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:3.4.21.7 (plasmin)
9,023 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A new method to determine plasmaprokallikrein independently of its inhibitors is described. By ion exchange chromatography with DEAE-A-50 Sephadex plasmaprokallikrein can be separated from its inhibitors Cl-esterase inhibitor, alpha 2-macroglobulin, alpha 1-antitrypsin (protease inhibitor) and antithrombin III as well as from other enzymes like plasmin, Hagemann factor and glandular kallikrein, which can interfere with the chromogenic substrate of the amidolytic assay (S 2302) used to determine plasmakallikrein activity. Furthermore, this method also allows the measurement of plasmaprokallikrein in heparinized plasma, since heparin was separated by this chromatography technique from plasmaprokallikrein too. The enzymatic activity of activated plasmakallikrein was not changed by the ion exchange chromatography. Normal values of the plasmaprokallikrein content in plasma were in the range of 2.57 +/- 0.12 U/ml of plasma (n:42; X +/- SEM). No influence on plasmaprokallikrein activity of age and sex was found.
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PMID:Measurement of plasma prokallikrein independent of inhibitors and interfering enzymes. 364 44

Although Cl-inhibitor (Cl-INH) and alpha(2)-macroglobulin (alpha(2)M) have been reported as the major inhibitors of plasma kallikrein in normal plasma, there is little quantitative support for this conclusion. Thus, we studied the inactivation of purified kallikrein in normal plasma, as well as in plasma congenitally deficient in Cl-INH, or artificially depleted of alpha(2)M by chemical modification of the inhibitor with methylamine. Under pseudo-first-order conditions, the inactivation rate constant of kallikrein in normal plasma was 0.60 min(-1). This rate constant was reduced to 0.35, 0.30, and 0.06 min(-1), in plasma deficient respectively in Cl-INH, alpha(2)M, or both inhibitors. Thus Cl-INH (42%) and alpha(2)M (50%) were found to be the major inhibitors of kallikrein in normal plasma. Moreover all the other protease inhibitors present in normal plasma contributed only for 8% to the inactivation of the enzyme. To confirm these kinetic results, (125)I-kallikrein (M(r) 85,000) was completely inactivated by various plasma samples, and the resulting mixtures were analyzed by gel filtration on Sepharose 6B CL for the appearance of (125)I-kallikrein-inhibitor complexes. After inactivation by normal plasma, 52% of the active enzyme were found to form a complex (M(r) 370,000) with Cl-INH, while 48% formed a complex (M(r) 850,000) with alpha(2)M. After inactivation by Cl-INH-deficient plasma, >90% of the active (125)I-kallikrein was associated with alpha(2)M. A similar proportion of the label was associated with Cl-INH in plasma deficient in alpha(2)M. After inactivation by plasma deficient in both Cl-INH and alpha(2)M, (125)I-kallikrein was found to form a complex of M(r) 185,000. This latter complex, which may involve antithrombin III, alpha(1)-protease inhibitor, and/or alpha(1)-plasmin inhibitor, was not detectable in appreciable concentrations in the presence of either Cl-INH or alpha(2)M, even after the addition of heparin (2 U/ml). These observations demonstrate that Cl-INH and alpha(2)M are the only significant inhibitors of kallikrein in normal plasma confirming previous predictions based on experiments in purified systems. Moreover, in the absence of either Cl-INH or alpha(2)M, the inactivation of kallikrein becomes almost entirely dependent on the other major inhibitor.
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PMID:Contribution of plasma protease inhibitors to the inactivation of kallikrein in plasma. 617 99

Paired plasma and synovial fluids from 17 patients with seropositive rheumatoid arthritis were examined for electrophoretic homogeneity/heterogeneity and enzymic inhibitory capacity of the protease inhibitors. The high degree of saturation (approximately 90%) of the polyvalent protease inhibitor alpha 2-macroglobulin in the rheumatoid synovial fluid contrasts sharply with the low saturation of alpha 1-anti-trypsin. The inhibitory reactivity of the non-complexed fraction of both of these dominating antiproteases was retained (approximately 85-90%). Thus, a selective inactivation of synovial alpha 1-antitrypsin could not be demonstrated. alpha 1-Anti-chymotrypsin revealed electrophoretic homogeneity in all synovial fluids. Electrophoretic heterogeneity of the plasmin inhibitor antiplasmin was detected in the majority of synovial fluids indicating plasmin activation. The existence of a protease-antiprotease imbalance in the rheumatoid joint was indicated by the high degree of saturation of alpha 2-macroglobulin and a cleavage of C3 in rheumatoid synovial fluids.
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PMID:Protease inhibitors in rheumatoid synovial fluid. Analyses of electrophoretic homogeneity and protease inhibitory capacity. 618 71

