Figure 2.

1D and 2D NMR spectra of ETR in the DMPC: DMPG membrane. (a) ¹³C cross-polarization (CP) and direct-polarization (DP) spectra of ETR (black) at 305 K and 275 K. The CP spectra preferentially detect immobilized residues whereas the DP spectrum preferentially detects mobile residues. The CP spectrum of ETM (orange) is also shown for comparison. (b) 2D NC spectrum of ETR (blue) measured at 305 K, overlaid with the ETM spectrum (orange) for comparison. ETR assignments obtained from 3D correlation spectra are indicated. (c) 2D CC spectrum of ETR (blue) measured at 305 K, overlaid with the ETM spectrum (orange). β-sheet chemical shifts are observed for residues such as Ser and Val, which are absent in the ETM spectrum.