Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.4.21.6 (thromboplastin)
 13,278 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Single-chain human recombinant factor VII produced by transfected baby hamster kidney cells was purified to homogeneity in the presence of benzamidine. The amidolytic activity of single-chain recombinant factor VII with a peptidylnitroanilide substrate, methoxycarbonyl-D-cyclohexanylglycyl-L-arginine-p-nitroanilide, was less than 1% of that obtained with factor VIIa. Purified single-chain recombinant factor VII spontaneously activated in the absence of inhibitor. The activation reaction was enhanced by at least 2 orders of magnitude in the presence of a positively charged surface, provided either as an anion-exchange matrix or as poly(D-lysine). The progress curve for factor VIIa generation was sigmoidal. Benzamidine inhibits recombinant factor VIIa activity and factor VII activation with identical inhibition constants (Ki) of 11 mM. In contrast, benzamidine inhibition of bovine factor Xa and bovine factor IIa was observed at Ki values equal to 0.3 and 0.5 mM, respectively. Bovine factors Xa and IIa are known activators of factor VII and the most likely contaminants of our recombinant factor VII preparations. Single-chain recombinant factor VII purified from cells cultured in the absence of bovine serum activated at the same rate as factor VII from cells cultured in the presence of bovine serum. This also excluded the possibility that the activation reaction was caused by contaminating bovine proteases. On the basis of these observations, we propose that factor VII is autoactivated in vitro in the presence of a positively charged surface.
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PMID:Autoactivation of human recombinant coagulation factor VII. 261 Dec 33

An anticoagulant activity was identified and isolated from the leaves of a West African plant, Aspilia africana by gel filtration on Sephadex G-100. The anticoagulant factor had an apparent molecular weight of approximately 60,000 d. Upon incubation with plasma, it prolonged the partial thromboplastin time, prothrombin time, thrombin and reptilase time. The factor decreased the fibrinogen content of plasma as well as the activity of coagulation factors V, VIII and IX but not factor VII, X or XI activities. After incubation with fibrinogen, the thrombin clotting time was prolonged and the quantity of clottable fibrinogen reduced. The action on fibrinogen was characterized by sequential lytic breakdown of the A-alpha-chain and B-beta-chain, the gamma-chain being lysed last, after prolonged incubation. Benzamidine, Epsilon aminocaproic acid or soybean trypsin inhibitor did not impede lysis.
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PMID:Studies on the anticoagulant action of Aspilia africana. 366 Mar 50

Bothrops colombiensis venom from two similar geographical locations were tested for their hemostatic functions and characterized by gel-filtration chromatography and SDS-PAGE electrophoresis. The snakes were from Caucagua and El Guapo towns of the Venezuelan state of Miranda. Fibrino(geno)lytic, procoagulant, hemorrhagic, lethal activities, gel-filtration chromatography and SDS-PAGE profiles were analyzed and compared for both venoms. The highest hemorrhagic activity of 5.3 mug was seen in El Guapo venom while Caucagua venom had the lowest LD(50) of 5.8 mg/kg. Both venoms presented similar thrombin-like activity. El Guapo showed a factor Xa-like activity two times higher than Caucagua. Differences were observed in kallikrein-like and t-PA activities, being highest in El Guapo. Caucagua venom showed the maximum fibrin lysis. Both crude venom runs on Sephadex G-100 chromatography gave fraction SII with the high fibrinolytic activity. Proteases presented in SII fractions and eluted from Benzamidine-Sepharose (not bound to the column) provoked a fast degradation of fibrinogen alpha chains and a slower degradation of beta chains, which could possibly be due to a higher content of alpha fibrinogenases in these venoms. The fibrinogenolytic activity was decreased by metalloprotease inhibitors. The results suggested that metalloproteases in SII fractions were responsible for the fibrinolytic activity. The analysis of samples for fibrin-zymography of SII fractions showed an active band with a molecular mass of approximately 30 kDa. These results reiterate the importance of using pools of venoms for antivenom immunization, to facilitate the neutralization of the maximum potential number of toxins.
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PMID:Hemorrhagic, coagulant and fibrino(geno)lytic activities of crude venom and fractions from mapanare (Bothrops colombiensis) snakes. 1793 91