The metabolism of many anaerobes relies on [NiFe]-hydrogenases, whose characterization when bound to substrates has proven non-trivial. Presented here is direct evidence for a hydride bridge in the active site of the 57 Fe-labelled fully reduced Ni-R form of Desulfovibrio vulgaris Miyazaki F [NiFe]-hydrogenase. A unique ' wagging' mode involving H- motion perpendicular to the Ni(μ1/4-H)57 Fe plane was studied using 57 Fe-specific nuclear resonance vibrational spectroscopy and density functional theory (DFT) calculations. On Ni(μ1/4-D) 57 Fe deuteride substitution, this wagging causes a characteristic perturbation of Fe-CO/CN bands. Spectra have been interpreted by comparison with Ni(μ1/4-H/D) 57 Fe enzyme mimics [(dppe)Ni(μ1/4-pdt)(μ1/4-H/D) 57 Fe(CO)3 ]+ and DFT calculations, which collectively indicate a low-spin Ni(II)(μ1/4-H)Fe(II) core for Ni-R, with H- binding Ni more tightly than Fe. The present methodology is also relevant to characterizing Fe-H moieties in other important natural and synthetic catalysts.
ASJC Scopus subject areas
- Biochemistry, Genetics and Molecular Biology(all)
- Physics and Astronomy(all)