Date: Thu, 16 Jan 1997 12:09:00 -0600
Message-Id: <v01530503af051cdbf0d3@[128.252.197.88]>
To: abrfhyp@cco.caltech.edu
From: rskubish@pharmdec.wustl.edu (Richard Skubish)
Subject: PepSyn-disulfide exchange
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>Date: Wed, 10 Jul 1996 10:35:08 -0700
>Old-To: abrf@aecom.yu.edu
>From: jack.moore@ualberta.ca (Jack Moore)
>Subject: PepSyn-disulfide exchange
>To: Recipients of ABRF List <abrf@aecom.yu.edu>
>Sender: Association of Biomolecular Resource Facilities
><abrf-request@aecom.yu.edu>
>Precedence: bulk
>
>I am working on a synthetic peptide that seems to be exchanging disulfides and
>would appreciate any suggestions on how to minimize this problem. The sequence
>is CYIQNCPLGGKR. Both terminals are free and the two cys residues form a
>disulfide. After purification, oxidation and another purification I have
>my desired product at a purity level of greater than 95%. The problem is
>that I can't stop the peptide from forming new oxidation products. This
>occurs after a couple of days as a lyophilized powder. It happens on both
>the benchtop and the freeze drier. I'm sure that the desired peptide has
>been made as I've characterized it to death so it's not just a case of the
>reduced peptide forming random oxidation products. The exchange happens as
>a TFA salt, an HCl salt and also seems to be happening as an acetate salt.
>It is most stable as a dilute solution (~0.1 mg/mL) but unfortunately the
>end user can't have it like this.
> Does anybody have any ideas?
>
>Thanks - Jack Moore
>
>P.S. Two other peptides, one minus the arg and the other minus the lys and
>the arg are also doing the same thing.
>
Richard Skubish
rskubish@pharmdec.wustl.edu
314-362-0283
Washington University Medical School
Box 8103 - PNACL
660 S. Euclid
St. Louis, MO 63110