Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.4.21.1 (chymotrypsin)
 10,938 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The amino-acid sequence of the heavy chain of bovine blood coagulation factor X1 (Stuart factor) isolated before and after activation has been determined. Sequence analysis was performed on fragments obtained by cleavage with cyanogen bromide and by tryptic digestion. Comparison of the complete sequence with those of other hepatic and pancreatic serine proteases demonstrates homology of the heavy chain of activated factor X1 (factor X1a) with the B chain of bovine thrombin as well as with bovine trypsin, chymotrypsins A and B, and porcine elastase. The activation peptide cleaved near the amino terminus by a protease from Russell's viper venom differs in both size and sequence from those of other serine proteases. With three exceptions, all of the residues which are important in the catalytic functions of trypsin and chymotrypsin occur in corresponding loci in the heavy chain of factor Xa. These finding suggest that the three-dimensional structure of the heavy chain is similar to that of the pancreatic serine proteases and that these enzymes have evolved from a common ancestral gene.
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PMID:Bovine factor X1 (Stuart factor): amino-acid sequence of heavey chain. 105 93

Limited proteolysis of bovine blood coagulation Factor X by chymotrypsin produces a derivative in which the light chain is cleaved between Tyr 44 and Lys 45. Two peptide products, residues 1-44 of the Factor X light chain and a modified zymogen, Factor X(-GD) have been isolated and characterized by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, elution behavior on anion-exchange chromatography, amino acid composition, and by partial amino acid sequence determination. Factor X(-GD) no longer contains the 12 gamma-carboxyglutamic acid residues of the native zymogen and thus serves as a model for investigation of the properties conferred on Factor X by the presence of gamma-carboxyglutamic acid. Cleavage of Factor X at Tyr 44 by chymotrypsin is inhibited by Ca2+ and Mg2+ ions. Factor X(-GD) is activated by the coagulation factor activator of Vipera russellii venom, but at less than 1% of the rate of activation of native Factor X. The susceptibility of Tyr 44 to chymotryptic cleavage implies that this residue is on the surface of the light chain of Factor X. Factor Xa(-GD) is indistinguishable from native Factor Xa in its activity on Benzoyl-Ile-Glu-Gly-Arg-p-nitroanilide, on prothrombin alone, and on prothrombin plus Factor Va. In the presence of phospholipid the rate of prothrombin activation catalyzed by Factor Xa(-GD) is the same as in the absence of phospholipid.
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PMID:Preparation and properties of derivatives of bovine factor X and factor Xa from which the gamma-carboxyglutamic acid containing domain has been removed. 351 64

In this report, we describe the anticoagulant and antithrombotic properties of a peptide (residues 1-44) derived from the amino-terminus of the bovine Factor X light chain by limited proteolysis with chymotrypsin, and subsequently purified by QAE-Sephadex chromatography. The effect of Factor X gla-peptide on the activation of human 3H-Factors IX and X was studied using radiometric assays and purified coagulation factors. Factor VIIa-tissue factor catalyzed activation of Factors IX and X was half-maximally inhibited by Factor X gla-peptide at concentrations of 0.8 microM and 0.2 microM, respectively. Factor IXa-VIII catalyzed Factor X activation was half-maximally inhibited at a gla-peptide concentration of 0.5 microM. In addition, thrombin formation by platelets incubated with Factor Xa and prothrombin could be similarly blocked by gla-peptide. Studies with bovine aortic endothelial cells indicated that the Factor X gla-peptide blocked in parallel Factor X binding and activation on the cell surface. Decarboxylation of the peptide by acid heat treatment destroyed its anticoagulant activity. The in vivo anticoagulant potential of native gla-peptide was demonstrated by a rapid prolongation of the PT and APTT following intravenous infusion into a rabbit. In addition, gla-peptide prevented thrombus formation in response to Factors IXa and Xa, but not thrombin, in a Wessler venous stasis model.
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PMID:Anticoagulant and antithrombotic properties of a gamma-carboxyglutamic acid-rich peptide derived from the light chain of blood coagulation factor X. 381 May 64

