2D 13C-13C correlation spectra of (a) DsbB/CuDMPE-DTPA (recycle delay 0.3 s, total time 46 h) and (b) DsbB (recycle delay 1.5 s, total time 43 h) under 36 kHz MAS with RFDR 7.1 ms mixing (B0 = 17.6 T, Tsample = −15 °C, maximum t1 = 15.36 ms, maximum t2 = 20.48 ms). The crosspeaks of residues that are resolved in both spectra are marked. Both data were processed with 30 and 30 Hz net line broadening in each dimension and plotted at the same contour levels, with the lowest contour at 5σ.