Oxygen Stability in the New [FeFe]-Hydrogenase from Clostridium beijerinckii SM10 (CbA5H)

The newly isolated [FeFe]-hydrogenase CbA5H was characterized by FTIR spectroscopy coupled to enzy-matic activity assays. This showed for the first time that in this enzyme the oxygen-sensitive active state Hox can be simply and reversibly converted to the oxygen-stable inactive Hinact state. This suggests that oxygen sensitivity is not an intrinsic feature of the catalytic center of [FeFe]-hydrogenases (H-cluster), opening new challeng-ing perspectives on the oxygen sensitivity mechanism as well as new possibilities for the exploitation in industri-al applications.