Showing papers on "Human serum albumin published in 1980"
TL;DR: Structural alterations of albumin, their dependence on concentration and the role of free --SH groups at thermal denaturation, as well as the reversibility of thermally induced structural changes, were studied.
Abstract: Structural alterations of albumin, their dependence on concentration and the role of free --SH groups at thermal denaturation, as well as the reversibility of thermally induced structural changes, were studied. Application of various physical methods provides information on a series of structural parameters in a major concentration range. Apart from changes of the helix content, heat treatment gives rise to beta structures which are amplified on cooling and which are correlated with the aggregation of albumin. With rising temperature and concentration the proportion of beta structures and aggregates increases. At degrees of denaturation of up to 20% complete renaturation is possibly in every case. The structure content is concentration-dependent even at room temperature. It may be that intermolecular interactions induce additional alpha-helix structures which are less stable, however, than the ones stabilized by intramolecular interactions. Unfolding of the pocket containing the free --SH group of cysteine-34 enables disulphide bridges to be formed leading to stable aggregates and irreversible structural alterations. Through binding of N-ethymaleimide to free --SH groups, which blocks the formation of disulphide bridges, it is possible to prevent aggregation and irreversible conformational changes. At temperatures below 65--70 degrees C, oligomers are formed mainly via intermolecular beta structures.
228 citations
TL;DR: In this paper, the pH dependence of warfarin binding to human serum albumin has been studied by circular dichroism, fluorescence, and equilibrium dialysis, showing that albumin complexes at low drug to protein ratios parallel the neutral to base transition, occurring in the protein over the pH range 6 to 9.
215 citations
TL;DR: The results obtained indicate that methaemalbumin is formed in a two-stage, single-intermediate process, consistent with a general binding mechanism for albumin in which intermediate formation is followed by an entropy-controlled internalization of the ligand.
Abstract: The interaction of human serum albumin with monomeric haemin has been investigated by detailed kinetic analysis in dimethyl sulphoxide/water (3:5, v/v). The results obtained under conditions of albumin saturation of haemin and under pseudo-single turnover conditions indicate that methaemalbumin is formed in a two-stage, single-intermediate process. The initial association between the haemin and human serum albumin is a chemically controlled process (k1 = 1.7 X 10(5) mol-1 . s-1 . dm3 at 24 degrees C); the variation of K1 with pH exhibited a well defined pK of 5.9. The overall equilibrium constant, calculated by using microscopic rate constants, is 1.1 (+/- 0.5) X 10(8) mol-1 at 24 degrees C. The data and conclusions are consistent with a general binding mechanism for albumin in which intermediate formation is followed by an entropy-controlled internalization of the ligand.
143 citations
TL;DR: There is little or no interaction of Cibacron Blue and the bilirubin-binding sites of albumins from rabbit, horse, bovine or sheep sera, although some interaction occurs between CibACron Blueand the fatty acid- binding sites of these proteins.
Abstract: The interaction of Cibacron Blue F3G A-Sepharose 4B with several serum albumins was studied. Although all albumins used were fond to bind to this adsorbent, human serum albumin was bound to a far greater extent than were the others. From the results of competition experiments and n.m.r. studies of Cibacron Blue and/or bilirubin binding to human serum albumin it is proposed that the mechanism of the interaction between human serum albumin and cibacron Blue is consistent wit Cibacron Blue binding to bilirubin-binding sites. In contrast with these findings with human serum albumin, there is little or no interaction of Cibacron Blue and the bilirubin-binding sites of albumins from rabbit, horse, bovine or sheep sera, although some interaction occurs between Cibacron Blue and the fatty acid-binding sites of these proteins. Structural analogues of Cibacron Blue have been used to investigate the binding of albumins to these ligands.
140 citations
TL;DR: Scatchard analysis revealed that human serum albumin bound to a homogeneous population of receptors with an affinity in the order of 10(7) liters/mol and that the average bacterial cell carried more than 80,000 binding sites.
Abstract: A total of 297 bacterial strains belonging to 27 species was tested for quantitative uptake of radiolabeled human serum albumin. Specific binding sites with high affinity for human serum albumin were found exclusively in group C and G streptococci. The albumin binding was found to be a time-dependent, saturable, and displaceable process which obeyed simple kinetic equations. Scatchard analysis revealed that human serum albumin bound to a homogeneous population of receptors with an affinity in the order ot 10(7) liters/mol and that the average bacterial cell carried more than 80,000 binding sites. The albumin receptor is a heat-stable component susceptible to proteolytic digestion. It has a surface localization separate from the receptors for immunolgobulin G, fibrinogen, aggregated beta 2-microglobulin, and haptoglobin. In individual strains, albumin reactivity was also detected independently of these other types of interactions with human proteins.
