(a) Chemical structures of B[c]Ph, B[a]P and DB[a,l]P with designation of bay region for B[a]P, and fjord regions for B[c]Ph and DB[a,l]P. (b) Chemical structures of the 14R (+)- and 14S (–)-trans-anti-DB[a,l]P-N6-dA adducts. The lesion-DNA linkage site torsion angles α′ and β′, glycosidic torsion angle, χ, fjord region twist torsion angle δ′ and benzylic ring pucker torsion angle γ′ are defined as follows: α′, N1-C6-NC14(DB[a,l]P); β′, C6-N-C14(DB[a,l]P)-C13(DB[a,l]P); χ, O4′-C1′-N9-C4; δ′, C15-C19-C24-C1; γ′, C14-C13-C12-C11. (c) The base sequence context in which the lesion is embedded. A6* designates the lesion modified adenine.