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Cited by 411

The DOI matches its Crossref record; 56 of the 56 references it cites were found in a registry or an index.

DNA Excited-State Dynamics: Ultrafast Internal Conversion and Vibrational Cooling in a Series of Nucleosides

Pecourt, Jean-Marc L., Peon, Jorge, Kohler, Bern·2001·Journal of the American Chemical Society
DOI 10.1021/ja0161453
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Abstract

To better understand DNA photodamage, several nucleosides were studied by femtosecond transient absorption spectroscopy. A 263-nm, 150-fs ultraviolet pump pulse excited each nucleoside in aqueous solution, and the subsequent dynamics were followed by transient absorption of a femtosecond continuum pulse at wavelengths between 270 and 700 nm. A transient absorption band with maximum amplitude near 600 nm was detected in protonated guanosine at pH 2. This band decayed in 191 +/- 4 ps in excellent agreement with the known fluorescence lifetime, indicating that it arises from absorption by the lowest excited singlet state. Excited state absorption for guanosine and the other nucleosides at pH 7 was observed in the same spectral region, but decayed on a subpicosecond time scale by internal conversion to the electronic ground state. The cross section for excited state absorption is very weak for all nucleosides studied, making some amount of two-photon ionization of the solvent unavoidable. The excited state lifetimes of Ado, Guo, Cyd, and Thd were determined to be 290, 460, 720, and 540 fs, respectively (uncertainties are +/-40 fs). The decay times are shorter for the purines than for the pyrimidine bases, consistent with their lower propensity for photochemical damage. Following internal conversion, vibrationally highly excited ground state molecules were detected in experiments on Ado and Cyd by hot ground state absorption at ultraviolet wavelengths. The decays are assigned to intermolecular vibrational energy transfer to the solvent. The longest time constant observed for Ado is approximately 2 ps, and we propose that solute-solvent H-bonds are responsible for this fast rate of vibrational cooling. The results show for the first time that excited singlet state dynamics of the DNA bases can be directly studied at room temperature. Like sunscreens that function by light absorption, the bases rapidly convert dangerous electronic energy into heat, and this property is likely to have played a critical role in life's early evolution on earth.

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Metadata

Authors
Pecourt, J.-M. L., Peon, J., & Kohler, B.
Venue
Journal of the American Chemical Society
Publisher
American Chemical Society (ACS)
Published
2001-10-01
Volume
123
Issue
42
Pages
10370-10378
ISSN
  • 0002-7863 (ISSN-L)
  • 1520-5126
DOI
10.1021/ja0161453
OpenAlex
W2020678264
Cited by
411
References
56
FWCI
11.18
Type
journal article
Language
en
Open access
closed

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