Relationship between the neurotoxicity and phospholipase A activity of beta-bungarotoxin.
beta-Bungarotoxin is a protein neurotoxin that exhibits phospholipase A activity. The neurotoxin and phospholipase A activities were similarly affected by several agents that modify proteins in various ways. Both activities were very thermostable and resistant to treatment with proteases, 6 M urea, phenylmethylsulfonyl fluoride, and N-acetylimidazole. Both activities were sensitive to beta-mercaptoethanol, and to N-bromosuccinimide and ethoxyformic anhydride, which previously had been shown to inactivate rattlesnake venom phospholipase A by modifying selective amino acids. Dihexanoyllecithin, which acts as a substrate for the beta-bungarotoxin phospholipase A, and Ca2+ protect the phospholipase A activity against inactivation by ethoxyformic anhydride but not the neurotoxicity. Treatment of intact membranes with proteases reduces hydrolysis of the membranes lipids by the toxin phospholipase A.
D000818:Animals; D001681:Biological Assay; D002038:Bungarotoxins / Q000378:metabolism / Q000633:toxicity*; D007700:Kinetics; D051379:Mice; D010713:Phosphatidylcholines; D010740:Phospholipases / Q000378:metabolism*; D014361:Trypsin Inhibitors / Q000494:pharmacology
D002038:Bungarotoxins; D010713:Phosphatidylcholines; D014361:Trypsin Inhibitors; D010740:Phospholipases