SEIRA Spectroscopy of the Electrochemical Activation of an Immobilized [NiFe] Hydrogenase under Turnover and Non-Turnover Conditions

摘要

[NiFe] hydrogenases are a family of metalloenzymes that catalyze the reversible splitting of molecular hydrogen into protons and electrons. These enzymes contain an electron-transfer chain of FeS clusters linking the external redox partner with the active site, a [NiFe] center. This bimetallic complex includes two terminal cysteine residues bound to the Ni atom, three diatomic inorganic ligands (one CO and two CN~-) bound to the Fe atom, and two cysteine residues bridging the Ni and Fe atoms. The [NiFe] center may exist in various states, differing with respect to the oxidation state of the Ni atom and the nature of the exogenous ligand bridging the Ni and Fe atoms. Most of the information about the active-site structure in these states has been obtained by EPR and IR spectroscopy, leading to a better understanding of the catalytic processes in the hydrogen metabolism of (an) aerobic microorganisms.