Plasmid Digestion Problem

[Haydee Lopez]

Dear all,
After I extract my plasmid I usually run a sample to be sure the plasmid it=
s
fine and once there I=92m sure that my plasmid its fine I continue with the
next step and here comes my problem; I tried to digest the vector
pPICZalphaA + my insert with different enzymes and I obtain only a smeared
band. I use as a control the same vector without the insert and works
perfectly, the buffer, enzyme even the extraction method are the same.   I
incubate both plasmids with only the buffer without enzyme and the result
was the same. I think that probably was contamination with DNases but only
one plasmid has been affected, so I=92m not so sure. I tried with others mi=
ni
preps and nothing changes. After the extraction the plasmid looks great in
agarose gel. The strain there I=92m using is TOP10. If anyone has an idea o=
f
what=92s happening I really appreciate your help.
Thank you and best regards.
HL