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)

Pseudomonas aeruginosa alkaline proteinase, which is a zinc-dependent bacterial endopeptidase, preferentially hydrolyzed Boc-Val-Leu-Lys-methylcoumarylamide (MCA) which was originally designed as a specific substrate of plasmin, a plasma serine proteinase. The hydrolytic capacity was resistant to tosyl-lysine chloromethylketone at a concentration as high as 1 mM, but was blocked by a treatment with metal chelator such as o-phenanthroline at the concentration of 5 mM. Kinetic parameters of the amidolytic reaction were Km = 21 microM, kcat = 0.067 s-1 and kcat/Km = 3190 M-1 s-1. A synthetic peptide inhibitor which bore a possible ligand for zinc atom at the carboxy terminal was designed. This inhibitor, Ac-Val-Leu-Lys-4-mercaptoanilide, blocked the amidolytic activity of the pseudomonal alkaline proteinase in a competitive manner with the dissociation constant (Ki) value of 24 microM. The results imply that P. aeruginosa alkaline proteinase must be an unusual zinc-dependent 'C (COOH)-type' endopeptidase, which hydrolyzes the peptide bond of certain amino acid residues at the carboxyl group side by specific recognition, like serine- and cysteine-proteinases. In comparison, P. aeruginosa elastase which is a typical 'N (NH2)-type' metalloproteinase did not hydrolyze all of the commercially available peptide-MCA substrates tested at the present study. P. aeruginosa alkaline proteinase also hydrolyzed natural substrates of plasmin, such as fibrin and fibrinogen, with similar specific activities to plasmin. The susceptible subunits of fibrinogen were the A-alpha and B-beta ones, in this order. P. aeruginosa alkaline proteinase also exhibited an anti-coagulant activity in human plasma attributed to the direct fibrinogenolytic function. Such potential anti-coagulant capacity of the P. aeruginosa alkaline proteinase might explain, at least partly, the most characteristic pathologic feature of the P. aeruginosa septicemia, hemorrhagic lesions with lacking thrombi (Fetzer, A.E. et al. (1967) Am. Rev. Respirat. Dis. 96, 1121-1130).
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PMID:Pseudomonas aeruginosa alkaline proteinase might share a biological function with plasmin. 182 96

Glu-plasminogen interaction with fibrinogen fragment E results in the alteration of its adsorptive capacity. During this interaction in the absence of plasmin and tissue activator of plasminogen, Glu-plasminogen is transformed into a partly degraded form. Glu-plasminogen complexes with soluble and immobilized fibrinogen fragment E. contain a serine proteinase-specific activity which is inhibited by diisopropylfluorophosphate. The complexes under study are active towards fibrin and the plasmin-specific tripeptide substrate, D-Val-L-Leu-L-Lys-p-nitroanilide. It is concluded that fibrinogen fragment E induces structural changes in the enzyme molecule which eventually result in the formation of an active center.
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PMID:[Proteolytic activity of the Glu-plasminogen complex with fibrinogen fragment E]. 188 6

Serpins form a family of structurally related proteins, many of which function in plasma as inhibitors of serine proteases involved in inflammation, blood coagulation, fibrinolysis, and complement activation. To further characterize the mechanism by which serpins inhibit their target enzymes, we have studied the effect of temperature on the reaction of C1 inhibitor and the serine protease plasma kallikrein. At both 38 and 4 degrees C, C1 inhibitor (Mr 105,000) is cleaved by alpha-kallikrein (Mr 85,000 and 88,000) at position P1 (Arg444) of the reactive center, a reaction that leads to the formation of a covalent bimolecular enzyme-serpin complex (Mr 195,000) and cleaved but uncomplexed serpin (Mr 95,000). Between 38 and 4 degrees C, the product distribution is temperature-dependent, with more cleaved C1 inhibitor (Mr 95,000) formed at lower temperatures and correspondingly less Mr 195,000 complex. Studies employing intrinsic tryptophan fluorescence and 1H NMR spectroscopy show that this behavior is not caused by temperature-dependent conformational changes of kallikrein or C1 inhibitor. C1 inhibitor also behaves in this manner with the light chain of kallikrein and, to a lesser extent, with plasmin and C1s. These data are best explained by a branched reaction pathway, identical with the scheme describing the mechanism of action of suicide substrates. This scheme involves the formation of an enzyme-inhibitor intermediate, which can be stabilized into a covalent complex and/or dissociate into free enzyme and cleaved inhibitor, depending on the reaction conditions.
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PMID:Mechanism of serpin action: evidence that C1 inhibitor functions as a suicide substrate. 188 45

