Proton-wire

Vendrell O, Gelabert R, Moreno M, Lluch M (2008) Operation of the proton wire in green fluorescent protein. A quantum dynamics simulation. J Phys Chem B 112 5500-5511... 

Leiderman P, Huppert D, Agmon N (2006) Transition in the temperature-dependence of GFP fluorescence From proton wires to proton exit. Biophys J 90 1009-1018... 

Burykin, A. Warshel, A., What really prevents proton transport through aquaporin Charge self-energy versus proton wire proposals, Biophys. J. 2003, 85, 3696-3706... 

Pomes, R. Roux, B., Theoretical study of H+ translocation along a model proton wire, J. Phys. Chem. 1996,100, 2519-2527... 

Linear arrays of protonatable or hydrogen bonded sites may allow the directed long range transfer of protons, thus functioning as proton-conducting channel, i.e., as proton wire. Relevant systems would be linear polyamines or polyphenolic condensed aromatic units [8.218], self-assembled hydrogen bonded heterocyclic ribbons such as 116 (see Section 9.4.4) or polyelectrolyte membranes [8.219] in which collective proton motion may take place and lead to proton conductivity. 

Molecular protonic devices acting as proton wires, rectifiers, charge separation components, etc., represent highly significant goals in the development of information handling systems based on ionic species. They deserve active synthetic and physico-chemical studies. 

In contrast to the LS3 pore, the water molecules were frozen in the tetrameric LS2 pore, with diffusion coefficients of zero. They were found to be aligned antiparallel to the helix dipole caused by the orientation of the hydroxyl groups of the serine residues. This enabled formation of a water wire network important for the transport of protons by the proton wire or Grotthiis mechanism. 

The percolation model suggests that it may not be necessary to have a rigid geometry and definite pathway for conduction, as implied by the proton-wire model of membrane transport (Nagle and Mille, 1981). For proton pumps the fluctuating random percolation networks would serve for diffusion of the ion across the water-poor protein surface, to where the active site would apply a vectorial kick. In this view the special nonrandom structure of the active site would be limited in size to a dimension commensurate with that found for active sites of proteins such as enzymes. Control is possible conduction could be switched on or off by the addition or subtraction of a few elements, shifting the fractional occupancy up or down across the percolation threshold. Statistical assemblies of conducting elements need only partially fill a surface or volume to obtain conduction. For a surface the percolation threshold is at half-saturation of the sites. For a three-dimensional pore only one-sixth of the sites need be filled. 

Frank,R.A.,Titman, C. M.,Pratap,J.V.,Luisi, B.F., and Perham, R.N. (2004) A molecular switch and proton wire synchronize the active sites in thiamine enzymes. Science306, 872-876. 

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