Additive effect of convergent electron flow

Electron flow converges at the Q-junction from respiratory Complexes I and II (CI+II e-input), glycerophosphate dehydrogenase and electron-transferring flavoprotein. Convergent electron flow corresponds to the operation of the TCA cycle and mitochondrial substrate supply in vivo.

Additive effect

Convergent electron flow simultaneously through CI+II into the Q-junction supports higher OXPHOS and ETS capacities than separate electron flow through either CI or CII. Physiological substrate combinations supporting convergent CI+II e-input are required for reconstitution of intracellular TCA cycle function. The convergent CI+II effect may be completely or partially additive, suggesting that conventional bioenergetic protocols with mt-preparations have underestimated cellular OXPHOS capacities.

References

• Gnaiger E (2009) Mitochondrial pathways through Complexes I+II: Convergent electron transport at the Q-junction and additive effect of substrate combinations. Mitochondr. Physiol. Network 12.12: 1-20.
• Gnaiger E (2009) Capacity of oxidative phosphorylation in human skeletal muscle. New perspectives of mitochondrial physiology. Int. J. Biochem. Cell Biol. 41: 1837–1845.