Studies on the specificity of CNF, a phospholipase A2 inhibitor isolated from the blood plasma of the South American rattlesnake (Crotalus durissus terrificus).: I.: Interaction with PLA2 from Lachesis muta muta snake venom

A phospholipase A(2) inhibitor has been previously purified and cloned from the blood plasma of the South American rattlesnake, Crotalus durissus terrificus. This inhibitor, named CNF for Crotahus neutralizing factor, interacts with crotoxin, the main neurotoxin from C. d. terrificus venom, abolishing its phospholipase A(2) activity. Crotoxin is a heterodimer of an acidic subunit (CA) and a basic phospholipase A(2) (CB). CNF acts by forming a stable non-toxic complex with CB, replacing CA in the toxic CA-CB of crotoxin. In the present investigation, we have shown that CNF has a broader specificity. It is able to inhibit the PLA(2) activity of the whole venom from the bushmaster snake (Lachesis muta muta), a species evolutionary related to Crotalus. Inhibition experiments have been carried out with four PLA(2) active components isolated from L. m. muta venom, one basic and three acidic ones. CNF inhibition is not restricted to the basic PLA(2), but extended to the three acidic forms as well. (C) 1999 Elsevier Science Ltd. All rights reserved.