Help recovering 200 bp DNA fragment

Colin Rasmussen colin_rasmussen at darwin.biochem.ualberta.ca
Sun Aug 6 23:49:09 EST 1995


In article <3vu692$3e5 at mserv1.dl.ac.uk>, "Sergey V. Orlov"
<Serge at bio.iem.ras.spb.ru> wrote:

>      Hi, Harshinee.
> 
> A.  There is a simple and very  efficient  method  for  cleaing  and
> concentrating of nucleic acids 

An even simpler method is to add 20 ug of glycogen (you can get it from
BMB) to the samples prior to ethanol precipitation.  The glycogen forms a
visible pellet which also contains the DNA, and does not affect subsequent
reactions such as restriction digests, ligation etc.  This works very well
with small fragments.  We usually purify smaller fragments on PAGE gels,
cut out the slice, place in a tube and add 250 ul TE + 30 ul 3M NaOAc and
allow the fragment to elute overnight at 37°C.  We then EtOH precipitate
and get very good recoveries.  We usually don't even add the glycogen but
centrifuge for 10-15 minutes which as BRL showed years ago is really the
critical factor in DNA precipitation.

Colin



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