Crystal structure of an acidic phospholipase A2 from the venom of Agkistrodon halys pallas at 2.0 A resolution.

Abstract The crystal structure of acidic phospholipase A 2 from the venom of Agkistrodon halys pallas has been determined by molecular replacement at 2.0 A resolution to a crystallographic R -factor of 0.157. The overall structure of the molecule is very similar to those of other phospholipase A 2 species of known structure. The catalytic site, the hydrophobic channel and the N-terminal region show greatest structural conservation. The Ca 2+ -binding region has a conformation that resembles closely that of bovine PLA 2 rather than Crotalus atrox PLA 2 . Compared with other PLA 2 species, the conformation of the C-terminal ridge shows significant difference due to the insertion of two residues. A unique aromatic patch appears on one face of the molecules, surrounded by two acidic residues, the relevant features of this structure and their possible biological implications are discussed.