97 citations
Journal Article•
TL;DR: It has been shown that diazepam, digitoxin and warfarin independently bind to albumin and can conveniently be used as markers of three separate, discrete binding sites on albumin, and results suggest the presence of more than the three binding sites for drugs on the albumin surface studied.
Abstract: Human serum albumin can be immobilized in spherical, macroporous microparticles of polyacrylamide of about 1 µm in diameter with retention of its native properties. It has been shown that diazepam, digitoxin and warfarin independently bind to albumin and can conveniently be used as markers of three separate, discrete binding sites on albumin. A simple technique has been devised by which the capacity of about 140 drugs and other compounds to affect the binding of the radioactively labeled markers has been studied. Some drugs, e.g. antirheumatic drugs of the isopropionic acid-type, some antidiabetic agents, penicillin derivatives, benzodiazepines, tryptophan, dansylsarcosine, and suiphobromophthalein efficiently displace diazepam. Other drugs, e.g. , some diuretics, sulpha drugs, phenytoin, salicylic acid and butazone derivatives, azapropazoe, bilirubin, and dansylamide displace warfarin. Displacement of digitoxin is less common. In some cases the binding of the markers is improved, e.g. , tamoxifen increases the binding of warfarin. Both competitive and allosteric mechanisms are responsible for the changed binding of the markers. Some results suggest the presence of more than the three binding sites for drugs on the albumin surface studied with diazepam, digitoxin and warfarin.
ACKNOWLEDGMENTS The skillful technical assistance from Mr. Borje Berg, Miss Solveigh Hoglund, Mrs. Elisabeth Tidare and Mrs. Linnea Wallsten is gratefully acknowledged. We also thank the manufacturers and their Swedish representatives for supplying us with the drugs used.
96 citations
TL;DR: Hemopexin is able to compete effectively with albumin for coproporphyrin I or III only at low molar ratios of the two proteins and seems unlikely to bind a significant portion of these porphyrins at the molar ratio of hemopexIn and albumin found in human serum.
89 citations
TL;DR: It was shown, with a two state conformational model for albumin, that the pH dependences of molar ellipticity of the diazepam-albumin complex and of the free concentration ofdiazepam are linked and it was demonstrated that the N-B transition of albumin is involved in the pH dependent binding of Diazepam.
81 citations
TL;DR: It is unlikely that the protein bound fraction of the administered 'free' drug will serve as a therapeutically useful 'drug resevoir' due to the apparent irreversibility of the protein/195mPt-cisplatin complex.
81 citations
TL;DR: It was found that both compounds reacted very rapidly with plasma proteins to form covalently bound derivatives, and the protein binding of thromboxane was more pH-sensitive than the binding of prostaglandin H2.
Abstract: The present report describes the interactions of human plasma proteins with the unstable endoperoxide, prostaglandin H2 and thromboxane A2, generated by incubation of platelets with prostaglandin H2 or arachidonic acid. It was found that both compounds reacted very rapidly with plasma proteins to form covalently bound derivatives. The major reacting plasma protein was human serum albumin. Depending on conditions, 20-40% of added prostaglandin H2 and 50-80% of generated thromboxane were bound to proteins. This reaction of both prostaglandin H2 and thromboxane A2 prevents their detection by classical analytical methods. The protein binding of thromboxane was more pH-sensitive than the binding of prostaglandin H2. The reactions cause reduced levels of both endoperoxide and thromboxane B2 in suspensions of washed platelets using human serum albumin as compared to buffer. It was also shown that the half-life of prostaglandin H2 was considerably reduced in the presence of albumin.
64 citations
Journal Article•
TL;DR: The four antiinflammatory drugs azapropazone, flurbiprofen, ibuprofen and naproxen all bind very strongly to serum albumin with association constants, Ka, in good agreement with those obtained with equilibrium dialysis.
