Solid-state nuclear magnetic resonance structural studies of proteins using paramagnetic probes

► Review of MAS solid-state NMR studies of proteins containing paramagnetic centers. ► Paramagnetic probes enable measurements of electron-nucleus distances up to ∼20Å. ► Paramagnetic restraints are applicable to protein structure determination. ► Paramagnetic species facilitate condensed solid-state NMR data collection. ► Paramagnetic species allow analysis of solvent-accessible surfaces in biomolecules.