Reversible Active Site Sulfoxygenation Can Explain the Oxygen Tolerance of a NAD+‑Reducing [NiFe] Hydrogenase and Its Unusual Infrared Spectroscopic Properties

Oxygen-tolerant [NiFe] hydrogenases are metalloenzymes that represent valuable model systems for sustainable H2 oxidation and production. The soluble NAD+-reducing [NiFe] hydrogenase (SH) from Ralstonia eutropha couples the reversible cleavage of H2 with the reduction of NAD+ and displays a unique O...

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Bibliographic Details
Published in:Journal of the American Chemical Society 2015-02, Vol.137 (7), p.2555-2564
Main Authors: Horch, Marius, Lauterbach, Lars, Mroginski, Maria Andrea, Hildebrandt, Peter, Lenz, Oliver, Zebger, Ingo
Format: Article
Language:English
Subjects:
Catalytic Domain
Hydrogenase - chemistry
Hydrogenase - metabolism
NAD - metabolism
Oxidation-Reduction
Oxygen - metabolism
Solubility
Spectrophotometry, Infrared
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Summary:Oxygen-tolerant [NiFe] hydrogenases are metalloenzymes that represent valuable model systems for sustainable H2 oxidation and production. The soluble NAD+-reducing [NiFe] hydrogenase (SH) from Ralstonia eutropha couples the reversible cleavage of H2 with the reduction of NAD+ and displays a unique O2 tolerance. Here we performed IR spectroscopic investigations on purified SH in various redox states in combination with density functional theory to provide structural insights into the catalytic [NiFe] center. These studies revealed a standard-like coordination of the active site with diatomic CO and cyanide ligands. The long-lasting discrepancy between spectroscopic data obtained in vitro and in vivo could be solved on the basis of reversible cysteine oxygenation in the fully oxidized state of the [NiFe] site. The data are consistent with a model in which the SH detoxifies O2 catalytically by means of an NADH-dependent (per)­oxidase reaction involving the intermediary formation of stable cysteine sulfenates. The occurrence of two catalytic activities, hydrogen conversion and oxygen reduction, at the same cofactor may inspire the design of novel biomimetic catalysts performing H2-conversion even in the presence of O2.
ISSN:0002-7863
1520-5126
DOI:10.1021/ja511154y