Characterization of a basic phospholipase A(2)-homologue myotoxin isolatedfrom the venom of the snake Bothrops neuwiedii (yarara chica) from Argentina

A basic protein was isolated by CM-Sephadex C-25 chromatography from the ve nom of Bothrops neuwiedii from Argentina, and named B. neuwiedii myotoxin I . This protein exerted local myotoxic and edema-forming effects in mice, wi th potencies comparable to other myotoxins isolated from Bothrops spp, veno ms. When injected by i.v. route at doses up to 4.7 mg/kg of body weight, th e toxin was not lethal. In vitro, the toxin had no detectable phospholipase A(2) activity on egg yolk phospholipids. B. neuwiedii myotoxin I appeared as a homodimer in sodium dodecylsulphate-polyacrylamide gel electrophoresis , with a subunit molecular weight of 15 kD. Gel immunodiffusion revealed a pattern of partial antigenic identity between the newly isolated myotoxin a nd myotoxin II from Bothrops asper venom. The sequence of B. neuwiedii myot oxin I was determined for the first 40 amino acid residues, showing high ho mology to several class II phospholipase A(2) myotoxins of the Lys-49 famil y from crotalids. Altogether, results suggest that this toxin is a new memb er of the Lys-49 phospholipase A(2)-homologues with myotoxic, cytolytic, an d edema-inducing activities. (C) 1999 Elsevier Science Ltd. All rights rese rved.