Determination of the microenvironment-pH and charge and size characteristics of amino acids through their electrophoretic mobilities determined by CZE

Electrokinetic behavior of a pH-regulated, zwitterionic nanocylinder in a cylindrical nanopore filled with multiple ionic species

Recent advances in fabrication techniques make nano-sized pores as promising platforms for both detection and sequencing of individual biopolymers such as DNA. To simulate the electrokinetic behavior of a particle in this case, we consider the electrophoresis of a soft nanocylinder comprising a rigid core and a pH-regulated, zwitterionic polyelectrolyte layer along the axis of a rigid cylindrical nanopore. Extending the conventional electrophoresis analysis, where the liquid phase contains only one kind each of cations and anions, we assume that it contains multiple ionic species, as is usually the case in practice. The key parameters are examined for their influences on the electrokinetic behavior of a particle. These include pH, the thickness of the polyelectrolyte layer and the density of its functional groups, and the pore size. The results gathered provide necessary information for the design of an electrokinetic apparatus.

Hydration, charge, size, and shape characteristics of peptides from their CZE analyses

A CZE model is presented for peptide characterization on the basis of well-established physicochemical equations. The effective mobility is used as basic data in the model to estimate relevant peptide properties such as, for instance, hydration, net and total electrical charge numbers, hydrodynamic size and shape, particle average orientation, and pH-microenvironment from the charge regulation phenomenon. Therefore 102 experimental effective mobilities of different peptides are studied and discussed in relation to previous work. An equation for the estimation of peptide hydration as a function of ionizing, polar, and non-polar amino acid residues is included in the model. It is also shown that the shape-orientation factor of peptides may be either lower or higher than one, and its value depends on a complex interplay among total charge number, molar mass, hydration, and amino acid sequence.