Abstract
The reaction mechanism of the 14 kDa secreted phospholipases A2 (PLAs) and examples of venom PLAs with diminished catalytic activities are reviewed. Evolutionary strategies to reduce the venom PLA catalytic power and new function gains are discussed. Down-regulations of the enzymatic activities appear to be due to: 1) retention of interfacial binding, but with selective alternation of active site residues in basic PLAs; 2) mutations at both the interfacial binding sites and catalytic sites of strong anticoagulating PLAs which bind to the coagulation factor; and 3) either substitution or truncation of the interface binding sites in acidic subunits of heterodimeric PLA-neurotoxins to generate chaperon like molecules.