Molecular dynamics investigation of polar diacylglycerolipid monolayers: bond ordering properties

摘要

Molecular dynamics simulations of six monolayers composed of the molecules 2,3-diacyl-D-glycerolipids that contained stearoyl in the position 3 and stearoyl, oleoyl, linoleoyl, linolenoyl, arachidonoyl or docosahexaenoyl in the position 2 have been carried out; 1.5 nanosecond simulations were performed at T=303 K for the monolayers of unsaturated molecules and at T=326 K for saturated one. The average areas per lipid molecule over the simulations were 65.6 A{top}o{sup}2 in 18:0/18:0-monolayer, 66.2 A{top}o{sup}2 in 18:0/18:1ω9cis-monolayer, 66.1 A{top}o{sup}2 in 18:0/18:2ω6cis-, 67.4 A{top}o{sup}2 in 18:0/18:3ω3cis-, 70.6 A{top}o{sup}2in 18:0/20:4ω6cis- and 71.4 A{top}o{sup}2 in 18:0/22:6ω3cis-monolayer. The C-H bond orientation distributions and C-H bond order parameter profiles about the monolayer normals have been calculated. The bond orientation distribution function widths turned out to be depended on both the segment location in the chain and the segment chemical structure. The computer simulation data indicated the widths of the distributions of CH{sub}2-groups located between the double bonds of polyunsaturated chains to be much greater than that of C-H bonds of double bond carbons (broadening effect).