<x-charset X-UNKNOWN>A number of years ago, I tried to make a peptide containing a trimethyl
lysine, using the Boc method, with trifluoromethane sulfonic acid for
cleavage. I used Boc(epsilon Fmoc)lysine, and took off the Fmoc with
piperidine at the completion of the synthesis. I then used methyl iodide
for the methylation. It did go to the dimethyl stage, but no farther, no
matter what I did, and, I also got some methylation of a histidine in the
peptide and, because I had to use beta benzyl aspartic instead of cyclo-
hexyl, I got transesterification and ended up with beta methyl aspartic.
At that time, Boc dimethyl lysine was too expensive for us, so I gave up.
If your Fmoc dimethyl lysine won't dissolve in the FastMoc solvents, will
it dissolve in DMSO, which can be diluted with your solvents, or in
methylene chloride? You may have to take the peptide off the synthesizer
and do the one coupling manually, and then put it back. A good source of
information on methylated amino acids and the synthesis thereof is the
papers of Professor Leo Benoiton. They helped me a whole lot. Without
them, I wouldn't have gotten as far as I did.
Hope this helps.
Angela C. Murphy
On Tue, 15 May 2001, Isabelle Kelly wrote:
> Hi All,
> >
> > I have to synthesize a peptide containing a dimethyl-lysine. Since
> there are
> >
> > other Lys in the sequence, I know that I can use Fmoc-Lys(Ddiv) or some
> > other protected Lys derivatives that allow selective deprotection. Is
> > there anyone who has some information about how I can add a dimethyl or a
> > trimethyl on the deprotected lysine? Is the final product relatively
> > stable? Should I use some particular conditions for the HPLC purification ?
> >
> > I will REALLY appreciate any informations or reference that you have...
> >
> > I'm using a 433 peptide synthesizer from applied biosystem with the Fmoc
> > technology. Activation with HBTU/HOBT in DMFand DIEA.
> >
> > I bought a Fmoc-Lys(Me)2-OH from Bachem but it seems that it's not soluble
> > in these conditions...
> >
> > Thanks!
> > isabelle
>
>
>
>
> Isabelle Kelly MSc.
> Service Protéomique de l'Est du Québec,
> CHUQ Pavillon CHUL,
> 2705, Boul.Laurier,
> Ste-Foy, Québec,
> G1V 4G2
>
> Tel. 418-656-4141 ext. 7088
> Fax. 418-654-2159
> http://www.crchul.ulaval.ca/crchul/en/serv/Default.htm
>
***********************************************
Angela C. Murphy, Chemist
Lab. of Cell Biology, NHLBI, NIH
Detailed to: Lab. of Cell Biology, NCI, NIH
Building 37, Room 1B03
37 Convent Drive
Bethesda, MD 20892 USA
tel.: (301) 594-7420 or (301) 402-4428
fax: (301) 435-8188
email: acmurphy@helix.nih.gov
************************************************
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