Activation of the fibrin stabilizing factor of plasma by thrombin

Lóránd, L.; Konishi, Kazuhiko

doi:10.1016/0003-9861(64)90235-8

Cited by 235 publications

(106 citation statements)

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“…It should be stressed that thrombin that is generated via this amplification loop is formed inside the growing "haemostatic plug", where it is bound to fibrin and prevented from inactivation by endogenous thrombin inhibitors such as antithrombin and α2-macroglobulin [27]. An addtional function of thrombin is its activation of FXIII, which, unlike the other coagulation factors, is a transglutaminase, which cross-links fibrin strands to further strengthen the "plug" and to induce its retraction [30]. Conversion of fibrinogen into fibrin and co-factor activation is not the only physiological functions of thrombin.…”

Section: Blood Coagulationmentioning

confidence: 99%

Inhibition of carboxypeptidase U (TAFIa) activity improves rt-PA induced thrombolysis in a dog model of coronary artery thrombosis

Björkman

Abrahamsson

Nerme

et al. 2005

Thrombosis Research

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The physiologically most important activator of intravascular fibrinolysis is tissue-type plasminogen activator (t-PA) released from endothelial cells. In man, sympathomimetic drugs increase the systemic concentration of t-PA. It is therefore of interest to investigate whether cardiac sympathetic activation can induce a local t-PA release, which could counteract intra-coronary clot formation.Thrombolytic therapy with recombinant t-PA (rt-PA) is effective in acute myocardial infarction, but the treatment is limited by a fairly slow reperfusion rate and frequent early reocclusions. A potential mechanism behind early reocclusions might be that active thrombin is released from the thrombus during thrombolytic therapy. Thrombin has recently been shown to activate procarboxypeptidase U, which in its active form (CPU) down-regulates endogenous fibrinolysis. Therefore, one way of improving thrombolytic efficacy may be to combine rt-PA with a lowmolecular weight direct thrombin inhibitor, which theoretically could have a pro-fibrinolytic effect, either by inhibition of fibrin-bound thrombin and/or by inhibition of CPU activation. An alternative way may be direct inhibition of CPU.In a porcine model, experimental activation of cardiac sympathetic nerves by electrical stimulation at 1 and 8 Hz induced 5-and 20-fold increase in the release of both total and active t-PA together with frequency-dependent increases in heart rate, blood pressure, and coronary blood flow. The t-PA release was independent of the heart rate and coronary flow response, but local infusion of isoprenaline suggested that part of the t-PA response was mediated by stimulation of β-adrenergic receptors. Next, we studied the combined effect of rt-PA and thrombin inhibitors (melagatran, hirudin and heparin) in a canine model of copper coil-induced coronary thrombosis. The profibrinolytic effect of rt-PA, either measured as patency rate or time-to-patency, was significantly enhanced with the low-molecular weight direct thrombin inhibitor melagatran, but to a lesser degree by hirudin and heparin. In the same model it was shown that active CPU is produced locally in the coronary vascular bed during both thrombus formation and clot lysis. Inhibition of thrombin attenuated CPU formation and improved patency. A similar effect was obtained with a direct inhibitor of CPU.In conclusion, the coronary t-PA response to sympathetic stimulation may constitute a thromboprotective defence mechanism to counteract its prothrombotic effects on the systemic level. Furthermore, direct thrombin and/or CPU inhibition may be potential targets for prevention of thrombus formation via facilitation of the endogenous fibrinolytic system.

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Section: Blood Coagulationmentioning

confidence: 99%

Inhibition of carboxypeptidase U (TAFIa) activity improves rt-PA induced thrombolysis in a dog model of coronary artery thrombosis

Björkman

Abrahamsson

Nerme

et al. 2005

Thrombosis Research

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“…Platelet and placental fXIII are homodimers composed of two identical A chains, but plasma fXIII is a heterotetramer composed of two A and two B chains (10). Plasma fXIII is activated by two steps: 1) thrombin cleavage of a 4 kDa fragment from the N terminus of the A-chains and 2) Ca-dependent dissociation of the two B chains from the tetramer, yielding functionally active A-chain dimers (XIIIa) (11,12). FXIII was discovered in 1948 (13), and since that time has been extensively studied.…”

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confidence: 99%

Coagulation Factor XIIIa Undergoes a Conformational Change Evoked by Glutamine Substrate

