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Structural Requirements for Expression of Factor Va Activity.
- Source :
-
Journal of Biological Chemistry . 8/29/2003, Vol. 278 Issue 35, p33550-33561. 12p. 1 Diagram, 1 Chart, 8 Graphs. - Publication Year :
- 2003
-
Abstract
- Thrombin activated factor Va (factor V[sub IIa], residues 1-709 and 1546-2196) has an apparent dissociation constant (K[sub d,app]) for factor Xa within prothrombinase of ∼0.5 nM. A protease (NN) purified from the venom of the snake Naja nigricollis nigricollis, cleaves human factor V at Asp[sup 697], Asp[sup 1509], and Asp[sup 1514] to produce a molecule (factor V[sub NN]) that is composed of a M[sub r] 100,000 heavy chain (amino acid residues 1-696) and a M[sub r] 80,000 light chain (amino acid residues 1509/1514-2196). Factor V[sub NN], has a K[sub d,app] for factor Xa of 4 nM and reduced clotting activity. Cleavage of factor V[sub IIa] by NN at Asp[sup 697] results in a cofactor that loses ∼60-80% of its clotting activity. An enzyme from Russell's viper venom (RVV) cleaves human factor V at Arg[sup 1018] and Arg[sup 1545] to produce a M[sub r] 150,000 heavy chain and M[sub r] 74,000 light chain (factor V[sub RVV], residues 1-1018 and 1546-2196). The RVV species has affinity for factor Xa and clotting activity similar to the thrombin-activated factor Va. Cleavage of factor V[sub NN] at Arg[sup 1545] by α-thrombin (factor V[sub NN/IIa]) or RVV (factor V[sub NN/RVV]) leads to enhanced affinity of the cofactor for factor Xa (K[sub d,app] ∼ 0.5 nM). A synthetic peptide containing the last 13 residues from the heavy chain of factor Va (amino acid sequence 697-709, D13R) was found to be a competitive inhibitor of prothrombinase with respect to prothrombin. The peptide was also found to specifically interact with thrombin-agarose. These data demonstrate that 1) cleavage at Arg[sup 1545] and formation of the light chain of factor V[sub IIa] is essential for high affinity binding and function of factor Xa within prothrombinase and 2) a binding site for prothrombin is contributed by amino acid residues 697-709 of the heavy chain of the cofactor. [ABSTRACT FROM AUTHOR]
- Subjects :
- *HEMOSTASIS
*ENZYMES
*THROMBIN
*PROTHROMBIN
Subjects
Details
- Language :
- English
- ISSN :
- 00219258
- Volume :
- 278
- Issue :
- 35
- Database :
- Academic Search Index
- Journal :
- Journal of Biological Chemistry
- Publication Type :
- Academic Journal
- Accession number :
- 11013691
- Full Text :
- https://doi.org/10.1074/jbc.M303153200