Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.4.21.4 (trypsin)
 42,187 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Further evidence is presented that the acrosomal proteinase acrosin exists as a zymogen precursor in freshly ejaculated boar spermatozoa. Autoactivation of proacrosin to acrosin takes place optimally at slightly alkaline pH and in the presence of calcium ions. Activation is considerably accelerated by catalytic amounts of trypsin or highly purified acrosin. A significant acceleration of the activation is also achieved by porcine pancreatic and urinary kallikrein, whereas chymotrypsin, plasmin, thrombin or urokinase showed no effect. Activation can be inhibited by p-amino-benzamidine and p-nitrophenyl p'-guanidino-benzoate. Electrophoretic analysis at different stages of activation revealed that during this process various molecular forms of acrosin are produced, apparently by limited proteolysis.
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PMID:Multiple forms of boar acrosin and their relationship to proenzyme activation. 0 66

Two proteinases (2A and 2B) purified from the granular fraction of horse blood leucocytes degrade casein (Km values 12.8 and 6mg/ml respectively) with maximum activity at pH 7.4 and in the presence of 2m-urea. Urea-denatured haemoglobin, fibrinogen, albumin and resorcin/fuchsin-stained elastin are digested at a slower rate. The enzymes hydrolyse synthetic substrates of elastase, N-benzyloxycarbonyl-L-alanine 4-nitrophenyl ester (Km 0.114 and 0.178 mM) and N-acetyl-tri-L-alanine methyl ester (Km 5.55 and 0.98 mM), but they do not hydrolyse synthetic substrates of trypsin, chymotrypsin and thrombin. The examined proteinases are completely inhibited by 2 mM-di-isopropyl phosphorfluoridate and show a sensitivity to butyl and octyl isocyanates similar to that of pancreatic elastase. The pH-dependence of their photoinactivation in the presence of Rose Bengal indicates the presence of histidine in the active centre. Proteinase 2A rather insensitive to iodination by IC1 as is pancreatic elastase, whereas proteinase 2B is totally inactivated after incorporation of five iodine atoms per enzyme molecule.
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PMID:Substrate specificity and modifications of the active centre of elastase-like neutral proteinases from horse blood leucocytes. 0 9

Platelet-aggregating factor (PAF) was removed from bovine plasma by human platelets fixed with 2% formaldehyde. The degree of adsorption was directly related to the platelet concentration and the length of incubation. Fixed washed platelets (FWP) aggregated with bovine plasma could be deaggregated by 1M KCl, Evans blue, and 8M urea but not by beta-galactosidase. Incubation with 1M KCl eluted some but not all of the PAF, as the deaggregated platelets spontaneously aggregated upon removal of the deaggregating conditions. Also, fixed platelets adsorbed PAF even in the presence of 1M salt or after treatment with Evans blue. Platelet aggregation was not affected by thrombin (20 micron/ml) but was abolished by trypsin at concentrations as low as 4 X 10(-1) microgram/ml. The data suggest that deaggregation is not the result of elution of the loosely bound aggregating factor from the platelet surface, but rather the disruption of noncovalent interplatelet bridging between one or more PAF molecules bound to a specific receptor.
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PMID:Platelet-aggregating factor and the aggregation of fixed washed platelets. 1 45

For comparative studies on the esterase activities of thrombin and trypsin N(alpha)-arylsulfonyl-L-arginine methyl esters were synthetised containing in aromatic ring substituents of different polar nature, size and hydrophobicity. The kinetics of their hydrolysis by thrombin and trypsin were measured. Values of Km and kcat in steady-state conditions were determined. It was shown, that thrombin-catalysed hydrolysis was more sensitive than that of trypsin to the nature of substituents of arylsulfonyl group and determined by their polar and steric effects. A line correlation between specificity constants (kcat/Km) and sigma and Es of substituents were demonstrated. The difference in reactivity of compounds under investigation is suggested to depend on alterations of stability of hydrogen bond between arylsulfonylamide nitrogen atom of substrate and the active center of the enzyme due to changes in the acidity of the arylsulfonylamide group affected by substituent of the benzene ring.
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PMID:[Dependence of thrombin- and trypsin-catalyzed hydrolysis of N-alpha-arylsulfonyl-L-arginine methyl esters on the structure of acylamide part of substrates]. 2 Sep 97

