Structural characterization of insoluble proteins often relies on solid-state NMR spectroscopy. Perdeuteration and partial back-substitution of exchangeable protons, as proposed for crystalline model proteins, is now shown to lead to beneficial proton spectra for heterogeneous systems, such as fibrils formed by the Alzheimer's disease β-amyloid peptide Aβ40, the lipid reconstituted β-barrel membrane protein OmpG, and the α-helical membrane protein bacteriorhodopsin.