[RASMB] AUC in ficoll

[jack kornblatt]

Hello All
It might be worth adding to the points mentioned that ficoll is a  
highly branched polysaccharide and that it is not a "neutral" component 
of a mixture.
There is an extensive literature on molecular crowding and osmotic 
stress. Compounds such as dextran and PEG (and Ficoll by association) 
certainly sediment but the osmotic pressure that they develop in the 
water column is probably not by any stretch of the imagination 
non-negligible. Whether you are in favour of the Timasheff explanation 
or the Parsegian explanation of what the equations mean does not matter. 
What is important is recognizing that 100 mg/mL in your buffer is not a 
simple analysis problem.
jack kornblatt