An improved method for assaying pyrophosphate exchange measuring Cerenkov radiation

The determination of the amount of radioactivity in ³²P-labeled nucleotides absorbed to charcoal is greatly simplified when the same medium is used for extraction and for counting the secondary Cerenkov radiation. Addition of 4-methylumbelliferone increases the efficiency and decreases quenching caused by charcoal particles. With regard to reproducibility and amount of background the method is comparable to other published methods. Its application in a pyrophosphate exchange assay is described.