Biophysical Society Conference | Tahoe 2022

Molecular Biophysics of Membranes

Poster Abstracts

22-POS Board 6 LIPID/WATER INTERFACE OF GALACTOLIPID BILAYERS IN DIFFERENT LYOTROPIC LIQUID-CRYSTALLINE PHASES Jakub Hryc 1 ; Michal Markiewicz 1 ; Marta Pasenkiewicz-Gierula 1 ; 1 Jagiellonian University, Department of Computational Biophysics and Bioinformatics, Kraków, Poland Model membranes are hydrated lipid bilayers of a controlled lipid composition typical for the specific biomembrane. Each bilayer has three distinct regions, the water phase, the polar interface and the nonpolar hydrocarbon chain region. Of the regions, the lipid/water interface is the most structurally and dynamically complex. It consists of various lipid polar groups and water molecules; the polar groups are in constant motions and the interfacial water molecules, even though they are predominantly bound to the polar groups, exchange with bulk water fast.In this study, the organisation of the lipid/water interface of bilayers composed of galactolipids with both α -linolenoyl (di-18:3, cis) acyl chains, in three different lyotropic liquid-crystalline phases, is analysed and compared. The studied systems include monogalactosyldiglyceride (MGDG) and digalactosyldiglyceride (DGDG) bilayers in the lamellar phase, MGDG double bilayer in the stalk structure and the inverse hexagonal MGDG phase (H II ). For each system, lipid-water as well as direct and water mediated lipid-lipid interactions are identified and their lifetimes assessed. The analyses concern interactions among lipids belonging to the same bilayer leaflet and among lipids belonging to the opposite leaflets at the onset of the new phase formation.

70