Choliae esterases and choline acetyltransferase in the seeds ofAllium altaicum (Pall.) Reyse

In the seeds ofAllium altaicun (Pall.)Reyse a set of enzymes was found, metabolizing choline esters, composed of active choline esterases and choline acetyltransferase. Choline esterase cleaving acetylcholine occurs in five isoenzymes. The enzyme preparation hydrolyses strongly acetylthiocholine and sinapine, but weakly butyrylthiocholine (20%) in comparison with acetylthiocholine. The hydrolysis of the substrates mentioned is inhibited by physostigmine and neostigmine, but it is not inhibited by the specific inhibitor of acetylcholine esterase (BW 284 C51). In addition to hydrolytic activity a strong catalytic activity of choline acetyltransferase was also observed during the synthesis of sinapine from sinapic acid and choline. The detection of the mentioned enzymes in some representatives of theAllium genus indicates that choline esterases are more widely distributed in monocotyledons than previously assumed.