A radioassay for pyrimidine-5'-nucleotidase activity.

A simple method for the determination of pyrimidine-5'-nucleotidase activity in red cells is described. The radioactive uridine released after incubation with [5-3H]] uridine 5-monophosphate (UMP) is separated on DEAE-cellulose paper and counted. This method does not require preliminary dialysis of the hemolysate and is 50-fold more sensitive than that based on the measurement of the inorganic phosphate released. One patient with pyrimidine-5'-nucleotidase deficiency was detected with this method.