FUT-175 (6 amidino-2-naphthyl-4-guanidino benzoate-dimethanesulfonate), a new synthetic protease inhibitor, inhibits the enzyme activities of various proteases, such as Clr, C1 esterase, thrombin, kallikrein, plasmin and trypsin. FUT-175 strongly inhibited complement-medicated hemolysis via the classical and alternative pathways. The effects of FUT-175 on various immunological reactions in vivo were studied. The minimal effective dose of FUT-175 in systemic Forssman shock in guinea pigs was 6.25 mg/kg i.p. and 25 mg/kg p.o. In passive Arthus reactions in rats, the effective dose was 25 mg/kg i.p. and 250 mg/kg p.o. FUT-175 also inhibited other immunological reactions, such as passive cutaneous anaphylaxis and delayed hypersensitivity. Furthermore, at a dose of 25 mg/kg i.p. it strongly protected mice from death in endotoxin shock.
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PMID:Inhibition of various immunological reactions in vivo by a new synthetic complement inhibitor. 621 61

Tumor-promoting phorbol esters have been reported to greatly increase plasminogen activator (PA) activity produced in numerous cell types. Many of these studies have employed a widely used fibrinolysis assay for PA activity that involves large-scale dilution of cell lysates or conditioned medium (CM) into buffer containing plasminogen and the plasmin substrate 125I-fibrin. This assay indicates that phorbol ester and the mitogens epidermal growth factor (EGF) and thrombin all stimulate secretion of PA activity in our human foreskin fibroblast cultures. However, these effects are not observed in a modified fibrinolysis assay employing undiluted conditioned culture medium unless the medium is first treated at pH 3, which inactivates the secreted protease inhibitor, protease nexin (PN). Moreover, a direct assay for plasminogen activator activity based on cleavage of 125I-plasminogen indicates that conditioned culture medium contains little if any active plasminogen activator either before or after treatment of the cultures with phorbol ester or EGF. Phorbol ester and mitogens do stimulate secretion of (a) an inactive PA that can be activated by plasmin and (b) PN, which inhibits both the activated form of the PA and plasmin. Secretions of the inactive PA and PN are further correlated in that release of both is stimulated most by phorbol ester, somewhat less by EGF, and least by thrombin. Significantly, these effects are not accompanied by increases in total protein secretion. We propose that fibroblasts secrete PA in an inactive form in the presence of PN to confine PA activity to an as yet undefined location or event.
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PMID:Phorbol ester and mitogens stimulate human fibroblast secretions of plasmin-activatable plasminogen activator and protease nexin, an antiactivator/antiplasmin. 622

An acid-stable protease inhibitor (AS-PI) has been previously demonstrated in ascitic fluid from patients with ovarian carcinoma. In this study, the AS-PI was further purified using DEAE-cellulose and isoelectric focusing (IEF), and a partial characterization was undertaken. On DEAE-cellulose ion-exchange column chromatography, AS-PI activity was observed in both adsorbed and non-adsorbed fractions. The former represented the main AS-PI peak. By IEF, the respective pI values were 1.6 and 4.5. By gel filtration, the molecular weight of the main (adsorbed fraction) AS-PI was 78 000. This AS-PI strongly inhibited trypsin and to a lesser extent chymotrypsin, but exerted no inhibitory effect on plasmin. It slightly inhibited SH proteases such as papain and ficin. Immunologically, AS-PI was distinct from alpha 1-antitrypsin, alpha 1-antichymotrypsin, inter-alpha-trypsin inhibitor, antithrombin III, C1-inactivator, alpha 2-macroglobulin and alpha 2-plasmin inhibitor. The main AS-PI reacted with and was neutralized by antiurinary trypsin inhibitor serum, and on immunoelectrophoresis, had a mobility slightly cathodal to serum albumin.
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PMID:Further purification and characterization of acid-stable protease inhibitor from ascites of an ovarian carcinoma patient. 643 8

