Figure 3.

Selected region of the pure absorption NOESY spectrum of the non-exchangeable protons in the duplex formed between d(CCATAATTTACC) and d(CCTATTAAATCC), recorded in 99.9% ²H₂O at pH 5.5. This sub-spectrum shows self and sequential NOE cross-peaks between the sugar H2′, H2″ and CH₃ protons and the base H2/H6/H8 protons. The assignment of various peaks was completed following the standard procedure and the walk steps are indicated in the figure. Experimental parameters were as follows: τ_m = 200 ms, recycle delay 1 s, 64 scans/t₁ increment, time domain data points of 600 and 4096 in the t₁ and t₂ dimensions, respectively. The ¹H carrier frequency was kept at the water resonance. The data were multiplied by sine bell window functions shifted by π/4 and π/8 along the t₁ and t₂ axes, respectively, and zero filled to 1024 data points in the t₁ dimension prior to 2D-FT. The digital resolution along the ω₁ and ω₂ axes correspond to 5.8 and 1.5 Hz/point, respectively.