The effect of water plasticization on the molecular mobility and crystallization tendency of amorphous disaccharides.

Purpose: To study how water plasticization affects the molecular mobility and crystallization tendency of freeze-dried trehalose, sucrose, melibiose and cellobiose.

Methods: Freeze-dried disaccharides were subjected to different relative humidity atmospheres and their physical stabilities were evaluated. Lyophilizate water sorption tendencies and glass transition temperatures were modeled using Brunauer-Emmett-Teller (BET) and Gordon-Taylor (GT) equations, respectively.

The use of disaccharides in inhibiting enzymatic activity loss and secondary structure changes in freeze-dried β-galactosidase during storage.

Purpose: The purpose of this study is to show how disaccharides differ in their ability to protect lyophilized β-galactosidase from enzymatic activity loss and secondary structure changes during storage.

Methods: β-galactosidase was lyophilized with trehalose, sucrose, cellobiose or melibiose at 2:1, 20:1 and 40:1 excipient/protein weight ratios, and stored up to 90 days at 45 °C. Protein enzymatic activity was studied using o-nitrophenyl-β-D-galactopyranoside cleavage test, and its secondary structure in lyophilizates analyzed using Fourier transform infrared spectroscopy.