eluation of small DNA fragments from gel

[grey at em.uni-frankfurt.de]

Matthias Wahl <matthias.wahl at gsf.de> wrote:

>Could anyone tell me a good method for eluting small DNA fragments
>(20-30bp) from Polyacrylamide? It could also be a method for eluting
>from Agarose (Metaphor etc). My problem is, that most methods use
>temperatures, at which such small fragments will melt.

>I currently use 12% PAGE, and elute just by incubating together with
>buffer for >2h at 37=B0C and afterwards just filter away the
>polyacrylamide. My problem is that I only have a very low efficiency in
>a subsequent ligation step. Propably I carry over some contamination
>from the polyacrylamide. Is this likely that remaining polyacrylamide is
>inhibiting ligation reactions, or do I just have some impure reagents
>for making the gel.

>I also looked for some commertial kits for purifying the eluted DNA but
>they are not suitable fur fragments of this size.

>Thanks in advance

>Matthias Wahl
Matthias Wahl <matthias.wahl at gsf.de> wrote:

>Could anyone tell me a good method for eluting small DNA fragments
>(20-30bp) from Polyacrylamide? It could also be a method for eluting
>from Agarose (Metaphor etc). My problem is, that most methods use
>temperatures, at which such small fragments will melt.

Hi Matthias,

Try this one (see below). For small fragments, its working great. 
No heat required. The filter disks can be obtained from Schleicher &
Schuell (normally used for antibiotics). Good luck
-------------------------------------------------------------------------------------------------------
Grey M, Brendel M
Curr Genet 1992 Jul;22(1):83-4 
"Rapid and simple isolation of DNA from agarose gels"