Long PCR products

[Dr. Duncan Clark]

In article <F3AK22.Msz.F at zoo.utoronto.ca>, Kowthar Salim
<kowthar at zoo.utoronto.ca> writes
>I am currently trying to amplify a region in a genomic DNA that is about 
>3kb long.

What type of genomic, bacterial, human, plant etc.?

3kb of bacterial should amplify with Taq. 3kb of human genomic will
present more of a problem and may require the use of a mix of Taq and
proof-reading pol. What are your exact PCR conditions i.e amount of
enzyme, no. cycles, amount of template etc.

>
>I have tried to increase the extension time (3 minutes) during the PCR 
>reaction.  Unfortunately, this has not yielded any PCR products.

3mins is fine for Taq or a pol. mix

>
>I was wondering if anyone has any suggestions or if any references can be 
>recommended.

Check out papers by Wayne Barnes in PNAS.

Duncan

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

Duncan Clark
DNAmp Ltd.
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