AVS 51st International Symposium
    Surface Science Monday Sessions
       Session SS2-MoA

Paper SS2-MoA9
Resonance-Assisted Hydrogen Bonds Stabilize Guanine Quartet Networks on Solid Surfaces

Monday, November 15, 2004, 4:40 pm, Room 210C

Session: Assembled Monolayers
Presenter: R. Otero, University of Aarhus, Denmark
Authors: R. Otero, University of Aarhus, Denmark
M. Schöck, University of Aarhus, Denmark
L.M. Molina, University of Aarhus, Denmark
E. Laegsgaard, University of Aarhus, Denmark
I. Stensgaard, University of Aarhus, Denmark
B. Hammer, University of Aarhus, Denmark
F. Besenbacher, University of Aarhus, Denmark
Correspondent: Click to Email
Hydrogen bonding between DNA bases is one of the main interactions that control the conformation and hence the biochemical function of nucleic acid molecules@footnote 1,2@. Apart from the Watson-Crick model for base pairing@footnote 1@, DNA bases can form other hydrogen-bonded complexes that lead to different DNA structures, like G-quadruplexes@footnote 3@ or i-motifs@footnote 4@. In spite of the increasing evidence for the existence and in vivo function of these DNA structures@footnote 5@, a convincing biophysical model for their stability is still missing. By combining high-resolution, variable-temperature Scanning Tunneling Microscopy (STM) and state-of-the-art Density Functional Theory (DFT), here we show that the DNA base guanine (G) deposited under ultra-clean conditions onto a suitably inert substrate such as Au(111) self-assembles into a hydrogen-bonded network of G-quartets, whose structure corresponds perfectly with the quartet structure of telomeric DNA@footnote 3@ determined by X-ray crystallography. The strong preference of G molecules to form quartets can be explained by a cooperative effect that strengthens the hydrogen bonds within the G-quartet network over the hydrogen bonds in isolated dimers. This result underlines the necessity of going beyond the picture of isolated hydrogen bonds in order to properly describe the interactions between biomolecules. @FootnoteText@ @footnote 1@ Watson, J. D. & Crick, F. H. C. A structure for deoxyribose nucleic acid. Nature 171, 737-738 (1953).@footnote 2@ Sinden, R. R. DNA Structure and Function (Academic Press, San Diego, 1994).@footnote 3@ Sundquist, W. I. & Klug, A. Telomeric DNA dimerizes by formation of guanine tetrads between hairpin loops. Nature 342, 825-829 (1989).@footnote 4@ Gehring, K., Leroy, J.-L. & Guéron, M. A tetrameric DNA structure with protonated cytosine-cytosine base pairs. Nature 363, 561-565 (1993).@footnote 5@ Kipling, D. The telomere (Oxford University Press, Oxford, 2002).