p-Nitrobenzyl p-toluenesulfonyl-L-arginine is hydrolyzed by thrombin, plasmin, and trypsin to p-nitrobenzyl alcohol and tosyl-L-arginine. The absorption of p-nitrobenzyl alcohol formed is measured at 271 nm (AmM 8.89). With 0.10 mM of the ester in 0.1 M Tris-HCl at pH 8.4 and 30 degrees C, the hydrolysis catalyzed by thrombin, plasmin, and trypsin is linearly proportional to time up to consumption of 60% of the substrate. Km is 14 micron and Vmax is 0.037 mumol/min/NIH unit for bovine thrombin, Km is 78 micron and Vmax is 0.31 mumol/min/CTA unit/ml for human plasmin, and Km is 12 micron and Vmax is 138 mumol/min/mg protein/ml for bovine trypsin. Samples of bovine and human thrombin ranging in specific clotting activity from 59 to 2,133 NIH units/mg protein showed esterase activities ranging from 0.15 to 0.4 mumol p-nitrobenzyl alcohol formed/10 min/NIH unit. Useful ranges for assay of enzymes were (per milliliter): 0.05-0.2 NIH units (thrombin), 0.005-0.02 CTA units (plasmin), and 0.01-0.04 microgram (trypsin).
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PMID:p-Nitrobenzyl p-toluenesulfonyl-L-arginine: a chromogenic substrate for thrombin, plasmin and trypsin. 2 27

Mammary tumor cell growth factor(s) has been identified in extracts of platelets from both male and female rats, as well as in extracts prepared from pooled outdated human platelets. When assayed by the growth promotion of MTW9/PL rat mammary tumor cells in culture, platelet extracts alone were able to support growth 50--75% as well as whole serum. The mitogenic activity from crude human platelet lysates was shown to be trypsin sensitive, relatively stable to extremes of pH, labile to heat treatment at 70 degrees, non-dialysable, ammonium sulfate precipitable, not removed by 56 degrees charcoal treatment, and of apparent molecular weight of 30,000 to 50,000 daltons as estimated by G-100 Sephadex chromatography. The platelet derived mammary growth factor activity was not replaced or potentiated by thrombin or known hormones and growth factors such as prolactin, insulin, 17-beta-estradiol, progesterone, hydrocortisone, L-thyroxine, and mouse epidermal growth factor. The experimental report demonstrates that platelets are a rich source growth factor activity for rat epithelial mammary tumor cells, and that the activity appears to be a polypeptide(s) different from other mitogenic activities known to influence growth of mammary tissue.
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PMID:Platelet derived growth factor(s) for a hormone-responsive rat mammary tumor cell line. 3 Jul 82

The esterase action of thrombin and trypsin on N-arylsulfonyl-valyl-arginine methyl esters was studied. The values of Km and kcat under steady-state conditions at pH 8,5 were determined. It was shown that the nature of the arylsulfonyl group does not affect the kinetic parameters of the reactions under study. The Michaelis constants of the thrombin-catalyzed reactions appeared to be one order of magnitude lower than the Km values of the corresponding TAME analogs.
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PMID:[Comparative study of hydrolysis of methyl esters of N-arylsulfonyl-valyl-arginine by thrombin and trypsin]. 3 47

