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)

We studied the synthesis and secretion of alpha-2-macroglobulin by cultures of human adherent cells. Much more alpha-2-macroglobulin (measured by radioimmunoassay) accumulated in media of established strains of adherent cells derived from embryonic lung than in media of established strains derived from adult skin or rheumatoid synovium. Alpha-2-macroglobulin accumulated in media of primary cultures of adherent cells from a variety of embryonic tissues. However, the amount of alpha-2-macroglobulin accumulating in media of subsequent passage of these cells declined for all strains except those derived from lung. Immunodiffusion and double-antibody immunoprecipitation studies of cell extracts and media after incubation of cells with l-[(35)S]methionine supported the radioimmunoassay finding that adherent cells from lung synthesized and secreted more alpha-2-macroglobulin than adherent cells from skin. Intracellular alpha-2-macroglobulin could not be detected by radio-immunoassay or visualized by immunofluorescent microscopy, suggesting that synthesized alpha-2-macroglobulin is rapidly secreted. Plasminogen-rich fibrin clots were lysed in culture media of adherent cells from embryonic lung and, to a lesser extent, heart. Adherent cells from other tissues, which produced less alpha-2-macroglobulin, did not lyse fibrin clots. However, all cultures of adherent cells contained pericellular fibronectin, a large, external, transformation-sensitive glycoprotein known to be cleaved by plasmin. We speculate that production of alpha-2-macroglobulin may be a means for protease-secreting normal cells to preserve cell surface integrity and that alpha-2-macroglobulin synthesized locally in lung may protect lung tissues from a variety of proteases.
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PMID:Synthesis and secretion of alpha-2-macroglobulin by cultured adherent lung cells. Comparison with cell strains derived from other tissues. 7 7

Factor VIII/von Willebrand factor (FVIII/vWF) is a glycoprotein with a molecular weight greater than one-million daltons. Two activities are associated with this large molecule: FVIII procoagulant activity and vWF activity. Incubation of FVIII/vWF with proteolytic enzymes causes rapid inactivation of the FVIII procoagulant activity but has little effect on the vWF activity or antigenicity. In an attempt to gain insight into the structural features required for these two activities, antisera were raised in rabbits to normal, thrombin-inactivated, and plasmin-inactivated FVIII/vWF. All of these proteolytically modified forms of FVIII/vWF cross-reacted with each of the rabbit antisera; each blocked the ability of a human inhibitor to inactivate native active FVIII/vWF. Each of the antisera was a potent inhibitor of vWF activity and inactivated vWF activity at the same titer. The antisera were much less potent inhibitors of FVIII activity than of vWF activity. Antibodies to thrombin-inactivated FVIII/vWF or normal FVIII/vWF had about the same ability to inactivate FVIII procoagulant activity. Surprisingly, those to plasmin-inactivated FVIII/vWF still retained about 50% of this inhibitory capacity. A comparison of the three types of antigens by polyacrylamide gel electrophoresis in sodium dodecyl sulfate-6 M urea demonstrated that the structure of thrombin-inactivated FVIII/vWF was indistinguishable from that of normal FVIII/vWF, while plasmin-inactivated FVII/vWF was completely cleaved to lower molecular weight fragments. Some of the reported variations in the ability of rabbit antibodies to inhibit procoagulant activity may be due to partial degradation of the starting antigen. The retention by FVIII/vWF protein of its immunologic properties even after extensive proteolytic degradation suggests that under nondenaturing conditions, the conformation of the native and degraded molecules are very similar.
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PMID:Immunologic studies of native and modified human factor VIII/von Willebrand factor. 8 37

Neither normal nor hemophilic factor VIII protein enters a 5% sosium dodecyl sulfate gel; on reduction, however, a single 195 000-molecular-weight peptide is observed. Hemophilic and normal factor VIII contain carbohydrate and appear identical in subunit molecular weight, electrical charge, and major antigenic determinants. Thrombin activation and inactivation of factor VIII does not detectably change the subunit molecular weight. Trypsin causes similar activity changes and obviously cleaves the factor VIII subunit. Human plasmin destroys factor VIII procoagulant activity and degrades the factor VIII subunit to 103 000-, 88 000-, and 17 000-molecular-weight peptides. Both normal and hemophilic factor VIII as well as thrombin-inactivated factor VIII support ristocetin-induced platelet aggregation. Purified factor VIII chromatographed on 4% agarose in 1.0 M sodium chloride shows no dissociation of the procoagulant activity from the void volume protein. Gel chromatography on 4% agarose in 0.25 M calcium chloride results in a procoagulant activity peak removed from the void volume protein; both peaks contain protein which does not enter a 5% SDS gel, but on reduction a 195 000-molecular-weight subunit band is observed for each. Both the void volume protein peak and the procoagulant activity peak from the 0.25 M calcium chloride-agarose gel column support ristocetin-induced platelet aggregation. After removal of calcium, a small amount of procoagulant activity is present only in the void volume peak. These data suggest that both the procoagulant and von Willebrand activities are on the same molecule. Thus our previous conclusion remains the same: human factor VIII is a large glycoprotein composed of identical 195 000-molecular-weight subunits jointed by disulfide bonds and is responsible for both antihemophilic and von Willebrand activities in human plasma.
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PMID:Molecular structural studies of human factor VIII. 12 89

