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<p class="MsoNormal">Hello members!<o:p></o:p></p>
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<p class="MsoNormal">We have a project where we are trying to extract association constants from sedimentation equilibrium data of a self-associating mAb. We are noticing a lot of variability in the association constants fit to between concentrations and even
between replicates of the same concentration. My question is, is this expected? If not, what are some possible reasons it could be happening and what can I do to resolve it?<o:p></o:p></p>
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<p class="MsoNormal">I’ll give more information in case it is relevant. We are using Beckman 6-sector cells and absorbance optics at 280 nm. Our initial guess as to rotor speed was a little high and gave sigma’s between 4 and 5. In some sectors there was a
mismatch between sample and reference, but nothing in the buffer absorbs at 280 nm. In the fit we are using Heteroanalysis with a monomer-nmer model and constraining the molecular weight and stoichiometry.<o:p></o:p></p>
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<p class="MsoNormal">We had a relatively new user load the cells, could cross contamination between reference and sample combined with a mismatched meniscus cause this?</p>
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<p class="MsoNormal">Thanks in advance for your feedback!<o:p></o:p></p>
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<div style="margin:0px"><font face="Times New Roman,serif" size="3"><span style="font-size:12pt"><font face="Tahoma,sans-serif" size="2"><span style="font-size:10pt">- Ronald Toth</span></font></span></font></div>
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<div style="margin:0px"><font face="Times New Roman,serif" size="3"><span style="font-size:12pt"><font face="Tahoma,sans-serif" size="2"><span style="font-size:10pt">Post Doctoral Researcher</span></font></span></font></div>
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<div style="margin:0px"><font face="Times New Roman,serif" size="3"><span style="font-size:12pt"><font face="Tahoma,sans-serif" size="2"><span style="font-size:10pt">Macromolecule and Vaccine Stabilization Center</span></font></span></font></div>
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<div style="margin:0px"><font face="Times New Roman,serif" size="3"><span style="font-size:12pt"><font face="Tahoma,sans-serif" size="2"><span style="font-size:10pt">University of Kansas</span></font></span></font></div>
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