E.coli recombinant protein proteolysis

[Rob]

Can anyone help please..

We've been trying to express a pro-hormone as a GST fusion in E. coli
(DH5-alpha) but seem to be having problems with proteolysis - we think this
may be occuring at double basic sites but are not completely sure.

Has anyone 
a) had similar problems
b) been able to solve the problem by using e.g. JM105s or BL21s
c) tried inhibiting endogenous coli proteases (i.e. whilst they are
growing) by adding protease inhibitors to the broth (will they get into the
cells ?)

Thanks in advance

Rob Layfield