An improved method for the determination of human erythrocyte pyrimidine 5′-nucleotidase activity

A radiometric method is described for measuring pyrimidine 5′-nucleotidase activity in human peripheral blood haemolysate. The substrate [ 14C]uridine monophosphate is converted to [ 14C]uridine. Two simple and rapid methods to isolate the product of the reaction employing either descending chromatography or elution from DEAE cellulose paper have been developed. With the described methods the specific activity of pyrimidine 5′-nucleotidase of human erythrocytes is 6.7 ± 2.7 (± 1 S.D.) nmol/h/mg protein and this activity appears to be widely distributed in human tissue.