A procedure is presented for purifying a novel proteinase inhibitor in human plasma whose apparent unique biological property is to inhibit efficiently the lysis of fibrin clots induced by plasminogen activator. The final product is homogeneous as judged by disc gel electrophoresis, and immunoelectrophoresis. Its molecular weight estimated by sodium dodecyl sulfate gel electrophoresis or sedimentation equilibrium is 67,000 and 63,000, respectively. The inhibitor is a glycoprotein consisting polypeptide chain containing 11.7% carbohyrate. It migrates in the alpha2-globulin region in immunoelectrophoresis. The inhibitor is chemically and immunologically different from all the other known inhibitors in plasma. Inhibition of plasmin by the inhibitor is almost instantaneous even at 0 degrees, in contrast to the slow inhibition of urokinase (plasminogen activator in urine). Plasminogen activation by urokinase-induced clot lysis is inhibited by the inhibitor mainly through a mechanism of instantaneous inhibition of plasmin formed and not through the inhibition of urokinase. The inhibitor also inhibits trypsin. Consequently, it is suggested that this newly identified inhibitor is named alpha2-plasmin inhibitor or alpha2-proteinase inhibitor. A specific antibody directed against the inhibitor neutralizes virtually all inhibitory activity of plasma to activator-induced clot lysis. Immunochemical quantitation of the inhibitor was specific antiserum to the inhibitor and the purified inhibitor as a standard indicates that the concentration of the inhibitory in the serum of a healthy man is in or near the range of 5 to 7 mg/100 ml, which is the lowest concentration among the concentration of the proteinase inhibitors in plasma. The inhibitor and plasmin, trypsin, or urokinase form a complex which cannot be dissociated with denaturing and reducing agents. The formation of the enzyme-inhibitor complex occurs on a 1:1 molar basis and is associated with the cleavage of a unique peptide bone, which is most clearly demonstrated in the interaction of the inhibitor and beta-trypsin. In the complex formation between the inhibitor and plasmin, the inhibitor is cross-linked with the light chain which contains the active site of plasmin. It is suggested that, in a fashion analogous to complex formation between alpha1-antitrypsin and trypsin, the cross-links are formed between the active site serine of the enzyme and the newly formed COOH-terminal residue of the inhibitor, with cleavage of a peptide bond.
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PMID:Isolation and characterization of alpha2-plasmin inhibitor from human plasma. A novel proteinase inhibitor which inhibits activator-induced clot lysis. 13 98

The fast-acting and physiologically most important inhibitor of plasmin in human plasma is a recently discovered and purified alpha 2-glycoprotein with a molecular weight of 65,000-70,000 daltons occurring at a concentration of 1 muM. The inhibitor rapidly forms a completely inactive 1:1 stoichometric complex with plasmin through reaction with the B chain (light chain) of the enzyme, which contains the active center. It also reacts with trypsin and very slowly with urokinase and with some other enzymes in purified systems, but its role in vivo as an inhibitor of proteases other than plasmin seems negligible. Antiplasmin is the only plasma protein that can inhibit the fibrinolysis associated with transformed or malignant cells. The plasmin-antiplasmin complex contains neoantigenic structures not present in the parent molecules that may form the basis of immunochemical methods for detecting activation of the fibrinolvtic system in blood.
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PMID:Fast-acting plasmin inhibitor in human plasma. 14 16

Bovine plasma CIg, like human CIg, is a glycoprotein with a molecular weight of approximately 450,000 daltons and consists of two homologous subunits, the alpha and beta chains. These subunits are covalently linked through disulfide bridges in their carboxyl terminal domains. The carboxyl terminal regions are presumed to contain the fibrin-reactive transamidation site. The covalent incorporation of CIg into fibrin has been conclusively demonstrated by isolation of the S-carboxymethyl derivative of the CIg-fibrin-alpha chain complex and by determination of its terminal amino acid sequences. Cold-insoluble globulin has been shown to exert a stimulatory effect on the urokinase-mediated activation of bovine plasminogen to plasmin.
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PMID:Bovine plasma cold-insoluble globulin: gross structure and function. 15 11

