[RASMB] again about densities of OG+DM

[Lustig]

Dear John Harlan , Fumio  and colleagues,
I'm not astonished  that  you =John report on a bit different  Vbar values 
as I have done.
The deviation of detergent  micelles densities  stem from several reasons.
We have to understand that a detergent solution is mixture  of under and 
over CMC.
This equilibrium of particles may  differ  by concentration and  used 
buffer/water.
In density-meters you  need  to  know  the  real concentration of micelles 
and this
is  quasi impossible for the Vbar determination, where you have to cross
the under CMC range.
In AUC you can determine the micelles density  with schlieren  and 
interference
in densifiers between sedimentation and floatation, but  this densities are 
hydrated once.
with a water shell so they are 40-50% off.
Different producers of detergents reports on  different subunits for a 
micelle so
also the density variegates.
The reference of Shire (15 of the BBA paper I sent to Fumio) gives also 
different values
as the Meth.of Enzymology.if not to trust in my own measurements.

                                                                                                Yours....ariel