Hi, I extract protein from beans. My extraction solution contains SDS, glycerol, Na2S2O5, TrisHCL and protease inhibitor. After adding the solution, I centrifuge the samples for 10-15 minutes. Then I remove the tissue, and I got a solution. However, after I store it in the freezer, there is a precipitate at the bottom. What is that and will it affect my proteins? Thank you.
I suppose the precipitate does not solubilize back when temperature is increased. It is most likely proteins that precipitated out due to the decrease in temperature. Analyze the precipitate using SDS-PAGE to corroborate this.
The way you freeze the sample can have an effect on the formation of precipitate. If the sample is simply placed in the freezer and allowed to freeze slowly, the solutes can become concentrated. If the solubility of any of the solutes is exceeded, precipitate will form. Samples should be frozen very quickly to avoid the separation of solutes from ice. This can be done by using a dry ice/acetone, dry ice/ethanol, or liquid nitrogen bath, and division of the sample into small aliquots. Also, it is better to store the samples at -80 or in liquid nitrogen rather than -20, because this prevents sublimation of the ice, which dries the sample out at the surface.
- Badges
- Science topic
- Similar topics
- Biological Science
- Biota
- Eukaryota
- Fungi