Figure 4: Paramagnetic R₁ relaxation and conformational exchange of K290A mutant.

a, 1D ¹⁹F spectra of K290A/dHis/M385C-TET GltPh in the absence (left) and presence (right) of Ni²⁺ ions. Raw data are black, fits are magenta and deconvoluted peaks are blue. b, Representative R₁ relaxation traces of S1 (top), S2 (middle) and S3 (bottom) in the absence of Ni²⁺ ions (black), or in the presence of Ni²⁺ and bound to L-asp (red for S1, blue for S2 and S3) or TMA (cyan). Solid lines represent mono-exponential fits with fitted R₁ values shown in Supplementary Table 1. Three independently prepared samples yielded similar results. c, ¹⁹F-¹⁹F EXSY spectra of K290A/dHis/M385C-TET GltPh bound to L-asp (left) or TMA (right). Mixing time was set to 0.4 s. Dashed lines indicate cross peaks for S1 and S2 (dark blue), S1 and S3 (light blue) and S2 and S3 (black). d, R₁ rates of S1, S2 and S3 peaks of K290A/dHis/M385C-TET in the absence (yellow) and presence of Ni²⁺ ions and bound to L-asp (cyan) or TMA (gray). Individual data points are shown and the bars indicate means ± s.d. (N = 3).