In article <8217 at riscsm.scripps.edu>, collet at scripps.edu (Thomas Collet) writes:
>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.
>>>>Thomas COLLET at SCRIPPS.EDU
In case you are not aware there is a report of disulfide isomerase from
the periplasm of E. coli by the Beckwith lab. I think it was a recent
issue of cell a few months ago. The implication was this enzyme was
important for the bulk of the disulfide bonds formed in E. coli proteins.
---------------------------------------------------
Michael Benedik
Department of Biochemical and Biophysical Sciences
University of Houston
INTERNET: Benedik at UH.EDU BITNET: Benedik at UHOU
