(A) Chemical structure of cisplatin. (B) Overall structure of DNA duplex (5′-CCTCTG*G*TCTCC-3′ and 5′-GGAGACCAGAGG-3′) in complex with cisplatin (PDB ID: 1AIO). (C) Close view of G*G* platination sites. The base pairs are propeller-twisted, but retain the hydrogen-bonding interactions. (D) Superimposition of the low-resolution structure (PDB: 1AIO) and high-resolution structure (PDB: 3LPV) of DNA duplexes modified with a 1,2-cis-{Pt(NH3)2}2+-d(GpG) cross-links. The DNA is shown as sticks, the N and Pt atoms are shown as the cyan and red spheres in 1AIO, and the yellow and red spheres in 3LPV, respectively.