Most carbamates are pseudoirreversible inhibitors of cholinesterases. Phenothiazine carbamates exhibit this inhibition of acetylcholinesterase but produce reversible inhibition of butyrylcholinesterase, suggesting that they do not form a covalent bond with the catalytic serine. This atypical inhibition is attributable to π− π interaction of the phenothiazine moiety with F329 and Y332 in butyrylcholinesterase. These residues are in a helical segment, ...
