An asymmetric reactive site on electrophorus acetylcholinesterase

Lactoylcholine (LCh) is a racemic choline ester with an asymmetric carbon in the acid moiety. l(+)—LCh is hydrolyzed far more rapidly than d(−)—LCh by purified acetylcholinesterase from the electric organ of Electrophorus. At high substrate concentrations l(+) —LCh is also hydrolyzed more rapidly than acetylcholine but at approximately the same rate at low substrate concentrations. d(−)—LCh inhibits hydrolysis of l(+)—LCh. The existence of an asymmetric reactive site on the enzyme surface has been proposed to explain enzyme discrimination between the two isomers.