'Inverse' substrates for butyrylcholinesterase.

1. 'Inverse'-type substrates for butyrylcholinesterase (acylcholine acylhydrolase, EC 3.1.1.8), i.e., p- and o-nitrophenyl esters of (3-carboxypropyl)-trimethylammonium iodide, (4-carboxybutyl)trimethylammonium iodide and (5-carboxypentyl)trimethylammonium iodide were prepared, and their kinetic parameters for butyrylcholinesterase-catalyzed hydrolysis were determined. 2. The hydrolysis of these 'inverse'-type substrates were found to proceed through specific binding with the enzyme and efficient production of acyl enzyme intermediates, a pathway essentially identical with that followed by choline esters, normal type substrates.