CO as a Substrate and Inhibitor of H+ Reduction for Mo-, V-, and Fe-Nitrogenase Isozymes

Alignment of α subunits of nitrogenase isozymes. Shown is<br> an alignment of α subunits of Mo-nitrogenase (PDB ID: 3U7Q), V-nitrogenase<br> (PDB ID: 5N6Y), and Fe-nitrogenase (sequence threaded<br> on to V-nitrogenase PDB ID: 5N6Y using Swiss-Model) highlighting<br> amino acid residues in the cofactor environment. The starting perspective is<br> looking down on the Fe2, 3, 6, 7 face of FeMoco and FeVco. S is in<br> yellow, Fe in orange, Mo in magenta, and V in pink with the homocitrate<br> to the right in grey. Side chains that are 100% conserved among the<br> isozymes are shown in green, whereas side chains where there is<br> variation in the residue in at least one isozyme are shown in red. The residue numbering refers<br> to Mo-nitrogenase. ChimeraX version 1.0 file.