Lipid Compositions of Liquid-Ordered and Liquid-Disordered Phases in Ternary Membranes of Sphingomyelin, Cholesterol, and Dioleoylphosphatidylcholine Determined by H NMR: Stearoyl-Sphingomyelin Compared with Its Palmitoyl Counterpart.

Sphingomyelin (SM) and cholesterol are the major lipids in the signaling platforms of cell membranes, known as lipid rafts. In particular, SM with a stearoyl chain (C18-SM) is abundant in specific tissues such as the brain, the most cholesterol-rich organ, whereas the distribution of palmitoyl (C16)-SM is ubiquitous. Here, we reveal the differences between palmitoyl- and stearoyl-SM in lipid-lipid interactions based on the tie lines obtained from the H solid-state NMR spectra of bilayer systems composed of SM/dioleoylphosphatidylcholine/cholesterol 33:33:33 and 40:40:20.

Design, synthesis of ceramide 1-phosphate analogs and their affinity for cytosolic phospholipase A as evidenced by surface plasmon resonance.

Ceramide 1-phosphate (C1P) is a lipid mediator that specifically binds and activates cytosolic phospholipase Aα (cPLAα). To elucidate the structure-activity relationship of the affinity of C1P for cPLAα in lipid environments, we prepared a series of C1P analogs containing structural modifications in the hydrophilic parts and subjected them to surface plasmon resonance (SPR). The results suggested the presence of a specific binding site for cPLAα on the amide, 3-OH and phosphate groups in C1P structure.

Protein-lipid acyl chain interactions: Depth-dependent changes of segmental mobility of phospholipid in contact with bacteriorhodopsin.

Boundary lipids surrounding membrane proteins play an essential role in protein function and structure. These protein-lipid interactions are mainly divided into electrostatic interactions between the polar amino acids of proteins and polar heads of phospholipids, and hydrophobic interactions between protein transmembrane sites and phospholipid acyl chains. Our previous report (Kawatake et al.

Urine protein quantification in human urine on boron-doped diamond electrodes based on the electrochemical reaction of Coomassie brilliant blue.

Urinalysis is attracting interest in personal healthcare management as part of a general move to improve quality of life. Urine contains various metabolites and the protein level in urine is an indicator of kidney function. In this study, a novel electrochemical sensing system based on boron-doped diamond (BDD) electrodes was developed for the detection of protein concentrations in human urine.

Effect of the number of sugar units on the interaction between diosgenyl saponin and membrane lipids.

Saponin is the main bioactive component of the Dioscorea species, which are traditionally used for treating chronic diseases. An understanding of the interaction process of bioactive saponins with biomembranes provides insights into their development as therapeutic agents. The biological effects of saponins have been thought to be associated with membrane cholesterol (Chol).

Combined effect of the head groups and alkyl chains of archaea lipids when interacting with bacteriorhodopsin.

Bacteriorhodopsin (bR), a transmembrane protein with seven α-helices, is highly expressed in the purple membrane (PM) of archaea such as Halobacterium salinarum. It is well known that bR forms two-dimensional crystals with acidic lipids such as phosphatidylglycerol phosphate methyl ester (PGP-Me)-a major component of PM lipids bearing unique chemical structures-methyl-branched alkyl chains, ether linkages, and divalent anionic head groups with two phosphodiester groups. Therefore, we aimed to determine which functional groups of PGP-Me are essential for the boundary lipids of bR and how these functionalities interact with bR.

Molecular Dynamics of Glycolipids in Liposomes.

Glycosphingolipids (GSLs) in the mammalian plasma membrane are essential for various biological events as they form glycolipid-rich membrane domains, such as lipid rafts. GSLs consist of a certain oligosaccharide head group and a ceramide tail with various lengths of acyl chains. The structure of the head group as well as the carbon number and degree of the unsaturation of the acyl chain are known to regulate the membrane distributions and interleaflet couplings of GSLs by altering physicochemical properties, such as dynamics, interactions, and cluster sizes.

Behavior of Triterpenoid Saponin Ginsenoside Rh2 in Ordered and Disordered Phases in Model Membranes Consisting of Sphingomyelin, Phosphatidylcholine, and Cholesterol.

The ginsenoside Rh2 (Rh2) is a saponin of medicinal ginseng, and it has attracted much attention for its pharmacological activities. In this study, we investigated the interaction of Rh2 with biological membranes using model membranes. We examined the effects of various lipids on the membrane-disrupting activity of Rh2 and found that cholesterol and sphingomyelin (SM) had no significant effect.

Experimental and theoretical investigations into the mechanism of interactions between membrane-bound fatty acids and their binding protein: A model system to investigate the behavior of lipid acyl chains in contact with proteins.

