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Abstract Transphosphatidylase activity was recognized in several plant tissues as well as in extracts. It was attributed to phospholipase D. This enzyme was purified 110-fold from Savoy cabbage. The ratio of its hydrolase to its transphosphatidylase activity remained constant throughout the purification. Additional evidence supports the conclusion that both reactions are catalyzed by the same enzyme. Phosphatidylations of ethanol, ethanolamine, and glycerol were readily achieved by incubating phosphatidylcholine and the enzyme in the presence of one of these acceptors. Concentrations of the acceptors required for equality between rates of hydrolysis and transphosphatidylation were 0.7, 0.3, and 1.1%, respectively, for ethanol, ethanolamine, and glycerol. The glycerol configuration in the phosphatidylglycerol thus produced was dl-; phosphatidylation in this case was not stereospecific. Phospholipase D catalyzed exchange between choline and phosphatidylcholine. Its activity was completely inhibited in 10-4 m p-chloromercuribenzoate. The results implicate formation of a phosphothioester linkage in the phosphatidylenzyme complex. The transphosphatidylase function of phospholipase D offers a useful route for synthesis of a variety of phosphatidyl esters.
Yang et al. (Wed,) studied this question.