You asked the following question:
"but Matt how do you detect an aggregate like
protease-inhibitor or coil-coil or cysteine bridge aggregates by light
scattering?"
The answer is that you look at different concentrations. A
covalently-linked aggregate/oligomer (eg: cysteine bridge aggregates) will
not increase in molecular weight with concentration but a
non-covalently-linked one will. The non-covalently-linked aggregates
such as coiled coils will just show their native molecular weight ie that
of the oligomeric unit (of course for coiled coils in light scattering
one has to take into account the shape as in size exclusion
chromatography). Incidentally analytical centrifugation can give you
molecular shape info as well as molecular weight by looking at the rate
of sedimentation or the final concentration distribution respectively.
Having said all that - I agree totally with you about using size
exclusion as a quick method and as a preparative method for the NMR
samples which was tghe original point anyway I 'spose! Must have slipped
into pedantic mode temporarily :)
Happy Researching
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Matt Hicks
Centre for Biomolecular Design & Drug Development
School of Biological Sciences
University of Sussex
Falmer
BN1 9QG
UK
Tel: +44(0)1273 678923
Fax: +44(0)1273 678433
email: matth at biols.sussex.ac.uk
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