Transient nuclear Overhauser effect (NOE) experiments were made with bovine Cu,Co Superoxide dismutase on the hyperfine shifted resonances of protons of the imidazole groups bound to the Cu.Zn cluster of the native enzyme. Assignments of lines based on the observed magnetization transfers were satisfactorily obtained only by altering the arrangement of the ligands around the catalytically active copper shown by X-ray crystallography.
