Реферат
This study aims to prepare vitexin albumin nanoparticles(VT-BSA-NPs) to alleviate the low bioavailability of vitexin(VT) in vivo due to its poor water solubility. VT micro powders were prepared by the antisolvent crystallization method, and the morphology, size, and physicochemical properties of VT micro powders were studied. The results showed that the VT micro powder had a particle size of(187.13±7.15) nm, an approximate spherical morphology, and a uniform size distribution. Compared with VT, the chemical structure of VT micro powders has not changed. VT-BSA-NPs were prepared from VT micro powders by desolvation-crosslinking curing method. The preparation process was screened by single factor test and orthogonal test, and the quality evaluation of the optimal prescription particle size, PDI, Zeta potential, EE, and morphology was performed. The results showed that the average particle size of VT-BSA-NPs was(124.33±0.47) nm; the PDI was 0.184±0.012; the Zeta potential was(-48.83±2.20) mV, and the encapsulation rate was 83.43%±0.39%, all of which met the formulation-related requirements. The morphological results showed that the VT-BSA-NPs were approximately spherical in appearance, regular in shape, and without adhesion on the surface. In vitro release results showed a significantly reduced release rate of VT-BSA-NPs compared with VT, indicating a good sustained release effect. LC-MS/MS was used to establish an analytical method for in vivo analysis of VT and study the plasma pharmacokinetics of VT-BSA-NPs in rats. The results showed that the specificity of the analytical method was good, and the extraction recovery was more than 90%. Compared with VT and VT micro powders, VT-BSA-NPs could significantly increase AUC, MRT, and t_(1/2), which was beneficial to improve the bioavailability of VT.
Тема - темы
Rats , Animals , Serum Albumin, Bovine/chemistry , Chromatography, Liquid , Tandem Mass Spectrometry , Nanoparticles/chemistry , Particle Size , Drug Carriers/chemistryРеферат
In this work, a novel conjugate of ractopamine and bovine serum albumin (RAC-BSA) has been developed via the Mannich reaction, with a mole coupling ratio for RAC-BSA of 9:1. The proposed conjugation method provides a simple and one-step method with the use of fewer reagents compared with other conjugation methods for competitive immunoassays. RAC-BSA conjugation was used to fabricate a competitive lateral flow strip test for RAC detection in animal feed. For sample preparation, RAC was spiked in swine feed purchased from the local markets in Thailand, and methanol and running buffer at a volume ratio of 10:90 was used as extraction buffer. The procedures for sample preparation were completed within 25 min. Under optimal conditions, the limit of detection (LOD), assessed by the naked eye within 5 min, was found to be 1 ng/g. A semi-quantitative analysis was also conducted using a smart phone and computer software, with a linearity of 0.075-0.750 ng/g, calculated LOD of 0.10 ng/g, calculated limit of quantitation of 0.33 ng/g, and good correlation of 0.992. The recoveries were found in the range of 96.4%-103.7% with a relative standard deviation of 2.5%-3.6% for intra- and inter-assays. Comparison of the results obtained by the strip test with those obtained by enzyme-linked immunosorbent assay had a good agreement in terms of accuracy. Furthermore, this strip test exhibited highly specific RAC detection without cross reactivity with related compounds. Therefore, the RAC-BSA conjugation via the Mannich reaction can be accepted as a one-step and easy conjugation method and applied to the competitive lateral flow strip test.
Тема - темы
Animals , Animal Feed/analysis , Cross Reactions , Enzyme-Linked Immunosorbent Assay/methods , Limit of Detection , Phenethylamines/chemistry , Reagent Strips , Serum Albumin, Bovine/chemistry , SwineРеферат
This paper presents, from the perspective of technological development and production, the results of an investigation examining 61 clinical studies with vaccines conducted in Brazil between 1938-2013, with the participation of the Oswaldo Cruz Institute (IOC) and the Oswaldo Cruz Foundation (Fiocruz). These studies have been identified and reviewed according to criteria, such as the kind of vaccine (viral, bacterial, parasitic), their rationale, design and methodological strategies. The results indicate that IOC and Fiocruz have accumulated along this time significant knowledge and experience for the performance of studies in all clinical phases and are prepared for the development of new vaccines products and processes. We recommend national policy strategies to overcome existing regulatory and financing constraints.
