Lactose transporter of E. coli is a well-studied proton driven cotransporter. It transports one lactose molecule together with one proton into the cell. Calculate the free energy change for...

Lactose transporter of E. coli is a well-studied proton driven cotransporter. It transports one lactose molecule together with one proton into the cell. Calculate the free energy change for transporting one more of protons into the cell? Membrane potential is -50 mV (inside is negative) and the pH = 7.2 inside the cell and the pH = 4.0 outside the cell. Temperature is 37 degrees celsius (310K). Remeber to convert pH to (H+) and express your answer as kJ/mol.