HYDROLYSIS OF GLYCEROLPHOSPHATIDES BY PLASTID PHOSPHATIDASE C

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Abstract
Studies of the influence of structural variation in the glycerol-phos-phatide molecule on the hydrolysis of this class of compounds by plastid phosphatidase C showed that the presence of both fatty acid ester groups is necessary for enzymatic reaction. In the presence of ethyl ether, release of nitrogenous bases occurred from phosphatidyl choline, phosphatidyl ethanolamine, and phosphatidyl serine. Phosphatidyl choline was hydrolyzed more rapidly than the corresponding phosphatidyl ethanolamine or phosphatidyl serine. The rate of hydrolysis of phosphatidyl choline was influenced greatly by the chain length and degree of unsaturation of the fatty acids. The corresponding phosphatidic acid, formed in the hydrolysis of (dipalmitoyl) - or (di-palmitoleyl)-lecithin by carrot phosphatidase C, was isolated. Studies on the hydrolysis of crude soybean phosphatide by phosphatidase C showed that both choline and ethanolamine were liberated in the absence of ethyl ether, at an optimum pH of 4.8; in the presence of ether, the rate of liberation of each base was increased, and the pH optimum was between 4.8 and 6. Soybean phosphatide probably contains a substance that stimulates the enzymatic hydrolysis.