Oxidation of Cysteines in Proteins

Michael Benedik bchs1b at Elroy.UH.EDU
Fri Mar 13 23:54:21 EST 1992

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.

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

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