title: Protein self-diffusion in crowded solutions.
abstract: Macromolecular crowding in biological media is an essential factor for cellular function. The interplay of intermolecular interactions at multiple time and length scales governs a fine-tuned system of reaction and transport processes, including particularly protein diffusion as a limiting or driving factor. Using quasielastic neutron backscattering, we probe the protein self-diffusion in crowded aqueous solutions of bovine serum albumin on nanosecond time and nanometer length scales employing the same protein as crowding agent. The measured diffusion coefficient D(ϕ) strongly decreases with increasing protein volume fraction ϕ explored within 7% ≤ ϕ ≤ 30%. With an ellipsoidal protein model and an analytical framework involving colloid diffusion theory, we separate the rotational D(r)(ϕ) and translational D(t)(ϕ) contributions to D(ϕ). The resulting D(t)(ϕ) is described by short-time self-diffusion of effective spheres. Protein self-diffusion at biological volume fractions is found to be slowed down to 20% of the dilute limit solely due to hydrodynamic interactions.
authors: Institut für Angewandte Physik, Universität Tübingen, 72076 Tübingen, Germany.
authors: Felix
authors: F
authors: Roosen-Runge
authors: Marcus
authors: M
authors: Hennig
authors: Fajun
authors: F
authors: Zhang
authors: Robert M J
authors: RM
authors: Jacobs
authors: Michael
authors: M
authors: Sztucki
authors: Helmut
authors: H
authors: Schober
authors: Tilo
authors: T
authors: Seydel
authors: Frank
authors: F
authors: Schreiber
mesh_terms: D004058:Diffusion; D046911:Macromolecular Substances / Q000737:chemistry*; D008956:Models, Chemical; D033363:Neutron Diffraction; D012399:Rotation; D012710:Serum Albumin, Bovine / Q000737:chemistry*; D014867:Water / Q000737:chemistry
chemical_list: D046911:Macromolecular Substances; D014867:Water; D012710:Serum Albumin, Bovine