Structure of a Lys49 phospholipase A(2) homologue isolated from the venom of Bothrops nummifer (jumping viper)

Lys49-Phospholipase A(2) (Lys49-PLA(2)) homologues damage membranes by a Ca 2+-independent mechanism which does not involve catalytic activity, We have solved the structure of myotoxin-I, a Lys49-PLA(2) homologue isolated from the venom of Bothrops nummifer (jumping viper) at 2.4 Angstrom resolution using molecular replacement techniques. The final model has been refined to a final R-factor of 18.4% (R-free = 23.2%), and shows excellent geometry, The myotoxin-I from Bothrops nummifer is dimeric in the crystalline state a s has been observed for other Lys49-PLA(2) homologues. In addition, a conti nuous electron density in the active site and substrate binding channel cou ld be successfully modeled as a fatty-acid molecule. (C) 1999 Elsevier Scie nce Ltd, All rights reserved.