Does chemiosmosis pump protons or hydronium ions?

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Does chemiosmosis pump protons or hydronium ions?

Post by joneall » Sun Jul 24, 2016 1:30 pm

In the process of chemiosmosis (or the electron transport chain), I always read that the process pumps protons across a membrane -- either the inner membrane of the mitochondria or the thylakoid membrane of chloroplasts. I wonder about this. I suspect that what is really pumped are hydronium ions, H3O+, but I cannot find this on the internet or in any of my books.

Can anyone answer this and maybe provide me with a source URL or book?

Thanks in advance.

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Re: Does chemiosmosis pump protons or hydronium ions?

Post by claudepa » Tue Aug 02, 2016 2:11 pm

Hi. It is indeed written in all books that it is protons. I do not know what is the evidence for proton against hydronium. If there is a channel made by the inner membrane enzymes which translocate the protons into the inter membrane space it could be interesting to know the channel diameter since I suppose hydronium is much bigger than a proton. Samething for the ATP synthase which uses protons from the inter membrane space to make ATP. May be it is known because ATP synthase has been widely studied as a nanomachine. Another question of physic where I had no answer, is the energy of the electrons from the NADH decreasing at each translocating complex until the electron is taken by oxygen or is it constant during the process ? I found both in litterature.

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Re: Does chemiosmosis pump protons or hydronium ions?

Post by leesajohnson » Sat May 20, 2017 10:20 am

The answer will be protons.

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Re: Does chemiosmosis pump protons or hydronium ions?

Post by sharonho1215 » Fri May 26, 2017 3:30 pm

I guess most probably protons as hydronium ions are so big I guess it won't be able to do chemiosmosis. Also, I have read a lot of textbooks and they all say it is proton, they never mention about hydronium ions.