Тема - темы
Animals , Animal Feed/adverse effects , Dietary Proteins/chemistry , Models, Biological , Proanthocyanidins/chemistry , Rumen/metabolism , Brassica rapa/chemistry , Chemical Precipitation , Dietary Proteins/metabolism , Fermentation , Fabaceae/adverse effects , Fabaceae/chemistry , Fruit/adverse effects , Fruit/chemistry , Molecular Structure , Molecular Weight , Osmolar Concentration , Plant Proteins/chemistry , Plant Proteins/metabolism , Proanthocyanidins/adverse effects , Proanthocyanidins/metabolism , Ruminants , Ribulose-Bisphosphate Carboxylase/chemistry , Ribulose-Bisphosphate Carboxylase/metabolism , Rumen/microbiology , Solubility , Stereoisomerism , Serum Albumin, Bovine/chemistry , Serum Albumin, Bovine/metabolismРеферат
Interaction of proteins with small molecules is important in understanding delivery and transport of different therapeutic agents, including drugs. In the present study, we investigated the interaction between hematoporphyrin (HP), the principal component of photosensitizing drug with bovine serum albumin (BSA) in aqueous buffer solution using UV-Vis absorption spectroscopy and fluorescence measurements. The results were further substantiated by molecular docking and molecular dynamics (MD) simulation. Our results revealed that fluorescence of BSA was dominantly quenched by the ground-state complex formation with HP accompanied by the electronic energy transfer (EET) to the later. We experimentally determined the thermodynamic parameters such as G0, H0, and S0 for the HP-BSA system which were -35.5 kJ mole-1, -56.4 kJ mole-1 and -0.06 kJ mole-1 K-1, respectively. These parameters suggested hydrogen-bonding and Van der Waals forces playing major role in the complexation. This was also supported by the binding energy parameters calculated by molecular docking. Moreover, the experimentally determined G0 nicely correlated with those determined by molecular docking and MD-simulation. Further, computational results clearly showed that the binding of HP with BSA in the subdomains IB and IIA.
Тема - темы
Animals , Hematoporphyrins/chemistry , Hematoporphyrins/chemistry , Hematoporphyrins/metabolism , Kinetics , Molecular Docking Simulation , Protein Binding , Protein Conformation , Serum Albumin, Bovine/chemistry , Serum Albumin, Bovine/metabolism , Spectrometry, Fluorescence , Spectroscopy, Fourier Transform Infrared , ThermodynamicsРеферат
Os antipsicóticos são drogas utilizadas no tratamento de muitos transtornos psiquiátricos, sendo classificados em dois grupos: típicos e atípicos. Os típicos formam o grupo de drogas que bloqueiam especialmente os receptores de dopamina e, por isto, causam efeitos colaterais característicos, que se manifestam através de sintomas extrapiramidais e podem terminar em discinesia tardia. Os atípicos apresentam eficácia antipsicótica similar à dos antipsicóticos típicos, mas produzem menos efeitos colaterais extrapiramidais e não causam discinesia tardia. Os antipsicóticos se ligam às proteínas plasmáticas, principalmente a albumina, a qual representa cerca de 60% do total das proteínas no soro humano. Neste trabalho estudamos os processos de interação de duas drogas antipsicóticas atípicas, risperidona e sulpirida, com as albuminas séricas humana (HSA) e bovina (BSA), através da técnica de supressão da fluorescência intrínseca do triptofano. A partir dos espectros de fluorescência, a análise dos dados foi feita obtendo-se os gráficos e as constantes de Stern-Volmer. A análise da supressão da fluorescência foi feita a partir da média aritmética dos dados oriundos dos experimentos realizados em cada condição adotada. Como a molécula da sulpirida é fluorescente desenvolvemos uma modelagem matemática do processo de interação, que nos permitiu então obter os dados referentes à supressão da fluorescência da proteína. Os resultados mostraram que a risperidona e a sulpirida suprimem a fluorescência de ambas albuminas por um processo de quenching estático, formando complexos droga-albumina. A risperidona tem uma afinidade com a HSA cerca de 6,5 vezes maior do que a sulpirida, a 37 oC. As constantes de associação calculadas para a interação risperidona-HSA, através da Teoria de Stern-Volmer, foram 1,43 (± 0,05) x 105 M-1, a 37 °C, e 2,56 (± 0,09) x 105 M-1, a 25 ºC1; e para a sulpirida, 2,20 (± 0,08) x 104 M-1, a 37 ºC, e 5,46 (± 0,20) x 104 M-1, a 25 ºC...
