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Protein Film Infrared Electrochemistry Demonstrated for Study of H2 Oxidation by a [NiFe] Hydrogenase
Published on: December 4, 2017
Isocyanides inhibit [Fe]-hydrogenase with very high affinity.
1Max-Planck-Institut für terrestrische Mikrobiologie, Marburg, Germany. shima@mpi-marburg.mpg.de
FEBS Letters
|December 21, 2010
Summary
Isocyanides strongly inhibit [Fe]-hydrogenase, a key enzyme in hydrogen metabolism, by binding to its active iron site. This discovery offers new insights into enzyme inhibition mechanisms.
Area of Science:
- Biochemistry
- Enzyme kinetics
- Bioinorganic chemistry
Background:
- [Fe]-hydrogenase catalyzes reversible H(2) activation.
- Carbon monoxide (CO) and cyanide (CN-) are known inhibitors of [Fe]-hydrogenase, binding to the iron site of the cofactor with low affinity.
Purpose of the Study:
- To investigate the inhibitory effects of isocyanides on [Fe]-hydrogenase.
- To compare the inhibitory potential of isocyanides with CO and CN-.
- To elucidate the binding site and mechanism of isocyanide inhibition.
Main Methods:
- Enzyme inhibition assays using varying concentrations of isocyanides.
- Spectroscopic analysis (UV-Vis and infrared) to determine cofactor binding.
- Kinetic studies to analyze inhibition patterns.
Main Results:
- Isocyanides strongly inhibit [Fe]-hydrogenase with inhibition constants (K(i)) as low as 1 nM.
- Isocyanides did not inhibit [NiFe]- and [FeFe]-hydrogenases.
- Spectroscopic data confirmed isocyanide binding to the iron center of [Fe]-hydrogenase.
- Inhibition kinetics align with the proposed catalytic mechanism, including enzyme conformational changes.
Conclusions:
- Isocyanides are potent inhibitors of [Fe]-hydrogenase, distinct from CO and CN-.
- The specific inhibition of [Fe]-hydrogenase by isocyanides highlights unique enzyme properties.
- Understanding isocyanide binding provides mechanistic insights into [Fe]-hydrogenase function and regulation.
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