Mitkevich

Shainoff

DiBello

et al. 1998

Journal of Biological Chemistry

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Coagulation factor XIIIa, plasma transglutaminase (endo-␥-glutamine:⑀-lysine transferase EC 2.3.2.13) catalyzes isopeptide bond formation between glutamine and lysine residues and rapidly cross-links fibrin clots. A monoclonal antibody (5A2) directed to a fibrinogen A␣-chain segment 529 -539 was previously observed from analysis of end-stage plasma clots to block fibrin ␣-chain cross-linking. This prompted the study of its effect on nonfibrinogen substrates, with the prospect that 5A2 was inhibiting XIIIa directly. It inhibited XIIIa-catalyzed incorporation of the amine donor substrate dansylcadaverine into the glutamine acceptor dimethylcasein in an uncompetitive manner with respect to dimethylcasein utilization and competitively with respect to dansylcadaverine. Uncompetitive inhibition was also observed with the synthetic glutamine substrate, LGPGQSKVIG. Theoretically, uncompetitive inhibition arises from preferential interaction of the inhibitor with the enzyme-substrate complex but is also found to inhibit ␥-chain cross-linking. The conjunction of the uncompetitive and competitive modes of inhibition indicates in theory that this bireactant system involves an ordered reaction in which docking of the glutamine substrate precedes the amine exchange. The presence of substrate enhanced binding of 5A2 to XIIIa, an interaction deemed to occur through a C-terminal segment of the XIIIa A-chain (643-658, GSDMTVTVQFT-NPLKE), 55% of which comprises sequences occurring in the fibrinogen epitope A␣-(529 -540) (GSESGIFTNTKE). Removal of the C-terminal domain from XIIIa abolishes the inhibitory effect of 5A2 on activity. Crystallographic studies on recombinant XIIIa place the segment 643-658 in the region of the groove through which glutamine substrates access the active site and have predicted that for catalysis, a conformational change may accompany glutamine-substrate binding. The uncompetitive inhibition and the substrate-dependent binding of 5A2 provide evidence for the conformational change.

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“…7, normal plasma displays no amine-incorporating activity in the absence of thrombin; only the precursor is present. The enzyme is produced transiently (7,28) after the appearance of thrombin. As a transpeptidase, FSF* is similar in its mode of action to other enzymes such as liver transglutaminase and muscle tissue coagulin (31).…”

Section: Discussionmentioning

confidence: 99%

Diagnostic and genetic studies on fibrin-stabilizing factor with a new assay based on amine incorporation

Lóránd¹,

Urayama²,

Kiewiet³

et al. 1969

J. Clin. Invest.

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212

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A B S T R A C T Fibrinoligase, the fibrin cross-linking enzyme, transiently appearing during the course of coagulation in normal blood, was shown to catalyze the incorporation of a fluorescent amine, monodansylcadaverine [or N-( 5-aminopentyl) -5-dimethylamino-1-naphthalenesulfonamide] into casein. The reaction provided the basis of a sensitive fluorimetric method for measuring the activity of the enzyme (and also of similar other transpeptidases, such as transglutaminase).In tests involving plasma, certain difficulties had to be overcome which were mainly due to the fact that the enzyme itself does not occur in citrated plasma. Only its precursor (fibrin-stabilizing factor or factor XIII) is present, still requiring limited proteolytic activation by thrombin. Thus, in order to measure amine incorporation with plasma as a source of the factor, thrombin must be added. This necessitated a differential desensitization of the intrinsic fibrinogen so that the latter could not clot and could not thereby interfere with amine incorporation. Also, the thrombin-inactivating capacity of plasma had to be saturated to enable full conversion of the factor to the transpeptidase. Concentrations of casein, monodansylcadaverine, calcium, and hydrogen ions were chosen to permit almost maximal velocity of amine incorporation. A linear relationship with regard to plasma concentration could be obtained only under such conditions. No similar assay is presently available for quantitatively evaluating fibrin-stabilizing factor levels in plasma.

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Activation of the fibrin stabilizing factor of plasma by thrombin

Cited by 235 publications

References 22 publications

Inhibition of carboxypeptidase U (TAFIa) activity improves rt-PA induced thrombolysis in a dog model of coronary artery thrombosis

Inhibition of carboxypeptidase U (TAFIa) activity improves rt-PA induced thrombolysis in a dog model of coronary artery thrombosis

Coagulation Factor XIIIa Undergoes a Conformational Change Evoked by Glutamine Substrate

Diagnostic and genetic studies on fibrin-stabilizing factor with a new assay based on amine incorporation

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