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<br>
Dear John and Ariel,<br>
<br>
Thank you very much for the information from both of you.<br>
<br>
Actually, I have a question. Ariel, why are the values obtained by
Anton Paar density<br>
meter designated as "not hydrated"? It may be an
elementary question, but both states in <br>
the density meter and ultracentrifuge cell are hydrated, arn't
they? <br>
<br>
Another question to both of you is that as Ariel pointed out, the micelle
formation<br>
of OG and DM may make the measurement difficult. In your
measurement, as the<br>
concentration of the solute increases, the fraction of OG or DM in the
micelle would <br>
increase with respect to the free ones. Does the graph of rho vs. c
still give a straight line?<br>
(Actually, I do not know the cmc of these reagents and the range of
concentration<br>
that you used.) We have recently purchased an Anton Paar
DMA5000. Could you give<br>
any advice concerning precaution of the measurement if we measure it
ourselves? <br>
I suppose the concentrations are estimated from the dry weight of OG or
DM or<br>
can you get the concentration from the number of fringe?<br>
<br>
Thank you in advance. Fumio<br>
<br>
--------------------------------------------------------------------<br>
Dear Fumio and dear colleagues,<br>
the Vbar of OG is 0.867 not hydrated and hydrated
mesured in sucrose or similar<br>
densifiers 0.924 (mesured in the model E)<br>
That of DM is 0.813 (measured in the A. Paar desity-meter) and the
hydrated<br>
one is 0.885 (measured in model E).In my next ? paper
will be the reference?<br>
<br>
OG reference under N$B!<(B15 of Lustig A, Engel A, Tsiotis G, Landau EM,
Baschong W.<br>
" Molecular weight<br>
determination of membrane proteins by sedimentation equilibrium at
the<br>
sucrose or nycodenz-adjusted density of the hydrated detergent
micelle."<br>
Biochim Biophys Acta. 2000 Apr 5;1464(2):199-206.<br>
<br>
Yours ....ariel<br>
<br>
--------------------------------------------------------------------<br>
<font face="Arial, Helvetica" size=2>Fumio-</font> <br>
<br>
<font face="Arial, Helvetica" size=2>Partial specific volume of
octylglucoside is 0.859 (Reynolds & McCaslin (1985), Methods in
Enzymology, 117:41-53)</font> <br>
<br>
<font face="Arial, Helvetica" size=2>Partial specific volume of
decylmaltoside is 0.795. I determined this for my thesis work using
density measurments at several detergent concentrations using a
Mettler/Paar density meter (DMA 01 C).</font> <br>
<br>
<font face="Arial, Helvetica" size=2>Regards,</font> <br>
<br>
<font face="Arial, Helvetica" size=2>John Harlan</font> <br>
---------------------------------------------------------------------<br>
<br>
<br>
At 15:10 03/11/22 +0100, Lustig wrote:<br>
<br>
<blockquote type=cite class=cite cite>Dear John Harlan , Fumio and
colleagues,<br>
I'm not astonished that you =John report on a bit
different Vbar values as I have done.<br>
The deviation of detergent micelles densities stem from
several reasons.<br>
We have to understand that a detergent solution is mixture of underand over CMC.<br>
This equilibrium of particles may differ by concentrationand used buffer/water.<br>
In density-meters you need to know the realconcentration of micelles and this<br>
is quasi impossible for the Vbar determination, where you have tocross<br>
the under CMC range.<br>
In AUC you can determine the micelles density with schlieren and interference<br>
in densifiers between sedimentation and floatation, but thisdensities are hydrated once.<br>
with a water shell so they are 40-50% off.<br>
Different producers of detergents reports on different subunits fora micelle so<br>
also the density variegates.<br>
The reference of Shire (15 of the BBA paper I sent to Fumio) gives alsodifferent values<br>
as the Meth.of Enzymology.if not to trust in my own measurements.<br>
<br>
Yours....ariel</blockquote>
<x-sigsep><p></x-sigsep>
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Fumio Arisaka, Ph.D.<br>
Department of Biomolecular Engineering<br>
Graduate School of Bioscience and Biotechnology<br>
Tokyo Institute of Technology<br>
5249 Nagatsuta, Midori-ku<br>
Yokohama 226-8501 JAPAN<br>
Tel/Fax:+81-45-924-5713<br>
E-mail: farisaka@bio.titech.ac.jp<br>
URL
<a href="http://www.farisaka.bio.titech.ac.jp/" eudora="autourl">http</a>://www.farisaka.bio.titech<a href="http://www.farisaka.bio.titech.ac.jp/" eudora="autourl">.ac.jp/</a>$B!!!!(B<br>
$B!!!!!!(B
<a href="http://edpex104.bcasj.or.jp/pricps2004/" eudora="autourl">http</a>://edpex104.bcasj.or.jp<a href="http://edpex104.bcasj.or.jp/pricps2004/" eudora="autourl">/pricps2004/</a><br>
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