Crystal structure of myotoxin II, a monomeric Lys49-Phospholipase A(2) homologue isolated from the venom of Cerrophidion (Bothrops) godmani

Lys49-Phospholipase A(2) (Lys49-PLA(2)) homologues damage membranes by a Ca 2+-independent mechanism which does not involve catalytic activity. With th e aim of determining the structural basis for this novel activity, we have solved the crystal structure of myotoxin-II, a Lys49-PLA(2) isolated from t he venom of Cerrophidion (Bothrops) godmani (godMT-II) at 2.8 Angstrom reso lution by molecular replacement. The final model has been refined to a fina l crystallografic residual (R-factor) of 18.8% (R-free = 28.2%), with excel lent stereochemistry. godMT-II is also monomeric in the crystalline state, and small-angle X-ray scattering results demonstrate that the protein is mo nomeric in solution under fisicochemical conditions similar to those used i n the crystallographic studies. (C) 1999 Academic Press.