Hi all,
I'm trying to modify COOH group of peptides using the water soluble
carbodiimide EDC and the amine glycyl ethyl ester. I have succesfully
done this for a number of peptides. However, mass-analysis of
the modified peptides occasionally show peculiar adducts (i think that they
are on tyrosine residues). I suspect that these adducts are products of a side
reaction of EDC and N-acylurea. Anyway, to overcome this problem,
i want to try to modify the carboxyl groups in an organic solvent
(eg acetonitrile or tetrahydrofuran) and use the dicyclohexylcarbodiimide
(DCCD) instead of the watersoluble carbodiimide EDC. However, one problem
i'm facing with this reaction is that i can't find a suitable amine that is
soluble in an organic solvent, (and i don't want to work with analine or
other extreme toxic amines).
My question; has anyone got any experience with the dicyclohexylcarbodiimide
chemistry (on peptides) and what would be the best amine that i can use to
couple it to a carboxyl group using DCCD.
Thanks in advance.
Martijn Pinkse
Biomolecular mass-spectrometry and protein structure research
University of Amsterdam
mwhp@dds.nl
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