DMSO addition to sequencing

Alexander Alexander
Sun Jul 20 14:15:22 EST 1997

In article <5qopvn$ofb at net.bio.net>, Kari Ohlsen,
kohlsen at sunstroke.sdsu.edu wrote:

> I was wondering what other people have experienced using DMSO to clean
> up dirty sequences.  We have noticed that adding DMSO severely decreases
> the signal, and only occasionally actulally helps the data. We are
> wondering if this is normal.  Is there a specific purity/manufacturer of
> DMSO which is recommended for this purpose?  Our DMSO is over 2 years
> old, could this be a problem?

Exactly. Buy a new bottle, e.g. from Sigma, aliquot into 0.5 ml tubes and
store at -20 C. Thaw one, use and discard the rest. Actually, I collect 
that show no ladder <without> 10% DMSO ( I already have quite a few),
because they are very GC-rich. Addition of DMSO to every reaction may have
no effect in most cases, but with GC-rich sequences it saves the bacon!
So much DMSO, however, requires annealing temperature step to be shifted
by 5 C lower than used without it for a given primer.

Best regards,

Alexander Kraev, PhD
Swiss Federal Institute of Technology (ETH)
kraev at bc.biol.ethz.ch

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