Storage of protein - -20oC or -80oC? Which one is better? (Dec/17/2006 )

Dear all,

What do u think? -20oC or -80oC? Which one is a better condition for protein storage? Any idea?

Thank you so much!!!

siuchi

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For short-term storage, no real difference. But for longer-term storage, go for -80.

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I saw my proteins degraded even at -80 C° in one week, be careful

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for short term storage can i keep it in 4 c??

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better -80 C.

Store in 4C if u plan to reuse the protien within the same day, else -80C is better.

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it depends on the protein and your needs. some proteins can be stored frozen and they will be as active next month (year, decade, whatever) as they are today. others will denature upon the initial freezing (often due to ice crystal formation). most proteins will be stable at freezer temperatures for long periods of time if they are prevented from freezing (eg: in 50% glycerol). i don't know if those would survive -80C because they will most likely freeze but the glycerol will prevent ice crystal formation, so they may survive intact (dna polymerases and restriction enzymes appear to be stable in the presence of less than 50% glycerol stored at -80C).

we used to store myosin at -20C in 50% glycerol and it was stable for years. we stored calpain at -20C in 50% glycerol and it was stable for months. neither survived freezing (-20C without glycerol).

if you want to know if your own protein is stable then you should try the various conditions on aliquots of the same batch of protein.

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Hello Siuchi

This is protein dependent.

If your protein is relatively small, single domain protein (<30kDa), you should try to 'lyophilize' it. The lyophilized powder can be stored at -20 for years without losing activity (when redissolved).

Alternately, for small single domain proteins, which can refold on their own, you could also just freeze the protein solution in its respective buffer and store at -20C.

If your protein is large, multi-domain protein, there is a high change of proteolytic cleavage and accumulation of proteolytic products over time (predominantly occuring in the exposed flexible hinges between domains). In this case, you can add 50% glycerol and store at -20C for atleast a few months (this time is also very protein specific).

In anycase, it is always best to do a functional assay (activity, etc.,) before you use your stored protein.

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Dear All,

Thx very much for yours reply!!!!

If the protein is single chain antibody which is purified from bacteria, what do you think?

Thanks

siuchi

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I would recommend storing it in the buffer in which you plan to use the antibody, but supplement the buffer with 50% glycerol.
Store at -20C.
Sample will not freeze.
Spin the sample at 10,000X G for 10 min at 4C before use (to remove any aggregates).

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hi! i was browsing this forum because i wanted to learn more about plant protein extraction. what if i wanted to store my leaves before extracting the proteins? do i need to store it at -80C or would 4C be ok? if i add glycerol into the buffer, will it not interfere when i finally do gel filtration? or is there a way to get rid of it? thanks so much!


pls email me at hannahdyoi@gmail.com

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