Abstract: The four antiinflammatory drugs azapropazone, flurbiprofen, ibuprofen, and naproxen all bind very strongly to serum albumin with association constants, Ka, of 5.0 x 105, 5.0 x 106, 1.3 x 106, and 1.8 x 106 M-1, respectively. The binding constants were determined with albumin immobilized in microparticles and were shown to be in good agreement with those obtained with equilibrium dialysis. Ibuprofen, flurbiprofen, and naproxen are primarily bound to the diazepam site on the albumin molecule as shown in interaction studies with albumin immobilized in microparticles. This site is shared with, e.g., some antidiabetic agents and benzodiazepines. Azapropazone is primarily bound to the warfarin site, to which also other coumarin derivatives and, e.g., phenytoin and bilirubin are bound. The antiinflammatory drugs studied have small distribution volumes and low free fractions in plasma, which means that displacement from their binding sites may be of pharmacokinetic significance.
Journal Article•
TL;DR: These experiments demonstrate that the channels produced in erythrocyte ghost membranes by large C doses have a long, although finite, life-span and their effective diameter is al least 55 A on the basis of ovalbumin and hemoglobin release, and not more than 150 A, since serum albumin was not released.
Abstract: To evaluate the life-span and size of trans-membrane channels in complement (C) treated membranes, resealed erythrocyte ghosts containing trapped native protein markers, as well as residual hemoglobin, were treated with anti-Forssman antibody and large doses of guinea pig C. Ovalbumin and hemoglobin were released slowly through the channels so produced, whereas human serum albumin was not. Release of hemoglobin was not blocked by extracellular bovine serum albumin. Release of hemoglobin continued for at least 72 hr at 4 degrees C. Semi-logarithmic plots of ovalbumin or hemoglobin release showed gradual diminution of the rate constant, which indicates slow loss of channels during the experimental period. These experiments demonstrate that the channels produced in erythrocyte ghost membranes by large C doses have a long, although finite, life-span. Their effective diameter is al least 55 A on the basis of ovalbumin and hemoglobin release, and not more than 150 A, since serum albumin was not released. However, an upper limit of 100 A would be more reasonable in light of electronmicroscopic observations by others. These results are compatible with the doughnut model.
TL;DR: It is concluded that reaction with the buried tryptophan involves the initial second-order formation of a complex in which the quencher is located at the mouth of a hydrophobic fold, and that this is followed by a first-order conformational change which allows interaction to occur between theQuencher and the tryPTophan.
Journal Article•
TL;DR: A procedure has been developed whereby small amounts of protein--specifically human serum albumin and immunoglobulin G--can be labeled with Tc-99m, which is satisfactory for labeling human serumalbumin, normal goat immunoglobeulin G, and goat anti-carcinoembryonic antigen immunoglOBulin G.
Abstract: A procedure has been developed whereby small amounts of protein--specifically human serum albumin and immunoglobulin G--can be labeled with Tc-99m. Artifactual problems associated with electrolytic and stannous chloride labeling procedures are virtually eliminated. The procedure is satisfactory for labeling human serum albumin, normal goat immunoglobulin G, and goat anti-carcinoembryonic antigen immunoglobulin G.
TL;DR: The locations of five major antigenic sites of bovine serum albumin are predicted and confirmed by synthesis and the major structural locations responsible for the immunochemical cross-reaction between these two albumins are identified.
TL;DR: There was a correlation between the binding of radiolabled human proteins to the bacterial strains and the effect of human proteins on the partition of the bacteria in the phase systems, suggesting that these types of bacteria-protein interactions may play an important role in modulating host-parasite relationships.
Abstract: Four strains of gram-positive cocci with different combinations of positive binding of human proteins were investigated with respect to changes in physicochemical surface properties after specific protein binding. Staphylococcus aureus Cowan I, two group A beta-hemolytic streptococci, and one group G streptococcal strain were studied; they represented three different combinations of reactivity for human serum albumin, human immunoglobulin G, and fibrinogen. Using single-tube partition of bacterial cells in a dextran-polyethylene glycol system of constant polymer concentration but varying ionic compositions, it was possible to detect changes in the partition of bacteria after specific protein binding. There was a correlation between the binding of radiolabled human proteins to the bacterial strains and the effect of human proteins on the partition of the bacteria in the phase systems. Thus, the specific binding of proteins to the bacteria changes their physicochemical surface properties. These types of bacteria-protein interactions may play an important role in modulating host-parasite relationships.
