Hydrolysis of phospholipids by a lysosomal enzyme.

The phospholipid-hydrolyzing activity of rat liver lysosomes has been studied. These lysosomes contain a phospholipase that cleaves both fatty acid ester linkages of lecithin and of phosphatidyl ethanolamine and releases free fatty acids from both positional isomers of lysolecithin. The enzyme does not require calcium for maximum activity, and is inhibited by diethyl ether and sodium deoxycholate.

Quinones and quinols as inhibitors of lipid peroxidation.

The influence of biological quinonoid compounds upon oxidative polymerization of lipids has been compared with that of simple quinones and antioxidants. A new procedure for the accelerated production and measurement of oxidative polymerization was used for this comparison. The biological quinones were found to be relatively ineffective as retarders of oxidative polymerization.

RAT-KIDNEY LYSOSOMES: ISOLATION AND PROPERTIES.

1. The activities of lysosomal enzymes in the cortexes and medullas and the principal subcellular fractions of rat kidney were measured. 2.

Studies on the release of lysosomal enzymes from kidney lysosomes.

Incubation of kidney lysosomes at 37 degrees results in a graded release of lysosomal enzymes. The release of enzyme occurs in two stages. First the enzymes become available to the substrate but remain sedimentable.

LYSOSOMAL ENZYMES OF RAT INTESTINAL MUCOSA.

Six intracellular hydrolases known to be associated with lysosomes in rat liver were found in rat intestinal mucosa. The extent to which they were particulate-bound and the degree of enzyme release when the particulate fractions were suspended in hypotonic media followed the same pattern in both mucosa and liver. The specific activities of the mucosa enzymes were either comparable to or slightly smaller than those of the liver enzymes.