Nucleobases structure

Murata T, Nishimura K, Saito G (2007) Organic conductor based on nucleobase structural and electronic properties of a charge transfer solid composed of TCNQ anion radical and hemiprotonated cytosine. Mol Cryst Liq Cryst 466 101-112... 

Geyer, C.R., Battersby, T.R., and Benner, S.A. 2003. Nucleobase pairing in expanded Watson-Crick-like genetic information systems. The nucleobases. Structure 11 1485-1498. 

Figure 16-1. DNA and RNA nucleobases structure and labeling with their conventional name and, within parentheses, the IUPAC name and the abbreviation...

Fig. 4.1 Spin densities of a guanine-cytosine dimer radical cation, (GC)j. a KS-DFT supramole-cular calculation using PW91 functional, b FDE calculation considering two subsystems where the left side subsystems blue contour) is positively charged and c FDE calculation for four subsystems with one subsystems blue contour) is positively charged. The nucleobases structures and spin densities were taken from Ref. [48]...

Fig. 1. Elements of DNA/RNA primary structure. (A) backbone units, (B) nucleobase structures, (C) glycosidic bond rotation interconverts syn and anti conformations, and (D) preferred sugar puckers for deoxyribose (left) and ribose (right).

The following section deals with modifications to oligonucleotides dealing with modifications to the internucleotide linkage, the sugar and the nucleobase as separate sections. As in previous years the modification to the nucleobase remains the major part of this review as the number of alternate nucleobase structures continues to increase. In addition there are many un-natural nucleobases described aimed at introducing some particular functionality into oligonucleotides or for the introduction of some spectral property. 

However both classes, nucleic acids and proteins, are linear polymers in which the linear (nucleobase or amino acid) sequence encodes the three-dimensional structure and function of the polymer. 

The crystal and molecular structure of the 44, 45, and C5-vinylferro-cenyl-thymidine show that the substituted cyclopentadienyl ring is essentially co-planar with the nucleobase (164). DFT calculations indicate that, irrespective of the extent of saturation in the bridging C2-unit in ethynyl-, vinyl- or ethyl-ferrocenyl-C5-thymidine, a similar amount of spin density is transferred to the nucleobase (Fig. 48). The reduction potentials for these compounds are shifted little compared to the parent ferrocenyl derivatives. 

Scheme 1 Structures of the Sa and Sd hairpin linkers, electron donor nucleobases and their oxidation potentials, and the hairpins 3G and 3GAGG shown in Fig. 1...

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