DNA storage: TE vs water - (Mar/27/2007 )
I read several times that it is recommended to store DNA (any kind of DNA?) in TE rather then water. However, the EDTA inhibits enzyme reactions, right? So how can I use DNA that has been stored in TE for digests or ligations? Does the EDTA not hurt then?
And can I elute the DNA from miniprep colums in TE instead of water or the elution buffer from the kit?
How do you guys handle that?
I would greatly appreciate your help!
TE has 1 mM EDTA. A typical reaction like RE digestion might have 2 ug of DNA in a 50 ul reaction. If the concentration of our miniprep DNA is 200 ng/ul, then this is 10 ul of your RE volume. The final restriction reaction will then be 200 uM EDTA. Now, look at the composition of a typical RE buffer. 1x NEB buffer 3, for example, has 10 mM MgCl2. The EDTA will chelate 0.2 mM of this, for a final Mg++ concentration of 9.8 mM. You can see that this has hardly any effect. Similar reasoning applies to most other DNA applications. The advantages of storing DNA in TE far outweigh the almost inconsequential effects of EDTA in the final enzyme reaction solution.
TE is perfectly fine for eluting DNA from miniprep columns of any kind. The only issue there is low salt concentration, and TE has no salt.
Some people make a version of TE with lower EDTA concentrations, but this is seldom an issue, as you can see.