Fibrinogenolytic Properties of Proteolytic Fractions Isolated From the Venom of the Levant Viper (Vipera Lebetina Turanica)

The fibrinogenolytic properties of proteolytic fractions isolated from the venom of the Levant viper (Vipera lebetina turanica) were investigated. The venom was fractionated by gel-filtration chromatography on Sephacryl S-200 and subsequently on Superose-12. Human fibrinogen (1 %) was incubated with the Superose-12 fractions for 3 h at 37 °C, and the degradation of the individual polypeptide chains was analysed by 10 % SDS-PAGE under denaturing conditions. Electrophoretic analysis showed that the proteolytic complex of the venom acts selectively on the Aα and Bβ chains of fibrinogen, whereas the γ-chain remained intact in all fractions examined. Fractions of higher molecular mass (≥76–43 kDa) degraded the Aα-chain first, followed more slowly by the Bβ-chain, whereas fractions of lower molecular mass (≤43–25 kDa) showed preferential selectivity towards the Bβ-chain. Differences in the pattern of degradation products between fractions indicate the presence of at least two groups of fibrinogenases with distinct substrate specificity within the V. lebetina turanica venom proteolytic complex. The fibrinolytic activity of the Sephacryl S-200 fractions was assessed separately by the fibrin plate assay, in which fraction III-1 produced the largest lysis zone. Because fibrinogenolysis and fibrinolysis are distinct processes, these two sets of results are interpreted independently.