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)

Prothrombin isolated from duck sodium citrate plasma was activated in a system containing duck factor Xa and calcium ions. Polyacrylamide gel electrophoresis showed that intermediates and the final product, thrombin, of Mr in the range 21 500-52 000 were present in the incubation mixture Serine and isoleucine were found to be the N-terminal amino acids of the intermediate form 1 and thrombin, respectively.
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PMID:Activation of duck prothrombin by factor Xa and thrombin. 383 1

An antithrombin III (AT III) functional defect (AT III Charleville) was discovered in a patient presenting with recurrent venous thrombosis. Both anti-activated factor X (anti Xa) and antithrombin activity were decreased, in the absence and in the presence of heparin, while protein concentration was normal in an immunological assay. The abnormal AT III copurified with functional AT III using insolubilized heparin affinity chromatography. Polyacrylamide gel electrophoresis (PAGE) and high pressure liquid chromatography (HPLC) on a TSK column suggest that AT III Charleville forms unstable complexes with thrombin from which a modified protein is rapidly released.
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PMID:A functional abnormal antithrombin III (AT III) deficiency: AT III Charleville. 408 1

A protease purified from the venom of the elapid snake Naja naja oxiana converts human blood coagulation factor Va into a molecule (factor VaNO) with greatly reduced cofactor activity. Polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate revealed that the venom protease cleaved a small peptide from the heavy chain of factor Va and reduced the apparent M(r) from 105,000 to 101,000. This peptide was isolated by high performance liquid chromatography on a reversed-phase column. Amino acid sequence analysis of the peptide indicated that the venom enzyme cleaved the peptide bond between His682 and Asp683, thus removing 27 amino acids from the carboxyl-terminal part of the heavy chain. The cofactor activities of factors Va and VaNO were compared by measuring their abilities to support factor Xa-catalyzed prothrombin activation in the presence of phospholipids and calcium ions. Both factor Va molecules stimulated the binding of factor Xa to negatively charged phospholipids. However, the amounts of factor Va required for half-maximal incorporation of factor Xa into the membrane-bound factor Xa-Va complex were much lower for native factor Va (0.25 nM) than for factor VaNO (2.01 nM). At saturating concentrations of factor Va or factor VaNO the kcat values for prothrombin activation were 114 s-1 for factor Va and 128 s-1 for factor VaNO. The Km values for prothrombin determined under these conditions were 0.24 and 0.83 microM for prothrombinase complexes with native factor Va and factor VaNO, respectively. Direct binding studies revealed that factors Va and VaNO bind with equal affinity to phospholipids. These data indicate that factor VaNO is impaired in its ability to interact with factor Xa and prothrombin. Together with the structural data this implies that the carboxyl-terminal Asp683-Arg709 domain of the heavy chain is required for optimal interaction of factor Va with factor Xa and prothrombin.
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PMID:Functional properties of human factor Va lacking the Asp683-Arg709 domain of the heavy chain. 805 Nov 66