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)

Two radiochemical esterolytic assays for urokinase are described. One assay is based on the urokinase-dependent hydrolysis of Nalpha-acetyl-glycyl-L-lysine [3H]methyl ester and the other on the urokinase-dependent activation of plasminogen and assay of generated plasmin with Nalpha-tosyl-L-arginine [3H]methyl ester. The assays are performed in tubes placed in liquid scintillation counting vials. At the end of the experiment generated [3H]methanol is extracted into the liquid scintillation cocktail and counted. Unhydrolyzed substrate largely remains in the aqueous phase and contributes only a small fraction of the counts. This facile separation of 3H-labeled alcohol from the ester substrate allows the simple and highly sensitive assay for urokinase. The assays give results in good agreement with the classical fibrin plate assay.
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PMID:Sensitive radiochemical esterolytic assays for urokinase. 0 14

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

Urokinase (UK) and streptokinase (SK) transform plasminogen into plasmin by rupture of a ARG-VAL bond and the liberation of a peptide with a molecular weight of 6000 to 8000. Urokinase is a physiological activator with a direct action. By contrast, streptokinase is an enzyme of bacterial origin and two hypotheses may be advanced to explain its mechanism of action: the formation of a SK-plasminogen complex capable of activatiing new molecules of plasminogen or the formation of a SK-plasminogen complex within which plasminogen is transformed to plasmin.
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PMID:[Enzymatic fibrinolytic agents]. 3 Nov 12

The steady-state kinetics of plasmin- (EC 3.4.21.7) and trypsin-catalysed (EC 3.4.21.4) hydrolysis of Bz-L-Phe-Val-Arg-pNA, Bz-D-Phe-Val-Arg-pNA, L-Phe-Val-Arg-pNA, D-Phe-Val-Arg-pNA and D-Val-Leu-Lys-pNA were investigated in the pH range 6-9. The pH dependences of the kinetic parameters correspond with the effects of catalytically essential ionizations in the enzymes, except for reactions with L- and D-Phe-Val-Arg-pNA, in which protonation of the NH2-terminal alpha-amino groups (pK = 7.0) shows some inhibitory effect. The reactions of plasmin and trypsin with p-nitroanilides show kc values similar to those normally found with specific ester substrates, indicating that the deacylation steps of the reactions are rate determining.
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PMID:Steady-state kinetics of plasmin- and trypsin-catalysed hydrolysis of a number of tripeptide-p-nitroanilides. 3 47

Porcine plasmin (EC 3.4.21.7) is obtained from plasminogen activated by human urokinase. This enzyme can bind, in an equimolecular ratio, to an alpha2-macroglobulin isolated from porcine serum. The number of active sites of plasmin has been determined through a burst titration of nitroaniline during the presteady-state hydrolysis of an amide substrate (N-alpha-carbobenzoxy-L-arginine-p-nitroanilide). The kinetic constants relative to a very sensitive ester substrate (N-alpha-carbobenzoxy-L-lysine nitrophenylester) hydrolysis have been measured. The binding of plasmin to alpha2-macroglobulin results in a complete inhibition of proteolytic activity, a reduction of active sites number and a decrease of esterolytic activity towards this substrate. In the complex, the residual activity (about 60%) is protected from protein inhibitors. Absorbance difference spectra show that 1 mol of alpha2-macroglobulin binds 1 mol of plasmin and 2 mol of trypsin. When plasmin is first bound to alpha2-macroglobulin, only 1 mol of trypsin can gain access tothe second site without removing the plasmin, showing that a steric hindrance is implicated in the inhibition performed by alpha2-macroglobulin binding.
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PMID:[Study of the complex between porcine plasmin and alpha2-macroglobulin (author's transl)]. 5 8

The autodigestion of plasmin in neutral solution at 37 degrees C and prevention of plasmin autodigestion by methylamine were confirmed by using rho-Tosyl-L-Arginine-Methyl ester as a substrate of plasmin. The autodigestion of plasmin was prevented by human plasma alpha2-macroglobulin which has been reported as an antiplasmin of immediate and reversible type but was not prevented by alpha1-antitrypsin which has been reported as an antiplasmin of slow and irreversible type.
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PMID:Prevention of plasmin autodigestion by human plasma alpha2-macroglobulin. 7 56

