Effect of α-Bungarotoxin on Acetylcholinesterase bound to Mouse Diaphragm Endplates

IT has been shown that α-bungarotoxin (α-Bgt) irreversibly blocks cholinoreceptors1-10, and that D-(+)tubocurarine (TC) protects these receptors from the toxin4-7. On the other hand, it has been emphasized that α-Bgt has no effect on the catalytic activity of acetylcholinesterase (AChE)4,6,9, and it was concluded that the cholinoreceptor and AChE must be two different macromolecules8,9. Because typical cholinolytics, including TC and gallamine, characteristically influence the kinetics of a membrane-bound AChE11,12, it seemed justified to reinvestigate whether α-Bgt really is an exception in this respect.