THE MODE OF ACTION OF PANCREATIC LIPASE ON MILK FAT GLYCERIDES

Abstract

Hydrolysis of tricaprylin by pancreatic lipase resulted in a stepwise hydrolysis, triglyceride to diglyceride to monoglyceride, as has been obtained with long-chain triglycerides. However, hydrolysis rates were much faster and considerable amounts of free glycerol were formed. Hydrolysis of an equimolar mixture of tricaprylin and triolein indicated that some of the short-chain fatty acid was released from the 2-position before all of the oleic acid was released from the 1-position. Hydrolysis of genuine and randomized milk fat resulted in preferential hydrolysis of glycerides containing short-chain fatty acids. This phenomenon was not dependent on a specific distribution of these acids, since it also occurred with the randomized fat. It was concluded that part of the short-chain fatty acids of milk fat is located in the 2-position. The distribution of caprylic and capric acids between the 1- and 2-positions is approximately at random. Lauric, myristic, and palmitic acids are predominantly located in the 2-position, and stearic and oleic acids in the 1-position, of milk fat glycerides.