Measurements of rates of adenosine 3':5'-cyclic monophosphate synthesis in intact Escherichia coli B.

A method for labeling adenosine 3':5'-cyclic monophosphate in vivo from precursor adenosine followed by quantitative analysis of the labeled nucleotide is described. When the labeling period is short and the specific activity of the ATP pool is determined, the rate of incorporation of radioactivity corresponds to a determination of adenylate cyclase activity in vivo. In E. coli B the specific activity of adenylate cyclase in vivo varies under different growth conditions. Under all conditions tested, the adenylate cyclase activity in vivo is great enough to account for the pattern of accumulation of cyclic AMP. This is in contrast to previous adenylate cyclase assays in vitro, where the measured enzyme activities were insufficient to account for the amounts of cyclic AMP accumulated.