Figure 2.

a) ¹H_ϵ‐¹⁵N_ϵ and b) ¹³C_ζ‐¹⁵N_ϵ NMR spectra and chemical shift assignments of the arginine side‐chains: Nucleotide‐free UmpK (green), UmpK in complex with AP₅U (red), and UmpK in complex with the TSA (blue). A detailed description of the assignment strategy is given in Supporting Information (see also Figure S3). The resonance assigned to R42 in the TSA ¹³C_ζ‐¹⁵N_ϵ spectrum is folded and therefore appears in yellow. c) Deviation of the assigned ¹⁵N_ϵ and ¹³C_ζ chemical shifts from random coil values. Shown is the $\bar{\omega }$ _RMSD $=\sqrt{1/2\sum {({\delta }_i-{\delta }_{\mathrm{R}\mathrm{C},i})}^2/{\sigma }_{\delta }^2}$ , where δ _i is the assigned chemical shift, δ _RC,i is the random coil chemical shift, and σ is its standard deviation (from the BMRB database).