title: Membrane surface potential of Spiroplasma floricola.
abstract: Anionic charges, cytochemically identified as lipid phosphate groups, cover the outer membrane surface of Spiroplasma floricola. They induce a negative membrane surface potential which affects the distribution of ions, including protons. Accordingly, the pH at the interface differs from the bulk pH. By using the fluorescent lipoid pH indicator 4-heptadecyl-7-hydroxycoumarin, the pH at the membrane surface was determined. From the difference of the bulk and the interfacial pH the membrane surface potential of S. floricola was calculated to be phi = -118 mV.
authors.affiliation: Institut für Medizinische Mikrobiologie, Klinikum der Justus Liebig Universität, Giessen, FRG.
authors.forename: U
authors.initials: U
authors.lastname: Schummer
authors.forename: H G
authors.initials: HG
authors.lastname: Schiefer
mesh_terms: D004594:Electrophysiology; D006863:Hydrogen-Ion Concentration; D008564:Membrane Potentials; D013149:Spiroplasma / Q000502:physiology*; D013499:Surface Properties; D014468:Umbelliferones
chemical_list: D014468:Umbelliferones; C031827:4-heptadecylumbelliferone