title: Quantifying the diffusion of membrane proteins and peptides in black lipid membranes with 2-focus fluorescence correlation spectroscopy.
abstract: Protein diffusion in lipid membranes is a key aspect of many cellular signaling processes. To quantitatively describe protein diffusion in membranes, several competing theoretical models have been proposed. Among these, the Saffman-Delbrück model is the most famous. This model predicts a logarithmic dependence of a protein's diffusion coefficient on its inverse hydrodynamic radius (D ∝ ln 1/R) for small radius values. For large radius values, it converges toward a D ∝ 1/R scaling. Recently, however, experimental data indicate a Stokes-Einstein-like behavior (D ∝ 1/R) of membrane protein diffusion at small protein radii. In this study, we investigate protein diffusion in black lipid membranes using dual-focus fluorescence correlation spectroscopy. This technique yields highly accurate diffusion coefficients for lipid and protein diffusion in membranes. We find that despite its simplicity, the Saffman-Delbrück model is able to describe protein diffusion extremely well and a Stokes-Einstein-like behavior can be ruled out.
authors.affiliation: III. Institute of Physics, Georg-August-University Göttingen, Göttingen, Germany.
authors.forename: Kerstin
authors.initials: K
authors.lastname: Weiß
authors.forename: Andreas
authors.initials: A
authors.lastname: Neef
authors.forename: Qui
authors.initials: Q
authors.lastname: Van
authors.forename: Stefanie
authors.initials: S
authors.lastname: Kramer
authors.forename: Ingo
authors.initials: I
authors.lastname: Gregor
authors.forename: Jörg
authors.initials: J
authors.lastname: Enderlein
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry / Q000378:metabolism*; D004058:Diffusion; D008051:Lipid Bilayers / Q000737:chemistry / Q000378:metabolism*; D008565:Membrane Proteins / Q000737:chemistry / Q000378:metabolism*; D008969:Molecular Sequence Data; D010455:Peptides / Q000737:chemistry / Q000378:metabolism*; D013050:Spectrometry, Fluorescence
chemical_list: D001426:Bacterial Proteins; D008051:Lipid Bilayers; D008565:Membrane Proteins; D010455:Peptides