Strange problems with Invitrogen TOPO vectors Reply-2

Dr. Duncan Clark Duncan at
Wed Oct 6 04:25:21 EST 1999

In article <37FA7843.852D3541 at>, Earl Blewett
<blewett at> writes
>We use rTth for the amplification, gel purify the product, add A residues with
>Taq and wizard-prep it. The final product is a clean band when run on a gel.

Why add Taq?

Tth like all other Thermus polymerase (Tfl, Tub, Taq, TseC, TspB, Tbr,
Tfi etc.) has an integral single base terminal transferase activity,
providing you do the extra 5-10mins final extension. Without that extra
extension a lower proportion of the final product has the overhang (a
quite old NAR single page tech tips reference - and I know I don't
remember which one).

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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