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Ion Specific Hofmeister Effects on Peptides and Proteins
Hladílková, Jana ; Jungwirth, Pavel (advisor) ; Ettrich, Rüdiger (referee) ; Horinek, Dominik (referee)
Title: Ion Specific Hofmeister Effects on Peptides and Proteins Author: Ing. Jana Hladílková Department: Physical and Macromolecular Chemistry Advisor: Prof. Pavel Jungwirth, DSc., IOCB AS CR Advisor's email address: pavel.jungwirth@uochb.cas.cz Abstract: Classical molecular dynamics simulations in combination with advanced methods of analysis were used to shed light on missing parts of our molecular understanding of the Hofmeister series. In tandem with various experimental techniques, real proteins as well as model systems were investigated in aqueous salt solutions in order to identify and quantify ion-protein interactions either leading or not leading to the canonical cationic and anionic Hofmeister ordering. The potassium cation was found to significantly enhance the BHMT enzymatic activity in contrast to the rest of the common monovalent cations. In the quest to rationalize this behavior, a key potassium binding site in the vicinity of the active site was discovered and described. Moreover, the exceptionally strong effect of K+ on the enzymatic activity was explained by hydration properties of the cations within the limited space of the active site in interplay with their attraction to the nearby negatively charged residues. By contrast, only a small and indirect influence, which follows the cationic...
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Mobilization of neutral compounds by inorganic and small organic ions in capillary electrophoresis
Křížek, T. ; Martínková, E. ; Kubíčková, A. ; Hladílková, Jana ; Coufal, P. ; Heyda, J. ; Jungwirth, Pavel
The present study shows that neutral low-molecular-mass compounds that are presumed to possess zero electrophoretic mobility and are thus used as markers of electroosmotic flow in capillary electrophoresis can acquire electrophoretic mobility due to ion-specific interactions with constituents of background electrolyte. Therefore, these neutral markers, such as thiourea or dimethyl sulfoxide, can be separated in electric field and their migration order can vary depending on background electrolyte composition. This observation has some important implications for analytical and physico-chemical measurements using capillary electrophoresis because the choice of the marker-background electrolyte combination can influence the results of the measurement.
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