Two different activities of phospholipase A2 in porcine aortic cytosol

Two different activities of phospholipase A2 (PLA2s, EC 3.1.1.4) which was activated at micro molar concentration of free Ca2+ were identified in cytosolic fraction of porcine aortic tissue. The two enzymes behaved very similarly during purification on ion-exchange, hydrophobic, gel filtration and affinity columns, and finally the active peaks of these enzymes were separated from each other on a hydroxyapatite HPLC column. Both of the enzymes hydrolyzed efficiently phosphatidylcholine (PtdCho) containing arachidonoyl residue as the substrate, but showed the apparent differences in head group specificity of phospholipids and also in the sensitivity against high Ca2+ concentration. This is the first report for the identification and characterization of high molecular weight cytosolic PLA2s in porcine aortic tissue.