Figure 2.

SrcCD SSP NMR chemical shift perturbation and paramagnetic relaxation. (a). Chemical shift perturbation of backbone amide peaks in the trosy‐HSQC spectra of SrcCD between the SSP bound and free states (black bars). Residues whose amide peaks appear only in the peptide‐bound spectrum are shown with red stars. A CSP value greater than 0.05 ppm is a reliable measurement based on linewidths and digital resolution of the spectrum. (b). Perturbation mapped to SrcCD surface for residues with CSP > 0.1 ppm (purple) or resonances observed only in SSP‐bound state (magenta). (c). The ratio of integrated peak volumes measured from HSQC spectra acquired for the oxidized and reduced forms of 3 (2 iodoacetamido) PROXYL plotted against the residue number. (d). PREs calculated from Vox/Vred = exp(−PRE × 2τ_INEPT), where τ_INEPT is the time for which the proton magnetization is transverse during the INEPT transfer sequence in the 15 N trosy HSQC. Residues with higher values of PRE are closer to the spin label. G300, whose amide peak is absent in the spectrum with an oxidized spin label, is shown as a dotted arrow. (e). Volume ratios mapped on the surface of SrcCD in red: Vox/Vred <0.25; green: 0.25 < Vox/Vred <0.50; slate: Vox/Vred >0.50; gray: unassigned residues