Large PCR products? from what source.

Mike Morris mike at
Fri Feb 4 07:00:17 EST 1994

 I am surprised to see 2.5 kb appear in this discussion. Working from 
human genomic DNA, we regard above 3 kb as starting to get difficult;
up to 5 kb, you can (almost) always do it with "standard" PCR (ie
AmpliTaq). Just optimize _everything_ - "touchdown" PCR for maximum
yield, and titrate Mg and primer concentrations. Try 5 or 10% DMSO -
if your primers work with it, leave it in. We increase denaturation
to about 1 min at 92°C, and extension to 3-5 min. 
Michael Morris PhD            
Division of Medical Genetics       tel (Switzerland) (22) 702.56.94
CMU, University of Geneva          fax (Switzerland) (22) 702.57.06
Geneva, Switzerland                email mike at                  

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