A Non high fidility 5.3K PCR?

Svetlov Vladimir svetlov at oncology.wisc.edu
Thu Jan 1 08:08:26 EST 1998


In article <34a8df20.1051813 at news.univie.ac.at>, a8803349 at unet.univie.ac.at
(Martin Offterdinger) wrote:


:I think that non high fidelity and large amplicons are somehow
:incompatible, because you simply need quite a high fidelity to get
:large amplicons amplified!
:Martin

I'm afraid that high fidelity has not that much to do with the
amplification of the large fragments. The success of the latter is more
determined by the polymerase's processivity (the average length of extended
strand before dissociation from the template) rather than fidelity (the
number of changes in the product's sequence compared to that of template).
Anecdotally speaking, it appears that fidelity and processivity are often
REVERSELY related (i.e. Taq notorious [somewhat undeservingly] for its low
fidelity has higher processivity than some high-fidelity polymerases [such
as Pfu]). The adverse effect of high fidelity on processivity is easy to
understand if high fidelity is maintained via the 3'-5' exonuclease
activity, effectively antagonizing polymerization. 
Regards,
V. Svetlov

-- 
                                         Scott McMahan
                                         mcmahan at oncology.wisc.edu



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