QUINONE SENSITIZED ELECTRON TRANSFER PHOTOOXIDATION OF NUCLEIC ACIDS: CHEMISTRY OF THYMINE AND THYMIDINE RADICAL CATIONS IN AQUEOUS SOLUTION*

Download
  1. Get@NRC: QUINONE SENSITIZED ELECTRON TRANSFER PHOTOOXIDATION OF NUCLEIC ACIDS: CHEMISTRY OF THYMINE AND THYMIDINE RADICAL CATIONS IN AQUEOUS SOLUTION* (Opens in a new window)
DOIResolve DOI: http://doi.org/10.1111/j.1751-1097.1990.tb04189.x
AuthorSearch for: ; Search for: ; Search for:
TypeArticle
Journal titlePhotochemistry and Photobiology
Volume52
Issue2
Pages333343; # of pages: 11
AbstractThe 2-methyl-l,4-naphthoquinone (MQ) sensitized photooxidation of nucleic acid derivatives has been studied by laser flash photolysis and steady state methods. Thymine and thymidine, as well as other DNA model compounds, quench triplet MQ by electron transfer to give MQ radical anions and pyrimidine or purine radical cations. Although the pyrimidine radical cations cannot be directly observed by flash photolysis, the addition of N,N,N',N'-tetramethyl-l,4-phenylenediamine (TMPD) results in the formation of the TMPD radical cation via scavenging of the pyrimidine radical cation. The photooxidation products for thymine and thymidine are shown to result from subsequent chemical reactions of the radical cations in oxygenated aqueous solution. The quantum yield for substrate loss at limiting substrate concentrations is 0.38 for thymine and 0.66 for thymidine. The chemistry of the radical cations involves hydration by water leading to C(6)-OH adduct radicals of the pyrimidine and deprotonation from the N(l) position in thymine and the C(5) methyl group for thymidine. Superoxide ions produced via quenching of the quinone radical anion with oxygen appear to be involved in the formation of thymine and thymidine hydroperoxides and in the reaction with N(l)-thyminyl radicals to regenerate thymine. The effects of pH were examined in the range pH 520138 in both the presence and absence of superoxide dismutase. Initial C(6)-OH thymine adducts are suggested to dehydrate to give N(l)-thyminyl radicals.
Publication date
AffiliationNational Research Council Canada; NRC Steacie Institute for Molecular Sciences
Peer reviewedNo
NPARC number12338944
Export citationExport as RIS
Report a correctionReport a correction
Record identifierbfdf6519-6751-4413-9cb1-81e545fb03fb
Record created2009-09-11
Record modified2016-05-09
Bookmark and share
  • Share this page with Facebook (Opens in a new window)
  • Share this page with Twitter (Opens in a new window)
  • Share this page with Google+ (Opens in a new window)
  • Share this page with Delicious (Opens in a new window)