Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0027960 (mole)
 21,279 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Human immunoglobulin G, human serum albumin and testosterone were labelled with the 4-aminosalicylic acid derivative of diethylenetriaminepentaacetic acid complexed with terbium ions. An exceptionally large amount of label, of the order of a few hundred moles of complex per mole of analyte, could be conjugated to the compounds tested by the use of poly-L-lysine. Self-quenching appears to be minimal, even with this high local concentration of fluorophores. The tracers were stable at 4 degrees C, and gave competitive calibration graphs at physiological concentrations.
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PMID:Multiple labelling of immunoglobulin G, albumin and testosterone with a fluorescent terbium chelate for fluorescence immunoassays. 259 1

Reactivity of tubulin SH groups, estimated by the slope to the curve in the SH-SS exchange reaction with 5-5' dithiobis (2-nitrobenzoic acid), was compared with that of bovine serum albumin (BSA) and studied in presence of various ligands. A small part of tubulin SH groups (12%) showed a higher reactivity, while the remaining portion had a smaller reactivity than that of BSA. The SH group reactivity of tubulin but not the total amount (12.8 mu/mole) diminished when assayed with colchicine and MgCl2 (0.1 and 0.2 mM, respectively); 0.2 mM CaCl2 increased the reactivity at the maximum level. On the basis of the biological role of tubulin SH groups and of the opposite effects exerted by Ca++ and Mg++ on the protein, the results presented here seem to indicate a correlation between conformational states of tubulin and its biological functions.
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PMID:The SH-SS exchange reaction between the Ellman's reagent and protein containing SH groups as a method for determining conformational states: tubulin. 274 39

The interaction of native and modified bovine serum albumin (BSA) with catechin, a flavanoid having vitamin P activity, has been studied using equilibrium dialysis, pH-metric, viscosity and spectrophotometric methods. The order of reactivity of catechin binding to proteins was found to be: esterified BSA greater than BSA greater than formylated BSA greater than acetylated BSA with log K values of 3.778, 3.879, 3.748 and 3.813 and free energy change equal to -5.11, -5.16, -5.07 and -5.15 kcal/mole, respectively.
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PMID:Study of interaction between catechin and native and modified bovine serum albumin by physico-chemical methods. 277 9

Phospholipase A2 (PLA2) inhibits ligand binding to sarcolemmal muscarinic receptors in heart. To determine whether this effect of PLA2 is mediated by membrane accumulation of non-esterified fatty acids (FFA), the effect of selected fatty acids on the binding of 3H-quinuclidinyl benzylate (3H-QNB) to purified canine sarcolemmal membranes before and after PLA2 treatment was examined. Equilibrium 3H-QNB binding was inhibited by 5 min exposure of membrane vesicles to oleic, linoleic or arachidonic acid (IC50 = 6.3 +/- 0.9, 9.9 +/- 1.1, and 6.8 +/- 0.4 microM, respectively); the saturated fatty acids, stearic and palmitic acid (10 microM) had no effect. Scatchard analysis of equilibrium binding isotherms showed that the effect of the unsaturated fatty acids to inhibit 3H-QNB binding reflected a decrease of Bmax and a reduction of the affinity of the remaining receptors. The effect of unsaturated fatty acids was dependent on the mole ratio of fatty acid to membrane phospholipid present (FFA/PL ratio). Washing of fatty acid-treated membranes with bovine serum albumin (BSA) resulted in partial recovery of both maximal binding (Bmax) and affinity. The fatty acid-induced reduction of Bmax was also attenuated if binding was started by simultaneous addition of 3H-QNB and FFA. Similarity of the FFA induced effects on 3H-QNB binding to sarcolemmal muscarinic receptors to those induced by PLA2 suggest that membrane accumulation of unsaturated fatty acids underlies in part the effect of PLA2. Furthermore, modification of the receptor-ligand interaction by changes in the membrane lipid composition may be prevented by ligand occupation of the receptor.
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PMID:Inhibition of 3H-quinuclidinyl benzylate binding to cardiac muscarinic receptor by long chain fatty acids can be attenuated by ligand occupation of the receptor. 277 5

