[RASMB] why use different loading concentration for sedimentation

[Borries Demeler]

> 
> Hi, 
> 
> I am investigating the oligermer status of my interest protein. And I
> noticed a lot use different loading concentration at one run and
> combine the data sets and fit them. I want to know what more
> information can more than one loading concentration can give me and
> use what program to fit this group of data.

Different speeds allow you to generate different equilibrium profiles
for the same sample - the same is true for different wavelengths, which
allow you to observe the concentration dependence of oligomerization
under different concentration ranges. Then you can globally fit all
observations to a model of a reversibly self-associating system, taking
into account *all* speeds and concentrations. Think of it as taking a
picture of an object from many different angles, you will end up with
a better description than just having taken a picture from a single angle.

I wrote a short mini-tutorial on how to design your equilibrium experiment.
Take a look at:

http://www.ultrascan.uthscsa.edu/tutorial/equil_tutorial.html

For guidance on how to analyze global equilibrium data with UltraScan, refer to:

http://www.ultrascan.uthscsa.edu/manual/equil1.html

Good luck, -Borries