NMR Data Collection and Analysis Protocols

1D and 2D NMR data collection and analysis were performed as described previously.^{13 (link), 14 (link)} Briefly, all NMR spectra were collected on a Bruker Avance DRX 500 MHz spectrometer equipped with a 5-mm triple-resonance (¹H, ¹³C, ¹⁵N), Z-axis gradient cryoprobe. Automated data collection utilized a Bruker ATM unit for automatic tuning and matching, a BACS-120 sample changer and Bruker Icon NMR software. The 1D ¹H NMR spectra were collected using excitation sculpting for water suppression.^{15 (link)} Six replicates were acquired at 298.15 K with 128 scans, 16K data points, 16 dummy scans, a relaxation delay of 1.5 s, a spectral width of 5000 Hz, and a total acquisition time of approximately 7 minutes. 2D ¹H-¹³C HSQC NMR spectra were collected at 298.15 K with 128 scans and a relaxation delay of 1.5 s. The spectra were collected with 2K data points and a spectrum width of 5,000 Hz in the direct dimension, and 64 data points and a spectrum width of 17,605.6 Hz in the indirect dimension, and a total acquisition time of approximately 4 hours. The 2D ¹H-¹³C HSQC NMR spectra were processed in NMRPipe and analyzed with NMRViewJ version 9.^{16 (link), 17 (link)}