Crystal structure of piratoxin I at 2.4 A Angstrom resolution

Full text. We have been investigating a class of PLA2-homologues in which Lys substitutes for the highly conserved Asp49. Since the Asp49 is essential in the binding of Ca+ ions as a co-factor, the replacement by lysine results in no enzymatic activity yet still demage membranes by a poorly understood mechanism of action. The venom from B. pirajai is one of those least investigated, and as part of our ongoing structural studies of K49 PLA2- homologues, we have crystallized and determined the structure of piratoxin I. The crystals belong to the space group P21 2121 (a=67.58 A, b=87.85 A and c=50.43 A). X-ray diffraction data was collected to 2.4 A resolution using an RAXIS IIC imaging plate detector. The structure has been refined to a crystallographic residual of 21.7%. Structural details and comparisons with other K49 PLA2's will be presented. (author)