On the Possibility of Indirect Determination of the Glass Transition Temperature of Proteins from Viscosity Measurements and Avramov's Model

• Published in: Current Topics in Biophysics 2015-01, Vol.37 (1), p.63-70
• Main Author: Monkos, Karol
• Format: Article
• Language: English
• Subjects: Aqueous solutions; Eggs; Glass transition temperature; Immunoglobulin G; Interaction parameters; Lactoglobulin; Lysozyme; Mathematical models; Proteins; Temperature; Temperature dependence; Transition temperatures; Viscosity; Viscosity measurement; β-Lactoglobulin
• ISSN: 2084-1892; 1232-9630; 2084-1892
• DOI: 10.2478/ctb-2014-0076

The paper presents the results of viscosity determinations on aqueous solutions of hen egg-white lysozyme, bovine ß-lactoglobulin, human and porcine immunoglobulin IgG at a wide range of concentrations and at temperatures ranging from 5 C to 55 C. Viscosity-temperature dependence of the proteins solutions is analyzed based on a formula resulting from the Avramov's model. One of the parameters in the Avramov's equation is the glass transition temperature T . It turns out that for all studied proteins, the Tg of the solution increases with increasing concentration. To determine the glass transition temperature of the dry protein Tg,p, a modified form of the Gordon-Taylor equation is used. This equation gives the relationship between Tg and the concentration of the solution, and Tg,p and a parameter dependent on the strength of protein-solvent interaction are fitting parameters. Thus determined the glass transition temperature for the studied dry proteins is in the range from 227.3 K (for bovine ß-lactoglobulin) to 260.6 K (for hen egg-white lysozyme).