title: DNA oxidation, strand-breaks and etheno-adducts formation promoted by Cu, Zn-superoxide dismutase-H2O2 in the presence and absence of bicarbonate.
abstract: Biomolecule oxidation promoted by Cu, Zn-superoxide dismutase (SOD1) has been studied because of its potential role in neurodegenerative diseases. We studied the mechanism of DNA damage promoted by the SOD1-H2O2 system. The system promoted the formation of strand breaks in plasmid DNA and the formation of 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodGuo) in calf thymus DNA. We were also able to detect, for the first time, 1,N2-etheno-2'-deoxyguanosine (1,N'-epsilondGuo) in calf thymus DNA exposed to SOD1-H2O2. The addition of a copper chelator caused a decrease in the frequency of 8-oxodGuo and 1,N2-epsilondGuo, indicating the participation of copper ions lost from SOD1 active sites. The addition of bicarbonate increased the levels of both DNA lesions. We conclude that copper liberated from SODI active sites has a central role in the mechanism of DNA damage promoted by SOD1 in the presence of H2O2, and that bicarbonate can modulate the reactivity of released copper.
authors.affiliation: Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, Av. Prof. Lineu Prestes 748, CEP 05508-900, São Paulo, SP, Brazil.
authors.forename: Lívea Fujita
authors.initials: LF
authors.lastname: Barbosa
authors.forename: Camila Carrião Machado
authors.initials: CC
authors.lastname: Garcia
authors.forename: Paolo
authors.initials: P
authors.lastname: Di Mascio
authors.forename: Marisa Helena Gennari
authors.initials: MH
authors.lastname: de Medeiros
mesh_terms: D001639:Bicarbonates / Q000737:chemistry*; D002851:Chromatography, High Pressure Liquid; D004247:DNA / Q000737:chemistry*; D004249:DNA Damage; D004563:Electrochemistry; D006861:Hydrogen Peroxide / Q000737:chemistry*; D010084:Oxidation-Reduction; D010957:Plasmids; D021241:Spectrometry, Mass, Electrospray Ionization; D013054:Spectrophotometry, Atomic; D013482:Superoxide Dismutase / Q000737:chemistry*; D053719:Tandem Mass Spectrometry
chemical_list: D001639:Bicarbonates; D004247:DNA; D006861:Hydrogen Peroxide; D013482:Superoxide Dismutase