Theoretical model of the aqua-copper [Cu(H2O)5]+cation interactions with guanine |
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Authors: | Jaroslav V Burda Manoj K Shukla Jerzy Leszczynski |
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Institution: | (1) Department of Chemical Physics and Optics, Faculty of Mathematics and Physics, Charles University, Ke Karlovu 3, 121 16 Prague 2, Czech Republic;(2) Computational Center for Molecular Structure and Interactions, Department of Chemistry, Jackson State University, 1325 J. R. Lynch Street, Jackson, MS 39217-0510, USA |
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Abstract: | Pentaaqua complexes of Cu(I) with guanine were optimized at the DFT B3PW91/6-31G(d) level. For the most stable structures, vibration frequencies and NBO charges were computed followed by energy analyses. The order of individual conformers was very sensitive to the method and basis sets used for the calculation. Several conformers are practically degenerated in energy. The inclusion of an entropy term changes the order of the conformers stability. Water molecules associated at the N9 position of guanine are favored by the inclusion of the entropy correction. Bonding energies of Cu–O(aqua) interactions were estimated to be about 60 kcal mol–1 and for Cu–N7 bonding in the range of 75–83 kcal mol–1. The broad range in Cu–N interaction energies demonstrates the role of induction effects caused by water molecules associated at the various sites of guanine. The charge distribution of the guanine molecule is changed remarkably by the coordination of a Cu(I) cation, which can also change the base-pairing pattern of the guanine. |
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Keywords: | DFT calculations Copper complexes DNA base Metal hydration |
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