Efficient UV-induced charge separation and recombination in an 8-oxoguanine-containing dinucleotide(560 views) Zhang Y, Dood J, Beckstead AA, Li X-B, Nguyen KV, Burrows CJ, Improta R, Kohler B
P Natl Acad Sci Usa (ISSN: 0027-8424, 1091-6490, 0027-8424print), 2014 Sep 12; 111(32): 11612-11617.
Keywords: Base Pairing, Biogenesis, Electron Transport Radiation Effects, Guanine Analogs, Derivatives Chemistry, Kinetics, Models, Chemical, Oligonucleotides Chemistry Radiation Effects, Photochemical Processes, Quantum Theory, Spectrophotometry, Atomic, Spectroscopy, Fourier Transform Infrared, Thermodynamics, Ultraviolet Rays, Dna Charge Transfer States, Dna Photophysics, Ab Initio Calculations, Photoreactivation, Time-Resolved Vibrational Spectroscopy, 8 Hydroxyguanine, Deoxyadenosine, Dinucleotide, Absorption, Absorption Spectroscopy, Aqueous Solution, Article, Density Functional Theory, Excitation, Infrared Spectroscopy, Priority Journal, Quantum Mechanics, Quantum Yield, Time Resolved Infrared Spectroscopy, Ultraviolet Radiation,
Affiliations: *** IBB - CNR ***
Department of Chemistry and Biochemistry, Montana State University, Bozeman, MT 59717
and kohler@chemistry.montana.edu burrows@chem.utah.edu robimp@unina.it.
Consiglio Nazionale delle Ricerche, Istituto di Biostrutture e Bioimmagini, 80136 Naples, Italy kohler@chemistry.montana.edu burrows@chem.utah.edu robimp@unina.it.
References: Not available.
Efficient UV-induced charge separation and recombination in an 8-oxoguanine-containing dinucleotide
During the early evolution of life, 8-oxo-7,8-dihydro-2'-deoxyguanosine (O) may have functioned as a proto-flavin capable of repairing cyclobutane pyrimidine dimers in DNA or RNA by photoinduced electron transfer using longer wavelength UVB radiation. To investigate the ability of O to act as an excited-state electron donor, a dinucleotide mimic of the FADH(2) cofactor containing O at the 5'-end and 2'-deoxyadenosine at the 3'-end was studied by femto-second transient absorption spectroscopy in aqueous solution. Following excitation with a UV pulse, a broadband mid-IR pulse probed vibrational modes of ground-state and electronically excited molecules in the double-bond stretching region. Global analysis of time- and frequency-resolved transient absorption data coupled with ab initio quantum mechanical calculations reveal vibrational marker bands of nucleobase radical ions formed by electron transfer from O to 2'-deoxyadenosine. The quantum yield of charge separation is 0.4 at 265 nm, but decreases to 0.1 at 295 nm. Charge recombination occurs in 60 ps before the O radical cation can lose a deuteron to water. Kinetic and thermodynamic considerations strongly suggest that all nucleobases can undergo ultrafast charge separation when p-stacked in DNA or RNA. Interbase charge transfer is proposed to be a major decay pathway for UV excited states of nucleic acids of great importance for photostability as well as photoredox activity.
Efficient UV-induced charge separation and recombination in an 8-oxoguanine-containing dinucleotide
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Efficient UV-induced charge separation and recombination in an 8-oxoguanine-containing dinucleotide