>Dear All,
> I have a colleague who has two peptides (KKKKKRKREK-NH2, and
>KKKRRSREK-NH2 which elute with the salt from a C18 column. does any one
>have a suggestion or two for purification of these peptides.
>
>--
>Chris Wood
Chris
This is a perfect opportunity to use a WCX chemistry, since there are
so many positive charges. If you use a SCX chemistry, you would need
a substantially greater amount of salt for elution.
Since the number of charges here are 10 vs. 7 you can use either an
acetic acid or a salt gradient to get them apart. If want to have
volatile elution conditions start with 5mM HOAc and run to 20% HOAc.
See: http://www.nestgrp.com/pdf/Pp1/PolyCAT_Acetic_Acid.pdf for
examples. Otherwise, use 15mM phosphate buffer at pH 6.0 and run a
NaCl gradient to ca. 500 -700mM. The salt concentration difference
for elution should be on the order of 150mM between them.
Alternatively, use either of these columns in the HILIC mode (bind at
90% MeCN in 15mM ammonium formate, pH 6.5, and elute with a gradient
to 40% MeCN). See http://www.nestgrp.com/pdf/Pp1/HILIC_SEC-SCX.pdf
for general conditions and references.
Best of luck.
Sincerely,
Amos Heckendorf
-- Amos Heckendorf, Ph.D. (amos@nestgrp.com)The Nest Group, Inc., Value Added Resellers of HPLC Columns (VydacÅ, PolyLCÅ, Jordi-GelÅ, Macherey-Nagel NucleogenÅ, Higgins Analytical HAISilÅ LS, TARGAÅ & CLIPEUSÅ, and Nest Group MACCELÅ) SAI flash chromatography cartridges; and AmiKa Harvard Bioscience BioDialyserÅ, Dispo-BioDialyserÅ , 96-Well Dialysis Plates, and SuproTipÅ MS and MiniSpin SCX MicroSample SPE Tips for proteomics.
Tel: 800-347-6378 or 508-481-6223; FAX 508-485-5736; 45 Valley Rd, Southboro, MA 01772-1306 Applications and Protocols at our NEW site: http://www.nestgrp.com/protocols/protocol.shtml
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