Oligonucleotides, platinum binding

Oligomers, condensation, in formation of hy-droxo-bridged complexes, 32 91 Oligonucleotides, platinum binding, 37 185-187... 

After this brief introduction, the chapter will focus on solvolysis reactions and acid-base equilibria of various platinum compounds and on species distribution of isomeric [PtCl2(NH3)2] in aqueous solution in Section 2. Binding of platinum compounds to monomeric nucleobase derivatives will be discussed in Section 3, while Section 4 pays attention to the reactions of Pt-nucleobase complexes with different nucleophiles. And finally, the interactions of Pt with DNA and defined oligonucleotides will be discussed in Section 5. 

Studies with aqua species of Ni11 showed a marked preference for G-rich oligonucleotides (K0 2 X 105 M 1 for poly(dG)-poly(dC)), an association that is actually followed by the reversible binding of nickel to a G-N(7) [88], This case can be considered as intermediate between that of Mg11 and that of the aqua platinum(II) complexes which will irreversibly bind to a guanine after outer-sphere association. The corresponding kinetic equation can be written as in Scheme 3. The formation of the outer-sphere association is likely to be diffusion controlled in solution, in vitro. The coordination step (k) should be rate-determining [95]. 

Luminescent cyclometalated platinum(II) and gold(III) complexes [Pt(dpp-CNN)(MeCN)]+/ [Pt2(pby-CNN)2 (dppm)] +, and [Au(4-MeOPh-Phbpy)Cl] have been prepared and their interactions with calf thymus DNA and synthetic oligonucleotide duplexes poly(dG-dC)2 and poly(dA-dT)2 have been investigated. An intercalative binding mode was proposed for these complexes. 

The interactions of platinum complexes with DNA, oligonucleotide sequences and constituent bases give a detailed description of the binding and contribute to the understanding of the molecular mechanism of action of cisplatin. 

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