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Dear Chad, dear all,<br>
<br>
there might be another source of the hiccup. It seems as if at least
two of the scans (red and green) are sort of parallel shifted on th OD
axis. It might be a (faulty) effect of the high voltage regulation of
the PM - of the sort you have if you try to gather intensity data from
samples in reference and sample channel. By the way, if my impression
is correct it shoulf show up in the residuals of the fit.<br>
<br>
Best wishes<br>
<br>
Claus<br>
<br>
<pre class="moz-signature" cols="72">Prof. Dr. Claus Urbanke
Medizinische Hochschule
Abtlg. Strukturanalyse OE 8830
Carl-Neuberg Str. 1
D-30625 Hannover
Tel.: +49 511 532 9372
FAX: +49 511 532 5966
</pre>
<br>
<br>
Chad Brautigam schrieb:
<blockquote
cite="mid:FE3CCAB2-03F6-4CFE-B060-55DE4073375B@UTSouthwestern.edu"
type="cite">Dear All,
<br>
<br>
Whilst checking the data from the first speed of a sedimentation
equilibrium run, I noticed a troubling discontinuity in the data. It
appears in all three cells, and it is not exactly subtle. The jump in
the data can be as much as 0.1 OD, and it always occurs betwixt 7.05
and 7.06 in radial space. The anomaly occurs at both 280 and 250 nm.
I attach a graph of three successive scans from the same cell, spaced
four hours apart, for your delectation. The data were collected in
stepping mode, with 20 replicates.
<br>
<br>
While I suspect that the heavily glycosylated protein in these samples
might behave nonideally, I suspect that the real problem here is
instrumentation, maybe a sticky rail. But, before calling my service
rep, I thought I'd tap the collective wisdom of the AUC hive mind.
<br>
<br>
And a further question: do y'all think that these data can still be
analyzed if I simply exclude the affected region from the analysis?
I'm running in the 6-hole centerpieces, so that means I'd be
eliminating about half of the data from the outer holes. Alas.
<br>
<br>
Thanks for any insight you can provide.
<br>
<br>
Best,
<br>
Chad
<br>
<br>
<br>
<br>
<br>
======================================
<br>
Chad A. Brautigam, Ph.D.
<br>
Assistant Professor
<br>
Department of Biochemistry
<br>
The University of Texas
<br>
Southwestern Medical Center at Dallas
<br>
Department of Biochemistry
<br>
5323 Harry Hines Blvd.
<br>
Rm. ND10.214G
<br>
Dallas, TX 75390-8816
<br>
Office: 214-645-6384
<br>
Fax: 214-645-6353
<br>
Email: <a class="moz-txt-link-abbreviated" href="mailto:chad.brautigam@utsouthwestern.edu">chad.brautigam@utsouthwestern.edu</a>
<br>
<br>
<br>
<hr size="4" width="90%"><br>
<center><img src="cid:part1.09010106.07010407@mh-hannover.de"></center>
<p><br>
<br>
</p>
<pre wrap="">
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