Linked Life Data

18225886

Source:http://linkedlifedata.com/resource/pubmed/id/18225886

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
7
pubmed:dateCreated
2008-2-14
pubmed:abstractText
In previous work, we have shown that photoexcitation of guanine cation radical (G*+) in frozen aqueous solutions of DNA and its model compounds at 143 K results in the formation of neutral sugar radicals with substantial yield. In this report, we present electron spin resonance (ESR) and theoretical (DFT) evidence regarding the formation of sugar radicals after photoexcitation of guanine cation radical (G*+) in frozen aqueous solutions of one-electron-oxidized RNA model compounds (nucleosides, nucleotides and oligomers) at 143 K. Specific sugar radicals C5'*, C3'* and C1'* were identified employing derivatives of Guo deuterated at specific sites in the sugar moiety, namely, C1'-, C2'-, C3'- and C5'-. These results suggest C2'* is not formed upon photoexcitation of G*+ in one-electron-oxidized Guo and deuterated Guo derivatives. Phosphate substitution at C5'- (i.e., in 5-GMP) hinders formation of C5'* via photoexcitation at 143 K but not at 77 K. For the RNA-oligomers studied, we observe on photoexcitation of oligomer-G*+ the formation of mainly C1'* and an unidentified radical with a ca. 28 G doublet. The hyperfine coupling constants of each of the possible sugar radicals were calculated employing the DFT B3LYP/6-31G* approach for comparison to experiment. This work shows that formation of specific neutral sugar radicals occurs via photoexcitation of guanine cation radical (G*+) in RNA systems but not by photoexcitation of its N1 deprotonated species (G(-H)*). Thus, our mechanism regarding neutral sugar formation via photoexcitation of base cation radicals in DNA appears to be valid for RNA systems as well.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Feb
pubmed:issn
1520-6106
pubmed:author
pubmed:issnType
Print
pubmed:day
21
pubmed:volume
112
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
2168-78
pubmed:meshHeading
pubmed:year
2008
pubmed:articleTitle
Formation of sugar radicals in RNA model systems and oligomers via excitation of guanine cation radical.
pubmed:affiliation
Department of Chemistry, Oakland University, Rochester, Michigan 48309, USA.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't, Research Support, N.I.H., Extramural