Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.4.21.7 (plasmin)
 9,023 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We have previously established that the mitogenic effect of fibrinogen on hemopoietic cell lines Raji and JM is mediated via a specific receptor (Levesque, J.-P. et al.: Proc. Natl. Acad. Sci. USA 83:6494-6498, 1986). In this study, we have further characterized the fibrinogen domain involved in the binding to the mitogenic receptor. This binding was not inhibited either by a monoclonal antibody against the C-terminal sequence of the fibrinogen gamma chains or by synthetic peptides containing the Arg-Gly-Asp sequence. Such inhibition is specific of the platelet fibrinogen receptor, the glycoprotein IIb-IIIa complex. Fragments containing the fibrinogen D domain were the only plasmin degradation products of fibrinogen which were mitogenic. These fragments acted via direct binding on the mitogenic receptor with a Kd of 2.24 X 10(-6) M. This value was similar to the KI value of unlabeled fragments D (2.47 X 10(-6) M). Our results suggest the presence of two different functional types of fibrinogen receptors: the glycoprotein IIb-IIIa receptor responsible both for platelet aggregation and leukocyte adhesion and killing, and the mitogenic receptor involved in proliferation control of hemopoietic cells.
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PMID:Evidence for two functionally different fibrinogen receptors on hemopoietic cells: the glycoprotein IIb-IIIa and the mitogenic fibrinogen receptor. 362 17

Single-chain urokinase (SC-UK) has an intrinsic amidolytic activity, as measured with synthetic substrate (Kabi S-2444; pyro-Glu-Gly-Arg-pNitroanalide), which was found to be 0.1% to 0.2% that of its plasmin-activated derivative, two-chain UK (TC-UK). A study of the reaction of SC-UK with plasminogen is complicated by the effect of the reaction product, plasmin, on both reactants. The resultant generation of TC-UK and Lys-plasminogen produces secondary reactions which greatly augment plasminogen activation. To confine enzymatic activity to the primary reaction, after pretreatment to eliminate trace TC-UK contaminants, SC-UK was incubated with Glu- or Lys-plasminogen in the presence of aprotinin (500 KIU/mL) to inhibit generated plasmin and dansyl-glutamyl-glycyl-arginyl-chloromethylketone (20 mumol/L), which irreversibly inhibited TC-UK but not SC-UK. Analysis by reducing sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) showed a plasminogen-activating activity for SC-UK that was approximately 0.4% that of TC-UK. Both SC-UK and TC-UK preferentially activated Lys-plasminogen over Glu-plasminogen. Similarly, Glu-plasminogen activation was augmented by lysine or soluble fibrin. The ratio of the reaction rates of SC-UK and TC-UK were comparable for Glu- and Lys-plasminogen. It is concluded that there is a major difference in the catalytic activities of SC-UK and TC-UK against plasminogen that is comparable to that against synthetic substrate.
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PMID:Activation of plasminogen by single-chain urokinase or by two-chain urokinase--a demonstration that single-chain urokinase has a low catalytic activity (pro-urokinase). 379 Jul 24

We have studied the susceptibility of fibrils formed from fetal bovine skin type III collagen to proteolytic enzymes known to cleave within the helical portion of the molecule (vertebrate and microbial collagenase, polymorphonuclear elastase, trypsin, thermolysin) and to two general proteases of broad specificity (plasmin, Pronase). Fibrils reconstituted from neutral salt solutions, at 35 degrees C, were highly resistant to nonspecific proteolysis by general proteases such as polymorphonuclear elastase, trypsin, and thermolysin but were rapidly dissolved by bacterial and vertebrate collagenases at rates of 12-45 mol X mol-1 X h-1. In solution, type III collagen was readily cleaved by each of the proteases (with the exception of plasmin), as well as by the true collagenases, although at different rates. Turnover numbers determined by viscometry at 35 degrees C were: human collagenase, approximately equal to 1500 h-1; microbial (clostridial) collagenase, approximately equal to 100 h-1; and general proteases, 23-52 h-1. In addition it was shown that pronase cleaves type III collagen in solution at 22 degrees C by attacking the same Arg-Gly bond in the alpha 1(III) chain as trypsin. However, like other proteases, Pronase was rather ineffective against fibrillar forms of type III collagen. It was also shown that transition of type III collagen as well as type I collagen to the fibrillar form resulted in a significant gain of triple helical thermostability as evidenced by a 6.8 degrees C increase in denaturation temperature (Tm = 40.2 degrees C in solution; Tm = 47.0 degrees C in fibrils).
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PMID:Cleavage of bovine skin type III collagen by proteolytic enzymes. Relative resistance of the fibrillar form. 390 16

