Comparison of kinin-forming and amidolytic activities of four trimucases, oedema-producing and kinin-releasing enzymes, from Trimeresurus mucrosquamatus venom.

Four kinin-releasing enzymes, trimucase I, II, III and IV, isolated from Trimeresurus mucrosquamatus venom (TMV) caused rat hind-paw swelling. Trimucase I and III were less potent than trimucase II and IV in this effect. Pretreatment with diphenhydramine or methysergide significantly reduced trimucase-induced paw swelling, while aspirin had no effect. Cellulose sulphate pretreatment suppressed the oedematous responses elicited by trimucases. The residual response was further depressed by diphenhydramine and methysergide. Trimucases also caused kinin generation in-vitro from rat plasma. This kinin-forming activity was in the order of trimucase II greater than IV greater than or equal to III greater than I greater than TMV. All trimucases hydrolysed chromogenic peptides N-benzoyl-Pro-Phe-Arg p-nitroanilide, N-benzoyl-Phe-Val-Arg p-nitroanilide and DL-Val-Leu-Arg p-nitroanilide; the order of this amidolytic activity was trimucase I greater than II greater than III greater than or equal to IV. These data indicate that the effects of venom kinin-releasing enzymes on plasma kininogen are not parallel to their amidolytic effects.