Lecithinase Activity in the Muscle of Rainbow Trout (Salmo gairdnerii)

Abstract

A radioactive tracer procedure for determination of the various lecithin hydrolysing enzymes, at a low level of activity, is described. The procedure involves the use of phospholipids labeled with C14in the choline moiety as substrate and the measurement of radioactivity released in the various products of hydrolysis. The pathway of lecithin catabolism in trout muscle is via glycerylphosphorylcholine. Of the other possible routes of breakdown of lecithin, there was no indication for the activity of phospholipase C or D. Greater enzymic activity was present in the lateral line muscle than in the white muscle. The enzyme which is responsible for hydrolysis of lecithin to glycerylphosphorylcholine showed optimum activity in the vicinity of pH 7 did not require Ca++for activity and was partially inhibited by Hg++. A lysolecithinase, showing similar properties, but having a comparatively greater activity, was also present in trout muscle.