NMR Crystallography as a Novel Tool for the Understanding of the Mode of Action of Enzymes: SOD a Case Study

Nuclear magnetic resonance (NMR) crystallography is an approach for revealing molecular and supramolecular structures and molecular packing for systems where standard X-ray crystallography gives no results. It combines solid-state NMR techniques with chemical models and/or molecular dynamics and/or quantum chemical calculations. These techniques are often supported by other structure characterization methods. In the present review, recent results on the application of NMR crystallography for the investigation of the mode of action of superoxide dismutases are discussed. Studies of substrate–inhibitor complexes of human manganese and Streptomyces nickel superoxide dismutase are presented, which are chemical models of the transient enzyme–substrate complex. The review is completed by new, previously unpublished results, calculating an NMR structure of NiSOD model peptide-bound cyanide based on experimental restraints measured by us and derived from the literature and extended DFT calculations.