colfosceril-palmitate and 1-2-dipalmitoyl-3-phosphatidylethanolamine

Menaquinones (MKs) are essential for electron transport in prokaryotes, and importantly, partially saturated MKs represent a novel virulence factor. However, little is known regarding how the degree of saturation in the isoprenyl side chain influences conformation or quinone redox potential. MenJ is an enzyme that selectively reduces the second isoprene unit on MK-9 and is contextually essential for the survival of Mycobacterium tuberculosis in J774A.1 macrophage-like cells, suggesting that MenJ may be a conditional drug target for pathogenic mycobacteria. Therefore, fundamental information about the properties of this system is important, and we synthesized the simplest MKs, unsaturated MK-1 and the saturated analogue, MK-1(H

Topics: 1,2-Dipalmitoylphosphatidylcholine; Bacterial Proteins; Membranes, Artificial; Micelles; Models, Molecular; Molecular Conformation; Oxidation-Reduction; Oxidoreductases Acting on CH-CH Group Donors; Phosphatidylethanolamines; Proton Magnetic Resonance Spectroscopy; Vitamin K 2

High molecular weight polycyclic aromatic hydrocarbons (HMW-PAHs) are persistent organic pollutants which due to their limited biodegradability accumulate in soils where their increased presence can lead to the impoverishment of the decomposer organisms. As very hydrophobic PAHs easily penetrate cellular membranes of soil bacteria and can be incorporated therein, changing the membrane fluidity and other functions which in consequence can lead to the death of the organism. The structure and size of PAH molecule can be crucial for its membrane activity; however the correlation between PAH structure and its interaction with phospholipids have not been investigated so far. In our studies we applied phospholipid Langmuir monolayers as model bacterial membranes and investigated how the incorporation of six structurally different PAH molecules change the membrane texture and physical properties. In our studies we registered surface pressure and surface potential isotherms upon the monolayer compression, visualized the monolayer texture with the application of Brewster angle microscopy and searched the ordering of the film-forming molecules with molecular resolution with the application of grazing incidence X-ray diffraction (GIXD) method. It turned out that the phospholipid-PAH interactions are strictly structure dependent. Four and five-ring PAHs of the angular or cluster geometry can be incorporated into the model membranes changing profoundly their textures and fluidity; whereas linear or large cluster PAHs cannot be incorporated and separate from the lipid matrix. The observed phenomena were explained based on structural similarities of the applied PAHs with membrane steroids and hopanoids.

Topics: 1,2-Dipalmitoylphosphatidylcholine; Bacteria; Cardiolipins; Cell Membrane; Kinetics; Phosphatidylethanolamines; Phosphatidylglycerols; Polycyclic Aromatic Hydrocarbons; Soil Pollutants; Structure-Activity Relationship; Thermodynamics; Unilamellar Liposomes

Hybrids composed of amphiphilic block copolymers and lipids constitute a new generation of biological membrane-inspired materials. Hybrid membranes resulting from self-assembly of lipids and polymers represent adjustable models for interactions between artificial and natural membranes, which are of key importance, e.g., when developing systems for drug delivery. By combining poly(dimethylsiloxane)-block-poly(2-methyl-2-oxazoline) amphiphilic copolymers (PDMS-b-PMOXA) with various phospholipids, we obtained hybrid films with modulated properties and topology, based on phase separation, and the formation of distinct domains. By understanding the factors driving the phase separation in these hybrid lipid-polymer films, we were able to use them as platforms for directed insertion of membrane proteins. Tuning the composition of the polymer-lipids mixtures favored successful insertion of membrane proteins with desired topological distributions (in polymer or/and lipid regions). Controlled insertion and location of membrane proteins in hybrid films make these hybrids ideal candidates for numerous applications where specific spatial functionality is required.

Topics: 1,2-Dipalmitoylphosphatidylcholine; Dimethylpolysiloxanes; Membrane Proteins; Membranes, Artificial; Models, Biological; Phosphatidylcholines; Phosphatidylethanolamines; Polyamines; Polymerization; Thermodynamics

All-atom molecular dynamics (MD) simulations were used to investigate the thermal phase behavior of two hydrated phospholipids, namely, DPPC and DPPE, at the atomic level. The trajectories in the MD simulations clearly identified the structures of DPPC in the crystalline (Lc), gel (Lβ), ripple (Pβ), and liquid-crystalline (Lα) phases and those of DPPE in the Lc and Lα phases. The physicochemical and structural properties of these phases agree well with the experimental results. Moreover, the structural transformations between phases were observed. In the Lβ phase, forces are directed in opposite directions in the upper and lower layers of the bilayer. These forces, which are due to the thermal motion of each monolayer, strongly influence the series of phase transitions from Lβ to Pβ. The MD simulations in this work can provide an understanding of the dynamics of the lipid bilayer in each thermal phase and suggest the mechanism that generates the Pβ phase.

Topics: 1,2-Dipalmitoylphosphatidylcholine; Lipid Bilayers; Molecular Dynamics Simulation; Phase Transition; Phosphatidylethanolamines; Phospholipids; Temperature