title: Double-strand break of giant DNA: protection by glucosyl-hesperidin as evidenced through direct observation on individual DNA molecules.
abstract: We have performed a real-time observation of photo-induced breakage on individual long DNA molecules stained by a cyanine dye, YOYO, under the intense illumination (lambda=450-490 nm) in solution. It was shown that the double-strand breakage is accelerated by Fenton's reagent (Fe2+/H2O2). In addition, it was found that the breakage reaction is protected in the presence of a water-soluble flavonoid, glucosyl-hesperidin. To interpret the kinetic process of the double-strand breakage reaction, a two-step mechanism is proposed: under light illumination on giant DNA molecules, single-strand breaks are generated to induce nicks in a stochastic manner, and then reactive oxygen attacks these nicks causing the double-strand break.
authors.affiliation: Department of Food and Nutrition, Nagoya Bunri College, Nagoya 451-0077, Japan. yuko@chem.scphys.kyoto-u.ac.jp
authors.forename: Yuko
authors.initials: Y
authors.lastname: Yoshikawa
authors.forename: Mari
authors.initials: M
authors.lastname: Suzuki
authors.forename: Norihiro
authors.initials: N
authors.lastname: Yamada
authors.forename: Kenichi
authors.initials: K
authors.lastname: Yoshikawa
mesh_terms: D017122:Bacteriophage T4 / Q000235:genetics; D001583:Benzoxazoles / Q000737:chemistry; D004249:DNA Damage; D004279:DNA, Viral / Q000737:chemistry* / Q000187:drug effects* / Q000528:radiation effects / Q000648:ultrastructure; D006031:Glycosylation; D006569:Hesperidin / Q000031:analogs & derivatives / Q000494:pharmacology*; D006861:Hydrogen Peroxide / Q000494:pharmacology; D007501:Iron / Q000494:pharmacology; D007700:Kinetics; D008856:Microscopy, Fluorescence; D009690:Nucleic Acid Conformation; D010777:Photochemistry; D011806:Quinolinium Compounds / Q000737:chemistry; D011837:Radiation-Protective Agents / Q000494:pharmacology
chemical_list: D001583:Benzoxazoles; D004279:DNA, Viral; C045076:Fenton's reagent; D011806:Quinolinium Compounds; D011837:Radiation-Protective Agents; C075296:1,1'-((4,4,7,7-tetramethyl)-4,7-diazaundecamethylene)bis-4-(3-methyl-2,3-dihydro(benzo-1,3-oxazole)-2-methylidene)quinolinium; D006861:Hydrogen Peroxide; D007501:Iron; D006569:Hesperidin