Relationship between water permeation and flip-flop motion in a bilayer membrane

Abstract

We have investigated the effect of the flip-flop motion on the water permeation into the lipid membrane.

Lipid Flip-Flop-Inducing Antimicrobial Phytochemicals from Gymnema sylvestre are Bacterial Membrane Permeability Enhancers

“…A variety of molecular species that induce defects in the lipid bilayer could induce lipid flip-flop in the biological membrane. 29 , 30 Accordingly, proteins (e.g., GPCRs and scramblases), peptides (e.g., gramicidin), and non-bilayer forming lipids (e.g., ceramides and oxidized lipids) are potential flippases. 29 , 31 , 32 However, their kinetics and mechanism of action differ significantly depending upon the nature of the flippase molecule and its membrane association.…”

“…These results indicate that phytochemicals in MEFGS cooperatively associate with the LUV lipid bilayer in a concentration- and time-dependent manner that probably results in the formation of lipid-flipping complexes (Figure ). A variety of molecular species that induce defects in the lipid bilayer could induce lipid flip-flop in the biological membrane. , Accordingly, proteins (e.g., GPCRs and scramblases), peptides (e.g., gramicidin), and non-bilayer forming lipids (e.g., ceramides and oxidized lipids) are potential flippases. ,, However, their kinetics and mechanism of action differ significantly depending upon the nature of the flippase molecule and its membrane association. Saponins partially permeate into biomimmetic membranes beyond their critical micelle concentrations with the hydrophilic moiety protruding out of the membrane and hydrophobic tail penetrating the bilayer …”

“…However, individual phytochemicals are of insufficient dimension to span the entire membrane bilayer that is required to form a trans-membrane pathway for membrane lipid flipping (Figure ). In contrast, the phytochemical aggregates in the membrane bilayer plausibly provide the hydrophilic surfaces that facilitate the transbilayer movement of the hydrophilic lipid head group across the bilayer. ,− Binding of MEFGS components to LUVs altered their rounded morphology, as detected by phase contrast microscopy (Figure C). The untreated control LUVs are rounded in shape with smooth surfaces, whereas treatment with MEFGS at an MEFGS/phospholipid (w/w) ratio of 2.5 led to the time-dependent change in vesicle shape, resulting in their irregular morphology.…”

DPD simulation to reproduce lipid membrane microdomains based on fragment molecular orbital calculations

“…To achieve this, researchers commonly use dissipative particle dynamics (DPD) and coarse-grained molecular dynamics simulations. In particular, DPD simulations are used to predict mesostructures, simulate lipid membranes, [40][41][42][43][44][45][46] polymer electrolyte membranes, 47) drug delivery systems, 48) and to design material properties. The simulations involve the analysis and design of each molecule and particle, which requires the use of χ parameters to describe their interactions.…”