Wolfgang Schechinger novalidaddress at
Tue Apr 11 18:33:42 EST 2006


There is a (at least theoretical) possibility that you get modified
amino groups when you treat your DNA with aldehydes / ketones by
formining imines. This reaction is reversible however. Most restriction
enzyme won't be bothered by methylated DNA, but it's likely that some
will be by similar modifications as they need some space. I remember an
advertising for a DNA concentration kit (discussed in
bionet.molbio.methds-reagnts about 1 year ago) claiming to maintain DNA
cleavable by a certain restriction enzyme (I forgot which) where EtOH
precipitation rendered teh DNA undigestable.

As ethanol becomes oxidized quicker if you expose it to air (oxygen),
at RT and light (maybe even direct sunlight?) you will increase amount
of impurities present (acetic aldehyde) which might react with your DNA
and modify it. Johannes' reply with the acetone wash goes into the same
Keeping the EtOH in the -20 (which I was tought to do many years ago,
but noone could explain to me why) at least would keep the Ethanol on
the safe side. Of course, the same would be necessary with the iPropOH.

When I find the time, I'll do some more systematic checks and post the


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