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At 12:20 PM 4/8/2008, you wrote:<br><br>
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<font size=2 color="#0000FF">(3) The regulatory agencies would
indeed like to know the exact distribution of oligomers, both reversible
and irreversible, in the product vial, even for products at 100+ mg/mL.
Unfortunately they don't always understand that this may be technically
impossible with current technology and current theoretical understanding
of the strong non-ideality effects that may be
present.</font></blockquote><br>
We've developed some approximate methods for interpretation of static
light scattering, sedimentation equilibrium, and osmotic pressure of
highly concentrated (> 100 mg/ml) protein solutions containing
multiple macrosolute species (including both reversibly and irreversibly
formed oligomers). We know the conditions under which the
approximations in the model ought to be valid, and the methods seem to
work pretty well when applied to data obtained under those
conditions. Analyses of data obtained by different methods from the
same protein yield internally consistent results. If you are
interested, check out the following publications:<br><br>
<font face="Arial, Helvetica">Minton AP. 2008. Effective hard
particle model for the osmotic pressure of highly concentrated binary
protein solutions. Biophys. J 94: L57-59.<br><br>
Jiménez M, Rivas G, Minton AP. 2007. Quantitative characterization of
weak self-association in concentrated solutions of immunoglobulin G via
measurement of sedimentation equilibrium and osmotic pressure.
Biochemistry 45: 13356-60.<br><br>
Minton AP. 2007. Static light scattering from concentrated protein
solutions. I. General theory for protein mixtures and application
to self-associating proteins. Biophys J 93: 1321-8.<br><br>
Minton AP. 2007. The effective hard particle model provides a simple,
robust and broadly applicable description of nonideal behavior in
concentrated solutions of bovine serum albumin and other non-associating
proteins. J Pharm Sci 96: 3466-69.<br><br>
Zorrilla S, Jimenez M, Lillo P, Rivas G, Minton AP. 2004. Sedimentation
equilibrium in a solution containing an arbitrary number of solute
species at arbitrary concentrations: theory and application to
concentrated solutions of ribonuclease. Biophys Chem 108:89-100.<br><br>
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