Human erythrocyte pyrimidine 5'-nucleotidase, PN-I.
Erythrocyte maturation is accompanied by RNA degradation and release of mononucleotides. Pyrimidine 5'-nucleotidase, PN-I, has been purified and characterized. The molecular and enzymatic properties determined for the enzyme shows a 36-kDa and 5.1 pI monomeric protein with no disulfide bridges and no phosphate content. The activity is dependent on Mg(2+), while it is inactivated by heavy metals and by thiol-reactive reagents. PN-I is specific for pyrimidine nucleoside monophosphates, including the antineoplastic agents 5'-AZTMP and 5'-Ara-CMP. PN-I possess phosphotransferase activity able to exchange phosphate between pyrimidine nucleoside monophosphates and pyrimidine nucleosides, including AZT and Ara-Cyd. Amino acid sequence has been obtained from tryptic and CNBr peptides. PN-I cDNA sequence, coding for a 286-residue protein, has been retrieved from tag database, amplified by PCR, and expressed in Escherichia coli. The recombinant protein was fully active and showed identical properties with respect to PN-I. Substantial identity has been revealed with the partial sequences reported for p36, an alpha-interferon-induced protein. The significance of this identity is discussed.
Amici
Adolfo
A
Istituto di Biochimica, Facoltà di Medicina e Chirurgia, Università di Ancona, Via Ranieri 65, Ancona, 60131, Italy. amicia@popcsi.unian.it
Magni
Giulio
G
D015720:5'-Nucleotidase / Q000378:metabolism*; D000595:Amino Acid Sequence; D001483:Base Sequence; D004912:Erythrocytes / Q000201:enzymology*; D006801:Humans; D007700:Kinetics; D008969:Molecular Sequence Data; D010770:Phosphotransferases / Q000378:metabolism; D013379:Substrate Specificity
D010770:Phosphotransferases; D015720:5'-Nucleotidase