Hydrolysis of chylomicron retinyl esters by an acid hydrolase of rat liver.

Rat liver homogenate hydrolyzed chylomicron remnant retinyl esters with pH optima 4.5, 6 and 8. The retinyl ester hydrolysis at pH 4.5 was correlated to the acid phosphatase activity in different subcellular fractions, and thus the highest activity was found in highly purified lysosomes. These fractions could also catalyze the reverse reaction, i.e., the esterification of retinol when incubated with excess palmitic acid. Purified rat liver lysosomes hydrolyzed chylomicron retinyl and cholesteryl esters with comparable rates, both being much lower than the hydrolysis of chylomicron triacylglycerols.