Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: 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 effects of specific low- and high-molecular weight inhibitors of chymase and tryptase and F(ab')2 of antichymase on histamine release from activated mast cells were examined. The release of histamine induced by anti-rat immunoglobulin E was markedly inhibited by F(ab')2 fragments of antichymase and the low-molecular weight inhibitor of chymase chymostatin, whereas release of histamine induced by calcium ionophore A23187 was inhibited only by chymostatin. Neither the inhibitor nor the antibody affected histamine release induced by compound 48/80. These results suggest that two main chymotrypsin-type proteases are involved in process of degranulation: one is chymase, which acts at a step before calcium entry, and the other is an unidentified protease, which acts at a step after calcium entry. These results are summarized in Figure 8. After degranulation, released chymase remains associated with the cell surface while released tryptase was found in the extracellular milieu. Tryptase converted bovine prothrombin to thrombin, as shown by increase in thrombin activity with a synthetic substrate, t-butyloxy-carbonyl-Val-Pro-Arg-4-methyl-coumaryl-7-amide. The apparent Km value toward prothrombin was relatively low (2.3 microM), suggesting that tryptase contributes to blood coagulation or the process of fibrosis in tissues. The proteolytic products of IgG1 produced by chymase had chemotactic activity for neutrophil leukocytes in vitro and in vivo. These findings indicate the possible functions of these proteases after degranulation.
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PMID:Biological functions of serine proteases in the granules of rat mast cells. 354 4

Bacterial protein, staphylocoagulase, binds stoichiometrically to human prothrombin resulting in a coagulant complex, staphylothrombin. The enzymatic properties of staphylothrombin differ from those of alpha-thrombin in their substrate specificities toward natural and synthetic substrates, in addition to their interaction with protease inhibitors. In order to obtain information about the region of staphylocoagulase that interacts with human prothrombin, staphylocoagulase was cleaved by alpha-chymotrypsin. This limited alpha-chymotryptic cleavage of staphylocoagulase yielded three large fragments, fragments of 43, 30, and 20 kDa. The 43-kDa fragment exhibited a high affinity for human prothrombin (Kd = 1.7 nM), which is comparable to the affinity observed using intact staphylocoagulase (Kd = 0.46 nM). A complex of the 43-kDa fragment and prothrombin possessed both clotting and amidase activities essentially identical to those observed in a complex of intact staphylocoagulase and prothrombin. The 30-kDa fragment exhibited weaker affinity for prothrombin (Kd = 120 nM). While a complex of this fragment and prothrombin did not exhibit clotting activity, it nonetheless possessed a weak amidase activity. The 20-kDa fragment was found only to bind to prothrombin. The NH2-terminal sequence analyses of these fragments revealed that the 43-kDa fragment constitutes the NH2-terminal portion of staphylocoagulase, and contains the 30-kDa and 20-kDa fragments. It is therefore concluded that the functional region of staphylocoagulase for binding and activation of prothrombin is localized in the NH2-terminal region of the intact protein. The 43-kDa fragment contains 324 amino acids with a molecular weight of 38,098. The 43-kDa fragment has an unusual amino acid composition based on the sequence, in which the sum of Asp (28 residues), Asn (22), Glu (35), Gln (9), and Lys (52) residues accounts for more than 45% of the total residues. A comparison of the amino acid sequence of the 43-kDa fragment with that of streptokinase did not reveal any obvious sequence homology. There was also no sequence homology with those of trypsin, alpha-chymotrypsin, and elastase.
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PMID:Difference in enzymatic properties between "staphylothrombin" and free alpha-thrombin. 355 30

Structural studies on a hereditarily abnormal prothrombin, prothrombin Tokushima, have been performed to identify the difference responsible for its reduced fibrinogen clotting activity upon conversion to thrombin. The prothrombin sample used was from a heterozygote but contained exclusively a defective prothrombin molecule, since the patient was heterozygous for both dysprothrombinemia and hypoprothrombinemia. Amino acid sequence analysis of a peptide isolated from a lysyl endopeptidase digest of the abnormal thrombin indicated that Arg-418 (equivalent to Asn-101 in the chymotrypsin numbering system) had been replaced by Trp. This amino acid substitution can result from a single nucleotide change in the codon for Arg-418 (CGG----TGG). The Arg----Trp replacement found in the thrombin portion of prothrombin Tokushima appears to reduce its interaction with various substrates including fibrinogen and platelet receptors and accounts for the recurrent bleeding episode observed in the propositus.
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PMID:Prothrombin Tokushima, a replacement of arginine-418 by tryptophan that impairs the fibrinogen clotting activity of derived thrombin Tokushima. 356 58

