Partial purification and properties of diglyceride kinase from Escherichia coli

Diglyceride kinase (diacylglycerol kinase, E.C. 2.7.1.-), an enzyme localized in the inner membrane of Escherichia coli, has been purified about 600-fold. The purified enzyme exhibits an absolute requirement for magnesium ion; its activity toward both lipid and nucleotide substrates is stimulated by diphosphatidylglycerol or other phospholipids. Adenine nucleotides are much better substrates for the enzyme than are other purine or pyrimidine nucleotides. The purified enzyme preparation catalyzes the phosphorylation of a number of lipids, including ceramide and several ceramide and diacylglycerol-like analogs. The broad lipid substrate specificity of diglyceride kinase suggests that this enzyme may function in vivo for the phosphorylation of an acceptor other than diacylglycerol.