COMPUTER-SIMULATION OF THE TEMPERATURE-DEPENDENT AND HYDRATION-DEPENDENT LATERAL DIFFUSION OF PHOSPHATIDYLCHOLINE IN LIPID BILAYERS

A lattice model of a lipid bilayer near the so-called main phase trans ition between the liquid crystalline (L(alpha)) and the gel (L(beta)) phase is presented. It is based on a two-state model, Jump dynamics ar e defined for the lattice molecules to simulate lateral diffusion. The temperature and hydration dependence of the lateral diffusion coeffic ients of the model are calculated for the L(alpha) phase using Monte C arlo simulation techniques. The results obtained allow the estimation of the hydration dependent part of the lateral diffusion activation en ergy by thermodynamical quantities. We compare these results with meas ured activation energies of dipalmitoylphosphatidylcholine (DPPC) and propose a model to describe the total lateral diffusion activation ene rgy of such systems.