A LECITHINASE A IN DUODENAL CONTENTS OF MAN.

Lecithinase A catalyzes the removal of a fatty acid from lecithin or the cephalins to yield lysolecithin or the lysocephalins which are particularly noted for their lytic effect on red blood cells (1). Hanahan (2) studied the action of the enzyme in extracts of pancreatin on lecithin in diethyl ether. This method was used by Hanahan, Rodbell and Turner (3) and improved by Long and Penny (4) in studies of the action of the enzyme in venom on natural and synthetic phosphoglycerides. Epstein and Shapiro (5) and Rimon and Shapiro (6) measured the enzyme from rat intestinal mucosa and ox pancreas in phosphate buffer. Borgstr6m's (7) report of the almost complete conversion of lecithin in bile to lysolecithin in the upper small intestine of man prompted us to undertake the measurement of the enzyme involved. A simplified assay was evolved using the fasting duodenal contents of man as the source of enzyme. The release of fatty acids from lecithin was measured titrimetrically. The concurrent decrease in lecithin and equivalent increase in lysolecithin were measured by quantitative chromatography using silicic acid impregnated paper (8, 9). Some factors which increase or decrease the sensitivity of the assay were also evaluated.

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