TL;DR: Two antigens, both containing tolyl groups, were compared for ability to detect IgE antibodies in workers hypersensitive to toluene diisocyanate, and the significance of this binding to human serum albumin‐coated control discs than did sera from non‐sensitive workers is discussed.
Abstract: Summary
Two antigens, both containing tolyl groups, were compared for ability to detect IgE antibodies in workers hypersensitive to toluene diisocyanate. One antigen, formed by reaction of p-tolyl isocyanate with human serum albumin, detected antibodies in each of ten hypersensitive workers. A second tolyl antigen, formed by reaction of p-toluoyl chloride and human serum albumin, and therefore lacking isocyanate linkages, detected antibodies in seven of the ten workers. In RAST assays, sera from toluene diisocyanate-sensitive workers demonstrated higher binding to human serum albumin-coated control discs than did sera from non-sensitive workers. The significance of this binding in calculating tolyl-reactive antibody titres is discussed.
TL;DR: The number of binding sites and the dissociation constants were determined for the binding of bilirubin to human liver ligandin and to human serum albumin and the results are interpreted in terms of kinetically stable conformational isomers of ligand in induced by bilirUBin or by glutathione.
TL;DR: Results indicate that serum HA interferes in vitro with certain anticancer agents in terms of biological activity and clinical effectiveness and may be a major factor governing the pharmacology of Type I antic cancer agents in man.
Abstract: The influence of human serum albumin (HA) on the biological effects of 13 chemotherapeutic agents was studied in vitro in the human leukaemia cell line MOLT-3. On the basis of changes in biological activity influenced by HA, these drugs may be divided into three types. Type I agents include cis-diamminedichloroplatinum (II), 4'-(9-acridinylamino)methanesulphon-m-anisidide, neocarzinostatin, nitrogen mustard, adriamycin, daunorubicin and mitomycin C--drugs whose biological activities are reduced in the presence of HA. The biological activities of Type II drugs (cytosine arabinoside, fluorouracil and actinomycin D) are not influenced by HA. The biological activities of Type III drugs (bleomycin, vincristine and vinblastine) are increased in the presence of HA. These results indicate that serum HA interferes in vitro with certain anticancer agents in terms of biological activity and, probably, clinical effectiveness. HA-drug interaction may be a major factor governing the pharmacology of Type I anticancer agents in man.
TL;DR: A continuous frontal analysis chromatographic method was developed for studying the simultaneous binding of two drugs or ligands with an immobilized macromolecule and the mutual inhibitory effect on the binding of one drug of the presence of the other was directly shown to be due to displacement of the bound drug from HSA by the other.
TL;DR: It is postulate that the level of conjugation is the critical parameter controlling the blood clearance in rabbits, and highly conjugated111In-labeled AAHSA (0.9 DTTA/HSA) showed accelerated clearance at 24 and 48 hours compared to lightly conjugate protein.
Abstract: A new bifunctional chelating agent, N′-(p-diazoniumbenzyl)-N,N N″,N″-diethylenetri-aminetetraacetic acid (DTTA) was synthesized. The compound as coupled to methyl p-hydroxybenzimidate and the resulting azoimidate was attached to lysine residues of monomeric human serum albumin (HSA) via the amidination reaction. Blood clearnace of111In-labelled DTTA conjugated to HSA (AAHSA) in rabbits was biphasic. The first phase has a clearance indistinguishable from that of125I-labeled HSA. During the second phase, the111In-labeled AAHSA was cleared more rapidly so that between 24 hours and 48 hours the percent of the injected dose of111In-labeled AAHSA in the blood was significantly lower than that of125I-labeled HSA. Highly conjugated111In-labeled AAHSA (0.9 DTTA/HSA) showed accelerated clearance at 24 and 48 hours compared to lightly conjugated protein (<0.9 DTTA/HSA). As a result we postulate that the level of conjugation is the critical parameter controlling the blood clearance.
TL;DR: Human serum albumin (HSA) is found to contain one primary binding site for medium chain fatty acids which is competitive with the binding of N-acetyl-L-tryptophan, and the secondary binding sites formedium chain fatty acid are found to be the same general region as the primarybinding site.
Journal Article•
TL;DR: It was shown that valproate, with its high therapeutic plasma concentration, would increase the free fraction of phenytoin by 100%.
