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Subject: RE: question about peptide synthesis
Date: Tue, 15 May 2001 17:15:21 -0400
Message-ID: <NEBBJOMIGLGPCBGHCMKNEEMCCCAA.michael_shiue@pbcpeptide.com>
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Dear Wei-Zhen:
We just happened to synthesize recently a peptide with the exact same
sequence plus few more amino acids at N-terminus of yours. There is no
problem and the yield is pretty good. This is our coupling condition: Fmoc
chemistry, three equivalents of Fmoc-aa, coupling reagents -
HBTU/DIEA/DMF/30minutes. You may try this condition. It should work well.
Good luck.
Michael G. Shiue
Princeton BioMolecules Corporation
2260 Cabot Blvd. West, Suite 4
Langhorne, PA 19047 USA
215-891-0415 (phone)
215-891-0419 (fax)
==================================
-----Original Message-----
From: Association of Biomolecular Resource Facilities
[mailto:abrf-request@aecom.yu.edu]On Behalf Of Auspep Staffmember
Sent: Monday, May 14, 2001 10:57 PM
To: Recipients of ABRF List
Subject: Re: question about peptide synthesis
Dear Wei-Zhen
There are number of things to try when a synthesis "shuts down". One is
to try pre washing the resin with DCM/TFE (70/30) several times to change
the swelling properties of the resin. Other coupling reagents you could try
are HATU/DIPEA ( which works well in cases like this ) or HOOBt/DCC (
activated in the same way as an HOBt ester and is best left overnight).
Also try adding more DCM to the coupling solution until the resin is
floating on the solvent and is swollen. If you simply cannot drive the
coupling to completion then acetylate and go on, or treat with Z-NHS ester
with an eq of base and then go on . The acetylated products should elute
earlier in RP HPLC or the Z-peptides will elute later.
Hope some of this helps
Denis Scanlon
Auspep Pty Ltd
At 06:50 AM 15/05/01 , Wei-zhen Shen wrote:
>I have a question ragarding the peptide synthesis problem. One of my
investigator wants a 14 mer peptide (NH2-NTWTTCQSIAFPSK-COOH). When I tried
first time, the synthesis failed. Now second time the peptide has been
synthesized upto cys (CQSIAFPSK). The synthesis looks OK by checking the
coupling of cys but the coupling of next Thr, is still showing ninhydrin
positive color. I am using the Fmoc chemistry and tried using DIC as well
DIEA with HBTU. Any suggestion or tips will be helpful.
>
>Wei-Zhen
>
Auspep Pty Ltd
115 Ireland St
West Melbourne
Australia 3003
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