I've seen BME adducts many times both in structures and via MS. DTT adducts are somewhat less common (due to intramolecular disproportionation into oxidized DTT and free SH) but still observable:
http://www.ncbi.nlm.nih.gov/pubmed/11684092 So - not only is this possible, but practically commonplace, especially with BME. In general if something is chemically possible -- it's almost certainly going to be found in biological world. That's not very remarkable since biological systemsplay by the same exact rules as chemical ones. What's perhaps much more remarkable is that biological systems routinely perform chemistries that most synthetic chemists would find to be nearly impossible, or entirely impossible in aqueous environment. This just goes to show that billions of years of molecular (and other) evolution are hard to beat. Artem On Fri, Apr 15, 2011 at 3:09 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 >