Antipsychotics are drugs used to treat many psychiatric disorders. They are classified into two groups: typical and atypical. The typical group act blocking dopamine receptors in particular and it causes characteristic side effects with extrapyramidal symptoms, and can lead to tardive dyskinesia. The atypical group presents similar efficacy to typical group, but they produce less extrapyramidal side effects and does not cause tardive dyskinesia. Antipsychotics bind to plasmatic proteins, mainly to albumin, which represents about 60% of total human serum proteins. In this study we studied the interactions of two atypical antipsychotic drugs, risperidone and sulpiride, with human serum albumin (HSA) and bovine (BSA) through the technique of intrinsic tryptophan fluorescence quenching. From the fluorescence spectra, a data analysis was made to obtain Stern-Volmer plots and constants. Quenching analysis was performed used from using arithmetic means of data from experiments for each adopted condition. As sulpiride molecule is fluorescent, a mathematical modeling for interaction process was made. It allows us then to obtain the data referents to fluorescence quenching of protein. Results showed that risperidone and sulpiride quench the fluorescence for both albumins by static quenching process, forming complexes drug-albumin. The risperidone affinity to HSA is about 6.5 higher than supiride, at 37 oC. Stern-Volmer constants for interaction risperidone-HSA were 1.43 (± 0.05) x 105 M-1, at 37oC, and 2.56 (± 0.09) x 105 M-1, at 25 oC; and for sulpiride were 2.20 (± 0.08) x 104 M-1, at 37 oC, and 5.46 (± 0.20) x 104 M-1, at 25 oC. As the quenching ratio for BSA was higher than HAS, we suggested that the primary site for risperidone on albumin is closer of the domain of trypthophan 134 of BSA than the domain of trypthophan 212 of HAS. The same is suggested for the primary site of supiride at 37oC.
Тема - темы
Antipsychotic Agents/pharmacology , /methods , Serum Albumin , Drug Interactions , Spectrometry, Fluorescence/methods , Mathematical Computing , Risperidone , Sulpiride , Serum Albumin, Bovine/chemistry , Tryptophan/chemistryРеферат
A monoclonal antibody (mAb) against zearalenone (ZEN) was produced using ZEN-carboxymethoxylamine and -BSA conjugates. Antibody produced by one clone showing a very high binding ability was selected and found to have a higher affinity for ZEN compared to a commerciall ZEN antibody. We developed two direct competitive ELISA systems using the selected antibody (ZEN-coated and anti-ZEN antibody-coated ELISA). Quantitative ranges for the anti-ZEN antibody-coated ELISA and ZEN-coated ELISA were from 25 to 750 ppb and from 12.5 to 100 ppb, respectively. The detection limit of both methods as measured with standard solutions was 10 ppb. The intra-plate and inter-well variation of both ELISAs were less than 10%. The IC50 values for alpha-zearalenol, beta-zearalenol, alpha-zearalanol, and beta-zearalanol compared to ZEN were 108.1, 119.3, 114.1, and 130.3% for the ZEN-coated ELISA. These values were 100.7, 120.7, 121.6, and 151.6% for the anti-ZEN antibody-coated ELISA. According to the anti-ZEN antibody-coated ELISA, the average recovery rates of ZEN from spiked animal feed containing 150 to 600 ng/mL of ZEN ranged from 106.07 to 123.00% with 0.93 to 2.28% coefficients of variation. Our results demonstrate that the mAb developed in this study could be used to simultaneously screen for ZEN and its metabolites in feed.
