VITRIFICATION EFFECTS IN WATER PROTEIN SYSTEMS

The method of differential diathermic calorimetry was used to obtain the curves of release and absorption of heat in water-protein systems. The influences of the rates of cooling and heating and the influence of annealing on the state of a water-lysozyme system at different hydration degrees h=0.1-0.7 g/g were studied. Experiments have demonstrated that at considerably large rates of cooling there are observed the effects of vitrification of water-protein systems, i.e. the stabilization of a metastable, nonequilibrium structure of system. Decrease of the cooling rate or annealing transforms more of the system into an equilibrium state, increasing the degree of globular crystallinity to more than 70%. Therefore low-temperature experiments with water-protein systems aimed at obtaining functionally important information (i.e. important also at room temperatures) should be performed with slowly cooled or with annealed systems.