Question

For the experimental system described in Problem 17, and assuming all the substrates for oxidative phosphorylation are present in excess, does ATP synthesis increase or decrease with an increase in the pH of the fluid in which the submitochondrial particles are suspended?

Short answer

ATP synthesis increases with an increase in the pH of the fluid in which the submitochondrial particles are suspended.

Step-by-step solution

Electrochemical gradient

A gradient of electrochemical potential, usually for an ion that may penetrate a membrane, is known as an electrochemical gradient.

Experiment in problem 17

From the previous problem, the whole process of electron transfer is reversed in case the particles $({\text{F}}_{\text{o}}{\text{F}}_{\text{1}}\text{ATPase)}$change their orientation. Here${\text{H}}^{+}$ shifts from intermembrane space to the matrix. Then the intermembrane space gets negatively charged, so there is shift of${\text{H}}^{+}$ from matrix to cytosol.

More ATP is synthesized

The flux of${\text{H}}^{+}$ through ATP should be increased if the pH of intermembrane space is increased, due to the electrochemical gradient. Due to difference in the potential, the${\text{H}}^{+}$ transfer gets inhibited until another${\text{H}}^{+}$ is "returned" via ${\text{F}}_o{\text{F}}_1$ATPase.

Hence, it is concluded that greater the number of ${\text{H}}^{+}$is transferred to the cytosol, more ATP synthesized.