Competition between stacked and hydrogen bonded structures of cytosine aggregates

  1. González, J. 2
  2. Usabiaga, I. 2
  3. Arnaiz, P.F. 2
  4. León, I. 23
  5. Martínez, R. 1
  6. Millán, J. 1
  7. Fernández, J.A. 2
  1. 1 Universidad de La Rioja

    Universidad de La Rioja

    Logroño, España


  2. 2 Universidad del País Vasco/Euskal Herriko Unibertsitatea

    Universidad del País Vasco/Euskal Herriko Unibertsitatea

    Lejona, España


  3. 3 Universidad de Valladolid

    Universidad de Valladolid

    Valladolid, España


Physical Chemistry Chemical Physics

ISSN: 1463-9076

Year of publication: 2017

Volume: 19

Issue: 13

Pages: 8826-8834

Type: Article

DOI: 10.1039/C6CP08476A SCOPUS: 2-s2.0-85019382944 WoS: WOS:000399004700020 GOOGLE SCHOLAR

More publications in: Physical Chemistry Chemical Physics

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The four bases of DNA constitute what is known as the "alphabet of life". Their combination of proton-donor and acceptor groups and aromatic rings allows them to form stacking structures and at the same time establish hydrogen bonds with their counterparts, resulting in the formation of the well-known double-helix structure of DNA. Here we explore the aggregation preferences of cytosine in supersonic expansions, using a combination of laser spectroscopic techniques and computations. The data obtained from the experiments carried out in the cold and isolated environment of the expansion allowed us to establish which are the leading interactions behind aggregation of cytosine molecules. The results obtained demonstrated that ribbon-like structures held together by hydrogen bonds are the preferred conformations in the small clusters, but once the tetramer was reached, the stacking structures became enthalpically more stable. Stacking is further favoured when cytosine is replaced by its 1′-methylated version, as demonstrated by quantum-mechanical calculations performed using the same level that reproduced the experimental results obtained for cytosine aggregates. A discussion on the biological implications that such observations may have is also offered. © the Owner Societies.