Thread: ATP Synthase

Here's video on the operation of ATP synthase (ATPase) on the inner mitochondrial membrane. I think this is amazing.

The part at the end involving the fluorescent actin filament is very, very clever technology.

http://helios.bto.ed.ac.uk/bto/pml/T...1fo_movie.html

wiked :-D

Interesting animation. It does an excellent job of demonstrating that proteins act by mechanical means. The F0F1 complex works like a mechanical stamping machine in a machine shop. The ADP and P_i are squeezed together so forcefully that they bond. That's where the energy comes from. Mechanical energy stored in chemical energy. It takes just as much energy to break the phosphoanhydride bond as it did to create it in the first place.

Here's another animation that demonstrates other aspects of the process:
ATP Synthase.


As an aside, the F0F1 complex isn't the sole means of ATP production in the cell. Just the most vigorous.


Also, mention is made of that the complex can operate backwards as a proton pump if there is an excess of ATP. I don't think that this would happen in the ordinary operations of things.

The proton-motive force is created by the respiration chain which pumps protons out, and by a serious of antiporters exchanging electrons in:





There are feedback mechanisms which control the amount of ATP created, but turning the F0F1 pump around isn't one of them.
I suppose mention is made of it because in the experiments which led to the current model of the complex, the F1 module is shown to be a ATPase when separated from F0. That is, it burns ATP to spin the gamma subunit.
It was like this that the actin filament was shown.



Anyway.
Fascinating stuff, cellular biology.

Also, mention is made of that the complex can operate backwards as a proton pump if there is an excess of ATP. I don't think that this would happen in the ordinary operations of things.

Yeah. That comment was the only problem I had with the video too.

Originally Posted by invert_nexus

Also, mention is made of that the complex can operate backwards as a proton pump if there is an excess of ATP. I don't think that this would happen in the ordinary operations of things.

It depends on the organism. In chloroplasts it is definitely so, and there are several regulatory mechanisms to block the enzyme as soon as protonmotive force becomes low.
In anaerobic bacteria, however, pumping protons at the expense of ATP hydrolysis is the primary function of ATP synthase (or F-type H⁺-ATPase in this case).
In mitochondria ATP synthesis is a primary function, but ATP-driven proton pumping might also be important.

There is more information on that in the FAQ section at http://www.atpsynthase.info