From: Henryk Eisenberg <BPEISENB@WEIZMANN.WEIZMANN.AC.IL>
  To  : Dr. David J. Scott <djs17@york.ac.uk>
  Date: Thu, 22 Apr 99 10:02:13 +0300

Partial specific volume in 3M GuHCl

When you investigate multicomponent systems, and in particular
high cosolvent concentrations, you cannot use calculated partial
specific volumes in the analytical ultracentrifuge, you must use
experimentally determined density increments drho/dc determined
at dialysis equilibrium. For a recent discussion compare Fujita
in Modern Analytical Ultracentrifugation, Schuster and Laue,editors,
1994,pp 3-14. The problem is that you are not looking only for the value
of the molecular weight to some approximation, but usually for something
more complex, for instance the number of subunits in a native protein.
For an early discussion concerning the number of subunits in rabbit
muscle aldolase compare Reisler and Eisenberg, Biochemistry, 1969, 8,
4572-4578. More recent discussions in Eisenberg, Biophys.Chem., 1994,
53, 57-68.
Henryk Eisenberg, Structural Biology, Weizmann Institute of Science,
Rehovot, Israel