Qiaex problems

K.D. James mbkdj at s-crim1.dl.ac.uk
Tue Feb 20 09:18:47 EST 1996

John Stebbins (stebbin1 at pilot.msu.edu) wrote:

: We use Qiaex II from Qiagen to isolate DNA fragments from agarose for the
: purposes of ligation.  We have had LOTS of problems getting our ligations
: to work.  Has anybody else had similiar problems?  Has anybody figured out
: how to correct the problem.  I realize one correction would be to use a
: different method to isolate DNA from agarose.  Anybody have a favorite
: alternative?

: Thanks

: John Stebbins 

	When I used this I had a hopeless time with the ligations, but on
checking them on a gel I found that _all_ the DNA (including vector not
prepped with Qiaex) had vanished. I can only assume that some of the resin
was carried over into the ligation, adsorbing all my precious DNA during
the incubation.
	Next time I filtered the Qiaex eluate through a spin column of
packed, siliconised glass wool before adding to the ligation. Everything
then worked fine. I now use Qiaquick in preference as it is based on a
column similar to those in Qiapreps. I've used that successfully to clone
from a bacterial genome.

--Keith James

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