Question

Can an uncoupler of oxidative phosphorylation inhibit electron transport from one component of the electron transport chain to another? Why or why not?

Answer 1

Answer: No

Explanation:

An uncoupler is an inhibitor of oxidative phosphorylation. It does not inhibit any of the components of the electron transport chain. However, it increases the fluidity of the inner mitochondrial membrane for protons. So, protons easily diffuse through the inner mitochondrial membrane thereby dissipating the proton gradient created by NADH and FADH2. Hence it results in the uncoupling of the proton gradient from oxidative phosphorylation.

Since the diffusion of protons into the inter membranal space increases, the pH in the inter membranal space decreases after DNP treatment.

pH = -log[H+]

Uncouplers were used as a therapeutic to reduce weight as energy(ATP) is not produced by the NADH and FADH2. They were discontinued later due to several reasons such as the production of excess heat in the body.

Ex: DNP (Dinitrophenol)