Oxidation of Cysteines in Proteins

Thomas Collet collet at scripps.edu
Thu Mar 12 16:45:54 EST 1992

Dear Netters:

I hope that this posting is appropriate to this newsgroup and 
apologize if this is not of interest to you.

I am trying to get an idea of how the reduction/oxidation-
potentials inside a bacterial cell, inside the periplasm, and
inside the fermentation broth, i.e. outside the bacterial cell,
influence disulfide-formation during protein folding. Maybe
there is someone out there, who has thought about this
problem and tried to attach numbers to the following questions?
Or maybe someone can give me pointers to literature to study?
1)  How does disulfide-formation occur in the mammalian cell,
and how is this process duplicated in systems where mammalian,
disulfide-containing proteins are expressed in E. coli?

2)  It seems to me that in E. coli the oxidation after secretion into the
periplams must be "inorganic", i.e. tied to the oxygen concentration
in the fermentation broth. The oxygen concentration in the broth
should be much higher in a mechanical fermenter than in a shaker
flask. Any comparative numbers?

3)  If the E. coli cell "competes" with cysteine residues for oxygen,
how fast does the inorganic oxidation have to work to be significant
compared to the oxygen uptake of the bacterial cell?

Any help will be greatly appreciated and I would be glad to post
a summary of my findings, if this is of general interest.


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