Monoglyceride-hydrolyzing activity of rat myocardium

Abstract

A study of lipases in rat myocardium confirmed the presence of an enzyme differing from lipo-protein lipase. The enzyme was optimally active at pH 6.8 and did not require serum proteins for activity. Unlike lipoprotein lipase, this activity was not inhibited by NaCl or protamine sulfate, but was inhibited by NaF. Monoolein and monostearin were rapidly hydrolyzed by the enzyme, whereas tripalmitin was hydrolyzed only very slowly. The enzyme thus seems to attack preferentially mono-glycerides. The enzyme was inhibited by diisopropylfluorophosphate and N -ethylmaleimide. From these, and other properties, the cardiac enzyme is clearly similar to monoglyceride-hydrolyzing lipases from adipose tissue and intestinal mucosa.