Species difference and characterization of intestinal esterase on the hydrolizing activity of ester-type drugs.

The ability of the esterase from intestine was studied for hydrolysis of ester-type drugs during absorption. The intestinal esterase is present in the absorption sites in the intestine and hydrolyzes to a large extent during the absorption. In a study of the dietary effect on intestinal esterase, the esterase activity increased in rats fed a high-fat diet, decreased in those fasted or fed a fat-free diet, whereas the esterase activity in the rat treated with phenobarbital showed no marked change. Thus the esterase from intestinal mucosa appears to be characteristically quite different from hepatic esterase. The esterase from human intestine was characterized and compared with esterase from rats, mice, rabbits, guinea pigs and dogs. There was a difference in the substrate specificity of the esterase and there were significant species differences in the electrophoretic behavior of the enzyme among the species tested. These results indicate that intestinal esterase from humans differs characteristically from esterases in experimental animals.