title: Profiling of dynamics in protein-lipid-water systems: a time-resolved fluorescence study of a model membrane protein with the label BADAN at specific membrane depths.
abstract: Profiles of lipid-water bilayer dynamics were determined from picosecond time-resolved fluorescence spectra of membrane-embedded BADAN-labeled M13 coat protein. For this purpose, the protein was labeled at seven key positions. This places the label at well-defined locations from the water phase to the center of the hydrophobic acyl chain region of a phospholipid model membrane, providing us with a nanoscale ruler to map membranes. Analysis of the time-resolved fluorescence spectroscopic data provides the characteristic time constant for the twisting motion of the BADAN label, which is sensitive to the local flexibility of the protein-lipid environment. In addition, we obtain information about the mobility of water molecules at the membrane-water interface. The results provide an unprecedented nanoscale profiling of the dynamics and distribution of water in membrane systems. This information gives clear evidence that the actual barrier of membranes for ions and aqueous solvents is located at the region of carbonyl groups of the acyl chains.
authors.affiliation: Laboratory of Biophysics, Wageningen University, 6703 HA Wageningen, The Netherlands.
authors.forename: Rob B M
authors.initials: RB
authors.lastname: Koehorst
authors.forename: Sergey
authors.initials: S
authors.lastname: Laptenok
authors.forename: Bart
authors.initials: B
authors.lastname: van Oort
authors.forename: Arie
authors.initials: A
authors.lastname: van Hoek
authors.forename: Ruud B
authors.initials: RB
authors.lastname: Spruijt
authors.forename: Ivo H M
authors.initials: IH
authors.lastname: van Stokkum
authors.forename: Herbert
authors.initials: H
authors.lastname: van Amerongen
authors.forename: Marcus A
authors.initials: MA
authors.lastname: Hemminga
mesh_terms: D015081:2-Naphthylamine / Q000031:analogs & derivatives* / Q000378:metabolism; D002462:Cell Membrane / Q000737:chemistry* / Q000378:metabolism; D005456:Fluorescent Dyes / Q000378:metabolism; D006860:Hydrogen Bonding; D007091:Image Processing, Computer-Assisted; D008027:Light; D008051:Lipid Bilayers / Q000737:chemistry* / Q000378:metabolism*; D008565:Membrane Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D008958:Models, Molecular; D012997:Solvents / Q000737:chemistry; D013050:Spectrometry, Fluorescence; D013194:Staining and Labeling; D013997:Time Factors
chemical_list: C122155:6-bromoacetyl-2-dimethylaminonaphthalene; D005456:Fluorescent Dyes; D008051:Lipid Bilayers; D008565:Membrane Proteins; D012997:Solvents; D015081:2-Naphthylamine