Figure 3. One-dimensional NMR of the Cu(PrP^57–91) complex.

The Cu(PrP^57–91) complex can be observed by one-dimensional ¹H-NMR. The given region of the spectra shows the aromatic histidine and tryptophan signals for a titration of 30 μM peptide with copper bisglycinate, in 25 mM phosphate buffer, pH 7.4. The mole fraction of copper added is shown on the left. Signals from the four histidine residues in the octapeptide repeats are overlapped so only combined signals are observable. Addition of copper causes specific broadening of the two histidine imidazole signals, with reduced broadening observed for the tryptophan indole signals.