SIMULATION OF THE DYNAMICS OF POLYUNSATUR ATED LIPIDS OF BIOLOGICAL-MEMBRANES

Molecular dynamics simulations were performed for the docosahexaene C2 2H34 and docosan C22H46 chains, which are typical components of phosph olipids in biological membranes. The calculations were carried on at t wo temperatures of 276 K and 320 K. The time of each computation cover ed 600 ps. The torsion angles variations Phi(i)(t), i=1, 2, ..., 21 ha s been analysed. It has been demonstrated that in docosan Phi(i)(t) ar e oscillating with the amplitudes of 10-15 degrees, which are slightly increasing with the temperature. The average torsion angle positions correspond to the rotation-isomeric model. In docosahexaene chain the amplitudes of the torsion angles oscillations around a simple bond, co nnected to a double one, are about twice greater and their requencies are about 3.5 times less then the docosan have. It has been noted that these angles also possess states, living up to 5 ps, which do not cor respond to the regions of the minimum potential energy of molecular fr agments. Average frequency of conformational transitions in docosahexa ene chain is about six times greater than in the docosan one.