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)

Complement components are activated by immunologic and non-immunologic mechanisms through various plasma protein systems such as immunoglobulins, properdin, plasmin, thrombin and Hageman factor. The activation of Hageman factor, followed by complement cleavage leading to liberation of various chemical mediators, can be initiated by exposure of negatively charged tissue components due to trauma and infection.
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PMID:Hageman complement and factor. 84 8

A highly purified preparation of human properdin (P) has been obtained in a simple two-step procedure utilizing reversed application of the technique of affinity chromatography. The method involved precipitation of properdin from human serum and subsequent passage through an immunoadsorbent column of Sepharose anti-RP globulin which bound the contaminating proteins. The immunochemical properties of the isolated properdin (P) was found to be different from those of activated properdin (P). P was shown to be a 6.1S, beta2 globulin with a mean subunit m.w. of 57,900. P on the other hand was a 5.1S protein with gamma2 mobility and a subunit m.w. of 53,000 daltons. Double diffusion analysis using anti-P revealed a reaction of identity between P and P. However, when the reaction was developed with anti-P, a reaction of partial identity was obtained and the precipitin line of P was seen to spur over the line developed with P. Mild treatment with plasmin or trypsin converted P to P. Unlike P, P was ineffective in triggering the activation of the Properdin System in RP unless trace amounts of zymosan were added. Under these conditions P was found to be converted to P. The results indicate that properdin is present in fresh serum in a precursor form and its activation to P involves a limited proteolytic cleavage of the molecule.
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PMID:Purification of native properdin by reversed affinity chromatography and its activation by proteolytic enzymes. 95 Apr 61

Isolated inherited deficiency states of almost every complement protein have been recognized. Almost all are autosomal recessive traits. Deficiency of the early-acting components C1, C4 and C2 is associated with increased risk of immune complex disease, particularly systemic lupus erythematosus. Patients with deficiency of C3, factor I or factor H have increased susceptibility to infection by pyogenic bacteria, whereas those with deficiencies of properdin, C5, C6, C7 or C8 are prone to systemic neisserial infection. Inherited deficiency of C1 inhibitor is transmitted as an autosomal dominant trait, is genetically heterogeneous, and is associated with attacks of angioedema and consumption of C4 and C2. There is evidence that a plasmin-modified fragment of C2 is responsible for the angioedema in this disorder. Administration of androgens tends to correct the biochemical abnormalities of hereditary angioedema and to prevent attacks.
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PMID:Inherited deficiencies of complement components in man. 357 Mar 60

Activation of the classical complement pathway is initiated by immune complexes consisting of IgM antibody or IgG subclasses 1, 2, and 3. Binding to Clq leads to activation of C1s and digestion of C4 and C2 to yield a C3 convertase. The alternative complement pathway is initiated by complex polysaccharides as well as immune complexes of the IgA class which interact with Factors B, D, C3, and properdin to yield a stabilized C3 convertase consisting of PC3Bb. Cleavage of C3 and C5 by either pathway yields the C3a and C5a anaphylatoxins which cause histamine release from mast cells and formation of the C5b6789 attack complex causes cell lysis. Both immunologic and nonimmunologic tissue damage can initiate the surface dependent pathways of coagulation, fibrinolysis, and kinin formation. Surface bound Hageman Factor interacts with complexes of prekallikrein and HMW-kininogen as well as Factor XI and HMW-kininogen to form activated Hageman factor, kallikrein, and Factor XIa. Factor XIa continues the coagulation pathway, kallikrein and Factor XIa convert plasminogen to plasmin and kallikrein digests HMW-kininogen to yield bradykinin. The Cl inhibitor, which inactivates Cls is the major plasma inhibitor of activated Hageman factor and kallikrein. In its absence, a potentially fatal form of angioedema is seen. The inactivator of the C3a and C5a anaphylatoxins is identical to carboxypeptidase N, the major plasma inactivator of bradykinin thus demonstrating the common control mechanisms which regulate the complement and kinin-forming pathways.
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PMID:The intrinsic coagulation-kinin pathway, complement cascades, plasma renin-angiotensin system, and their interrelationships. 704 77

Many properties have been assigned to the procollagen and properdin (Type I) modules of thrombospondin-1 (TSP1) based on activities of large proteolytic fragments of TSP1 or peptides containing TSP1-derived sequences. To examine the activities of the modules more exactly, we expressed the first properdin module (P1); the third properdin module (P3); the first and second properdin modules (P12); the first, second, and third properdin modules (P123); and the procollagen module with the first, second, and third properdin modules (CP123) in the GELEX expression vector (GE1) using the baculovirus system. GE1 encodes the pre-pro sequence, the transglutaminase cross-linking site(s), the protease-sensitive site, and the gelatin binding domain from the amino terminus of rat fibronectin. All five recombinant proteins were expressed by insect cells, secreted into the culture medium, and purified by gelatin-agarose affinity chromatography. P123 shared with TSP1 a resistance to trypsin unless reduced and alkylated. P12/GE1, P123/GE1, and CP123/GE1 bound poorly to heparin-agarose except in the absence of sodium chloride, whereas peptides based on P2 are known to bind to heparin in up to 150 mM sodium chloride. In cross-linking experiments employing activated recombinant factor XIII and the transglutaminase cross-linking site in the fibronectin-derived sequence, P12/GE1, P123/GE1, CP123/GE1, and P3/GE1 but not P1/GE1 became incorporated into a fibrin clot more than GE1 alone. Analysis of the complex indicated that cross-linking was to the portion of the fibrin alpha-chain remaining in the D-dimer of plasmin digests. P123 also cross-linked to the Aalpha-chain of unclotted fibrinogen. P123 competed for 125I-TSP1 incorporation into the fibrin clot. P123 did not cross-link to plasminogen, histidine-rich glycoprotein, fibronectin, or plasma globulins other than fibrinogen/fibrin. These results indicate that the properdin modules of TSP1 specifically interact with fibrinogen/fibrin but not with heparin under physiologic conditions.
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PMID:Interaction of recombinant procollagen and properdin modules of thrombospondin-1 with heparin and fibrinogen/fibrin. 986 61