NADH‐Induced Changes of the Nickel Coordination within the Active Site of the Soluble Hydrogenase from <i>Alcaligenes eutrophus</i>: XAFS Investigations on Three States Distinguishable by EPR Spectroscopy

Abstract

A heterobinuclear Ni-Fe-S center similar to that in the hydrogenase from Desulfovibrio gigas is also present in the considerably more complex soluble hydrogenase from the bacterium Alcaligenes eutrophus, as shown by high-resolution X-ray absorption spectroscopy. Reductive activation of this enzyme with NADH leads to a substantial change in the coordination of the nickel, which is probably due to specific substrate properties. A model for the active site after NADH reduction is shown on the right.