Figure 2.

(A) Arrangement of the large and small subunit in E. coli Hyd-1, a member of Group 1 [NiFe] hydrogenases, PDB code 3USE. Variability in structure and coordination of the proximal cluster in [NiFe] hydrogenases: (B) E. coli Hyd-1 oxidized [4Fe-3S] cluster with 6Cys coordination (PDB code 3USC); (C) regular [4Fe-4S] cluster with all-cysteine coordination in the periplasmic hydrogenase from Desulfovibrio gigas (PDB code 1YQ9); and (D) [4Fe-4S] cluster with Asp-3Cys coordination in the actinobacterial-type hydrogenase from Ralstonia eutropha (PDB code 5AA5). Prepared using Pymol.⁷