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DNA contamination of RNA preparations

Fri Aug 6 21:05:10 EST 1993

> From:	IN%"<@CGNET.COM:BSS027 at uk.AC.BANGOR>"  "BSS027"     6-AUG-1993 22:53
> .. Has anyone else experienced this  problem and can suggest methods of 
> reliably getting rid of all of the DNA from the mRNA prep.  We are currently 
> using a guanidinium thiocyanate extraction procedure for total RNA followed 
> by purification on an oligo dT colum. We have tried treating with DNase but 
> the RNA degrades as well!
> Dr. Sue Assinder

Here's how one easy way to get rid of residual RNAse in your DNAse prep (from
Sambrook et al., Molec. Cloning, 1989):

1. Prepare a 1 mg/ml DNAseI stock in 0.1 M iodoacetic acid-0.15 M sodium
acetate (pH 5.2)

2. Incubate the solution for 45 min in a 55 degrees Celsius bath and
chill on ice. Then add 1 M calcium chloride to a final concentration of
5 mM. Aliquot and store at -20 degrees.

R. Scott
Plant Pathology Division
International Rice Research Institute
POB 933, 1099 Manila, Philippines
e-mail: rscott at irri.cgnet.com 

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