HELP! Genomic DNA not cutting!

Ron Caspi rcaspi at
Fri May 26 16:43:37 EST 1995

In article <S.Rowland-1505952146120001 at>, 
S.Rowland at says...
>In article <1995May11.191903.7840 at mcrcr6>, 
galinm01 at wrote
>> Hello!
>> Seeking suggestions on "how to" "clean-up"  genomic DNA that
>> refuses to digest with restriction enzymes.

... how to fix this problem by dialysis.

Well, I have had similar problem with a specific strain of bacteria, and in that 
case, dialysis did NOT help! I beleieve that I had a problem with 
polysaccharides or carbohydrates that would not separate even during 
dialysis. What I found to work great, are the new columns of Qiagen,which 
remove polysaccharides. What used to take 300 ml of culture and 15(!) 
phenol-chloroform extractions, followed by dialysis, is now accomplished with 
5 ml in less than one day (not including resuspension of DNA) and the DNA is 
I do not own Qiagen (unfortunately) or associated with them by any means.

Hope it helps

Ron Caspi
Scripps Institution of Oceanography
La Jolla  CA  92093-0202

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