Modified polyvinylimidazole-coated silica materials containing disulphide groups were evaluated for the covalent chromatographic purification of bovine serum albumin. They are inert toward this protein and allow the isolation of 40 mg of mercaptalbumin (0.97-1.05 SH per mole) in less than 3 h. They are easily regenerated.
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PMID:Rapid preparation of bovine mercaptalbumin by means of covalent chromatography on silica-based materials. 282 93

Numerical analysis of multiple binding of two ligands to one carrier has been accomplished, using the principle of several sets of acceptable binding constants, with bilirubin-laurate-albumin as an example. Binding of bilirubin to defatted human serum albumin was investigated by a spectroscopic method, based upon a difference of light absorption spectrum for free and bound bilirubin. The observations were supplemented with previous data from an independent technique, measurement of oxidation rates of free bilirubin with hydrogen peroxide and peroxidase. A continuous isotherm was obtained, showing binding of at least 4 mol bilirubin per mole albumin with the following stoichiometric binding constants, 1.11 X 10(8), 1.7 X 10(7), 8 X 10(5), and 4 X 10(4) M-1 at pH 8.2, ionic strength 0.15 M, 25 degrees C. The binding is anticooperative at all steps. A saturation level was not reached. Cobinding of bilirubin and laurate was studied, with up to 2 mol of each ligand per mole albumin, using the peroxidase method for determination of free equilibrium concentrations of bilirubin, and a dialysis rate technique for free laurate. The findings could be described in terms of a stoichiometric model. Heterotropic cooperativity was present among the first bilirubin and the first and second laurate molecules. More than two molecules of either ligand can be bound at the same time.
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PMID:Multiple binding of bilirubin to human serum albumin and cobinding with laurate. 282 43

This study aimed at increasing the efficiency and shortening the time required for administering cerebroside sulfate to cultured cells. For this purpose several modes of dispersion of a fluorescent derivative of cerebroside sulfate (sulfatide), in which the natural fatty acid has been replaced by pyrenedodecanoic acid (P12), were incubated with the cells. This fluorescent derivative of cerebroside sulfate (P12-CS) was introduced into the growth medium of the cells using the three following modes of dispersion: (1) P12-CS was dissolved in dimethylsulfoxide and added to the medium, (2) it was precomplexed with serum albumin or (3) incorporated into small, unilamellar vesicles (SUV) of phosphatidylcholine. With each of these respective modes of dispersion, the P12-CS was incubated for periods up to 48 h with cultured lymphoblasts or fibroblasts. Uptake by the cells could be determined by recording directly the cell-associated fluorescence, using a suspension of washed intact cells. The cell lipids were subsequently extracted with mixtures of chloroform/methanol and their fluorescence recorded. When related to the incubation time, uptake of P12-CS by the cells increased continuously using each of the above dispersions. The appearance of fluorescence at 475 nm ('excimer') and the ratio of this to the monomolecular fluorescence at 378 nm ('E/M') could be used as a measure for the presence of the internalized P12-CS in aggregated or fully dispersed states. These values (i.e., E/M), recorded on the suspensions of intact cells were rather high using the aqueous dispersions, intermediate values were observed using the SUV and rather low E/M values (0.5 or less) were observed using the preformed albumin-(P12-CS) complexes. Increasing the mole ratio of albumin to P12-CS (i.e., from 1:2 to 2:1 m/m), decreased the quantity of sulfatide which was taken up by the cells but also further decreased the E/M ratio, suggesting a fully dispersed state of the pyrene lipid within the cell. This indicated that, using an optimal albumin to P12-CS ratio of 1-2 (or its equivalent values in fetal calf serum) permitted an influx of single molecules of P12-CS into the cells. After 48 h, about 50% of the fluorescence of skin fibroblasts was found in metabolic degradation products of P12-CS. The parallel value for fibroblasts derived from a patient with metachromatic leukodystrophy was only about 5%. Appearance of the excimeric emission of a dispersion of P12-CS in water permitted estimation of its critical micellar concentration as being 7.5 x 10(-7) M.
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PMID:Correlation of the dispersion state of pyrene cerebroside sulfate and its uptake and degradation by cultured cells. 292 62

