Hydrogen-bonded chains with large proton polarizability due to collective proton motion - Pathways for protons in biological membranes

Hydrogen-bonded chains may show very large proton polarizability due to collective proton motion if they are largely symmetrical. This result was first obtained with polylysine + dihydrogenphosphate and with polyglutamic acid + dihydrogenphosphate systems, respectively. These systems cause intense IR continua, demonstrating their large proton polarizability. This proton polarizability was studied in detail with intramolecular hydrogen-bonded systems and results of these studies are extensively discussed in this paper. Such hydrogen-bonded chains are very effective proton pathways in biology. They can easily be regulated by local electrical fields and by specific interactions. Two such pathways are discussed, the one in the L-550 intermediate in the bacteriorhodopsin molecule and the pathway in the F-0 subunit of the ATP synthase.