Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0393754 (HSA)
 2,996 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The binding of several different categories of small molecules to bovine (BSA) and human (HSA) serum albumins has been studied for many years through different spectroscopic techniques to elucidate details of the protein structure and binding mechanism. In this work we present the results of the study of the interactions of BSA and HSA with the anionic sodium dodecyl sulfate (SDS), cationic cethyltrimethylammonium chloride (CTAC) and zwitterionic N-hexadecyl-N,N-dimethyl-3-ammonium-1-propanesulfonate (HPS) monitored by fluorescence spectroscopy of the intrinsic tryptophans at pH 5.0. Similarly to pH 7.0 and 9.0, at low concentrations, the interaction of BSA with these surfactants shows a quenching of fluorescence with Stern-Volmer quenching constants of (1.1+/-0.1)x10(4) M(-1), (3.2+/-0.1)x10(3) M(-1) and (2.1+/-0.1)x10(3) M(-1) for SDS, HPS and CTAC, respectively, which are associated to the 'effective' association constants to the protein. On the interaction of these surfactants with HSA, an opposite effect was observed as compared to BSA, i.e., an enhancement of fluorescence takes place. For both proteins, at low surfactant concentrations, a positive cooperativity was observed and the Hill plot model was used to estimate the number of surfactant binding sites, as well as the association constants of the surfactants to the proteins. It is worthy of notice that the binding constants for the surfactants at pH 5.0 are lower as compared to pH 7.0 and 9.0. This is probably due to fact that the protein at this acid pH is quite compact reducing the accessibility of the surfactants to the hydrophobic cavities in the binding sites. The interaction of myristic acid with both proteins shows a similar fluorescence behaviour, suggesting that the mechanism of the interaction is the same. Recently published crystallographic studies of HSA-myristate complex were used to perform a modelling study with the aim to explain the fluorescence results. The crystallographic structure reveals that a total of five myristic acid molecules are asymmetrically bound in the macromolecule. Three of these sites correspond to higher affinity ones and correlate with high association constants described in the literature. Our models for BSA and HSA with bound SDS suggest that the surfactant could be bound at the same sites as those reported in the crystal structure for the fatty acid. The differences in tryptophan vicinity upon surfactant binding are explored in the models in order to explain the observed spectroscopic changes. For BSA the quenching is due to a direct contact of a surfactant molecule with the indole of W131 residue. It is clear that the binding site in BSA which is very close, in contact with tryptophan W131, corresponds to a lower affinity site, explaining the lower binding constants obtained from fluorescence studies. In the case of HSA the enhancement of fluorescence is due to the removal of static quenching of W214 residue in the intact protein caused by nearby residues in the vicinity of this tryptophan.
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PMID:Interaction of bovine (BSA) and human (HSA) serum albumins with ionic surfactants: spectroscopy and modelling. 1182 11

A new assay for the screening of hypochlorite/hypochlorous acid (XOCl) scavengers, based on the reversed-phase high performance liquid chromatographic analysis of human serum albumin (HSA, 0.2% in 100 mM sodium phosphate, pH 7), before and after oxidation by XOCl (1.6 mM), was developed. XOCl induced a significant decrease of the area under the chromatographic peak of HSA at 280 nm due to the oxidation of the aromatic amino acids tryptophan and tyrosine, as suggested by the literature and by the chromatographic analyses and the electrochemical study performed here. The assay was validated by testing known XOCl scavengers such as ascorbic acid, cysteine, glutathione, S-methylglutathione and alpha-lipoic acid and other antioxidants such as carnosine and chlorogenic acid, which inhibited the oxidation of HSA. Quantitative activities were calculated using an original formula based on the changes of the area of the albumin peak. Electrochemical data collected here in a homogeneous medium showed that the anodic potentials of the antioxidants tested are less positive (ascorbic acid, chlorogenic acid and cysteine) or similar (alpha-lipoic acid) compared with those of the aromatic residues (tryptophan and tyrosine) of HSA oxidized by XOCl. However, as expected, carnosine, glutathione and S-methylglutathione were inactive at a glassy-carbon, gold or platinum electrode.
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PMID:Development of a new assay for the screening of hypochlorous acid scavengers based on reversed-phase high-performance liquid chromatography. 1222 98

