A quick procedure for the isolation of dimeric piratoxins-I and II, two myotoxins from Bothrops pirajai snake venom. N-terminal sequencing.

Two myotoxins, MP-I and MP-II, from Bothrops pirajai snake venom, have been purified by a quick high performance liquid chromatography (HPLC) procedure. Based on the HPLC coelution profile, amino acid composition, N-terminal sequence, polyacrylamide gel electrophoresis (PAGE) migration, as well as lack of phospholipase-A2 (PLA2) and proteolytic activities, MP-I and MP-II were identified as piratoxin-I (PrTX-I) and II (PrTX-II), respectively. This procedure affords, aside the reduced operation time, a high yield (35% of the applied sample in terms of A280nm) of MP-I, which is the major myotoxin of the venom. The N-terminal sequences of MP-I, MP-II, PrTX-I and PrTX-II, up to the 51st, 41st, 46th and 39th residues, respectively, have been determined, revealing MP-I (and hence PrTX-I) as a Lys-49 PLA2-like myotoxin. Both MP-I and MP-II have been shown, by SDS-PAGE, to occur in dimeric isoforms.