Reaction mechanisms of riboflavin triplet state with nucleic acid bases.
ESR and laser flash photolysis studies have determined a reasonable order of reactivity of nucleotides with triplet riboflavin (3Rb*) for the first time. ESR detection of triplet state reactivity of Rb with nucleoside, polynucleotide and DNA has been obtained simultaneously. In addition, ESR spin elimination measurement of the reactivity of 3Rb* with nucleotides in good accord with laser flash photolysis determination of the corresponding rate constants offers a simple and reliable method to detect the reactivities of nucleic acids and its components with photoexcited flavins. Kinetic, ESR and thermodynamic studies have demonstrated that Rb should be a strong endogenous photosensitizer capable of oxidizing all nucleic acid bases, and preferentially two purine nucleotides with high rate constants.
Laboratory of Nuclear Analysis Technique and Laboratory of Radiation Chemistry, Shanghai Institute of Applied Physics, Chinese Academy of Sciences, P. O. Box: 800-204, Shanghai, 201800, China. linweizhen@sinap.ac.cn
Weizhen
W
Lin
Changyuan
C
Lu
Fuqiang
F
Du
Zhiyong
Z
Shao
Zhenhui
Z
Han
Tiecheng
T
Tu
Side
S
Yao
Nianyun
N
Lin
D003497:Cyclic N-Oxides / Q000737:chemistry; D004247:DNA / Q000737:chemistry*; D004578:Electron Spin Resonance Spectroscopy; D008027:Light; D010084:Oxidation-Reduction; D010782:Photolysis; D017319:Photosensitizing Agents / Q000737:chemistry*; D011684:Purine Nucleosides / Q000737:chemistry*; D012256:Riboflavin / Q000737:chemistry*; D013113:Spin Labels
D003497:Cyclic N-Oxides; D017319:Photosensitizing Agents; D011684:Purine Nucleosides; D013113:Spin Labels; D004247:DNA; D012256:Riboflavin; C003959:TEMPO