The effect of column temperature on enantiomeric resolutions of tryptophan, warfarin and ketoprofen was investigated on bovine and human serum albumin (BSA and HSA) stationary phases, which were synthesized with s-triazine as the activator. It was observed that the entropy change made a great contribution to the separation of those enantiomers on albumin chiral stationary phases. The column temperature for the maximal resolution of tryptophan on the BSA stationary phase prepared by this method was about 35 degrees C, which was not 24 degrees C as reported for the BSA stationary phase synthesized with glutaric dialdehyde as the activator. This results may come from the different conformation of the immobilized BSA and HSA due to the different coupling methods used. On the other hand, it was indicated that the resolution of enantiomers on beta-CD chiral stationary phase was mainly contributed from the change of enthalpy, which means the resolution of chiral solutes on albumin and beta-CD stationary phases has different thermodynamic behaviors.
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PMID:[The effect of temperature on the enantiomeric resolutions on albumin and beta-cyclodextrin chiral stationary phases]. 1254 37

Binding of chlorpromazine (CPZ) and hemin (Hmn) to human (HSA) and bovine (BSA) serum albumin was studied by fluorescence quenching technique. Intrinsic fluorescences of BSA and HSA were measured by selectively exciting their tryptophan residues. Gradual quenching was observed by titration of both proteins with CPZ and Hmn. CPZ is a widely used anti-psychosis drug that causes severe side effects and strongly interacts with biomembranes, both in its lipidic and proteic regions. CPZ also interacts with blood components, influences bioavailability, and affects the function of several biomolecules. Albumin plays an important role in the transport and storage of hormones, ions, fatty acids and others substances, including CPZ, affecting the regulation of their plasmatic concentration. Hmn is an important ferric residue of hemoglobin that binds within the hydrophobic region of albumin with great specificity. Hmn added to HSA and BSA solutions at a molar ratio of 1:1 quenched about half of their fluorescence. Stern-Volmer plots obtained from experiments carried out at 25 and 35 degrees C showed the quenching of fluorescence of HSA and BSA by CPZ to be a collisional phenomenon. Hmn quenches fluorescence by a static process, which specifically indicates the formation of a complex. Our results suggest the prime binding site for CPZ and Hmn on both HSA and BSA to be near tryptophan residues.
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PMID:Chlorpromazine interactions to sera albumins. A study by the quenching of fluorescence. 1508 40

The 19F NMR spectrum of triflupromazine hydrochloride (TFZ) in a buffer solution (pH 6.8) showed a single sharp signal of the TFZ CF3 group at 13.5 ppm from the external trifluoroacetic acid. The addition of 1 mM HSA or BSA to the sample solution caused a split of the CF3 signal into two broadened signals shifted to slightly lower (0.2 ppm) and higher (0.7 ppm) fields, respectively, from the original position. Denaturation of the albumins by guanidine hydrochloride (3M) restored the two broadened signals to a slightly broadened single signal, indicating that TFZ has at least two binding sites on HSA and BSA, respectively. From the competitive binding 19F NMR experiments using Warfarin (Site-I ligand), l-tryptophan (Site-II ligand), NaCl, and oleate, the signal at high field was assigned to the TFZ bound to Site II. Comparison of the signal intensity revealed that the affinity of TFZ for Site II on HSA was considerably higher than that on BSA. The low-field signal could be identified as a weight-averaged signal between nonspecifically bound TFZ to HSA (BSA) and free TFZ in the water phase. In the presence of physiological concentrations of NaCl, major binding of TFZ to HSA and BSA was considered to be nonspecific. The present work indicates that 19F NMR is very useful for obtaining important detailed information regarding the binding of fluorinated drugs to serum albumins.
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PMID:19F NMR spectroscopic study on the binding of triflupromazine to bovine and human serum albumins. 1549 37

Multiple binding sites for anaesthetics in HSA (human serum albumin) make solution studies difficult to interpret. In the present study, we expressed the wild-type HSA domain 3 (wtHSAd3), a peptide with two known anaesthetic binding sites in a yeast expression system. We also expressed a site-directed mutant of domain 3 (Y411Wd3). The stability and secondary structure of the constructed fragments were determined by HX (hydrogen-tritium exchange) and CD spectroscopy. The binding of two general anaesthetics, 2-bromo-2-chloro-1,1,1-trifluoroethane and propofol, to wtHSAd3 and Y411Wd3 was determined using isothermal titration calorimetry, HX and intrinsic tryptophan fluorescence quenching. Although the expressed fragments are less stable than intact wtHSA as indicated by both CD and HX, they retain the secondary structure and anaesthetic-binding characteristics of an intact HSA molecule, but with fewer binding sites. Y411Wd3 had decreased affinity for propofol but not for 2-bromo-2-chloro-1,1,1-trifluoroethane, consistent with steric hindrance. Retention of structural features and anaesthetic binding properties with fewer binding sites in this truncated protein provide feasibility for using scaled-down models of otherwise intractable systems to gain an understanding of anaesthetic binding requirements and binding-stability relationships.
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PMID:Truncated human serum albumin retains general anaesthetic binding activity. 1563 93

