GST-fusion protein breakdown

Dima Klenchin klenchin at
Thu Apr 3 11:04:13 EST 1997

In article <eupoh5.aso.ln at>, krasel at (Cornelius Krasel) wrote:
#marcvdc at wrote:
#> Our GST-fusion protein is well expressed in E. coli and it is soluble, but it
#> runs about 8kDa lower than expected on PAGE. I fear we have breakdown of the 
#> fusion. 
#> Does anyone know a solution for this problem ?

Actually, if ALL of it is lower, it does not sound like proteolysis problem. 
"Lower" in comparison with what? This 8K could be sugars!
If not, than it's possible that for some reason termination occurs with
100% efficiency earlier than intended. Was the construct verified?

#I am afraid there is no easy solution.
#You may try:
#- Changing of E. coli strain (to protease-negative strains, like BL21)

Strange as it is but rarely makes any difference.

#- Inclusion of protease inhibitors when preparing the protein

Should be done by default. 

- Dima

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