[RASMB] Hydration of DM/OG cont...

[Lustig]

Dear Fumio and John H.and colleagues,
actually you asked  2 questions,Fumio.To the first one, it is known may 
be  about 50 years
that  the density  of BSA (and also myself measured different prot's.)is 
about  ro= 1.35 in  Water/buffer and mesured in CsCl or high
concentrated  other salts or sugar the density ro= 1.25 -1.28. Now the 
reason is the
preferential solvation*(What I called the water-shell. *(see Greg Ralstones 
Beckman booklet:
Introduction  to AU) .So the lower ro stems by including  a certain amount 
of water to  the protein or detergent  particle.I don't want to enter in 
the anhydros  prot determination and what we are measure in  a pycnometer, 
but there the water in the particle is close to the outside buffer/water.
The second question .To be able to get a reasonable ro difference between 
solvent and solution ,
the solution  must be of a concentration that induces a readable signal. 
Under CMC solutions
are usually below this range, and as I previous said , CMC may be different 
from case to case.
What is the right  solvent for a  detergent micelle  determination? the 
buffer or the buffer include
a under CMC detergent  concentration ...open questions.
You can extrapolate only with a straight line, but in the  "crossover" - 
range , my observation  was
that the  line is not straight.
I have only a XLA not a XLI and in the model E with  interference you cant 
expand the fringesas in the XLI.
     yours  ariel