Purification, Partial Characterizations, and N-Terminal Amino Acid Sequence of a Procoagulant Protein FV-2 from Daboia Russelli Siamensis (Myanmar) Venom.

In this study, we purified and characterized the procoagulant protein FV-2 from Daboia russelli siamensis (Myanmar) venom using ion-exchange chromatography on CM-Sephadex C-50 and gel filtration on Superdex G-75 column. The activation of factor X and prothrombin was determined, respectively, by specific chromogenic substrates. The fibrinogen-clotting activity, thermal stability, and pH stability were also determined. The N-treminal sequence was determined by the National Center of Biomedical Analysis of China. In the end, FV-2 was achieved with a molecular weight of 13,608.0 Da. It could activate factor X, but did not affect prothrombin or fibrinogen. The suitable pH was 6.5-7.5, and the suitable temperature ranged from 25 to 60°C. The N-terminal sequence was Asn-Phe-Phe-Gln-Phe-Ala-Glu-Met-Ile-Val-Lys-Met-Thr-Gly-Lys. Taken together, our studies suggest that FV-2 is a factor X-activating enzyme, which can activate factor X to factor Xa, but it has no effect on prothrombin and fibrinogen.