Dresden 2014 – scientific programme

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BP: Fachverband Biologische Physik

BP 6: Posters: Membranes and vesicles

BP 6.11: Poster

Monday, March 31, 2014, 17:30–19:30, P3

Strongly hydrogen bonded water in the hydrophobic tail of lipid bilayers — •Marie Tritschel and Stephan Gekle — Biofluid Simulation and Modeling, Universität Bayreuth

Recent vibrational sum frequency experiments [1] detected strongly hydrogen bonded water molecules at lipid interfaces which were tentatively attributed to hydrogen bonds between water molecules and the phosphate group. However, similar features were also detected in lipids without a phosphate group such as DPTAP.

Using molecular dynamics simulation we show that in addition to water phosphate bonds there exists a sizeable amount of water molecules strongly hydrogen bonded to the carbonyl group in the hydrophobic tail of DPPC. The interaction energy of these bonds is approximately twice as high as in bulk water. Since similar carbonyl groups are also present in DPTAP this may explain the experimental observations.

Finally, we show that the interaction energy of a hydrogen bond is similar when the second binding partner is either water or an atom from a neighbouring lipid, whereas it is higher when the water shares its two hydrogen bonds with the same lipid.

[1] M. Bonn, H. J. Bakker, A. Ghosh, S. Yamamoto, M. Sovago, and R. K. Campen; 132 J. Am. Chem. Soc. [2010], 14971