NMR crystallography of amides, peptides and protein-ligand complexes

NMR crystallography, the combination of solid-state NMR techniques, chemical modelling, quantum chemical calculations and other characterization techniques, allows the determination of molecular and supramolecular structures which are not amenable to standard X-ray crystallography. The method is demonstrated on a set of application examples. First the principles and practical considerations of NMR crystallography based on dipolar NMR spectroscopy are outlined in conformational studies of polymorphs of N-octyl-gluconamide and of methoxycarbonyl urea. Then structural studies of two substrate-inhibitor complexes, human manganese superoxide dismutase with azide and nickel superoxide dismutase with cyanide, are reviewed. Finally an example of ongoing developments in the related field of EPR crystallography is reported