From: Arthur Rowe <Arthur.Rowe@nottingham.ac.uk>
  To  : rasmb@bbri.org, Gunther.Kern@astrazeneca.com
  Date: Mon, 18 Oct 1999 13:17:38 GMT0BST

Re: sedimentation equilibrium runs at high salt concentrati

I would echo everything that Emory says on this topic, especially with regard to the 
vbar problem.  However, there is (at least) one vital bit of information missing - 
namely which optics were used ?  If you were using interference optics and floating 
the baseline, then there is a danger of getting an apparently "single species" fit from 
a range of quite other possibilities !

Regards

Arthur Rowe


From:          Gunther.Kern@astrazeneca.com
To:            rasmb@bbri.org
Subject:       sedimentation equilibrium runs at high salt concentrations
Date:          Fri, 15 Oct 1999 17:23:44 +0200

Has anyone done equilibrium sedimentation experiments at 3.2 M KCl and knows 
how to correct for the effects of those conditions on diffusion? I am looking at a 
protein that is dimer under normal conditions with a dimeric MW of 60KDa. At 3.2 
M salt I do get a MW of 41KDa after correcting for the increase in solvent density 
(1.158g/ml). The curve fits perfectly to a single species. However I have not done 
any other corrections and the distribution curve should be different due to a 
decreased diffusion at high salt concentrations. Any comments on how to correct 
for this are welcome. Thank you very much, 

 Gunther Kern 
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