1.3.1.6	Fe-S cluster	three Fe-S clusters relay electrons over more than 30 A, varying the medial [4Fe-4S] cluster potential over a 100 mV range does not have a significant effect on the inherent kinetics of electron transfer to and from the active-site flavin	
1.3.1.6	Fe2+	enzyme contains 4 bis-His-ligated, c-type hemes, His61 is involved in binding, analysis of crystal structure	
1.3.1.6	Fe2+	heme cofactor	
1.3.1.6	Mg2+	-	
1.3.1.6	Na+	slight activation	
1.3.1.6	Na+	internally bound, coordinated by 1 solvent water molecule and the backbone carbonyl oxygens of residues Thr506, Met507, Gly508, Glu534, and Thr536, structure analysis, His505 is not essential for maintaining the sodium binding site