The Structural Plasticity of the Proximal [4Fe3S] Cluster is Responsible for the O2 Tolerance of Membrane-Bound [NiFe] Hydrogenases

The Structural Plasticity of the Proximal [4Fe3S] Cluster is Responsible for the O2 Tolerance of Membrane-Bound [NiFe] Hydrogenases:

The main difference between O₂-sensitive and O₂-tolerant [NiFe] hydrogenases is the plasticity of the proximal [4Fe3S] cluster in the latter hydrogenase (see scheme). Deprotonation of a conserved glutamate residue initiates the movement of the iron atom, resulting in its binding to the amide nitrogen atom of one of the two supernumerary cysteine ligands and superoxidation of the proximal cluster.