FIGURE 3.

Saturation transfer difference (STD)-NMR of YrdC with unmodified ASL^Lys_UUU (A) and unmodified ASL^Val3_UAC (B). For each set of experiments, there is a one-dimensional NMR reference spectrum (top) and a STD spectrum of recovered signals (bottom). The spectral region shown displays the characteristic RNA chemical shifts for the aromatic protons (8.5 to 6.5 ppm) and the ribose protons (6.0 to 5.0 ppm). The STD-NMR spectrum records the proton signals from those residues of the ASL that have been bound by YrdC. The standard one-dimensional ¹H-NMR recapitulate previously published data for the unmodified ASL^Lys_UUU (Stuart et al. 2000) and unmodified ASL^Val3_UAC (Vendeix et al. 2008).