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)

Bovine growth hormone (bGH) was submitted to iodination using limited amounts of oxidizing reagent, yielding a derivative with no more than 1-g-atom of iodine per mole of hormone. Analysis of the hydrolysis products indicated that monoiodotyrosine was almost the only product of substitution. Isolation and identification of the tryptic fragments showed that half of the 125I-labeled bGH molecules were iodinated in Tyr 174, followed by Tyr 158 (16%) and Tyr 42 (14%). Frontal gel chromatography indicated that the preparation did not contain significant amounts of unreacted bGH. Circular dichroism evidenced structural similarity between the native and the iodinated bGH. The iodinated hormone, like the native protein, undergoes self-association. The dissociation constant of the iodo-labeled bGH self-association equilibrium showed a two-fold increase when compared to that corresponding to the unlabeled hormone. At pH 8.5, where the equilibrium constant was estimated, one tenth of the molecules bear a charged iodotyrosyl residue (average pKapp = 9.3), which could account for part, if not all, of the observed difference regarding self-association. By this criterion, the presence of the iodine atom does not disturb the area engaged in dimer formation.
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PMID:Structural characterization of iodinated bovine growth hormone. 711 92

Berberine chloride (BC) is a major active constituent of coptis and can be used as an antipyrotic and antibacterial medicine. Frontal analysis was used to investigate the changes in the binding constant (K), retention factor (k), binding ratio (PPB) and mole of binding sites (m(L)) for the binding of BC on an immobilized bovine serum albumin (BSA) column at several temperatures and to obtain the thermodynamic parameters in the binding process. At 30 degrees C, the binding constant was 4.79 x 10(4) L/mol. K, k and m(L) all decreased as the temperature was increased. Among these three parameters, the change magnitude in m(L) was the most significant. It could be concluded that the decrease in the retention of BC was caused by the decrease of both K and m(L), and the change in the configuration of BSA was considered to be the main reason for the decrease of binding site. The thermodynamic analysis indicated that the main driving force for the interaction between BC and BSA is electrostatic force.
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PMID:[Investigation on binding interaction of berberine chloride with bovine serum albumin immobilized onto chromatographic supports by frontal chromatography]. 1767 27

Protein native state aggregation, a major problem in pharmaceutical and biological processes, has been addressed pharmacologically by the addition of protein-binding excipients. Heparin (Hp), a highly sulfated polysaccharide, interacts with numerous proteins with moderate to high affinity, but reports about its effect on protein aggregation are contradictory. We studied the pH dependence of the aggregation of antithrombin (AT) and bovine serum albumin (BSA) in the presence and absence of heparin. High-precision turbidimetry showed strong aggregation for both AT and BSA in I = 10 mM NaCl, conditions at which electrostatically driven Hp binding and aggregation both occur, with more obvious aggregation of heparin-free AT appearing as larger aggregate size. Aggregation of AT was dramatically inhibited at Hp: protein 6:1 (mole ratio); however, the effect at 0.5:1 Hp:protein was greater for BSA. Frontal analysis capillary electrophoresis showed a much larger equilibrium association constant Kobs between Hp and AT, in accord with the onset of Hp binding at a higher pH; both effects are explained by the higher charge density of the positive domain for AT as revealed by modeling with DelPhi. The corresponding modeling images showed that these domains persist at high salt only for AT, consistent with the 160-fold drop in Kobs at 100 mM salt for BSA-Hp binding. The smaller inhibition effect for AT arises from the tendency of its uncomplexed monomer to form larger aggregates more rapidly, but the stronger binding of Hp to AT does not facilitate Hp-induced aggregate dissolution which occurs more readily for BSA. This can be attributed to the higher density of AT aggregates evidenced by higher fractal dimensions. Differences between inhibition and reversal by Hp arise because the former may depend on the stage at which Hp enters the aggregation process and the latter on aggregate size and morphology.
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PMID:Inhibition of antithrombin and bovine serum albumin native state aggregation by heparin. 2431 40