Hi Phil,
Depending on the characteristics of the c-terminal region of interest, you might try a carboxypeptidase. These enzymes cleave residues from the c-terminus and stop at various motifs, depending on the specific enzyme. There are several available commercially, each having a slightly different activity. Also, the following paper may be of interest:
Current strategies for the use of affinity tags and tag removal for the purification of recombinant proteins
José Arnau, Conni Lauritzena, Gitte E. Petersena and John Pedersena
Protein Expression and Purification, Volume 48, Issue 1, July 2006, Pages 1-13
Good Luck,
Mike
----- Original Message -----
From: "Philipp Ellinger" <[log in to unmask]>
To: [log in to unmask]
Sent: Wednesday, February 23, 2011 1:17:33 AM GMT -08:00 US/Canada Pacific
Subject: [ccp4bb] off-topic: tag removal
Dear all,
I have a question concerning removal of a his-tag sequence.
We have crystallized a protein with an important feature at the C-terminal part of the protein.
Unfortunately, we cannot express it with a N-terminal his-tag, only with a C-terminal his-tag.
Therefore we are looking for a protease which cleaves off the sequence without leaving any extra amino acid on the C-terminus of our protein. Meaning we obtain really the wild type protein.
Does anyone know about a protease or cleavage site which is completely removed?
Many thanks in advance
Phil
--
Michael C. Thompson
Graduate Student
Biochemistry & Molecular Biology Division
Department of Chemistry & Biochemistry
University of California, Los Angeles
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