Freeze Drying Of Proteins
1. What is the purpose of protein lyophilization?
Proteins are sensitive to heat, and lyophilization can retain the activity of most proteins, improve protein stability and prolong storage time, and reduce shipping costs as well.
2.What is the effect of freeze drying of proteins?
Freeze-drying may cause loss of active part of the protein, aggregation and other denaturation problems. However, these negative effects can be minimized by adding protective agents and controlling various conditions of lyophilization.
3.Why add a protective agent to the solution before protein lyophilization?
Protectants are used to protect proteins during freeze-drying and storage.
Note: For most proteins, they can only be stored at 4 ℃ for a short period of time (about 1 week) after resuspending. For long-term storage, please prepare a diluent (which must contain carrier protein, such as 0.1% BSA, 5% HSA, or 10% FBS), and then freeze and store in packages under -20℃ or -80℃. Be sure to avoid repeated freezing and thawing, because each freezing and thawing will cause partial inactivation of the protein
4. What are the common protective agents?
The most commonly-used protective agents for protein lyophilization are sugars and polymer compounds. Sucrose and trehalose are the representatives of sugars. Serum albumin is that of polymer compounds. Serum albumin can be used as a cryoprotectant or a drying protector during freeze drying of proteins. Its protective effect on proteins has been widely recognized, but it may hinder its application because it may contain pathogens. At present, recombinant human albumin is generally used instead of serum albumin as a protein protective agent.
5. How to reconstitute dry protein powder when the freeze drying of proteins has finished?
It is recommended to use filtered, sterile purified water as the reconstitution solvent. Add purified water to the recommended volume, and gently shake the vial to make the protein completely soluble.
Note: Avoid violent shaking. Shake the vial gently to dissolve the protein evenly.
PBS or other buffers can also be used as the reconstitution solvents when the protein lyop
hilization is finished. because the salt in PBS can be neglected in the case of small volumes. If possible, you can compare the effects of the two reconstituted solvents.
6. Is freeze drying suitable for all proteins?No, freeze drying of proteins have restrictions. Proteins associated with cell membranes are easily destroyed by freeze-drying. Moreover, not all proteins can maintain stability after lyophilization, and some may be denatured, thereby reducing their usefulness and ability to re-dissolve. Pay attention to the protein characteristics when you decide to implement protein lyophilization.
7. Why are some proteins labeled?
The original purpose of using protein tags is for protein purification. In addition, it can be used to detect proteins in certain tests. Fc tag has the function of stabilizing fusion protein. And this tag can also form dimers autonomously, so it can help fusion proteins, especially receptors, to form active dimers.
8. Will the label affect protein activity?
For some applications, small tags, such as histidine tags, may have a small effect on protein activity, so there is no need to remove them. If you are concerned about whether the label will affect protein activity, you can consult customer service for inquiries. In addition, some protein tags can be removed by enzyme.
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