35S-labelled oligo purification

Dr. Duncan Clark Duncan at nospam.demon.co.uk
Wed Feb 2 12:03:20 EST 2000

In article <879l1j$ahl$1 at beta.qmw.ac.uk>, Danny McLaughlin
<D.P.McLaughlin at mds.qmw.ac.uk> writes
>Tried salt equilibration up to 150 and then 500 mM, then STE and STET and
>NOTHING seemed to do the trick.  Basically we have decided that these
>columns are not useful for this purpose (35S labelled oligos) and will steer
>clear of them - I advise other to think carefully about using them too!

Could it be that as you have tail lengths of maybe 50-100bp that these
are getting into the pores of the sephadex beads and wrapping themselves
around the bead. The dATP is supposed to get slowed down by migration
through the pores whilst the larger molecule goes around so what I am
suggesting looks wrong. However if the tailed oligo gets trapped this
way the vortexing may free them as you are finding (maybe by shearing?).

There again who cares about the research if you need to get the money
for new label and you if you have better method anyway!

The problem with being on the cutting edge is that you occasionally get 
sliced from time to time....

Duncan Clark
DNAmp Ltd.
Tel: +44(0)1252376288
FAX: +44(0)8701640382

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