Purification and characterization of rat liver microsomal monoacylglycerol lipase in comparison to the other esterases.

Monoacylglycerol lipase was separated from triacylglycerol lipase and two kinds of esterase in the microsomes by heparin treatment and DEAE-cellulose column chromatography. Monoacylglycerol lipase was purified about 1200-fold by DEAE-cellulose, hydroxylapatite, SP-Sephadex and Sephadex G-100 column chromatography from rat liver whole homogenate. The purified enzyme showed a single protein band by sodium dodecyl sul fate gel electrophoresis. The molecular weight was calculated to be approx. 62 000 by gel filtration on Sephadex G-200 and sodium dodecyl sulfate gel electrophoresis. The enzyme had an isoelectric point of 6.80 and pH optimum of 8.5. The enzyme maximally hydrolyzed long chain monoacylglycerol such as monomyristoylglycerol and hydrolyzed 1(3)- and 2-monoacylglycerol at equal rates and showed a little hydrolytic activity on short chain triacylglycerol such as tributyrylglycerol, but did not hydrolyze long chain triacylglycerol. The enzyme had different Km and V in comparison with the esterase fro various short chain triacylglycerols and long chain monoacylglycerols. Moreover, monoacylglycerol lipase differed immunologically from two kinds of microsomal esterase. Diisopropyl fluorophosphate inhibited the enzyme activity completely.