[RASMB] smaller protein size than expected

[Leech, AP]

Fang Yi wrote: [to Jim Cole]
> Dear Jim,
> 
> Thanks for your prompt reply. For the analysis, I used the default vbar 
> and density values of 0.73 and 1 respectively.  At 35K, the value of 
> sigma for this protein is only 1.44 cm-2 (ideal  model). The highest 
> speed recommended to run on this specific centrifuge is set to 40K.  I 
> completely agree with you that gel filtration results doesn't help much 
> in this case considering the possibility that the protein might interact 
> with the matrix. Actually that's  why we decided to do AUC.
> Fang
> 

Hello Fang,

Could the SDS-PAGE apparent size be wrong? I agree with Dmitry it
would be a good idea to check by mass spec.

Also your concentrations seem quite high (0.8 to 4 mg/ml by my
calculation). What wavelength were you using and did you check
the baseline (presumably difficult if you are limited to 40000
rpm)? Does the protein have any other strange features e.g.
high charge, possibly causing non-ideality?

Andrew

-- 
Dr Andrew Leech                   *  Head of the Molecular
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