Refined distances between paramagnetic centers of a multi-copper nitrite reductase determined by pulsed EPR (iDEER) spectroscopy

A new pulse sequence: The distances between copper sites of the homotrimeric Cu-containing nitrite reductase were determined by EPR spectroscopy (see picture). By exploiting the differences in the electron spin relaxation of the Cu ions, a filtering technique allows the selective removal of distances from a complex distance distribution. This filter technique combined with the PELDOR experiment promises to be useful for distance mapping by EPR spectroscopy.