Тема - темы
Animals , Female , Mice , Aminooxyacetic Acid/chemistry , Antibodies, Monoclonal/immunology , Enzyme-Linked Immunosorbent Assay/methods , Inhibitory Concentration 50 , Mice, Inbred BALB C , Reproducibility of Results , Serum Albumin, Bovine/chemistry , Zearalenone/immunologyРеферат
The characteristics of the interaction between reserpine and bovine serum albumin (BSA) were studied by fluorescence, UV-vis absorption and Fourier transform infrared (FT-IR) spectroscopy. Spectroscopic analysis revealed that fluorescence quenching of BSA by reserpine was through a static quenching procedure. The binding constant KA of reserpine with BSA at 293, 301 and 309 K was 1.63, 1.78 and 2.35 × 105 moL-1 L respectively, which indicated degree of binding force between reserpine and BSA. There was one binding site between reserpine and BSA. The entropy and enthalpy changes were positive, indicating that interaction of reserpine and BSA was driven mainly by hydrophobic forces. The average binding distance between the donor (BSA) and the acceptor (reserpine) was about 3.84 nm based on the Förster non-radiation energy transfer theory. Results of synchronous fluorescence and FT-IR spectra indicated that the conformation and microenvironment of BSA were changed by the binding of reserpine. The results may provide important insights into the physiological activity of reserpine.
Тема - темы
Animals , Cattle , Reserpine/chemistry , Serum Albumin, Bovine/chemistry , Spectrometry, Fluorescence , Spectroscopy, Fourier Transform Infrared , Animals , Cattle , Reserpine/chemistry , Serum Albumin, Bovine/chemistry , Spectrometry, Fluorescence , Spectroscopy, Fourier Transform InfraredРеферат
The interaction of erythrosine B (ErB), a commonly used dye for coloring foods and drinks, with bovine serum albumin (BSA) was investigated both in the absence and presence of bilirubin (BR) using absorption and absorption difference spectroscopy. ErB binding to BSA was reflected from a significant red shift of 11 nm in the absorption maximum of ErB (527 nm) with the change in absorbance at λmax. Analysis of absorption difference spectroscopic titration results of BSA with increasing concentrations of ErB using Benesi-Hildebrand equation gave the association constant, K as 6.9 104 M-1. BR displacing action of ErB was revealed by a significant blue shift in the absorption maximum, accompanied by a decrease in absorbance difference at λmax in the difference spectrum of BR-BSA complex upon addition of increasing concentrations of ErB. This was further substantiated by fluorescence spectroscopy, as addition of increasing concentrations of ErB to BR-BSA complex caused a significant decrease in fluorescence at 510 nm. The results suggest that ErB binds to a site in the vicinity of BR binding site on BSA. Therefore, intake of ErB may increase the risk of hyperbilirubinemia in the healthy subjects.
