Capillary electrophoresis for thermodynamic and kinetic studies of peptidyl-proline isomerization by the theoretical plate height model.

The theoretical plate height model, extended to include reactive CE, is used to calculate equilibrium constants and rate constants for the reversible, first-order isomerization of proline dipeptides. This model is consistent with chromatographic theory and enables calculation of equilibrium constants from velocity and calculation of rate constants from plate height. Thermodynamic and kinetic parameters for isomerization of Ala-Pro and Phe-Pro are calculated by using the plate height model, and are shown to be in good agreement with literature values. Additionally, the efficacy of the plate height model is compared to ChromWin, an existing simulation method for calculating rate constants from zone profiles. It is shown that ChromWin and the plate height model are complementary methods. ChromWin is best used for calculating rate constants for reactions that are far from steady state, where the zone profiles exhibit plateau formation. On the other hand, the plate height model is best used for calculating rate constants for reactions that are at or near steady state, where the zone profiles exhibit a single zone containing both reacting species.