Plasminogen activators are serine proteinases which transform the serum zymogen, plasminogen, into plasmin, a broad-spectrum protease with fibrinolytic effect. Two main plasminogen activators have been described in humans: urokinase (UK; molecular weight, 55,000) and tissue-type plasminogen activator (tPA; molecular weight, 74,000). Thirteen subjects were studied who had alopecia areata (AA), nine in the active phase and four in remission. There were alterations in the perivascular and peribulbar fibrinolytic activity in the nine subjects in the active phase of disease, suggesting a possible role of plasminogen activators in AA. A modified Todd's autohistographic method was used to evaluate cutaneous fibrinolytic activity (which depended on the activity of plasminogen activators) in the 13 AA subjects and five volunteer controls. Cutaneous fibrinolytic activity was reduced in perivascular areas, but increased in peribulbar areas, in the nine subjects in the active phase of disease. Tests with monoclonal antibodies directed against the catalytic sites of tPA and UK showed that the perivascular fibrinolytic activity was tPA dependent, and the peribulbar fibrinolytic activity was UK dependent.
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PMID:The role of plasminogen activators in alopecia areata. 189 52

The major toxic and fibrinolytic activity of the saliva and hemolymph of the larval form of Lonomia achelous was purified to homogeneity by a combination of metal chelate and affinity chromatography. Two apparent isozymes, Achelase I (213 amino acids, pIcalc = 10.55) and Achelase II (214 amino acids, pIcalc = 8.51), were sequenced by automated Edman degradation, and their C-termini confirmed by Fourier-transform mass spectrometry. The calculated molecular weights (22,473 and 22,727) correspond well to Mr estimates of 24,000 by SDS-PAGE. No carbohydrate was detected during sequencing. The enzymes degraded all three chains of fibrin, alpha greater than beta much greater than gamma, yielding a fragmentation pattern indistinguishable from that produced by trypsin. Chromogenic peptides S-2222 (Factor Xa and trypsin), S-2251 (plasmin), S-2302 (kallikrein) and S-2444 (urokinase) were substrates while S-2288 (broad range of serine proteinases including thrombin) was not hydrolyzed. Among a range of inhibitors Hg+2, aminophenylmercuriacetate, leupeptin, antipain and E-64 but not N-ethylmaleimide or iodoacetate abolished the activity of the purified isozymes against S-2444. Phenylmethylsulfonyl fluoride, soybean trypsin inhibitor and aprotinin were less effective. The presence of the classic catalytic triad (histidine-41, aspartate-86 and serine-189) suggests that Achelases I and II may be serine proteinases, but with a potentially free cysteine-185 which could react with thiol proteinase-directed reagents.
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PMID:Isolation and complete amino acid sequence of two fibrinolytic proteinases from the toxic Saturnid caterpillar Lonomia achelous. 191 44

