Macromolecules, co-solutes and solvents – A crucial interplay
Dr. Jens Smiatek (Institute for Computational Physics, University of Stuttgart)

The properties of the solvent in terms of chemical and physical interactions as well as the presence of co-solutes have important consequences for most biological and chemical processes and the behavior of the studied solute. Atomistic and mesoscopic Molecular Dynamics simulations pave a way towards a more detailed understanding of the underlying mechanisms. In this talk, recent results of computer simulations will be presented that illustrate the interplay between solvent and solutes on different scales.
In the first part of the talk, the impact of co-solutes like urea and hydroxyectoine on DPPC lipid bilayers and on the solvation properties of model spheres and antifreeze proteins will be discussed [1,2,3]. In addition, I will present the findings of atomistic Molecular Dynamics simulations with regard to stable configurations of DNA i-motifs and synthetic polyelectrolytes and their interactions with the local solvent shell [4,5,6]. Via free energy calculations, we are able to elucidate the solvent stabilized energetically most favorable conformations and to systematically analyze the ion condensation behavior. All our results indicate that the specific chemical nature of the solvent is important for a deeper understanding of most effects.
In the last part of the talk, I will also discuss the results of coupled mesoscopic Lattice-Boltzmann / Molecular Dynamics simulations with regard to the importance of hydrodynamic interactions as mediated by the solvent for grafted polyelectrolytes in confined geometries [7].

[1] J. Smiatek, R. K. Harishchandra, H.-J. Galla, A. Heuer, Biophys. Chem. 180-181, 102 (2013)
[2] J. Smiatek, J. Phys. Chem. B 118, 771 (2014)
[3] A. N. Krishnamoorthy, C. Holm, J. Smiatek, J. Phys. Chem. B, doi: 10.1021/jp507062r (2014)
[4] J. Smiatek, C. Chen, D. Liu, A. Heuer, J. Phys. Chem. B 115, 13788 (2011)
[5] J. Smiatek, A. Heuer, RSC Adv. 4, 17110 (2014)
[6] J. Smiatek, A. Wohlfarth, C. Holm, New J. Phys. 16, 025001 (2014)
[7] O. A. Hickey, C. Holm, J. Smiatek, J. Chem. Phys. 140, 164904 (2014)