The fluorescence properties of fluorescein bound to protein are used to quantitate by flow cytofluorometry the degradation of fluorescein-labeled alpha-glucosylated serum albumin (fluorescein-labeled neoglycoprotein) after endocytosis by the membrane lectin of Lewis lung carcinoma cells (3LL cells). The quantum yield of fluorescein bound to a protein decreases when the number of fluorescein residues per protein molecule increases; however, after proteolytic digestion the mean fluorescence intensity of a fluorescein molecule is constant and equal to that of free fluorescein. The extent of the degradation of the endocytosed neoglycoprotein was determined with a flow cytofluorometer by using two neoglycoproteins containing either a small or a large number of fluorescein residues per neoglycoprotein molecule. At 4 degrees C, 3LL cells bind 750,000 molecules of fluorescein-labeled alpha-glucosylated serum albumin with an apparent binding constant of 2 X 10(6) 1 X mole-1. At 37 degrees C, after 4 hr incubation 2.2 X 10(6) molecules of fluorescent alpha-glucosylated serum albumin were cell-associated, and of these at least one third were degraded.
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PMID:Estimation of the degradation of endocytosed material by flow cytofluorometry using two neoglycoproteins containing different numbers of fluorescein molecules. 295 7

Marked alterations in feeding and defense behaviour and motor activity partly resembling the effects of exogenous beta-endorphin administration were demonstrated in the experiments on rats. These alterations were observed after immunization with beta-endorphin--bovine serum albumin conjugate (two subcutaneous injections at a 7-day interval at a dose of 75 micrograms, 1 mole BSA/6 moles beta-endorphin mixed with complete Freund's adjuvant). A decrease in beta-endorphin content in some brain structures was noted. Unlike control animals, the immunized rats revealed within 3-4 weeks an increase in food intake without any rise in body weight and practically no response to handling.
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PMID:[Forms of goal-directed behavior as affected by induced changes in the level of endogenous beta-endorphin in rats]. 296 Mar 90

Diisocyanates are highly reactive industrial chemicals that have been shown to possess toxic activity, including potential for allergic sensitization. To assist in diagnosis of sensitization, immunoassays for diisocyanate-specific antibodies are performed; such assays require preparation of diisocyanate-containing hapten-protein conjugates. Conditions were investigated for formation of conjugates yielding varying degrees of hapten binding. Relative concentrations of haptens and proteins were varied as were pH, temperature, and time of reaction. Quantitation of 4,4'-diisocyanatodiphenylmethane (MDI) binding with human serum albumin (HSA) was assessed by absorbance of the isolated conjugates at 250 nm after determination of the molar extinction coefficient for MDI. At pH 7.4 and 37 degrees C, the binding reaction was found to be biphasic with binding of 5-6 mol of MDI groups/mol of HSA within the first minute, followed by incorporation at a rate of 0.16 mol/min during the next 2 h. Evaluation of reaction products using SDS-PAGE revealed extensive inter- and intramolecular cross-linking of HSA by MDI. Intramolecular cross-linking was accompanied by an increased migration of conjugates from an initial molecular mass of 66 kDa, typical of HSA, to a molecular mass of 44 kDa. The change in migration was also produced by using disuccinimidyl tartarate (DST) as hapten and was eliminated when DST was cleaved with sodium periodate. It was attributed to altered protein shape. Conditions that favored binding of MDI with HSA were a high relative concentration of MDI:HSA, a pH of 9.4, and a temperature of 37 degrees C. Under such conditions it was calculated that 53 mol of MDI were bound per mole of HSA after 24 h.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Intra- and intermolecular reactions of 4,4'-diisocyanatodiphenylmethane with human serum albumin. 297 44


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