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Simultaneous Measurement of Superoxide/Hydrogen Peroxide and NADH Production by Flavin-containing Mitochondrial Dehydrogenases
Published on: February 24, 2018
Oxidation of archaeal peroxiredoxin involves a hypervalent sulfur intermediate.
Tsutomu Nakamura1, Takahiko Yamamoto, Manabu Abe
1National Institute of Advanced Industrial Science and Technology, Ikeda, Osaka 563-8577, Japan. nakamura-t@aist.go.jp
Summary
Protein thiol oxidation, crucial for disulfide bonds and reactive oxygen species, proceeds via a hypervalent sulfur intermediate. This study reveals a novel sulfurane structure in archaeal peroxiredoxin, detailing a new thiol oxidation mechanism.
Area of Science:
- Biochemistry
- Structural Biology
- Enzyme Mechanisms
Background:
- Protein thiol oxidation is vital for disulfide bond formation and managing reactive oxygen species.
- Cysteine sulfenic acid (Cys-SOH) is the accepted initial oxidation product of cysteine residues.
Purpose of the Study:
- To elucidate the mechanism of thiol oxidation through a hypervalent sulfur intermediate.
- To present crystallographic and computational evidence for this novel mechanism.
Main Methods:
- X-ray crystallography of archaeal peroxiredoxin (ApTPx) at 1.77 A resolution.
- Quantum chemical calculations.
- Analysis of hydrogen bond networks and flexible loop dynamics.
Main Results:
- Crystallographic data revealed a cysteine sulfenic acid derivative in ApTPx.
- This derivative was identified as a sulfurane, a hypervalent sulfur compound, with S(gamma) covalently linked to His-42.
- Quantum chemical calculations supported the formation and stability of this hypervalent intermediate.
Conclusions:
- A novel thiol oxidation mechanism involving a hypervalent sulfur intermediate (sulfurane) has been demonstrated.
- This finding challenges the traditional view of cysteine oxidation initiation.
- Hypervalent sulfur compounds play a significant role in biochemical redox processes.
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