Glass Transition in a BSA-Water System : Application of Enthalpy Relaxation Rate Measurement Using Adiabatic Calorimetry(Papers presented at the 51^<st> Annual Meeting)

Abstract

The enthalpy relaxation rates of freeze-dried bovine serum albumin (BSA) with or without a small amount of water were investigated in a temperature range of 50-300K by using adiabatic calorimetry. While not found in anhydrous BSA, spontaneous enthalpy relaxation was observed due to a glass transition from 120K to 180K in BSA with 1.85% moisture. A typical glass transition temperature in the wide enthalpy relaxation range was estimated as 155K based on an empirical interpretation. Since globular proteins with a small amount of water are generally immobilized at room temperature, this low-temperature glass transition is interpreted as attributed to the rearrangement of water molecules within BSA.