title: Partitioning and diffusion of proteins and linear polymers in polyacrylamide gels.
abstract: The equilibrium partition coefficient (K) and diffusion coefficient (Dgel) of two proteins and two linear polymers were measured as a function of polymer content of a 2.7% cross-linked polyacrylamide (PA) gel. The gel concentration, expressed as a volume percentage of PA in the gel (phi), varied between 0 and 14%. The measurements were made by fluorescence spectroscopy; fluorescent dyes were covalently attached to the macromolecules. The dependence of K on phi for the proteins agrees with a model of the gel network as randomly placed, impenetrable rods. The diffusion data are interpreted in terms of an effective medium theory for the mobility of a sphere in a Brinkman fluid. Using values of the Brinkman parameter in the literature, the effective medium model with no adjustable parameters fits the diffusion data for the proteins very well but underpredicts Dgel for the linear polymers. The gel effect on partitioning is significantly greater than that on diffusion. The permeability (KDgel) of bovine serum albumin decreased by 10(3) over the range phi = 0 --> 8%, and the ratio of permeabilities for ribonuclease compared to BSA increased from 2 to 30.
authors.affiliation: Department of Chemical Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, USA.
authors.forename: J
authors.initials: J
authors.lastname: Tong
authors.forename: J L
authors.initials: JL
authors.lastname: Anderson
mesh_terms: D000180:Acrylic Resins; D000818:Animals; D055592:Biophysical Phenomena; D001703:Biophysics; D002417:Cattle; D004058:Diffusion; D005456:Fluorescent Dyes; D005782:Gels; D066298:In Vitro Techniques; D008970:Molecular Weight; D010539:Permeability; D011092:Polyethylene Glycols / Q000737:chemistry / Q000302:isolation & purification; D011108:Polymers / Q000302:isolation & purification*; D011506:Proteins / Q000302:isolation & purification*; D012259:Ribonuclease, Pancreatic / Q000302:isolation & purification; D012710:Serum Albumin, Bovine / Q000302:isolation & purification; D013050:Spectrometry, Fluorescence
chemical_list: D000180:Acrylic Resins; D005456:Fluorescent Dyes; D005782:Gels; D011108:Polymers; D011506:Proteins; C016680:polyacrylamide gels; D012710:Serum Albumin, Bovine; D011092:Polyethylene Glycols; D012259:Ribonuclease, Pancreatic