Phage display systems

Pascal Mertens Pascal.Mertens at fundp.ac.be
Wed Oct 22 07:25:53 EST 1997


In article (Dans l'article) <344CD704.56EA at chugaibio.com>,
dspinella at chugaibio.com, @chugaibio.com wrote (écrivait) :

> Keith Jolley writes:
> > We are considering using a phage display system .... Does anyone's
> > experience bear this out?
> > I would also be interested in hearing of experiences with
> > other similar systems.
> > 
> > Thank you,
> > Keith Jolley
> 
> 
> Keith:
> 
> There are two considerations here.  First off, NEB is correct: their
> dodecamer library affords a "sliding window" effect ...

> The alternative consideration however is that many antibody epitopes are
> in fact 6-7 residues long, and are simple linear (i.e.
> non-discontinuous) sequences.  Hence, for the longer displayed peptides,
> once you isolate a binding phage and infer the amino acid sequence of
> the displayed peptide, you still won't know immediately which of the
> overlapping peptides constitutes the epitope...

> our solution is to screen ALL
> our libraries simultaneously and use the data from the shortest
> isolate.  

The solution also comes when you have a consensus sequence present in all
(or most) of your binding peptides. You can have 10 different 12mer
peptides with a strict 4 or 5 mer consensus sequence (not necessarily at
the same place in the 12mer, so you need to "slide" the peptides between
them.
In some cases there are no consensus sequences, and some or all the
binding peptides are not similar to the epitope but are called mimotopes.
Mimotopes are structures (here, peptides) that bind the same Ab that your
epitope because the important charasteristics for binding are present at
the right places (you can have a peptide that is a mimotope of a
non-peptidic epitope!).
So remember that a binding peptide does not necessarily give you the
sequence of your epitope (I mean the epitope on your Ag).

Pascal Mertens

-- 
Pascal Mertens
Laboratoire d'Immunologie et Microbiologie
URBM-FUNDP
61 Rue de Bruxelles
5000 Namur, BELGIUM
Phone: 32 81 724438
Fax: 32 81 724420



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