Rad DCode system than on the C.B.S. Scientific DGGE-2001 system. Although equivalent PCR-DGGE profiles could be achieved with both brands of DGGE system, the composition of the denaturing gradient and application of electrophoresis time × voltage must be appropriately optimized to achieve congruent results across platforms.

  6. 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…

  7. A simple histological technique to improve immunostaining when using DNA denaturation for BrdU labelling.

    Science.gov (United States)

    Boulanger, Jenna J; Staines, William A; LeBlanc, Véronique; Khoo, Eve-Ling; Liang, Jacky; Messier, Claude

    2016-02-01

    The typical immunohistochemistry technique used to reveal 5-bromo-2'-deoxyuridine (BrdU) incorporation requires denaturation of the DNA by heat and acid to permeabilize the cell nucleus. This treatment can damage tissue and reduce the antigenicity of several proteins, which then leads to weak immunostaining and/or false negatives. We show that an overnight post-fixation step following immunohistochemistry for antigens of interest protects immunostaining during the acid/heat denaturation treatment for subsequent BrdU staining. We used this technique to study the differentiation of recently divided oligodendrocyte progenitor cells in NG2CreER:EYFP reporter mice. We used a GFP anti-EYFP antibody to maximize visualization of the EYFP-containing oligodendrocyte progenitor cells, Olig1, and GST-pi to confirm the cell phenotype. Immunostaining for GFP, Olig1, and GST-pi is reduced by DNA denaturation. We found that incorporating a post-fixation step after double immunostaining for GFP/Olig1 and GFP/GST-pi prior to DNA denaturation prevented the fading and false negatives associated with this treatment. This simple addition to BrdU immunohistochemistry protocols extends the range of proteins that can be detected in combination with BrdU, along with the number of antibodies that can be used successfully in the study of cell proliferation. PMID:26620201

  8. 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

  9. Equilibrium heat-induced denaturation of chitinase 40 from Streptomyces thermoviolaceus.

    Science.gov (United States)

    Pyrpassopoulos, Serapion; Vlassi, Metaxia; Tsortos, Achilleas; Papanikolau, Yannis; Petratos, Kyriacos; Vorgias, Constantinos E; Nounesis, George

    2006-08-01

    High-precision differential scanning calorimetry (DSC) and circular dichroism (CD) have been employed to study the thermal unfolding of chitinase 40 (Chi40) from Streptomyces thermoviolaceus. Chi40 belongs to family 18 of glycosyl hydrolase superfamily bearing a catalytic domain with a "TIM barrel"-like fold, which exhibits deviations from the (beta/alpha)8 fold. The thermal unfolding is reversible at pH = 8.0 and 9.0. The denatured state is characterized by extensive structural changes with respect to the native. The process is characterized by slow relaxation kinetics. Even slower refolding rates are recorded upon cooling. It is shown that the denaturation calorimetric data obtained at slow heating rate (0.17 K/min) are in excellent agreement with equilibrium data obtained by extrapolation of the experimental results to zero scanning rate. Analysis of the DSC results reveals that the experimental data can be successfully fitted using either a non-two-state sequential model involving one equilibrium intermediate, or an independent transitions model involving the unfolding of two Chi40 energetic domains to intermediate states. The stability of the native state with respect to the final denatured state is estimated, deltaG = 24.0 kcal/mol at 25 degrees C. The thermal results are in agreement with previous findings from chemical denaturation studies of a wide variety of (beta/alpha)8 barrel proteins, that their unfolding is a non-two-state process, always involving at least one unfolding intermediate. PMID:16685709

  10. Resistance to DNA denaturation in irradiated Chinese hamster V79 fibroblasts is linked to cell shape

    International Nuclear Information System (INIS)

    Exponentially growing Chinese hamster V79-171b lung fibroblasts seeded at high density on plastic (approximately 7 x 10(3) cells/cm2) flatten, elongate, and produce significant amounts of extracellular fibronectin. When lysed in weak alkali/high salt, the rate of DNA denaturation following exposure to ionizing radiation is exponential. Conversely, cells plated at low density (approximately 7 x 10(2) cells/cm2) on plastic are more rounded 24 h later, produce little extracellular fibronectin, and display unusual DNA denaturation kinetics after X-irradiation. DNA in these cells resists denaturation, as though constraints to DNA unwinding have developed. Cell doubling time and distribution of cells in the growth cycle are identical for both high and low density cultures as is cell survival in response to radiation damage. The connection between DNA conformation and cell shape was examined further in low density cultures grown in conditioned medium. Under these conditions, cells at low density were able to elongate, and DNA denaturation of low density cultures was identical to that of high density cultures. Conversely, cytochalasin D, which interferes with actin polymerization causing cells to round up and release fibronectin, allowed development of constraints in high density cultures. These results suggest that DNA conformation is sensitive to changes in cell shape which result when cells are grown in different environments. However, these changes in DNA conformation detected by the DNA unwinding assay do not appear to play a direct role in radiation-induced cell killing

  11. 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

    denaturing conditions at pH 2.3, helix conformations are still populated in 24% of the ensemble of molecules. The structure of HA4 at atomic resolution was assessed using nuclear magnetic resonance (NMR) spectroscopy. Long-range NOEs between remote residues at opposite peptide ends suggested the formation of...

  12. Detection of the end point temperature of thermal denatured protein in fish and chicken meat through SDS-PAGE electrophoresis

    Science.gov (United States)

    Gao, Hongwei; Mao, Mao; Liang, Chengzhu; Lin, Chao; Xiang, Jianhai

    2009-03-01

    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°C to 75°C, 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 patterns 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°C to 80°C.

  13. Facilitating protein denaturation in organic solvent and the contribution to the promoting dispersion of graphite nanoplatelets in a polymer

    Directory of Open Access Journals (Sweden)

    T. Liu

    2015-08-01

    Full Text Available Denatured proteins, natural macromolecules are very attractive for advanced nanocomposites owing to their multiple functional chemical groups. However, denaturation processes were only successfully conducted in an aqueous environment, limiting their broad applications in hydrophobic polymers. In this study, we report an effective approach of denaturing soy protein at nanoscale in an organic solvent. Further, the denatured soy protein was found to be able to infiltrate between the graphite nanoplatelet (GNP layers to reduce the thickness of GNPs and improve the dispersion of the nanoparticles in either the suspension or the final polymeric nanocomposites. As a result, remarkable improvements in transparency and electrical conductivity have been achieved for the nanocomposites with the GNPs treated by the denatured soy protein.

  14. 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.; Dobson, Christopher M.; Vendruscolo, Michele; Poulsen, Flemming M.

    2005-01-01

    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...... 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......Paramagnetic relaxation enhancement measurements in the denatured state of ACBP have provided distance restraints that have been used in computer simulations to determine the conformational ensembles representing the denatured states of ACBP under a variety of conditions. A detailed comparison of...

  15. DNA interaction with cis- and trans- isomers of photosensitive surfactant

    Science.gov (United States)

    Unksov, I. N.; Kasyanenko, N. A.

    2014-12-01

    Interaction between DNA and photosensitive cationic surfactant in a solution is studied. Studies were conducted to examine the impact of the surfactant in its cis- conformation on the size of DNA molecule and also to investigate the phase behavior of the system depending on DNA and surfactant concentration. We conclude that trans- isomer of surfactant requires its smaller concentration to reach the DNA compaction compared with cis- isomer received by UV radiation of solutions. Studies of DNA-surfactant systems were performed by means of spectrophotometry and viscometry. Variation of surfactant concentration enables us to determine the precipitation zone on phase diagram. From the viscosity study it can be indicated that precipitation zone is narrower for UV-radiated surfactant and it shifts to higher surfactant concentration. Also we examine the reversibility of DNA compaction in systems with the surfactant in its trans- form.

