I am using an aTC inducible TetR expression system, and so wish to use aTC for protein induction in E.coli HM0079.
I know that when dissolved in water, aTC stock is only stable for around 24 hours. However, if I make a stock aTC solution in distilled water, aliquot it and store at -20 °C straight away, will it remain viable for induction at later dates?
Or, is it necessary to use an organic solvent such as DMSO/DMF for storage over a few weeks?
Also, the aTC crystals are stored in Argon gas as aTC is hygroscopic. After opening the container and preparing stocks, should I store the remaining crystals at - 20°C?
Or, can I wrap the container in Parafilm to create a seal?
The product should be frozen below 0°C and protected from light and moisture. In these conditions, the product has been shown to retain activity for 4 years. Stock solutions should be stored at -20°C and are stable at 37°C for 4 days. Sigma-Aldrich
Thank you for your answer; I made the stock solution in ethanol, which I stored at -20 C. I ended up sealing the remaining crystals in parafilm and also storing at -20 C. One thing to note is that the crystals must be allowed to reach room temperature before opening, or condensation will form on the crystals if opened while still cold.
Dan Williams- Jones When you made your stock solution in ethanol, did you use ethanol 50% or 70%?
Thank you.
Fábio Muniz de Oliveira I believe that I used 100% ethanol when making my stock (though that was some time ago, and I am no longer working on the same project), but it may be fine to use the dilutions you mentioned.
Thanks.
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