[RASMB] time to reach equilibrium

[Holger Strauss]

Hi everybody, 

while we're at it, I'd like to mention some points I've learned from
bitter experiemce:

- the definition of "sedimentation equilibrium" is a functional one, i.e.
no detectable, macroscopic mass transport within the noise of the data. In
a noise-free world, you would NEVER reach the state where there is no mass
transport any more (curious to think that noise does save you in this
case!).

- all calculations (as far as I'm aware) assume a stable, paucidisperse
solution (which is of course what one needs when doing model-dependent
fitting); however, if your preparation is impure/degrades/precipitates,
you still can get an idea of what's going on: does my system reach a
steady-state (i.e. SedEq)? Is there a solubility limit? Is the system
metastable, and some sort of instability occurs after some time?
Using model-free analysis and average parameters (Mn/Mw/Mz), you can get
useful information out of these experiments - provided you're sure your
system is at SedEq, for which the whole theory applies of course.

Cheers, Holger

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Holger Strauss 

Forschungsinstitut fuer Molekulare Pharmakologie (FMP)
Robert-Roessle Strasse 10

13125 Berlin/Germany

Tel: +49 (0)30 94793 - 223 (office)
                     - 316 (lab)

Fax: +49 (0)30 94793 - 169 


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Science is spectrum analysis; art is photosynthesis.

                                                    Karl Kraus