At 01:00 PM 02/08/2000 -0500, divakaramenon venugopal wrote:
>Hello all,
> I have been trying to attach a mono protected diamine
>{Trt-NH-(CH2)4-NH2.AcOH} to the side chain (COOH) of a Glu (23 AA long
>peptide attached to the resin) by standard Fmoc coupling protocols. I
>tried HOBT / HBTU and HOAT / HATU protocols using 10 fold excess of the
>mono protected diamine for varying amounts of time. The reaction proceeded
>to a certain extent, since I could see the adduct in the MALDI spectrum.
>However, the required adduct was present only up to a maximum of 8 % as
>evidenced by HPLC and MALDI results.
>
>Now, my questions are
>
>1. Is there anybody who tried to do this reverse order coupling (i.e. COOH
>on the resin and amine in the solution using FMOC chemistry) and what are
>the findings ?
>2. What is the best source of information available on this particular
>subject (I did a reasonable search in the literature)
>
>thank you all for the attention
>
>D. Venugopal
>MicroChemistry
>LFKRI/NYBC
>New York 10021
>
>
> I asume your peptide on the resine are still fully protected except
that of the carboxy group of glutamic acid. I think if you first make the
actived ester with DCC and HOSu in DMF over night, than wash throughly with
DMF,DCM and DMF. you might have to repreat this prcedure one or a couple
more time. Now you can react the actived ester with your neutralized
diamine in DMF at rome tempture. good luck.
Alfred Chung
alfred chung
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