Positional specificity of lysosomal acid lipase purified from rabbit liver

The hydrolysis of tri-, di-, and monooleoylglycerols by highly purified lysosomal acid lipase from rabbit liver (Imanaka, T., et al. (1984) J. Biochem. 96, 1089-1101) was examined. The degradative products were separated by thin layer chromatography on silicic acid impregnated with boric acid. Trioleoylglycerol was hydrolyzed with intermediate accumulation of 1,2(2,3)-dioleoylglycerol and 2-monooleoylglycerol, but no detectable production of the 1,3-isomer. 1,2(2,3)-Dioleoylglycerol was also hydrolyzed with the intermediate accumulation of 2-monooleoylglycerol. The 1(3)-isomer of monooleoylglycerol was hydrolyzed exclusively, with no hydrolysis of the 2-isomer. These results indicate that the enzyme shows preference for 1(3)-ester bonds and that the main lipolytic reaction sequence catalyzed is triacylglycerol---1,2(2,3)-diacylglycerol---2-monoacylglycerol.