  16. DNA interaction with cis- and trans- isomers of photosensitive surfactant

    International Nuclear Information System (INIS)

    Interaction between DNA and photosensitive cationic surfactant in a solution is studied. Studies were conducted to examine the impact of the surfactant in its cis- conformation on the size of DNA molecule and also to investigate the phase behavior of the system depending on DNA and surfactant concentration. We conclude that trans- isomer of surfactant requires its smaller concentration to reach the DNA compaction compared with cis- isomer received by UV radiation of solutions. Studies of DNA-surfactant systems were performed by means of spectrophotometry and viscometry. Variation of surfactant concentration enables us to determine the precipitation zone on phase diagram. From the viscosity study it can be indicated that precipitation zone is narrower for UV-radiated surfactant and it shifts to higher surfactant concentration. Also we examine the reversibility of DNA compaction in systems with the surfactant in its trans- form

  17. Surfactant-dependent macrophage response to polypyrrole-based coatings electrodeposited on Ti6Al7Nb alloy

    Energy Technology Data Exchange (ETDEWEB)

    Mindroiu, Mihaela [University Polytechnica of Bucharest, Faculty of Applied Chemistry and Materials Science, 1-7 Polizu, 011061, Bucharest (Romania); Ion, Raluca [University of Bucharest, Department of Biochemistry and Molecular Biology, 91-95 Spl. Independentei, 050095, Bucharest (Romania); Pirvu, Cristian [University Polytechnica of Bucharest, Faculty of Applied Chemistry and Materials Science, 1-7 Polizu, 011061, Bucharest (Romania); Cimpean, Anisoara, E-mail: anisoara.cimpean@bio.unibuc.ro [University of Bucharest, Department of Biochemistry and Molecular Biology, 91-95 Spl. Independentei, 050095, Bucharest (Romania)

    2013-08-01

    In this study, polypyrrole (PPy) films were successfully synthesized on Ti6Al7Nb alloy by potentiostatic polymerization in the presence of poly(sodium 4-styrenesulfonate) (NaPSS), t-octylphenoxy polyethoxyethanol (Triton X-100) and N-dodecyl-β-D-maltoside (DM) surfactants. Atomic force microscopy (AFM) analysis of the PPy/surfactant composite films revealed a granular structure characterized by a lower surface roughness than un-modified PPy films. The results demonstrated that addition of surfactants, namely Triton X-100 and DM, can improve electrochemical film stability and corrosion resistance. Further, Triton X-100 enhanced the adhesive strength of PPy films to the substrate. The surfactant type also showed a great influence on the surface wettability, the highest hydrophilic character being observed in the case of PPy/PSS film. Few studies have been devoted to the elucidation of inflammatory cell response to PPy-based materials. Therefore, RAW 264.7 macrophages were cultured on PPy-surfactant films to determine whether they elicit a differential cell behavior in terms of cell adhesion, proliferation, cellular morphology and cytokine secretion. Our results highlight the dependence of macrophage response on the surfactants used in the pyrrole polymerization process and suggest that the immune response to biomaterials coated with PPy films might be controlled by the choice of surfactant molecules. Highlights: • We electrodeposited polypyrrole films on Ti6Al7Nb alloy using three surfactants. • Differences in electrostability and wettability of polypyrrole films were found. • Triton X increased and NaPSS decreased the adhesion of polypyrrole films to Ti6Al7Nb. • Cytoskeletal architecture and macrophage activation were affected by surfactants. • The hydrophilic PPy/PSS coating elicited the lowest inflammatory response.

  18. Interactions of organic contaminants with mineral-adsorbed surfactants

    Science.gov (United States)

    Zhu, L.; Chen, B.; Tao, S.; Chiou, C.T.

    2003-01-01

    Sorption of organic contaminants (phenol, p-nitrophenol, and naphthalene) to natural solids (soils and bentonite) with and without myristylpyridinium bromide (MPB) cationic surfactant was studied to provide novel insight to interactions of contaminants with the mineral-adsorbed surfactant. Contaminant sorption coefficients with mineral-adsorbed surfactants, Kss, show a strong dependence on surfactant loading in the solid. At low surfactant levels, the Kss values increased with increasing sorbed surfactant mass, reached a maximum, and then decreased with increasing surfactant loading. The Kss values for contaminants were always higher than respective partition coefficients with surfactant micelles (Kmc) and natural organic matter (Koc). At examined MPB concentrations in water the three organic contaminants showed little solubility enhancement by MPB. At low sorbed-surfactant levels, the resulting mineral-adsorbed surfactant via the cation-exchange process appears to form a thin organic film, which effectively "adsorbs" the contaminants, resulting in very high Kss values. At high surfactant levels, the sorbed surfactant on minerals appears to form a bulklike medium that behaves essentially as a partition phase (rather than an adsorptive surface), with the resulting Kss being significantly decreased and less dependent on the MPB loading. The results provide a reference to the use of surfactants for remediation of contaminated soils/sediments or groundwater in engineered surfactant-enhanced washing.

  19. Determination of anionic surfactants during wastewater recycling process by ion pair chromatography with suppressed conductivity detection

    Science.gov (United States)

    Levine, L. H.; Judkins, J. E.; Garland, J. L.; Sager, J. C. (Principal Investigator)

    2000-01-01

    A direct approach utilizing ion pairing reversed-phase chromatography coupled with suppressed conductivity detection was developed to monitor biodegradation of anionic surfactants during wastewater recycling through hydroponic plant growth systems and fixed-film bioreactors. Samples of hydroponic nutrient solution and bioreactor effluent with high concentrations (up to 120 mS electrical conductance) of inorganic ions can be analyzed without pretreatment or interference. The presence of non-ionic surfactants did not significantly affect the analysis. Dynamic linear ranges for tested surfactants [Igepon TC-42, ammonium lauryl sulfate, sodium laureth sulfate and sodium alkyl (C10-C16) ether sulfate] were 2 to approximately 500, 1 to approximately 500, 2.5 to approximately 550 and 3.0 to approximately 630 microg/ml, respectively.

  20. Atomic-level structure characterization of an ultrafast folding mini-protein denatured state.

    Directory of Open Access Journals (Sweden)

    Per Rogne

    Full Text Available Atomic-level analyses of non-native protein ensembles constitute an important aspect of protein folding studies to reach a more complete understanding of how proteins attain their native form exhibiting biological activity. Previously, formation of hydrophobic clusters in the 6 M urea-denatured state of an ultrafast folding mini-protein known as TC5b from both photo-CIDNP NOE transfer studies and FCS measurements was observed. Here, we elucidate the structural properties of this mini-protein denatured in 6 M urea performing (15N NMR relaxation studies together with a thorough NOE analysis. Even though our results demonstrate that no elements of secondary structure persist in the denatured state, the heterogeneous distribution of R(2 rate constants together with observing pronounced heteronuclear NOEs along the peptide backbone reveals specific regions of urea-denatured TC5b exhibiting a high degree of structural rigidity more frequently observed for native proteins. The data are complemented with studies on two TC5b point mutants to verify the importance of hydrophobic interactions for fast folding. Our results corroborate earlier findings of a hydrophobic cluster present in urea-denatured TC5b comprising both native and non-native contacts underscoring their importance for ultra rapid folding. The data assist in finding ways of interpreting the effects of pre-existing native and/or non-native interactions on the ultrafast folding of proteins; a fact, which might have to be considered when defining the starting conditions for molecular dynamics simulation studies of protein folding.

  1. A study of the microstructural and diffusion properties of poly(vinyl alcohol) cryogels containing surfactant supramolecular aggregates.

    Science.gov (United States)

    Tedeschi, Annamaria; Auriemma, Finizia; Ricciardi, Rosa; Mangiapia, Gaetano; Trifuoggi, Marco; Franco, Lorenzo; Rosa, Claudio De; Heenan, Richard K; Paduano, Luigi; D'Errico, Gerardino

    2006-11-23

    Surfactant-containing poly(vinyl alcohol) (PVA) cryogels have been prepared by drying and reswelling hydrogel patches, previously obtained by the freeze/thaw procedure, in decyltrimethylammonium bromide (C10TAB) aqueous solutions. The microstructural and diffusive properties of the resulting material have been characterized by a combined experimental strategy. Gravimetric measurements show that the cryogel maximum swelling is not affected by the surfactant. The surfactant concentration within the cryogel, measured by ion chromatography, is the same as that in the rehydrating surfactant solution. Electron paramagnetic resonance (EPR) spin-probe and small-angle neutron scattering (SANS) measurements show that surfactant self-aggregation in the gel is similar to that in water, occurring at the same critical concentration and resulting in the formation of micellar aggregates whose structure is not affected by the cryogel polymeric scaffold. However, both the micelle intradiffusion coefficients, measured by PGSE-NMR, and the spin-probe correlation times, measured by EPR, indicate that dynamic processes in the hydrogel are much slower than in bulk water. A quantitative analysis of these results suggests that the cryogel polymer-poor domains, in which surfactant molecules are solubilized, have an average dimension of approximately 0.1 microm. Interestingly the experimental data also show that the polymer-poor phase contains more polymer than expected, suggesting that the spinodal decomposition, which occurs during the freezing step of cryogel preparation, is not complete or prevented by ice formation. PMID:17107141

  2. Characterization of surfactant/hydrotalcite-like clay/glassy carbon modified electrodes: Oxidation of phenol

    International Nuclear Information System (INIS)

