I have made peptides like this on many occasions. Unless there is something
wrong with your resin, I believe the peptide did not precipitate. I would try cleaving
cleaving with no more than half per cent water and all other scavengers as
normal. Or, as i'm sure you know, use the ether/water extraction method.
Hi all: I synthesized the following peptide on a Pioneer Instrument using
Fmoc chemistry/HATU-DIPEA activation on PEG-PAL-PS (C-term amide), final
Fmoc off.
Peptide has a C-ter cysteine, two arginines, 4 aspartates, 6 glutamates,
two serines and tyrosines. Peptide-Resin was dried and cleaved with
Reagent K and precipitated into cold t-but-metyl ether. I also ether ppt 4
other peptides at the same time, these four gave me good precipitates, but
the stated peptide did not. I am baffled, the synthesis (based on Fmoc
yields) appeared to be better for this peptide as compared to the other
four, but no apparent yields. I would have expected this puppy to fall out
of solution in ether, any suggestions on what might have happened and what
I might try on the new synthesis?? Thanks in advance for the help, Gautam
Gautam Sarath
N-226, Beadle Center
Protein Core Facility - Center for Biotechnology &
Department of Biochemistry
University of Nebraska-Lincoln
Lincoln, NE 68588-0664
Phone: 402-472-2928
FAX: 402-472-7842
http://www.biotech.unl.edu/P