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

The newly isolated Clostridium beijerinckii [FeFe]-hydrogenase CbA5H was characterized by Fourier transform infrared spectroscopy coupled to enzymatic activity assays. This showed for the first time that in this enzyme the oxygen-sensitive active state H can be simply and reversibly converted to the oxygen-stable inactive H state. This suggests that oxygen sensitivity is not an intrinsic feature of the catalytic center of [FeFe]-hydrogenases (H-cluster), opening new challenging perspectives on the oxygen sensitivity mechanism as well as new possibilities for exploitation in industrial applications.