Fig. 27. Differential base stacking at the cross-linking region explains the difference in stabilities of the trimethylene-N2-dG:N2-dG interstrand cross-links in the 5′-CpG-3′ vs. the 5′-GpC-3′ sequences, and, in turn, accounts for the same sequence selectivity of interstrand cross-link formation induced by the enal-derived 1,N2-dG adducts.
a) and b) show base stacking in the 5′-CpG-3′ sequence; c) and d) show base stacking in the 5′-GpC-3′ sequence. This illustration was prepared from PDB entries 2KNK and 2KNL using PyMol software [39] (© 2009 American Chemical Society).