Snake Venom Neurotoxins Related to Phospholipase A2

Abstract

Two types of highly lethal toxins have been isolated from certain crotalids, elapids, vipers, and seasnakes that act by blocking peripheral neuromuscular impulse transmission and cause death by respiratory paralysis. One type acts postsynaptically by binding to the acetylcholine receptors, contains proteins of 61—74 amino acids, has been intensively studied, and will not be discussed here. The other type consists of proteins that are at least twice as large and are all related to and presumably derived from phospholipase A2. The four most studied of this group are crotoxin, β-bungarotoxin, notexin and taipoxin from the Brazilian rattlesnake, the Formosan krait and the Australian tigersnake and taipan, respectively. Their structures and modes of actions, largely presynaptic and complex, represent the subject matter of this review.