Cited by 134Biochemical Acid Research StudiesEnzyme Structure and FunctionRedox biology and oxidative stress

Inactivation of the 2‐oxo acid dehydrogenase complexes upon generation of intrinsic radical species

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Bunik, Victoria I., Sievers, Christian·2002·European Journal of Biochemistry

Abstract

Self‐regulation of the 2‐oxo acid dehydrogenase complexes during catalysis was studied. Radical species as side products of catalysis were detected by spin trapping, lucigenin fluorescence and ferricytochrome c reduction. Studies of the complexes after converting the bound lipoate or FAD cofactors to nonfunctional derivatives indicated that radicals are generated via FAD. In the presence of oxygen, the 2‐oxo acid, CoA‐dependent production of the superoxide anion radical was detected. In the absence of oxygen, a protein‐bound radical concluded to be the thiyl radical of the complex‐bound dihydrolipoate was trapped by α‐phenyl‐ N ‐ tert ‐butylnitrone. Another, carbon‐centered, radical was trapped in anaerobic reaction of the complex with 2‐oxoglutarate and CoA by 5,5′‐dimethyl‐1‐pyrroline‐ N ‐oxide (DMPO). Generation of radical species was accompanied by the enzyme inactivation. A superoxide scavenger, superoxide dismutase, did not protect the enzyme. However, a thiyl radical scavenger, thioredoxin, prevented the inactivation. It was concluded that the thiyl radical of the complex‐bound dihydrolipoate induces the inactivation by 1e – oxidation of the 2‐oxo acid dehydrogenase catalytic intermediate. A product of this oxidation, the DMPO‐trapped radical fragment of the 2‐oxo acid substrate, inactivates the first component of the complex. The inactivation prevents transformation of the 2‐oxo acids in the absence of terminal substrate, NAD + . The self‐regulation is modulated by thioredoxin which alleviates the adverse effect of the dihydrolipoate intermediate, thus stimulating production of reactive oxygen species by the complexes. The data point to a dual pro‐oxidant action of the complex‐bound dihydrolipoate, propagated through the first and third component enzymes and controlled by thioredoxin and the (NAD + + NADH) pool.

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Crossref · 10.1046/j.1432-1033.2002.03204.x

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  • Mitochondrial enzymes beyond the ETC-pyruvate dehydrogenase, α-ketoglutarate dehydrogenase, and monoamine oxygenase A and B-have been reported to generate ROS.

    “Pyruvate dehydrogenase (887), α-ketoglutarate dehydrogenase (130, 887, 952), and monoamine oxygenase A and B (290) have all been demonstrated to serve as ROS sources.”

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  1. [42]42. Guest, J.R., A li, S.T., A rtymiuk, P., Ford, G.C., Green, J. & Russel, G.C. (1990) Site-directed mutagenesis of dihydrolipoamide acetyltransferase and post-translational modification of its lipoyl domains. In Biochemistry and Physiology of Thiamin Diphosphate Enzymes (Bisswanger, H. & Ullrich, J., eds), pp. 176-193. Chemie, Weinheim.

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Authors
Bunik, V. I., & Sievers, C.
Affiliations
  • Lomonosov Moscow State University (RU)
  • University of Tübingen (DE)
Venue
European Journal of Biochemistry
Publisher
Wiley
Published
2002-09-27
Volume
269
Issue
20
Pages
5004-5015
ISSN
  • 0014-2956 (ISSN-L)
  • 1432-1033
OpenAlex
W1488079166
Cited by
134
References
93
Citations by year
2026: 2 · 2025: 4 · 2024: 3 · 2023: 2 · 2022: 7 · 2021: 9 · 2020: 3 · 2019: 2 · 2018: 6 · 2017: 2 · 2016: 7 · 2015: 7 · 2014: 8 · 2013: 10 · 2012: 6
FWCI
2.39
Type
journal article
Language
en
Open access
Locations
  • European Journal of Biochemistry (publishedVersion)
  • PubMed (publishedVersion)
Topics
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Biochemistry › Biochemical Acid Research Studies
  • Physical Sciences › Materials Science › Materials Chemistry › Enzyme Structure and Function
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Biology › Redox biology and oxidative stress
Keywords
enzyme inactivation, thiyl radicals, FAD, superoxide, thioredoxin, reactive oxygen species, spin trapping, DMPO, alpha-ketoglutarate, NAD+, pro-oxidant activity
MeSH terms
Catalysis, Coenzyme A, Cyclic N-Oxides, Electron Spin Resonance Spectroscopy, Enzyme Activation, Flavin-Adenine Dinucleotide, Free Radicals, Ketone Oxidoreductases, Thioctic Acid, Multienzyme Complexes, NAD, Nitrogen Oxides, Spin Labels, Superoxides, Thioredoxins, 3-Methyl-2-Oxobutanoate Dehydrogenase (Lipoamide)

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