Comparison of the membrane-bound [NiFe] hydrogenases from R. eutropha H16 and D. vulgaris Miyazaki F in the oxidized ready state by pulsed EPR.
The geometric and electronic structures of the active sites in the oxidized Ni(r)-B state of the [NiFe] hydrogenases from Ralstonia eutropha H16 and Desulfovibrio vulgaris Miyazaki F were investigated in pulsed EPR and ENDOR experiments at two different microwave frequencies (X- and Q-band). Two hyperfine-couplings were clearly resolved in the frozen solution spectra arising from the beta-protons of the nickel-coordinating cysteine residues Cys549 and Cys586 from the Desulfovibrio vulgaris and Ralstonia eutropha hydrogenase, respectively. ESEEM spectroscopic experiments reveal the presence of a histidine in the second coordination sphere of the Ni. The spectroscopic data indicate that the electronic structures of the [NiFe] centers in both hydrogenases are identical in the Ni(r)-B state. However, additional spin couplings of the active site to further paramagnetic centers were identified for the Ralstonia eutropha hydrogenase. The respective couplings could be clearly resolved and simulated. The results from this study are discussed in view of the exceptional O(2)-tolerance of the Ralstonia hydrogenase.
Saggu
Miguel
M
Technische Universität Berlin, Strabetae des 17. Juni 135, 10623 Berlin.
Teutloff
Christian
C
Ludwig
Marcus
M
Brecht
Marc
M
Pandelia
Maria-Eirini
ME
Lenz
Oliver
O
Friedrich
Bärbel
B
Lubitz
Wolfgang
W
Hildebrandt
Peter
P
Lendzian
Friedhelm
F
Bittl
Robert
R
D020134:Catalytic Domain; D020118:Cupriavidus necator / Q000201:enzymology*; D016969:Desulfovibrio vulgaris / Q000201:enzymology*; D004578:Electron Spin Resonance Spectroscopy; D006860:Hydrogen Bonding; D006864:Hydrogenase / Q000737:chemistry*; D010084:Oxidation-Reduction; D013113:Spin Labels
D013113:Spin Labels; C043296:nickel-iron hydrogenase; D006864:Hydrogenase