From: E.braswell <BRASS@UCONNVM.UCONN.EDU>
  To  : Karen Fleming <rasmb@bbri.org>
  Date: Thu, 24 Jun 99 14:16:45 EDT

Low molecular weight

Karen,  Two things easy to do: 1) Do calculate the possible charge from the
AA composition (use "sedenterp").  This will give an indication of whether
you have to worry or not.  2) Do calculate, using some version of Trout's
Rule, the vbar of the organic part and so the vbar of the whole molecule.
You still need a pretty accurate density meter to do the Edelstein-Schachman
method (which I have done successfully) since you must know fairly accurately
the density of the D2O used (it exchanges with the water in the air)
so as to assess it's purity for the corrections necessary to the method for the
deuteration of replaceable hydrogens.. There is a general rule for the average
protein, but you may have some on the organic part as well.  Regards, Emory

Emory H. Braswell
Professor of Biophysics and Head,
National Analytical Ultracentrifugation Facility
U-125
University of Connecticut
Storrs, CT 06269-3125
TEL 860 486 5032
FAX         5005
E.BRASWELL@UCONN.EDU