Dear colleagues,
We are currently confronted with a precipitation problem in peptide
synthesis. For a customer we synthesized a Leu-pentamer. After cleavage
from the resin I acquired a MALDI spectrum of the raw product which showed
a mixture of the tetra- and pentamer (approx. 1:1). When we tried to
precipitate the peptide with diethylether after cleavage nothing happend.
We still have a nice clear solution even after storing it at -80ƒC over night.
Does anybody of you have an idea about how to precipitate the peptide?
Would eventually addition of something more hydrophobic (e.g. pentane or
hexane) help or will this lead to a phase separation between the organic
phase and the TFA? Has anybody of you already tried to synthesize this
sequence and how did you circumvent the problem? Since the synthesis itself
of the sequence worked better than I expected, we will also try to sequence
(Leu)10 for the same customer. Does anybody have any experience with this
sequence as well? Should we maybe try to synthesize a pentamer, cleave of
halve of it, protect the free peptide with Fmoc-OSu and use this as
building block to finish the decamer?
Any hints are greatly appreciated! Thanks in advance.
Marcus Macht
********************************************************
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
**************************************************************************
This archive was generated by hypermail 2b29 : Fri Oct 06 2000 - 12:35:07 EDT