Oxidative phosphorylation and electrochemical gradient

[deleted783484]

Complex I results in oxidation of NADH to NAD+ and two electrons flow from the mitochondria matrix to the complex that is embedded in the inner membrane of the mitochondria.

I am trying to find an explanation to why 4H+ are pumped to the intermembrane space. Is it because electrons left the mitochondria matrix resulting in a more positive mitochondria matrix and so protons diffuse from high to low concentration and therefore they move to the intermembrane space?

Thanks a lot!

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[aldol16]

This movement of protons is actually unfavorable. It's the redox reaction between NAD+/NADH and Q/QH2 that drives the proton translocation forward.

http://www.biochemj.org/content/425/2/327

 

[deleted783484]

This movement of protons is actually unfavorable. It's the redox reaction between NAD+/NADH and Q/QH2 that drives the proton translocation forward.

http://www.biochemj.org/content/425/2/327

Could you please clarify? I didn't understand this statement ". In mitochondria, the electron transport chain transfers two electrons from NADH to oxygen; it extracts the potential energy in three sequential steps, and uses it to transport protons across the mitochondrial inner membrane, to produce and sustain the protonmotive force"

I don't really understand what drives the protons from complex I to IV to exit to the intermembrane space but I get that this proton distribution will create a higher voltage difference across the membrane and a lower ph in the intermembrane space and this electrochemical gradient will drive atp synthase but I don't understand why it would pump these protons initially

 

[aldol16]

It pumps the protons because that's what the complexes are designed to do. That's like asking why a basement pump pumps water from the basement to the ground level. It does that because it's designed to do so. The pump binds protons on one side and releases them on the other. The exact mechanism of how this works is still unknown.