From: Cole, James L <jim_cole@merck.com>
  To  : 'Borries Demeler' <demeler@bioc09.v19.uthscsa.edu>
  Date: Thu, 14 Jun 2001 15:28:06 -0400

RE: RNAse contamination in AUC CP's

Borries:
We  have been doing some tests for just this problem with rna oligos. After
the usual cleaning and storage we  sprayed our  centerpieces (carbon-epon)
with an alkaline cleaning solution called RNAzap  (Ambion) , washed
extensively with RNase-free water and then dried. Nonetheless, we  observed
some RNase activity over several days in some of the  equilibrium runs with
RNA oligos. The solution has been to add recombinant RNase inhibitor to the
buffers. This is a small protein inhibitor that has a very high affinity for
RNase A. You need to add very little, so it does not contribute appreciably
to the absorbance/interference signals.  The samples are now stable for
several days at 20 degrees.  This stuff is available from ambion, promega,
and probably other companies as well. You need to have DTT present for it to
work, but I think that someone is also selling a version that does not
require a reductant.
Jim Cole

-----Original Message-----
From: Borries Demeler [demeler@bioc09.v19.uthscsa.edu]">mailto:demeler@bioc09.v19.uthscsa.edu]
Sent: Thursday, June 14, 2001 3:08 PM
To: rasmb@alpha.bbri.org
Subject: RNAse contamination in AUC CP's


Hi,

I would like to know if someone has any experience running RNA in an
AUC over longer time periods in equil. expts. and what measures one can 
take to eliminate RNAse contamination in the CP's.

Any suggestions?

Thanks, -Borries