@article {661,
	title = {Protons May Leak through Pure Lipid Bilayers via a Concerted Mechanism},
	journal = {Biophys J},
	volume = {88},
	number = {5},
	year = {2005},
	note = {Tepper, Harald L Voth, Gregory A 1 S10 RR17214-01/RR/NCRR NIH HHS/United States R01 GM053148/GM/NIGMS NIH HHS/United States Research Support, N.I.H., Extramural Research Support, Non-U.S. Gov{\textquoteright}t Research Support, U.S. Gov{\textquoteright}t, P.H.S. United States Biophysical journal Biophys J. 2005 May;88(5):3095-108. Epub 2005 Feb 4.},
	pages = {3095-108},
	abstract = {<p>Protons are known to permeate pure lipid bilayers at a rate that is anomalous compared to those of other small monovalent cations. The prevailing mechanism via which they cross the membrane is still unclear, and it is unknown how to probe the mechanism directly by experiment. One of the more popular theories assumes the formation of membrane-spanning single-file water wires providing a matrix along which the protons can "hop" over the barrier. However, free energy calculations on such structures (without the presence of an excess proton) suggest that this mechanism alone cannot account for the observed permeation rates. We use the multistate empirical valence bond method to directly study water structures surrounding a (delocalized) excess proton on its way through the membrane. We find that membrane-spanning networks, rather than single-file chains, are formed around the proton. We also find that such structures are considerably stabilized in the presence of the proton, with lifetimes of several hundreds of picoseconds. The observed structures are suggestive of a new, concerted, mechanism and provide some direction for further investigation.</p>},
	keywords = {Biophysics/*methods Hydrogen Bonding Ion Channels Lipid Bilayers/*chemistry Membrane Lipids/chemistry Models, Molecular Models, Statistical Oxygen/chemistry Phospholipids/chemistry *Protons Thermodynamics Time Factors Water/chemistry},
	doi = {10.1529/biophysj.104.056184},
	author = {H. L. Tepper and G. A. Voth}
}
