title: Determination of the glass-transition temperature of proteins from a viscometric approach.
abstract: All fully hydrated proteins undergo a distinct change in their dynamical properties at glass-transition temperature Tg. To determine indirectly this temperature for dry albumins, the viscosity measurements of aqueous solutions of human, equine, ovine, porcine and rabbit serum albumin have been conducted at a wide range of concentrations and at temperatures ranging from 278 K to 318 K. Viscosity-temperature dependence of the solutions is discussed on the basis of the three parameters equation resulting from Avramov's model. One of the parameter in the Avramov's equation is the glass-transition temperature. For all studied albumins, Tg of a solution monotonically increases with increasing concentration. The glass-transition temperature of a solution depends both on Tg for a dissolved dry protein Tg,p and water Tg,w. To obtain Tg,p for each studied albumin the modified Gordon-Taylor equation was applied. This equation describes the dependence of Tg of a solution on concentration, and Tg,p and a parameter depending on the strength of the protein-solvent interaction are the fitting parameters. Thus determined the glass-transition temperature for the studied dry albumins is in the range (215.4-245.5)K.
authors.affiliation: Department of Biophysics, Medical University of Silesia, H. Jordana 19, 41-808 Zabrze 8, Poland. Electronic address: monkos@sum.edu.pl.
authors.forename: Karol
authors.initials: K
authors.lastname: Monkos
mesh_terms: D000465:Algorithms; D000818:Animals; D006801:Humans; D008962:Models, Theoretical; D011506:Proteins / Q000737:chemistry*; D012709:Serum Albumin / Q000737:chemistry; D044366:Transition Temperature; D014783:Viscosity
chemical_list: D011506:Proteins; D012709:Serum Albumin
keywords: Albumin; Avramov's model; Glass-transition temperature; Gordon–Taylor equation; Viscosity