Date: Thu, 16 Jan 1997 12:38:52 -0600
Message-Id: <v01530518af0523df96f8@[128.252.197.88]>
To: abrfhyp@cco.caltech.edu
From: rskubish@pharmdec.wustl.edu (Richard Skubish)
Subject: PepSyn: Cyclized
>Date: Mon, 1 Jul 96 14:03:21 CDT
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>From: jsmcmur@utmdacc.mda.uth.tmc.edu (John McMurray)
>Subject: PepSyn: Cyclized
>To: Recipients of ABRF List <abrf@aecom.yu.edu>
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><abrf-request@aecom.yu.edu>
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>
>Lisa,
>
>Concerning the synthesis of
>
>cyclo[C K G D K G D K G D]:
>
>With the N-terminal Cys, the on-resin cyclization procedures mentioned by
>Ron Haaseth and Dick Noble are probably your best bet. Two things to watch
>out for are racemization of the C-terminal Asp and oligomerization of the
>peptide to give dimers, trimers, etc. Using on-resin cyclization of
>decapeptides we noticed anywhere from undetectable to 30% racemization and
>also got varying amounts of oligomer formation. As is the case with all of
>peptide synthesis, these side reactions depend on the sequence, support,
>coupling reagent, etc. Keep the resin loading as low as possible. We got
>our best results using DIPCDI/HOBt in DMF/DCM in the cyclization step.
>
>We also found that you can remove the side products with RP-HPLC without
>much trouble. In our cases, the cyclic peptide diastereomers were
>separated best using 0.01M NH4OAc/ACN gradients as opposed to 0.1% TFA/ACN
>systems.
>
>We wrote our stuff up in Tetrahedron Letters 32:7679-7682, 1991, and
>Peptide Research, 7:195-205, 1994.
>
>I wil be curious to know how your synthesis turns out. Best of Luck!
>
>John
>
>John S. McMurray, Ph.D.
>University of Texas M.D. Anderson Cancer Center
>Dept. of Neuro-Oncology, Box 316
>1515 Holcombe Blvd.
>Houston, TX 77030
>Phone: 713-794-1574
>Fax: 713-794-4999
>jsmcmur@utmdacc.uth.tmc.edu
>
Richard Skubish
rskubish@pharmdec.wustl.edu
314-362-0283
Washington University Medical School
Box 8103 - PNACL
660 S. Euclid
St. Louis, MO 63110