Photo-affinity labeling of specific acetylcholine-binding sites on membranes

Acetylcholinesterase of intact red blood cell membranes and the acetylcholine receptor at the neuromuscular junction of whole-frog sartorius muscle have been irreversibly inactivated by photo-affinity labeling with two quaternary ammonium aryl azides. The inactivation requires that the azides, at the time of their photolytic conversion to highly reactive nitrenes, are reversibly bound to the specific acetylcholine-binding sites.