Dear Jennifer,
I would suggest to biotinylate the N-terminus of the peptide on the
synthesis resin, then cleave and deprotect the peptide. After purification,
the cyclization by disulfide bond forming between the 2 cysteines can be
done by one of the following ways:
- either use high dilution conditions to favour intramolecular cyclization
compared to peptide dimer formation
- or use Ekathiox resin from Sigma; with this reagent, intramolecular
cyclization is greatly favoured and one can work in concentrated solution.
This second method is clearly the better one, the high dilution conditions
generally give only low yields of cyclized product.
I hope this helps.
Gottfried Proess
Tel.: + 32 4 366 01 50 Fax : + 32 4 365 16 04
E-Mail: g.proess@eurogentec.com
Web-Site : http://www.eurogentec.com <==== visit it !
-----Message d'origine-----
De: Jennifer Woodman [SMTP:Jennifer_Woodman@dfci.harvard.edu]
Date: mardi 22 février 2000 20:45
À: Recipients of ABRF List
Objet: Peptides
Hello,
I was wondering if anyone out there could offer some advice on cyclic
peptides. We are currently working on a project that involves making a
cyclic peptide in which either the C or N terminus would be biotinylated.
My concerns are:
I believe I will need the free amine group to cyclize the peptide and
therefore will not have a free amine group to biotinlate.
In addition, both the C and N terminus have a Cysteine. We were thinking
that we might be able to cyclize the peptide by forming a disulfide bond
between the two ends. That way, we might be able to use the free amine to
biotinylate. If this is a possibility, how do we selectively have the
single peptide form a disulfide bond between its two ends rather than
having a chain formation.
I thank you for any advice,
Jen
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