Hi MWt PCR artefact

Dr. Duncan Clark drc at nospam.demon.co.uk
Fri Jul 14 03:51:50 EST 2000

In article <396E5B9F.1F37451A at uow.edu.au>, Mark Dowton
<Mark_Dowton at uow.edu.au> writes
> I would guess that
>it's a bona fide PCR product, but it is far too big (>20 kbases)  to be
>produced in the 2.5 min extension we're giving this (we do have a
>Taq/PFU polymerase mix though). It only appears with ca. 3 mm Mg++ in
>the PCR reaction, much less is produced with 1 mm.  Any ideas?

It will be DNA but I have no idea why it appears. You can get this,
usually as a smear, when doing long PCR. Anything from 100bp right the
way back to the well. There has been a couple of papers in NAR maybe 2
years ago about Taq and Tth being able to do de novo DNA synthesis i.e.
no template or primers in the reaction. No reference to hand.

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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