Summary of the reactivity of chemical probes with the TGGT(21) (left) and CGGA(21) (right) duplexes containing single, site-specific 1,2-GG intrastrand cross-link of Pt(R,R-DAB)2+ or Pt(S,S-DAB)2+. The reactivity of the chemical probes was evaluated via piperidine-induced specific strand cleavage at KMnO4-modified thymine residues, DEPC-modified adenine and guanine residues, and KBr/KHSO5-modified cytosine residues. (•) and (○) designate strong or weak reactivity, respectively. The data for the duplex TGGT were taken from our article published previously (Malina et al., 2000).