[RASMB] lower molecular weight

Borries Demeler demeler at biochem.uthscsa.edu
Wed Jan 26 08:30:01 PST 2005


> 
> Dear all,
> 
> Some time ago I asked around for the highest measurable molecular weight by analytical ultracentrifugation. This time a colleague asked me whether it is possible to measure host-guest complexes by analytical ultracentrifugation in which the host is around 1500 Da and the guest around 500 Da. I checked literature on this more supramolecular chemistry related research (in contrast to the more biochemical research normally done by AU) and so far without any luck. Could someone help me with a lead? To me it seems to be possible, although one needs to spin the sample pretty fast. Apart from this question: what would be the experiment of choice? Sedimentation velocity or sedimentation equilibrium?
> Thanks!
> Kind regards,
> 
> Joris Beld
> Swiss Federal Institute of Technology
> Hilvert Group

Joris,

I have successfully measured samples in this size range. As you already
indicated, you will need to spin fast to make this stuff move in the AUC.
I'm afraid that you won't get a typical sedimentation velocity expt. to 
work, unless the sample is associated as a multimer and you run at 60k.
But an equilibrium expt. with 3 speeds between 50k and 60k should give you
some useful data.

Good luck, -Borries



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