Do repeated freeze-thaw cycles affect protein activity? - (Mar/02/2006 )
Are there any problems in protein in the repeated passage from -20°C to +15 ? Do they lose their biological activity?
I am not so sure abouth this question, i think yes!?!.However visit this http://support007.com/find.php?value=protein+activity,i think that over there u will find some detailed informations.
Absolutely. Repeated freeze-thaw cycles will damage and potentially denature most enzymes/proteins (this is why most of the commercially available ones are contained in a high percentage of glycerol so they do not freeze at -20). If you have a protein in aqueous buffer then you need to aliquot it into smaller, possibly single-use batches. Just thaw one of these as and when it's needed.
a colleague did some exp of transcription.
ithout freezing she gets a 100activity.
After a standard slow freezing, she got 60% (roughly)
But if she freeze in nitrogen, she got 80%activity.
And after 2 cycles, activity is about 20% in first case and 50% in the second.
These values were not accurately measured but it's estimation.
ithout freezing she gets a 100activity.
After a standard slow freezing, she got 60% (roughly)
But if she freeze in nitrogen, she got 80%activity.
And after 2 cycles, activity is about 20% in first case and 50% in the second.
These values were not accurately measured but it's estimation.
well.. i've came across a drop in my Protein A activity with repeated freeze thaw cycles from -20 deg to rt.. the suggestion to aliquot ur protein is a good one.. i am also doing tht..