Photochemical selectivity in guanine-cytosine base-pair structures

Ali Abo-Riziq, Louis Grace, Eyal Nir, Martin Kabelac, Pavel Hobza, Mattanjah S. De Vries

Research output: Contribution to journalArticlepeer-review

231 Scopus citations


Prebiotic chemistry presumably took place before formation of an oxygen-rich atmosphere and thus under conditions of intense short wavelength UV irradiation. Therefore, the UV photochemical stability of the molecular building blocks of life may have been an important selective factor in determining the eventual chemical makeup of critical biomolecules. To investigate the role of UV irradiation in base-pairing we have studied guanine (G) and cytosine (C) base pairs in the absence of the RNA backbone. We distinguished base-pair structures by IR-UV hole-burning spectroscopy as well as by high-level correlated ab initio calculations. The Watson-Crick structure exhibits broad UV absorption, in stark contrast to other GC structures and other base-pair structures. This broad absorption may be explained by a rapid internal conversion that makes this specific base pair arrangement uniquely photochemically stable.

Original languageEnglish
Pages (from-to)20-23
Number of pages4
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number1
StatePublished - 4 Jan 2005
Externally publishedYes


  • DNA base pairs
  • IR-UV spectroscopy
  • Jet cooling
  • Photochemistry
  • ab initio computation

ASJC Scopus subject areas

  • General


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