One possibility is to use the endoproteinase Arg-C (sold by Boehringer Mannheim
among others), a protease that should specifically cleave C-terminal of Arg
residues. I have however not used that enzyme myself and I vagely remember
hearing or reading that the enzyme activity was not as robust as one could hope.
Maybe some ABRfer may wnat to comment on this. Another possibility is to
denature the protein, reduce/alkylate the Cys and to derivatize the Lys with
maleic acid anhydride (the two steps can be performed together), and then to
digest the protein with trypsin. Since the Lys are now derivatized, trypsin will
only cleave after arginines.
Hope that it helps
Axel Ducret
Philip Majerus wrote:
> I have need to cleave a large protein at R in order to identify a
> particular carboxymethy cys residue. Greg Grant suggested that I poll the
> group for advice as to a suitable protease and protocol to do such if there
> is one available. I have about 500 pmol of tritiated protein that is mr
> 140000. Thanks for your help Phil Majerus
>
> Phil Majerus
-- Axel Ducret, Ph.D. Senior Research Biologist Merck-Frosst Canada Inc. Dept. Biochemistry and Molecular Biology P.O. Box 1005 Pointe-Claire-Dorval PQ H9R 4P8 Canadatel. + (514) 428-3428 fax + (514) 428-4900