DSC Confirmation That Vitrification Is Not Necessary for Stabilization of the Restriction Enzyme EcoRI Dried with Saccharides

The glass transition temperature (T(g)) of preparations of the restriction enzyme EcoRI, vacuum-dried in the presence ofsucrose, trehalose, or raffinose, was determined using differential scanning calorimetry. T(g) values were well below those expected for lowmoisture sucrose, trehalose, or raffinose, and this was attributed to the presence of glycerol (a plasticizer), which was a main component of the restriction enzyme preparation. This was verified by determining the glass transition temperature of glycerol, which was found to be (onset value) -77 °C. Present results confirmed that vitrification (i.e., glass formation) was not necessary for enzyme protection in present low-moisture saccharide systems. As shown in previous work, enzyme EcoRI was very stable stored at 37/45 °C in spite of the fact that sugar matrices were completely rubbery, as unequivocally demonstrated in the present work.