SKM 2023 – scientific programme

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BP: Fachverband Biologische Physik

BP 3: Computational Biophysics I

BP 3.10: Talk

Monday, March 27, 2023, 12:15–12:30, BAR 0106

MD simulations of n-alkanes in a phospholipid bilayer: CHARMM36 vs. Slipids — •Anika Wurl and Tiago Ferreira — Institute of Physics, Martin-Luther Universität Halle-Wittenberg

The incorporation of n-alkanes into phospholipid bilayers is a convenient starting point for studying the molecular behavior of linear, (purely) hydrophobic molecules in lipid membranes. Here, we perform atomistic molecular dynamics simulations using two state-of-the-art lipid force fields, CHARMM36 [1] and Slipids [2], to systematically investigate how the miscibility of n-alkanes in dipalmitoylphosphatidylcholine (DPPC) bilayers depends on alkane chain length. The two force fields show a distinct behavior: Slipids simulations predict an effect of chain length on miscibility, while for CHARMM36 simulations this is not the case for the alkanes studied. A comparison with ²H NMR spectra shows that the accuracy of the two force fields is dependent on alkane length. CHARMM36 performs well for the shorter chains, while Slipids models the longer alkanes better. Slipids chains are more flexible, due to reduced electrostatic 1-4 interactions compared to CHARMM36. By scaling these 1-4 interactions, CHARMM36 can be adapted to model longer alkanes and lipid acyl tails better. The presented results are of general interest for future studies of other long and flexible hydrophobic molecules inside lipid membrane environments, and show that n-alkane/lipid mixtures should be taken into account for optimization of force fields designed to model lipid membranes. [1] Jämbeck et al.; J Phys Chem B 2012, 116, 3164-3179 [2] Klauda et al.; J Phys Chem B 2010, 114, 7830-7843