title: Interfacial air/water proton conduction from long distances by sulfolobus solfataricus archaeal bolaform lipids.
abstract: The stability, structural organization, and the ability to transfer protons long distances have been investigated in monolayers formed from archael bolaform lipids at the air/water interface. The lipids employed were the fractions GroR2Gro (R represents an acyl group with variable chain length typically consisting of 0-4 cyclopentane rings and 40 isoprenoid residues) and GroR2GroNon-Ol (Non-ol represents nonitol) extracted from Sulfolobus solfataricus by hydrolysis of the cytoplasmic membrane. GroR2-GroNon-ol films exhibit a very peculiar behaviour: the monolayer surface pressure increases with time, regardless of its low or high initial value. This finding is related to the possibility of GroR2GroNon-ol molecules to assume an upright (a metastable) or a U-shaped (stable) configuration. In the gaseous state and in the collapsed state of the film, no lateral proton conduction was observed. However, in the pressure range 0 < pi < 25 mN/m for GroR2Gro and 0 < pi < 30 mN/m for GroR2GroNon-ol monolayers, a lateral proton conduction at the air/water interface was observed. The structural organization of these bipolar lipids at the air/water interface can be related to the lateral proton conduction; it is possible to conclude that whatever configuration these lipids may adopt, they are able to structure the air/water interface in a hydrogen bond network that supports lateral proton conduction. This process may be ascribed to a percolation phenomenon occurring when the polar lipid head groups form a structured lattice of hydrogen bonds.
authors.affiliation: Université Paul Sabatier, Toulouse, France.
authors.forename: I
authors.initials: I
authors.lastname: Vilalta
authors.forename: A
authors.initials: A
authors.lastname: Gliozzi
authors.forename: M
authors.initials: M
authors.lastname: Prats
mesh_terms: D000388:Air; D004075:Diglycerides / Q000737:chemistry* / Q000302:isolation & purification; D050356:Lipid Metabolism; D008081:Liposomes; D015394:Molecular Structure; D011312:Pressure; D011522:Protons; D013050:Spectrometry, Fluorescence; D016944:Sulfolobus / Q000378:metabolism*; D013499:Surface Properties; D013729:Terpenes / Q000737:chemistry* / Q000302:isolation & purification; D014867:Water
chemical_list: D004075:Diglycerides; C101522:GroR(2)Gro; C101523:GroR(2)GroNon-ol; D008081:Liposomes; D011522:Protons; D013729:Terpenes; D014867:Water