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 peptide band of approximately 105 kDa migrating near the gamma dimer position of disulfide bond reduced human plasma fibrinogen prepared from fresh single donor or outdated plasma was identified by SDS-PAGE. The band, amounting to approximately 2% of the total A alpha/gamma chain population, was thrombin and plasmin sensitive and reacted with antibodies to A alpha or gamma chains but not with antibodies to B beta chains, plasminogen, or factor XIII. Amino acid sequencing revealed a double sequence corresponding to that of A alpha and gamma chains, indicating that the band consists of covalently cross-linked A alpha.gamma chain heterodimers. A alpha.gamma heterodimers were identified as a component of monomeric fibrinogen by two-dimensional SDS-PAGE and by SDS-PAGE analysis of the monomer fraction isolated by gel sieving chromatography, thus indicating that A alpha.gamma heterodimers arise by intramolecular A alpha/gamma chain cross-linking.
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PMID:Evidence of intramolecular cross-linked A alpha.gamma chain heterodimers in plasma fibrinogen. 863 42

Plasmin sensitive sites are found on the A alpha, B beta and gamma chains of fibrinogen at regions joining the two C-terminal D fragments with the central E fragment. We have developed a monoclonal antibody (MoAb) reactive with this plasmin sensitive region on the human fibrinogen gamma chain and mapped its epitope. MoAb J88B reacts with gamma chains of both native as well as with reduced and denatured fibrinogen and fibrin, the CNBr fragment of the fibrinogen central domain, plasmin cleaved fragments D, gamma-gamma dimers, but not with plasmic fragments E. These data indicate that J88B maps to the plasmin sensitive domain localized to gamma 63-78. MoAb J88B failed to react with synthetic peptide gamma 70-78, which suggests that the epitope includes the newly exposed N-terminal residues gamma 63-70 of the early plasmic fragment D1A. As calcium has a marked influence on plasmin cleavage of C-terminal sites on the gamma chain, the effects of calcium on modulating plasmin cleavage of D1A to D1 were assessed in the absence or presence of J88B. The results indicated that calcium delays and J88B (+/- calcium) protects the gamma chain from plasmin cleavage at the N-terminus of D1A, suggesting that this enzymatically labile site is calcium-sensitive. Thus, MoAb J88B should prove useful in studies examining the structure of plasmin cleaved fibrinogen and fibrin.
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PMID:Calcium modulates plasmin cleavage of the fibrinogen D fragment gamma chain N-terminus: mapping of monoclonal antibody J88B to a plasmin sensitive domain of the gamma chain. 894 90

Elevated plasma fibrinogen levels are a major risk factor for thrombosis. This report shows two mechanisms by which fibrinogen can affect the fibrinolysis rate in vitro and thus may lead to thrombosis. First, the lysis rate of fibrin decreases as the initial concentration of fibrinogen increases. Second, a minor variant form of fibrinogen decreases the rate of fibrinolysis. This variant, gammaA/gamma' fibrinogen, has one altered gamma chain and is known to bind to factor XIII zymogen. In a fibrinolysis assay containing purified thrombin, fibrinogen, tissue-type plasminogen activator, and plasminogen, clots from gammaA/gammaA and gammaA/gamma' fibrinogen lysed at similar rates. However, when factor XIII was added, slower lysis was seen in gammaA/gamma' fibrin clots when compared with gammaA/gammaA fibrin clots. A D-dimer agglutination assay showed that the gammaA/gamma' clots were more highly cross-linked than the gammaA/gammaA clots. The lysis rates of gammaA/gamma' clots were similar to gammaA/gammaA clots in the presence of N-ethylmaleimide, a specific inhibitor of factor XIIIa. The gammaA/gamma' fibrin clots made in the presence of factor XIII showed increased proteolytic resistance to both plasmin and trypsin. Clots made from afibrinogenemic plasma reconstituted with gammaA/gamma' fibrinogen also showed significant resistance to lysis compared with gammaA/gammaA fibrinogen. These data demonstrate gammaA/gamma' fibrin is resistant to fibrinolysis, possibly as a result of concentrating factor XIII on the clot. The total fibrinogen concentration and the amount of gammaA/gamma' fibrinogen increase clot stability in vitro and thus may contribute independently to the risk of thrombosis in humans.
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PMID:Resistance of gammaA/gamma' fibrin clots to fibrinolysis. 916 58

Coagulation and fibrinolysis universally accompany tissue injury and repair. The accumulation of regionally generated fibrin degradation products (FDP) may modify the local inflammatory response. We have found FDP to be potent neutrophil chemotaxins. We separated plasmin FDP by chromatofocusing and found chemotactic activity limited to fractions containing the fibrinogen D domain (D-D dimer and D monomer). The bioactivity of the D-D dimer did not require an intact cross link site as removal of this sequence with puff adder venom or hypocalcemic plasmic digestion did not decrease chemotaxis. Peptide inhibition studies confirmed that the chemotactic region did not involve terminal gamma chain sequences or alpha chain RGD motifs. The internal gamma chain peptide KYGWTVFQKRLDGSV (P1), known to bind CD11b/CD18, exhibited concentration dependent chemotactic activity. Similarly, monoclonal antibodies directed against CD11b/CD18 blocked PMN migration to FDP without similar inhibition of chemotaxis to IL-8 or LTB4. Thus, neutrophil chemotaxis to FDP is mediated by interactions between the fibrinogen D domain and CD11b/CD18.
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PMID:CD11b/CD18 mediates the neutrophil chemotactic activity of fibrin degradation product D domain. 918 99

