Urgent help for plasmid purification

rebecca rebsilver at usa.net
Tue Mar 3 07:40:50 EST 1998


Hi,

The advice from Richard is pretty good if this is a contaminant.
But you probably shouldn't use the same DNA stock. The one time we had
this, we decided it was some sort of crazy 'wild' plasmid from the lab
bench or something. We went back to the original glycerol stocks and
re-preped and then it went away. If you don't have that option, maybe try
gel purifying your plasmid. We had a set of competent cells with a whole
extra mini-plasmid as well, once upon a time.....

In the case that this is a fragment that only shows up after digestion: I
have heard of Clontech plasmids that had MCS sites marked on their maps
that were not actually unique.  You might want to check that (Sometimes
they know and you just need to ask. The guy I know ran the controls then
called and asked, and they said yeah we know, sorry. This was a while ago,
so I don't want to be too hard on them.)

Cheers,
Reb

Todd Serulneck wrote:

> Hi! Guys:
>
> Help need for plasmid DNA purification.
>
> I am purifying plasmid DNA using Promega miniprepa DNA Purification
> System
> from Novablue cell transformated by Clontech pEGFP-N1 containing the
> insert. Some strange things happened, I really got the plasmid with
> insert, but allways companied by
> a 580 bp DNA band. Since the plasmid DNA is to be used for transfection,
> so I got to figure out  what  it is.
> Does anybody have experience about this?
>
> Please help!
>
>








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