Showing papers on "Human serum albumin published in 1971"

Effect of free fatty acids on binding of drugs by bovine serum albumin, by human serum albumin and by rabbit serum

Abstract: Do plasma free fatty acids inhibit the binding of other ligands by serum albumin, and if so, at what serum FFA concentration does this effect become manifest? To investigate these questions bovine serum albumin (BSA) and human serum albumin (HSA) were prepared with either 7, 3.5 or l0.05 mol of palmitate or oleate per mol of protein. These preparations correspond to serum free fatty acids (FFA) concentrations of 4000, 2000 and l30 µEq/l. By the dialysis-equilibrium technique, the capacity of these albumin preparations to bind some or all of these ligands was measured: Salicylate, octanoate, bromsulfophthalein (BSP), phenylbutasone, sulfadiasine, thiopental, bishydroxycoumarin and diphenyihydantoin. Analysis of SCatchard plots shows that Salicylate, octanoate, BSP and phenylbutazone occupied three classes of binding site in BSA, whereas for sulfadiasine, bisbydroxycoumarin, thiopental and diphenylhydantoin only one type of binding site was detected. The binding of all eight ligands to BSA was inhibited by palmitate at a molar ratio of 7. The inhibition affected either the number of binding sites in a particular class available to the ligand, or the association constant for the interaction of the site with the ligand or both. Binding to salicylate, octanoate, sulfadiasine, thiopental and diphenylhydantoin was markedly reduced, with 50% or more reduction in number of clasa 1 sites available, whereas binding of BSP, phenylbutasone and bishydroxycoumarin was less inhibited, the number of available class 1 sites being preserved. The inhibitory effect of oleate at a molar ratio of 7 on the binding properties of BSA for salicylate, octanoate and diphenylhydantoin was closely similar to that of 7 mol of palmitate. Palmitate at a molar ratio of 3.5 inhibited the binding of salicylate and octanoate to BSA, but the effect was only a small fraction of that observed with 7 mol of palmitate; 3.5 mol of plamitate did not inhibit binding of diphenylhydantoin. The binding of salicylate, octanoate and diphenylhydantoin to HSA containing 7, 3.5 or l0.05 mol of FFA was qualitatively similar to that observed with the corresponding series of BSA preparations. The binding of salicylate, octanoate and diphenylhydantoin by rabbit sera with FFA concentrations ranging between 300 and 3000 and 3000 µEq/l was also measured; these sara were obtained by injecting the animals with graded doses of the lipolytic hormone adrenocorticotropin. Below the concentration 1700 µEq/l, FFA did not inhibit binding capacity of the serum detestably. concentrations above 2200 µEq/l were consistently associated with a 20 to 26% reduction in the binding of all three ligands. These experiments suggest that serum FFA in the concentration range of 2000 to 4000 µEq/l have a general inhibitory effect on the capacity of serum albumin to bind many ligands of widely different structure, but that at concentrations below 2000 µEq/l this effect is minor or absent.

Production of Albumin and Other Serum Proteins by Clonal Cultures of Normal Human Liver

Abstract: Clonal cell strains have been isolated from normal human liver. These cells, while resembling fibroblasts morphologically, function as hepatocytes, as shown by their ability to synthesize and secrete an antigen identical to human serum albumin. Human diploid and aneuploid cell lines from nonliver sources do not exhibit this property. The spectrum of serum proteins synthesized varied from clone to clone and cell line to cell line.

Optical studies of drug-protein complexes. V. The interaction of phenylbutazone, flufenamic acid, and dicoumarol with acetylsalicylic acid-treated human serum albumin.

Abstract: When acetylsalicylic acid is incubated at 37° with human serum albumin the protein is acetylated by the drug. Acetylation of human serum albumin by acetylsalicylic acid does not appear to cause any conformational changes, since the intrinsic optical activity of the protein is unaltered. However, the positive extrinsic Cotton effect generated at 287 mµ by the binding of phenylbutazone to human serum albumin increased in amplitude after the protein had been acetylated by acetylsalicylic acid. In contrast, the strong positive extrinsic circular dichroic band which appears at 296 mµ when flufenamic acid binds to human serum albumin decreased in amplitude when the protein was acetylated by acetylsalicylic acid, while the weaker negative band at 345 mµ was unchanged. Acetylsalicylic acid treatment of human serum albumin did not affect the strong negative extrinsic circular dichroic band at 305 mµ generated by the binding of dicoumarol. These results suggest that acetylation of human serum albumin by acetylsalicylic acid specifically modifies the binding sites for phenylbutazone and flufenamic acid. No change in the extrinsic optical activity of bound phenylbutazone or flufenamic acid was observed when acetylsalicylic acid was replaced by salicylic acid or by other acylating agents such as benzylpenicillin, benzylpenicillenic acid, and acetic anhydride. Equilibrium dialysis measurements showed that acetylation by acetylsalicylic acid also increased the affinity of human serum albumin for phenylbutazone but decreased its affinity for flufenamic acid. The affinity of the acetylsalicylic acid-treated human serum albumin for dicoumarol was the same as that of albumin incubated alone. Thus the plasma binding of phenylbutazone or flufenamic acid in a patient may be altered by the prior ingestion of acetylsalicylic acid.

