Date: Thu, 16 Jan 1997 12:18:37 -0600
Message-Id: <v01530515af051f1b782b@[128.252.197.88]>
To: abrfhyp@cco.caltech.edu
From: rskubish@pharmdec.wustl.edu (Richard Skubish)
Subject: peptide synthesis -18 mass
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>From: lcp2@mole.bio.cam.ac.uk (Len Packman)
>Subject: Re: peptide synthesis -18 mass
>Date: Sun, 25 Aug 1996 11:00:07 +0100
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>Peggy,
>
>If you have purified and kept the peptide in acidic conditions, it is
>likely that there has been no significant conversion of the -18Da peptide
>(almost definitely aspartimide) back to the asp or isoasp form. You could
>try ion exchange or (my preference) hplc at pH6 (ammonium acetate) to
>resolve out the -18Da peak. The aspartimide peak seems stable for several
>hours at this pH, but opens up easily at higher values (e.g. pH8). You can
>first check the stability by incubating a small amount of sample at pH3,
>pH6 and pH8 and then running analytical hplc to see how the relationship
>between the two peaks changes. Once you are satisified that the peaks stay
>the same at pH6 for several hours (e.g. overnight), you can embark on a
>purification of the higher mass product.
>
>If you decide to remake, use Hmb-Gly
>
>Len
>
>******************************************************
>Dr Len C. Packman
>Assistant Director of Research
>Protein and Nucleic Acid Chemistry Facility
>Department of Biochemistry, Tennis Court Road, Cambridge, CB2 1QW, UK
>Tel: +44 (1223) 333639 (including answerphone)
>FAX: +44 (1223) 333345
>e-mail: lcp2@mole.bio.cam.ac.uk
>Visit my WWW page at http://www.bio.cam.ac.uk/proj/adr/PNAC/pnac.html
>
Richard Skubish
rskubish@pharmdec.wustl.edu
314-362-0283
Washington University Medical School
Box 8103 - PNACL
660 S. Euclid
St. Louis, MO 63110