Guanine-adenine complex

Fig. 20.3 The total intermolecular interaction energy and the first-order electrostatic interaction for 54 structures of guanine-adenine complex...

Since nucleic acids and enzymes play such a large role in chromosome replication during mitosis, a considerable amount of research has been conducted in this area to control viruses. On the molecular level, analogues of nucleic acids are capable of forming complexes with adenine, cytosine, uracil, thymine, and guanine. Through complexation, these nucleic acid analogues are potential inhibitors of biosyntheses that require nucleic acids as templates. 

Contrary to H-bonded nucleic acid base pairs discussed in the previous section, the nature of intermolecular interactions in complexes of stacked bases was analyzed more extensively. The values of minimal, maximal, and average total stabilization energies, corrected for BSSE, for a set comprising over 80 stacked bases, are plotted in Fig. 20.1. In the case of guanine-adenine and adenine-cytosine complexes, the results are presented for two sequence contexts, i.e., A/G-G/A and A/C-C/A. The symbol AA denotes the 2-oxo-adenine - complexes of oxidized bases, and this... 

Fig. 22. The complexation induced shifts of the energies of the lowest excitations of nucleic acid bases in the dimers. Shifts are calculated with respect to the free molecule (guanine or cytosine in the guanine-cytosine complex and adenine or thymine in the adenine-thymine complex). For each monomer four excitations are given singlet-singlet A , singlet-singlet A , singlet-triplet A , and singlet-triplet A . Data taken from [Wesolowski, J. Am. Chem. Soc., 126, (2004) 11444].

There is a comparatively rich literature on Cu complexes with nucleic acid bases and nucleotides. Mono- and bis-adenine complexes with Cu exhibit N7 coordination (Figure 14)7 as does the bis-guanine complex." With cytosine, both N3 and 02 positions are found to coordinate Cull 80,81 [Cu (NH3)2] has also been observed in square planar geometry bound to... 

Several square planar Pt complexes with bases, nucleosides, and nucleotides have been characterized. A series of guanine-derived complexes have been prepared with both cis- and trani-geometries. These complexes generally show Pt coordination to the N7 position except when that position is blocked and coordination to the N1 position can be observed. In the case of adenine, Pt coordination to both N7 and N1 is feasible. The crystal structure of bis-adenine Pt bound to the N7 position with irans-geometry has been reported. The mono-, bis-, and tris-cytosine Pt complexes all exhibit coordination to the N3 position. " " A number of mixed-base compounds have been prepared. ... 

Complexes of pentahydrated Zrf with guanine, adenine, and the guanine-cytosine and adenine-thymine base pairs. Structures and energies characterized by polarizable molecular mechanics and ab initio calculations "... 

MP2/6-31G calculations were performed for bonded and stacked structures of adenine-2,4-difluorotoluene complexes 152 [99CPL393] and for adenine with guanine or thymine [97JPC(B)3846]. Classical base pair structures of 152... 

There have been few reports of purine derivatives1 that contain metal-carbon nucleobase binding (75), and those that have been described are often polymetalated (84). Quite recently mononuclear complexes of adenine and guanine have been prepared that contain... 

The mechanism of action of alkylating agents is complex. Adenine and guanine are easily alkylated. Guanine is alkylated primarly at position 7 and adenine at position 3. The reaction produces an exceedingly labile glycosidic bond. Splitting of this bond leads to depurination. 

The complexity of the HCN oligomerisation reaction was also studied by Schwartz et al. (1984) in Nijmegen. The reactions worked best at a pH value which lies near the pK value of HCN. A list of the products of oligomerisation includes 38 compounds, including orotic acid, adenine, guanine and glycine, as well as more complex molecules such as isoleucine, glutamic acid, diaminosuccinic acid and... 

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