[Protein-analysis] equilibrium const for disulfide bond formation

juicymixx At mailinator.com via proteins%40net.bio.net (by juicymixx At mailinator.com)
Tue Jan 9 14:18:04 EST 2007


This is a pretty simple question; however I can't seem to find an
answer to it.   I have a rather small protein (60 amino acids) in which
I've mutated in a single cysteine for labeling purposes.   There are no
other cysteines in the protein.   Additionally the protein is normally
unstructured in solution (that is in 30uM phosphate buffer at 25C,
there is no significant structure).   Recently we've noted that after
purifying the protein (but before labeling it) we appear to have some
dimer formation which isn't seen in the wild type protein.

I was just wondering what the equilibrium constant (reaction rate,
etc.) for intermolecular disulfide formation from 'free' cysteine would
be (or better yet, cysteine in a polymer/peptide/protein).   Someone
has probably already done this experiment, however I'm not sure of
where to look for this number...


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