On 20/12/1999, Lefebvre, Jean wrote:
> Hello,
> someone asked me a paranitrophenol labeled dipeptide (Z-Phe-Arg-pNP).
> Could someone help me with a protocol or a commercial source...
A difficult task indeed!
I would firstly try to get Z-Phe-Arg-OH from a Z-Phe active ester
(ONSu, ONp...) and free arginine, than react the dipeptide with
DCC/HONp and try to isolate the target product (most probably, quite a
few!) from the reaction mixture. An alternative is a mixed anhydride
procedure, which I believe would also lead mostly to a cyclization
product but can also produce at least a little bit of ester. Maybe,
there is also an enzymatic way. Under DCC/HONp or MA reaction,
C-terminal Arg in your dipeptide may undergo racemization.
Hope this helps
Vladimir Titov
Bokiron Ltd., Moscow, Russia
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