Question

When the protein gramicidin is integrated into a membrane, an H+ channel forms and the membrane becomes very permeable to protons (H+ ions). If gramicidin is added to an actively respiring muscle cell, how would it affect the rates of electron transport, proton pumping, and ATP synthesis in oxidative phosphorylation? (Assume that gramicidin does not affect the production of NADH and FADH2 during the early stages of cellular respiration.)

Answer 1

Answer with Explanation:

Gramicidine is an antibiotic that has a polypeptide structure and is composed of 3 chains. This molecule can adopt a structure called beta 6-3 helix, so as to form a channel through the cell membrane of bacteria which allows the passage of ions (in this case cations) such as H +, K + or Na +, this situation leads to that in the cell alterations in the content of cellular cations are generated, among the effects the loss of potassium that can cause the death of the cell due to hemolysis due to alteration in the permeability of the membrane is highlighted. This effect is known as the ionophore effect.

An ionophore effect leads to the inhibition in the release of H + to the mitochondrial electronic transport chain.

Gramicidin thanks to its mechanism of action, when it produces interference specifically in a cellular organelle called mitochondria in the inner mitochondrial membrane, it is responsible for interrupting the passage of electrons, alters the gradient of H + and the performance of the enzyme called ATP- synthase which is responsible for producing ATP.

The damage that the entire previous situation produces on oxidative phosphorylation, leads to the refusal of ADP refosphorylation, then ADP and its hydrolysis products will accumulate, and finally the result will be a decrease in ATP levels.