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Hi Prasad-<br>
To a reasonable first approximation, vbar is the inverse of the density of protein (~1.4 g/ml), and does not change with size. If you sediment at very low speeds, you may be able to see the boundary going down the cell in buffer. You also may wish to increase
the solvent viscosity using, for example, gycerol to slow down the sedimentation. The sedimentation coefficient will decrease as 1/viscosity, which will allow you to get more scans before the protein aggregates (micelles, perhaps?) pellet. If there is concern
that the glycerol is affecting the aggregation, you can repeat the experiment at a few glycerol concentration, correct the data for the viscosity/density of the solvent back to s20,w and see if the g(s) distributions change appreciably.<br>
What problems are you having with the lipoprotein? If you are seeing aggregation, you may need to add a detergent to 'cover' the lipid tails. Which detergent to use becomes trial and error black magic... unless someone has experience with your protein.
<br>
Best wishes,<br>
Tom<br>
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<div style="direction: ltr;" id="divRpF372649"><font face="Tahoma" size="2" color="#000000"><b>From:</b> RASMB [rasmb-bounces@list.rasmb.org] on behalf of Prasad Satyamurthy [psatyamurthy@wockhardt.com]<br>
<b>Sent:</b> Friday, December 05, 2014 1:49 AM<br>
<b>To:</b> rasmb@rasmb.org<br>
<b>Subject:</b> [RASMB] Problems in analysis of proteins using analytical ultracentrifugation<br>
</font><br>
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<p class="MsoNormal"><font face="Arial" size="2"><span style="font-size:10.0pt; font-family:Arial">Dear All,</span></font></p>
<p class="MsoNormal"><font face="Arial" size="2"><span style="font-size:10.0pt; font-family:Arial"> I have couple of problems in the analysis my proteins using analytical ultracentrifugation.
</span></font></p>
<p class="MsoNormal"><font face="Arial" size="2"><span style="font-size:10.0pt; font-family:Arial">First one is that I am trying to analyse the association state of my protein complex that is formed in between two proteins that associate to form crystals in
buffer solutions. These crystals are about a few microns in size. So it is possible to study the association state of such big size particles using analytical ultracentrifugation. Also I do not know how to calculate the v bar of bigger size particles of about
500 nm is it independent of size? </span></font></p>
<p class="MsoNormal"><font face="Arial" size="2"><span style="font-size:10.0pt; font-family:Arial"> </span></font></p>
<p class="MsoNormal"><font face="Arial" size="2"><span style="font-size:10.0pt; font-family:Arial">Second problem that I was having was when I was analysing a lipoprotein (protein having a hydrophobic lipid tail attached to it) does any one have any idea how
to analyse such samples ? </span></font></p>
<p class="MsoNormal"><font face="Arial" size="2"><span style="font-size:10.0pt; font-family:Arial"> </span></font></p>
<p class="MsoNormal"><font face="Arial" size="2"><span style="font-size:10.0pt; font-family:Arial">Any opinion or suggestion regarding the above problems that I am facing would be of great help to me. </span></font></p>
<p class="MsoNormal"><font face="Arial" size="2"><span style="font-size:10.0pt; font-family:Arial"> </span></font></p>
<p class="MsoAutoSig"><font face="Times New Roman" size="3"><span style="font-size:12.0pt">Thanks
</span></font></p>
<p class="MsoAutoSig"><font face="Times New Roman" size="3"><span style="font-size:12.0pt"> </span></font></p>
<p class="MsoAutoSig"><font face="Times New Roman" size="3"><span style="font-size:12.0pt">Prasad Satyamurthy</span></font>
</p>
<p class="MsoAutoSig"><font face="Times New Roman" size="3"><span style="font-size:12.0pt">Genomics and Biotechnology
</span></font></p>
<p class="MsoAutoSig"><font face="Times New Roman" size="3"><span style="font-size:12.0pt">D4 Chikalthana Aurangabad</span></font></p>
<p class="MsoAutoSig"><font face="Times New Roman" size="3"><span style="font-size:12.0pt">Email: psatyamurthy@wockhardt.com
</span></font></p>
<p class="MsoNormal"><font face="Times New Roman" size="3"><span style="font-size:12.0pt"> </span></font></p>
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