The interaction of proteins with hydrophobic ligands in biological membranes is an important research topic in the life sciences. The hydrophobic nature of ligands, especially their lack of water solubility, often makes it difficult to experimentally investigate their interactions with proteins, thus hampering quantitative evaluation based on thermodynamic parameters. The fatty acid-binding proteins, particularly FABP3, discussed in this review can recognize fatty acids, a primary component of membrane lipids, with high affinity.

Lipid chain-driven interaction of a lipidated Src-family kinase Lyn with the bilayer membrane.

-Myristoylation is a process of ubiquitous protein modification, which promotes the interaction of lipidated proteins on cell surfaces, in conjunction with reversible -palmitoylation. We report the cooperative lipid-lipid interaction of two acyl chains of proteins, which increases the protein-membrane interaction and facilitates selective targeting of membranes containing anionic lipids. Lyn is a member of the Src family kinases distributed on the membrane surface by -myristoyl and neighbouring -palmitoyl chain anchors at the unique N-terminus domain.

Molecular substructure of the liquid-ordered phase formed by sphingomyelin and cholesterol: sphingomyelin clusters forming nano-subdomains are a characteristic feature.

As a model of lipid rafts, the liquid-ordered (Lo) phase formed by sphingomyelin (SM) and cholesterol (Cho) in bilayer membranes has long attracted the attention of biophysics researchers. New approaches and methodologies have led to a better understanding of the molecular basis of the Lo domain structure. This review summarizes studies on model membrane systems consisting of SM/unsaturated phospholipid/Cho implying that the Lo phase contains SM-based nanodomains (or nano-subdomains).

A New Pathway for CO Reduction Relying on the Self-Activation Mechanism of Boron-Doped Diamond Cathode.

By means of an initial electrochemical carbon dioxide reduction reaction (eCORR), both the reaction current and Faradaic efficiency of the eCORR on boron-doped diamond (BDD) electrodes were significantly improved. Here, this effect is referred to as the self-activation of BDD. Generally, the generation of carbon dioxide radical anions (CO ) is the most recognized pathway leading to the formation of hydrocarbons and oxygenated products.

Amphotericin B assembles into seven-molecule ion channels: An NMR and molecular dynamics study.

Amphotericin B, an antifungal drug with a long history of use, forms fungicidal ion-permeable channels across cell membranes. Using solid-state nuclear magnetic resonance spectroscopy and molecular dynamics simulations, we experimentally elucidated the three-dimensional structure of the molecular assemblies formed by this drug in membranes in the presence of the fungal sterol ergosterol. A stable assembly consisting of seven drug molecules was observed to form an ion conductive channel.

Depth-Dependent Segmental Melting of the Sphingomyelin Alkyl Chain in Lipid Bilayers.

The chain melting of lipid bilayers has often been investigated in detail using calorimetric methods, such as differential scanning calorimetry (DSC), and the resultant main transition temperature is regarded as one of the most important parameters in model membrane experiments. However, it is not always clear whether the hydrocarbon chains of lipids are gradually melting along the depth of the lipid bilayer or whether they all melt concurrently in a very narrow temperature range, as implied by DSC. In this study, we focused on stearoyl-d-sphingomyelin (SSM) as an example of raft-forming lipids.

Effect of cholesterol on the lactosylceramide domains in phospholipid bilayers.

Lactosylceramide (LacCer) in the plasma membranes of immune cells is an important lipid for signaling in innate immunity through the formation of LacCer-rich domains together with cholesterol (Cho). However, the properties of the LacCer domains formed in multicomponent membranes remain unclear. In this study, we examined the properties of the LacCer domains formed in Cho-containing 1-palmitoyl-2-oleoyl phosphatidylcholine (POPC) membranes by deuterium solid-state NMR and fluorescence lifetimes.

Impact of Intrinsic and Extrinsic Factors on Cellular Sphingomyelin Imaging with Specific Reporter Proteins.

Sphingomyelin (SM) is a major sphingolipid in mammalian cells. Although SM is enriched in the outer leaflet of the cell plasma membrane, lipids are also observed in the inner leaflet of the plasma membrane and intracellular organelles such as endolysosomes, the Golgi apparatus and nuclei. SM is postulated to form clusters with glycosphingolipids (GSLs), cholesterol (Chol), and other SM molecules through hydrophobic interactions and hydrogen bonding.

FRET detects lateral interaction between transmembrane domain of EGF receptor and ganglioside GM3 in lipid bilayers.

Ganglioside GM3 in the plasma membranes suppresses cell growth by preventing the autophosphorylation of the epidermal growth factor receptor (EGFR). Biological studies have suggested that GM3 interacts with the transmembrane segment of EGFR. Further biophysical experiments are particularly important for quantitative evaluation of the peptide-glycolipid interplay in bilayer membranes using a simple reconstituted system.