Non-standard structures of the Ni-Fe cofactor in the regulatory and the NAD-reducing hydrogenases from Ralstonia eutropha

Spectroscopy on two oxygen-insensitive Ni-Fe hydrogenases from Ralstonia eutropha (NAD-reducing, soluble hydrogenase; hydrogen sensor, regulatory hydrogenase) reveals non-standard catalytic behaviour and unique structures of their Ni-Fe cofactors. Possible mechanistic implications are briefly discussed.