title: Mobility of molecules and ions solubilized in protein gels: diffusion in the thick fraction of hen egg white.
abstract: The thick fraction of hen egg white is a protein hydrogel with an immeasurably high viscosity composed of ∼90% water that can serve as a model system for mammalian mucous membrane. Measurements of the rate constants of diffusion-controlled reactions occurring within the gel (and corresponding activation energies) and electric conductivity revealed that the thick fraction of egg white can be envisioned as a 3D network comprising hydrated protein molecules (held by intermolecular S-S bridges) surrounded by water pools and channels (of nonuniform diameters) that have a microviscosity that is very similar to that of bulk water. This was corroborated by differential scanning calorimetry measurements that revealed that 16% of water is bound to proteins. The melting kinetics of ice crystallites (produced from the freezable water) indicates nonhomogeneous water pool size.
authors.affiliation: Department of Chemistry, The Pennsylvania State University, University Park, PA 16802, USA.
authors.forename: Keith M
authors.initials: KM
authors.lastname: Krise
authors.forename: Bratoljub H
authors.initials: BH
authors.lastname: Milosavljevic
mesh_terms: D000818:Animals; D001692:Biological Transport; D002152:Calorimetry, Differential Scanning; D002645:Chickens; D004058:Diffusion; D004529:Egg White / Q000737:chemistry*; D004553:Electric Conductivity; D005615:Freezing; D020100:Hydrogels / Q000737:chemistry / Q000378:metabolism*; D007053:Ice; D007477:Ions / Q000378:metabolism*; D007700:Kinetics; D049449:Luminescence; D008163:Luminescent Measurements; D008954:Models, Biological; D009092:Mucous Membrane / Q000378:metabolism*; D013816:Thermodynamics; D014783:Viscosity; D014867:Water / Q000737:chemistry / Q000378:metabolism*
chemical_list: D020100:Hydrogels; D007053:Ice; D007477:Ions; D014867:Water