Thermoanalytical characterization of high molecular weight glutenin subunits: Water effect on their glass transition

The thermal behaviour of the high Mr glutenin subunits (a group of storage proteins in wheat grains) 1Dx5, 1Bx7, 1Dx2, 1Bx20, 1Dy12, 1Bx6 and 1Dy10, was investigated using Differential Scanning Calorimetry and Thermogravimetric Analysis. Also included in these studies, for comparison, was a Mr 58 000 peptide (58 K) derived from the repetitive domain of subunit 1Dx5 and expressed in Escherichia Coli. The plasticizing effect of water on each protein was investigated. When submitted to the calorimetric analysis, the high Mr glutenin subunits exhibited a glass transition phenomenon that was affected by the water content. As expected, the glass transition temperature decreased as the water content was increased.