Macrophage-antigen interaction: uptake, metabolism and immunogenicity of foreign albumin.

Abstract: The uptake of radioiodinated mouse and human serum albumin (HSA) by macrophages from non-immunized CBA mice depended on the degree of aggregation of the albumin, and not on cytophilic antibody on the surface of the cell. Autologous and heterologous albumin of comparable physical states were taken up and metabolized equally by macrophages. The HSA taken up by macrophages was rapidly catabolized, except for a small amount that remained associated with the cell both intracellularly and on the surface for long periods in culture. The membrane-bound albumin represented non-pinocytosed molecules. This membrane-bound antigen was maintained independently of intracellular material and was responsible for most of the immunogenicity of macrophage-bound albumin. A portion of albumin taken up by macrophages was released undegraded into the supernatant during culture. The metabolism of HSA was directly proportional to the degree of aggregation of the albumin as increased aggregation resulted in more extensive catabolism.

Fluorescent modification of serum albumin by lipid peroxidation

Abstract: Peroxidation of fatty acids bound to human serum albumin results in the production of fluorescent chromophores in the protein when it is stored in the liquid, powdered or crystalline state. Peroxidizing polyunsaturated fatty acid esters, and carbonyls derived from peroxidizing lipids react with amino groups of protein to give products that have fluorescence spectra very similar to those observed for stored commercial preparations of serum albumin.

The Chemotactic Activity of Native and Denatured Serum Albumin

Abstract: Native human serum albumin (HSA) is not chemotactic for neutrophil leucocytes. Certain treatments such as acidification or reduction-alkylation may cause HSA preparations to become moderately chemotac

Specificity of Helper Function

Abstract: Publisher Summary This chapter presents a study analyzing specificity of helper function. Bovine serum albumin (BSA, “reinst”) was obtained from Behringwerke. Sheep serum albumin (SSA, Pentex) was further purified by passage over Sephadex G-200 (Pharmacia) and chromatography on DEAE-Sephadex A-50 (Pharmacia) using a linear gradient from 0.02 M potassium phosphate buffer pH 7.3, to 0.5 M sodium chloride in the same buffer. Human serum albumin (HSA) was a product of Serva, Heidelberg. 4-Hydroxy-5-iodo-3-nitrophenacetyl (NIP) azide was prepared and coupled to protein. The hapten–protein conjugates were freed of low molecular weight reaction products by passing the reaction mixture over Sephadex G-50. The number of NIP groups per protein molecule was determined spectrophotometrically. The results of this study suggested that the majority, if not all, antibodies in both anti-BSA and anti-SSA antisera cross react with the heterologous antigen and that the cross reaction between SSA and BSA is nonreciprocal. Anti-BSA antibodies react much better with SSA than anti-SSA antibodies with BSA.

The binding of human serum albumin by monodisperse polystyrene latex particles.

Abstract: The binding of human serum albumin by monodisperse latex particles was studied applying the radioisotope labelling technique. The radiochemically active substance was 131I-labelled albumin and the latices were monodisperse samples ranging in particle size from 200 to 940 nm. All experiments were performed in buffered solutions at pH 8.0 and the ionic strength 0.05. In one type of binding experiments human serum albumin was added in great excess leading to a saturation of latex particle surface. The excess albumin was removed by centrifugation and washing of the sediments by pure buffer. For two latex samples the bindng isotherms were determined. The results of the experiments with excess albumin suggest that a nearly constant amount is bound per unit paricle surface irrespective of the latex sample and particle size. One washing was shown to take away approximately some 10% of bound albumin from the particle surface demostrating fairly strong binding. From the binding isotherms the binding constants K and the standard free energies of binding ΔGo were estimated. Values of K about 6μM−1 and ΔGo about –9 kcal/mol indicate high affinity of human serum albumin to the latex particle surface. The results of the present experiments are discussed from the point of view of recent findings on protein interactions with detergent molecules. The results indicate a possible expansion of the tertiary structure of the human serum albumin molecule in its part attached to the particle surface whereas the part of the molecule oriented to the solution remains in its native conformation as is seen from the preserved immunochemical activity against specific antibodies.

