Invisible states in paramagnetic copper proteins studied by NMR

A. J. VILA

Anaheim

Encuentro; 241st ACS National Meeting; 2011

ACS

NMR of oxidized copper proteins has been largely unexplored due to the slow electron relaxation times of Cu2+. However, T1, T3 and CuA centers display relatively fast electron relaxation rates which make them amenable to NMR studies. In the binuclear copper sites CuA and T3, this is due to low-lying excited states that are populated at room temperature and contribute to the reactivity of the metal site. NMR can shed light on these invisible, partially populated, electronic states. The engineering of different axial ligands in CuA tunes the energy gap between the ground state and the invisible excited state, thus providing a mechanism to regulate the electronic structure of the metal site at room temperature. This information nicely complements the picture provided by ground state magnetic techniques such as EPR and ENDOR.