NRVS Spectroscopy Resolves Distinct Bridging Hydride Intermediates in [NiFe]-Hydrogenase

TL;DR

Scientists used a special technique to study hydrogenase enzymes and found distinct hydride intermediates that help in hydrogen sensing.

Contribution

The study reveals distinct bridging hydride intermediates in [NiFe]-hydrogenase using NRVS, offering new insights into its catalytic mechanism.

Findings

NRVS detected metal–hydride vibrations in Nia-C and Nia-SR intermediates.

Fe–hydride bands show a large energy gap, indicating different bonding interactions.

Structural rigidity of the [NiFe] center is conserved and important for electron transfer.

Abstract

The active-site iron of an H2-sensing [NiFe]-hydrogenase
was selectively labeled with 57Fe, allowing the probing
of all catalytic intermediates using synchrotron-based nuclear resonance
vibrational spectroscopy. Diagnostic metal–hydride vibrations
were detected for both the Nia-C and Nia-SR
intermediates, with their assignments being confirmed through H/D
isotope substitution and in situ hydride photolysis experiments. Interestingly,
these Fe–hydride bands are separated by a large energy gap,
reflecting distinct bonding interactions at the metal–hydride
site. Despite these differences, vibrational analyses across all catalytically
active species reveal a conserved structural rigidity of the [NiFe]
center, which appears crucial for sustaining efficient and rapid electron
transfer in [NiFe]-hydrogenases.

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