Pyrimidine nucleotidases phosphotransferases from human erythrocyte

Two cytoplasmic pyrimidine 5'-nucleotidase have been purified from human er ythrocytes to homogeneity and partially characterized. The two enzymes, ind icated as PN-I and PN-II, preferentially hydrolyse pyrimidine 5'-monophosph ates and 3'-monophosphates, respectively. The kinetic analysis demonstrate that pyrimidine 5'-nucleotidases, in the presence of suitable nucleoside su bstrates, can operate as phosphotransferases by transferring phosphate to v arious nucleoside accepters, including nucleoside analogues known as import ant drugs widely used in chemotherapy.