Quantitative considerations of Ox.Phos

Question 1

How do you work out the electrical gradient ΔΨ?

Answer 1

ΔΨ= -RT/zF ln([Ain]/[Aout])
A= ion

Question 2

How do you work out ΔpH?

Answer 2

ΔpH= pH in - pH out

Question 3

How do you find out the proton motive force Δp?

Answer 3

Δp = ΔΨ - 0.06ΔpH

- has to be in V

Question 4

How do you measure the electrical gradient ΔΨ?

Answer 4

1. use phosphonium cations (TMP+)
2. measure the mitochondrial matrix volume
3. measure [TMP+] out directly using electrodes

Question 5

How do you indirectly measure the ΔpH?

Answer 5

- assuming that pKa of acid is same in and out
at equilibrium:
pH = -log10[H+]
not in equilibrium:
ΔpH = log10 [A-]in / [A-] out

Question 6

How do you work out how much energy is released for a proton to move across a membrane?

Answer 6

ΔG = -mFΔp
Δp = electrochemical potential in V
F = faradays constant
m = no. ions pumped

Question 7

How do you work out how much energy is required for a proton to move across a membrane?

Answer 7

ΔG = ΔG0 + RT ln ([C][D]/[A][B])