Figure 1.

(A) Chemical structure of the OTB-dG adduct. Green wavy bonds represent the 5′ and 3′ sites where the adduct is linked to the DNA backbone. Torsion angles χ at the sugar–nucleobase linkage and θ at the nucleobase–substituent linkage are defined as follows: χ = ∠(O4′–C1′–N9–C4) and θ = ∠(N9–C8–C10–C11). The OTB-dG adduct can exist in neutral (non-ionized), monoanionic (carboxylic group ionized) and dianionic (carboxylic and phenolic groups ionized) forms. (B) The 12mer NarI recognition sequence used for MD simulations, where the OTB–dG lesion was incorporated at the G¹, G² or G³ position.