E

{{MitoPedia |abbr=E |description= ET capacity is the respiratory electron transfer pathway capacity, E, of mitochondria measured as oxygen consumption in the noncoupled state at optimum uncoupler concentration. This optimum concentration is obtained by stepwise titration of an established protonophore to induce maximum oxygen flux as the determinant of ET capacity.

Electron transfer pathway capacity determined in intact cells is typically lower than that inducible in permeabilized cells. The reason is that in the latter substrates are normally provided at (near-)saturating conditions, whereas in intact cells respiration is fuelled by endogenous substrates possibly supplemented with external substrates the uptake of which is limited by the activity of cell membrane transporting pathways.

For a more comprehensive account see ET capacity.