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	674169	
1.3.1.6	Fe2+	enzyme contains 4 bis-His-ligated, c-type hemes, His61 is involved in binding, analysis of crystal structure	654680	
1.3.1.6	Fe2+	heme cofactor	656728	
1.3.1.6	Mg2+	-	656728	
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	654657	
1.3.1.6	Na+	slight activation	390839