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Active Site of the NAD+-Reducing Hydrogenase from Ralstonia eutropha Studied by EPR Spectroscopy B
- Löwenstein, Julia, Lauterbach, Lars, Teutloff, Christian, Lenz, Oliver, Bittl, Robert
- The Journal of physical chemistry 2015 v.119 no.43 pp. 13834-13841
- Cupriavidus necator, active sites, electron paramagnetic resonance spectroscopy, histidine, hydrides, iron, lighting, nickel, oxygen, variance
- Pulsed ENDOR and HYSCORE measurements were carried out to characterize the active site of the oxygen-tolerant NAD⁺-reducing hydrogenase of Ralstonia eutropha. The catalytically active Niₐ-C state exhibits a bridging hydride between iron and nickel in the active site, which is photodissociated upon illumination. Its hyperfine coupling is comparable to that of standard hydrogenases. In addition, a histidine residue could be identified, which shows hyperfine and nuclear quadrupole parameters in significant variance from comparable histidine residues that are conserved in standard [NiFe] hydrogenases, and might be related to the O₂ tolerance of the enzyme.