The interactions between riboflavin (RF) and human and bovine serum albumin (HSA and BSA) were studied by using absorption and fluorescence spectroscopic methods. Intrinsic fluorescence emission spectra of serum albumin in the presence of RF show that the endogenous photosensitizer acts as a quencher. The decrease of fluorescence intensity at about 350 nm is attributed to changes in the environment of the protein fluorophores caused by the ligand. The quenching mechanisms of albumins by RF were discussed. The binding constants and binding site number were obtained at various temperatures. The distance between albumins and RF in the complexes suggests that the primary binding site for RF is close to tryptophan residue (Trp214) of HSA and Trp212 of BSA. The hydration process of albumins has also been discussed.
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PMID:Spectroscopic studies on the interaction between riboflavin and albumins. 1653 Apr 68

Mechanism of interaction of non-steroidal anti-inflammatory drugs, celecoxib and valdecoxib with human serum albumin has been studied using fluorescence spectroscopic technique. There was only one high affinity site on serum albumin for both the drugs with association constants of the order of 10(4) in the case of celecoxib and 10(5) in the case of valdecoxib. Thermodynamic parameters for the binding indicated that hydrogen bonding interactions are predominantly involved in the binding of these drugs to human serum albumin. Binding studies in the presence of hydrophobic probe, 1-anilinonaphthalene-8-sulfonate (ANS) suggested that the mode of interaction of drugs and ANS with HSA is different and hydrophobic interactions are not primarily involved in the binding. Studies carried out in the presence of site-specific probe showed that drugs are bound at site II and phenolic oxygen of (411)Tyr is involved in binding. Stern-Volmer analysis of the quenching data indicated that predominantly static quenching mechanism is operative and the tryptophan residues of albumin are fully accessible to celecoxib and only partially accessible to valdecoxib. The presence of salt caused a decrease in the association constant and significant increase in the concentration of free drug.
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PMID:Reversible binding of celecoxib and valdecoxib with human serum albumin using fluorescence spectroscopic technique. 1660 Jun 20

The noncovalent binding of selected phenolic compounds (chlorogenic-, ferulic-, gallic acid, quercetin, rutin, and isoquercetin) to proteins (HSA, BSA, soy glycinin, and lysozyme) was studied by an indirect method applying the quenching of intrinsic tryptophan fluorescence. From the data obtained, the binding constants were calculated by nonlinear regression (one site binding; y = Bx/k + x). It has been reported that tannins inhibit human salivary amylase and that these complexes may reduce the development of cariogenic plaques. Further, amylase contains two tryptophan residues in its active site. Therefore, in a second part of the study involving 31 human subjects, evidence was sought for noncovalent interactions between the phenols of green tea and saliva proteins as measured by the fluorescence intensity. Amylase activity was determined before and after the addition of green tea to saliva of 31 subjects. Forty percent of the subjects showed an increase in amylase activity contrary to studies reporting only a decrease in activity. The interactions of tannin with amylase result in a decrease of its activity. It still remains to be elucidated why amylase does not react uniformly under conditions of applying green tea to saliva. Further, in terms of using phenols as caries inhibitors this finding should be of importance.
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PMID:Determining the binding affinities of phenolic compounds to proteins by quenching of the intrinsic tryptophan fluorescence. 1683 69

Ferutinin is a potent phytoestrogen extracted from plants of the genus Ferula. The biological activity of this sesquiterpene is associated with the esterification of p-hydroxybenzoic acid with the daucane alcohol, jaeschkeanadiol. A HPLC method was developed to investigate the stability of ferutinin in acidic and basic solutions (pH 1.5 and 9.0, respectively), in buffer (pH 7.4) as well as in serial dilutions of albumin and in human plasma. The degradation of ferutinin was relatively slow at physiological pH 7.4 compared with low or high pH. Ferutinin was fully stable in human plasma as well as in albumin solution and the stability increased with albumin concentration. The binding of ferutinin to albumin was investigated by fluorescence spectroscopy. Ferutinin decreased the fluorescence of HSA and that of the only tryptophan residue located in domain IIA. As a result of the interaction between ferutinin and albumin, the binding of bilirubin decreased. The stability of ferutinin in plasma is attributable to ferutinin-albumin binding.
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PMID:Ferutinin stability in human plasma and interaction with human serum albumin. 1805 Feb 64


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