The next seminar “Modelling of materials – theory, model reduction and efficient numerical methods” will take place next Monday (April 8, 2019) in the room K2 from 9:00 till 10:30. The talk will be given by Christoph Allolio. Please see the details below.
Speaker: Christoph Allolio
Title: The Interplay of Membrane Curvature Elasticity, Charge and Specific Molecular Interactions
Abstract: Molecular species, such as ions and peptides, can have dramatic effects on shape and elasticity of lipid membranes. A case in point is calcium and its crucial role in vesicle fusion[1], another example is the entry mechanism of cell penetrating peptides.[2] Using molecular dynamics, calcium and cell penetrating peptide mediated vesicle fusion were simulated in atomistic detail.[2] With a new, local approach[3] it became possible to extract the effect of the adsorbates on curvature elastic properties from the simulations. The results indicate that calcium specifically induces negative spontaneous curvature in those anionic lipid membranes which are are known to be susceptible to calcium mediated fusion. The molecular basis of curvature induction by cationic adsorbates is shown to be the induction of local stress through clustering.
In the following, I give an outline of my research program. The aim of the program is to use my simulation-based approach to advance the continuum theory of membrane elasticity. Specifically, the way proteins influence membrane properties is currently not well integrated with the Helfrich[4] theory. The unknown coupling terms are to be determined by generalization from specific examples. I introduce example systems chosen to represent the most important modes of interaction, but also address questions of practical relevance.
[1] E. Neher, R. Schneggenburger, Nature 406,889-893 2000
[2] C. Allolio, A. Magarkar, P. Jurkiewicz, K. Baxova, M. Javanainen, R.Sachl, M. Hof, D. Horinek, V. Heinz, R. Rachel, C. Ziegler, M. Cebecauer, A. Schrofel, P. Jungwirth, PNAS, 115, 11923-11928 2018
[3] C. Allolio, A. Haluts, D. Harries, Chem. Phys 514, 31-43 2018
[4] W. Helfrich, Z. Naturforsch. 28, 693-703 1973