We have observed that treatment of rabbit synovial fibroblasts with proteolytic enzymes can induce secretion of collagenase (EC 3.4.24.7) and plasminogen activator (EC 3.4.21.-). Cells treated for 2-24 hr with plasmin, trypsin, chymotrypsin, pancreatic elastase, papain, bromelain, thermolysin, or alpha-protease but not with thrombin or neuraminidase secreted detectable amounts of collagenase within 16-48 hr. Treatment of fibroblasts with trypsin also induced secretion of plasminogen activator. Proteases initiated secretion of collagenase (up to 20 units per 10(6) cells per 24 hr) only when treatment produced decreased cell adhesion. Collagenase production did not depend on continued presence of proteolytic activity or on subsequent cell adhesion, spreading, or proliferation. Routine subculturing with crude trypsin also induced collagenase secretion by cells. Secretion of collagenase was prevented and normal spreading was obtained if the trypsinized cells were placed into medium containing fetal calf serum. Soybean trypsin inhibitor, alpha(1)-antitrypsin, bovine serum albumin, collagen, and fibronectin did not inhibit collagenase production. Although proteases that induced collagenase secretion also removed surface glycoprotein, the kinetics of induction of cell protease secretion were different from those for removal of fibronectin. Physiological inducers of secretion of collagenase and plasminogen activator by cells have not been identified. These results suggest that extracellular proteases in conjunction with plasma proteins may govern protease secretion by cells.
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PMID:Proteases induce secretion of collagenase and plasminogen activator by fibroblasts. 20 72

Pregnancy Associated Plasma Protein A (PAPP-A) has been isolated from late pregnancy plasma using ammonium sulphate precipitation, ion exchange chromatography, affinity chromatography on Concanavalin-A, gel filtration and negative affinity chromatography. It was found that PAPP-A is an alpha 2-glycoprotein of 750-820 000 MW, probably a dimer with each monomer being composed of 2 polypeptide chains of 218 000 MW. The amino acid composition as well as other physicochemical characteristics are similar to human alpha 2-macroglobulin. PAPP-A exhibits in vitro an inhibition of the activity of the complement system, of the caseinolytic activity of plasmin and possibly of the urokinase activation of plasminogen. The hypothesis that PAPP-A plays a role in the regulation of fibrinolysis during pregnancy is put forward.
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PMID:Purification and characterization of pregnancy associated plasma protein A (PAPP-A). 51 34

The isolation and characterization of placemental protein PP5 is described. The purification was achieved by use of immunoadsorbents. From the tissue of one human term placenta an average amount of 15 mg PP5 can be extracted. PP5 apparently is specific for the placenta; it could not be detected in extracts from other human tissues. In sera from pregnant women PP5 is not present or only in trace amounts (less than 0.1 mg%). In the ultracentrifuge PP5 was found to have a sedimentation coefficient of 2.8 S and a molecular weight of 36,600 daltons. Electrophoretically the protein migrates as a fast beta1-globulin. The isoelectric point was determined to be 4.6. PP5 is a glycoprotein and contains 19.8% carbohydrates (hexoses 10.0%, hexosamine 4.4%, fucose 0.4%, sialic acid 5.0%). The amino acid composition of the protein is reported, too. PP5 was found to inhibit the activity of trypsin and plasmin; the biological role of this protein therefore may be the inhibition of proteases.
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PMID:[Isolation and characterization of the placental protein pp5 (author's transl)]. 57 96

Factor XII was purified approximately 14 000-fold from bovine plasma by ammonium sulfate fractionation followed by heparin-agarose, DEAE-Sephadex, CM-cellulose, arginine-agarose, and benzamidine-agarose column chromatography. By this method, about 15 mg of protein was purified from 15 L of plasma with an overall yield of 18%. The purified protein was homogeneous as judged by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and amino-terminal analysis. Bovine factor XII is a glycoprotein with a mol wt of 74 000 as determined by sedimentation equilibrium centrifugation. It contains 13.5% carbohydrate including 3.4% hexose, 4.7% N-acetylhexosamine, and 5.4% N-acetylneuraminic acid. Factor XII is a single polypeptide chain with an NH2-terminal sequence of Thr-Pro-Pro-Trp-Lys-Gly-Pro-?-Lys-His. This sequence is homologous to the reactive-site regions of a number of protease inhibitors. The amino acid sequence of a carboxyl-terminal fragments prepared by cyanogen bromide digestion was found to be Leu-Cys-Ala-Gly-Phe-Leu-Glu-Gly-Gly-Thr-Asp-Ala-Cys-Gln-Gly-Asp-SER-Gly-Gly-Pro-Leu-Val-Cys-Glu-Asp-Glu. This sequence is homologous with the active site of a number of plasma serine proteases including thrombin, factor IXa, factor Xa, and plasmin. These data indicate that bovine factor XII is a precursor to a serine enzyme with an inhibitor sequence and a catalytic site located in the same single polypeptide chain.
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PMID:Isolation and characterization of bovine factor XII (Hageman factor). 86 Dec 10


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