Question

Explain in detail and with drawings, the actual mechanism of ATP synthase (the protein responsible for making ATP) and the use of proton pumps during oxidative phosphorylation and how that leads to the synthesis of ATP. ****See picture below

Answer 1

ATP synthase is an enzyme that creates the energy storage molecule adenosine triphosphate (ATP)

Paul Boyer proposed the binding-change mechanism for catalysis by F-ATPases. He proposed that the binding-change mechanism for ATP synthesis contains three important components:

1. The major energy-requiring step is not the synthesis of ATP from ADP and Pi, but the release of ATP from the enzyme.
2. Substrate is bound and products are released at three separate but interacting catalytic sites, corresponding to the three catalytic subunits (β subunits). Each catalytic site can exist in one of three conformations: tight, loose, or open.
3. The binding changes are coupled to proton transport by rotation of the γ subunit. That is, the flow of protons down their electrochemical gradient through the Fo complex causes the γ subunit to rotate.

Rotation of the γ subunit then brings about the conformational changes in the catalytic complex that allow the release of ATP from the enzyme, and the reaction is driven forward. The reverse occurs when the enzyme functions as an ATP-driven proton pump.

The process, in which energy from a proton gradient is used to make ATP, is called chemiosmosis. More broadly, chemiosmosis can refer to any process in which energy stored in a proton gradient is used to do work. The electron transport chain forms a proton gradient across the inner mitochondrial membrane, which drives the synthesis of ATP via chemiosmosis.

ATP synthase is a lot like a turbine in a hydroelectric power plant. Instead of being turned by water, it’s turned by the flow of H^+​+​​start superscript, plus, end superscript ions moving down their electrochemical gradient. As ATP synthase turns, it catalyzes the addition of a phosphate to ADP, capturing energy from the proton gradient as ATP.

In a eukaryotic cell, the process of cellular respiration can metabolize one molecule of glucose into 30 to 32 ATP. The process of glycolysis only produces two ATP, while all the rest are produced during the electron transport chain. Clearly, the electron transport chain is vastly more efficient, but it can only be carried out in the presence of oxygen.