The authors report on the influence of plasminogen activators (PA) on implantation of TA3Ha mammary tumor cells in the healing hepatic wounds of syngeneic strain A mice. Intravenously injected TA3Ha cells, although they rarely metastasize to the liver, formed tumors in the hepatic wounds of a significant percent (42%, P less than 0.0001) of mice. The frequency of tumor formation declined as the interval between surgery and tumor cell inoculation was increased. Furthermore, preexposure of cells to fibrinogen, fibronectin, laminin, or peptides containing the arginine-glycine-aspartic acid-serine residues dramatically reduced the frequency of tumor formation in the hepatic wounds. These results indicate that TA3Ha cells interact with fibrinogen-related proteins in the wound to aid their attachment and growth. Because these proteins are susceptible to digestion by plasmin, PA were used in this study to examine whether administration of these drugs to the mice would modulate tumor formation in the liver wounds. Among the PA tested, human plasmin B-chain-streptokinase complex (B-SK) and recombinant tissue plasminogen activator (t-PA) inhibited tumor implantation in a dose-related manner. Administration of 900 units (U) of B-SK or 3300 U of t-PA per mouse reduced the frequency of tumor formation from 42% to 0% (P = 0.02) and 11% (P = 0.02), respectively. The B-SK was complexed with p-nitrophenyl-p-guanidinobenzoate; it did not activate the plasminogen or inhibit tumor formation in the hepatic wounds. Although urokinase activated the plasminogen, it did not inhibit tumor implantation in the hepatic wound. Heparin, an anticoagulant that prevents conversion of fibrinogen to fibrin without being fibrinolytic, had no influence on tumor formation in the hepatic wounds. The PA can generate plasmin that digests the cell attachment proteins in wounds and consequently inhibits tumor cell attachment.
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PMID:Inhibition of tumor implantation at sites of trauma by plasminogen activators. 191 15

A strong fibrinolytic enzyme was readily obtained in saline extracts of the earthworm, Lumbricus rubellus. It hydrolyzed not only plasminogen-rich fibrin plates, but also plasminogen-free fibrin plates. The average fibrinolytic activity was about 100 CU (plasmin units) or 250 IU (urokinase units)/g wet weight. The molecular weight and isoelectric point were about 20,000 and 3.4, respectively. The enzyme was heat-stable and displayed a very broad optimal pH range. DFP and SBTI strongly inhibited the enzyme, but the anti-plasmin agent, t-AMCHA, exerted little effect under the same conditions. Purification of the enzyme was performed and three partially purified fractions were obtained. These three fractions were further subdivided. The first fraction (F-I) was divided into three fractions (F-I-0, F-I-1, and F-I-2), which exhibited similar biochemical characteristics. The second fraction (F-II) could not be subdivided. The third fraction (F-III) was divided into two fractions (F-III-1 and F-III-2). Based on results for their enzymatic activities against various substrates, the fraction I enzymes are thought to represent a chymotrypsin-like enzyme and the fraction III enzymes to represent a trypsin-like enzyme. The fraction II enzyme appears to be neither a trypsin- or chymotrypsin-like enzyme nor an elastase. The amino acid compositions of the six enzymes were estimated. Compared with other serine enzymes, these enzymes contained very abundant asparagine or aspartic acid, and there was very little proline or lysine. From the above data, these enzymes are regarded as novel fibrinolytic enzymes, and we name them collectively as Lumbrokinase from the generic name of the earthworm.
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PMID:A novel fibrinolytic enzyme extracted from the earthworm, Lumbricus rubellus. 196 Aug 90