Incubation of human platelets with unilamellar vesicles composed of dilauroylphosphatidylcholine (DLPC) induces shedding of small vesicular structures from the platelet plasma membrane. No significant cell lysis is observed during the process of shedding. Isolated spicules contain the major membrane glycoproteins, Ib, IIb, and IIIa, which are used to define the sidedness of the spicule membrane. These glycoproteins are completely susceptible to chymotrypsin treatment, whereas cytoskeletal proteins are inaccessible towards this enzyme. This demonstrates that the spicule membranes have a right-side-out orientation in as far as membrane proteins are concerned. Isolated spicules were 30-fold more active than platelets in stimulating prothrombin conversion to thrombin by the prothrombinase complex (factors Xa, Va and Ca2+). The increased prothrombinase activity reflects an increased amount of phosphatidylserine in the outer leaflet of the spicule membrane. Protein analysis of platelet spicules and native platelets reveals a number of differences, the most conspicuous of which is the virtual absence of myosin in the spicule preparations. It is proposed that a lack of myosin produces a different cytoskeletal organization in the spicules. This enables phosphatidylserine to become exposed at the outer surface of the spicule membrane.
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PMID:Loss of phospholipid asymmetry in dilauroylphosphatidylcholine induced plasma membrane vesicles from human platelets. 365 53

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

Platelet aggregation inducer and inhibitor were isolated from Echis carinatus snake venom. The venom inducer caused aggregation of washed rabbit platelets which could be inhibited completely by heparin or hirudin. The venom inducer also inhibited both the reversibility of platelet aggregation induced by ADP and the disaggregating effect of prostaglandin E1 on the aggregation induced by collagen in the presence of A23187, arachidonate, ADP and platelet-activating factor (PAF) with an IC50 of around 10 micrograms/ml. It did not inhibit the agglutination of formaldehyde-treated platelets induced by polylysine. In the presence of indomethacin or in ADP-refractory platelets or thrombin-degranulated platelets, the venom inhibitor further inhibited the collagen-induced aggregation. Fibrinogen antagonized competitively the inhibitory action of the venom inhibitor in collagen-induced aggregation. In chymotrypsin-treated platelets, the venom inhibitor abolished the aggregation induced by fibrinogen. It was concluded that the venom inducer caused platelet aggregation indirectly by the conversion of prothrombin to thrombin, while the venom inhibitor inhibited platelet aggregation by interfering with the interaction between fibrinogen and platelets.
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PMID:Action mechanism of the platelet aggregation inducer and inhibitor from Echis carinatus snake venom. 392 5

The primary structure of the procoagulant- and prothrombin-binding domains, the 43- and 30-kDa fragments previously isolated from staphylocoagulase, has been determined by sequencing peptides derived from various chemical (CNBr and 2-(2-nitrophenylsulfenyl)-3-methyl-3-bromoindolenine) and enzymatic (trypsin and alpha-chymotrypsin) cleavages. Carboxypeptidase Y was also used to deduce the COOH-terminal sequence. The 43-kDa fragment contained 324 amino acids and had a calculated molecular weight of 38,098. It included the entire structure of the 30-kDa fragment located in the COOH-terminal portion (positions 126-324). The 43-kDa fragment had an unusual amino acid composition based on the sequence, in which the sum of Asp (28 residues), Asn (22), Glu (35), Gln (9), and Lys (52) residues accounted for more than 45% of the total. In addition, the frequent occurrence of repetitions of the various kinds of dipeptides was found along the whole sequence. Structural comparison of the NH2-terminal portion of the 43-kDa fragment of staphylocoagulase with that of streptokinase did not reveal any obvious sequence homologies. There was also no sequence homology with that of trypsin, alpha-chymotrypsin, and elastase.
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PMID:The amino acid sequence of the procoagulant- and prothrombin-binding domain isolated from staphylocoagulase. 394 Oct 89

