Enzymes are lyophilized, or freeze-dried, using a process designed to preserve their activity and stability for long-term storage and transportation. In this process, enzymes are typically dissolved in a buffer solution to maintain their native conformation and functionality. The enzyme solution is then frozen rapidly to form ice crystals, usually by immersion in liquid nitrogen or placing it in a freeze-dryer with pre-cooled shelves. Rapid freezing helps prevent the formation of large ice crystals that could damage the enzyme structure.
After freezing, the frozen enzyme solution undergoes primary drying, where the pressure in the lyophilization chamber is reduced, and heat is applied to induce sublimation. This process removes the frozen water from the enzyme solution, leaving behind a porous matrix of dried enzyme. The primary drying phase is critical for preserving the native structure and activity of the enzyme, as it minimizes the exposure of the enzyme to denaturing conditions.
Following primary drying, the lyophilized enzyme undergoes secondary drying, where residual bound water molecules are removed at slightly elevated temperatures. This additional drying step ensures complete dehydration of the enzyme matrix, further enhancing its stability during storage. Once lyophilization is complete, the dried enzyme is typically sealed in vials or other suitable containers under inert gas to prevent moisture uptake and degradation. Properly lyophilized enzymes can retain their activity and stability for extended periods, making them valuable tools in various biochemical, biotechnological, and industrial applications.