Selective precipitation of 32Pi onto filter papers. Application to ATPase and cyclic AMP phosphodiesterase determination.

A simple and selective method is described for the isolation of 32Pi based on the precipitation of the phosphomolybdate complex with triethylamine. Precipitation takes place on filter paper, which are then washed with a solution containing ammonium molybdate and triethylamine to remove other radioactive phosphates. Very large numbers of samples and very small sample volumes can be accommodated easily. The use of this method to measure ATPase and cyclic AMP phosphodiesterase activity is demonstrated.