Light-scattering from detergent-complexed biological macromolecules.
A theory is described for Rayleigh light-scattering from solutions of detergent-complexed macromolecules applicable to measurements carried out under conditions of Donnan equilibrium. The theory shows that when scattering measurements are made on detergent-solubilized macromolecules in the presence of detergent micelles the apparent Mr is dependent on the extent of detergent binding and effective charge on the detergent-macromolecule complex and the micellar charge and aggregation number. Equations are given for the apparent Mr of the macromolecule under limiting conditions of high salt and low salt concentration. Low-angle laser-light-scattering measurements were made on lysozyme complexed with sodium n-dodecyl sulphate both in the absence and in the presence of detergent micelles. These experimentally obtained data were used in conjunction with the detergent-binding isotherm to test the theory at high ionic strength. Light-scattering measurements were also made on detergent-saturated complexes as a function of ionic strength and pH. The results are in reasonable accord with both the qualitative and the quantitative predictions of the theory.
D008027:Light; D046911:Macromolecular Substances; D008956:Models, Chemical; D009113:Muramidase; D009994:Osmolar Concentration; D011485:Protein Binding; D012542:Scattering, Radiation; D012967:Sodium Dodecyl Sulfate; D014461:Ultracentrifugation
D046911:Macromolecular Substances; D012967:Sodium Dodecyl Sulfate; D009113:Muramidase