Abstract
A hydrogenase(Hase) is an enzyme that catalyzes the reversible redox reaction between hydrogen ion and hydrogen. Hase is easily inactivated under an oxygen atmosphere. The[Ni-Fe-Se]-Hase is more stabilized against oxygen molecules than the[Ni-Fe]-Hase. The former, however, has a selenocysteine nearby the active site; therefore the large-scale production is difficult by protein engineering. The calculations of the electron structures of[Ni-Fe]- and[Ni-Fe-Se]-Hases have been carried out, in order to clarify mechanism of the inactivation reaction. Consequently, not only selenocystein but also the nearest-neighbor amino acid residues on the active site have contributed to the stabilization. In other words, the[Ni-Fe]-Hase, which has no selenocystein, has possibilities to stabilize against oxygen molecule by amino acids substitution. This study will provide a new design for industrial application of Hase.
