Observation of the FeCN and FeCO Vibrations in the Active Site of [NiFe] Hydrogenase by Nuclear Resonance Vibrational Spectroscopy

Abstract

Nuclear inelastic scattering of 57Fe labeled [NiFe] hydrogenase is shown to give information on different states of the enzyme. It was thus possible to detect and assign Fe–CO and Fe–CN bending and stretching vibrations of the active site outside the spectral range of the Fe–S cluster normal modes.

Spectroscopic Investigations of [FeFe] Hydrogenase Maturated with [57Fe2(adt)(CN)2(CO)4]2–

“…The NRVS spectrum of the precursor displays intense bands in the regions assigned to Fe-CO stretching and Fe–C–O bending (six bands between 490 and 650 cm −1 ) and the Fe-CN region (two bands between 400 and 500 cm −1 ). 28,29 Comparing the spectrum of the precursor to that for the HydA1 H ox -CO spectrum, one can clearly see that the Fe–C bands are strongly affected, with Fe- CO modes being (on average) red-shifted and Fe-CN modes being blue-shifted. The Fe-CO/-CN shift is consistent with major changes in the primary coordination sphere of the Fe centers upon insertion into the enzyme and conversion to H ox -CO.…”

Characterization of the [3Fe–4S]0/1+cluster from the D14C variant of Pyrococcus furiosus ferredoxin via combined NRVS and DFT analyses

“…16 57 Fe partial vibrational density of states ( 57 Fe-PVDOS) for oxidized and reduced samples from the new NRVS measurements are presented in Fig. 2, A and B, respectively.…”

NRVS for Fe in Biology: Experiment and Basic Interpretation

“…Besides non-Rieske [2Fe2S] 22 and [3Fe4S] 23 proteins and [4Fe4S] 24 proteins, It is important to note that 57 Fe NRVS has been expanded to study electron transfer in larger enzymes and their catalytic metallocofactors such as (but not comprehensively) the NiFe site in [NiFe] hydrogenase, 3, 25–26 the diiron site in [FeFe] hydrogenase, 27–28 the P [8Fe7S]- and M [7Fe9SMo]- clusters of Mo-Nitrogenase, 29–32 heme systems, 33–34 non-heme systems, 35–36 and nitric-oxide sensing [4Fe4S] clusters. 37 Further as the systems of interest have become more complicated, with multiple FeS clusters of differing composition, innovative strategies of site-specific 57 Fe labeling have been implemented that target maturation 28 or a modified cofactor insertion.…”