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Metabolic control analysis of mitochondrial aconitase: influence over respiration and mitochondrial superoxide and

F Scandroglio1, V Tórtora, R Radi

  • 1Departamento de Bioquímica and Center for Free Radical and Biomedical Research, Facultad de Medicina, Universidad de la República , Montevideo , Uruguay.

Free Radical Research
|March 8, 2014
PubMed

Insights

Oxidant-induced inactivation of mitochondrial aconitase impacts cellular respiration and reactive oxygen species production. This enzyme plays a key role in regulating mitochondrial function and preventing oxidative damage.

Area of Science:

  • Mitochondrial biochemistry
  • Cellular metabolism
  • Enzyme kinetics

Background:

  • Mitochondrial aconitase, containing an iron-sulfur (Fe-S) cluster, is sensitive to oxidants.
  • Oxidant-induced inactivation is reversible with reductants and iron.
  • The metabolic consequences of aconitase inhibition are not fully understood.

Purpose of the Study:

  • To investigate the metabolic impact of oxidant-dependent aconitase inhibition.
  • To analyze effects on the citric acid cycle, respiratory chain, and reactive species formation.
  • To determine tissue-specific roles of aconitase in metabolic control.

Main Methods:

  • Metabolic analysis using isolated mitochondria from various rat tissues.
  • Enzyme inhibition studies using fluorocitrate titrations.
  • Measurement of mitochondrial oxygen consumption, membrane potential, and hydrogen peroxide production.

Main Results:

  • Aconitase inhibition showed IC50 values between 7-24 μM and affected oxygen consumption from 63-98%.
  • Brain and heart mitochondria exhibited high flux control coefficients (> 0.95) for aconitase.
  • Aconitase activity decreased at 21% O2 and increased at 2% O2 in brain and heart, indicating oxidant inactivation. Mitochondrial membrane potential and H2O2 production decreased upon aconitase inhibition in heart and brain.

Conclusions:

  • Aconitase exerts tissue-specific control over mitochondrial respiration.
  • Aconitase inactivation may serve as a protective mechanism against reactive oxygen species formation by the respiratory chain.
  • These findings highlight aconitase's role in cellular redox homeostasis.

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