Abstract: The binding of valproate and phenytoin to human serum proteins has been studied qualitatively and quantitatively by equilibrium dialysis and with albumin immobilized in microparticles. Albumin was shown to be the only protein significantly binding valproate in serum. Valproate is bound to two sites on the albumin molecule, the diazepam and warfarin sites, with the association constants, Ka, 3.1 x 104 M-1. Phenytoin is bound primarily only to one site, (Ka 1.7 x 104 M-1), which is identical to the second valproate site, i.e., the warfarin one. A theoretical evaluation of the possible interaction between valproate and phenytoin in vivo was made. It was shown that valproate, with its high therapeutic plasma concentration, would increase the free fraction of phenytoin by 100%. On the other hand, phenytoin at therapeutic concentrations would not significantly displace valproate. These theoretical calculations were confirmed by the experimental results obtained with sera from epileptic patients treated with phenytoin. The binding of phenytoin was markedly decreased when valproate was added to the sera in vitro, while the binding of valproate was not significantly impaired.
TL;DR: The rates of chemical degradation of chloroethylnitrosoureas in serum are significantly higher than in aqueous buffer at the same pH and temperature and rate enhancement is shown to be produced by a non-specific protein mediated chemical reaction that involves the formation of a protein-chloroethylNitrosourea (CENU) complex.
TL;DR: The retention volume of a ligand, injected onto a size exclusion chromatographic column and eluted by a macromolecular complexing solution, is theoretically analysed for evaluating the binding between the solute and the macromolescule.
Abstract: The retention volume of a ligand, injected onto a size exclusion chromatographic column and eluted by a macromolecular complexing solution, is theoretically analysed for evaluating the binding between the solute and the macromolecule. The binding of D- and L- tryptophan to human serum albumin is given as an example, and the separation of these enantiomers is then achieved
TL;DR: It is concluded that this important binding site of HSA depends on the tertiary structure of the albumin, and this highly reactive tyrosine residue is specifically involved in the indole and benzodiazepine binding site.
TL;DR: A mechanism for uptake of 125 I-PVP by a combination of fluid-phase and adsorptive endocytosis from the flagellar pocket of the trypanosome is proposed.
TL;DR: The experimentally obtained relaxation constants are best explained by the existence of 5 equivalent low affinity binding sites for warfarin on the HSA molecule, each capable of conversion into a high affinity site.
Abstract: We have studied the binding of warfarin to human serum albumin (HSA) with the stopped-flow method. At 37 degrees C the rate constant for the velocity of dissociation of the stable warfarin-HSA complex is 10 S-1 (t50% = 0.07 s). Concentration and temperature dependent association constants for warfarin binding to HSA have been measured (2.5 x 10(5) M-1 S-1 at 6 degrees C, 9.8 x 10(5) M-1 S-1 at 22 degrees C and 15.3 x 10(5) M-1 S-1 at 37 degrees C). Our experimentally obtained relaxation constants are best explained by the existence of 5 equivalent low affinity binding sites for warfarin on the HSA molecule, each capable of conversion into a high affinity site. The measured energy of activation for this conversion is 57.5 kJ M-1.
TL;DR: The nature of the Ni(II)-binding site of the NH2-terminal tripeptide segment of human albumin: L-aspartyl-L-alanyl- L-histidine-N-methyl amide (AAHNMA) is reported as deduced by 13C- and 1H-nmr spectroscopy, which confirms the coordination of these two protons.
Abstract: Recent studies have shown that Ni(II) in human blood serum is bound to albumin and the binding site is located at the NH2-terminus of the protein. In this article, the nature of the Ni(II)-binding site of the NH2-terminal tripeptide segment of human albumin: L-aspartyl-L-alanyl-L-histidine-N-methyl amide (AAHNMA) is reported as deduced by 13C- and 1H-nmr spectroscopy. The 13C spectrum shows that the Ni(II) complex is in slow exchange on the nmr time scale, and resonances for Ni(II)–peptide complex and metal-free peptide are observed clearly in the pH range 6.4 to 9.1. The Asp COO− carbon is most affected by Ni(II) binding. The imidazole ring system also shows large variation. Furthermore, the results implicate the involvement of the NH2 group. The introduction of Ni(II) ion into the solution containing peptide causes profound changes in the 1H-nmr spectra in the pH range 6.4 to 9.1. Most significantly, there is a complete disappearance of Ala and His N—H protons which confirm the coordination of these two...