Cutting Qiagen miniprebs??

Tracy Aquilla aquilla at
Tue Apr 2 10:39:09 EST 1996

In Article <315D9F6C.24D9 at>, Richard Daines
<rdaines at> wrote:
>Bjoern Voldborg wrote:
>> Hello out there,
>> I am having serious problems cutting plasmids (pBlueskript) prepared with the
Qiagen minipreb kit. The plasmid comes from a Xblue MRF' strain 
>and contains an i
>> Is there anybody that has experienced the same thing, why is it happening,
and how do I solve it.

>It may be important to know what strain of host E. coli you are using.  
>While Qiagen preps. work extremely well with DH5alpha, other may not.

In this case, I doubt the problem is with the choice of host strain. While
it's true that these preps work better for some strains than others, the XLI
Blue MRF' strain is one that works consistently well with the Quiagen prep,
in my personal experience. I think the manual lists which strains give
consistent results and XLI is one of them (as is DH5). It is difficult to
suggest a solution to your problem without more details. Which enzymes have
you tried? Can you get at least partial digestion with ANY REs? How many
bands does the uncut plasmid produce on the gel? If the plasmid is
permanently denatured (i.e too long in contact with P2 buffer) it will
migrate faster than expected and will not cut. Good luck.

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