[RASMB] aggregates data analysis

[Leech, AP]

Hello Joris,

I would expect the "take off point" to move down the cell at higher
speed. Does this happen? Do you have scans for the approach to
equilibrium to see how this distribution develops?

For 280 kDa and 30000 rpm I would also expect everything to be pelleted
at the bottom. Do you have an expected Mw for the sample?

It might be useful to post a plot of the data. If it is not some sort
of artefact then maybe a velocity experiment would be informative.

Best regards,

Andrew


Beld, Joris wrote:
> Dear all,
> 
> I'm spinning a sample which shows -to me- surprising behavior. The raw data of a normal sedimentation equilibrium run of a protein looks always like a half-parabolic curve of the radius versus absorbance (x,y).
> However, this particular sample (protein) shows a different behavior in that the raw data look like a straight line taking off halfway the liquid column (absorbance almost zero) in the sector to the bottom of the cell (absorbance 0.7). Same behavior is reproducible at three different concentrations and three different rotational speeds (10,20,30 krpm).
> How should I interpret these data? Ultrascan does not really 'like' this data as input (although fitting is possible, the residuals look very bad, the fitted Mw -to a single species- is around 280kDa).
> Is this how a heterogeneous aggregating sample should look like?
> Thanks in advance.
> 
> Best wishes,
> 
> Joris Beld
> ETH Zürich
> Switzerland
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-- 
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