So I was wondering what the best practices for thawing enzymes, RNA and DNA for various purposes. I have always been told to leave them on top of the ice to slowly thaw and avoid degradation. Recently I joined a lab that thaws using the warmth from their finger tips to speed up the process. If anybody knows of literature that has looked into the effects of speed thawing, I would love some more information. Thanks!
enzymes should be stored in glycerol and never frozen just stored at -20 or lower. Thawing warm with gentle mixing is fine since so long as some ice remains the liquid temperature will still be 0C until all of the ice has melted. Enzyme buffers should always be thoroughly mixed after thawing as the salts come out of the ice first on thawing so forms a salt gradient in the tube
Hej,
- https://greenlab.mit.edu/sites/default/files/documents/RNA%20stability.pdf (unfortunately the poster can only be found through google and not through greenlab.mit.edu...)
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Article Short-Term Stability Study of RNA at Room Temperature
- https://www.mlo-online.com/freeze-thaw-cycles-and-nucleic-acid-stability-whats-safe-for-your-samples.php (see the references given there)
Generally it is best to take your samples out of the freezer early enough to let them thaw peacefully ;) If I need samples to thaw quickly (especially DNA and RNA), I gently flick the tubes. Adding a little body heat to DNA samples every now and then won't hurt, but I wouldn't do that to my dear RNA samples. Enzymes usually don't need thawing as already stated by Paul; and for buffers, most manuals include info on how to best handle those to prevent salt precipitation or other unwanted effects.
On a practical note, there is "best practice" and then there is "good enough". Most folks don't want to bother to wait for their DNA (or buffers or other non-temperature sensitive reagents) to thaw and will hold them in their hands, store them in the refrigerator or other methods. Don't add heat to RNA or enzymes since the degradation isn't worth the small time savings.
If everyone in the lab thaws their DNA by holding it and their experiments still work, don't pester them to change what they are doing. Just worry about how you handle your reagents.
Yeah enzymes should be in glycerol stocks, so they don't need to thaw, you want to keep them in the -20C until you need to add it to your reaction (last).
Thawing DNA, you can gently warm it in your hand, its pretty stable. But it thaws fairly fast on ice. For RNA I would never thaw it in my hand, I just feel like RNA is more likely to become unstable and degrade.
Personally I allow everything to thaw on ice, you just have to get out your DNA or RNA 30 minutes before you plan to set up your reaction.
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