A Membrane-bound Pyrophosphatase in Escherichia coli Catalyzing the Hydrolysis of Cytidine Diphosphate-Diglyceride

An enzyme discovered in the cell membrane fraction of Escherichia coli catalyzes the following reaction: CDP-diglyceride + H2O → CMP + phosphatidic acid The enzyme has been extracted from the membrane fraction with the nonionic detergent Triton X-100 and has been purified 115-fold. This novel hydrolase appears to have a high specificity, since it does not attack at a significant rate DPN, ATP, or CDP-choline, substrates that are rapidly split by nucleotide pyrophosphatase(s) of broad specificity previously described in plant and animal tissues. It also appears to be distinct from the periplasmic bacterial hydrolases specific for nucleoside diphosphate sugars. The CDP-diglyceride hydrolase is devoid of phospholipase D activity and is also unusual in that it is strongly inhibited by AMP.