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Human Erythrocyte Pyrimidine 5'-nucleotidase, PN-I
No full textErythrocyte 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 Mg2+, while it is inactivated by heavy metals and by thiol-reactive reagents. PN-I is specific for pyrimidine nucleoside monophosphates, including the anineoplastic 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 aicd sequence has been obtained from tryptic and CNBr peptides. PM cDNA sequence, coding for a 286-residue protein, has been retrived 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. (C) 2002 Elsevier Science
Nucleotide metabolism in human erythrocytes: purification and properties of a specific pyrimidine 5'-nucleotidase
No full textThe Enzymology of Cytosolic Pyrimidine 5'-Nucleotidases: Functional Analysis and Physiopathological Implications.
No full textIn mammals, cellular 5'-nucleotidase (5'-NT) activity (EC 3.1.3.5) encompasses a number of genetically and structurally distinct enzyme forms, either membrane-bound or soluble, mainly cytosolic, that are characterized by broad specificity towards nucleoside 5'-monophosphate substrates differing in base (purine/pyrimidine) and/or sugar (oxy/deoxy-ribose) moieties. In particular, among the cytosolic 5'-NTs active towards pyrimidine nucleotides are cN-III and cdN, ubiquitously distributed in mammalian tissues and treated as a single entity in the early days. cN-III was first linked to a genetic defect, hereditary pyrimidine nucleotidase deficiency, associated to a nonspherocytic hemolytic anemia disorder of still unclear mechanism but metabolically characterized by abnormally high levels of pyrimidine compounds and ribonucleoproteins in erythrocytes, as evidenced by occurrence of basophilic stippling on blood smearings. Since the first review on pyrimidine-specific nucleotidases (Amici, A.; Magni, G., Arch. Biochem. Biophys., 2002, 397(2), 184-190), excellent overviews on the topic appeared in the literature. In the present contribution, the major findings on these two enzymatic proteins, cN-III and cdN, will be described with particular emphasis on the relationships between their structure and function, as well as on their roles in normal and pathological conditions. The catalytic mechanism of both specific hydrolytic and phosphotransferase activities, possessed by both enzymes, will be discussed also in the light of recent solution of both cN-III and cdN three-dimensional structures. This review also focuses on possible therapeutic approaches involving cellular 5'-NTs in detoxifying common antiviral and antineoplastic drugs
Induction studies on enzymes involved in the metabolism of pyrimidine nucleosides in E.coli B.
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Purification, microsequencing, cloning and expression of human erythrocytes pyrimidine 5'-nucleotidase (PNI) and its identification as p36 interferon-induced protein.
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Identification of the gene encoding nicotinamide mononucleotide deaminase: "a missing" enzyme in eubacterial NAD(P) biosynthesis
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