    The characteristics of hydrotalcite (HT)-like clay films containing ionic and nonionic surfactants and their ability to oxidize phenol have been examined. The HT clay (Co/Al-NO3) was synthesized by coprecipitation techniques and then modified with surfactants such as sodium dodecylbenzenesulfonate (SDBS), octylphenoxypolyethoxyethanol (TX100) or cetylpyridinium bromide (CPB). X-ray diffraction analysis revealed that the interlayer basal spacing varied depending on the type of surfactant retained by the HT. The presence of SDBS and CPB expanded the HT interlayer, which in the presence of TX100 did not show an appreciable change. Phenol oxidation is favored at surfactant-HT-GC modified electrodes, after a preconcentration time, compared to phenol oxidation at HT-GC or GC electrodes. Surfactant-HT-GC modified electrodes display good stability in continuous electrochemical phenol oxidation. At pH values between 6 and 10.8, both SDBS-HT-GC and TX100-HT-GC modified electrodes seem to be promising electrodes for the detection of phenol in water; while the CPB-HT-GC modified electrode should be affected by the inorganic anions

  3. Derecruitment Test and Surfactant Therapy in Patients with Acute Lung Injury

    Directory of Open Access Journals (Sweden)

    Alexey A. Smetkin

    2012-01-01

    Full Text Available Introduction. A recruitment maneuver (RM may improve gas exchange in acute lung injury (ALI. The aim of our study was to assess the predictive value of a derecruitment test in relation to RM and to evaluate the efficacy of RM combined with surfactant instillation in patients with ALI. Materials and Methods. Thirteen adult mechanically ventilated patients with ALI were enrolled into a prospective pilot study. The patients received protective ventilation and underwent RM followed by a derecruitment test. After a repeat RM, bovine surfactant (surfactant group, n=6 or vehicle only (conventional therapy group, n=7 was instilled endobronchially. We registered respiratory and hemodynamic parameters, including extravascular lung water index (EVLWI. Results. The derecruitment test decreased the oxygenation in 62% of the patients. We found no significant correlation between the responses to the RM and to the derecruitment tests. The baseline EVLWI correlated with changes in SpO2 following the derecruitment test. The surfactant did not affect gas exchange and lung mechanics but increased EVLWI at 24 and 32 hrs. Conclusions. Our study demonstrated no predictive value of the derecruitment test regarding the effects of RM. Surfactant instillation was not superior to conventional therapy and might even promote pulmonary edema in ALI.

  4. XPS study of the surfactant film adsorbed onto growing titania nanoparticles

    International Nuclear Information System (INIS)

    TiO2 particles, prepared by following a sol-gel preparative route, were submitted to hydrothermal growing stages in the presence of an anionic surfactant, sodium dodecyl-sulfate (SDS), at solution pH values corresponding, respectively, to positive surface charges and to the isoelectric point of the oxide. The concentration of the surfactant in the aqueous solution was varied in order to produce different conditions of self-aggregation between the amphiphilic molecules. XPS analyses were performed on the aged and dried precursors to characterize the surfactant films adsorbed onto the oxide. The regions of Ti 2p, O 1s, and C 1s were specifically investigated. The samples, calcined at 600 deg. C, were characterized for phase composition-crystallinity, by X-ray diffraction, and for surface area. The role played by the oxide-surfactant interactions and by the surfactant self-aggregation phenomena in affecting the physico-chemical properties of the powders is discussed

  5. Effect of boric acid on the severity of vapor explosions in pure water and surfactant solutions

    International Nuclear Information System (INIS)

    Four different dilute aqueous solutions of boric acid and surfactant/boric acid were tested to determine the impact of these coolant additives on the severity of vapor explosions in small-scale experiments with molten tin. Twelve grams of molten tin at 800 C were dropped into 6 l of coolant solution at room temperature; for each solution, the experiment was repeated 20 times. The coolants examined were pure water, 500 wppm boric acid solution, 2000 wppm boric acid solution, 5 wppm of a non-ionic surfactant (nonylphenol polyethylene glycol ether) in a 500 wppm boric acid solution, and 5 wppm of an ionic surfactant (dodecylbenzene sulfonate sodium salt) in a 500 wppm boric acid solution. Pressure and impulse data suggest that the presence of boric acid up to 2000 wppm concentration did not significantly affect the severity of the interactions. Particle size analysis, however, indicates that enhanced fragmentation took place at the higher concentration (2000 wppm). The data indicate that the presence of boric acid negates the potentially mitigating effects of the surfactant additives previously reported in experiments where the surfactants were added to pure water. (orig.)

  6. Effect of boric acid on the severity of vapor explosions in pure water and surfactant solutions

    Energy Technology Data Exchange (ETDEWEB)

    Skelton, W.T.W. [Georgia Inst. of Tech., Atlanta (United States). School of Mechanical Engineering; Dowling, M.F. [Georgia Inst. of Tech., Atlanta (United States). School of Mechanical Engineering; Abdel-Khalik, S.I. [Georgia Inst. of Tech., Atlanta (United States). School of Mechanical Engineering

    1995-04-01

    Four different dilute aqueous solutions of boric acid and surfactant/boric acid were tested to determine the impact of these coolant additives on the severity of vapor explosions in small-scale experiments with molten tin. Twelve grams of molten tin at 800 C were dropped into 6 l of coolant solution at room temperature; for each solution, the experiment was repeated 20 times. The coolants examined were pure water, 500 wppm boric acid solution, 2000 wppm boric acid solution, 5 wppm of a non-ionic surfactant (nonylphenol polyethylene glycol ether) in a 500 wppm boric acid solution, and 5 wppm of an ionic surfactant (dodecylbenzene sulfonate sodium salt) in a 500 wppm boric acid solution. Pressure and impulse data suggest that the presence of boric acid up to 2000 wppm concentration did not significantly affect the severity of the interactions. Particle size analysis, however, indicates that enhanced fragmentation took place at the higher concentration (2000 wppm). The data indicate that the presence of boric acid negates the potentially mitigating effects of the surfactant additives previously reported in experiments where the surfactants were added to pure water. (orig.).

  7. Anionic surfactant - Biogenic amine interactions: The role of surfactant headgroup geometry.

    Science.gov (United States)

    Penfold, Jeffrey; Thomas, Robert K; Li, Peixun

    2016-03-15

    Oligoamines and biogenic amines (naturally occurring oligoamines) are small flexible polycations. They interact strongly with anionic surfactants such as sodium dodecyl sulfate, SDS. This results in enhanced adsorption and the formation of layered structures and the formation of layered structures at the air-water interface which depends on surfactant concentration and solution pH. The effect of changing the surfactant headgroup geometry on that interaction and subsequent adsorption is reported here. Neutron reflectivity, NR, results for the surface adsorption of the anionic surfactant sodium diethylene glycol monododecyl ether sulfate, SLES, with the biogenic amine, spermine, are presented, and contrasted with previous data for SDS/spermine mixtures. The enhancement in the adsorption of the surfactant at the air-water interface where monolayer adsorption occurs is similar for both surfactants. However the regions of surfactant concentration and solution pH where surface multilayer adsorption occurs is less extensive for the SLES/spermine mixtures, and occurs only at low pH. The results show how changing the headgroup geometry by the introduction of the ethylene oxide linker group between the alkyl chain and sulfate headgroup modifies the polyamine - surfactant interaction. The increased steric constraint from the polyethylene oxide group disrupts the conditions for surface multilayer formation at the higher pH values. This has important consequences for applications where the modification or manipulation of the surface properties are required. PMID:26724704

  8. Surfactant nebulization versus instillation during high frequency ventilation in surfactant-deficient rabbits

    NARCIS (Netherlands)

    Dijk, PH; Heikamp, A; Oetomo, SB

    1998-01-01

    Surfactant nebulization improves lung function at low alveolar doses of surfactant. However, efficiency of nebulization is low, and lung deposition seems to depend on lung aeration. High frequency ventilation (HFV) has been shown to improve lung aeration. We hypothesize that the combination of HFV a

  9. Open lung ventilation preserves the response to delayed surfactant treatment in surfactant-deficient newborn piglets

    NARCIS (Netherlands)

    M.B. van Veenendaal; A.H. van Kaam; J.J. Haitsma; R. Lutter; B. Lachmann

    2006-01-01

    Objective: Delayed surfactant treatment (>2 hrs after birth) is less effective than early treatment in conventionally ventilated preterm infants with respiratory distress syndrome. The objective of this study was to evaluate if this time-dependent efficacy of surfactant treatment is also present dur

  10. Surfactant Enhanced Electroremediation of Phenanthrene

    Institute of Scientific and Technical Information of China (English)

    佘鹏; 杨建刚; 等

    2003-01-01

    Removal of hydrophobic organic contaminants(HOCs) form soil of low permeability by electroremediation was investigated by using phenanthrene and kaolinite as a model system.Tween 80 was added into the purging solution in order to enhance the solubility of phenanthrene.The effects of pH on the adsorption of phenanthrene and Tween 80 on kaolinite and the magnitude of ζ-potential of kaolinite were examined,respectively.The effects of electric field strength indicated by electric current on the electroremediation behavior,including the pH of purging solution,the conductivity,phenanthrene concentration and flow rate of effluent,were experimentally investigated,repectively,In case of an electric field of 25mA applied for 72 hours,over 90% of phenanthrene was removed from 424g(dry mass)of kaolinite at an energy consumption of 0.148kW.h.The experimental results described in present study show that the addition of surfactant into purging solution greatly enhances the removel of HOCs by electroremediation.

