Jan 1, 1976

beta-Bungarotoxin, a pre-synaptic toxin with enzymatic activity

Proceedings of the National Academy of Sciences of the United States of America
P N StrongR B Kelly

Abstract

beta-Bungarotoxin, a pre-synaptic neurotoxin isolated from the venom of the snake Bungarus multicinctus, has been shown to modify release of neurotransmitter at the neuromuscular junction. In this communication, we demonstrate that beta-bungarotoxin is a potent phospholipase A2 (phosphatide 2-acyl hydrolase, EC 3.1.1.4), comparable in activity with purified phospholipase enzymes from Naja naja and Vipera russellii. The phospholipase activity of beta-bungarotoxin requires calcium and is stimulated by deoxycholate. When strontium replaces calcium, no phospholipase activity is detected. Since neuromuscular transmission is not blocked when calcium is replaced by strontium, it was possible to examine the effects of the toxin on neuromuscular transmission in the presence of strontium. Under these conditions, when the phospholipase activity should be inhibited, the toxin has little or no effect on neuromuscular transmission. If beta-bungarotoxin owes its toxicity in part to its enzymatic activity, then it must be placed in a different class from those toxins which produce their effect by binding passively to an appropriate receptor.

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References

Mentioned in this Paper

Calcium [EPC]
PLA2G2A protein, human
Phospholipase A2, human
Enzymes, antithrombotic
Calcium
Toxin
PLA2G4C protein, human
Synapses
Enzymes for Treatment of Wounds and Ulcers
Neurotransmitters

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