Figure 4

The B-helix conformation of dsDNA determined by J-coupling constants of ³J_{H1′–H2′} (>10 Hz) in 2D NMR ¹H-¹H DQF-COSY spectra (right). The assignments of the cross-peaks H1′-H2′ of each residues in the DNA sequences were performed based on the spin system identification in ¹H-¹H TOCSY and NOE intensity differences between the cross-peaks of H1′-H2′ and H1′-H2″ in ¹H-¹H NOESY spectrum. Here, we used the assignments of H1′-H2′ of residues G2 and G16 as examples. (A) [R_p, R_p]-PT dsDNA, (B) [S_p, S_p]-PT dsDNA and (C) PT-free dsDNA. The assignments of all H2′ and H2″ protons in sugar ring were performed based on the spin system identification through 2D NMR ¹H-¹H TOCSY spectra (left) and confirmed by the intensity of NOE cross peaks between H1′ and H2′ or H2″, observed in 2D NMR ¹H-¹H NOESY spectra (middle).