<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<meta content="text/html;charset=ISO-8859-1" http-equiv="Content-Type">
</head>
<body bgcolor="#ffffff" text="#000000">
Hi Jack,<br>
we have encountered similar problems in the past, usually with
interference optical data where either our collaborators didn't give
use the right buffer, or I picked the wrong one, or the buffer exchange
didn't work out. SEDFIT currently has models for evolving baseline
curvatures arising from (unmatched) sedimentation of buffer components
in the reference sector. In our hands, this has worked very well in
most cases. This was not yet publicly released and announced, simply
because we didn't have the time to write it up. I can walk you through
how to use it. <br>
Peter<br>
<br>
<br>
<br>
Jack Kornblatt wrote:
<blockquote cite="mid:46EE9C57.8030801@alcor.concordia.ca" type="cite">
<meta content="text/html;charset=ISO-8859-1" http-equiv="Content-Type">
<title></title>
<font size="+2"><tt>I have checked the RASMB archives and there does
not seem to be anything on this particular subject.<br>
The problem is not the XL-I; the problem is an overly complex sample
and reference.<br>
<br>
The sample contains a protein that absorbs at 290 nm as well as a
ligand that absorbs at 290 nm.<br>
The reference contains just the ligand. Both are in matching buffers.<br>
<br>
The first scan: The baseline absorbance starts below zero and becomes
more negative at higher radius.<br>
Scan 100: The sample has almost sedimented completely giving the
baseline absorbance what appears to be a "bow". <br>
Scan 200: The sample has sedimented completely and the absorbance is
well below zero. It is more negative at high radius than low radius.<br>
<br>
The problem is clearly the sample. I have not run the "control" in
which the sample compartment contains no protein but does contain
ligand; reference compartment contains no ligand.<br>
<br>
This problem must have come up in the past. Needless to say, all
analyses are feasible but they are not likely to be correct. I'm at
wits' end.<br>
<br>
thanks for any help you can give. i am attaching an xlgraph of the
three scans.<br>
jack kornblatt<br>
</tt></font>
<pre wrap="">
<hr size="4" width="90%">
_______________________________________________
RASMB mailing list
<a class="moz-txt-link-abbreviated" href="mailto:RASMB@rasmb.bbri.org">RASMB@rasmb.bbri.org</a>
<a class="moz-txt-link-freetext" href="http://rasmb.bbri.org/mailman/listinfo/rasmb">http://rasmb.bbri.org/mailman/listinfo/rasmb</a>
</pre>
</blockquote>
</body>
</html>