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 inhibition of plasmin, (EC 3.4.21.7), thrombin (EC 3.4.21.5), trypsin (EC 3.4.21.4) and chymotrypsin (EC 3.4.21.1) by antiplasmin, the recently described fast-reacting plasmin inhibitor of human plasma, was studied. To determine the quantitative importance of antiplasmin relative to the other plasma protease inhibitors, enzyme inhibition assays were performed on whole plasma and on plasma specifically depleted in antiplasmin, after addition of excess enzyme. Plasmin was the only enzyme for which the inhibitory capacity of antiplasmin-depleted plasma was lower than that of normal plasma. To determine the affinity of the enzymes for antiplasmin, as compared to the other inhibitors, various amounts of enzymes were added to normal plasma and the formation of enzyme-antiplasmin complexes studied by crossed immunoelectrophoresis using specific antisera against antiplasmin. Plasmin and trypsin, but not thrombin or chymotrypsin formed complexes with antiplasmin. It is concluded that antiplasmin is the only fast-reacting plasmin inhibitor of human plasma. It is also a fast-reacting inhibitor of trypsin but only accounts for a very small part of the fast-reacting trypsin-inhibitory activity of plasma. This can be explained by the low concentration of antiplasmin (1 muM) in normal plasma, compared to the other inhibitors (e.g. alpha1-antitrypsin: 40-80 muM).
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PMID:The interaction in human plasma of antiplasmin, the fast-reacting plasmin inhibitor, with plasmin, thrombin, trypsin and chymotrypsin. 14 66

Plasmin inhibited the biosynthesis of tissue-type plasminogen activator (tPA) antigen by human umbilical vein endothelial cells (HUVEC) in a dose-dependent manner. The amount of tPA antigen found in the 24-h conditioned medium of cells treated with 100 nM plasmin for 1 h was 20-30% of that in the control group. However, in contrast to tPA, such treatment led to a 3-fold increase in plasminogen activator inhibitor (PAI) activity, whereas the amount of PAI type 1 antigen was unchanged. The effects of plasmin on HUVEC were binding- and catalytic activity-dependent and were specifically blocked by epsilon-aminocaproic acid. Microplasmin, which has no kringle domains, was less effective in reducing tPA antigen biosynthesis or enhancing PAI activity in HUVEC. Kringle domains of plasmin affected neither tPA antigen nor PAI activity of the cells. Other proteases including chymotrypsin, trypsin, and collagenase at comparable concentrations did not have a significant effect on the biosynthesis of tPA antigen or PAI activity of HUVEC. Thrombin stimulated the biosynthesis of tPA and PAI-1 antigens by HUVEC. Thrombin also stimulated an increase in the protein kinase activity in HUVEC, whereas plasmin inhibited the protein kinase activity of the cells. It is possible that plasmin regulates the biosynthesis of tPA in HUVEC through the signal transduction pathway involving protein kinase.
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PMID:Plasmin and the regulation of tissue-type plasminogen activator biosynthesis in human endothelial cells. 138 68

The effects of bolus intravenous injections of various serine proteases (thrombin, trypsin, plasmin, neutrophil elastase and chymotrypsin) on arterial blood pressure were evaluated in anesthetized, normotensive rats. The activity to intravenous trypsin was also studied in anesthetized, normotensive dogs. In the rat, both thrombin (0.33-10 nmol/kg) and trypsin (4.2-420 nmol/kg) produced pronounced vasodepressor responses. The activity on blood pressure was observed immediately following injection of either protease, and both the magnitude and duration of the responses were dose dependent. Plasmin (37-350 nmol/kg) and neutrophil elastase (91-910 nmol/kg) also induced dose-dependent hypotension but at much higher dose levels. In addition, the magnitude of the blood pressure responses after plasmin and neutrophil elastase was less than those produced by thrombin and trypsin. Chymotrypsin, on the other hand, had a more diverse blood pressure profile. The protease induced a modest decrease in pressure at doses of 40 and 120 nmol/kg, a pressor response after 400 and 1,200 nmol/kg and at the highest dose tested (4,000 nmol/kg) profound hypotension. In the dog, trypsin produced a dose-dependent vasodepressor response similar to that observed in the rat. The doses of proteases producing alterations of blood pressure in the rat correlated inversely with the ability of rat serum or plasma to completely inhibit those proteases. The pharmacology of the trypsin or thrombin blood pressure response suggests the requirement of specific active enzymes to mediate the vasodepression induced by both proteases.
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PMID:Acute blood pressure effects of selected serine proteases in normotensive rats and dogs. 177 Nov 72

