Question

Explain why isolated F1 subunits from the ATP synthase enzyme catalyze the hydrolysis of ATP. Use protein structure, conformational changes, and free energy in your response.

Answer 1

The F1 headpiece of the enzyme ATP synthase is a peripheral membrane protein complex and contains ATP synthesis from ADP and inorganic phosphate. The F₀ is an intergral protein complex of the membrane that forms the channel via which the protons cross the inner membrane.

The F1 subunit drives the conformation change which is the rotation of central stalk but it is still not clear if the ATP molecule hydrolysis its own self or its binding to the F1 site induces the rotation. Some researchers believe that the ATP binding and its products unbinding provide main power stroke and the real catalysis occurs inside the binding pockets. The site of catalysis lowers the barrier of reaction in direction of the formation of product that is ATP considerable enough to cause efficient amount of hydrolysis.

The proton passage from the F₀ channel is coupled to the catalytic site in F1 for ATP production. For each ATP 2 H+ pass via the the channel from the intermembrane space to the matrix down electrochemical gradient.

During NADH+H+ oxidation three protons are pushed down and two pairs of protons are required for one FADH₂. The complete oxidation of the NADH give 3 molecules of ATP and of one FADH₂ give 2 molecules of ATP.

ATP SYNTESIS IN MITOCHONDRIA Adenosine (ADP: Toe Inorganic (Pri Phosphate) 2H+ OUTER SPACE MATRIX INTER CHONDRIAL (ADP) (Pi) MEMBRANE