Julia Rendon, Frédéric Biaso, Pierre Ceccaldi, René Toci, Farida Seduk, Axel Magalon, Bruno Guigliarelli, and Stéphane Grimaldi. Inorg. Chem., 2017, 56 (8), pp 4422–4434. DOI: 10.1021/acs.inorgchem.6b03129
Combining multiple isotope-enrichment strategies in 98Mo and 15N nuclei together with EPR, HYSCORE spectroscopy, and DFT modeling, we propose a structural model of the low-pH Mo(V) species in respiratory nitrate reductase that implies coordination of the metal by a monodentate Asp222 ligand and a hydroxyl moiety. Furthermore, we unveil the peculiar involvement of the conserved Asn52 to the H-bond network around the Mo-cofactor in both low- and high-pH species.