using TOPP cells for protein expression?

[Stefan Trentmann]

Dear  netters,

is there anyone out there who has tried the TOPP cells sold by 
STRATAGENE for overexpression of difficult-to-express proteins? Any 
comments are appreciated to get an idea if it is worth testing them.

I am working on a protein that I cannot get expressed in E. coli K12. What 
would you recommend me to do? Should I directly switch to yeast or 
Bacculo virus?
I am using the pEXP expression vector and have tried different strains 
of E.coli K12 for overexpression (M15 which comes with the pQE expression system from 
Qiagen, W3110 as well as DH5 alpha). The correct cloning was 
confirmed by sequencing through the cloning site. Except for W3110 
the strains stopped growing after induction with IPTG.

I am thankful for any suggestions

Stefan Trentmann
Ruhr-Universitaet Bochum
Germany