kDa limit coli expression

[soenke.behrends from utoronto.ca]

Dear All,
does anyone know of a size limit for expression of proteins in E.  
coli? I have not found anything definite neither in the literature nor  
on the internet. Have codon optimized artificial genes pushed the  
limits? What are the largest proteins that have been successfully  
expressed as soluble proteins. Is it reasonable to assume that protein  
expression in E. coli is difficult above 50 kDa and impossible above  
100 kDa?
Thanks for your kind help!
Kind regards
Soenke