UVA-visible photo-excitation of guanine radical cations produces sugar radicals in DNA and model structures

This work presents evidence that photo-excitation of guanine radical cations results in high yields of deoxyribose sugar radicals in DNA, guanine deoxyribonucleosides and deoxyribonucleotides. In dsDNA at low temperatures, formation of C1′• is observed from photo-excitation of G•+ in the 310–480 nm...

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Main Authors:	Adhikary, Amitava, Malkhasian, Aramice Y. S., Collins, Sean, Koppen, Jessica, Becker, David, Sevilla, Michael D.
Format:	Online
Language:	English
Published:	Oxford University Press 2005
Online Access:	https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1243799/

id	pubmed-1243799
recordtype	oai_dc
spelling	pubmed-12437992005-10-12 UVA-visible photo-excitation of guanine radical cations produces sugar radicals in DNA and model structures Adhikary, Amitava Malkhasian, Aramice Y. S. Collins, Sean Koppen, Jessica Becker, David Sevilla, Michael D. Article This work presents evidence that photo-excitation of guanine radical cations results in high yields of deoxyribose sugar radicals in DNA, guanine deoxyribonucleosides and deoxyribonucleotides. In dsDNA at low temperatures, formation of C1′• is observed from photo-excitation of G•+ in the 310–480 nm range with no C1′• formation observed ≥520 nm. Illumination of guanine radical cations in 2′dG, 3′-dGMP and 5′-dGMP in aqueous LiCl glasses at 143 K is found to result in remarkably high yields (∼85–95%) of sugar radicals, namely C1′•, C3′• and C5′•. The amount of each of the sugar radicals formed varies dramatically with compound structure and temperature of illumination. Radical assignments were confirmed using selective deuteration at C5′ or C3′ in 2′-dG and at C8 in all the guanine nucleosides/tides. Studies of the effect of temperature, pH, and wavelength of excitation provide important information about the mechanism of formation of these sugar radicals. Time-dependent density functional theory calculations verify that specific excited states in G•+ show considerable hole delocalization into the sugar structure, in accord with our proposed mechanism of action, namely deprotonation from the sugar moiety of the excited molecular radical cation. Oxford University Press 2005 2005-10-04 /pmc/articles/PMC1243799/ /pubmed/16204456 http://dx.doi.org/10.1093/nar/gki857 Text en © The Author 2005. Published by Oxford University Press. All rights reserved
repository_type	Open Access Journal
institution_category	Foreign Institution
institution	US National Center for Biotechnology Information
building	NCBI PubMed
collection	Online Access
language	English
format	Online
author	Adhikary, Amitava Malkhasian, Aramice Y. S. Collins, Sean Koppen, Jessica Becker, David Sevilla, Michael D.
spellingShingle	Adhikary, Amitava Malkhasian, Aramice Y. S. Collins, Sean Koppen, Jessica Becker, David Sevilla, Michael D. UVA-visible photo-excitation of guanine radical cations produces sugar radicals in DNA and model structures
author_facet	Adhikary, Amitava Malkhasian, Aramice Y. S. Collins, Sean Koppen, Jessica Becker, David Sevilla, Michael D.
author_sort	Adhikary, Amitava
title	UVA-visible photo-excitation of guanine radical cations produces sugar radicals in DNA and model structures
title_short	UVA-visible photo-excitation of guanine radical cations produces sugar radicals in DNA and model structures
title_full	UVA-visible photo-excitation of guanine radical cations produces sugar radicals in DNA and model structures
title_fullStr	UVA-visible photo-excitation of guanine radical cations produces sugar radicals in DNA and model structures
title_full_unstemmed	UVA-visible photo-excitation of guanine radical cations produces sugar radicals in DNA and model structures
title_sort	uva-visible photo-excitation of guanine radical cations produces sugar radicals in dna and model structures
description	This work presents evidence that photo-excitation of guanine radical cations results in high yields of deoxyribose sugar radicals in DNA, guanine deoxyribonucleosides and deoxyribonucleotides. In dsDNA at low temperatures, formation of C1′• is observed from photo-excitation of G•+ in the 310–480 nm range with no C1′• formation observed ≥520 nm. Illumination of guanine radical cations in 2′dG, 3′-dGMP and 5′-dGMP in aqueous LiCl glasses at 143 K is found to result in remarkably high yields (∼85–95%) of sugar radicals, namely C1′•, C3′• and C5′•. The amount of each of the sugar radicals formed varies dramatically with compound structure and temperature of illumination. Radical assignments were confirmed using selective deuteration at C5′ or C3′ in 2′-dG and at C8 in all the guanine nucleosides/tides. Studies of the effect of temperature, pH, and wavelength of excitation provide important information about the mechanism of formation of these sugar radicals. Time-dependent density functional theory calculations verify that specific excited states in G•+ show considerable hole delocalization into the sugar structure, in accord with our proposed mechanism of action, namely deprotonation from the sugar moiety of the excited molecular radical cation.
publisher	Oxford University Press
publishDate	2005
url	https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1243799/
_version_	1611378247608565760

UVA-visible photo-excitation of guanine radical cations produces sugar radicals in DNA and model structures

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