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. Author manuscript; available in PMC: 2013 May 23.
Published in final edited form as: J Am Chem Soc. 2012 May 8;134(20):8693–8702. doi: 10.1021/ja3026328

Figure 4.

Figure 4

13C and 15N MAS spectra of GHI-M2TM in the VM+ membrane without Cu(II) (black) and with Cu(II) at the 4:1 Cu(II): tetramer ratio (red). (a) 1D 13C double-quantum filtered spectra detecting only peptide signals. The His37 aliphatic and carbonyl signals are mostly suppressed by Cu(II). (b) Aromatic region of the 1D 13C MAS spectra with and without Cu(II). Except for the lipid signal at 130 ppm (denoted by a star), all imidazole signals are suppressed by Cu(II). (c) Regions of the 2D 13C-13C correlation spectra of GHI-M2TM. Cu(II) binding suppressed the His37 signals and perturbed the Gly34 CO chemical shift. (d) 1D 15N MAS spectra. The His37 Nε2 signal is removed while a small fraction (~10%) of the Nδ1 intensity remains. The two spectra are scaled such that the Nδ1 intensity is matched to show the preferential suppression of the Nε2 peak. No 250-ppm 15N signal is observed, verifying the acidic pH of the samples. The Cu(II)-Nε2 chelated imidazole structure is shown in the box.