Intracellular Localization of ATP:AMP Phosphotransferase in Escherichia Coli

ATP and AMP were immediately converted into ADP by intact cells of Escherichia coli in the presence of Mg2+, while ADP was also rapidly converted into ATP and AMP under the same conditions. Adenylate kinase was released when E. coli cells were converted to spheroplasts by treatment with lysozyme-EDTA or osmotic shock. Adenylate kinase activities detected in the cytoplasm, periplasm and membrane fractions were approximately 58%, 36% and 6% of the total cellular activity, respectively. These results indicate that adenylate kinase in E. coli occurs in the periplasm as well as the cytoplasm.