13C{13C} 2D NMR: A Novel Strategy for the Study of Paramagnetic Proteins with Slow Electronic Relaxation Rates

Abstract
Oxidized human [2Fe-2S] ferredoxin has a notably slow electronic relaxation rate, which precludes the observation of signals from nuclei near the iron−sulfur cluster by conventional 2D or 3D methods that utilize proton detection. We have demonstrated the utility of 13C{13C} CT-COSY in identifying connectivity information from fast relaxing carbon nuclei near the paramagnetic center, including those from residues that ligate the metal center.