N-terminal degradation of Recombinant protein

[Dr Engelbert Buxbaum]

Russell Wrobel wrote:

> I'm part of a structural genomics group and we do high though put 
> protein production in E. coli. N-term. tags can usually be cleaved off 
> after protein purification with site specific proteases.  In our program 
> we have had good luck expressing things with an N-term maltose binding 
> protein (MBP) tag.  After purification we remove the tag using TEV 
> protease.  There are several commercially available expression systems 
> that rely on the cleavablity of solubility tags.

MBP is a wonderful aid for expressing proteins in bacteria, it keeps
them stable and soluble. However, in many cases affinity purification on
sugar-columns does not work. I had MBP-cyclins once which I had to
purify by conventional means (AS precipitation followed by SEC and IEC)
because of this problem.

I recently saw a paper (Protein Science, IIRC) where authors suggested
an additional His-tag N-terminal of MBP to get the stabilisation of MBP
and the easy purification of Oligo-His.