ATP is synthesized from ADP, Pi, and a proton on the matrix side of theinner mitochondrial membrane. We will refer to the matrix side as the“inside” of the inner mitochondrial membrane (IMM).(a) H+ transport from the outside of the IMM into the matrix drives this process. The pH inside the matrix is 8.2, and the outside is more acidic by0.8 pH units. Assuming the IMM membrane potential is 168 mV (insidenegative), calculate ΔG for the transport of 1 mol of H+ across the IMMinto the matrix at 37 °C : H+(outside) → H+(inside).(b) Assume three mol H+ must be translocated to synthesize one mol ATPby coupling of the following reactions:ADP + Pi + H+(inside) → ATP + H2O (ATP synthesis)3H+(outside) → 3H+(inside) ( proton transport)Write the overall reaction for ATP synthesis coupled to H+ transport[and use this equation for part (c)]:(c) Assume three mol H+ must be translocated to synthesize one mol ATPas described in part (b) above. Given the following steady-state concentrations: ATP = 2.70 mM and Pi = 5.20 mM, the membrane potentialΔψ = 168 mV (inside negative), and the pH values in part (a), calculate the steady-state concentration of ADP at 37 °C when for the coupledprocess (ATP synthesis + H+ transport), ΔG = -11.7 kJ/mol.
ATP is synthesized from ADP, Pi, and a proton on the matrix side of the
inner mitochondrial membrane. We will refer to the matrix side as the
“inside” of the inner mitochondrial membrane (IMM).
(a) H+ transport from the outside of the IMM into the matrix drives this process. The pH inside the matrix is 8.2, and the outside is more acidic by
0.8 pH units. Assuming the IMM membrane potential is 168 mV (inside
negative), calculate ΔG for the transport of 1 mol of H+ across the IMM
into the matrix at 37 °C : H+(outside) → H+(inside).
(b) Assume three mol H+ must be translocated to synthesize one mol ATP
by coupling of the following reactions:
ADP + Pi + H+(inside) → ATP + H2O (ATP synthesis)
3H+(outside) → 3H+(inside) ( proton transport)
Write the overall reaction for ATP synthesis coupled to H+ transport
[and use this equation for part (c)]:
(c) Assume three mol H+ must be translocated to synthesize one mol ATP
as described in part (b) above. Given the following steady-state concentrations: ATP = 2.70 mM and Pi = 5.20 mM, the membrane potential
Δψ = 168 mV (inside negative), and the pH values in part (a), calculate the steady-state concentration of ADP at 37 °C when for the coupled
process (ATP synthesis + H+ transport), ΔG = -11.7 kJ/mol.
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