Re: Peptide synthesis

Roger Murphy (murphy_r@licre.ludwig.edu.au)
Tue, 14 Jul 1998 09:18:39 +1000

At 03:56 PM 13-07-98 -0400, you wrote:
>Dear ABRF friends,
>
> We want to synthesize a 26-mer peptide for one of our users. The
>sequence of the peptide is as folows:
>
>NH2-GSSSGQLQSYICFC*LPAFEGRNC*ETH-COOH
>
>The investigator wants cysteines #14 & 23 to form the disulfide bond,
>while cys 12 to remain free. Any suggestions for synthesis strategy will
>be appreciated.
>Thanks in advance.
>
>Satya Yadav
>

Dear Satya,

The main sequence you have looks okay and should be straightforward to make
(at least by Fmoc methodology, which is where my expertise is) - perhaps
just keep a watchful eye on the YIC sequence during coupling. Regarding
the disulphide bridging, and this is again from the Fmoc viewpoint, I've
had success in using Trityl protecting groups for the Cys that I want
bridged and Acm or tBu for the one you want free. The Trt groups come off
in normal TFA workup and you can then oxidise (I like using 10%
DMSO/NH4HCO3) to form the disulphide bridge. You can then use TFMSA (to
remove tBu) or HgOAc2 (to remove Acm) and leave a free cysteine.

Hope this helps.

Roger

Roger Murphy, Ph.D.
Biological Production Facility
Ludwig Institute for Cancer Research
Austin & Repatriation Medical Centre
Studley Road,
Heidelberg, Vic. 3084
Australia.

Tel 61-3-94965463
Fax 61-3-94965436
Email murphy_r@licre.ludwig.edu.au