DMSO vs. raising annealing temp. in PCR

[Jerry Kropp]

> : I am trying to amplify a fragment of about 100 bp but 
> : am getting a smear of products with only little of the desired one.
> : I am not using too many cycles and have raised the annealing
> : temperature to its highest limit.
> 

Timo,
DMSO may help at 5-10%. Or other optimization tricks, like titrating Mg.
If that doesn't cut it, grit your teeth design a new primer pair.
I've found the "internal stability" parameter in the Oligo primer analysis
application to be very useful for avoiding promiscuous primers.
Good luck,
Jerry

-- 
"no brains...no headache!"