Copper(II) proteins are amenable for NMR investigation

The possibility of investigating copper proteins by nuclear magnetic resonance is here treated. It is shown that the solution structure and dynamic information can be obtained on Type I Cu(II) proteins, which have a relatively short electron relaxation time (τS = 10–10 s). The experimental approach, in this case, is routine, although tailored for fastrelaxing nuclei. In the case of Type II Cu(II) proteins, when the electron relaxation times are larger (τS = 10–8–10–9 s) and proton linewidths are broadened beyond detectable limits, heteronuclear 13C spectra with direct detection can be used and the solution structure can again be obtained. In this review, it is shown that Cu(II) proteins are now amenable for NMR investigation, the size being the only limit as in diamagnetic proteins.