Re: Chromatography and methionine

Richard Laursen (laursen@bu.edu)
Fri, 20 Nov 1998 16:34:28 -0400

If you are just doing analytical work and don't need to recover the
proteins, maybe you could do a mild oxidation of the methionines to the
sulfoxide. [Perhaps someone out there knows a procedure.] This would
significantly change the polarity/hydrophibicity of the Met residues, and
may allow separation of the Nle and Met variants by RPHPLC.

Richard Laursen
---------------------

>We are working with an E.coli-produced recombinant protein (21,000 MW, 3
>methionines, no cysteines) that apparently has some methionine-to-norleucine
>variants. One of these variants chromatographs very closely to the parent
>protein across a number of purification techniques: cation and anion exchange,
>HIC, acid rpHPLC. Does anyone have any suggestions about how to specifically
>enhance resolution between these species, so we can quantitate the variant
>without doing a peptide map?
>
>Vernon
>
>Vernon A. Shoup
>Regeneron Pharmaceuticals, Inc.
>Rensselaer, NY 12144
>
>(518)488-6012
>vernon.shoup@regpha.com

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>