  11. The effects of alkylammonium counterions on the aggregation of fluorinated surfactants and surfactant ionic liquids.

    Science.gov (United States)

    Pottage, Matthew J; Greaves, Tamar L; Garvey, Christopher J; Tabor, Rico F

    2016-08-01

    The effects of organic counterions with varying carbon number on surfactant aggregation have been analysed by coupling perfluorooctanoate surfactant anions with various alkylammonium counterions. Both the degree of substitution (primary to tertiary) and alkyl chain length (0-3 carbons) of the counterions were varied to provide a comprehensive matrix of geometries and lipophilicities. Surface activity was measured using pendant drop tensiometry, while temperature-controlled small-angle neutron scattering was used to probe changes in aggregation morphology. It was found that the use of such alkylammonium counterions resulted in a strong preference for bilayer formation even at low surfactant concentration (separation wherein a surfactant-rich lamellar phase coexists with a dilute micellar phase. The results indicate that aggregation is controlled by a delicate balance of counterion size, hydrophilicity and diffuseness of charge, providing new methods for the subtle control of surfactant solutions. PMID:27156087

  12. Alcohol--Induced Polyelectrolyte-Surfactant Complex Coacervate Systems: Characterization and Applications in Enzyme and Protein Extraction

    Science.gov (United States)

    Nejati Moshtaghin, Mahboubeh

    The focus of this thesis is to achieve a better understanding of the newly discovered surfactant-polyelectrolyte complex coacervate (SPCC) systems induced by fluoroalcohol/acid as well as short chain aliphatic alcohol; and to elucidate their applications in extraction and enrichment of proteins and enzyme. We have discovered that fluoroalcohols and --acids induce complex coacervation and phase separation in the aqueous mixtures of oppositely charged anionic polyelectrolytes; specifically, sodium salts of polyacrylic acid and polymethacrylic acid and cationic surfactant (cetyltrimethylammonium bromide, CTAB) over a broad range of concentrations of mole fractions of the oppositely charged amphiphiles. Accordingly, these new classes of coacervators will significantly broaden the scope and facilitate engineering of new coacervate phases. Toward these goals, we have inspected the formation of surfactant-polyelectrolyte complex coacervates in the presence of fluoroalcohols namely hexafluoroisopropanol (HFIP) and Trifluoroethanol (TFE). Furthermore, the extent of coacervation as a function of concentrations the system components, and charge ratios of the oppositely charged amphiphiles has been investigated. Polyelectrolytes are considered to be milder reagents, as compared to surfactants, regarding proteins denaturation. This highlights the importance of a detailed investigation of the efficiency of our coacervate systems for extraction and preconcentration of proteins and enzymes, especially, when the biological activity of the extracted proteins needs to be maintained based on the objectives mentioned above, the results of the investigations have been organized in four chapters. In Chapter II, the phase behavior of the FA-SPCC will be investigated. The objective is to examine the phase behavior and phase properties with respect to the extent of coacervation in different solution conditions. In particular, the effects of different solution variables such as concentration

  13. Alterations of alveolar type II cells and intraalveolar surfactant after bronchoalveolar lavage and perfluorocarbon ventilation. An electron microscopical and stereological study in the rat lung

    Directory of Open Access Journals (Sweden)

    Burkhardt Wolfram

    2007-06-01

    Full Text Available Abstract Background Repeated bronchoalveolar lavage (BAL has been used in animals to induce surfactant depletion and to study therapeutical interventions of subsequent respiratory insufficiency. Intratracheal administration of surface active agents such as perfluorocarbons (PFC can prevent the alveolar collapse in surfactant depleted lungs. However, it is not known how BAL or subsequent PFC administration affect the intracellular and intraalveolar surfactant pool. Methods Male wistar rats were surfactant depleted by BAL and treated for 1 hour by conventional mechanical ventilation (Lavaged-Gas, n = 5 or partial liquid ventilation with PF 5080 (Lavaged-PF5080, n = 5. For control, 10 healthy animals with gas (Healthy-Gas, n = 5 or PF5080 filled lungs (Healthy-PF5080, n = 5 were studied. A design-based stereological approach was used for quantification of lung parenchyma and the intracellular and intraalveolar surfactant pool at the light and electron microscopic level. Results Compared to Healthy-lungs, Lavaged-animals had more type II cells with lamellar bodies in the process of secretion and freshly secreted lamellar body-like surfactant forms in the alveoli. The fraction of alveolar epithelial surface area covered with surfactant and total intraalveolar surfactant content were significantly smaller in Lavaged-animals. Compared with Gas-filled lungs, both PF5080-groups had a significantly higher total lung volume, but no other differences. Conclusion After BAL-induced alveolar surfactant depletion the amount of intracellularly stored surfactant is about half as high as in healthy animals. In lavaged animals short time liquid ventilation with PF5080 did not alter intra- or extracellular surfactant content or subtype composition.

  14. Exogenous surfactant application in a rat lung ischemia reperfusion injury model: effects on edema formation and alveolar type II cells

    Directory of Open Access Journals (Sweden)

    Richter Joachim

    2008-01-01

    peribronchovascular edema. Morphological changes of alveolar type II cells due to I/R are not affected by surfactant treatment. The beneficial effects of exogenous surfactant therapy are related to the intraalveolar activity of the exogenous surfactant.

  15. The Cold Denatured State of the C-terminal Domain of Protein L9 Is Compact and Contains Both Native and Non-native Structure

    OpenAIRE

    Shan, Bing; McClendon, Sebastian; Rospigliosi, Carla; Eliezer, David; Raleigh, Daniel P.

    2010-01-01

    Cold denaturation is a general property of globular proteins, and the process provides insight into the origins of the cooperativity of protein folding and the nature of partially folded states. Unfortunately, studies of protein cold denaturation have been hindered by the fact that the cold denatured state is normally difficult to access experimentally. Special conditions such as addition of high concentrations of denaturant, encapsulation into reverse micelles, the formation of emulsified so...

  16. MINERAL-SURFACTANT INTERACTIONS FOR MINIMUM REAGENTS PRECIPITATION AND ADSORPTION FOR IMPROVED OIL RECOVERY

    Energy Technology Data Exchange (ETDEWEB)

    P. Somasundaran

    2005-10-30

    In this project, fundamental studies were conducted to understand the mechanism of the interactions between polymer/surfactant and minerals with the aim of minimizing chemical loss by adsorption. The effects of chemical molecular structure on critical solid/liquid interfacial properties such as adsorption, wettability and surface tension in mineral/surfactant systems were investigated. The final aim is to build a guideline to design optimal polymer/surfactant formula based on the understanding of adsorption and orientation of surfactants and their aggregates at solid/liquid interface. During this period, the adsorption of mixed system of n-dodecyl-{beta}-D-maltoside (DM) and dodecyl sulfonate (C{sub 12}SO{sub 3}Na) was studied. Along with these adsorption studies, changes in mineral wettability due to the adsorption were determined under relevant conditions. pH was found to play a critical role in controlling total adsorption and mineral wettability. Previous studies have suggested significant surfactant loss by adsorption at neutral pH. But at certain pH, bilayer was found at lower adsorption density, which is beneficial for enhanced oil recovery. Analytical ultracentrifuge technique was successfully employed to study the micellization of DM/C{sub 12}SO{sub 3}Na mixtures. Compositional changes of the aggregates in solution were observed when two species were mixed. Surfactant mixture micellization affects the conformation and orientation of adsorption layer at mineral/water interface and thus the wettability and as a result, the oil release efficiency of the chemical flooding processes. Three surfactants C{sub 12}SO{sub 3}, AOT and SLE3 and one polymer were selected into three different binary combinations. Equilibrium surface tension measurement revealed complexation of polymer/surfactant under different conditions. Except for one combination of SLE3/ PVCAP, complexation was observed. It is to be noted that such complexation is relevant to both interfacial

