engleski

Microscopic Insights of the Molecular Associations in Liquid Systems

Classical molecular dynamic simulations offer an insight into the microscopic evolution of the structural organisation, which is not easily accessible by experiments. The critical issue is the choice of the effective potentials or force field models, as well as the choice of the system size and the time scale of the simulations. We address these questions in analyzing the associations in several liquid systems by means of statistical mechanics. In this presentation, we show two distinct examples: the domain formation in the molecular liquid mixtures [1] and the association of the antimicrobial peptide with the membrane [2]. In the former case, the aim is to describe changes in molecular associations, which depend on the molar ratio of the components. We use the microscopic view obtained from the simulation data and connect this with the experimental, mostly thermodynamic results. The evolution of the structure is described by static properties such as pair correlation functions and atom-atom structure factors. The heterogeneity in the structural organisation is then connected with the behaviour of excess properties, Kirkwood-Buff integrals, and diffusion coefficients. In the latter case, we seek to elucidate the behaviour of antimicrobial peptides. These peptides are part of the innate immune system in all organisms, which act against pathogens by disrupting the integrity of their membrane. We show the simulation results for peptides in different solutions and within the membrane. By combining the numerical results with the biological and biophysical measurement of the peptide structure and activity we aim to understand their mechanism of action. References: [1] T. Rončević, G. Gajski, N. Ilić, I. Goić-Barišić, M. Tonkić, L. Zoranić, J. Simunić, M. Benincasa, M. Mijaković, A. Tossi and D. Juretić, PGLa-H tandem-repeat peptides active against multidrug resistant clinical bacterial isolates. BBA Biomembranes, 1859 (2), (2017), 228-237 [2] M. Požar, J.B. Seguier, J. Guerche, R. Mazighi, L. Zoranić, M. Mijaković, B. Kežić-Lovrinčević, F. Sokolić and A. Perera, Simple and complex disorder in binary mixtures with benzene as a common solvent. Phys. Chem. Chem. Phys., 17, (2015), 9885-9898

liquid mixtures, molecular dynamics, antimicrobial peptides

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