Modulation of purified phospholipase A2 activity from human platelets by calcium and indomethacin.
A membrane bound phospholipase A2 (phosphatide 2-acylhydrolase, EC 3.1.1.4) from human platelets has been purified 3500-fold, and partially characterized. Phospholipase A2 activity was assayed using [1(-14)C] oleate-labeled Escherichia coli or sonicated dispersions of synthetic phospholipids. The 2-acyl specificity of the phospholipase activity was confirmed using phosphatidylethanolamine labeled in the C-1 position as substrate. The purified enzyme was maximally active between pH 8.0 and 10.5, and had an absolute requirement for low concentrations of Ca2+. Indomethacin, but not aspirin, inhibited phospholipase A2 activity.
D001792:Blood Platelets / Q000201:enzymology*; D002118:Calcium / Q000494:pharmacology*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007213:Indomethacin / Q000494:pharmacology*; D010740:Phospholipases / Q000097:blood*; D010741:Phospholipases A / Q000037:antagonists & inhibitors / Q000097:blood*; D054467:Phospholipases A2
D010740:Phospholipases; D010741:Phospholipases A; D054467:Phospholipases A2; D002118:Calcium; D007213:Indomethacin