  17. Syntheses of surfactants from oleochemical epoxides

    Directory of Open Access Journals (Sweden)

    Warwel Siegfried

    2001-01-01

    Full Text Available Sugar-based surfactants were obtained in good yields (up to 100% under mild conditions (70°C, methanol or mixtures of methanol and water by ring-opening of terminal epoxides with aminopolyols, derived from glucose. Reaction of N-methyl glucamine with epoxides from even-numbered C4-C18 alpha-olefins or from terminal unsaturated fatty acid methyl esters leads to linear products, while corresponding reactions with N-dodecyl glucamine or glucamine yield surfactants with different Y-structures. Products obtained by conversion of omega-epoxy fatty acid methyl esters were saponificated with NaOH or hydrolyzed enzymatically to sodium salts or free acids respectively, which are amphoteric surfactants. Studies of the surfactants at different pH-values demonstrate different surface active properties in aqueous solutions. Critical micelle concentrations (c.m.c. in a range between 2 and 500mg/l and surface tensions of 25-40mN/m were measured for several of the synthesized sugar-based surfactants. The ring-opening products are rather poor foamers, whereas some of the corresponding hydrobromides show good foaming properties.

  18. Recovering hydrocarbons with surfactants from lignin

    Energy Technology Data Exchange (ETDEWEB)

    Naae, D.G.; Whittington, L.E.; Ledoux, W.A.; Debons, F.E.

    1988-11-29

    This patent describes a method of recovering hydrocarbons from an underground hydrocarbon formation penetrated by at least one injection well and at least one production well, which comprises: injecting into the formation through an injection well a surfactant slug comprising about 0.1% to about 10% by weight of surfactants produced from lignin, the surfactants produced by placing lignin in contact with water, converting the lignin into low molecular weight lignin phenols by reducing the lignin in the presence of a reducing agent of carbon monoxide or hydrogen creating a reduction reaction mixture comprising oil soluble lignin phenols, the reduction occurring at a temperature greater than about 200/sup 0/C and a pressure greater than about 100 psi, recovering the oil soluble lignin phenols from the reduction mixture, and converting the lignin phenols into lignin surfactants by a reaction selected from the group consisting of alkoxylation, sulfonation, sulfation, aklylation, sulfomethylation, and alkoxysulfation; injecting into the formation through the injection well a drive fluid to push the surfactant slug towards a production well; and recovering hydrocarbons at the production well.

  19. Foaming behaviour of polymer-surfactant solutions

    International Nuclear Information System (INIS)

    We study the effect of a non-ionic amphiphilic polymer (PEG-100 stearate also called Myrj 59) on the foaming behaviour of aqueous solutions of an anionic surfactant (sodium dodecyl sulfate or SDS). The SDS concentration was kept fixed while the Myrj 59 concentration was varied. Measurements of foamability, surface tension and electrical conductivity were carried out. The results show two opposite effects depending on the polymer concentration: foamability is higher when the Myrj 59 concentration is low; however, it decreases considerably when the polymer concentration is increased. This behaviour is due to the polymer adsorption at the air/liquid interface at lower polymer concentrations, and to the formation of a polymer-surfactant complex in the bulk at higher concentrations. The results are confirmed by surface tension and electrical conductivity measurements, which are interpreted in terms of the microstructure of the polymer-surfactant solutions. The observed behaviour is due to the amphiphilic nature of the studied polymer. The increased hydrophobicity of Myrj 59, compared to that of water-soluble polymers like PEG or PEO, increases its 'reactivity' towards SDS, i.e. the strength of its interaction with this anionic surfactant. Our results show that hydrophobically modified polymers have potential applications as additives in order to control the foaming properties of surfactant solutions

  20. Rheology of Natural Lung Surfactant Films

    Science.gov (United States)

    Alonso, Coralie; Waring, Alan; Zsadzinski, Joseph

    2004-03-01

    The lung surfactant (LS) is a lipoprotein mixture lining the inside of the pulmonary alveoli which has the ability to lower the surface tension of the air-liquid hypophase interface to value near zero thus reducing the work of breathing and which also prevents the alveolar collapse. A lack or malfunction of lung surfactant, as it is often the case for premature infants, leads to respiratory distress syndrome. RDS can be treated by supplying replacement LS to the infants and several medications derived from natural sources, are now widely used. The lung surfactant is adsorbed at the air-liquid interface and is subjected to incessant compression expansion cycles therefore Langmuir monolayers provide a suitable model to investigate the physical properties of lung surfactant films. Using a magnetic needle rheometer, we measured the shear viscosity of natural lung surfactant spread at the air-liquid interface upon compression and expansion cycles for three different formulations. The shear viscosity of Survanta changes by orders of magnitude along one cycle while for Curosurf samples it changes only slightly and for Infasurf films it remains constant. These different behaviors can be explained by differences in composition between the three formulations leading to different organizations on the molecular scale.

  1. The role of surfactants in Köhler theory reconsidered

    Directory of Open Access Journals (Sweden)

    R. Sorjamaa

    2004-05-01

    Full Text Available Atmospheric aerosol particles typically consist of inorganic salts and organic material. The inorganic compounds as well as their hygroscopic properties are well defined, but the effect of organic compounds on cloud droplet activation is still poorly characterized. The focus of the present study is in the organic compounds that are surface active i.e. they concentrate on droplet surface and decrease droplet surface tension. Gibbsian surface thermodynamics were used to find out how partitioning in binary and ternary aqueous solutions affects the droplet surface tension and the droplet bulk concentration in droplets large enough to act as cloud condensation nuclei. Sodium dodecyl sulfate was used as a model compound together with sodium chloride to find out the effect the correct evaluation of surfactant partitioning has on the solute effect (Raoult effect. While the partitioning is known to lead to higher surface tension compared to a case in which partitioning is neglected, the present results show that the partitioning also alters the solute effect, and that the change is large enough to further increase the critical supersaturation and hence decrease the droplet activation. The fraction of surfactant partitioned to droplet surface increases with decreasing droplet size, which suggests that surfactants might enhance the activation of larger particles relatively more thus leading to less dense clouds. Cis-pinonic acid-ammonium sulfate aqueous solution was studied in order to relate the partitioning to more realistic atmospheric situation and to find out the combined effects of dissolution and partitioning behaviour. The results show that correct partitioning consideration alters the shape of the Köhler curve when compared to a situation in which the partitioning is neglected either completely or in the Raoult effect.

  2. Alkanediyl-α, ω-bis (dimethyl cetylammonium bromide gemini surfactants as novel corrosion inhibitors for mild steel in formic acid

    Directory of Open Access Journals (Sweden)

    Mohammad Mobin

    2012-12-01

    Full Text Available Gemini surfactants, butanediyl 1,4-bis(dimethyl cetylammonium bromide, pentanediyl 1,5 - bis (dimethyl cetylammonium bromide and hexanediyl 1,6 - bis (dimethyl cetylammonium bromide from Alkanediyl-α, ω-bis (dimethyl cetylammonium bromide series were synthesized in laboratory and were characterized by using Nuclear Magnetic Resonance (NMR spectroscopy. The surfactants were tested as corrosion inhibitors for mild steel in 20% formic acid. The influence of surfactants on mild steel corrosion inhibition was investigated by measuring the corrosion rate of mild steel in their absence and presence by weight loss measurements, solvent analysis of iron ions into the test solution and potentiodynamic polarization measurements. The surface morphology of the corroded steel samples in presence and absence of surfactants was evaluated by using Scanning Electron Microscopy (SEM. The synthesized gemini surfactants performed as excellent corrosion inhibitor, the inhibition efficiency (IE being in the range of 76.66-97.41%. The IE of surfactants is slightly affected by the spacer length. The IE increased with increase in surfactant concentration and temperature. The adsorption of gemini surfactants on the steel surface was found to obey Langmuir adsorption isotherm. The results of the potentiodynamic polarization studies are consistent with the results of weight loss studies.

