 |
 |
Dear Jose Your email expressed far more clearly than mine the problem of symmetry, and I had completely forgotten this discussion in the classic MWC paper. The point about measuring the molecular weight in solution is to find IF the protein forms an oligomer or not - AUC can give some idea of shape (cigar or hamburger) but cannot give any further indication of asymmetry as SAXS can. However, if you find a monomer in solution, Hay's problem is solved. When you state however that it is highly unlikely for a homo-oligomer to show asymmetry, I think you are forgetting the well-known phenomenon of half-of-sites reactivity among enzymes. A simple internet search will in fact show many examples where two copies of the same molecule form a complex, adopting different conformations to do so. Symmetry-breaking is a general feature of Nature, so it is not too surprising that proteins may adapt to a partner's presence in this way. The bottom line is that MWC assumes symmetry, and this assumption is not always valid. Like Hay I would like to know of higher-order examples than dimer, as my group has some interesting symmetry-breaking results coming out... best wishes Jeremy ****** On Dec 12, 2014, at 4:56 AM, Jose Manuel Duarte wrote: Dear Hay Your post prompted me to respond, since I think the issue of symmetry is extremely important. ...