Purification of a myotoxin from the toadfish Thalassophryne maculosa (Günter) venom

Venom was milked by gently pressing the base of the opercular and dorsal fin spines. Three fractions were obtained by molecular exclusion high pressure liquid chromatography (HPLC) (Protein Pak™ 125SW, Millipore Corporation) column, but only the last one with 22.7 min retention time (rt) was biological active (TmPP-22.7). This fraction was rechromatographed on reversed phase HPLC chlorobutylsilane columns (C4, Vydac) nine fractions were obtained, but only one (TmC4-47.2) with 47.2 min rt was biologically active. MALD-TOF mass analysis was carried out on two samples of TmC-47.2 and the results were 15,161.36 and 15,154.70 a.m.u., respectively. Raw venom (1040 μg/ml) depolarised frog (Hyla crepitans) muscle irreversibly from −85 (−88, −81) mV (n=20, median and its 95% CI) to −18 (−24, −15) mV (n=24). The biological activity in TmPP-22.7 (38 μg/ml), which depolarised muscle fibres from −79 (−82, −76) mV (n=20) to −63 (−69 −57) mV (n=24). The depolarising fraction was TmC4-47.2 (50 μg/ml) which depolarised muscles from −87 (91, −82) mV (n=33) to −63 (−76 −51) mV (n=53); the depolarising effect at this concentration was completely reversed on washing with normal saline for 2 h. Muscles treated with 1 μM tetrodotoxin (TTX) were depolarised from −80 (−85, −72) mV (n=49) to −44 (−56, −31) mV (n=44) when 100 μg/ml TmC4-47.2 were applied with TTX; washing 130 min with 1 μM TTX repolarised to −59 (−69, −50) mV (n=25). We also present evidence that TmC4-47.2 induces myonecrosis in mice.