Ultrafast transient-absorption and steady-state fluorescence measurements on 2-aminopurine substituted dinucleotides and 2-aminopurine substituted DNA duplexes

Olaf F.A. Larsen, Ivo H.M. Van Stokkum, Frank L. De Weerd, Mikas Vengris, Charuvila T. Aravindakumar, Rienk Van Grondelle, Nicholas E. Geacintov, Herbert Van Amerongen

Research output: Contribution to journalArticle

Abstract

Ultrafast transient-absorption and steady-state fluorescence measurements have been performed on dinucleotides comprising the fluorescent adenine analogue 2-aminopurine and guanine, adenine, cytosine, thymine or hypoxanthine, respectively. Two oligodeoxyribonucleotide duplexes that were site-selectively substituted with a single 2-aminopurine moiety were also studied. A strong quenching of the steady-state fluorescence was observed in all samples. The transient-absorption spectra were remarkably similar to those of the isolated 2-aminopurine (Larsen et al.; O. F. A. Larsen, I. H. M. van Stokkum, M.-L. Groot, J. T. M. Kennis, R. van Grondelle and H. van Amerongen, Chem. Phys. Lett., 2003, 371, 157-163), exhibiting both a fluorescent and a non-fluorescent excited state. There was no evidence for significant amounts of charge-separated states in the transient-absorption spectra. The probability that an excitation of 2AP leads to stable charge transfer products was estimated to be very low (∼0.1%). In the systems we studied, the observed fluorescence quenching can largely be explained by a shift of the equilibrium between the two excited states in 2AP, in which the non-fluorescent state is favored.

Original languageEnglish (US)
Pages (from-to)154-160
Number of pages7
JournalPhysical Chemistry Chemical Physics
Volume6
Issue number1
DOIs
StatePublished - Jan 7 2004

ASJC Scopus subject areas

  • Physics and Astronomy(all)
  • Physical and Theoretical Chemistry

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