Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.4.21.7 (plasmin)
 9,023 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Fibrinogen (approximately 10(-5) M) labilizes heterologous interactions within the thrombin-modified factor XIII zymogen (i.e., XIII' = a2'b2) so that, in the time frame (ca. 10 min) of normal clotting in plasma (37 degrees C, mu = 0.15, pH 7.5), 1.5 mM Ca2+ is sufficient to cause the release of the noncatalytic b subunits and also the unmasking of 1 equiv of iodo[1-14C]acetamide-titratable group per catalytic a subunit. Under similar conditions, but in the absence of fibrinogen, approximately 10 mM Ca2+ would be needed to achieve the same effect. Thus, by promoting the conversion of XIII' to XIIIa (i.e., a2'b2 leads to a2* + b2), fibrinogen functions as a physiologically important Ca2+-modulator protein. Total plasmin digests of fibrinogen display the regulatory phenomenon nearly as well as the parent protein. In an attempt to identify the structural domain on the fibrinogen which is responsible for this novel function of the molecule, it was found that two overlapping fragments derived from the midsections of the alpha chains, either by CNBr cleavage (residues 243-476) or by plasmin digestion (residues 242-424), are active.
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PMID:Alpha-chain domain of fibrinogen controls generation of fibrinoligase (coagulation factor XIIIa). Calcium ion regulatory aspects. 611 70

The M(r) = 94,000 heavy chain of bovine factor Va contains 10 cysteine residues which are distributed in the 2 A domains which make up this portion of the factor V molecule. The A1 domain contains four cysteines while the A2 domain contains six cysteines. The locations of disulfide bridges and free cysteines in bovine factor Va heavy chain were analyzed using iodo[14C]acetamide-labeled factor Va heavy chain digested with trypsin, plasmin, V-8 protease, and cyanogen bromide. Following HPLC separation of the resulting peptides, free cysteines were identified by the incorporation of radioactivity while disulfide-containing peptides were detected using an SBD-F fluorometric assay after reduction. All cysteine-containing peptides were analyzed by amino acid sequence analysis. The four cysteines in the A1 domain are associated with two disulfide bonds, Cys139-Cys165 and Cys220-Cys301. One disulfide bond was explicitly identified in the A2 domain; Cys471-Cys497, and a free cysteine was found in the A2 domain at Cys538. Significant difficulties were encountered in preparing identifiable or soluble peptides which would permit the explicit identification of the three remaining cysteines in the A2 domain. On the basis of homology, it is likely that Cys589 is a free SH while a disulfide bridge exists between Cys579 and Cys660. Thus, three major disulfide bonding patterns, characterized as "alpha", "beta", and "gamma" loops, are found in factor V. Each A domain contains a 26 residue "alpha loop at positions 139-165, 471-497, and 1684-1710. The A1 and A2 domains each contain 81 amino acid residue "beta" loops at 220-301 and 579-660.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Determination of the disulfide bridges in factor Va heavy chain. 794 16