The activity of phospholipase A2 in blood platelets of healthy donors and IHD patients was examined. The enzyme activity was found to be increased 3-fold in platelets possessing a high level of functional activity (IHD) and by one order of magnitude in patients with myocardial infarction as compared with healthy donors. An enzyme preparation possessing a phospholipase activity was isolated from platelets by using salt extraction (KCl) and sonication. Purification of the enzyme by affinity chromatography resulted in two protein peaks both having a phospholipase A2 activity, the purification and molecular masses of these fractions being 768- and 2200-fold, and 13.5 and 15 kDa, respectively. It was supposed that these proteins are substrate-specific forms of phospholipase A2.
