Adenine-thymine interactions

Another pyrimidine base, uracil, is found in RNA instead of thymine. Base pairing between adenine and uracil involves two hydrogen bonds and resembles the adenine-thymine interaction. This type of base pairing is of importance in transcription, the synthesis of messenger RNA (see Section 14.2.5). 

Fig. 74 Selective binding and detachment of a PS-polymer via adenine/thymine interaction to/from a SAM surface. Reprinted with permission from [247]...

As found for other stacked base pairs, in the stacked thymine-thymine pair changes in the interaction energy upon rotation of one thymine unit are almost completely compensated for by solvation effects [99JPC(B)884]. The adenine-thymine (A-T) base pair, which possesses a significant degree of conformational... 

Adsorption of adenine and coadsorption of adenine-thymine and uracil-thymine on Au(lll) has been reported [300]. Adenine was chemisorbed in two different states. Mutual interaction between adenine and thymine was detectable only at... 

M. Isaacson, Interaction of 25keV electrons with the nucleic acid bases, Adenine, Thymine, Uracil. II. Inner shell excitation and inelastic scattering cross sections, J. Chem. Phys. 56 (1972) 1813. 

The BFPT process may take place whenever an excess electron is attached to a nucleobase interacting with a proton donor. In particular, the role of a proton donor could be filled by another nucleobase. Especially interesting are complementary base pairs, AT and GC, since these systems appear in DNA. In the case of the adenine-thymine base pair (AT), a combination of three proton donor and acceptor pairs of adenine with three proton donor and acceptor pairs of thymine leads to nine possible, planar, cyclic H-bonded complexes (see Figure 21-22 [49]). 

Considerable attention has also been devoted by several investigators to the theoretical study of the potential curves for hydrogen bonds of the guanine-cytosine and adenine-thymine base pairs. An accurate representation of this potential is important because the genetic code is contained in this interaction. Lowdin has suggested that mutations may be a result of a shift in position of the hydrogen bond protons in the base units of DNA via proton tunneling. " The idea of proton... 

Yet another effect of the action of Ag" has been described, namely, its interaction with nucleic acids [112]. The Ag" ion interacts preferentially with the bases found in DNA rather than with the phosphate group [113-118]. The reaction between Ag and a GC (guanine-cytosine) base pair proceeds via two steps, whereas that between Ag" and an AT (adenine-thymine) base pair requires only one step [116], Ag appears to be attached to the N atom... 

A wide assortment of different possible geometries for the uracil dimer were examined [127] in 1998. The most stable of all these contained a pair of NH- -O bonds, but another was identified, only slightly less stable than the others, in which one of these conventional H-bonds was replaced by CH- -O = C. There was no way of estimating the energetic contribution of this particular interaction, as it was secondary to the stronger NH- -O bond. A study of the adenine thymine pair [128] noted a blue shift of the C-H stretching frequency, an indication of a H-bond, but the authors did not attempt to extract an interaction energy. 

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