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 e nzyme EcoRI, vacuum-dried in the presence of sucrose, trehalose, or raffino se, was determined using differential scanning calorimetry. T-g values were well below those expected for low-moisture sucrose, trehalose, or raffinos e, and this was attributed to the presence of glycerol (a plasticizer), whi ch was a main component of the restriction enzyme preparation. This was ver ified by determining the glass transition temperature of glycerol, which wa s found to be (onset value) -77 degrees C. Present results confirmed that v itrification (i.e., glass formation) was not necessary for enzyme protectio n in present low-moisture saccharide systems. As shown in previous work, en zyme EcoRI was very stable stored at 37/45 degrees C in spite of the fact t hat sugar matrices were completely rubbery, as unequivocally demonstrated i n the present work.