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<DIV>Sorry for being late in sending this email - I misplaced my ET Adams folder & wanted to be sure I knew what moments were discussed in his papers. I discuss these papers in my 2000 weight average review. These papers present the theory of using sn, sw and sz for self associating systems. Historically they fall into the category of graphical techniques that dominated the analysis of data in the 70's, especially equilibrium data. They are probably most useful for model building and parameter estimation but on a system by system basis they should give the same answers as direct boundary fitting.</DIV>
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<DIV>I would like to revive a suggestion made by Allen Minton last year that we create an Online Library of old papers. I am sure there are legal issues, but for example my library does not have the volumes these papers came from, I had to use interlibrary loan, and the 1973 paper doesn't even show up in a PubMed search. Walter has set up a classic papers folder on RASMB, the format of which is not yet decided, although it is searchable through the RASMB search engine.</DIV>
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<DIV><A href="http://rasmb.bbri.org/rasmb/classic_literature/">http://rasmb.bbri.org/rasmb/classic_literature/</A></DIV>
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<DIV>Weirich CA, Adams ET Jr & Barlow GH (1973) Bioiphys Chem 1, 35-45 (1973) Sedimentation coefficients of self-associating species. I. Basic Theory</DIV>
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<DIV>Abstract: Under the same solution conditions, the apparent weight average sedimentation coefficient, swa, and some quantities obtained from it can be combined with the equilibrium constant or constants , Ki, and the monomer concentration, c1, obtained from sedimentation equilibrium, light scattering or osmotic pressure experiments on the same self-associating solute, so that the individual sedimentation ceoefficients , si, of the self-associating species, and also the hydrodynamic concentration dependence parameter, g or gs, can be evaluated. Using two different models for the hydrodynamic concentration parameter, four different methods are presented for the evaluation of si's. Methods for evaluating g or gs, once the si's are known, are presented. A method for obtaining the number average sedimentation coefficient, Sn, and its application to self-association is presented. Methods are shown for the evaluation of z average properties, Xzc, as well as number average properties, XNc, of a self-associating solute from its weight average properties, Xwc.</DIV>
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<DIV><BR>Beckerdite JM, Weirich CA, Adams ET Jr, Barlow GH. Biophys Chem. 1983 Apr;17(3):203-10. Sedimentation coefficients of self-associating species. II. Tests with a simulated example and with beta-lactoglobulin A.</DIV>
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<DIV>Abstract: If sedimentation equilibrium and sedimentation velocity experiments are performed on a self-associating solute under the same solution conditions, it is possible to evaluate the sedimentation coefficients (si) of the self-associating species and the usual concentration dependence parameter (g or gs). We have tested some of these methods with simulated examples. A more critical test is to use real data. Sedimentation equilibrium experiments with beta-lactoglobulin A at 20 degrees C in 0.2 M glycine buffer (pH 2.46) indicated that a nonideal monomer-dimer association was present. Sedimentation velocity experiments were performed on beta-lactoglobulin A under the same conditions. Using data from both sets of experiments we were able to evaluate s1, s2, g and gs using two different models for swa, the apparent weight average sedimentation coefficient. The empirical model for swa developed by Weirich et al. [1] gave better variance than did the model for swa developed by Gilbert and his co-workers [2-5]. Using a simulated monomer-dimer association mimicking a system having higher sedimentation coefficients than beta-lactoglobulin A did, we were able to show that one could not obtain s2 from tangents to the plot of 1/swa vs. c in the high concentration region. The methods developed here for sedimentation coefficients can be applied to other experiments in which a weight average property (or its apparent value) of a self-associating solute is measured, provided the appropriate thermodynamic experiments are done under the same solution conditions. <BR><BR></DIV>
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<DIV>-------------------------------------------------------------------<BR> Dr. John J. "Jack" Correia<BR> Department of Biochemistry<BR> University of Mississippi Medical Center<BR> 2500 North State Street<BR> Jackson, MS 39216<BR> (601) 984-1522 <BR> fax (601) 984-1501 <BR> email address: <A href="mailto:jcorreia@biochem.umsmed.edu">jcorreia@biochem.umsmed.edu</A> <BR> homepage location: <A href="http://biochemistry.umc.edu/correia.html">http://biochemistry.umc.edu/correia.html</A><BR> dept homepage location: <A href="http://biochemistry.umc.edu/">http://biochemistry.umc.edu/</A><BR>-------------------------------------------------------------------<BR> <BR> <BR></DIV></BODY></HTML>