Watson-crick base pairs with thiocarbonyl groups: How sulfur changes the hydrogen bonds in DNA |
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Authors: | Célia Fonseca Guerra Evert Jan Baerends F Matthias Bickelhaupt |
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Institution: | (1) Theoretische Chemie, Scheikundig Laboratorium der Vrije Universiteit, De Boelelaan 1083, NL-1081 HV Amsterdam, The Netherlands |
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Abstract: | We have theoretically analyzed mimics of Watson-Crick AT and GC base pairs in which N-H···O hydrogen bonds are replaced by
N-H···S, using the generalized gradient approximation (GGA) of density functional theory at BP86/TZ2P level. The general effect
of the above substitutions is an elongation and a slight weakening of the hydrogen bonds that hold together the base pairs.
However, the precise effects depend on how many, and in particular, on which hydrogen bonds AT and GC are substituted.. Another
purpose of this work is to clarify the relative importance of electrostatic attraction versus orbital interaction in the hydrogen bonds involved in the mimics, using a quantitative bond energy decomposition scheme.
At variance with widespread believe, the orbital interaction component in these hydrogen bonds is found to contribute more
than 40% of the attractive interactions and is thus of the same order of magnitude as the electrostatic component, which provides
the remaining attraction.
![MediaObjects/11532_2006_Article_68_Fig1_HTML.jpg](/content/v0k821366v603w22/MediaObjects/11532_2006_Article_68_Fig1_HTML.jpg) |
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Keywords: | Chitosan Density functional calculations DNA structures Sulfur Hydrogen bonds Watson-Crick pair mimics |
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