(A) Structures of B[c]Ph, (–)-anti-B[c]PhDE, and 1S-(–)-B[c]Ph-dA. Torsion angles α′, β′, and χ are defined as follows: α′, N1–C6–N6–C1(B[c]Ph); β′, C6–N6–C1(B[c]Ph)-C2(B[c]Ph); and χ, O4′–C1′–N9–C4. (B) Human N-ras codon 61 sequence context employed in the MD simulation. * denotes the B[c]PhDE modification site. p and t denote the primer and template strand, respectively. Arrows denote the type I and type II positions for incoming dNTP. dR denotes 2′-deoxyribose.