Pyrimidine nucleotidases from human erythrocyte possess phosphotransferase activities specific for pyrimidine nucleotides.
Two cytoplasmic forms of pyrimidine nucleotidase (PN-I and PN-II) have been purified from human erythrocytes to apparent homogeneity and partially characterized. They preferentially hydrolyse pyrimidine 5'-monophosphates and 3'-monophosphates respectively. PN-I and PN-II operate as interconverting activities, capable of transferring the phosphate from the pyrimidine nucleoside monophosphate donor(s) to various nucleoside acceptors, including important drugs like 3'-azido-3'-deoxy-thymidine (AZT), cytosine-beta-D-arabinofuranoside (AraC) and 5-fluoro-2'-deoxy-uridine (5FdUrd), pyrimidine analogues widely used in chemotherapy. Kinetic analysis showed linear behaviour for both PN-I and PN-II. PN-I phosphotransferase activity revealed higher affinity for oxynucleosides with respect to deoxy-nucleosides, whereas the contrary seems to be true for PN-II. These results show for the first time that soluble pyrimidine nucleotidases are endowed with pyrimidine-specific phosphotransferase activity.
Amici
A
A
Istituto di Biochimica, Facoltà di Medicina e Chirurgia, Università di Ancona, Italy.
Emanuelli
M
M
Magni
G
G
Raffaelli
N
N
Ruggieri
S
S
D004912:Erythrocytes / Q000201:enzymology*; D006801:Humans; D009708:Nucleotidases / Q000378:metabolism*; D010770:Phosphotransferases / Q000378:metabolism*; D011743:Pyrimidines / Q000378:metabolism
D011743:Pyrimidines; D010770:Phosphotransferases; D009708:Nucleotidases; C030986:pyrimidine