Question

(30 pts) You are in lab making a purified ATP synthase preparation. You have lysed your cells and gotten the ATP synthase into artificial liposomes with F1 facing the interior of the liposome. You have prepared everything at pH 7 including the liposomes. If you take the preparation and split into 3 different vials of pH 3, 6, and 10, what do you think will happen in each of the vials? Explain.

Answer 1

F0-F1 ATP synthase can synthesize ATP as well as hydrolyze ATP depending upon the H+ gradient.

Fo-F1 ATPsynthase synthesizes ATP by using the energy released by the transfer of H+ from higher concentration to lower concentration.

pH depends on the H+ concentration, lower the pH higher is the H+ concentration.

when the liposome is in the solution containing pH=7. the pH inside the liposome is 7 there is no H+ gradient so ATP is not synthesized or hydrolyzed.

when the liposome is in a solution containing pH 3.

the concentration of H+ is high in the solution so the F0-F1 ATP synthase transports H+ to the liposome and use the released energy to make ATP from ADP and Pi.

when the liposome is in a solution containing pH 6.

the concentration of H+ is high in the solution so the F0-F1 ATP synthase transports H+ to the liposome and use the released energy to make ATP from ADP and Pi.

when the liposome is placed in a solution containing pH 10.

the concentration of H+ is high in the liposome ( liposome has low pH compared to the solution ) so F0-F1 ATP synthase transports H+ from the liposome to the solution, and the ATP is hydrolysed to ADP and Pi during this process.