title: Precise, fast and flexible determination of protein interactions by affinity capillary electrophoresis. Part 2: cations.
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.
authors.affiliation: Institute of Medicinal and Pharmaceutical Chemistry, TU Braunschweig, Braunschweig, Germany.
authors.forename: Sabine
authors.initials: S
authors.lastname: Redweik
authors.forename: Claudia
authors.initials: C
authors.lastname: Cianciulli
authors.forename: Masakazu
authors.initials: M
authors.lastname: Hara
authors.forename: Yuanhong
authors.initials: Y
authors.lastname: Xu
authors.forename: Hermann
authors.initials: H
authors.lastname: Wätzig
mesh_terms: D000818:Animals; D002412:Cations / Q000737:chemistry; D002417:Cattle; D019075:Electrophoresis, Capillary / Q000379:methods*; D008670:Metals / Q000737:chemistry / Q000378:metabolism; D008956:Models, Chemical; D004364:Pharmaceutical Preparations / Q000737:chemistry / Q000378:metabolism; D011485:Protein Binding; D011506:Proteins / Q000032:analysis* / Q000737:chemistry / Q000378:metabolism; D015203:Reproducibility of Results; D012710:Serum Albumin, Bovine / Q000032:analysis / Q000737:chemistry / Q000378:metabolism
chemical_list: D002412:Cations; D008670:Metals; D004364:Pharmaceutical Preparations; D011506:Proteins; D012710:Serum Albumin, Bovine