There have been a couple of posters mentioning this problem, but I'm not sure if
anything has been published yet. Steve Kent had one at the last European Peptide
Symposium. His results showed that it's an impurity in the DIEA that causes the
problem. Acetylation is minimal when coupling standard amino acids, but with
slower couplings the side reaction can occur faster than the desired reaction.
Paul Alewood has also presented a poster on this issue. I believe his
conclusions were the same. I'm not sure if either poster gave any
recommendations for circumventing this side-reaction. If anybody from the above
mentioned labs is listening, maybe they can add that info.
If you get a solution posted privately, please share it with the group. I'd like
to hear it.
Good luck!
Jeni
Janelle Lauer
Florida Atlantic University
Department of Chemistry and Biochemistry
777 Glades Road
Boca Raton, FL 33431
jlauer@fau.edu
Phone: (561) 297-2094
FAX: (561) 297-2759