phagemids vs plasmids

Carol Enderlin enderc at
Wed Jun 2 19:30:11 EST 1993

In article <1993Jun2.143717.14147 at> isbruck at writes:
>I recently received a cDNA clone that is inserted in a phagemid
>vector.  Can the phagemid be grown, amplified and isolated using
>the same methods used for plasmid isolation?  

Yes. Phagemid are generally plasmids that have a bit of f1 phage
DNA added to allow for the in vivo excision from lambda as well
as packaging of the plasmid as single-stranded DNA (for sequencing,
some of us prefer ssDNA for sequencing still) with the use of helper

Other than the addition of that phage DNA they are directly derived
from standard plasmids. Perhaps you could tell us which phagemid
and we could be more specific in answering your question or 
providing more information.

>I am currently
>isolating my plasmids using a CsCl/ultracentrifuging method but
>am not too sure if this will work for a phagemid.  Also,  are
>there any good references on phagemids?  the only thing I have
>read is the short blurb in the Maniatis volumes, but this does
>not have very much on the methods.

If you are using pBluescript phagemid, Stratagene has quite a bit
of information about their phagemids. However, most of the information
is relevant to in vivo excision, ssDNA preparation, and not how to
handle these as plasmids because (at least in my experience) they
behave like any other plasmid with an ampicillin resistance gene,
polylinker, blue/white cloning, etc.
>Richard Isbrucker			e-mail:  ISBRUCK at AC.DAL.CA
>Dalhousie University,			Tel:     (902) 494-2571
>Dept of Pharmacology

Carol Enderlin
enderc at

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