Copper(II) proteins are amenable for NMR investigations

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 (tau(S) = 10(-10) s). The experimental approach, in this case, is routine, although tailored for fast-relaxing nuclei. In the case of Type 11 Cu(II) proteins, when the electron relaxation times are larger (tau(S) = 10(-8)-10(-9) s) and proton linewidths are broadened beyond detectable limits, heteronuclear C-13 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.