title: The pH-dependent role of superoxide in riboflavin-catalyzed photooxidation of 8-oxo-7,8-dihydroguanosine.
abstract: [reaction: see text]. The riboflavin-catalyzed photooxidation of 2',3',5'-tri-O-acetyl-8-oxo-7,8-dihydroguanosine generates a radical intermediate that is competitively trapped by H(2)O, O2(-)(*), or O(2). The products of H(2)O trapping have been previously described as the spiroiminodihydantoin (pH >or= 7) and iminoallantoin/guanidinohydantoin (pH < 7) nucleosides. Trapping by O2(-)(*) leads to the oxaluric acid (pH <or= 7) and imidazolone (pH >or= 8.6) pathways (R' ', R' ' = H or 2,3,5-tri-O-Ac-ribofuranosyl). The pH-dependent role of superoxide was probed using Mn-SOD and compared to guanosine and 8-methoxyguanosine photooxidation.
authors.affiliation: Department of Chemistry, University of Utah, 315 South 1400 East, Salt Lake City, Utah 84112-0850, USA.
authors.forename: W
authors.initials: W
authors.lastname: Luo
authors.forename: J G
authors.initials: JG
authors.lastname: Muller
authors.forename: C J
authors.initials: CJ
authors.lastname: Burrows
mesh_terms: D002384:Catalysis; D006151:Guanosine / Q000031:analogs & derivatives* / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D007093:Imidazoles / Q000737:chemistry; D010072:Oxamic Acid / Q000031:analogs & derivatives* / Q000737:chemistry; D010084:Oxidation-Reduction; D010777:Photochemistry; D012256:Riboflavin / Q000737:chemistry*; D013481:Superoxides / Q000737:chemistry*
chemical_list: D007093:Imidazoles; C117197:imidazolone; D013481:Superoxides; D006151:Guanosine; C046215:8-hydroxyguanosine; C008727:oxaluric acid; C046214:8-methoxyguanosine; D010072:Oxamic Acid; D012256:Riboflavin