Problems isolating plasmids from E.coli JM110

Trond Erik Vee Aune teva at
Sat Mar 3 12:36:17 EST 2001


I am having problems with isolating plasmids from the dam negative
E.coli strain JM110. I have read that it has a endonuclease that cleaves
double stranded DNA and that this is the reason for the problems. Still
I manage to isolate some of my plasmids, but not the others. I have
tried SV Wizard miniprep (column) and ordinary isopropanol-method. After
isolation and digestion with restriction enzymes I can see no bands on
the gel.

All the plasmids are low-copy, but the ones I have trouble with have a
copy-up mutation that makes the copy number about 10 times higher than
the ones I have managed to isolate from.

Any help would be appreciated!

Trond Erik Vee Aune

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