Several strains of Staphylococcus aureus secrete a protein, staphylocoagulase, that binds stoichiometrically to human prothrombin, resulting in a coagulant complex designated staphylothrombin. In the present study, staphylocoagulase was digested with alpha-chymotrypsin and the resulting fragments were isolated by gel filtration. One fragment (Mr 43,000) exhibited a high affinity for human prothrombin (Kd = 1.7 X 10(-9) M), which is comparable to the affinity observed using intact staphylocoagulase (Kd = 4.6 X 10(-10) M). A complex of the Mr 43,000 fragment and prothrombin possessed both clotting and amidase activity essentially identical to that observed in a complex of intact staphylocoagulase and prothrombin. A second fragment (Mr 30,000) exhibited weaker affinity for prothrombin (Kd = 1.2 X 10(-7) M). While clotting activity was not observed with a complex of this fragment and prothrombin, it nonetheless possessed a weak amidase activity. A third fragment (Mr 20,000) was found to bind to prothrombin, but the resultant complex did not exhibit clotting or amidase activity. Amino-terminal sequence analyses of these staphylocoagulase fragments revealed that the Mr 43,000 fragment constitutes the amino-terminal portion of staphylocoagulase and also contains the Mr 30,000 and 20,000 fragments. Moreover, the amino-terminal sequence of the Mr 20,000 fragment was identical to that observed for the Mr 30,000 fragment. From these results, we conclude that the functional region of staphylocoagulase for binding and activation of human prothrombin is localized in the amino-terminal region of the intact bacterial protein.
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PMID:Isolation and characterization of staphylocoagulase chymotryptic fragment. Localization of the procoagulant- and prothrombin-binding domain of this protein. 394 93

The entire amino acid sequence of complement factor B has been established combining both protein and DNA sequencing strategies. The zymogen consists of 739 amino acids, has four asparagine-linked carbohydrate sites, and has independently disulfide-bonded NH2- and COOH-terminal regions. The catalytic subunit, Bb, is a unique serine protease containing 259 amino acids that are not integral to any of the classical serine proteases. It is proposed that this region of the Bb fragment functions as a cofactor-binding domain for C3b. The Ba fragment was found to contain three regions of internal sequence homology which were unrelated to the "kringle" regions of prothrombin and plasminogen and which suggest an independent evolution for the B genome. Sequence alignment of the active site of B to the serine proteases was made using the three-dimensional structures of chymotrypsin and trypsin as molecular models. Three stretches within the hypothetical model for B contrast markedly with all known serine proteases in both amino acid sequences and predicted configuration. It is suggested that these "altered" regions contribute at least in part to the formation of the catalytic region of the C3 convertase.
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PMID:Complete primary structure for the zymogen of human complement factor B. 654 54

The gamma-carboxyglutamic acid (Gla)-domain region of factor X (residues 1-44 of the light chain) was selectively removed by limited proteolysis with alpha-chymotrypsin. The Gla-domainless factor X was then activated by the factor X coagulant protein of Russell's viper venom. Apparent dissociation constants Kd' values for the interaction of factor Va with either factor Xa or Gla-domainless factor Xa were determined kinetically using prothrombin as the substrate. In the absence of phospholipid, factor Va interacted with Gla-domainless factor Xa with lower affinity (Kd' 4 X 10(-6) M) than with factor Xa (Kd' = 5 X 10(-8) M). At saturating concentrations of factor Va, maximal rates of thrombin formation were similar for either enzyme. The addition of phospholipid increased the affinity of factor Va for factor Xa approximately 75-fold (Kd' = 3.3 X 10(-10) M). In contrast, phospholipid had no effect on the affinity of Gla-domainless factor Xa for factor Va (Kd' = 4 X 10(-6) M). The maximal rate of thrombin formation increased approximately 300-fold with the addition of phospholipid to the factor Xa-factor Va system. Under the same conditions, phospholipid had no effect on the rate of thrombin formation when Gla-domainless factor Xa was the enzymatic moiety. These results demonstrate phospholipid has little or no effect on factor Va function when factor Xa has lost its Gla-mediated Ca2+-binding sites.
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PMID:Comparison of coagulation factor Xa and des-(1-44)factor Xa in the assembly of prothrombinase. 669 66


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