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<DIV style="FONT: 10pt arial">----- Original Message -----
<DIV style="BACKGROUND: #e4e4e4; font-color: black"><B>From:</B> <A
title=ychen5@unity.ncsu.edu href="mailto:ychen5@unity.ncsu.edu">Yun-Ru (Ruby)
Chen</A> </DIV>
<DIV><B>To:</B> <A title=rasmb@rasmb-email.bbri.org
href="mailto:rasmb@rasmb-email.bbri.org">rasmb@rasmb-email.bbri.org</A> </DIV>
<DIV><B>Sent:</B> Friday, May 31, 2002 2:37 PM</DIV>
<DIV><B>Subject:</B> Can 0.25M of NaCl take care of nonideal behavior of a
protein? </DIV></DIV>
<DIV><BR></DIV>
<DIV><FONT face=Arial size=2>Dear RASMB members:</FONT></DIV>
<DIV><FONT face=Arial
size=2>
I have currently run into problems by analyzing my data from sedimentation
equilibrium studies. I am very confused and frustrated about
it.</FONT></DIV>
<DIV><FONT face=Arial size=2>I hope if any of you can give me some ideas. I
am working on a 10KDa protein domain which is suppose to be a helical bundle.
The pI of the protein is calculated to be about -1.5 at pH 8. I have ran the
samples in two different buffers, one in 30 mM Tris, pH8, and one in
Tris with 250 mM NaCl. Both buffers contain 0.2mM DTT and are
at pH 8. However, we cannot fit all the data to a single assembly
model. I have tried to put in different guesses of "B" values for
nonideality, but the fits are even worse. Moreover, the data from
the salt buffers look better then the one without. Therefore, does that
mean 0.25M NaCl is not enough or there is something else that I should be
aware of? My protein is much less soluble in the presence of NaCl,
so it is a bit hard for me to increase to salt concentrations.</FONT></DIV>
<DIV><FONT face=Arial size=2>Thanks very much if you can share
your idea with me.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>Sincerely,</FONT> </DIV>
<DIV><FONT face=Arial size=2>Ruby</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>Yun-Ru (Ruby) Chen<BR>Ph.D. candidate<BR>Department
of Structural and Molecular Biochemistry<BR>North Carolina State
University</FONT></DIV></BODY></HTML>