Question

The ∆Go’ for oxidation of FADH2 by O2 when the FADH2 is free in solutoin is -199.5 kJ/mol. The is ∆Go’ for oxidation of FADH2 by O2 when the FADH2 is in a flavoprotein is

Answer 1

$\Delta$G^O' is a free energy change under standard condition

  $\Delta$G^O' = -nF$\Delta$E^{O '}

FADH₂ +1/2 O₂$\rightleftharpoons$ FAD + H₂O + 2e^- (flavoproteins)

$\Delta$E^{O '} = 0.000 volts So $\Delta$G^O' is also 0 kJ/mol

There will be self exchange of electrons between O₂ and O^- where $\Delta$G^O' will be 0.