CRC 858 B07 - Thermodynamic and Dynamic Equilibrium of Fluid-Fluid-Phases in Membrane Lipids

Basic data for this project

Description

Membrane lipids show the ability of generating fluid-fluid-phases, so called "rafts", in equilibrium. The aim of project B7 is to get a deeper insight into the raft formation process from a theoretical point of view. Rafts can already be obtained in ternary systems (e.g. in the presence of suitable lipids A and B and cholesterol (chol; type C)). The more mobile part then is enriched by B, the less mobile part exhibits more A and C. Chol is essential for the formation of rafts. Herein, cooperative processes are involved from two points of views: On the one hand the presence of chol makes the system AB "non-ideal" enough for phase separation. On the other hand the formation process itself is strongly dependant on the complex interaction of the degrees of freedom of chain conformation and translation. This process is not understood on neither the microscopic scale nor the mesoscopic scale. We want to tackle the problem of raft formation on two different levels: On the one hand we are aiming to perform microscopic simulations on the molecular dynamic with "coarse-grained" (CG) models. These models are sufficiently detailed to enable microscopic analyses; however, they are also sufficiently simplified in comparison to atomic perspectives in order to handle at least the initial phase of raft formation. On the other hand we want to carry out grid simulations with a minimum of freedom degrees for each molecule. The interaction mode of choice between the molecules themselves then can be obtained from the CG-simulations. From a theoretical point of view such models might also be analyzed on mean-field level in order to get a more detailed insight into the phase behavior.