We can quantitate down to 50 pmol Nle in a 75 microgram hydrolysate,
which usually puts us in the 0.2-0.5% Nle/Met replacement range. Most
AA peaks are off-scale, but you can get molar quantitations based on
proline.
-- Reed Harris Genentech, Inc. (650) 225-4187 Phone (650) 225-3554 FAX reed@gene.com E-Mail
> 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