roup-Specific Assays That Distinguish between the Four ajor Types of Mammalian Phospholipase A 2

a t S a t g s Phospholipase A2 (PLA2) constitutes a diverse superamily of enzymes which catalyze the deacylation of hospholipids. At least four types of PLA2 are potentially nvolved in arachidonic acid release in cells and tissues. ince all of them catalyze the same enzymatic reaction, t is difficult to distinguish between them in mixtures of nzymes normally present in biological samples. Utilizng specific properties of each PLA2, we have designed istinct assay procedures which selectively and sensiively detect each type: Group VI Ca-independent LA2, Group IV cytosolic Ca-dependent PLA2, Groups and IIA secreted PLA2s. Each specific assay procedure s selective for a particular PLA2 type by at least fourfold nd as high as four orders of magnitude relative to the ther three enzymes. All assays can detect PLA2 activity ith as low as subnanogram quantities of enzyme. Imortantly, these assays are able to differentiate and uantitate the biochemically and structurally related nzymes, Group IIA and V sPLA2s in crude biological amples. Employing this system, we have found that PLA2 is the dominant PLA2 in rat brain, and cPLA2 is he most abundant PLA2 in P388D1 macrophages and uman amnionic WISH cells. © 1999 Academic Press