The carboxyl-terminal region of the gamma chain of fibrinogen is involved in calcium binding, fibrin polymerization, factor XIIIa-mediated cross-linking, and binding to the platelet fibrin(ogen) receptor. Protein fragments encoding amino acids Val143 to Val411 (rFbggammaC30) or Val143 to Leu427 (gamma'C30) from the carboxyl end of the gamma or gamma' chains, respectively, of human fibrinogen were expressed in yeast (Pichia pastoris) and characterized as to their cross-linking by factor XIIIa, polymerization pocket, and calcium-binding site. rFbggammaC30 and gamma'C30 were both readily cross-linked by factor XIIIa, but only rFbggammaC30 was capable of inhibiting thrombin-induced platelet aggregation. Two mutants, gammaC30-Q329R and gammaC30-D364A, which were based on the three-dimensional structure of the polymerization pocket within rFbggammaC30 and on information derived from naturally occurring mutant fibrinogens, were also expressed and characterized. rFbggammaC30 inhibited (desAA)fibrin polymerization in a dose-dependent manner, while the two mutant forms did not. Similarly, rFbggammaC30 and gamma'C30 were protected from plasmin degradation by the presence of Ca2+ or the peptide Gly-Pro-Arg-Pro, indicating that a functional Ca2+-binding site and polymerization pocket are contained within each of these fragments. The mutant fragments, however, were protected from plasmin only by metal ions, while no protective effect was conferred by GPRP or by any other peptide tested. These results indicate that the polymerization pocket "a", which binds the peptide GPRP, functions independently from the nearby calcium-binding site and that amino acids Gln329 and Asp364 play a crucial role in fibrin polymerization.
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PMID:The polymerization pocket "a" within the carboxyl-terminal region of the gamma chain of human fibrinogen is adjacent to but independent from the calcium-binding site. 929 25

The 33-kDa cellular C1q binding protein, designated gC1q-R was previously shown to bind a number of plasma proteins involved in the coagulation and kinin systems. This study demonstrates the interaction between recombinant gC1q-R and fibrinogen. Using enzyme-linked immunosorbent assays, biotinylated gC1q-R was found to bind to microplate-immobilized fibrinogen in a manner which was specific and inhibited by excess soluble fibrinogen or polyclonal antibodies directed against either gC1q-R or fibrinogen. Moreover, gC1q-R inhibited fibrin polymerization in a dose-dependent manner. Reptilase induced fibrin clot formation was completely inhibited by gC1q-R at a 2:1 molar ratio (gC1q-R:fibrinogen), and repolymerization of thrombin induced fibrin monomers was similarly abrogated. At equivalent molar concentrations, gC1q-R appeared to be a more potent inhibitor of fibrin polymerization than fibrinogen, a well-known inhibitor. Moreover, in the presence of both gC1q-R and soluble fibrinogen, the effect of each inhibitor on fibrin polymerization was additive. When plasmin derived fibrinogen degradation products, including the C-terminal D domain (D-100) or the N-terminal E domain, were immobilized on microtiter plates, gC1q-R bound to fibrinogen fragment D-100, but not to fragment E. Further digestion of fibrinogen fragment D-100 by plasmin to fragment D-60 resulted in loss of gC1q-R binding. Thus, gC1q-R binds to the D domain of fibrinogen/fibrin, and the carboxyterminal segment of at least the fibrinogen/fibrin gamma chain appears important for this interaction. These observations may suggest a potential role for gC1q-R in modulating fibrin formation particularly at local sites of immune injury or inflammation.
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PMID:The receptor for the globular "heads" of C1q, gC1q-R, binds to fibrinogen/fibrin and impairs its polymerization. 1007 65

A new congenital dysfibrinogen, Fibrinogen Bastia, was discovered in a 20-year-old woman with no clinical symptoms. The plasma thrombin-clotting time was severely prolonged. The functional plasma fibrinogen concentration was low (0.2 mg/ml), whereas the immunological concentration was normal (2.9 mg/ml). Purified fibrinogen Bastia displayed a markedly prolonged thrombin-clotting time related to a delayed thrombin-induced fibrin polymerization. Both the thrombin-clotting time and the fibrin polymerization were partially corrected by the addition of calcium ions. The anomaly of fibrinogen Bastia was found to be located in the gamma-chain since by SDS-PAGE performed according to the method of Laemmli two gamma-chains were detected, one normal and one with an apparently lower molecular weight. Furthermore, analysis of plasmin degradation products demonstrated that calcium ions only partially protect fibrinogen Bastia gamma-chain against plasmin digestion, suggesting that the anomaly is located in the C-terminal part of the gamma-chain. Sequence analysis of PCR-amplified genomic DNA fragments of the propositus demonstrated a single base substitution (G-->T) in the exon VIII of the gamma chain gene, resulting in the amino acid substitution 318 Asp (GAC)-->Tyr (TAC). The PCR clones were recloned and 50% of them contained the mutation, indicating that the patient was heterozygous. These data indicate that residue Asp 318 is important for normal fibrin polymerization and the protective effect of calcium ions against plasmin degradation of the C-terminal part of the gamma-chain.
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PMID:Fibrinogen Bastia (gamma 318 Asp-->Tyr) a novel abnormal fibrinogen characterized by defective fibrin polymerization. 1061 48

