Sedimentation and Gel-Permeation Chromatography of Associating-Dissociating Macromolecules
Some years ago we reported that in the many applications of zone electrophoresis to biological problems it is imperative that cognizance be taken of the fact that multiple zones need not necessarily indicate inherent heterogeneity. Thus, both theoretical calculations (Cann and Goad, 1965) and experimentation (Cann, 1966) revealed that, under appropriate conditions, a single macromolecule interacting reversibly with an uncharged constituent of the solvent medium can give two zones despite instantaneous establishment of equilibrium. Moreover, a single macromolecule, which isomerizes reversibly at rates comparable to the rate of electrophoretic separation of the isomers, can give three zones. Accordingly, it was emphasized that unequivocal proof of inherent heterogeneity is afforded only by isolation of the various components. Since that time, we have extended these concepts to include the sedimentation and gel-permeation chromatography of ligandmediated associating—dissociating macromolecules and some representative kinetically controlled interactions. A review of these advances and their implications for the separation of proteins and the characterization of biologically important interactions is given below.
KeywordsSedimentation Pattern Zone Sedimentation Sedimentation Behavior Spreading Zone Carbamyl Phosphate
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