Date: Wed, 22 Jan 1997 09:32:57 -0600
Message-Id: <v01530501af0ce13e0581@[128.252.197.88]>
To: abrfhyp@cco.caltech.edu
From: rskubish@pharmdec.wustl.edu (Richard Skubish)
Subject: cyclization of dissulfide peptide
>Comments: Authenticated sender is <titov@ibch.siobc.ras.ru>
>From: "Vladimir Titov" <titov@ibch.siobc.ras.ru>
>Organization: Shemyakin-Ovchinnikov Institute of bioorgan
>Old-To: abrf@aecom.yu.edu
>Date: Fri, 6 Dec 1996 15:42:44 +0300
>Mime-Version: 1.0
>Subject: Re: cyclization of dissulfide peptide
>Priority: normal
>To: Recipients of ABRF List <abrf@aecom.yu.edu>
>Sender: Association of Biomolecular Resource Facilities
><abrf-request@aecom.yu.edu>
>Precedence: bulk
>
>> Dear All,
>>
>> We have recently been requested to make and cyclize the following
>> peptide PCSAHDHRCLQKY-amide. We have tried both the DMSO and the
>> ferricyanide procedures described by ABI which have worked well with other
>> sequences. With this peptide we get approximately 5% cyclization and
>> nothing that we have tried, including acylation of the N-terminal amino
>> group before deblocking and cleaving has improved the yield. The peptide
>> is being synthesized via the F-moc method. Incidentally the crude
>> material shows 99% the correct molecular ion for the structure containing
>> a completely deblocked peptide with (probably) two cysteines. I am not
>> really positive that the two cys's are reduced but reducing them before
>> cyclization has no imporved the situation.
>>
>> Does anyone have information that might be of help here?
>>
>> Frances Finn
>>
>
>Test if your SH-groups are free by Ellman. If there is anything to
>oxidize, try air oxidation at slightly basic pH. It may take some days.
>Monitor the reaction by Ellman test. Be sure to remove all reducing
>scavengers.
>
>Hope this helps
>
>
>Vladimir Titov
>
>MailTo:titov@ibch.siobc.ras.ru
>http://titov.siobc.ras.ru
>
>Visit Vladimir's peptide page at:
>http://titov.siobc.ras.ru/peptide
>
Richard Skubish
rskubish@pharmdec.wustl.edu
314-362-0283
Washington University Medical School
Box 8103 - PNACL
660 S. Euclid
St. Louis, MO 63110