3-Trimethylaminomethyl catechol (TMC) was synthesized and shown maximally to inactivate 50% of the α-bungarotoxin (B tx) binding to the acetylcholine receptor (AcChR) from Torpedo californica electroplax. Incubation of the receptor with unsubstituted catechol produced no toxin binding inactivation of the receptor. Further, co-incubation of the receptor with 1 mM hexamethonium and 30 mM TMC effectively blocked the affinity-directed inactivation of Btx binding produced by incubation with 30 mM TMC alone. This degree of protection was consistent with the relative binding constants for hexamethonium (4.8 × 10-6 M) and TMC (2.8 × 10-5 M) with the AcChR. The affinity directed inactivation is suggested to be due to the covalent reaction of one or more of the quinone intermediates formed during the spontaneous oxidation of TMC with the Btx binding sites of the AcChR.
|Number of pages
|Biochemical and Biophysical Research Communications
|Published - Aug 31 1982