Desalting of Plasmid DNA after Cesium Preps

Arnoud van Vliet arnoud at vanvliet.u-net.com
Tue Jul 7 17:34:17 EST 1998


Hi Obaid Khan,

when you precipitate your samples, do you freeze them or put them on ice?
with cesium salts that causes salt precipitation. Just do an ethanol ppt
without adding salt. Should work fine, as long as your centrifugation speed
is high enough (>10,000 x g)

hope this helps
Arnoud

Obaid Yusuf Khan <9321531k at clinmed.gla.ac.uk> wrote in message
<6nt0me$gof at singer.cent.gla.ac.uk>...
>Hi,
>
>Does anyone know about a method to remove Cesium from the plasmid DNA
>after a Cesium Chloride-Ethidium Bromide density centrifugation. I have
been
>using dialysis for desalting but its time comsuming. I have also used
Centricon
>columns, but they can only take upto 500 mcg of DNA and you usually get
over a
>mg of DNA in cesium preps. I have also used ethanol ppt method, but I tend
to
>loose a lot of DNA this way.
>
>I will appreciate any help/tips for desalting the plasmid DNA, which
consumes
>less time and does not damage the supercoiled structure of DNA.
>
>Thanks very much
>
>Obaid Khan
>





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