Protease-like activity which split plasminogen-free fibrin was demonstrated in 2 M KSCN extracts of the lung and spleen of conventional rats. The activity was virtually undetectable in tissue extracts from germ-free rats. The extracts from the conventional rat tissues split fibrin and fibrinogen remarkably at neutral pH, but not casein, when examined using fibrin, fibrinogen-agar and casein-agar plates. The fibrinolytic activity was inhibited by STI and DFP, indicating a serine protease nature. The activity was not inhibited by TLCK, t-AMCHA or dansyl-L-arginine-methylpiperidine amide (a selective synthetic thrombin inhibitor, OM189). It was neither activated nor inhibited by cysteine, KCN or iodoacetic acid. The results obtained indicate that the protease-like activity of the lung and spleen extracted with 2 M KSCN from conventional rats has properties which differ from those of trypsin, plasmin, plasminogen-activator, thrombin, and cathepsin A, B and C.
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PMID:Fibrinolytic activity of lung and spleen extracts observed in conventional but not in germ-free rats. 9 68

Alpha 2 acute-phase macroglobulin was isolated from plasma of turpentine-injected rats. In the method conditions known to damage the biological activities of alpha 2 macroglobulin are avoided. The procedure successively involves: rivanol precipitation, concanavalin A-Sepharose chromatography and ion-exchange chromatography on DEAE-cellulose. Proteolytic activities were minimized throughout the purification. Thus alpha 2 macroglobulin was obtained in a 20% yield and was pure by biochemical and immunological criteria. Its molecular weight appeared to be 760 000 and it consisted of four subunits (Mr 190 000). The protein has an A1cm 1% = 8.8 and an isoelectric point = 4.8. The amino acid and carbohydrate compositions were determined. Our preparations bound 1 molecule of trypsin or 1 molecule of plasmin/molecule of alpha 2 macroglobulin. Kinetic parameters for alpha 2 macroglobulin-bound trypsin and plasmin were determined and compared with those of free trypsin and plasmin using butoxycarbonyl-L-valylglycyl-L-arginine-2-naphthylamide and benzoyl-L-arginine ethylester as substrates.
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PMID:Purification and properties of rat alpha 2 acute-phase macroglobulin. 9 34

Nerve growth factor is a highly specific protease that can convert plasminogen to plasmin and that can hydrolyze certain synthetic N-substituted arginine esters (e.g., Nalpha=p-toluenesulfonyl-L-arginine methyl ester (TAME); N.S. Orenstein et al. (1978) Proc. Natl. Acad. Sci. U.S.A. 75, 5497). Hydrolysis of TAME is characterized by a lag phase of lower velocity which precedes development of the steady-state maximal velcity. Kinetic analyses indicate that this behavior stems from autocatalytic activation of a nerve growth factor (NGF)-zymogen by NGF. As isolated from the mouse submandibular gland at high concentration, NGF is largely enzymically inactive. Upon high dilution, the protein undergoes autocatalytic activation with concomitant generation of full enzymic activity. The biologic significance of this unusual property of NGF is not clear, but it may serve to prevent expression of enzymic activity until the protein reaches its target cell(s) or until it recognizes its physiological substrate.
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PMID:Proteolytic activity of nerve growth factor: a case of autocatalytic activation. 11 9

The carboxy-terminal cyanogen bromide fragment of the human fibrinogen beta-chain has been isolated and its structure determined. It is a nonapeptide with the sequence Lys-Ile-Arg-Pro-Phe-Phe-Pro-Gln-Gln and is homologous with a portion of the carboxy-terminal cyanogen bromide fragment of the gamma-chain. The peptide has also been isolated in full yield from cyanogen bromide digests of the plasmin-derived fragment D, indicating that the carboxy-terminal region of the beta-chain is resistant to plasmin digestion. In contrast, a small portion of the corresponding gamma-chain carboxy-terminal region was missing in the same fragment D.
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PMID:Amino acid sequence of the carboxy-terminal cyanogen bromide peptide of the human fibrinogen beta-chain: homology with the corresponding gamma-chain peptide and presence in fragment D. 12 85


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