Abstract.
In this study we report on thus-far unobserved proton hyperfine couplings in the well-known EPR signals of [NiFe] hydrogenases. The preparation of the enzyme in several highly homogeneous states allowed us to carefully re-examine the Niu*, Nir*, Nia-C* and Nia-L* EPR signals which are present in most [NiFe] hydrogenases. At high resolution (modulation amplitude 0.57 G), clear indications for hyperfine interactions were observed in the g z line of the Nir* EPR signal. The hyperfine pattern became more pronounced in 2H2O. Simulations of the spectra suggested the interaction of the Ni-based unpaired electron with two equivalent, non-exchangeable protons (A 1,2=13.2 MHz) and one exchangeable proton (A 3=6.6 MHz) in the Nir* state. Interaction with an exchangeable proton could not be observed in the Niu* EPR signal. The identity of the three protons is discussed and correlated to available ENDOR data. It is concluded that the NiFe centre in the Nir* state contains a hydroxide ligand bound to the nickel, which is pointing towards the gas channel rather than to iron.
Article PDF
Similar content being viewed by others
Avoid common mistakes on your manuscript.
Author information
Authors and Affiliations
Additional information
Electronic Publication
Rights and permissions
About this article
Cite this article
Bleijlevens, B., Faber, B.W. & Albracht, S.P. The [NiFe] hydrogenase from Allochromatium vinosum studied in EPR-detectable states: H/D exchange experiments that yield new information about the structure of the active site. J. Biol. Inorg. Chem. 6, 763–769 (2001). https://doi.org/10.1007/s007750100252
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s007750100252