[NiFe]ヒドロゲナーゼ研究における共鳴ラマン分光法の適用範囲拡大：新たな観測可能状態とレポーター振動
Oxygen-tolerant [NiFe] hydrogenases serve as model systems for molecular hydrogen activation and production. Resonance Raman spectroscopy has been used to probe metal-ligand coordinates at the [NiFe] active site and FeS clusters, but its utility has been constrained by a limited number of detectable states and assignment difficulties. By extending the excitation and detection wavelength ranges in two oxygen-tolerant [NiFe] hydrogenases, this study demonstrates that resonance Raman spectroscopy can access not only low-frequency metal-ligand vibrations but also high-frequency intra-ligand modes of the diatomic CO and CN ligands. These modes are typically monitored by infrared absorption spectroscopy, enabling direct cross-comparison for unambiguous state assignment. Additionally, a previously unobserved active-site state bearing a bridging hydroxo ligand between Ni and Fe was detected by using longer excitation wavelengths, thereby circumventing photoconversion artifacts seen at shorter wavelengths. The findings broaden the methodological toolkit for characterizing redox-structural states in hydrogenases and related complex metalloenzymes.
Extending excitation wavelengths avoids photoconversion artifacts, enabling resonance Raman detection of a bridging hydroxo ligand state between Ni and Fe at the [NiFe] hydrogenase active site; high-frequency CO/CN intra-ligand modes serve as cross-validation reporters against infrared spectra.
This is basic research at the cellular or molecular level. For human application, inhalation is the most promising delivery route, but inhalation carries explosion risk and concentration matters (empirical LFL of 10%; high-concentration devices are not recommended).
See also:
https://h2-papers.org/en/papers/39326301