peptide synthesis

George A. Heavner gheavner at
Sun Jun 1 19:13:45 EST 1997

Rob wrote:
> Hi
> Does anyone know of a way to incorporate a label (e.g. biotin or
> fluorescent tag) into a peptide during solid-phase synthesis? - I suppose
> I'm really asking if labelled protected amino acids are commercially
> available...
> Thanks in advance
> Rob

Incorporation of biotin or a fluorescent label into a peptide via solid
phase synthesis is actually quite simple.  It can be done using either
BOC or FMOC protocols.  For example, using FMOC chemistry, couple
BOC-Lys(FMOC) or Ac-Lys(FMOC) as the final N-terminal amino acid. 
Deprotect and couple biotin to the free amino group.  It can be coupled
directly using DCC/HOBt in NMP/methylene chloride or via its OSu ester. 
I prefer the second route because of better solubility.  Similarly
FMOC-Lys(BOC) can be used with a BOC protocol.  Biotin and many
fluorescent labels are stable to deprotection and cleavage conditions. 
Lysine works well for incorporation since it provides a 4-carbon
spacer.  Other spacers work as well.  I do not suggest direct coupling
to the alpha amino group because of possible steric interactions.  If
you want you can incorporate BOC-Lys(FMOC) as the C-terminal amino acid
(or any other amino acid) and put the label in that position.  

I've made thousands of labeled peptides using these protocols on an ABI
431, ABI 433 or 96 at a time on an ACT multiple peptide synthesizer. 
Contact me if you have any difficulties.

George A. Heavner
Senior Director, Peptide R&D
Centocor, Inc.

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