Unit Cell Structure of Water-Filled Monoolein into Inverted Hexagonal (HII) Mesophase Modeled by Molecular Dynamics.

Citation:

Vesselin L Kolev, Ivanova, Anela N, Madjarova, Galia K, Aserin, Abraham , and Garti, Nissim. . 2014. “Unit Cell Structure Of Water-Filled Monoolein Into Inverted Hexagonal (Hii) Mesophase Modeled By Molecular Dynamics.”. Journal Of Physical Chemistry B, 118, 20, Pp. 5459–5470. doi:10.1021/jp411138r.

Abstract:

The study investigates the unit cell structure of inverted hexagonal (HII) mesophase composed of monoolein (1-monoolein, GMO) and water using atomistic mol. dynamics methods without imposing any restraints on lipid and water mols. Statistically meaningful and very contrast images of the radial mass d. distribution, scrutinizing also the sep. components water, monoolein, the polar headgroups of the lipids, the double bond, and the termini of the hydrocarbon chain (the tail), are obtained. The lipid/water interface structure is analyzed based on the obtained water d. distribution, on the estd. no. of hydrogen bonds per monoolein headgroup, and on the headgroup-water radial distribution functions. The headgroup mass d. distribution demonstrates hexagonal shape of the monoolein/water interface that is well-defined at higher water/monoolein ratios. Water interacts with the headgroups by forming a three-layer diffusive mass d. distribution, and each layer's shape is close to hexagonal, which is an indication of long-range structural interactions. It is found that the monoolein headgroups form a const. no. of hydrogen bonds leaving an excessive amt. of water mols. outside the first lipid coordination sphere. Furthermore, the quantity of water at the monoolein/water interface increases steadily upon extension of the unit cell, so the interface should have a very dynamic structure. Investigation of the hydrocarbon residues reveals high compression and well-expressed structuring of the tails. The tails form a very compressed and constrained structure of defined layers across the unit cell with properties corresponding to a more densely packed nonpolar liq. (oil). Due to the hexagonal shape the 2D packing frustration is const. and does not depend on the water content. All reported structural features are based on averaging of the at. coordinates over the time-length of the simulation trajectories. That kind of processing allows the observation of the water/GMO interface shape and its stability and mobility at a time scale close to the ones of the intermol. interactions. [on SciFinder(R)]
Last updated on 06/28/2020