title: Complexes of DNA bases and Watson-Crick base pairs with small neutral gold clusters.
abstract: The nature of the DNA-gold interaction determines and differentiates the affinity of the nucleobases (adenine, thymine, guanine, and cytosine) to gold. Our preliminary computational study [Kryachko, E. S.; Remacle, F. Nano Lett. 2005, 5, 735] demonstrates that two major bonding factors govern this interaction: the anchoring, either of the Au-N or Au-O type, and the nonconventional N-H...Au hydrogen bonding. In this paper, we offer insight into the nature of nucleobase-gold interactions and provide a detailed characterization of their different facets, i.e., geometrical, energetic, and spectroscopic aspects; the gold cluster size and gold coordination effects; proton affinity; and deprotonation energy. We then investigate how the Watson-Crick DNA pairing patterns are modulated by the nucleobase-gold interaction. We do so in terms of the proton affinities and deprotonation energies of those proton acceptors and proton donors which are involved in the interbase hydrogen bondings. A variety of properties of the most stable Watson-Crick [A x T]-Au3 and [G x C]-Au3 hybridized complexes are described and compared with the isolated Watson-Crick A x T and G x C ones. It is shown that enlarging the gold cluster size to Au6 results in a rather short gold-gold bond in the Watson-Crick interbase region of the [G x C]-Au6 complex that bridges the G x C pair and thus leads to a significant strengthening of G x C pairing.
authors.affiliation: Department of Chemistry, Bat. B6c, University of Liège, B-4000 Liège, Belgium. eugene.kryachko@ulg.ac.be
authors.forename: E S
authors.initials: ES
authors.lastname: Kryachko
authors.forename: F
authors.initials: F
authors.lastname: Remacle
mesh_terms: D020029:Base Pairing; D004247:DNA / Q000737:chemistry*; D006046:Gold / Q000737:chemistry*; D006860:Hydrogen Bonding; D008956:Models, Chemical; D011687:Purines / Q000737:chemistry*; D011743:Pyrimidines / Q000737:chemistry*
chemical_list: D011687:Purines; D011743:Pyrimidines; D006046:Gold; D004247:DNA