Nucleobases, metal-nucleobase chemistry

Instead, this review seeks to cover less well-known and newly emerging aspects of metal-nucleobase chemistry. In addition to biomedical relevancies, nucleic acid chemistry offers a paradigm for organizing molecules via base pairing. Combining the hydrogen bonding... 

N7H = 11.57 ppm). While these reactions are rather unusual with regard to metal-nucleobase chemistry, they are in fact examples of classical cyclometalation (97). Such reactions often involve a pre-coordination step, as observed in the formation of 25. 

New Aspects of Metal-Nucleobase Chemistry Andrew Houlton... 

Attempts to model the intrastrand d(GpG) crosslink with nucleobases have met with only moderate success. Usually the 06 atoms of the two guanosine rings are on opposite sides of the platinum coordination plane ( head-to-tail isomer). Only for cw-[Pt(NH3)2(9-EtG)2] was the correct isomer obtained. Nucleobase complexes of the ds-diammineplatinum(II) moiety have been valuable for testing the controversial proposal of N7,06 chelate formation, which to date has not been observed. Several interesting discoveries of metal-nucleobase chemistry are that metal binding can stabilize rare tautomers, for example, the... 

The preceding discussion has emphasized studies of binding sites and thermodynamic/kinetic considerations. An area of interest, which is now receiving as much attention as the structural aspects, is the reactivity of the bases upon metallation. The principal points of nucleobase chemistry modified by metallation which have been studied are ... 

These points all refer to alteration of the inherent chemistry of the bases, which, although not emphasized in relation to platinum metal complexes and their antitumour activity, is a recognized lesion which may lead to cell kill through inhibition of DNA synthesis. Further features of metal—nucleobase chemistry are the dynamic features of... 

Another question related to the dynamics of platinum—nucleobase chemistry is the rotational freedom or otherwise of the metal—purine bonds. This point is relevant to the formation of, for instance, an intrastrand link upon binding of the platinum to the first base. Studies on the cis-[Pt(NH3)2(Guo)2] cation indicated little restriction around the Pt—purine bond [65, 66] but with bulkier ligands (A, A-Me2-en, N,N,N N -Mq - vl) restricted rotation is observed [65,67]. 

While metal-nitrogen and metal-oxygen bonded compounds dominate nucleobase coordination chemistry, examples in which metal-carbon bonds are formed have been identified. Early studies on the synthesis of metal-labeled DNA demonstrated that nucleotide-triphosphates, UTP, CTP, dUTP, and dCTP, can undergo mercury modification at C5 (82,83). The UTP derivative was also shown to act as a substrate for RNA polymerase in the presence of mercaptans (83). Later, guano-sine was shown to undergo mercury modification at C8 though, in this case, the purine was multiply substituted, 21 (84). 

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