Zusammenfassung
Investigations of monomeric and micellar detergents, protein-detergent complexes, as well as native and denatured proteins by means of various physicochemical techniques yield a wide range of molecular characteristics of the components under analysis. Varying the experimental conditions (e.g., the concentration of solutes or the ionic strength of the medium) allows the mass, gross structure, and ...
Zusammenfassung
Investigations of monomeric and micellar detergents, protein-detergent complexes, as well as native and denatured proteins by means of various physicochemical techniques yield a wide range of molecular characteristics of the components under analysis. Varying the experimental conditions (e.g., the concentration of solutes or the ionic strength of the medium) allows the mass, gross structure, and structural details of the macromolecular components to be determined. However, several modifications of the conventional techniques and evaluation procedures have to be applied in order to analyze multicomponent systems consisting of several low-molecular, micellar, and macromolecular components in an appropriate way. In the case of weakly absorbing detergents, labeling of the detergent micelles by specific dyes is required. Evidently, impurities and lack of homogeneity of many detergents may severely disturb the precise evaluation of the experiments; both necessitate a series of precautions in order to avoid misinterpretations. Analytical ultra-centrifugation, size-exclusion chromatography, together with viscometry and densimetry, yield molar masses, mass distributions, and the overall structure of micellar and macromolecular molecules. In contrast, spectroscopic methods (UV absorption, fluorescence emission and excitation, far- and near-UV circular dichroism) monitor only local details of detergent-induced changes in the environment of aromatic residues. The technique of sodium dodecyl sulfate-polyacrylamide gel electrophoresis is routinely applied in biochemical work in order to establish molar masses of simple and conjugated proteins. To study the binding behavior of detergents to proteins in quantitative terms, however, techniques (e.g., equilibrium centrifugation, electrophoresis and chromatography) involving detergent concentrations have to be used.
Altmetric