Interconverting conformations of variants of the human amyloidogenic protein β2-microglobulin quantitatively characterized by dynamic capillary electrophoresis and computer simulation

Capillary electrophoretic separation profiles of cleaved variants of beta(2)-microglobulin (beta(2)m) reflect the conformational equilibria existing in solutions of these proteins. The characterization of these equilibria is of interest since beta(2)m is responsible for amyloid formation in dialysis-related amyloidosis and thus is able to attain alternative conformations that lead to irreversible aggregation and precipitation. In this study, we quantitate the increased conformational instability of cleaved, beta(2)m by extracting rate constants and activation energies by simulating the experimental data using a unified theory for dynamic chromatography and dynamic electrophoresis. The results are correlated with the outcome of independent experiments based on mass spectrometric measurement of H/D exchange. This study illustrates that dynamic capillary electrophoresis is suitable for the investigation of the interconversion of protein conformations of amyloidogenic molecules and is not only restricted to ideal model compounds.