Тема - темы
Animals , Bilirubin/chemistry , Binding Sites , Cattle , Erythrosine/chemistry , Erythrosine/metabolism , Kinetics , Protein Binding , Serum Albumin/chemistry , Serum Albumin, Bovine/chemistry , Spectrometry, Fluorescence/methods , TemperatureРеферат
Efonidipine hydrochloride is an antihypertensive and antianginal agent with fewer side effects and is better tolerated in the treatment of hypertension with renal impairment. Its interaction with bovine serum albumin (BSA) is of great use for the understanding of the pharmacokinetic and pharmacodynamic mechanisms of the drug. The binding of efonidipine to BSA was investigated by fluorescence spectroscopy and circular dichroism. BSA fluorescence was quenched by efonidipine, due to the fact that efonidipine quenched the fluorescence of tryptophan residues mainly by the collision mode. The thermodynamic parameters ÄH0 and ÄS0 were 68.04 kJ/mol and 319.42 J·mol-1·K-1, respectively, indicating that the hydrophobic interactions played a major role. The results of circular dichroism and synchronous fluorescence measurements showed that the binding of efonidipine to BSA led to a conformational change of BSA. The fraction of occupied sites (è) for the 8-anilino-1-naphthalein-sulfonic acid (ANS)-BSA system is 85 percent, whereas for the NZ-105-BSA system, it is 53 percent, which suggests that the interaction of ANS with BSA is stronger than that of NZ-105 with BSA. Binding studies in the presence of ANS indicated that efonidipine competed with ANS for hydrophobic sites of BSA. The effects of metal ions on the binding constant of the efonidipine-BSA complex were also investigated. The presence of metal ions Zn2+, Mg2+, Al3+, K+, and Ca2+ increased the binding constant of efonidipine_BSA complex, which may prolong the storage period of NZ-105 in blood plasma and enhance its maximum effects.
Тема - темы
Animals , Cattle , Dihydropyridines/chemistry , Nitrophenols/chemistry , Serum Albumin, Bovine/chemistry , Circular Dichroism , Models, Chemical , Organophosphorus Compounds/chemistry , Spectrometry, Fluorescence , ThermodynamicsРеферат
The conventional method of Fiske and Subba Row for the estimation of inorganic phosphate (Pi) is although rapid, but suffers from the disadvantage that the color is unstable and hence the optical density (OD) measurements have to be carried out within a short time span of 8-12 min. This poses a restriction on the number of samples, which can be handled in a batch. Although, modified procedures involving use of alternate reducing agents/or increasing the concentration of H2SO4 in conventional method have been subsequently developed, but the problem of color stability could not be solved. In addition, the use of higher concentrations H2SO4 has rendered the methods unsuitable in enzyme assays, especially if the acid labile phosphate containing substrates have been used. In the present study, attempts have been made to suitably modify the method to improve the stability of the color and sensitivity and also for its applicability in enzyme assays, especially when acid labile phosphate containing substrates such as ATP is used. We used the higher concentrations (0.625, 0.8 and 1.0 N) of H2SO4 rather than 0.5 N used in the conventional assay procedures. Under these conditions, the reagent blanks do not develop color for up to 24 h, whereas the intensity of the molybdenum blue color in the standard and/or experimental tubes increased with time reaching optimum value at 24 h. Simultaneously, the absorption maximum shifts from 660 nm to 820 nm. The highest concentration of H2SO4 (1.0 N) is found to be the most effective in the process of color development. The sensitivity of the method is from 1.7 to 2.1 times higher, as compared to the conventional Fiske and Subba Row method for the measurements carried out at the end of 15 min at 820 nm and with the highest concentration of H2SO4 (1.0 N); the sensitivity increased 4.8-fold at the end of 24 h. Presence of glucose and sucrose (1-10 mM), NaCl and KCI (5-100 mM), MgCl2 (1-10 mM) and BSA (10 to 500 microg per assay tube) do not interfere either with color development or with OD measurements. The extent of ATP hydrolysis is 1.6 to 3.4% for up to 1 hi, depending upon the concentration of H2SO4 used. Only negligible hydrolysis of G6P is observed under these conditions. These results suggest that the presently modified method is suitable for Pi analysis in the enzyme assays, in the presence of labile phosphate containing substrates.
