ez001427 at dale.ucdavis.edu ez001427 at dale.ucdavis.edu
Fri Aug 26 19:23:12 EST 1994

Dear Helpful Netters,

	Thanks for the quick and thoughtful responses to the RNA removal 
question.  I thought I'd post the resulting suggestions in summary form 
here to help anyone with similar problems.

	By far the most highly recommended process was PEG precipitation 
in one incarnation or other.  I'll be trying this.
	One person suggested alkaline hydrolysis of the RNA, which should 
leave the DNA intact.  I may give this a go, but as my DNA bases are 
modified by methylation, I'm concerned that they may be less chemically 
stable and tend to be released under the suggested hot/alk conditions.  
An excellent idea however, for next time when I purify the DNA _FIRST!_, 
and then radiolable it with methyl groups.  
	I have also been told about Biorad's A-50 resin, a convenient 
size-chromatography resin for column chromatography.  This would be 
useful either as a pre-labeling procedure to remove RNA or as a 
post-label treatment tor remove both RNA and unincorporated label.

	Finally, it occurred to me that if the labeled RNA goes through 
the spun-column filters that I want to use in my assay, I could use them 
or their larger cousins to spin out the RNA, leaving the DNA substrate I 
want in the retained volume.  This might be an easy way to go about it, too.

	Again my thanks to all who helped.

Marc Goldstein
magoldstein at ucdavis.edu

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