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Updated: May 10, 2026

Highly Sensitive and Quantitative Detection of Proteins and Their Isoforms by Capillary Isoelectric Focusing Method
Published on: September 19, 2018
Precise, fast and flexible determination of protein interactions by affinity capillary electrophoresis. Part 2:
Sabine Redweik1, Claudia Cianciulli, Masakazu Hara
1Institute of Medicinal and Pharmaceutical Chemistry, TU Braunschweig, Braunschweig, Germany.
Abstract:
The influence of various cations as metal ions (barium, calcium, copper, magnesia, manganese, and nickel), pharmaceuticals (ephedrine, ethambutol, pilocarpine, and pirenzepine), arginine, and guanidine has been tested on BSA, β-lactoglobulin, and ovalbumin. Influences on proteins regarding changes in size, charge, or mass were of particular interest. ACE proved to be a suitable method to investigate these effects. ACE is able to observe slight but significant changes on proteins due to the excellent precision of the measurements. Therefore, some unexpected behaviors of protein-ligand interactions were found. The protein charge becomes more negative under metal ion influence and some pharmaceutical cations. Probably metal ions bound to the proteins form additional complexes with anions from the surrounding solution. Furthermore, already bound cations could be displaced at the protein surface. Both effects would change the overall charge of the ligand-protein complexes. In all studied cases, multiple-binding stoichiometries have been observed.
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