[The effect of calmodulin and chlorpromazine on the activity of phospholipases A2 from various sources]

The effects of calmodulin and chlorpromazine on purified phospholipase A2 preparations from snake venoms: cobra (Naja naja oxiana), echis (Ehis multisquamatus) and Agkistrodon halys halys, as well as on phospholipases A2 from rat liver mitochondria and human platelets were studied. It was shown that within the concentration range of 1-5 microM calmodulin stimulates the phospholipase activity. Chlorpromazine inhibits the activity of these enzymes, the degree of inhibition being different for various phospholipases. Calmodulin was shown to interact with the phospholipases in the absence of exogenous Ca2+. The results obtained indicate that all phospholipases tested are calmodulin-dependent enzymes.