  3. Interaction of Fluorocarbon Containing Hydrophobically Modified Polyelectrolyte with Nonionic Surfactants

    Institute of Scientific and Technical Information of China (English)

    GUO,Jin-Feng(郭金峰); ZHUANG,Dong-Qing(庄东青); ZHOU,Hui(周晖); ZHANG,Yun-Xiang(章云祥)

    2002-01-01

    The interaction of fluorocarbon containing hydrophobically modified polyelectrolyte (FMPAANa) with two kinds of nonionic surfactants (hydrogenated and fluorinated) in a semidilute (0.5 wt% ) aqueous solution had been studied by rheological measurements. Association behavior was found in both systems. The hydrophobic interaction of FMPAANa with fluorinated surfactant (FC171) is much stronger than that with hydrogenated surfactant (NP7.5) at low surfactant concentrations. The interaction is strengthened by surfactants being added for the density of active junctions increased. Whereas distinct phenomena for FC171 and NP7. 5 start to be found as the surfactants added over their respective certain concentration. The interaction of polyelectrolyte with fluorinated surfactant increases dramatical ly while that with hydrogenated surfactant decreases.

  4. Polyelectrolyte surfactant aggregates and their deposition on macroscopic surfaces

    CERN Document Server

    Voisin, D

    2002-01-01

    Oppositely charged surfactant and polyelectrolyte are present in hair shampoos and conditioners, together with particles (e.g. anti-dandruff agents for scalp) and droplets (e.g. silicone oil for the hair). These are normally formulated at high surfactant concentrations, beyond the flocculation region for the polyelectrolyte concentration used. However, on dilution with water, during application, flocs are formed which carry the particles and droplets to the scalp and hair. The addition of an anionic surfactant to an aqueous solution of cationic polyelectrolyte, at a given concentration, can lead to the formation of polyelectrolyte-surfactant 'particles', in which the surfactant 'binds' to the polyelectrolyte. This occurs from the critical association concentration (CAC), up to the surfactant concentration corresponding to maximum binding. Within this range of surfactant concentrations, the surfactant bound to the polyelectrolyte is thought to associate to form what might be termed 'internal micelles'. Each po...

  5. Fullerene surfactants and their use in polymer solar cells

    Science.gov (United States)

    Jen, Kwan-Yue; Yip, Hin-Lap; Li, Chang-Zhi

    2015-12-15

    Fullerene surfactant compounds useful as interfacial layer in polymer solar cells to enhance solar cell efficiency. Polymer solar cell including a fullerene surfactant-containing interfacial layer intermediate cathode and active layer.

  6. Synthesis of mesoporous nano-hydroxyapatite by using zwitterions surfactant

    Science.gov (United States)

    Mesoporous nano-hydroxyapatite (mn-HAP) was successfully synthesized via a novel micelle-templating method using lauryl dimethylaminoacetic acid as zwitterionic surfactant. The systematic use of such a surfactant in combination with microwave energy inputenables the precise contr...

  7. Natural surfactants used in cosmetics: glycolipids.

    Science.gov (United States)

    Lourith, N; Kanlayavattanakul, M

    2009-08-01

    Cosmetic surfactant performs detergency, wetting, emulsifying, solubilizing, dispersing and foaming effects. Adverse reactions of chemical synthesis surfactant have an effect on environment and humans, particularly severe in long term. Biodegradability, low toxicity and ecological acceptability which are the benefits of naturally derived surfactant that promises cosmetic safety are, therefore, highly on demand. Biosurfactant producible from microorganisms exhibiting potential surface properties suitable for cosmetic applications especially incorporate with their biological activities. Sophorolipids, rhamnolipids and mannosylerythritol lipids are the most widely used glycolipids biosurfactant in cosmetics. Literatures and patents relevant to these three glycolipids reviewed were emphasizing on the cosmetic applications including personal care products presenting the cosmetic efficiency, efficacy and economy benefits of glycolipids biosurfactant. PMID:19496839

  8. When do water-insoluble polyion-surfactant ion complex salts "redissolve" by added excess surfactant?

    Science.gov (United States)

    dos Santos, Salomé; Gustavsson, Charlotte; Gudmundsson, Christian; Linse, Per; Piculell, Lennart

    2011-01-18

    The redissolution of water-insoluble polyion-surfactant ion complexes by added excess of surfactant has systematically been investigated in experimental and theoretical phase equilibrium studies. A number of stoichiometric polyion-surfactant ion "complex salts" were synthesized and they consisted of akyltrimethylammonium surfactant ions of two different alkyl chain lengths (C(12)TA(+) and C(16)TA(+)) combined with homopolyions of polyacrylate of two different lengths (PA(-)(25) and PA(-)(6000)) or copolyions of acrylate and the slightly hydrophobic nonionic comonomers N-isopropylacrylamide (PA(-)-co-NIPAM) or N,N-dimethylacrylamide (PA(-)-co-DAM). The complex salts were mixed with water and excess alkyltrimethylammonium surfactant with either bromide or acetate counterions (C(n)TABr or C(n)TAAc). Factors promoting efficient redissolution were (i) very short polyions, (ii) a large fraction of NIPAM or DAM comonomers, and (iii) acetate, rather than bromide, as the surfactant counterion. Added C(12)TAAc gave an efficient redissolution of C(12)TAPA(25) but virtually no redissolution of C(12)TAPA(6000). A very efficient redissolution by added C(12)TAAc was obtained for PA(-)-co-NIPAM with 82 mol % of NIPAM. The C(12)TAPA-co-NIPAM/C(12)TAAc/H(2)O ternary phase diagram closely resembled the corresponding diagram for the much-studied pair cationic hydroxyethyl cellulose-(sodium) dodecyl sulfate. The simple Flory-Huggins theory adopted for polyelectrolyte systems successfully reproduced the main features of the experimental phase diagrams for the homopolyion systems, including the effect of the surfactant counterion. The efficient redissolution found for certain copolyion systems was explained by the formation of soluble polyion-surfactant ion complexes carrying an excess of surfactant ions through an additional hydrophobic attraction. PMID:21166446

  9. A Review on Progress in QSPR Studies for Surfactants

    OpenAIRE

    Zhengwu Wang; Xiaoyi Zhang; Jiwei Hu

    2010-01-01

    This paper presents a review on recent progress in quantitative structure-property relationship (QSPR) studies of surfactants and applications of various molecular descriptors. QSPR studies on critical micelle concentration (cmc) and surface tension (γ) of surfactants are introduced. Studies on charge distribution in ionic surfactants by quantum chemical calculations and its effects on the structures and properties of the colloids of surfactants are also reviewed. The trends of QSPR studies o...

  10. Identification of a cell membrane protein that binds alveolar surfactant.

    OpenAIRE

    Strayer, D. S.

    1991-01-01

    Alveolar surfactants are complex mixtures of proteins and phospholipids produced by type II alveolar cells and responsible for lowering pulmonary surface tension. The process by which surfactant is produced and exported and by which its production by pulmonary cells is regulated are not well understood. This study was designed to identify a cellular receptor for surfactant constituents. To do so, monoclonal anti-idiotypic antibodies directed against antibodies to porcine and rabbit surfactant...

  11. Surfactant-Polymer Interaction for Improved Oil Recovery

    Energy Technology Data Exchange (ETDEWEB)

    Gabitto, Jorge; Mohanty, Kishore K.

    2002-01-07

    The goal of this research was to use the interaction between a surfactant and a polymer for efficient displacement of tertiary oil by improving slug integrity, oil solubility in the displacing fluid and mobility control. Surfactant-polymer flooding has been shown to be highly effective in laboratory-scale linear floods. The focus of this proposal is to design an inexpensive surfactant-polymer mixture that can efficiently recover tertiary oil by avoiding surfactant slug degradation and viscous/heterogeneity fingering.

  12. A simplified treatment of surfactant effects on cloud drop activation

    OpenAIRE

    T. Raatikainen; Laaksonen, A.

    2011-01-01

    Dissolved surface active species, or surfactants, have a tendency to partition to solution surface and thereby decrease solution surface tension. Activating cloud droplets have large surface-to-volume ratios, and the amount of surfactant molecules in them is limited. Therefore, unlike with macroscopic solutions, partitioning to the surface can effectively deplete the droplet interior of surfactant molecules.

    Surfactant partitioning equilibrium for activating cloud droplet...

  13. Surfactant abnormalities in infants with severe viral bronchiolitis.

    OpenAIRE

    Dargaville, P A; South, M; McDougall, P N

    1996-01-01

    To determine whether abnormalities of pulmonary surfactant occur in infants with acute viral bronchiolitis, surfactant indices were measured in lung lavage fluid from 12 infants with severe bronchiolitis and eight infants without lung disease. Compared with controls, the bronchiolitis group showed deficiency of surfactant protein A (1.02 v 14.4 micrograms/ml) and disaturated phosphatidylcholine (35 v 1060 micrograms/ml) which resolved as the disease improved. Surfactant functional activity wa...

