Ion Specific Hofmeister Effects on Peptides and Proteins

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..