The kinetics of inhibition of four hemostatic system enzymes by antithrombin were examined as a function of heparin concentration. Plots of the initial velocity of factor Xa-antithrombin or plasmin-antithrombin interaction versus the level of added mucopolysaccharide exhibit an ascending limb and subsequent plateau regions. In each case, the kinetic profile is closely correlated with the concentration of the heparin . antithrombin complex formed within the reaction mixture. A decrease in the velocity of inhibition is not observed at high levels of added mucopolysaccharide despite the generation of significant quantities of heparin-enzyme interaction products. The second-order rate constants for the neutralization of factor Xa or plasmin by the mucopolysaccharide . inhibitor complex are 2.4 x 10(8) M-1 min-1 and 4.0 x 10(6) M-1 min-1, respectively. These parameters must be contrasted with the similarly designated constants obtained in the absence of heparin which are 1.88 x 10(5) M-1 min-1 and 4.0 x 10(4) M-1 min-1, respectively. Plots of the initial velocity of the factor IXa-antithrombin or the thrombin-antithrombin interaction versus the level of added mucopolysaccharide exhibit an ascending limb, pseudoplateau, descending limb, and final plateau regions. In each case, the ascending limb and pseudoplateau are closely correlated with the concentration of heparin c antithrombin complex formed within the reaction mixture. Furthermore, the descending limb and final plateau of these two processes coincide with the generation of increasing amounts of the respective mucopolysaccharide-enzyme interaction products. The second-order rate constants for the neutralization of factor IXa or thrombin by the heparin . antithrombin complex are 3.0 x 10(8) M-1 min-1 and 1.7 x 10(9) M-1 min-1, respectively. The second-order rate constants for the inhibition of mucopolysaccharide-factor IXa or mucopolysaccharide-thrombin interaction products by the heparin . antithrombin complex are 2.0 x 10(7) M-1 min-1 and 3.0 x 10(8) M-1 min-1, respectively. These kinetic parameters must be contrasted with similarly designated constants obtained in the absence of mucopolysaccharide which are 2.94 x 10(4) M-1 min-1 and 4.25 x 10(5) M-1 min-1, respectively. Thus, our data demonstrate that binding of heparin to antithrombin is required for the mucopolysaccharide-dependent enhancement in the rates of neutralization of thrombin, factor IXa, factor Xa, or plasmin by the protease inhibitor. Furthermore, a careful comparison of the various constants suggests that the direct interaction between heparin and antithrombin may be largely responsible for the kinetic effect of this mucopolysaccharide.
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PMID:The kinetics of hemostatic enzyme-antithrombin interactions in the presence of low molecular weight heparin. 644 46

Fibrinogen degradation products formed by the action of purified haemolymph and saliva of a Saturnidae caterpillar of the Lonomia genus were studies by immunoelectrophoresis and polyacrylamide/SDS gel electrophoresis. The pattern of degradation differ form the one described for plasmin, trypsin, brinase, and ochrase. The most striking difference being the rapid loss of the alpha chain in spite of the presence of the protease inhibitor aprotinin, and/or denaturalizing agents such as 8 M Urea and 2% SDS.
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PMID:Studies on the degradation of fibrinogen by proteolytic enzymes from the larvae of Lanomia achelous (Cramer). 645 70

Radiolabeled alpha 2-antiplasmin cleared slowly from the circulation of mice. Complex formation with either plasmin or trypsin resulted in a significant increase in the plasma elimination rate of the protease inhibitor. Approximately 20 min and 14 min were required for 50% of the injected alpha 2-antiplasmin-plasmin and alpha 2-antiplasmin-trypsin to clear from the circulation, respectively. Significant competition was observed when radiolabeled alpha 2-antiplasmin-plasmin was cleared in the presence of a large molar excess of unlabeled alpha 2-antiplasmin-plasmin. alpha 1-Antitrypsin-trypsin failed to complete with radiolabeled alpha 2-antiplasmin-plasmin even when present at 2000 fold molar excess. Organ distribution studies localized the major site of alpha 2-antiplasmin-plasmin clearance in the liver. Microscopic autoradiography data suggested that the cell responsible for the clearance pathway was the hepatocyte.
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PMID:A unique pathway for the plasma elimination of alpha 2-antiplasmin-protease complexes in mice. 675 81

Porcine tissue plasminogen activator has been purified from delipidized heart tissue by affinity adsorption to fibrin. A crude fraction is prepared from an acid tissue extract by precipitation with ammonium sulphate. The tissue activator of this fraction is isolated by adsorption on fibrin and elution with KSCN. The procedure also includes chromatography on arginine-Sepharose and two gel-filtration steps. The final product has a specific activity of 250 000 IU/mg (+/- 16 000) as compared to an international urokinase reference preparation. The yield calculated from the active ammonium sulphate precipitate is about 28%. An approx. 7 000-fold increase of specific activity is obtained, most of which is achieved in the fibrin step. The native tissue plasminogen activator consists of a single chain molecule with a molecular weight of 64 000 as measured by SDS-polyacrylamide gel electrophoresis. In a previous report, it was claimed that the activator is composed of two disulphide-connected polypeptide chains. These results were due to a preparation artefact, caused by proteolytic activity present in the tissue extracts. The introduction of the protease inhibitor aprotinin and 6-amino-hexanoic acid in the purification procedure has abolished the effect of the protease contaminant, leading to the production of a one-chain activator. Treatment with plasmin transforms the native, one-chain tissue activator into a variant composed of two chains of about equal size (Mr 32 000) connected by disulphide bonding. This modified activator is indistinguishable from the one obtained at insufficient protection against proteolytic enzymes. The cleavage by plasmin causes about an 8-fold increase of amidolytic activity as measured on H-D-Val-Gly-Arg-p-nitroanilide. The fibrinolytic activity as measured by clot lysis in only slightly increased. The physiological significance of the cleavage is discussed.
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PMID:Purification and identification of two structural variants of porcine tissue plasminogen activator by affinity adsorption on fibrin. 689 Dec 67


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