FAST 2-DIMENSIONAL COMPUTER-SIMULATION OF BILAYER HEMIFUSION

Computer simulation of model membranes was used to evaluate the possib le mechanism of lipid bilayer fusion. The simplified two dimensional m odel of the membrane cross section was used as an analog of three dime nsional reality. Lipid molecules were represented by rodlike structure s, and forces between them were limited to attraction/repulsion intera ctions described by a simple energy function with a minimum: 300-400 m olecules were modeled in every simulation. Using the energy minimizati on procedure, it was possible to obtain stable linear or circular bila yer structures (two dimensional analogs of planar membranes and liposo mes). In response to changes in attraction/repulsion equilibrium betwe en molecules these bilayers were able to reorganize via cooperative pr ocess. By increasing the headgroup attraction parameter for contacting monolayers, it was possible to induce formation of a zone of hemifusi on in the area of bilayer contact. The possible correlation between co operative bilayer rearrangement in the model and in real bilayers is d iscussed.