Sometimes it is possible to take advantage of the different pKa's of the N
terminal amine and the amine on the lysine side chain. By coupling an NHS
activated bifunctional cross-linker to the peptide under specific reaction
conditions you can specifically target one or other of the amines. An HPLC
purification step after coupling the cross-linker will allow you to remove
the small amount of peptide that was activated at the amino terminus.
Karen De Jongh
> ----------
> From: Thomas Andersen
> Sent: Friday, November 19, 1999 10:46 AM
> To: Recipients of ABRF List
> Subject: PepSyn
>
> I need to synthesize a peptide and then couple it to a macromolecule,
> preferably through an amino group on my synthetic peptide. But I need to
> keep the N-terminus of the synthetic peptide free, as it is essential for
> activity. What is the best way to protect the a-amino group until I am
> ready to make it available?
>
> a. Will keeping the FMOC on it work? Can I do that and couple through
> some distal Lys amino groups with N-hydroxysuccinimide activated
> macromolecule, and then deprotect the peptide?
>
> b. Is there some other protection strategy that is good for this?
>
> c.) Of course I can insert a Cys and couple through -SH, but I'd rather
> not if I don't need to.
>
> d.) And I could get elaborate and engineer a site for proteolytic
> cleavage which would leave my desired N-terminus, but surely this won't be
> necessary?
>
> I'd appreciate any thoughts.
>
> Tom Andersen
>
>
> ó----------------------
> Thomas T. Andersen, Ph.D.
> Protein Chemistry Core Facility
> Albany Medical College
> Albany, NY 12208
> 518 262-5368
> 518 262-5689 fax
> anderst@mail.amc.edu
>
>
>