From: Brian Noland <noland@quorum.tamu.edu>
  To  : rasmb@bbri.harvard.edu
  Date: Mon, 31 Aug 1998 14:23:34 -0500

Measuring Association Constants in 2 M Urea

To whom it may concern,
I would like to measure an association constant for the alpha subunit of
bacterial luciferase in 2 M urea.  In buffer, the alpha subunit is a
weakly associating system with a dissociation constant in the low
micromolar range.  This protein has an equilibrium folding intermediate
which is highly populated in 2 M urea.  I am guessing that the change in
the structure will change the association constant.  For a sedimentation
equilibrium experiment I don't know if there is a way to calculate the
partial specific volume of the protein in 2 M urea.  Also, are there ways
to get good association constants using sedimentation velocity
experiments?  I would appreciate any advice from those who have ideas on
this matter.

Thank you,
Brian Noland

Brian Noland
Dept. of Biochemistry & Biophysics
Texas A&M University
College Station, TX 77843
noland@quorum.tamu.edu
(409) 845-8971