A case of inherited bisalbuminemia was discovered in which electrophoretic controls showed that the proportion of the abnormal albumin decreased progressively during storage of the serum either at 4 degrees C or at room temperature. Such a decrease was also found when the serum was incubated with the proteolytic enzymes trypsin or plasmin. Studies with the isolated abnormal albumin showed that either during storage or after incubation with trypsin (or plasmin), its mobility became identical to that of normal serum albumin. Structural analyses showed that the albumin variant was identical to the previously described pro-albumin Christchurch that contains an additional N-terminal sequence: Arg-Gly-Val-Phe-Arg-Gln. It was therefore suggested that the progressive decrease of the abnormal albumin during storage by serum was related to the cleavage of the N-terminal abnormal sequence by plasmin already present in the serum. The decrease of the abnormal albumin during storage was inhibited by addition of cortisol to serum (1 mol per mol serum albumin). This was found related to a protective effect of cortisol bound to the albumin variant on proteolysis by plasmin.
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PMID:Studies of an abnormal serum albumin unstable upon storage. 621 90

The aim of the present study is to elucidate the enzymological and chemical properties of the plasminogen activator in bile, bilokinase. A bilokinase preparation was obtained from 94.2 liters of bovine gall bladder bile through seven purification steps, two of which employed a precipitation method in which ammonium sulfate and acetone were used sequentially. Twenty mg of bilokinase preparation with a specific activity of 5,900 IU/mg were obtained, for a 9% yield with 6,556-fold purification. This preparation revealed a single band upon disc electrophoresis. The bilokinase was a 3.32 S protein and its molecular weight was found to be 57,000. Isoelectric focusing showed that the bilokinase was separable into 5 fractions having different isoelectric points ranging from pH 7.4 to 9.0 The properties of the individual fractions have not yet been determined. The enzymatic activity of bilokinase was recognized to be heat-labile and to be stable at pH 4.0. The activation of plasminogen by bilokinase took place most effectively at pH 7.8 in a manner similar to that of urokinase. In its hydrolysis of both N alpha-acetylglycyl-L-lysine-methyl ester-acetate and H-D-Glu-Gly-Arg-pNA (S-2227), bilokinase showed similar Km values to those of urokinase; however, they were quite distinct from those of plasmin. It was concluded therefore that bilokinase is a plasminogen activator with enzymatic properties which are quite similar to those of the urinary plasminogen activator urokinase. The origin of bilokinase and its relation to liver function are now under investigation.
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PMID:Purification and characterization of the biliary plasminogen activator bilokinase. 621 7

In a 81 year old health woman, gross abnormalities of fibrin formation led to the discovery of an abnormal fibrinogen named fibrinogen Bondy. Clottability of purified fibrinogen Bondy was only 53% compared to 95-98% for normal fibrinogen. Functional studies revealed (i) delayed coagulation by thrombin and batroxobin (Reptilase), (ii) incomplete release of fibrino-peptides A and B, (iii) poor fibrin monomer aggregation, (iv) delayed fibrin proteolysis by plasmin. Electrophoretic mobility of fibrinogen Bondy, its three chains and the products of fibrin cross-linking, was normal. Fibrinogen NH2-terminal residues of fibrinogen Bondy were found to be normal. The presence of Ala, in addition to Gly and Tyr in the fibrin clot and its supernatant, showed that a part of fibrinogen molecules was not clotted, i.e. either copolymerised with fibrin or remaining in solutions. Gel filtration of the supernatant allowed the separation of both soluble complexes and fibrinogen. This fibrinogen population was shown to be unclottable by thrombin and to inhibit clotting of normal fibrinogen.
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PMID:Fibrinogen Bondy: a new case of dysfibrinogenemia. Isolation of the abnormal fibrinogen molecules. 621 86

A fluorogenic substrate for plasmin, CBZ-Gly-Pro-Arg-AEC, has been synthesized and used to develop a new sensitive photometric and fluorometric assay of plasminogen activator activity. The fluorescence intensity of free AEC at 460 nm is about 3 orders of magnitude higher than that of acyl-AEC. The release of AEC from the peptidyl derivative was monitored fluorometrically after extraction of free AEC in ethylacetate. Under such conditions, the Km was 0.16 mM. This method was used to monitor the activity of plasminogen activator synthetized by fibroblastic cells (BHK 21 C 13) either released in the supernatants or cell-associated.
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PMID:Sensitive fluorometric determination of plasminogen activator in cell lysates and supernatants. 622 16

