The term “freeze-dry” is a lay description for the process of lyophilization protein powder. It is the conversion of water from a frozen state to a gaseous state without going through a liquid state. Aliquoting with 25 mM HEPES-KOH, pH 7.2 and 1 mM DTT and 10% weight on volume glycerol is suitable for storage of the reconstituted powder. The freeze-dry process removes moisture from the cells of specimens while the specimens remain frozen.Pigs and the smaller guinea pigs are frequent used as models for humans.