Quenching of the emission of tryptophan, tyrosine, and serum albumins by cupric ion

Abstract: The effect of cupric ion on the emission of tryptophan, tyrosine, and serum albumins is studied by emission spectroscopy and lifetime measurements. It is found that whenever cupric ion is bound to tryptophan or tyrosine, their emissions are quenched completely. The quenching may be due to an electron transfer mechanism. The fluorescence of complexes of cupric ions with serum albumins is partially quenched; this is because energy is transferred from tryptophan to the complexed cupric ions by a dipolar energy transfer mechanism. It is deduced from the present study that the tryptophan in the human serum albumin molecule is between 11 and 16 A from the nearest eupric ion binding sites (assumed to be at the surface of the protein) and that one of the tryptophan in the bovine serum albumin molecule is very close to the cupric ion binding sites and the other is near the center of the bovine serum albumin molecule. It is also found that the deuterium solvent effect on serum albumin fluorescence is very small, and that the quenching of bovine serum albumin fluorescence at the N-F transition is the result of quenching of the fluorescence of both tryptophans. The phosphorescence lifetime apparatus, capable of measuring decay times of signals with intensities changing over a few orders of magnitude, and the ratio spectrofluorometer, both of which were constructed in this laboratory, are also described.

Acidic monosaccharide-substituted proteins

Abstract: 1. AN ACIDIC MONOSCCHARIDE-SUBSITUTED PROTEIN SELECTED FROM THE GROUP CONSISTING OF N-ACETYLNEURAMINYL INSULIN (BOVINE), N-ACETYLNEURAMINYL INSULIN (PIRCINE), N-ACETYLNEURAMINYL HUMAN SERUM ALBUMIN, N-ACETYLNEURAMINYL BOVINE SERUM ALBUMIN, N-ACETYLNEURAMINYL HUMAN GROWTH HOMONE, GLUCONYL INSULIN (BOVINE), GLUCONYL INSULIN (PORICE), GLUCONYL HUMAN SERUM ALBUMIN, AND GLUCONYL HUMAN GROWTH HORMONE WHEREIN THE SUBSTITUTION OCCURS AT AN AVALIBLE A-AMINO OR $AMINO GROUP.

Unusual Albumin Variants in Indonesians and Malayan Aborigines

Abstract: Two unusual electrophoretic variants of serum albumin occurring along with normal albumin were found in Asians. One (albumin Gombak), a slowly migrating variant discovered in 2 Malayan aborigine sisters, was not distinguishable from a rare variant previously reported in a French family. The other (albumin Medan), a rapidly migrating variant found in an Indonesian family in Northern Sumatra, is distinguishable from 4 other rapidly migrating variants. At least 18 different electrophoretically detectable variants of human serum albumin have now been reported.

An enhancing effect of albumin on the determination of cold hemagglutinins.

Abstract: . Serum from a patient with hypogammaglobulinemia was found to have a cold agglutinin titer of 128 when diluted in saline and 131,000 when diluted in 22% bovine serum albumin. Human Serum albumin and a non-protein-containing commercial agglutination potentiator had similar enhancing properties. A degree of albumin enhancement of cold agglutination was observed in approximately 25% of normal and patient sera examined. The mechanism of enhancement and the possible clinical significance of the phenomenon are not yet known.

Interaction Between 5-Dimethylaminonaphthalene-1-Sulfonamide and Human Serum Albumin

Abstract: The fluorescence of DNSA (5-dimethyl-aminonaphthalene-1-sulfonamide) in solution with human serum albumin has been used to study the binding characteristics of DNSA to this protein. Such binding is apparently hydrophobic in nature and occurs near the tryptophan residue of the protein. Various drugs displaced DNSA from human albumin in direct proportion to their own affinities for plasma protein. An association constant of 3.68 × 104 1/m was approximated for the binding of DNSA to human albumin.

Competition between Drugs and Normal Substrates for Plasma and Tissue Binding Sites

Abstract: Many drugs are extensively but reversibly bound to plasma proteins (Meyer and Guttman, 1968). Albumin is particularly important in this regard since it binds a variety of substances of diverse structure and activity. In addition to drugs, various naturally occurring compounds such as bilirubin, thyroxine, fatty acids and certain steroids bind to albumin. The number of binding sites on albumin which have a relatively high affinity for drugs and hormones is limited and, under certain conditions, compounds may compete for such sites (Brodie, 1965). The rate of metabolism and excretion as well as the magnitude of the pharmacologic response is dependent, in part, upon the concentration of unbound drug. Thus, marked changes in pharmacologic activity and even toxicity may be observed when one compound is displaced by another from albumin (Brodie, 1966; Solomon, 1968). Such is particularly the case when the displaced compound is metabolized and/or excreted slowly. This review is concerned with the interaction between drugs and certain naturally occurring compounds relative to binding on plasma proteins.