Advanced 500

All NMR experiments were performed at 25 °C using a Bruker Advanced 500 or 800 MHz spectrometer equipped with Cryo probes. A 0.5 mM c-Myc_370–409 sample in 5 mM PBS, pH 6.3, 90% H₂O, 10% D₂O buffer was prepared for backbone and side-chain ¹H resonance assignment using ¹H-¹H NOESY and TOCSY experiments. Samples containing 0.1 mM c-Myc_370–409 in the absence and presence of 0.2 mM PKUMDL-YC-1205 were prepared in 5 mM PBS, pH 6.3, 1% DMSO-d₆, and 99% D₂O. Samples containing 2 mM PKUMDL-YC-1205 with or without 0.04 mM cMyc_370–409 were prepared in DMSO-d₆ for STD NMR experiments.
TOCSY spectra were acquired with a relaxation delay of 1.5 s, 60 ms TOCSY mixing time. NOESY spectra were acquired with a relaxation delay of 2 s, 150 ms NOESY mixing time. All experiments used shaped pulses for water suppression, and the 2D spectra were processed by Bruker^® Topspin software to 2048 × 1024 points and analysed by CcpNmr software53 (link).
STD NMR experiments were performed with a train of 50 ms Gaussian-shaped saturating pulses at 140 Hz power for 3 s with “on” resonance saturation at 0.84 ppm and “off” resonance saturation at 30 ppm. (The relaxation delay was 2 s before the saturating pulses.) The number of scans was 32768 and the spectral width was 16 ppm. STD NMR Spectrum was recorded using a Bruker Advanced 500 spectrometer equipped with Cryo probes and processed by Bruker^® Topspin software.