Hello !! I am wondering about the electrochemical gradient and the proton pumps in mitochondria - Complexes I, III and IV, how is it created? Protons move from the matrix to the intermembrane space but how is this coupled with electron movement along the chain? Is it because the outer side of the membrane gets negatively charged and that's the driving force for proton movement or is it a confomational change in these complexes that displaces the protons...

Many thanks !!!

I thought it had something to do with NADH and the synthesization of ATP during the electron transport system... Or am I thinking of something else

Yeah, sure. NADH is consumed by Complex I but that's not what I am asking

The different complexes accept the e- from the reduction of NADH and FADH2 which changes the structure of the double bonds in the complexes, the proteins channel the electrons across the membrane but there are other electron carriers such as Coenzyme Q which is a Ubiquinone and this changes it structure from having conjugating double bonds to an aromatic conjugated bond, these electrons are then passed on and this causes electrons to pass across the membrane.

Psycho, thanks !!! I think that I got the idea.