Cultures of transformed fibroblasts actively involved in extracellular matrix degradation have been examined for initial activation of serine and metallo protease cascade systems. Rous sarcoma virus transformed chick embryo fibroblasts (RSVCEF), in contrast to transformed mammalian cells, produce active, two chain urokinase-type plasminogen activator (tcu-PA). Active tcu-PA is found in serum-free, plasmin-free conditioned medium from RSVCEF cultures as determined by two independent methods, immunoprecipitation and differential DFP sensitivity. RSVCEF cultures synthesize and secrete inactive, single chain uPA (scu-PA) which is converted to tcu-PA in a time dependent manner by a catalytic mechanism that appears to involve a functioning uPA receptor on the surface of intact cells. The enzyme activity responsible for this conversion may represent the initiating catalytic event in the PA/plasminogen serine protease cascade system. A 70 kDa prometalloprotease capable of degrading denatured collagen following its activation also is significantly elevated in RSVCEF cultures over that of normal CEF. Trace amounts of the active 62 kDa form of the metalloprotease (gelatinase) is found in the transformed RSVCEF cultures indicating that these cultures produce a natural activator of the prometalloprotease. Plasmin and/or PA do not appear to be the activator of this enzyme as determined by indirect inhibition assays and direct assays employing purified enzymes. The possible central position of pro PA and the 70 kDa prometalloprotease in an interacting, complex protease cascade system involved in extracellular matrix degradation is discussed.
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PMID:Serine protease and metallo protease cascade systems involved in pericellular proteolysis. 196 54

Interleukin-1 (IL-1) release from monocyte-macrophages (Mo) appears dependent on pericellular proteolysis mediated by plasmin. Thus plasminogen activator inhibitors (PAI) which bind the serine proteases responsible for the conversion of plasminogen to plasmin, may inhibit IL-1 release from Mo. We have examined the effect of purified PAI from a hepatoma cell line Hep G2, on IL-1 release from Mo with secondary effects on lymphocyte proliferation in vitro. Fast acting inhibitors of both urokinase (u-PA) and tissue plasminogen activator (two chain t-PA) were noted in harvest fluids of Hep G2 cells. These inhibitors were stable at pH 3 but lost activity at 45 degrees C. They were SDS-stable and migrated with Mr53 and 104 kDa. These properties conformed to characteristics of type-1 plasminogen activator inhibitor (PAI-1). Partially purified PAI-1 added to human Mo cultured on 125I fibrin layer both in the presence and absence of plasminogen inhibited secretion of IL-1 by Mo in response to LPS. This effect, however, did not correlate with the inhibition of plasminogen dependent fibrinolysis. This suggested a degree of sequestration and inaccessibility of membrane bound u-PA of LPS activated Mo to PAI-1. PAI-1, in addition, inhibited mitogen stimulated peripheral blood mononuclear cell (PBMC) proliferation at similar concentration ranges. This effect was abrogated by the addition of specific antisera to PAI-1. PAI-1 may be released as part of an acute phase response. In addition to influencing fibrinolysis, PAI-1 may constitute a negative feedback pathway on Mo IL-1 release and subsequent immune activation in vivo.
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PMID:Monocyte-macrophage release of IL-1 is inhibited by type-1 plasminogen activator inhibitors. 196 70

Most of the organic, extracellular matrix of articular cartilage consists of collagens and proteoglycans. Their degradation is initiated extra- or peri-cellularly by proteinases produced locally by cells in and around the joint. Although enzymes from all four classes of proteinases can degrade the cartilagenous matrix, serine proteinases, particularly plasmin, and various neutral metalloproteinases (NMPs) are likely to be the key enzymes in this process. Much attention has been paid to members of the latter group, which are synthesised both by the resident, mesenchymal cells of the joint and by various types of white blood cells which colonise it during inflammation. NMPs can be conveniently grouped into three classes, the collagenases, the stromelysins and the gelatinases. Two members are known for each class, with the recently identified "pump" (Putative Metalloproteinase) probably constituting a third member of the stromelysin group. Regulation of these enzymes is complex. Cells normally synthesise NMPs at low rates, but their production increases markedly following cellular activation by cytokines or certain other stimuli. Major control points for enzyme synthesis occur at the levels of transcription and the conversion of proenzyme to active enzyme; enzyme activity is further regulated through the action of inhibitors. Alpha-2 macroglobulin is the major systemic inhibitor, while a number of tissue inhibitors act as local regulators. These include at least two TIMPs and several IMPs. Pharmacologic manipulation of NMP activity holds promise as an approach to anti-erosive therapy in arthritis.
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PMID:The role of proteinases in cartilage destruction. 206 82


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