Purification, properties, and N-terminal amino acid sequence of a kallikrein-like enzyme from the venom of Lachesis muta rhombeata (Bushmaster).

Pit viper venoms contain multiple proteinases which cause considerable damage in tissues and systemic effects after envenomation. A proteinase, kallikrein-like enzyme, belonging to the serine group must play a very important role on systemic effects. The corresponding enzyme from Lachesis muta rhombeata venom was purified to homogeneity by a combination of isoelectrofocusing fractionation followed by one step of gel filtration HPLC. The enzyme focused with pI 5.0-6.5, it had a molecular mass of 32 kDa by gel filtration HPLC, had edematogenic activity, and induced a hypotensic effect in anesthetized rats. It exhibited strong N-alpha-tosyl-L-Arg methyl esterase (955.38 units/mg) and N-Bz-DL-Arg-pNA amidolytic (233.02 units/mg) activities, hydrolyzed tripeptide nitroanilide derivatives weakly or not at all, and cleaved selectively the A-alpha and B-beta chains of fibrinogen, apparently leaving the Y-chain unaffected. The 30 N-terminal amino acid sequence of the L. m. rhombeata protein showed greatest identity (74% in 26 amino acids) with Crotalus viridis kallikrein-like protein, but significant similarities in sequence were observed with enzymes from other snake venoms and pig pancreatic kallikrein.