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<DIV>I'm running AUC experiments with a membrane protein.</DIV>
<DIV> </DIV>
<DIV>The detergent I am using has a relatively high value for vbar = 0.9747 (Maslennikov et al 2007)</DIV>
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<DIV>I am trying to achieve a situation where the detergent contribution to the PDC buoyant mass is negligible (when the buffer density ~ matches the detergent density).</DIV>
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<DIV>Buffer density = 1.00585<BR>Detergent vbar = 0.9747 </DIV>
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<DIV>Using the equation: </DIV>
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<DIV>p = 1/vbar-det</DIV>
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<DIV>Detergent density = 1 / 0.9747 = 1.0258567</DIV>
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<DIV>Is it valid to (a) increase the percentage of detergent in the buffer to increase the buffer density to match the detergent density (while remaining below the cMc)?, (b) add other non-interacting components into the buffer (d2o / h2o, sucrose, etc), and use e.g. SedNterp to calculate the correct proportions of these components to achieve the desired buffer density?</DIV>
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<DIV>If the buffer and detergent densities are matched in this way, doesn't a velocity experiment provide accurate enough mass, without running equilibrium experiments?</DIV>
<DIV><BR>And if the detergent does not absorb at 280 nm, won't absorbance measurements provide the protein-only mass of the protein-detergent complex? </DIV>
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<DIV>Many Thanks</DIV>
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<DIV>Mark</DIV>
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<DIV> </DIV>
<DIV>~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~<BR>Dr Mark Agacan, Scientific Officer for the Division of Biological Chemistry and Drug Discovery,<BR>Wellcome Trust Biocentre, College of Life Sciences, University of Dundee, Dundee, DD1 5EH <BR>Tel: +44 1382 386095 Fax: +44 1382 345764 Mobile: 07525 451 117<BR>~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~</DIV>
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