Radioisotopic assay for erythrocyte adenosine 5'-monophosphate deaminase

Adenosine-5'-monophosphate deaminase is a critical enzyme in the regulation of adenine nucleotide levels in the erythrocyte. The routine examination of this enzyme in crude hemolysates is difficult with the commonly used assay which monitors ammonia generated by the deamination reaction. This report details a radioisotopic assay for AMP deaminase which allows separation of the [14C]inosine 5'-monophosphate product from the [14C]adenosine 5'-monophosphate substrate by ion-exchange chromatography at pH 2.2. The radioisotopic assay is linear with respect to time and enzyme concentration over a considerable range and thereby significantly simplifies the monitoring of crude or dilute enzyme preparations.