How does cisplatin alter DNA structure? A molecular mechanics study on double-stranded oligonucleotides.

Molecular models for two double-stranded decanucleotides, d(GCCG*G*ATCGC)-d(GCGATCCGGC) (1) and d(GCTG*G*ATCGC)-d(GCGATCCAGC) (2), with the G* guanines cross-linked by a cis-Pt(NH3)2 moiety, were calculated using molecular mechanics. Nine models for 1 and eight models for 2 are reported; in all of them, the double helix is kinked by approx. 60 degrees towards the major groove and slightly unwound. The model building has been guided by comparison with the NMR data available for duplex 1. The influence of the base at the 5'-side of the coordinated G*G* dinucleotide is discussed.