RNA REMOVAL: Help!

[ez001427 at dale.ucdavis.edu]

Dear Netters,

	I could use some help in removing trace quantities of RNA from a 
pBluescript plasmid prep that I have.  I made a very large (15 mg) prep 
by traditional means, and used a combination of RNASE A and RNASE T1 to 
chew up the RNA.  I thought that that would be sufficient, but it turns 
out that the small amount of tiny (runs below 200 bp vs. dsDNA ladder) 
RNA remaining is a problem.  So I used a CsCl2 gradient, which removed 
90 % the RNA, but still there is enough to cause a problem. I would 
appreciate any suggestions for chemically gentle (non-DNA-damaging) 
methods to remove the trace RNA contamination that remains.
	One suggestion I have had is to run a gel filtration column.  If 
any of you have experience with such, and could recommend the best media, 
column conditions, etc.. I would be very grateful.  

	Thank you in advance for your help, either as a followup post 
here or as email to the address below.

Marc Goldstein
Section of Plant Biology
U. C. Davis
magoldstein at ucdavis.edu