Electron donor-acceptor interactions with flanking purines influence the efficiency of thymine photodimerization

Zhengzheng Pan, Mahesh Hariharan, Joshua D. Arkin, Almaz S. Jalilov, Martin McCullagh, George C. Schatz, Frederick D. Lewis

Research output: Contribution to journalArticlepeer-review

41 Citations (Scopus)


Quantum yields for thymine photodimerization (φTT) have been determined for a series of short DNA single-strand and base-paired hairpin structures possessing a single thymine-thymine step with flanking purines. Values of φTT are strongly dependent upon the oxidation potential of the flanking purine, decreasing in the order: inosine > adenine > guanine > deazaguanine. The dependence of φTT on the ionization potential of the flanking purine is more pronounced when the purine of lower oxidation potential is located at the 5′- versus 3′-position in either a single strand or a hairpin. Molecular dynamics simulations for hairpin structures indicate that the TT step is π-stacked with both the 5′ and 3′ purine, but that there is little π-stacking with either purine in single-strand structures. The observation of moderately intense long-wavelength UV absorption features for hairpins having 5′-Z or G flanking purines suggests that excitation of ground state donor-acceptor complexes may account for more extensive quenching of dimerization by 5′- versus 3′-purines. The "purine effect" on φTT is attributed to a combination of ground state conformation, ground state electron donor-acceptor interactions, and excited state exciplex formation.

Original languageEnglish
Pages (from-to)20793-20798
Number of pages6
JournalJournal of the American Chemical Society
Issue number51
Publication statusPublished - Dec 28 2011

ASJC Scopus subject areas

  • Catalysis
  • Chemistry(all)
  • Biochemistry
  • Colloid and Surface Chemistry

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