Lecithinase and lysolecithinase of intestinal mucosa.

Enzymes, capable of hydrolysing lecithin to liberate inorganic phosphate, are present in the kidney and intestinal mucosa (King, 1931). Since several pathways may lead from lecithin to inorganic phosphate and more than a single bnzyme must have been involved, it is uncertain which enzyme was the rate-limiting one in this investigation. In a recent paper Schmidt, Bessman & Thannhauser (1957) described a mitochondrial preparation of rat intestinal mucosa, which catalysed the splitting of fatty acids from kephalin. Some activity, though a much smaller one, was found with lecithin as substrate. The low activity of similar intestinalmucosa preparations towards lecithin was attributed by us, in a preliminary communication (Epstein & Shapiro, 1957), to the fact that lecithin degradation by the intestinal enzyme depends upon the presence of fatty acids. This activation by one of its reaction products puts the enzyme involved into a category apart from other lecithinases. As will be seen in the present paper, intestinal lecithinase differs from known lecithinases in several other respects.