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Complexes of DNA Bases and Watson−Crick Base Pairs with Small Neutral Gold Clusters

2005; American Chemical Society; Volume: 109; Issue: 48 Linguagem: Inglês

10.1021/jp054708h

1520-6106

Eugene S. Kryachko, F. Remacle,

Advanced biosensing and bioanalysis techniques

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·T]−Au3 and [G·C]−Au3 hybridized complexes are described and compared with the isolated Watson−Crick A·T and G·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·C]−Au6 complex that bridges the G·C pair and thus leads to a significant strengthening of G·C pairing.