A fibrinolytic enzyme, F II(a), was isolated from Agkistrodon acutus venom by ion-exchange chromatography and gel filtration. F II(a) consisted of a single polypeptide chain with a molecular weight of 26,000 and an isoelectric point of 4.6. F II(a) was shown to solubilize fibrin and fibrinogen. F II(a) cleaved, primarily, the alpha chain of fibrinogen and fibrin followed by the beta chain, while the gamma chain was minimally affected. Thus, the enzyme was an alpha,beta-fibrinogenase. The cleavage pattern of fibrinogen clearly varied from plasmin cleavage of the same molecule. In vivo, F II(a) had no influence on the rat's tissue-type plasminogen activator and plasminogen activator inhibitor-1 activities in plasma. At the dosage of 5mg/kg, histological examination of heart, liver and lung tissue showed no hemorrhage. F II(a) is an enzyme that hydrolyzed fibrin directly without hemorrhagic activity.
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PMID:Purification and biochemical characterization of F II(a), a fibrinolytic enzyme from Agkistrodon acutus venom. 1130 23

Murine models employing genetically altered mice have the potential to provide important new information about the hemostatic system, but before such data can be extrapolated to humans it is necessary to define the similarities and differences between murine and human hemostasis. After establishing the similarities of murine fibrinogen to human fibrinogen in its pattern of proteolysis in response to plasmin and its cross-linking by factor XIIIa, we studied a new hamster monoclonal antibody (mAb) 7E9 that reacts with the gamma chain of mouse fibrinogen. This antibody inhibits platelet adhesion to fibrinogen, platelet-mediated clot retraction, platelet aggregation, and FXIIIa-mediated cross-linking of fibrin; it also facilitates tissue plasminogen activator (tPA)-mediated lysis of fibrin formed either in the absence or presence of platelets. These data provide evidence that the C-terminus of mouse fibrinogen gamma chain, like that of human fibrinogen, is involved in fibrinogen binding to platelets and FXIIIa-mediated cross-linking of fibrin. Our data raise the possibility that a therapeutic agent that targets the C-terminus of the gamma chain in human fibrinogen might have broad antithrombotic and profibrinolytic effects.
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PMID:A hamster antibody to the mouse fibrinogen gamma chain inhibits platelet-fibrinogen interactions and FXIIIa-mediated fibrin cross-linking, and facilitates thrombolysis. 1168 23

Fibroblast growth factor-2 (FGF-2) binds to fibrin(ogen) with high affinity, and fibrinogen potentiates FGF-2-stimulated proliferation of endothelial cells. Because plasmin degrades fibrin(ogen) physiologically and could liberate growth factor from fibrin deposits or alter its activity, we have now investigated the effect of plasmic degradation on the activity of fibrin(ogen)-bound FGF-2. Fibrinogen with bound FGF-2 was incubated with plasmin, the products characterized by SDS-PAGE, and the proliferative activity determined by (3)H-thymidine incorporation into endothelial cells. Before plasmin exposure, proliferation was increased 3.7 +/- 0.6-fold with fibrinogen-bound FGF-2 compared with medium alone (P < 0.005). Plasmic degradation resulted in progressive decrease in the proliferative capacity, with the 60-min digest showing predominantly fragment D1 and E and (3)H-thymidine uptake of only 1.2 +/- 0.2-fold, significantly less than the activity of an equal concentration of free FGF-2 (P < 0.02). However, further degradation increased activity, and proliferation with a 90-min digest increased to 2.6 +/- 0.5-fold, significantly greater than the 60-min digest (P < 0.02). Plasmic degradation in the presence of 10 mm calcium chloride prevented degradation of D1 to D2 and D3, and the activity did not increase with extended degradation. Immunoprecipitation of the digests with antifibrinogen antibody showed 70 +/- 8% of fibrinogen-bound FGF-2 in the presence of calcium but only 15 +/- 4% in its absence, indicating that cleavage of D1 to D2 and D3 is critical in binding. Fragment D1 and D2, but not D3, bound to a column containing immobilized FGF-2, indicating that a binding site is lost upon degradation to D3. The results demonstrate that plasmic degradation of fibrinogen modulates the activity and binding of FGF-2 that involves a site near the carboxyl terminus of the gamma chain.
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PMID:Plasmic degradation modulates activity of fibrinogen-bound fibroblast growth factor-2. 1287 30


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