Figure 3.

Small regions of the 600 MHz (A) forward and (B) reverse sampled 2D ¹H-¹³C′ HNCO spectra of a sample containing 125 μM ¹⁵N/¹³C′/²H-VA2-ubiquitin, pH 6.4, 25 °C. Full spectra are shown in Figures S7 and S8. Fully analogous to the spectra of Figure 2, the forward spectrum (A) primarily shows F₁ dimension correlations for unfolded protein, correlated to 2.5 kbar ¹H F₂ frequencies of either folded or unfolded protein. Analogously, the reverse sampled spectrum (B) shows in the F₁ dimension the 1-bar ¹³C′ frequencies of U, I, and F species, correlated with 2.5 kbar ¹H frequency of the amide of the next residue. Each peak number indicates the residue that is ¹³C′ labeled, with the first superscript referring to the state of the protein during ¹³C′ evolution at 1 bar, and the second superscript denoting the state during ¹H detection at 2.5 kbar.