Figure 5.

Aromatic and anomeric regions of ¹H NMR spectra at pH 6.8. (A) The unmodified duplex d(GGTGTCCG)⋅d(CGGACACC) at 10°C. (B) The duplex d(GGTXTCCG)⋅d(CGGACACC) at 10°C. (C) The duplex d(GGTMTCCG)⋅d(CGGATACC) at 10°C. The broadening of the M₁G H6, H7, and H8 resonances was attributed to the low thermal stability of the M₁G⋅T mismatch. An additional source could be conformational exchange of M₁G about the glycosyl bond, as observed for its saturated analog PdG (38). (D) The duplex d(GGTXTCCG)⋅d(CGGACACC) at 50°C after thermal denaturation. (E) The duplex d(ATCGCXCGGCATG)⋅d(CATGCCGCGCGAT) at 10°C. (F) The duplex d(ATCGCXCGGCATG)⋅d(CATGCCGCGCGAT) after thermal denaturation.