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. 1991 Jul;60(1):101–109. doi: 10.1016/S0006-3495(91)82034-3

Proton conductance by the gramicidin water wire. Model for proton conductance in the F1F0 ATPases?

M Akeson 1, D W Deamer 1
PMCID: PMC1260042  PMID: 1715764

Abstract

The gramicidin channel contains a single strand of water molecules associated through hydrogen bonds. Previous work has shown that channels of similar size are formed by association of transmembrane alpha helices of synthetic leucine-serine peptides. Both types of channels translocate protons with considerable selectivity relative to other cations, and it has been proposed that the selectivity arises by proton "hopping" along hydrogen-bonded chains of water, whereas other cations must cross by ordinary diffusion processes. It is possible that a similar mechanism underlies proton transport in the Fo subunit of the F1F0 ATP synthase. Using the gramicidin channel as a model, we have tested whether a single strand of water is kinetically competent to translocate protons at a rate sufficient to support known rates of ATP synthesis. We found that the gramicidin channel saturates at approximately 530 pS of protonic current in 4 M HCl, more than sufficient for typical ATP synthesis rates. It follows that proton diffusion to a putative channel in Fo, rather than the channel itself, may limit ATP synthesis rates.

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Selected References

These references are in PubMed. This may not be the complete list of references from this article.

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