Effect of Phospholipid Hydrolysis on Lipid Oxidation in Flounder Muscle Microsomes

Abstract

ABSTRACT Endogenous phospholipase A activity was observed to be associated with the microsomal fraction of flounder muscle. Preincubation of microsomes with exogenous phospholipase A 2 resulted in an inhibition of both enzymic and nonenzymic lipid oxidation systems contrary to the generally accepted assumption that fatty acids are more susceptible to oxidation when free than when esterified. Removal of free fatty acids from the membrane led to a partial restoration of oxidative activity in both systems. Preincubation of microsomes with phospholipase C lowered enzymic oxidation but did not affect non‐enzymic oxidation, whereas, preincubation with 1% sodium desoxycholate led to inhibition of both oxidation systems. This study suggests a direct role of phospholipid hydrolysis in the inhibition of lipid oxidation in an isolated membrane fraction of fish muscle and the possibility that such hydrolysis in situ may be a controlling factor in lipid oxidation and its subsequent effects.