Infrared Characterization of the Bidirectional Oxygen-Sensitive [NiFe]-Hydrogenase from E. coli
1
Department of Physics, Experimental Molecular Biophysics, Freie Universität Berlin, 14195 Berlin, Germany
2
Department of Physics, Genetic Biophysics, Freie Universität Berlin, 14195 Berlin, Germany
*
Author to whom correspondence should be addressed.
†
These authors contributed equally.
Catalysts 2018, 8(11), 530; https://doi.org/10.3390/catal8110530
Received: 16 October 2018 / Revised: 31 October 2018 / Accepted: 6 November 2018 / Published: 8 November 2018
(This article belongs to the Special Issue Recent Advances in Biocatalysis and Metabolic Engineering for Biomanufacturing)
[NiFe]-hydrogenases are gas-processing metalloenzymes that catalyze the conversion of dihydrogen (H2) to protons and electrons in a broad range of microorganisms. Within the framework of green chemistry, the molecular proceedings of biological hydrogen turnover inspired the design of novel catalytic compounds for H2 generation. The bidirectional “O2-sensitive” [NiFe]-hydrogenase from Escherichia coli HYD-2 has recently been crystallized; however, a systematic infrared characterization in the presence of natural reactants is not available yet. In this study, we analyze HYD-2 from E. coli by in situ attenuated total reflection Fourier-transform infrared spectroscopy (ATR FTIR) under quantitative gas control. We provide an experimental assignment of all catalytically relevant redox intermediates alongside the O2- and CO-inhibited cofactor species. Furthermore, the reactivity and mutual competition between H2, O2, and CO was probed in real time, which lays the foundation for a comparison with other enzymes, e.g., “O2-tolerant” [NiFe]-hydrogenases. Surprisingly, only Ni-B was observed in the presence of O2 with no indications for the “unready” Ni-A state. The presented work proves the capabilities of in situ ATR FTIR spectroscopy as an efficient and powerful technique for the analysis of biological macromolecules and enzymatic small molecule catalysis.
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Keywords:
redox enzymes; FTIR spectroscopy; small molecules
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MDPI and ACS Style
Senger, M.; Laun, K.; Soboh, B.; Stripp, S.T. Infrared Characterization of the Bidirectional Oxygen-Sensitive [NiFe]-Hydrogenase from E. coli. Catalysts 2018, 8, 530.
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