While on the solubility issue, would anybody comment on this problem:
We made and have been purifying by batches when needed the beta amyloid
1-42 peptide. All the batches were fine according to our QC checks; single
peak on HPLC (albeit at 55C), identical retention time, perfect aaa and ms.
However, a research lab says the latest batch of the purified won't
dissolve well in H2O. I believe that they make a 1 mM stock and insist that
10mMol stocks should be possible in H2O. Even 1 mM sounds high to me but
thats not my bailiwick. Assuming that everything is the same at their lab.,
I wonder what could be happening. I'd be interested in knowing if anyone
has had any similar problems of this type. (purification was on a C4 column
in a 0.1%TFA/ACN gradient system)
Thanks in advance,
Dick Cook
P.S. some of my ABRF notes on previous answers to solubility problems:
TriFluoroethanol TFE and HFIP hexafluoroisopropanol used to dissolve
protected peptides.
1/97
Dear Sajith,
I usually use dioxane with small amounts of water to dissolve
hydrophobic peptides, particularly since this solvent system will lyophilize.
I have found that a mixed solvent system sometimes works better, for instance,
acetic acid with about 5% water and, as mentioned, a dioxane-water mixture. If
all else fails, I use TFA (remember, with Fmoc synthesis, TFA is the cleavage
reagent and the solvent). One can then precipitate the peptide with ether or,
as I usually do, remove the TFA on a rotary evaporator, suspend the peptide in
a suitable solvent (sonication helps here) and lyophilize. I hope this helps;
some peptides are pretty stubborn.
-- Eunice York (eunice@kinin.uchsc.edu) Dept. of Biochemistry, B-126 University of Colorado Health Science Center 4200 E. 9th Ave., Denver, CO 80262 Phone - (303) 315-4879 or 7514 Fax - (303) 315-8215We have had some success with hexafluoro-2-propanol for solubilization of very hydrophobic peptides (corresponding to transmembrane single domains). I found the trick in Bionet about 2 years ago (???), you probably can find the original discussion in the molbio.methds-reagents group archives at : http://www.bio.net/
Hope this helps, Good luck
Pierre