http://www.cnr.it/ontology/cnr/individuo/prodotto/ID300990

Efficient UV-induced charge separation and recombination in an 8-oxoguanine-containing dinucleotide (Articolo in rivista)

Type

Label

Efficient UV-induced charge separation and recombination in an 8-oxoguanine-containing dinucleotide (Articolo in rivista) (literal)

Anno

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Alternative label

Zhang, Yuyuan; Dood, Jordan; Beckstead, Ashley A.; Li, Xi-Bo; Nguyen, Khiem V.; Burrows, Cynthia J.; Improta, Roberto; Kohler, Bern (2014)
Efficient UV-induced charge separation and recombination in an 8-oxoguanine-containing dinucleotide
in Proceedings of the National Academy of Sciences of the United States of America
(literal)

Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#autori

Zhang, Yuyuan; Dood, Jordan; Beckstead, Ashley A.; Li, Xi-Bo; Nguyen, Khiem V.; Burrows, Cynthia J.; Improta, Roberto; Kohler, Bern (literal)

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Note

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Montana State University; University of Utah; Consiglio Nazionale delle Ricerche (CNR) (literal)

Titolo

Efficient UV-induced charge separation and recombination in an 8-oxoguanine-containing dinucleotide (literal)

Abstract

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. (literal)

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