Comparison of three phospholipases isolated from copperhead venoms

Abstract 1. 1. Three phospholipases were purified by molecular sieve chromatography from ion-exchange fractions obtained from whole copperhead snake ( Agkistrodon contortrix ) venoms. 2. 2. In comparing the three phospholipases, one acidic and two basic, all had molecular weights of 16,500–20,500, temperature optima of 60–70°C, and basic pH optima, but only the acidic enzyme was significantly heat stable at a pH of 6.5. This latter enzyme was the only one which was inactive in diethyl ether. All three enzymes appeared to be phospholipase A 2 's. 3. 3. The two basic enzymes caused the hemolysis of human red blood cells if lecithin was present. The inclusion of EDTA † abolished this activity.