title: Interfacial complexes between a protein and lipophilic ions at an oil-water interface.
abstract: The interaction between an intact protein and two lipophilic ions at an oil-water interface has been investigated using cyclic voltammetry, impedance based techniques and a newly developed method in which the biphasic oil-water system is analyzed by biphasic electrospray ionization mass spectrometry (BESI-MS), using a dual-channel electrospray emitter. It is found that the protein forms interfacial complexes with the lipophilic ions and that it specifically requires the presence of the oil-water interface to be formed under the experimental conditions. Furthermore, impedance based techniques and BESI-MS with a common ion to polarize the interface indicated that the Galvani potential difference across the oil-water interface significantly influences the interfacial complexation degree. The ability to investigate protein-ligand complexes formed at polarized liquid-liquid interfaces is thus a new analytical method for assessing potential dependent interfacial complexation using a structure elucidating detection principle.
authors.affiliation: Department of Pharmaceutics and Analytical Chemistry, Faculty of Pharmaceutical Sciences, University of Copenhagen, Universitetsparken 2, DK-2100 Copenhagen, Denmark.
authors.forename: Rune A
authors.initials: RA
authors.lastname: Hartvig
authors.forename: Manuel A
authors.initials: MA
authors.lastname: Méndez
authors.forename: Marco
authors.initials: M
authors.lastname: van de Weert
authors.forename: Lene
authors.initials: L
authors.lastname: Jorgensen
authors.forename: Jesper
authors.initials: J
authors.lastname: Østergaard
authors.forename: Hubert H
authors.initials: HH
authors.lastname: Girault
authors.forename: Henrik
authors.initials: H
authors.lastname: Jensen
mesh_terms: D000327:Adsorption; D025802:Electric Capacitance; D017097:Electric Impedance; D004563:Electrochemistry / Q000379:methods*; D057927:Hydrophobic and Hydrophilic Interactions; D008958:Models, Molecular; D009113:Muramidase / Q000737:chemistry* / Q000378:metabolism; D009821:Oils / Q000737:chemistry*; D011485:Protein Binding; D011487:Protein Conformation; D021241:Spectrometry, Mass, Electrospray Ionization; D013775:Tetraphenylborate / Q000031:analogs & derivatives* / Q000737:chemistry; D014867:Water / Q000737:chemistry*
chemical_list: D009821:Oils; D014867:Water; C030385:tetrakis(4-chlorophenyl)borate; D013775:Tetraphenylborate; D009113:Muramidase