Study of the structure and dynamics of interphase membrane / water in a clean membrane dimirystynowo - phosphatidylcholine ( DMPC ) and membrane mixed DMPC - cholesterol ( Chol ) was carried out using molecular dynamics simulation . The interphase region of the polar groups of lipids and water form an extensive network of connections . DMPC in the film influences the result of a connection : 1 ) through a water molecule , which simultaneously forms two hydrogen bonds with the negatively charged oxygen atoms of the PC ( water bridges ) , they combine DMPC 76 % of the particles , 2) between the positively charged choline group and a negatively charged oxygen atom PC ( steam load ) , they combine 93 % DMPC molecules . At any time, 98% of all DMPC molecules in the membrane are bonded together by bridges of Water and / or steam load . In the area of the interface of DMPC - Chol membrane , in addition to PC -PC connections are also analogous the PC- Chol by 1 ) Water bridges , 2 ) pairs of load , 3 ) direct hydrogen bonds . The combinations of the involved molecules of about 98 % and 70% DMPC molecules Chol . Average lifetimes of connections are the order of 1 ns or longer , these connections are dynamic and subject to the lifetime of a temporary ruptures .