Some properties of protein inhibitor for trypsin (TI) from Act. janthinus 118 were studied. It was shown that TI has an antitrypsin activity within a wide pH range with a maximum at about 9,5. At 4 degrees and 20 degrees C TI is stable for 24 hours within the pH range of 6,0--11,0. At 100 degrees C TI is more stable in the slightly acid region of pH than at neutral or alkaline conditions. Trypsin and chymotrypsin inactivate the inhibitor for 8 hours. TI inhibits trypsin, fibrinolysin, subtilisin, pronase and terrilytin, but have no effect on chymotrypsin, thrombin, papain and pepsin. The dissociation constants for the trypsin-inhibitor complex were found to be 1,7.10-8 M, 4,1.10-9 M and 2,4.10-10 M, with casein, p-nitroanilide benzoylarginine and tosylarginine methyl ester used as substrates, respectively. The corresponding dissociation rate constants for the subtilisin-inhibitor complex were equal to 1.10-9 M and 4.10-10 M with casein and carbobenzoxy-L-alanyl-L-alanyl-L-leucin p-nitroanilide used as substrates, respectively.
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PMID:[Stability and specificity of extracellular protein inhibitor for trypsin from Actinomyces janthinus 118]. 3 28

Thrombin converts fibrinogen to fibrin monomer by cleaving fibrinopeptides A and B (FPA and FPB) from the amino terminal ends of the A (alpha) and B (beta) chains. A radioimmunoassay capable of measuring the A peptide in human blood as an index of thrombin action in vivo has been described previously. This paper describes the development of a radioimmunoassay for FPB and the use of both assays in the demonstration of distinctive patterns of cleavage of the amino terminal ends of the A (alha) and B (beta) chains of fibrinogen by various enzymes. Antisera were raised in rabbits to a synthetic analogue of FPB coupled to bovine serum albumin. FPB analogue was couple to desaminotyrosine and radiolabeled with 125I by the chloramine-T technique. The radiolabeled peptide was bound by the antiserum, and binding was inhibited by synthetic or native FPB. Unbound tracer was separated from bound tracer by charcoal adsorption. The senistivity of the assay was such that 50% inhibition of binding of the tracer was caused by 1.25 ng of the native FPB. Fibrinogen was treated with thrombin, plasmin, trypsin, Reptilase, and an extract of the venom from Ancistrodon contortrix contortrix (ACC). After ethanol precipitation and centrifugation, dialysates of enzymatically altered fibrinogen were assayed for FPA and FPB. The action of thrombin on fibrinogen resulted in a rapid release of FPA and a slower release of FPB. Plasmin cleaved a segment(s) of the B (beta) chain which included FPB but cleaved no detectable FPA-containing material for the first 2 h of incubation. In the case of plasmin-treated fibrinogen, the dialysates had been further treated with thrombin before being assayed for FPA and FPB. Trypsin rapidly cleaved both peptides, the B before the A. Reptilase cleaved only FPA in 24 h. ACC cleaved FPB at a rapid rate, with a slowere cleavage of FPA. The distinctive cleavage patterns produced by the serine proteases may be useful in interpreting the levels of FPA and FPB measured in human blood and in studying the generation of FPA and FPB in clinical blood samples.
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PMID:Radioimmunoassay of human fibrinopeptide B and kinetics of fibrinopeptide cleavage by different enzymes. 5 Mar 28

Antithrombin activity has been identified in intact washed human platelets. An apparent activity was demonstrated at platelet concentrations above 0.31 X 10(9)/ml, when platelet suspensions were incubated with 2.0 NIH units/ml of thrombin. Neither red cells nor white cells revealed antithrombin activity. No significant loss of the platelet antithrombin activity was observed after ten successive washings or after treatment of platelets with antibodies to antithrombin III or alpha2-macroglobulin. Almost the same amount of antithrombin activity as normal platelets was demonstrated in the platelets from an afibrinogenemic patient. Pre-treatment of platelets with trypsin, papain, and neuroaminidase reduced the activity significantly, whereas lipase was without effect. The platelet antithrombin reacted with thrombin in less than 3 seconds, and this rapid reaction of platelet antithrombin was different from that of plasma antithrombin III or fibrinogen. The thrombin-like clotting activity of ancrod was inhibited by fibrinogen but not platelets. Also, unlike plasma antithrombin III or fibrinogen, brief exposure to heat (56 degrees C or 60 degrees C) reduced considerable amounts of platelet antithrombin activity. These results suggest that platelets possess a specific antithrombin with different characteristics from other known antithrombins.
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PMID:Antithrombin activity of intact human platelets. 5 97


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