  14. A simplified treatment of surfactant effects on cloud drop activation

    OpenAIRE

    T. Raatikainen; Laaksonen, A.

    2010-01-01

    Dissolved surface active species, or surfactants, have a tendency to partition to solution surface and thereby decrease solution surface tension. Activating cloud droplets have large surface-to-volume ratios, and the amount of surfactant molecules in them is limited. Therefore, unlike with macroscopic solutions, partitioning to the surface can effectively deplete the droplet interior of surfactant molecules.

    Surfactant partitioning equilibrium for activating cloud droplet...

  15. Diluted porcine surfactant lung lavages in children with severe ARDS

    OpenAIRE

    2009-01-01

    Acute respiratory distress syndrome (ARDS) is characterized by damage to the arteriolar-capillary endothelium and alveolar epithelium that leads to surfactant deficiency and atelectasis. Alveolar collapse and pulmonary edema will further induce surfactant inactivation. Surfactant supplementation has been suggested but results are unpredictable. Poor response may be due to inhibition of administered surfactant by plasma components filling the alveolar space, severity of lung injury, time of su...

  16. Ab initio bubble-driven denaturation of double-stranded DNA: Self-mechanical theory.

    Science.gov (United States)

    Kuetche, Victor K

    2016-07-21

    Among the different theoretical models of the open-site-driven DNA-denaturation found in the literature, very few interests are actually paid to the fundamental unzipping process of the double-stranded DNA within the vicinity of its ground state condensate. In this paper, we address an alternative to better understand the process of denaturation of such a macromolecule by investigating the onset of its dynamics around its equilibrium state. We show that from the initiation of the transcription bubble by the promoter to the termination state, the open-states of the strands evolve dynamically while generating some localized waveguide channels with elastic scattering properties. We properly discuss the nonlinear dynamics of these structures within the viewpoint of the self-mechanical theory while inferring to the physical structure of the findings and their potential issues. PMID:27113786

  17. Dynamical Properties on the Thermal Denaturation of Lysozyme-Trehalose Solution

    Science.gov (United States)

    Sasanuma, Keita; Seshimo, Yuichi; Hashimoto, Eiji; Ike, Yuji; Kojima, Seiji

    2008-02-01

    We studied the dynamics of lysozyme solution and the bioprotective effect of trehalose. Thermodynamics and elastic properties related to the thermal denaturation were investigated by Modulated-temperature DSC (MDSC) and Brillouin scattering. By MDSC measurements, it is found that the thermal stability of lysozyme depends on the trehalose concentration, and trehalose suppresses the denaturation induced by pH change. The sound velocity of lysozyme-trehalose solution is studied as a function of trehalose concentration. With increasing trehalose concentration, the number density of tetrahedral structure of water molecules decreases. Furthermore, we reveal the interaction between lysozyme and trehalose increases, especially around room temperature. We suggerst that trehalose molecules tend to associate lysozyme by preferential hydration, and the trehalose-induced bioprotection phenomenon may result from the mechanical suppression of lysozyme unfolding.

  18. 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.

  19. Periodic force induced stabilization or destabilization of the denatured state of a protein

    CERN Document Server

    Ghosh, Pulak Kumar; Bag, Bidhan Chandra; 10.1063/1.3635774

    2012-01-01

    We have studied the effects of an external sinusoidal force in protein folding kinetics. The externally applied force field acts on the each amino acid residues of polypeptide chains. Our simulation results show that mean protein folding time first increases with driving frequency and then decreases passing through a maximum. With further increase of the driving frequency the mean folding time starts increasing as the noise-induced hoping event (from the denatured state to the native state) begins to experience many oscillations over the mean barrier crossing time period. Thus unlike one-dimensional barrier crossing problems, the external oscillating force field induces both \\emph{stabilization or destabilization of the denatured state} of a protein. We have also studied the parametric dependence of the folding dynamics on temperature, viscosity, non-Markovian character of bath in presence of the external field.

  20. Protective role of salt in catalysis and maintaining structure of halophilic proteins against denaturation

    Directory of Open Access Journals (Sweden)

    SunilKumarKhare

    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.

  1. Investigation of thermal denaturation of solid bovine serum albumin by terahertz dielectric spectroscopy

    Science.gov (United States)

    Li, Xiangjun; Fu, Xiuhua; Liu, Jianjun; Du, Yong; Hong, Zhi

    2013-10-01

    We investigate the thermal denaturation of solid bovine serum albumin (BSA) using terahertz time domain spectroscopy (THz-TDS). When the protein is heated up from 25 °C to 107 °C and cooled down to 25 °C again, an irreversible decrease in its THz absorption coefficient and refractive index is observed. The corresponding frequency-dependent permittivity during heating is fitted by the Debye model with single relaxation time. The relaxation times during temperature rising agree very well with Arrhenius equation with the activation energy of 6.52 kJ/(K·mol), which can be an indicator for the stability of BSA during thermal denaturation process.

  2. Dynamic Study of Gemini Surfactant and Single-chain Surfactant at Air/Water Interface

    Institute of Scientific and Technical Information of China (English)

    Yi Jian CHEN; Gui Ying XU; Shi Ling YUAN; Hai Ying SUN

    2005-01-01

    Molecular dynamics (MD) simulation are used to study the properties of gemini surfactant of ethyl-α,ω-bis(dodecyldimethylammonium bromide) (C12C2C12) and dodecyltrimethylammonium bromide (DTAB) at the air/water interface, respectively. In the two systems,the surfactant concentrations are both 28 wt. %, and other conditions are also the same. After reaching the thermodynamic equilibrium, the concentration profiles, the radial distributions functions (RDF) and the mean squared displacement (MSD) are investigated. Theresults reveal that the surface activity of C12C2C12 suffactant is higher than DTAB surfactant.

  3. Sequential treatments of premature lambs with an artificial surfactant and natural surfactant.

    OpenAIRE

    Ikegami, M; Jobe, A; Jacobs, H.; Jones, S. J.

    1981-01-01

    To test an artificial surfactant in vivo, six 120-d gestational age lambs were treated at birth with a mixture of a 9:1 M ratio of [14C]dipalmitoyl phosphatidylcholine (DPC) and phosphatidylglycerol at a dose of 100 mg DPC/kg. Nine other lambs were not treated. The mean PO2 values of the lambs treated with artificial surfactant were 65.7 +/- 11 mm Hg vs. 24.8 +/- 1.6 mm Hg for the untreated lambs (P less than 0.001). All lambs then were treated with 50 mg/natural surfactant lipid per kg, whic...

  4. Denaturation studies of active-site labeled papain using electron paramagnetic resonance and fluorescence spectroscopy.

    OpenAIRE

    Ping, Z A; Butterfiel, D A

    1991-01-01

    A spin-labeled p-chloromercuribenzoate (SL-PMB) and a fluorescence probe, 6-acryloyl-2-dimethylaminonaphthalene (Acrylodan), both of which bind to the single SH group located in the active site of papain, were used to investigate the interaction of papain (EC 3.4.22.2) with two protein denaturants. It was found that the active site of papain was highly stable in urea solution, but underwent a large conformational change in guanidine hydrochloride solution. Electron paramagnetic resonance and ...

  5. 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.

  6. Single-strand nuclease action on heat-denatured spermiogenic chromatin

    Energy Technology Data Exchange (ETDEWEB)

    Hunter, J.D.; Bodner, A.J.; Hatch, F.T.; Balhorn, R.L.; Mazrimas, J.A.; McQueen, A.P.; Gledhill, B.L.

    1976-01-01

    The sensitivity of chromatin was compared from representative cellular stages of spermiogenesis to a single-stranded nuclease after heat denaturation. Thermal denaturation of chromatin was assayed in situ in fixed round, elongating and elongated spermatids and in testicular sperm from mice. Production of single-stranded deoxyribonucleic acid (DNA) at elevated temperatures was monitored by digesting chromatin with endonuclease specific for single-stranded DNA (S/sub 1/ nuclease), staining the residual DNA with gallocyanin-chrome alum (GAC) and measuring the stain content by absorption cytophotometry. Changes in GCA staining were minimal over the temperature range of 22-90/sup 0/C in each cell type not exposed to nuclease. Staining of undigested cells decreased progressively with advancing cell maturity. Nuclease had no effect on the GCA content of round spermatids below 60/sup 0/C, but above this temperature there was a progressive decrease in GCA-stainable chromatin. Both round and elongating spermatid stages showed a significantly greater sensitivity to nuclease digestion than did more mature stages; sperm showed no effects of nuclease action below 80/sup 0/C. Progressive chromatin condensation and a concomitant decrease in the number of available DNA phosphate groups during spermiogenic cell maturation may be responsible for the observed decline in sensitivity to nuclease and decreased GCA staining. Thermal denaturation of roundspermatids labeled with /sup 3/H-thymidine produced no change in autoradiographic mean nuclear grain counts, indicating no loss of thymidine-labeled DNA from the slides during denaturation. When round spermatids and sperm were hydrolyzed with hot trichloracetic acid before staining, both nuclear GCA content and autoradiograph grain count were partially reduced, indicating incomplete DNA removal. Almost complete loss of Feulgenstainable material occurred in these cells and may be due to depurination and elimination of Fuelgren

  7. Interactions of competent Streptococcus sanguis (Wicky) cells with native or denatured, homologous or heterologous deoxyribonucleic acids.