Interstitial collagenases (matrix metalloproteinase-1, EC 3.4.24.7), isolated from extracts of inflamed human gingiva, gingival crevicular fluid and saliva were characterized for their molecular weight, proteolytic and non-proteolytic activation and substrate specificity against soluble collagen types I, II and III. All three collagenases had Mr of 70 K. The enzymes existed predominantly in a latent form that could be activated by aminophenylmercuric acetate, gold thioglucose and hypochlorous acid. Among serine proteases tested, trypsin, chymotrypsin, neutrophil cathepsin G and a combination of trypsin and human gingival fibroblast prostromelysin activated gingival and salivary interstitial collagenases. Plasmin and plasma kallikrein, however, were relatively ineffective activators. The collagenases degraded soluble type I and II collagens at apparently equal rates but considerably faster than they did type III collagen. These findings suggest that the characteristics of interstitial collagenases found in inflamed human gingiva, gingival crevicular fluid and saliva are consistent with those of human neutrophil interstitial collagenase rather than the fibroblast-type interstitial collagenase. Thus, neutrophils are suggested to be the main source of such enzymes in inflamed human gingiva, crevicular fluid and saliva during adult periodontitis.
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PMID:The role of gingival crevicular fluid and salivary interstitial collagenases in human periodontal diseases. 196 17

Plasmin was recently reported to inhibit platelet aggregation. We report here on the interaction of plasmin with the adenylate cyclase system of human platelets. Human plasmin caused a dose- and time-dependent increase in adenylate cyclase activity when added to a crude platelet membrane preparation. Both basal and prostaglandin E1-stimulated adenylate cyclase activity doubled in presence of plasmin. This stimulatory activity was shared by papain and alpha-chymotrypsin, but not by thrombin which displayed a slightly inhibitory effect. Plasmin not only stimulated platelet adenylate cyclase activity, but also suppressed the GTP-dependent alpha 2-adrenergic inhibition, thereby producing a five- to six-fold increased activity measured in the presence of adrenaline and GTP. These effects of plasmin on the adenylate cyclase system were suppressed by the addition of the protease inhibitor leupeptin, and of soybean trypsin inhibitor, indicating that proteolysis mediated these effects. We also examined the adenylate cyclase activity in membranes prepared from intact platelets incubated with increasing doses of plasmin. Incubation of platelets with plasmin concentrations as low as 0.25 mg/ml resulted in an irreversible increase in membrane adenylate cyclase activity and suppression of the adrenaline-mediated inhibition of enzyme activity. These results suggest that the proteolytic stimulating effect of plasmin on the platelet adenylate cyclase system may account for the inhibition of platelet aggregation.
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PMID:Plasmin: a possible physiological modulator of the human platelet adenylate cyclase system. 295 Oct 52

A versatile, convenient assay for vertebrate collagenases has been developed using the fluorescent peptide substrate dansyl-Pro-Gln-Gly-Ile-Ala-Gly-D-Arg. This sequence resembles that of collagen at the site of cleavage but includes modifications designed to eliminate nonspecific hydrolysis by contaminating peptidases. Both human skin fibroblast and bovine corneal cell collagenases cleave the substrate specifically at the Gly-Ile bond. Plasmin, thrombin, trypsin, alpha-chymotrypsin, carboxypeptidase B, and bacterial collagenase do not cleave the substrate. Elastase and angiotensin converting enzyme display 20- and 400-fold less activity than the vertebrate collagenases, respectively, and cleave the peptide at different positions. The assay is performed by incubating a 5- to 25-microliters aliquot of trypsin-activated sample with an equal volume of 2 mM substrate overnight at 33 degrees C and pH 7.5. Thin-layer chromatography then separates the fluorescent product from the substrate in less than 20 min and allows the detection of subnanogram levels of collagenase. The assay is applicable to the screening of large numbers of samples under different conditions of pH and ionic strength and is readily adaptable for use in a variety of collagenase-dependent systems, such as assays for collagenase activating and/or inducing factors.
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PMID:A convenient fluorescent assay for vertebrate collagenases. 301 20

Plasmin preferentially cleaves rabbit hemopexin at a single site, generating two nondisulfide-linked carbohydrate-containing fragments. In contrast, heme-hemopexin is almost totally resistant to this enzyme and is more resistant than the apoprotein to digestion by trypsin, chymotrypsin, papain, subtilisin, and proteinase K as well. Plasmin digestion dramatically shortens the plasma clearance time of the molecule. The larger glycopeptide (I), shown to be derived from the amino terminus of the parent molecule by sequence analysis, has a molecular weight near 35,000 with a pI of 5.0. It binds 1 mol of heme per mol in a manner analogous to intact hemopexin, molecular weight near 60,000 and pI 5.8. The smaller glycopeptide (II) has a molecular weight near 25,000, a pI of 6.4, and does not bind heme. Of the four oligosaccharides of rabbit hemopexin, peptide I contains three oligosaccharides and peptide II contains one. At micromolar concentrations, the two peptides migrate together during centrifugation through sucrose gradients in the presence, but not in the absence, of heme. Peptide I has a far UV circular dichroism spectrum indicating it has some alpha-helical and extensive nonrepeating peptide structures whereas peptide II appears to be almost exclusively in a beta-sheet conformation. Peptide II is responsible for most of the positive ellipticity at 231 nm of native apohemopexin, but the increase in ellipticity at 231 nm characteristic of heme-hemopexin is not seen when peptide I binds heme, even in the presence of peptide II.
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PMID:Domain structure of rabbit hemopexin. Isolation and characterization of a heme-binding glycopeptide. 623 5

