Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.4.21.5 (thrombin)
 33,306 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The effect of a 17-kringle form of recombinant apo(a) [r-apo(a)] on in vitro fibrin clot lysis was studied. In these assays, fibrin clots were formed in the wells of microtiter plates, and lysis of the clots was monitored by measurement of the turbidity at 405 nm. The results indicate that r-apo(a) produces a dose-dependent antifibrinolytic effect in clots formed using either purified components or barium-adsorbed plasma. This effect was found to be independent of clot structure, since lysis of clots formed using both high and low concentrations of thrombin was prolonged by r-apo(a) to the same extent. The two components of the antifibrinolytic effect of r-apo(a) were determined to be (i) attenuation of tPA-mediated plasminogen activation (the major component) and (ii) inhibition of plasmin degradation of fibrin, although r-apo(a) did not directly attenuate plasmin activity, as measured by S-2251 hydrolysis. r-Apo(a) interfered most substantially with tPA-mediated activation of Glu-plasminogen and less substantially with tPA-mediated Lys-plasminogen activation and urokinase-mediated activation of plasminogen. In summary, we have demonstrated that apo(a) is able to attenuate fibrin clot lysis in vitro, primarily as a consequence of the interference by apo(a) with tPA-mediated Glu-plasminogen activation. These studies illuminate possible mechanisms by which Lp(a) may contribute to the development of vascular disease in vivo.
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PMID:Antifibrinolytic effect of recombinant apolipoprotein(a) in vitro is primarily due to attenuation of tPA-mediated Glu-plasminogen activation. 771 Oct 34

A portion of kringle IV37 (KIV37) of apolipoprotein (a), (apo(a)), was polymerase chain reaction-cloned from human liver cDNA. The protein product of this clone was expressed in Escherichia coli as a poly histidine fusion protein. Based on recovery of purified fusion apo(a) KIV37 protein expression levels were estimated to be 10 mg/g of E. coli cell paste. Mass spectral analysis showed the molecular mass of fusion apo(a) KIV37 to be 12,260 +/- 1 daltons. Almost all fusion apo(a) KIV37 was expressed as inclusion bodies and had to be refolded. Fusion apo(a) KIV37 was isolated from the inclusion bodies and purified by lysine-Sepharose affinity chromatography by eluting with 0.2 M epsilon-aminocaproic acid. The fusion protein was treated with thrombin to yield a homogeneous, functional apo(a) KIV37 domain composed of 92 amino acids having a molecular mass of 10,510 +/- 1 daltons. N-terminal protein sequencing and amino acid analysis have confirmed the sequence and composition of apo(a) KIV37. The molar extinction coefficient, epsilon, for apo(a) KIV37 was determined to be 3.1 x 10(4) M-1 cm-1, and the pI was measured to be 6.7 +/- 0.1. In addition, the dissociation constants, Kd, for a series of 11 lysine analogs have been determined by measuring the change in intrinsic fluorescence of apo(a) KIV37 upon saturable binding with these compounds. Kd values ranged from 4.2 +/- 0.9 microM for trans-4-(aminomethyl)cyclohexanecarboxylic acid to 4.6 +/- 0.4 mM for L-arginine. Apo(a) KIV37 binds to plasmin-treated fibrinogen with an EC50 value of 14 +/- 1.2 microM and prevents the binding of Lp(a) to plasmin-treated fibrinogen with an IC50 value of 16 +/- 6 microM. Lp(a) binds to the plasmin-treated fibrinogen surface with an EC50 value of approximately 1.0 +/- 0.3 nM. These studies demonstrate that apo(a) KIV37 can be expressed at high levels, refolded properly, and used as a fully functional lysine-binding domain. In addition, these results also demonstrate that apo(a) KIV37 provides the major interaction of Lp(a) with fibrinogen. One additional weak binding site in Lp(a) is adequate to describe overall Lp(a) binding to fibrinogen.
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PMID:Cloning, expression, and characterization of human apolipoprotein(a) kringle IV37. 806 25

The relation of habitual diet and cardiorespiratory fitness to plasma fibrinogen concentration, Factor VII activity (F VIIc), Factor X activity (F X), tissue plasminogen activator (t-PA), plasminogen activator inhibitor 1 (PAI-1) concentrations, anti-thrombin III (AT III) and apolipoprotein(a) (Apo[a]) was analyzed in 111 normolipidemic men aged 51-53 years. Diet was evaluated by seven day food records. Maximal oxygen consumption and aerobic threshold were determined in maximal bicycle ergospirometry test based on breath-by-breath analysis of expired respiratory gas. Plasma fibrinogen was measured by thrombin method, F VIIc by one-stage coagulation method, AT III and F X colorimetrically, t-PA and PAI-1 antigens by ELISA and Apo(a) concentration radioimmunologically. Carbohydrate intake was negatively (r = -0.31, p < 0.001; r = -0.24, p < 0.01; r = -0.36, p < 0.001) and fat intake positively (r = 0.24, p < 0.01; r = 0.29, p < 0.001; r = 0.32, p < 0.001) related to F X, PAI-1, and t-PA, respectively. Aerobic threshold correlated negatively with fibrinogen (r = -0.33, p < 0.001) and F X (r = -0.30, p < 0.001). Fasting insulin was the strongest determinant for PAI-1 (r = 0.55, p < 0.001) and a significant positive correlate to F VIIc (r = 0.30, p < 0.001), F X (r = 0.28, p < 0.01) and t-PA (r = 0.47, p < 0.001). These data emphasize the importance that carbohydrate rich diet and cardiorespiratory fitness may have against thrombogenesis.
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PMID:Relation of habitual diet and cardiorespiratory fitness to blood coagulation and fibrinolytic factors. 819 95