    OpenAIRE

    Ranhand, J M

    1980-01-01

    Competent cell-deoxyribonucleic acid (DNA) interactions were examined using tritium-labeled homologous or heterologous native or denatured DNAs and competent Streptococcus sanguis Wicky cells (strain WE4). The DNAs used were extracted from WE4 cells, Escherichia coli B cells, and E. coli bacteriophages T2, T4, T6, and T7. The reactions examined were: (i) total DNA binding, (ii) deoxyribonuclease-resistant DNA binding, and (iii) the production of acid-soluble products from the DNA. Optimal tem...

  8. Thermal stability of chemically denatured green fluorescent protein (GFP) A preliminary study

    International Nuclear Information System (INIS)

    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 (λmax=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 -Ser65-Tyr66-Gly67-, which buried into β-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-1), but at 4 M it jumps to 8.4 and at greater concentration it is falling down to 1.1 kJ mol-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 β-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

  9. Molecular Fingerprinting of Dairy Microbial Ecosystems by Use of Temporal Temperature and Denaturing Gradient Gel Electrophoresis

    OpenAIRE

    Ogier, J.-C.; Lafarge, V.; Girard, V.; A. Rault; Maladen, V.; Gruss, A; Leveau, J.-Y.; Delacroix-Buchet, A

    2004-01-01

    Numerous microorganisms, including bacteria, yeasts, and molds, constitute the complex ecosystem present in milk and fermented dairy products. Our aim was to describe the bacterial ecosystem of various cheeses that differ by production technology and therefore by their bacterial content. For this purpose, we developed a rapid, semisystematic approach based on genetic profiling by temporal temperature gradient electrophoresis (TTGE) for bacteria with low-G+C-content genomes and denaturing grad...

  10. Stability of the larvicidal activity of Bacillus thuringiensis subsp. israelensis: amino acid modification and denaturants.

    OpenAIRE

    Pfannenstiel, M A; Couche, G A; G. Muthukumar; Nickerson, K W

    1985-01-01

    The Bacillus thuringiensis subsp. israelensis mosquito larvicidal toxin is not a sulfhydryl-activated toxin. The protein disulfide bonds were cleaved and blocked without loss of toxicity. In contrast, modification of the lysine side chains eliminated toxicity. Additionally, the toxin was resistant to high concentrations of salt (8 M NaBr), organic solvents (40% methanol), denaturants (4 M urea), and neutral detergents (10% Triton X-100). However, it was inactivated by both positively and nega...

  11. Electroanalysis of native, denatured and reduced BSA. Enhancement of peak H by guanidium chloride

    Czech Academy of Sciences Publication Activity Database

    Ostatná, Veronika; Paleček, Emil; Živanovic, Marko

    Jetřichovice, 2007. s. 125-126. ISBN 978-80-86238-05-0. [XXVII. Moderní elektrochemické metody. 21.05-2007-24.05.2007, Jetřichovice] R&D Projects: GA ČR(CZ) GP202/07/P497; GA MŠk(CZ) LC06035 Institutional research plan: CEZ:AV0Z50040507 Keywords : native, denatured and reduced BSA * guanidium chloride * constant current chronopotentiometry Subject RIV: BO - Biophysics

  12. Use of denatured radioalbumin for determination of trypsin and chymotrypsin inhibitors in different plant seeds

    International Nuclear Information System (INIS)

    The procedure for determination of trypsin and chymotrypsin inhibitors with urea-denatured albumin labeled by 125I is described. The content of both types of inhibitory activity has been determined in crude extracts of soybean, bean, lentil, pea, horse bean, maize, and 20 pea cultivars. The method is sufficiently sensitive, reliable, and particularly suitable when estimations must be done in crude plant extract with low inhibitory activity

  13. Generalized Poland-Scheraga denaturation model and two-dimensional renewal processes

    OpenAIRE

    Giacomin, Giambattista; Khatib, Maha

    2015-01-01

    The Poland-Scheraga model describes the denaturation transition of two complementary - in particular, equally long - strands of DNA, and it has enjoyed a remarkable success both for quantitative modeling purposes and at a more theoretical level. The solvable character of the homogeneous version of the model is one of features to which its success is due. In the bio-physical literature a generalization of the model, allowing different length and non complementarity of the strands, has been con...

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

    OpenAIRE

    Wouters Johan; Pouyez Jenny; Michaux Catherine; Privé Gilbert G

    2008-01-01

    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. Re...

  15. The 90-kDa Heat Shock Protein Hsp90 Protects Tubulin against Thermal Denaturation*

    OpenAIRE

    Weis, Felix; Moullintraffort, Laura; Heichette, Claire; Chrétien, Denis; Garnier, Cyrille

    2010-01-01

    Hsp90 and tubulin are among the most abundant proteins in the cytosol of eukaryotic cells. Although Hsp90 plays key roles in maintaining its client proteins in their active state, tubulin is essential for fundamental processes such as cell morphogenesis and division. Several studies have suggested a possible connection between Hsp90 and the microtubule cytoskeleton. Because tubulin is a labile protein in its soluble form, we investigated whether Hsp90 protects it against thermal denaturation....

  16. Native and denatured forms of proteins can be discriminated at edge plane carbon electrodes

    Czech Academy of Sciences Publication Activity Database

    Ostatná, Veronika; Černocká, Hana; Kurzatkowska, K.; Paleček, Emil

    2012-01-01

    Roč. 735, JUL (2012), s. 31-36. ISSN 0003-2670 R&D Projects: GA AV ČR(CZ) KJB100040901; GA ČR(CZ) GAP301/11/2055; GA MŠk(CZ) ME09038 Institutional research plan: CEZ:AV0Z50040702 Keywords : protein denaturation * carbon electrodes * edge plane pyrolytic graphite Subject RIV: BO - Biophysics Impact factor: 4.387, year: 2012

  17. A small heat shock/α-crystallin protein from encysted Artemia embryos suppresses tubulin denaturation

    OpenAIRE

    Day, Rossalyn M.; Gupta, Jagdish S.; MacRae, Thomas H.

    2003-01-01

    Small heat shock/α-crystallin proteins function as molecular chaperones, protecting other proteins from irreversible denaturation by an energy-independent process. The brine shrimp, Artemia franciscana, produces a small heat shock/α-crystallin protein termed p26, found in embryos undergoing encystment, diapause, and metabolic arrest. These embryos withstand long-term anoxia and other stresses normally expected to cause death, a property likely dependent on molecular chaperone activity. The as...

  18. Thermal and mechanical denaturation properties of a DNA model with three sites per nucleotide

    OpenAIRE

    Florescu, Ana-Maria; Joyeux, Marc

    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,...

  19. Isothermal Chemical Denaturation to Determine Binding Affinity of Small Molecules to G-Protein Coupled Receptors

    OpenAIRE

    Ross, Patrick; Weihofen, Wilhelm; Siu, Fai; Xie, Amy; Katakia, Hetal; Wright, S. Kirk; Hunt, Ian; Brown, Richard K; Freire, Ernesto

    2014-01-01

    The determination of accurate binding affinities is critical in drug discovery and development. Several techniques are available for characterizing the binding of small molecules to soluble proteins. The situation is different for integral membrane proteins. Isothermal chemical denaturation (ICD) has been shown to be a valuable biophysical method to determine in a direct and label-free fashion the binding of ligands to soluble proteins. In this communication, the application of isothermal che...

  20. Chemical denaturation as a tool in the formulation optimization of biologics

    OpenAIRE

    Freire, Ernesto; Schön, Arne; Hutchins, Burleigh M.; Brown, Richard K

    2013-01-01

    Biologics have become the fastest growing segment in the pharmaceutical industry. As is the case with all proteins, biologics are susceptible to denature or to aggregate; conditions that, if present, preclude their use as pharmaceuticals. Identifying the solvent conditions that maximize their structural stability is crucial during development. Since the structural stability of a protein is susceptible to different chemical and physical conditions, the use of several complementary techniques c...