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
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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.
...
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