(no subject)
Richard Laursen (laursen@bu.edu)
Mon, 28 Sep 1998 13:08:44 -0500
One way is to prepare a small column containing a strong anion exchanger
(QAE-Sephadex, QAE-cellulose, etc.). Exchange all the anionic sites on the
resin with the desired anion (e.g., sulfate; but it could be bicarbonate,
chloride, etc.) by eluting with a strong (1M) solution of corresponding
salt (sodium sulfate). Then wash out the excess salts with water. This
will give you a sulfate column. Then dissolve the peptide in water and
pass it through the column, and collect what comes through, which should be
the peptide in the desired ionic form. It is important, though that the
peptide be above its isoelectric point (i.e., be neutral or have a slight
positive charge) or it will itself be an anion and stick to the support.
Also the column should cont at least a 10-fold (better 50- to 100-fold)
excess of anion sites over peptide sites.
This procedure is a bit involved, but it can be scaled to any amount of
peptide and also used to to exchange any anion.
Richard Laursen
----------------------------------------
>Hi
>Does anyone know a way to exchange TFA salt in petides with other
>salts then Cl or acetate ?
>Thanks in advance,
>Karolina
Richard A. Laursen
Department of Chemistry
Boston University
590 Commonwealth Ave.
Boston, MA 02215
Tel (617) 353-2491; FAX (617) 353-6466
email: <laursen@bu.edu>