PEG Plasmid Maxiprep Problem

Warren Gallin wgallin at
Wed Jul 2 18:16:51 EST 1997

I have done several maxipreps from 250 ml cultures grown in terrific broth,
according the the method in Current Protocols in Molecular Biology. 
Everything went well, good yield, nice clean DNA, except for two things.  1)
After dissolving the PEG pellet and precipitating with EtOH, I got a large,
flocculent, white precipitate instead of nice stringy DNA and 2) the stuff,
which redissolves quite well, appears to inhibit restriction enzymes, so I
can't cut the DNA.
    Does anyone know what this stuff is (I haven't seen it in the past while
doing the same protocol) and more important, how can I separate my plasmid
DNA from this stuff.


Warren Gallin
Department of Biological Sciences
University of Alberta
Edmonton,  Alberta     T6G 2E9
wgallin at

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