Proteins are complex macromolecules that perform specialized roles in the cell, requiring them to maintain their specific structures. Because of the nature of the bonds that hold the secondary and tertiary structures in place, some proteins are very unstable when removed from their natural environment, whether that environment is in the cytoplasm of the cell or locked within the cell membrane.
Standard protein purification methods generally include specific buffer and storage conditions that are necessary to ensure the protein remains soluble and intact, maintaining its specific activity. Sample contamination can cause proteolysis (decomposition by protease enzymes), and improper storage conditions may result denaturing of proteins which may form aggregates or simply lose activity. Several approaches are used for preventing loss of protein activity in purified samples:
- Storage at low temperatures
- Lyophilization
- Additives such as cryoprotectants (glycerol), protease inhibitors, antimicrobial agents, metal chelators (EDTA) and reducing agents (dithiothreitol; DTT)
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