It was found that the effect of heparin on the amidase activity of urokinase (E C 3.4.21.31), plasmin (E C 3.4.21.7) and trypsin (E C 3.4.21.4) depended on the substrate used. No effect of heparin on the amidase activity of urokinase and trypsin was observed when Pyro Glu-Gly-Arg-p-nitroanilide (S-2444) and alpha-N-acetyl-L-lysine-p-nitroanilide (ALNA) were used as substrates. Heparin acted as a uncompetitive inhibitor of trypsin (Ki = 1.2 X 10(-6) M), plasmin (Ki = 4.9 X 10(-6) M) and urokinase (Ki = 1.0 X 10(-7) M) when Bz-Phe-Val-Arg-p-nitroanilide (S-2160), H-D-Val-Leu-Lys-p-nitroanilide (S-2251) and plasminogen, respectively, were used as substrates. These results, as well as the data obtained by studying the effect of the simultaneous presence of heparin and competitive inhibitors suggest that although heparin is not bound at the active center of these enzymes, it may influence the effectivity of catalysis.
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PMID:Kinetic study of the effect of heparin on the amidase activity of trypsin, plasmin and urokinase. 622 10

A series of dipeptide derivatives of Rhodamine, each containing an arginine residue in the P1 position and one of ten representative benzyloxycarbonyl (Cbz)-blocked amino acids in the P2 position, has been synthesized, purified and characterized as substrates for serine proteinases. These substrates are easily prepared with high yields. Cleavage of a single amide bond converts the non-fluorescent bisamide substrate into a highly fluorescent monoamide product. Macroscopic kinetic constants for the interaction of these substrates with bovine trypsin, human and dog plasmin, and human thrombin are reported. Certain of these substrates exhibit extremely large specificity constants. For example, the kcat./Km for bovine trypsin with bis-(N-benzyloxycarbonylglycyl-argininamido)-Rhodamine [(Cbz-Gly-Arg-NH)2-Rhodamine] is 1 670 000 M-1 X S-1. Certain of these substrates are also highly selective. For example, the most specific substrate for human plasmin, (Cbz-Phe-Arg-NH2)-Rhodamine, is not hydrolysed by human thrombin, and the most specific substrate for human thrombin, (Cbz-Pro-Arg-NH)2-Rhodamine, is one of the least specific substrates for human plasmin. Comparison of the kinetic constants for hydrolysis of the dipeptide substrates with that of the single amino acid derivative, (Cbz-Arg-NH)2-Rhodamine, indicates that selection of the proper amino acid residue in the P2 position can effect large increases in substrate specificity. This occurs primarily as a result of an increase in kcat. as opposed to a decrease in Km and, in certain cases, is accompanied by a large increase in selectivity. Because of their high degree of sensitivity and selectivity, these Rhodamine-based dipeptide compounds should be extremely useful substrates for studying serine proteinases.
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PMID:New class of sensitive and selective fluorogenic substrates for serine proteinases. Amino acid and dipeptide derivatives of rhodamine. 622 22

A proteinase which can activate human, dog and rat plasminogen to plasmin has been isolated from the urine of female rats, using affinity chromatography on benzamidine-coupled Sepharose. Inhibition by diisopropylfluorophosphate, tosyl-L-lysine chloromethylketone and benzamidine classified the enzyme as trypsin-like. The proteinase has weak activity on alpha-casein and hemoglobin, but will not lyse fibrin clots. It readily cleaves arginyl amides, including synthetic substrates specific for human glandular kallikrein and other serine proteinases. A chromogenic substrate for human urokinase (pyro Glu-Gly-Arg-pNA) is a poor substrate for the rat proteinase. Characteristics of the enzyme, such as its molecular weight (25 900), kinetic parameters and inhibition by aprotinin, indicate that this proteinase is esterase A, described by several investigators. Esterase A is shown not to be a true urinary plasminogen activator but rather is a unique arginine-specific proteinase. Urokinase-like and kallikrein-like activity are part of a broader proteolytic activity displayed by this enzyme.
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PMID:Esterase A is a proteinase from rat urine that can activate plasminogen. 623 43


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