Тема - темы
Adenosine Triphosphate/chemistry , Carbohydrates/chemistry , Chromogenic Compounds/chemistry , Glucose-6-Phosphate/analysis , Phosphates/analysis , Salts/chemistry , Serum Albumin, Bovine/chemistry , Sulfuric Acids/chemistryРеферат
Arsenic trioxide albumin microspheres (As2O3-BSA-NS) were prepared by using methods of chemical cross-linking. The desirability function (DF), calculated according to the size (0.05). The release experiment in vitro showed that As2O3 in As2O3-BSA-NS was released more slower than pure As2O3. It was concluded that regular As2O3-BSA-NS may be prepared by the methods of chemical cross-linking, which was optimized by orthogonal experimental analysis of different factors, and the microspheres can release As2O3 slowly.
Тема - темы
Arsenicals/chemistry , Cross-Linking Reagents/pharmacology , Delayed-Action Preparations , Drug Carriers/chemistry , Drug Delivery Systems , Microspheres , Oxides/chemistry , Serum Albumin, Bovine/chemistry , Technology, PharmaceuticalРеферат
Para la purificación de albúmina bovina al 30 por ciento se realizaron modificaciones al método de termocoagulación desarrollado industrialmente por Schneider y colaboradores en 1975. Se obtuvo un rendimiento de 26 g/l con un 100 por ciento de pureza determinada por electroforesis en geles de poliacrilamida e inmunoelectroforesis y se utilizaron como control tres albúminas comerciales. En el análisis físicoquímico se tuvieron en cuenta los valores de ph, concentración de proteínas, sodio y cloruro de sodio, contenido de pigmentos hemáticos y cantidad de agregados moleculares determinado por cromatografía de filtración en gel. Para los ensayos inmunohematológicos nos guiamos por las normativas internacionales para el uso de la seroalbúmina bovina. En todos los casos la albúmina LABIOFAM cumplió con los controles de calidad establecidos para su uso en el diagnóstico serológico de los Servicios de Transfusión y Bancos de Sangre.
Тема - темы
Humans , Serum Albumin, Bovine/physiology , Serum Albumin, Bovine/immunology , Serum Albumin, Bovine/chemistry , Serum Albumin, Bovine , Blood Banks , Blood Transfusion , Electrocoagulation/economics , Electrocoagulation/methods , Electrocoagulation , Serologic Tests/methods , Electrophoresis , Immunoelectrophoresis , Quality ControlРеферат
Monoclonal antibodies (MAbs) to quinine conjugated to a carrier protein were produced. Quinine was converted into a hemisuccinate prior to covalently linked to bovine serum albumin (BSA) by reacting with N,N'-disuccinimidyl carbonate (DSC). Coupling ratio of quinine-BSA was 13:1 calculated by spectrophotometry and 14:1 by calculation from quinine standard curve. This immunogen was used for both monoclonal antibody production and for screening test, indirect ELISA. The specificity of quinine-BSA MAbs was examined by checking the cross reactivity with BSA and the structurally related antimalarial drug, mefloquine. Six MAbs belonging to IgG1 were obtained. These MAbs slightly reacted with mefloquine-BSA because of closely related structure of mefloquine to quinine and similar conjugate preparation procedure used for conjugation. One selected MAb against quinine-BSA, showed higher reactivity with blood samples from patients previously treated with quinine when compared to normal blood. This preliminary test indicated that MAbs obtained may be useful to be used as the probe for detection of quinine in biological fluids.
