Lecithinase and lysolecithinase of intestinal mucosa

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Abstract
A particulate enzyme system which decomposes lecithin and lysolecithin into glycerylphosphorylcholine and fatty acids was isolated from the mucosa of rat intestines. Lecithin breakdown was dependent upon the presence of fatty acids. The optimum concentration of fatty acids depends upon the concentration of the substrate and is roughly equimolar to it. With suboptimum concentrations (e.g. with the endogenous fatty acids present in the enzyme preparation) the reaction is autocatalytic, starting with a lag period. This lag period can be prolonged to more than 24 hours by removing most of the endogenous fatty acids from the enzyme by washing it with serum albumin solution. Linoleic and oleic acid were the most efficient activators found, followed by lauric and decanoic acid of the saturated acid series. Tween 80, cholic acid and saponin could not replace fatty acids. Ca 2+ ion was not required for activity and was inhibitory at a concentration of 5mM. Other bivalent cations, especially Hg2+ andCd2+ ions, were also strongly inhibitory. Lecithin-ase and lysolecithinase action had a pH optimum at 6.5 which was also the point of greatest stability. The enzyme was inactivated by short incubations at 30-50[degree] but lecithin gave some protection. Activity with lysolecithin was always greater than with lecithin and no fatty acids were required for breakdown of the former compound.

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