title: Site directed mutagenesis as a tool to understand the catalytic mechanism of human cytidine deaminase.
abstract: Cytidine deaminase (CDA), is one of the enzymes involved in the pyrimidine salvage pathways, which catalyzes the formation of uridine and deoxyuridine by the hydrolytic deamination of cytidine and deoxycytidine, respectively. Human CDA is a tetrameric enzyme of identical 15 kDa subunits, each containing an essential zinc atom in the active site. The substrate binds to each active site independently and the cooperativity between subunits has not been reported. CDA is able to recognize as substrates some antitumor and antiviral cytidine analogs rendering them pharmacologically inactive. In light of the role played by this enzyme, a deep knowledge of CDA active site and mechanism of catalysis is required. Site-directed mutagenesis, associated with molecular modeling studies, may be an important tool to discover the active site structure of an enzyme and consequently its mechanism of action. In this review are summarized the site-directed mutagenesis experiments performed on human CDA: through these studies it was possible to understand the role exerted by specific amino acid residues in CDA active site and in the contacts between subunits. The obtained results may open a way for designing new cytidine based drugs or more potent CDA inhibitors.
authors.affiliation: School of Veterinary Medical Sciences, University of Camerino, Via Circonvallazione 93/95, 62024 Matelica (MC), Italy. silvia.vincenzetti@unicam.it
authors.forename: Silvia
authors.initials: S
authors.lastname: Vincenzetti
authors.forename: Stefania
authors.initials: S
authors.lastname: Pucciarelli
authors.forename: Francesco M
authors.initials: FM
authors.lastname: Carpi
authors.forename: Daniela
authors.initials: D
authors.lastname: Micozzi
authors.forename: Valeria
authors.initials: V
authors.lastname: Polzonetti
authors.forename: Paolo
authors.initials: P
authors.lastname: Natalini
authors.forename: Ivano
authors.initials: I
authors.lastname: Santarelli
authors.forename: Paolo
authors.initials: P
authors.lastname: Polidori
authors.forename: Alberto
authors.initials: A
authors.lastname: Vita
mesh_terms: D000595:Amino Acid Sequence; D020134:Catalytic Domain; D003564:Cytidine Deaminase / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D021122:Protein Subunits; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D016415:Sequence Alignment
chemical_list: D021122:Protein Subunits; D011994:Recombinant Proteins; D003564:Cytidine Deaminase