Structure and mechanism of human cytosolic phospholipase A2

cPLA2 is an 85-kDa enzyme whose primary function, the release of arachidonic acid from phospholipid membranes, is a crucial reaction in the metabolism of lipid mediators of inflammation. cPLA2 consists of two domains: an N-terminal, C2-type unit analogous to those present in other membrane-targeting molecules, and a catalytic domain harboring an active site dyad at the bottom of a deep, mostly hydrophobic catalytic funnel. The absence of a third active site residue in the cPLA2 cleft, as observed in other lipases, suggests that the enzyme proceeds through a novel catalytic mechanism. Crystallographic and biochemical studies of cPLA2 will provide essential information for the development of small molecule inhibitors which may be employed in the control of inflammatory and other highly regulated processes