From: Henryk Eisenberg <BPEISENB@WEIZMANN.WEIZMANN.AC.IL>
  To  : Marina Mapelli <Marina.Mapelli@EMBL-Heidelberg.DE>
  Date: Tue, 13 Apr 99 16:41:33 +0300

Analysis of ultracentrifugation data

Dear Marina:
You have received many answers to your question how to analyze
protein ultracentrifugation equilibrium data in 20% glycerol and
300mM salt. I am surprised that you were not told that in order to
analyze these data correctly you have to determine a density increment
drho/dc by dialyzing a sample of your material against the solvent used,
and determining the density difference between the solution and the
solvent at dialysis equilibrium.This term replaces the (1-vbar.rho) term
in two component systems. You can then use Eq. 5 in H.Eisenberg, Biophys.
Chem., 53 (1994), 57-68. In this paper you will find earlier references
to the analysis of multicomponent systems, the Casassa&Eisenberg paper
Adv.Prot.Chem.19 (1964), 287-395, the Eisenberg book Biological Macro-
molecules and Polyelectrolytes in Solution (Clarendon Press Oxford, 1976),
and many more.
I hope this will be helpful and you have enough material to perform the
dialysis and the density measurement. Less than 2ml of solution of OD
about unity are required and the Anton Paar Kratky-Porod precision
densimeter. You require an OD value to determine the concentration of
your protein. If you have any problems Ariel Lustig at the Biozentrum
in Basel can most likely help you,
Good luck and success, Heini

H.Eisenberg, Structural Biology Department, Weizmann Institute of Science
Rehovot 76100, Israel. Tel 972-8-934 3252, Fax 972-8-934 4136
bpeisenb@weizmann.weizmann.ac.il