Identification and Characteristics of Acetylcholinesterase from Fish (Micropterus salmoides) Pectoral Muscles

Summary Acetylcholinesterase (EC 3.1.1.7) activity was investigated in bass pectoral fin muscle homogenates using a manometric technique. The enzyme was inhibited by excess substrate and had an optimum substrate concentration of 10 mM. Specific activity was 3.2 μmoles ACh hydrolyzed per mg protein/hr at 25°. The Michaelis constant and V max were 2.47 × 10-3 M and 4.56 μmoles ACh hydrolyzed per mg protein/hr, respectively. Specific AChE activity of the homogenates was inversely related to total wet wt of the fish with an R 2 of 0.68. Relative rates of hydrolysis for the choline esters studied were ACh > BuCh Ψ MeCh. Hydrolysis of BzCh was negligible. The inhibitors eserine, DFP and 284C51 gave pl50's of 6.75, 5.57 and 5.62, respectively.