Re: [DIYbio] Re: Do enzymes really need to be "frozen"?

8:27 AM |

Storing enzymes in glycerol in a freezer is all about thermodynamics. When a protein(enzyme) are at higher temperatures it has access to a wider variety of conformational states it can inhabit according to Boltzmann and physics. What this means is that the protein can cross over energy barriers into disordered or non-functional conformations. This is why proteins are always stored at or around -20C in glycerol. You don't want to freeze proteins because the changes in the organization of water can effect the structure and conformation of the protein. You do not want to store proteins at -80C because proteins can also cold denature http://waterinbiology.uchicago.edu/Papers_files/fluc-cold_jp075928t-PJR.pdf . So the complete coldest temperature might not be the best. It is very reasonable to think that some proteins can last a long time at room temperature but in general it is better to store at 4C or at -20C in glycerol.


-20C is your average freezer and 4C is your average refrigerator. If one cannot store at -20C then store at the next lowest temperature 4C, this will help increase the lifetime of the protein. 

A single Power outages should not drastically effect the lifetime of your enzyme. Taking the enzyme from -20C to ~room temperature often would probably effect it more if one is not using it on ice or even if one is using ice.

Storage guidelines for things in molecular biology are general guidelines for safe and practical science. Obviously these rules can be broken just understand why they can be broken and when it is reasonable to break them and everything will be ok. However, as a general guideline for beginners one should be as uptight as possible becuase it makes troubleshooting that much easier.

On Sunday, March 24, 2013 8:58:07 AM UTC-5, Mega wrote:
There are three different types of restriction enzymes. Type I cuts DNA at random locations as far as 1000 or more base-pairs from the recognition site. Type III cuts at approximately 25 base-pairs from the site. Types I and III require ATP and may be large enzymes with multiple subunits. Type II enzymes, which are predominantly used in biotechnology, cut DNA within the recognized sequence without the need for ATP, and are smaller and simpler. 


So no ATP for molecular cloning restriction enzymes!! 

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