Question

Which of the following sequences represents the three conformations of F1?

A. 1) open: ADP + Pi enter 2) react: ADP + Pi bind 3) release: exit the complex
B. 1) react: ADP + Pi bind 2) release: exit the complex 3) open: ADP + Pi enter
C. 1) release: exit the complex 2) open: ADP + Pi enter 3) react: ADP + Pi bind
D. 1) open: ADP + Pi enter 2) release: exit the complex 3) react: ADP + Pi bind

Answer 1

The appropriate conformation sequence for the ATP-synthase F1 portion is 'Open,' 'Loose-state (react),' 'Tight-state (react),' and then back to 'Open' to release ATP and repeat the process. Option B (React, Release, Open) is the closest match to the process, even though it does not describe all of the specific states.

Step-by-step explanation:

The conformations of F1 portion of ATP-synthase involve a series of changes linked with the mechanism of ATP synthesis. Specifically, the sequence representing these conformations, according to the information provided, is:

1. Open: ADP + Pi enter.
2. Loose-state (react): ADP + Pi bind loosely.
3. Tight-state (react): The F1ß tightens around ADP and P, converting them into ATP.
4. Revert to open-state (release): ATP is released and ADP and P can enter to repeat the process.

From the given options, none of them perfectly matches the process as described in the information given. However, Option B is the closest to it, and with some interpretation could represent the sequence as it encompasses the key stages in the correct order with an 'open' state allowing ADP and Pi to enter, followed by a 'react' state where they bind, and finally a 'release' state where products exit the complex. Here's the representation:

1. React: ADP + Pi bind.
2. Release: Exit the complex.
3. Open: ADP + Pi enter.