Towards a protocol for solution structure determination of copper(II) proteins:: the case of CuIIZnII superoxide dismutase

We have developed an optimized protocol to solve the solution structure of copper(II)) proteins. After assignment, proton-proton NOEs are used for the shell where H-1 spectra are conveniently observed. In a shell closer to the metal ion, C-13 NMR spectra with band-selective homonuclear decoupling provide the assignment of all nuclei except for those of the metal ligands. A convenient method for the measurement of C-13 longitudinal-relaxation rates (R-1) of carbonyls and carboxylate moieties is proposed. H-1 NOES and H-1 and 13 C R, data are sufficient to produce a good/reasonable solution structure, as demonstrated for a monomeric species of superoxide dismutase, a 153-residue protein.