Partial purification and properties of monoacylglycerol lipase and two esterases from isolated rat small intestinal epithelial cells.

In intestinal epithelial cells, three enzymes possessing monoacylglycerol hydrolase activity were found and partially purified. Two of these enzymes have properties that justify their classification as an esterase and one as a monoacylglycerol lipase. The three enzymes show similar Km values for monooleoylglycerol and each shows similar activity towards 1- and 2-monopalmitoylglycerol. Antiserum raised in rabbits against rat liver monoacylglycerol lipase inhibits the intestinal lipase completely, suggesting that the enzymes are at least partially similar. The esterases of small intestinal villus cells were not inhibited by the antiserum against liver monoacylglycerol lipase. It was calculated that the esterases account for approx. 2/3 of the monooleoylglycerol hydrolase activity in epithelial cells. Monoacylglycerol lipase also hydrolyzed palmitoyl-CoA, while the esterases did not. The enzymes were inhibited by micellar palmitoyl-CoA. The hypothesis that palmitoyl-CoA is an important regulator for monoacylglycerol acylation is discussed in the light of these new findings.