Activation of bovine plasma prekallikrein was investigated with several proteinases. Highly purified bovine plasma prekallikrein was rapidly activated to kallikrein [EC 3.4.21.8] by bovine activated Hageman factor, trypsin [EC 3.4.21.4] and Pronase P (proteinases from Streptomyces griseus) and more gradually by papain [EC 3.4.22.2] and ficin [EC 3.4.22.3]. Activation of prekallikrein was also observed with bovine plasmin [EC 3.4.21.7], but not with bovine clotting factors Xa (Stuart factor) [EC 3.4.21.6] and IXa (Christmas factor) or thrombin [EC 3.4.21.5]. Urokinase [EC 3.4.99.26], Reptilase, collagenase [EC 3.4.24.3], elastase [EC 3.4.21.11], alpha-chymotrypsin [EC 3.4.21.1], Nagarse [EC 3.4.21.14], and stem bromelain [EC 3.4.22 4] did not convert prekallikrein to kallikrein. Plasma kallikrein activated to Hageman factor released kinin rapidly from bovine high molecular weight (HMW) kininogen. However, from bovine low molecular weight (LMW) kininogen, liberation of kinin was extremely slow. The kallikrein activity was inhibited by soybean trypsin inhibitor (SBTI), Trasylol, diisopropylfluorophosphate (DFP), and N-alpha-tosyl-L-lysine chloromethylketone (TLCK), but not by egg-white trypsin inhibitor (EWTI), lima bean trypsin inhibitor (LBTI), heparin or hexadimethrine bromide (Polybrene). The kallikrein formed an enzyme-inhibitor complex with SBTI and Trasylol, but not with LBTI. Prekallikrein did not react with SBTI. Prekallikrein consists of a single polypeptide chain of molecular weight about 90,000, as estimated by sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis. Activation of prekallikrein by Hageman factor was found to involve cleavage of the single peptide bond on the disulfide-bridged polypeptide chain, and no change of molecular weight was observed during the activation. The peptide bond cleaved in prekallikrein by the activation was an Arg-X peptide bond on a disulfide-bridged polypeptide chain.
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PMID:Studies on prekallikrein of bovine plasma. II. Activation of prekallikrein with proteinases and properties of kallikrein activated by bovine Hageman factor. 676 24

To identify sequences in prothrombin (fII) involved in prothrombinase complex (fXa.fVa.fII.phospholipids) assembly, synthetic peptides based on fII sequences were prepared and screened for their ability to inhibit factor Xa (fXa)-induced clotting of normal plasma. The fII peptide (PT473-487, homologous to chymotrypsin residues 149D-163) potently inhibited plasma clotting assays and prothrombinase activity, with 50% inhibition of 12 and 10 microm peptide, respectively. Prothrombinase inhibition by PT473-487 was factor Va (fVa)-dependent and sequence-specific, because the peptide did not inhibit fII activation in the absence of fVa, and a scrambled sequence peptide, PT473-487SCR, was not inhibitory. Peptide PT473-487 did not inhibit the amidolytic activities of fXa and thrombin, suggesting that the peptide did not alter the integrity of their active sites. To determine whether PT473-487 interacted directly with fVa, fluorescein-labeled fVa (Fl-fVa) was prepared. When PT473-487 was titrated into samples containing phospholipid-bound Fl-fVa, the peptide increased fluorescein anisotropy (EC(50) at 3 microm peptide), whereas the control peptide PT473-487SCR did not alter the anisotropy, suggesting a direct binding interaction between PT473-487 and Fl-fVa. These functional and spectroscopic data suggest that fII residues 473-487 provide fVa-binding sites and mediate interactions between fVa and fII in the prothrombinase complex.
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PMID:Prothrombin residues 473-487 contribute to factor Va binding in the prothrombinase complex. 1533 2