Biochemistry If the difference in pH between the mitochondri

If the difference in pH between the mitochondrial matrix and inter-membrane space is approximately 0.75 pH units, how much energy is stored in the gradient per mole of H\' transferred (pumped)? Assume a temperature of 37°C and a trans (inner) membrane potential of 0.20 V

Solution

Proton Motive Force = (Membrane Electrical Potential) - 2.303 * (RT/F) * delta pH

pmf = 200 mV - 59 (delta pH) = 200 mV - 59 (0.75) mV = 155.75 mV

delta G (Kcal/mol) = zF (delta E) = zF (pmf)

zF = 23.06

delta G (Kcal/mol) = 23.06 * (0.15575 V) = 3.59 Kcal/mol

Since we are talking about energy storage, we take the absolute value, so we neglect the sign convention.

Therefore, the total energy stored in the gradient is 3.59 Kcal per mole.