Figure 9.

Schematic representation of interfacial binding and catalytic action of sPLA2. (A) The binding of the sPLA2 at the lipid/water interface through the i-face is essential for catalysis. The enzyme passes along the horizontal plane on the bilayer, while hydrolyzing the phospholipid molecules and releasing the LPL and FA products [20]. (B) The minimal kinetic scheme for the catalytic cycle of sPLA2 is shown in a parallelogram box that represents the lipid bilayer. Here, E denotes enzyme in the aqueous phase, E* denotes enzyme in a membrane-bound state without substrate and K_d is the interfacial dissociation constant for the enzyme at the interface. K_S, K_cat and K_I are the dissociation constants for substrate, product and inhibitor, respectively. E*S and E*P denote the enzyme-bound substrate and enzyme-bound product, respectively. Adapted with permission from [20]. Copyright 2001, American Chemical Society.