Тема - темы
Animals , Antibodies, Monoclonal/biosynthesis , Antibody Specificity , Antimalarials/blood , Cross Reactions , Enzyme-Linked Immunosorbent Assay , Female , Humans , Hybridomas , Immunoglobulin G/biosynthesis , Mefloquine/immunology , Mice , Mice, Inbred BALB C , Quinine/blood , Serum Albumin, Bovine/chemistryРеферат
Extent of water vapour adsorption (n1) of gelatin and bovine serum albumin and their mixtures in different proportion respectively has been measured by isopiestic vapour pressure methods at various values of water activity (a1) ranging between zero and unity. Similar measurements have also been carried out with gelatin and BSA coated alumina powder. At a given value of a1, n1 for the protein mixture is found to be significantly less than their ideal value obtained from the additivity rule. Such decrease is probably due to the protein-protein interaction as a result of which some of the water binding sites become unavailable for water vapour adsorption. On the other hand when a protein is mixed with alumina powder, the water vapour adsorption of the protein coated alumina surface at a given water activity is found to be 2 to 3 times larger than its ideal value obtained from the additivity rule. The standard free energy changes for hydration of protein mixtures and protein-coated alumina have been evaluated using Bull equation. The extent of excess hydration of these proteins and their mixtures as well as protein-coated alumina in the presence of excess neutral salts and urea respectively have been evaluated using the isopiestic method. In all cases, the moles of water and solute respectively bound in absolute amount to biopolymers, biopolymer mixtures and protein-coated alumina have been evaluated in the limited range of solute concentrations in the medium. Based on the Gibbs-Duhem equations, a rigorous expression for the standard free energy change for binding of excess solute and solvent to biopolymer have been evaluated with reference to unit solute mole fraction as standard state. Free energies of excess hydration of different biopolymer systems have been evaluated using this equation.
Тема - темы
Aluminum Oxide/chemistry , Gelatin/chemistry , Protein Binding , Serum Albumin, Bovine/chemistry , Surface Properties , Water/chemistryРеферат
The kinetics of adsorption of soluble denatured protein, gelatin has been studied at the alumina-water interface as a function of protein concentration, pH, temperature and ionic strength. The rate of adsorption of gelatin has been compared with rate of adsorption of BSA denatured by 8 M urea or 0.05 M SDS. The initial stage for the adsorption process is diffusion-controlled and the surface diffusion coefficients evaluated from equations of Ward and Tordai and by Bull for globular and denatured proteins are found to be widely different from each other. The kinetic data for gelatin fit into a first order rate equation with two rate constants, k1a and k2a. Using Arrhenius equation, the activation energies delta E1* and delta E2* have been evaluated from the values of k1a and k2a respectively. The corresponding changes in values of enthalpy of activation (delta H*), entropy of activation (delta S*) and free energy of activation (delta G*) have been evaluated using Eyring's equation for absolute reaction rate. It has been found that for both gelatin and denatured BSA, in the first kinetic step delta H1* > T delta S1* and for the second step T delta S2* > delta H2.
Тема - темы
Adsorption , Aluminum Oxide , Gelatin/chemistry , Kinetics , Protein Denaturation , Serum Albumin, Bovine/chemistry , Thermodynamics , WaterРеферат
Binding characteristics of bovine serum albumin-aflatoxin B1 conjugates with high (1:54), medium (2:25) and low (1:9) hapten to carrier molar ratios, to the polystyrene microtiter plates are influenced by the stoichiometry of the hapten (Aflatoxin B1) to the carrier protein (bovine serum albumin). Conjugates with optimal hapten to carrier molar ratios (1:25) showed a better binding capacity to the polystyrene microtiter plate as compared to the conjugates with the high molar ratios in a non-competitive ELISA for aflatoxin B1. Denaturation of the conjugate with molar ratio of 1:54 in order to enhance its binding capacity, however, did not result in any significant improvement.
Тема - темы
Aflatoxin B1/chemistry , Animals , Carrier Proteins/analysis , Cattle , Enzyme-Linked Immunosorbent Assay , Haptens/analysis , Polystyrenes , Protein Binding , Serum Albumin, Bovine/chemistryРеферат
Fluorescence of 1-anilinonaphthalene-8-sulfonate (ANS) is greatly enhanced on its binding to bovine serum albumin (BSA). Fluorimetric titration shows that three ANS molecules bind per BSA molecule. The enhanced fluorescence of BSA-ANS is quenched by eosine (EOS); and one EOS physically displaces one ANS bound to BSA. The enhanced fluorescence of free ANS in the hydrophobic environment of the nonionic surfactant Triton X 100 is also quenched by EOS but by an energy transfer mechanism. The dye fluorescene (FLSN) also quenches the fluorescence of BSA-bound ANS, but by the energy transfer mechanism. The binding region of ANS in BSA has been speculated.
