Using DNA in gel extract kept at -20ºC - (Oct/08/2009 )

Hi,

I have previously done PCR, electrophoresis, gel excision & purification on my DNA sample and ligated some of the purified DNA into my desired vector. All's fine - plasmid extraction & sequencing.

My question is, I still have some leftover purified DNA sitting in the -20ºC freezer. Can I go ahead & do another round of ligation and/or do I have to do any prep work to increase their "efficiency". I read that it is best to do ligation when the DNA is fresh; my samples have been idling in the freezer for >1 month.

I welcome all suggestions, advice, potions etc.

Cheers.

What is your DNA stored in? DNA in TE, frozen, will probably be pretty much in the same condition you started with, modulo some freeze/thaw damage. If it it in water or (worse) with Mg++ or other metal salts present, then lots of bad things can happen.

Just do it! I kept my DNA in the -20ºC freezer for about 2 month. I do a ligation with it, and the result is good.