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Hi Chin,<br>
There are three different interfaces for each sample- the air-liquid
meniscus, the centerpiece and the windows. I have seen surface effects
(most frequently surface binding and aggregation) at all three surfaces
at different times. With the fluorescence optics, these surface
phenomena frequently are observed, and can be a nuisance (e.g. you can
observe protein gathered at the air-liquid meniscus peel away from the
surface with time). There are differences from window to window and
centerpiece to centerpiece (of the same kind), suggesting that
cleanliness may be a problem. Our experience is that the
charcoal-filled epon is the least problematic of the centerpieces, and
that these provide the most uniform behavior. For the fluorescence
system, we typically work in the presence of a "carrier" protein (e.g.
ovalbumin) which out-competes the protein of interest for the surfaces.<br>
Best wishes,<br>
Tom Laue<br>
<br>
Qin Zou wrote:<br>
<blockquote
cite="midOF7A68B5FF.3591F9A0-ON05256F9A.0048DA9A-05256F9A.00490242@EliLilly.lilly.com"
type="cite"><br>
<font face="sans-serif" size="2">Dear all,</font>
<br>
<font face="sans-serif" size="2">On behalf of Allen Pekar, I send you
this message to seek any input. Thanks.</font>
<br>
<br>
<font face="sans-serif" size="2">"RASMB Members: John Philo stated
in a 10/24/04 e-mail that "for one type of protein, I see aggregation
induced during the sedimentation velocity experiment, and the extent of
aggregate formation is a characteristic of individual centerpieces (the
specific centerpiece, not just the type). Thus presumably this
represents some sort of surface-induced aggregation." My question to
RASMB members: has anyone observed this behavior for antibodies in
charcoal-filled epon centerpieces? Thanks, Allen Pekar (Eli Lilly
and Company)"</font>
<br>
<br>
<font face="sans-serif" size="2">Chin</font>
</blockquote>
<br>
<pre class="moz-signature" cols="72">--
Department of Biochemistry and Molecular Biology
University of New Hampshire
Durham, NH 03824-3544
Phone: 603-862-2459
FAX: 603-862-0031
E-mail: <a class="moz-txt-link-abbreviated" href="mailto:Tom.Laue@unh.edu">Tom.Laue@unh.edu</a>
<a class="moz-txt-link-abbreviated" href="http://www.bitc.unh.edu">www.bitc.unh.edu</a>
<a class="moz-txt-link-abbreviated" href="http://www.camis.unh.edu">www.camis.unh.edu</a></pre>
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