Dear Rachel,
I have used a mixture of 20% piperidine in DMF a couple of times and it
worked quite well. Using DMF solution you can precipitate your peptide
afterwards as usual with Et2O and use the normal workup procedure.
Somebody also posted a message in this group that neat piperidine will also
work. I tried this and it cleaved; unfortunately not only the Fmoc group
but the complete peptide into small pieces, so please be careful with this
kind of recipe.
Just for curiosity: Is the peptide still completely Fmoc protected or do
you just want to remove the remainings of an incomplete deprotection step?
If the latter one is the case, how did you determine the Fmoc content? In
my experience e.g. MALDI-MS usually shows a horrible amount of uncleaved
Fmoc-peptide (sometimes 50% or even more) while in fact (according to HPLC
at 215 nm) it is most likely below 5%. This is probably due to an very,
very much better desorption of the Fmoc-peptide (maybe because of an
extremly efficient energy transfer upon the Fmoc group (comments
appreciated...)? Fmoc cleavage can be monitored by UV absorption between
300 and 320 nm , the N2-laser has a wavelength of 337 nm...).
Yours sincerely,
Marcus Macht
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Dr. Marcus Macht
University of Cologne
Centre for molecular medicine - Service laboratory
Joseph-Stelzmann-Str. 52
50931 Cologne, Germany
Tel.: +49 221 478-6995
Fax: +49 221 478-6977
e-mail: Marcus.Macht@uni-koeln.de
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