Hydrolysis of synthetic mixed-acid phosphatides by phospholipase A from human pancreas

Abstract

An investigation was made into the action of a human pancreatic phospholipase A on various synthetic phosphatides. L-α-Phosphatidyl ethanolamines were readily hydrolysed in an aqueous system by this enzyme. Synthetic lecithins, however, were not attacked in an appreciable rate by the mammalian phospholipase A, contrary to the action of the enzymes from animal poisons. Addition of deoxycholate1 or synthetic phosphatidic acid greatly enhanced the degradation of synthetic lecithins by the pancreatic phospholipase A.

The site of action of the human pancreatic phospholipase A was determined with the aid of mixed-acid lecithins and phosphatidyl ethanolamines containing in different molecular positions combinations of stearic and lauric acid, stearic and oleic acid, palmitic and linolenic acid, respectively. The enzyme was demonstrated to liberate always the β-esterified fatty acids while the γ-attached fatty acid constituents were recovered in the produced lyso compounds. Hence the mode of action of this phospholipase A from human pancreas is identical to the action of the corresponding phospholipase from animal poisons so far investigated.