Orientation-selected 15N-HYSCORE detection of weakly coupled nitrogens around the archaeal rieske [2Fe-2S] center

The weakly coupled 15N atoms around a reduced Rieske 2Fe-2S] cluster of the uniformly 15N-labeled, hyperthermostable archaeal Rieske protein appear to produce readily observable cross-peaks in the HYSCORE spectra, with the well-resolved couplings of 0.3-0.4 MHz for the Nepsilon and 1.1 MHz for the peptide backbone nitrogens, in addition to the contributions from the coordinated Ndelta atoms. These features can be used for structure-mechanism studies of the biological redox protein system involving the weakly coupled nitrogens in coupled electron-proton transfer reactions.