Solid-state 17 O NMR Study of Small Biological Compounds

We present a systematic experimental and theoretical investigation of the oxygen chemical shielding and electric-field-gradient tensors in polycrystalline amino acids and a peptide. Analysis of the 17 O magic-angle-spinning (MAS), multiple-quantum MAS, and stationary nuclear magnetic resonance (NMR) spectra yield the magnitudes and the relative orientations between the two NMR tensors. The obtained 17 O NMR parameters are sensitive to the hydrogen bond environments. We also demonstrate that solid-state 17 O NMR is potentially useful for studying the secondary structures of peptides and proteins.