An assay for adenyl cyclase based on a combination of sodium borate electrophoresis and paper chromatography

We describe a method for the assay of adenyl cyclase in whole tissue homogenates. Adenosine 3′:5′-cyclic monophosphate (cAMP) formed from α-32P-, 14C- or 3H-labeled adenosine 5′-triphosphate (ATP) substrate is isolated from all known ATP metabolites and an unknown metabolite by electrophoresis in 1% sodium borate for 40 min, followed by overnight descending chromatography in 95% ethanol:1 m ammonium acetate (70:30). The purity of the cAMP isolated is established by chromatographic techniques as well as by utilizing a purified cyclic nucleotide phosphodiesterase. The method described here also makes possible the measurement of phosphodiesterase activity in homogenates. It is rapid enough to allow routine assay of 180 samples per day, although the number of samples processed depends on the number of electrophoretic and chromatographic units available.