University of Waterloo
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Carnegie Mellon University
The Gaussian curvature modulus κG of lipid bilayers likely contributes more than 100 kcal/mol to every cellular fission or fusion event. This huge impact on membrane remodeling energetics might be a factor that co-determines the complex lipid composition of biomembranes through tuning of κG. Yet, its value has been measured only for a handful of simple lipids, and no simulation has so far determined it better than a factor of two, rendering a systematic investigation of such enticing speculations impossible. In this talk I will propose a highly accurate method to determine κG in computer simulations. It relies on the interplay between curvature stress and edge tension of partially curved axisymmetric membrane discs and requires determining their closing probability. For two coarse grained lipid models of different resolution this method gives κG and its relation to the normal bending modulus κ. The elastic ratio κG/κ can be determined with a few percent statistical accuracy. Its value agrees with the scarce experimental data, and its change with spontaneous lipid curvature is compatible with theoretical expectations, thereby granting additional information on monolayer properties. I also show that an alternative determination of these elastic parameters based on moments of the lateral stress profile gives markedly different and unphysical values.