Тема - темы
Anilino Naphthalenesulfonates , Binding, Competitive , Eosine Yellowish-(YS) , Fluoresceins , Fluorescent Dyes , Kinetics , Serum Albumin, Bovine/chemistry , Spectrometry, Fluorescence/methodsРеферат
The adsorption isotherms of different proteins from aqueous solution to the surface of different solids have been compared in the presence of additives such as urea, surfactants and high concentration of various neutral salts. The adsorption isotherms of lysozyme on alumina are not affected much in the presence of 8 M urea showing the rigid structure of lysozyme whereas isotherms of hemoglobin show surface coagulation even in presence of 2 M urea. In presence of 8 M urea, adsorption isotherms of BSA on alumina show two distinct steps. The extent of protein adsorption in the presence of surfactants depends on the nature of surfactants as well as of the underlying surface. The adsorption isotherms of BSA and lysozyme in presence of 2 M concentration of different neutral salts have also been compared with each other. In the presence of denaturants such as NaI and LiCl, the proteins are adsorbed in unfolded beta-conformation whereas in the presence of protein stabilizers such as NaCl, KCl and Na2SO4, amount of protein adsorbed at saturation is zero or extremely small showing that unfolding of proteins at the interface is necessary for initial stage of protein adsorption. The standard free energy change (delta G degrees) per square meter of the surface, signifying relative affinity of adsorption at the state of monolayer saturation, have been calculated. The magnitude of standard free energy of transfer (delta G degrees B) of one mole of protein to the surface in presence of all the additives was found close to 40 kJ/mole.
Тема - темы
Absorption , Aluminum Oxide , Barium Sulfate , Hemoglobins/chemistry , Muramidase/chemistry , Protein Denaturation , Salts , Serum Albumin, Bovine/chemistry , Silicon Dioxide , Surface-Active Agents , UreaРеферат
X-band electron paramagnetic resonance (epr) spectra of the binary systems, BSA-copper(II) (1:1 and 2:1), and the ternary systems, BSA-Cu(II)-aminoacid (1:1:1), are described. In the binary system, two distinct epr features have been observed. One of the features (towards the low pH), showing broad and overlapping epr signals, has been attributed to non-specific bonding of copper(II) to the albumin and other feature (towards higher pH), showing sharp intense epr signals, has been attributed to the specific bonding. The change from non-specific to specific binding is favoured by increase in pH as well as by increase in protein concentration. Specific binding of copper(II) in BSA-Cu(II) has been suggested to be similar to that in HSA-Cu(II). Spectra of BSA-Cu(II)-aminoacid (1:1:1) show simultaneous presence of binary BSA-Cu(II) and ternary BSA-Cu(II)-aminoacid.
Тема - темы
Amino Acids/metabolism , Binding Sites , Copper/metabolism , Electron Spin Resonance Spectroscopy/methods , Humans , Protein Conformation , Serum Albumin/chemistry , Serum Albumin, Bovine/chemistryРеферат
The interaction of gossypol with bovine serum albumin, human serum albumin and n-bromosuccinimide-modified bovine serum albumin has been followed by fluorescence quenching measurements. The presence of a high affinity site (association constant K = 2.2 x 10(6) M-1) for gossypol on bovine serum albumin and human serum albumin is indicated. The stoichiometry of binding for the high affinity site was evaluated using Job's method of continuous variation, thereby suggesting the formation of 1:1 complex. Modification of the tryptophan residues on bovine serum albumin does not affect the binding of gossypol to either high or low affinity site of albumin.