RNase protections assays. Too much salt?

Pamela Norton pnorton at lac.jci.tju.edu
Wed Mar 20 17:43:12 EST 1996

In article <4in49v$7di at reeve.research.aa.wl.com>, Angela Hofstra
<Hofstra at aa.wl.com> wrote:
> Lately we've been having trouble with the last precipitation step in our 
> RNase protection assays. We follow the procedure essentially as outlined 
> in "Current Protocols in Molecular Biology".  After precipitating in 
> ethanol we get lots of white precipitate, which I suspect is largely 
> salt.  When we dissolve the pellet in loading buffer and load it on a 
> vertical gel the sample rises.  


   I must confess that I have never seen samples float from high salt, but
I would imagine that this is possible. I have seen them float because the
ethanol has not been removed in entirety. 

   Try washing the pellet with 70% ethanol, then re-centrifuge and dry.
The extra step is a nuisance but it should solve your problem. 

   Good luck,

      Pam Norton

Pamela A. Norton, Ph.D.          Assistant Professor of Medicine
Thomas Jefferson University
Philadelphia, PA 19107           p_norton at lac.jci.tju.edu

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