| B | Oxidored_q6 | e3ayzB2 | A: a/b three-layered sandwiches | X: Flavodoxin-like | H: Class I glutamine amidotransferase-like | T: CheY-like | F: Oxidored_q6 | ECOD (1.6) |
| B | NiFe_hyd_SSU_C | e3ayzB1 | A: few secondary structure elements | X: Fe-S cluster-binding domain in nickel-iron hydrogenase small subunit (From Topology) | H: Fe-S cluster-binding domain in nickel-iron hydrogenase small subunit (From Topology) | T: Fe-S cluster-binding domain in nickel-iron hydrogenase small subunit | F: NiFe_hyd_SSU_C | ECOD (1.6) |
| D | Oxidored_q6 | e3ayzD2 | A: a/b three-layered sandwiches | X: Flavodoxin-like | H: Class I glutamine amidotransferase-like | T: CheY-like | F: Oxidored_q6 | ECOD (1.6) |
| D | NiFe_hyd_SSU_C | e3ayzD1 | A: few secondary structure elements | X: Fe-S cluster-binding domain in nickel-iron hydrogenase small subunit (From Topology) | H: Fe-S cluster-binding domain in nickel-iron hydrogenase small subunit (From Topology) | T: Fe-S cluster-binding domain in nickel-iron hydrogenase small subunit | F: NiFe_hyd_SSU_C | ECOD (1.6) |
| C | NiFeSe_Hases_2nd | e3ayzC1 | A: beta meanders | X: all-beta domain in nickel-iron hydrogenase large subunit (From Topology) | H: all-beta domain in nickel-iron hydrogenase large subunit (From Topology) | T: all-beta domain in nickel-iron hydrogenase large subunit | F: NiFeSe_Hases_2nd | ECOD (1.6) |
| C | NiFeSe_Hases_1st | e3ayzC2 | A: alpha complex topology | X: alpha-helical domain in nickel-iron hydrogenase, large subunit (From Topology) | H: alpha-helical domain in nickel-iron hydrogenase, large subunit (From Topology) | T: alpha-helical domain in nickel-iron hydrogenase, large subunit | F: NiFeSe_Hases_1st | ECOD (1.6) |
| C | NiFeSe_Hases_3rd | e3ayzC3 | A: a+b two layers | X: FAD-linked reductases, C-terminal domain-like | H: Ni-Fe binding domain in nickel-iron hydrogenase large subunit (From Topology) | T: Ni-Fe binding domain in nickel-iron hydrogenase large subunit | F: NiFeSe_Hases_3rd | ECOD (1.6) |
| C | NiFeSe_Hases_3rd_1 | e3ayzC4 | A: a+b two layers | X: FAD-linked reductases, C-terminal domain-like | H: Ni-Fe binding domain in nickel-iron hydrogenase large subunit (From Topology) | T: Ni-Fe binding domain in nickel-iron hydrogenase large subunit | F: NiFeSe_Hases_3rd_1 | ECOD (1.6) |
| A | NiFeSe_Hases_2nd | e3ayzA1 | A: beta meanders | X: all-beta domain in nickel-iron hydrogenase large subunit (From Topology) | H: all-beta domain in nickel-iron hydrogenase large subunit (From Topology) | T: all-beta domain in nickel-iron hydrogenase large subunit | F: NiFeSe_Hases_2nd | ECOD (1.6) |
| A | NiFeSe_Hases_1st | e3ayzA2 | A: alpha complex topology | X: alpha-helical domain in nickel-iron hydrogenase, large subunit (From Topology) | H: alpha-helical domain in nickel-iron hydrogenase, large subunit (From Topology) | T: alpha-helical domain in nickel-iron hydrogenase, large subunit | F: NiFeSe_Hases_1st | ECOD (1.6) |
| A | NiFeSe_Hases_3rd | e3ayzA3 | A: a+b two layers | X: FAD-linked reductases, C-terminal domain-like | H: Ni-Fe binding domain in nickel-iron hydrogenase large subunit (From Topology) | T: Ni-Fe binding domain in nickel-iron hydrogenase large subunit | F: NiFeSe_Hases_3rd | ECOD (1.6) |
| A | NiFeSe_Hases_3rd_1 | e3ayzA4 | A: a+b two layers | X: FAD-linked reductases, C-terminal domain-like | H: Ni-Fe binding domain in nickel-iron hydrogenase large subunit (From Topology) | T: Ni-Fe binding domain in nickel-iron hydrogenase large subunit | F: NiFeSe_Hases_3rd_1 | ECOD (1.6) |