Stability of proteins stored at -80 degrees

Protein Chemistry Protein Isolation / Purification
1

Hello, I have a question regarding how long I can store proteins at -80 degrees. Forever? Two years ago, I purified some proteins which I keep in the freezer and use to make protein complexes that I isolate with gel filtration. At the first experiment, I got a nice yield of protein complex. But for every time I have repeated the experiment since then, the yield has become lower and lower. And the amount of aggregated and misassembled fractions has become higher. I don’t know if this is because the proteins become less and less stable upon storage, or if the gel filtration column is getting older. As I am using the same protocol.

Any ideas?

2

Dear Barry

Proteins are degraded at even -80C although the rate of degradation is slower. With your post it is looking as if you are using the same aliquot over and again. Whenever your store your protein, store it in aliquots that are to be used for one analysis and avoid the repeat Freeze-Thaw Cycle. Every time you thaw your protein sample, there is bound to be some degradation. Also it is recommended to quickly thaw your same than gradual increase of temperature

1 Like