A new muscle damaging toxin, myotoxin II, from the venom of the snake Bothrops asper (terciopelo).

A new muscle damaging toxin, myotoxin II, was purified from the venom of Bothrops asper by ion-exchange chromatography on CM-Sephadex C-25. The toxin is a dimeric, basic protein with a monomer mol.wt of 13,341, according to the amino acid composition, and 16,000 on the basis of SDS-polyacrylamide gel electrophoretic mobility. It has a high number of aspartate and lysine residues, as well as of hydrophobic amino acids. Upon i.m. injection into mice, the toxin induces myonecrosis and increase in serum creatine kinase levels. In addition, myotoxin II induces edema in the mouse foot pad. Immunochemical tests, mol.wt, and amino acid composition indicate a high degree of homology between myotoxin II and a previously characterized myotoxin from this venom, myotoxin I. However, in contrast to myotoxin I, myotoxin II lacks phospholipase A2 and anticoagulant activities in vitro.