Dokument-ID Dokumenttyp Autoren/innen Persönliche Herausgeber/innen Haupttitel Abstract Auflage Verlagsort Verlag Herausgeber (Institution) Erscheinungsjahr Titel des übergeordneten Werkes Jahrgang/Band ISBN Veranstaltung Veranstaltungsort Beginndatum der Veranstaltung Enddatum der Veranstaltung Ausgabe/Heft Erste Seite Letzte Seite URN DOI Lizenz Datum der Freischaltung OPUS4-37676 Zeitschriftenartikel Hahn, Marc Benjamin; Uhlig, F.; Solomun, Tihomir; Smiatek, J.; Sturm, Heinz Combined influence of ectoine and salt: spectroscopic and numerical evidence for compensating effects of aqueous solutions Ectoine is an important osmolyte, which allows microorganisms to survive in extreme environmental salinity. The hygroscopic effects of ectoine in pure water can be explained by a strong water binding behavior whereas a study on the effects of ectoine in salty solution is yet missing. We provide Raman spectroscopic evidence that the influence of ectoine and NaCl are opposing and completely independent of each other. The effect can be explained by the formation of strongly hydrogen-bonded water molecules around ectoine which compensate the influence of the salt on the water dynamics. The mechanism is corroborated by first principles calculations and broadens our understanding of zwitterionic osmolytes in aqueous solution. Our findings allow us to provide a possible explanation for the relatively high osmolyte concentrations in halotolerant bacteria. UK Royal Society of Chemistry Royal Society of Chemistry 2016 Physical Chemistry Chemical Physics 18 41 28398 28402 urn:nbn:de:kobv:b43-376761 10.1039/c6cp05417j http://creativecommons.org/licenses/by/3.0/de/deed.de 2016-10-24 OPUS4-50985 Zeitschriftenartikel Solomun, Tihomir; Hahn, Marc Benjamin; Smiatek, J. Raman spectroscopic signature of ectoine conformations in bulk solution and crystalline state Recent crystallographic results revealed conformational changes of zwitterionic ectoine upon hydration. By means of confocal Raman spectroscopy and density functional theory calculations, we present a detailed study of this transformation process as part of a Fermi resonance analysis. The corresponding findings highlight that all resonant couplings are lifted upon exposure to water vapor as a consequence of molecular binding processes. The importance of the involved molecular groups for water binding and conformational changes upon hydration is discussed. Our approach further Shows that the underlying rapid process can be reversed by carbon dioxide saturated atmospheres. For the first time, we also confirm that the conformational state of ectoine in aqueous bulk solution coincides with crystalline ectoine in its dihydrate state, thereby highlighting the important role of a few bound water molecules. Weinheim Wiley-VCH 2020 ChemPhysChem 21 17 1945 1950 urn:nbn:de:kobv:b43-509855 10.1002/cphc.202000457 https://creativecommons.org/licenses/by/4.0/deed.de 2020-07-08 OPUS4-35800 Zeitschriftenartikel Hahn, Marc Benjamin; Solomun, Tihomir; Wellhausen, Robert; Herrmann, S; Seitz, H; Meyer, Susann; Kunte, Hans-Jörg; Zeman, J.; Uhlig, F; Smiatek, J; Sturm, Heinz Influence of the Compatible Solute Ectoine on the Local Water Structure: Implications for the Binding of the Protein G5P to DNA Microorganisms accumulate molar concentrations of compatible solutes like ectoine to prevent proteins from denaturation. Direct structural or spectroscopic information on the mechanism and about the hydration shell around ectoine are scarce. We combined surface plasmon resonance (SPR), confocal Raman spectroscopy, molecular dynamics simulations, and density functional theory (DFT) calculations to study the local hydration shell around ectoine and its influence on the binding of a gene-S-protein (G5P) to a single-stranded DNA (dT(25)). Due to the very high hygroscopicity of ectoine, it was possible to analyze the highly stable hydration shell by confocal Raman spectroscopy. Corresponding molecular dynamics simulation results revealed a significant change of the water dielectric constant in the presence of a high molar ectoine concentration as compared to pure water. The SPR data showed that the amount of protein bound to DNA decreases in the presence of ectoine, and hence, the protein-DNA dissociation constant increases in a concentration-dependent manner. Concomitantly, the Raman spectra in terms of the amide I region revealed large changes in the protein secondary structure. Our results indicate that ectoine strongly affects the molecular recognition between the protein and the oligonudeotide, which has important consequences for osmotic regulation mechanisms. 2015 The journal of physical chemistry / B 119 49 15212 15220 10.1021/acs.jpcb.5b09506 2016-04-21 OPUS4-46327 Zeitschriftenartikel Oprzeska-Zingrebe, E. A.; Meyer, Susann; Roloff, Alexander; Kunte, Hans-Jörg; Smiatek, J. Influence of compatible solute ectoine on distinct DNA structures: thermodynamic insights into molecular binding mechanisms and destabilization effects In nature, the cellular environment of DNA includes not only water and ions, but also other components and co-solutes, which can exert both stabilizing and destabilizing effects on particular oligonucleotide conformations. Among them, ectoine, known as an important osmoprotectant organic co-solute in a broad range of pharmaceutical products, turns out to be of particular relevance. In this article, we study the influence of ectoine on a short single-stranded DNA fragment and on double-stranded helical B-DNA in aqueous solution by means of atomistic molecular dynamics (MD) simulations in combination with molecular theories of solution. Our results demonstrate a conformation-dependent binding behavior of ectoine, which favors the unfolded state of DNA by a combination of electrostatic and dispersion interactions. In conjunction with the Kirkwood-Buff theory, we introduce a simple Framework to compute the influence of ectoine on the DNA melting temperature. Our findings reveal a significant linear decrease of the melting temperature with increasing ectoine concentration, which is found to be in qualitative agreement with results from denaturation experiments. The outcomes of our Computer simulations provide a detailed mechanistic rationale for the surprising destabilizing influence of ectoine on distinct DNA structures. Royal Society of Chemistry 2018 Phys.Chem.Chem.Phys. 20 40 25861 25874 10.1039/c8cp03543a 2018-10-19