We have examined the effects of seven proteases on human placental tissue factor in Triton X-100, focusing on extracellular and cytoplasmic domains recognized by monoclonal antibodies HTF1, C28 1.1, and C28 2.1. Plasmin produced peptides recognized on Western blots by C281.1 but not HTF1. None of the other proteases destroyed the extracellular epitope without also removing the cytoplasmic epitope, and both trypsin and chymotrypsin removed the cytoplasmic epitope with little effect on the extracellular domain. Proteinase K destroyed both epitopes, as did neutrophil elastase when used at a relatively high concentration. When digests were sampled over time and reconstituted with lipids for determination of tissue factor activity, only proteinase K consistently produced a loss in tissue factor activity at four hours. After 24 hr, other enzymes also decreased the recovered activity, with the order of effectiveness elastase > trypsin > chymotrypsin.
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PMID:Human placental tissue factor: protease susceptibility of extracellular and cytoplasmic domains. 750 71

Unlike most proteases, tissue-type plasminogen activator (t-PA) is secreted from cells as an active, single chain "proenzyme" whose catalytic efficiency is comparable with that of the corresponding mature, two-chain enzyme. We have previously suggested that the absence of the "zymogen triad" (Asp194-His40-Ser32; chymotrypsin numbering) contributes to this unusually high enzymatic activity of single chain t-PA. Consistent with this prediction, the single chain form of a variant of t-PA containing the zymogen triad displayed dramatically reduced activity toward synthetic substrates. Activation cleavage of this variant, however, resulted in a mature, two-chain enzyme with full catalytic activity. To further examine the functional significance of the zymogen triad, we used site-specific mutagenesis to construct a variant of t-PA, t-PA/R275E,A292S,F305H, that contained this triad but could not be converted into its two-chain form by plasmin. Characterization of this variant demonstrated that the presence of the zymogen triad specifically suppressed plasminogen activation by single chain t-PA in the absence of fibrin. In addition, these studies indicated that, like wild type t-PA, zymogen activation of this variant could be accomplished by binding to the co-factor fibrin. The combination of full activity in the presence of fibrin and reduced activity in its absence resulted in novel variants of t-PA that displayed dramatically enhanced stimulation by fibrin. While the presence of fibrin increased the catalytic efficiency of t-PA toward plasminogen by a factor of approximately 520, this stimulation factor increased to 130,000 for t-PA/R275E,A292S,F305H. Plasmin-resistant, zymogen-like variants of t-PA, therefore, may represent thrombolytic enzymes with enhanced "clot selectivity."
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PMID:Variants of tissue-type plasminogen activator which display substantially enhanced stimulation by fibrin. 762 53

An inhibitor of pancreatic elastase (EI), which can also inhibit chymotrypsin, and an inhibitor of trypsin (TI), which can also inhibit plasmin, have been isolated from bovine plasma. EI and TI belong to the serpin family of inhibitors. The size of both inhibitors is approx. 60 kDa and they are able to form SDS-stable complexes with proteinases. Curiously, TI dimerizes in the presence of SDS, a feature which has been observed previously only in non-denaturing gels of human alpha 1-antitrypsin (alpha 1PI). EI and TI are glycosylated [16% and 19% (w/w) respectively] and their amino acid compositions are similar to those of other plasma serpins. Neither EI nor TI is the equivalent of bovine alpha 1PI, as revealed by partial sequence analysis of their N-termini and reactive sites. Rather, both inhibitors appear to be related to human alpha 1-antichymotrypsin. Inhibition of pancreatic elastase and chymotrypsin by EI occurs with a kass. approximately 10(5) M-1.s-1. TI inhibits trypsin with a kass. approximately 10(5) M-1.s-1. Plasmin is inhibited by TI with a kass. approximately 10(3) M-1.s-1. The values of the kinetic constants are similar to those determined for the well-studied human serpins. Antibodies to EI and TI reveal a set of four antigenically related proteins of similar size in plasma. In addition, they detect the same set of proteins in milk. The inhibitors isolated from milk are identical to EI and TI from plasma. EI could control the activity of chymotrypsin-like proteinases in milk. In contrast, no target proteinases of TI in milk can be suggested.
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PMID:Characterization of two serpins from bovine plasma and milk. 798 Mar 96


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