title: Human cytidine deaminase: a biochemical characterization of its naturally occurring variants.
abstract: Human cytidine deaminase is an enzyme of the pyrimidine salvage pathways that metabolizes several cytosine nucleoside analogs used as prodrugs in chemotherapy. We carried out a characterization of the cytidine deaminase 79A>C and 208G>A Single Nucleotide Polymorphisms, in order to highlight their functional role and provide data that could help fine-tune the chemotherapic use of cytosine nucleosides in patients carrying the above mentioned SNPs. The 79A>C SNP results in a K27Q change in a protein region not involved in the catalytic event. The 208G>A SNP produces an alanine to threonine substitution (A70T) within the conserved catalytic domain. Q27 variant is endowed with a greater catalytic efficiency toward the natural substrates and the antileukemic agent cytarabine (Ara-C), when compared to K27 variant. Molecular modeling, protein stability experiments and site-directed mutagenesis suggest that K27 variant may have an increased stability with respect to Q27 due to an ionic interaction between a lysine residue at position 27 and a glutamate residue at position 24. The T70 variant has a lower catalytic efficiency toward the analyzed substrates when compared to the A70 variant, suggesting that patients carrying the 208G>A SNP may have a greater exposure to cytosine based pro drugs, with possible toxicity consequences.
authors.affiliation: School of Biosciences and Biotechnology, University of Camerino, via Gentile III da Varano, 62032 Camerino, MC, Italy.
authors.forename: Daniela
authors.initials: D
authors.lastname: Micozzi
authors.affiliation: School of Biosciences and Biotechnology, University of Camerino, via Gentile III da Varano, 62032 Camerino, MC, Italy.
authors.forename: Francesco Martino
authors.initials: FM
authors.lastname: Carpi
authors.affiliation: School of Biosciences and Biotechnology, University of Camerino, via Gentile III da Varano, 62032 Camerino, MC, Italy.
authors.forename: Stefania
authors.initials: S
authors.lastname: Pucciarelli
authors.affiliation: School of Biosciences and Biotechnology, University of Camerino, via Gentile III da Varano, 62032 Camerino, MC, Italy.
authors.forename: Valeria
authors.initials: V
authors.lastname: Polzonetti
authors.affiliation: School of Pharmacy, University of Camerino, via circonvallazione 93/95, 62024 Matelica, MC, Italy.
authors.forename: Paolo
authors.initials: P
authors.lastname: Polidori
authors.affiliation: Department of Organic Chemistry, Faculty of Pharmacy, University of Santiago de Compostela, Santiago de Compostela 15782, Spain.
authors.forename: Santiago
authors.initials: S
authors.lastname: Vilar
authors.affiliation: Department of Chemistry, American University, Washington, DC 20016, USA.
authors.forename: Brian
authors.initials: B
authors.lastname: Williams
authors.affiliation: Department of Chemistry, American University, Washington, DC 20016, USA. Electronic address: costanzi@american.edu.
authors.forename: Stefano
authors.initials: S
authors.lastname: Costanzi
authors.affiliation: School of Veterinary Medical Sciences, University of Camerino, via circonvallazione 93/95, 62024 Matelica, MC, Italy. Electronic address: silvia.vincenzetti@unicam.it.
authors.forename: Silvia
authors.initials: S
authors.lastname: Vincenzetti
mesh_terms: D000970:Antineoplastic Agents / Q000008:administration & dosage*; D002384:Catalysis; D003561:Cytarabine / Q000008:administration & dosage; D003564:Cytidine Deaminase / Q000737:chemistry / Q000235:genetics*; D006801:Humans; D007700:Kinetics; D007938:Leukemia / Q000188:drug therapy* / Q000201:enzymology / Q000473:pathology; D016297:Mutagenesis, Site-Directed; D020641:Polymorphism, Single Nucleotide / Q000235:genetics*
chemical_list: D000970:Antineoplastic Agents; D003561:Cytarabine; D003564:Cytidine Deaminase
keywords: 1-β-d-arabino furanosylcytosine or cytarabine; 1-β-d-arabinofuranosyl-5-azacytosine; 2′,2′-difluorodeoxycytidine or gemcitabine; 2′,3′-CdR; 2′,3′-dideoxycytidine; 2′-deoxycytidine; 5′-azadeoxycytidine; 6-aza-CR; 6-azacytidine; Ara-C; Aza-CdR; CDA; CR; CdR; Cytidine deaminase; DTT; EDTA; Genetic polymorphism; IPTG; Kinetic analysis; Molecular modeling; SNP; Single Nucleotide Polymorphisms; Site-directed mutagenesis; THU; cytidine; cytidine deaminase; dFdC; dithiothreitol dithiothreitol; ethylenediaminetetraacetic acid; fazarabine; isopropyl-thio-β-d-galactopyranoside; tetrahydrouridine