1.8.7.3	FAD	-	744307	
1.8.7.3	FAD	required for activity. Conformational changes within the HdrA subunit provide a conformationally gated pathway for electrons to and from the bifurcating flavin adenine dinucleotide (FAD)	765833	
1.8.7.3	FAD	the enzyme is an iron-sulfur subunit A of the HdrABC complex and contains [4 Fe-4S] clusters	764472	
1.8.7.3	FAD	the multisubunit enzyme complex is composed of a dimer of two HdrABC-MvhAGD heterohexamers with a flavin-containing HdrA dimer in the center, to which two catalytic arms, MvhAGD and HdrBC, are attached	765831	
1.8.7.3	Fe-S center	subunits HdrB of heterodisulfide reductase (HdrABC-MvhAGD) contains two noncubane [4Fe-4S] clusters used for reduction activity. The two noncubane [4Fe-4S] clusters are composed of fused [3Fe-4S]-[2Fe-2S] units sharing 1 iron (Fe) and 1 sulfur (S), which are coordinated at the CCG motifs. The N-terminal domain has a fold similar to MvhD but contains, instead of a [2Fe-2S] cluster, a [4Fe-4S] cluster (HA3) that is unusually ligated by five cysteines	765831	
1.8.7.3	Fe-S center	subunits HdrB of heterodisulfide reductase (HdrABC-MvhAGD) contains two noncubane [4Fe-4S] clusters used for reduction activity. The two noncubane [4Fe-4S] clusters are composed of fused [3Fe-4S]-[2Fe-2S] units sharing 1 iron and 1 sulfur, which are coordinated at the CCG motifs. The N-terminal domain has a fold similar to MvhD but contains, instead of a [2Fe-2S] cluster, a [4Fe-4S] cluster (HA3) that is unusually ligated by five cysteines	765831	
1.8.7.3	Ferredoxin	-	764472, 764654, 764753, 765833	
1.8.7.3	additional information	the enzyme contains (4Fe-4S)clusters	765833	
1.8.7.3	additional information	the HdrABC·MvhAGD (see also EC 1.8.98.1) complex is abundant in iron-sulfur cofactors, with 11 [4 Fe-4S] clusters, one [2 Fe-2S], a Ni-Fe site for H2 catalysis, and two noncubane iron-sulfur clusters	764472	
1.8.7.3	additional information	the thioredoxin reductase domain of HdrA (145 to 236 and 315 to 567) resembles thioredoxin reductase in the fold and geometry of the FAD-binding site but forms a completely different dimer interface, owing to the perpendicular position of the respective two-fold axes. The thioredoxin-reductase domain of HdrA has, in addition, a [4Fe-4S] cluster (HA4) that is surrounded by several basic residues and coordinated with a Cys386, Cys399, Cys403, and Cys404 sequence motif (consensus sequence CX10-16-Y/W/H/F-C-S/A/C-X2-3CC)	765831