We see BME adducts in all of our estrogen receptor structures, though we don't always put them in the models. Sometimes we only see one or two atoms of the adduct, and in others it is completely ordered. We only see it on the solvent accessible cysteines. We do it on purpose. We used to treat the protein with iodoacetic acid to generate uniform modification of the cysteines, but then we realized we could get then same homogeneity with 20-50mM BME.
Kendall Nettles On Apr 15, 2011, at 4:09 PM, "Michael Thompson" <mi...@chem.ucla.edu> wrote: > Hi All, > > I was wondering if anyone knew whether or not it is possible for reducing > agents with thiol groups, such as DTT or beta-mercaptoethanol (BME), to form > covalent S-S bonds with Cys residues, particularly solvent-exposed Cys? I > have some puzzling biochemical results, and in the absence of a structure > (thus far), I was wondering if this might be something to try to control for. > I have never heard of this happening (or seen a structure where there was > density for this type of adduct), but I can't really think of a good reason > for why this wouldn't happen. Especially for something like BME, where the > molecule is very much like the Cys sidechain and seems to me like it should > have similar reactivity. The only thing I can think of is if there is a > kinetic effect taking place. Perhaps the rate of diffusion of these small > molecules is much faster that the formation of the S-S bond? > > Does anyone know whether or not this is possible, and why it does or does not > happen? > > Thanks, > > Mike > > > > > -- > Michael C. Thompson > > Graduate Student > > Biochemistry & Molecular Biology Division > > Department of Chemistry & Biochemistry > > University of California, Los Angeles > > mi...@chem.ucla.edu
