1.6.1.4 FAD - 288551, 742880 1.6.1.4 FAD iron-sulfur flavoprotein complex. Subunit NfnB contains FAD 731998 1.6.1.4 iron-sulfur centre iron-sulfur flavoprotein complex, subunit NfnA has a predicted [2Fe2S] binding site, subunit NfnB has two predicted [4Fe4S] binding sites. UV-visible spectrum shows that the NfnAB complex contains up to 10 Fe molecules per heterodimer, which is consistent with the presence of two [4Fe4S] and one [2Fe2S] clusters 731998 1.6.1.4 iron-sulfur centre - 742779 1.6.1.4 flavin flavoprotein 745371 1.6.1.4 FAD the 31000 Da subunit contains one FAD (S-FAD) and a [2Fe-2S] cluster with an unusual Asp ligand. The 53000 Da subunit contains one FAD (L-FAD), which is the site of electron bifurcation, and two [4Fe-4S] clusters. The L-FAD proximal [4Fe-4S] cluster coordination includes an unusual Glu ligand. S-FAD and L-FAD bind NADH and NADPH, respectively 745843 1.6.1.4 [2Fe-2S]-center the 31000 Da subunit contains one FAD (S-FAD) and a [2Fe-2S] cluster. The [2Fe-2S] cluster is unusual, with a relatively high (positive) reduction potential and coordination by one Asp and three Cys ligands 745843 1.6.1.4 [4Fe-4S]-center the 53000 Da subunit contains one FAD (L-FAD), which is the site of electron bifurcation, and two [4Fe-4S] clusters 745843