Open Access
Relay and blockage of protons in water chains
Régis Pomès1,Ching-Hsing Yu1
Structural Biology Biochemistry Programme, Hospital for Sick Children, and Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada.
DOI: 10.2741/1176 Volume 8 Issue 4, pp.1288-1297
Published: 01 September 2003
(This article belongs to the Special Issue Proton transport in biological systems)

The movement of H+ is one of the most important and ubiquitous reactions to take place in biological systems. The gramicidin A (gA) dimer, which forms a water-filled channel selective to small monovalent cations in biological membranes, is used as a model system to study the molecular determinants of biological proton transport with computer simulations. The single-file chain of water molecules, or water wire, embedded in the channel interior mediates the translocation of H+ via a hop-and-turn Grotthuss relay mechanism. Earlier work showing how the mobility of the excess proton in gA is essentially determined by the fine structure and the dynamic fluctuations (structural diffusion) of the hydrogen-bonded network is summarized. The structure and fluctuations of a methanol-containing water chain in the channel lumen suggest a molecular mechanism for the experimentally-measured attenuation of proton conductance by methanol.

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Régis Pomès, Ching-Hsing Yu. Relay and blockage of protons in water chains. Frontiers in Bioscience-Landmark. 2003. 8(4); 1288-1297.