>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
>
>vmtitov@aha.ru
>
>
>Dear Jean
Vladimir is right . The paranitroophenyl ester is an active
ester and will probably prefert to lactamize with the side chain of Arg
rather exist as an active ester.
Regards
Denis Scanlon
Auspep
AUSPEP PTY.LTD.
P.O.Box 806 Parkville
Vic. 3052 AUSTRALIA
Phn: + 613 9328 1211
Fax: +613 9326 8810
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