Cell membranes are composed mainly of phospholipids which are in turn, composed of five major chemical elements: carbon, hydrogen, nitrogen, oxygen, and phosphorus. Recent studies have suggested the possibility of sustaining life if the phosphorus is substituted by arsenic. Although this issue is still controversial, it is of interest to investigate the properties of arsenated-lipid bilayers to...

Trehalose preserves lipid bilayers during dehydration and rehydration by replacing water to form hydrogen bonds between its own OH groups and lipid headgroups. We compare the lipid conformation and dynamics between trehalose-protected lyophilized membranes and hydrated membranes, to assess the suitability of the trehalose-containing membrane as a matrix for membrane protein structure determinat...

Membrane fusion between uncharged lipid vesicles can be triggered by the peptide sequence 'B18' from the fertilization protein 'bindin', but it only proceeds efficiently in the presence of Zn(2+) ions. We studied (i) the interaction of Zn(2+) with the fusogenic peptide B18, (ii) the binding of B18 to 1-palmitoyl-2-oleoylglycero-3-phosphocholine (POPC), and (iii) the ternary system POPC/B18/Zn(2...

β2 Adrenergic receptor (β2AR) is a kind of G-protein coupled receptors (GPCRs) which transduce a wide range of extracellular signals into intracellular messages responsible for the regulation of diverse cell functions. Because of their functional ubiquity, GPCR is one of the most important drug targets in pharmaceutical industry. Although recent crystallographic studies provided both the active...

We present a highly sensitive nuclear-magnetic resonance technique to study membrane dynamics that combines the temporary encapsulation of spin-hyperpolarized xenon ((129)Xe) atoms in cryptophane-A-monoacid (CrAma) and their indirect detection through chemical exchange saturation transfer. Radiofrequency-labeled Xe@CrAma complexes exhibit characteristic differences in chemical exchange saturati...

The effects of cholesterol on the dynamics of cholestane spin probe (CSL) in various phosphatidylcholine-cholesterol mixed model membranes are examined. The lateral diffusion, D of CSL in DMPC/POPC/cholesterol ternary mixtures, is measured utilizing an improved dynamic imaging electron spin resonance method. It shows a factor of two decrease at 10 mol % and 25 degrees C, whereas it shows only a...

The activity of cyclo-RRRWFW (c-WFW) against Escherichia coli has been shown to be modulated by the aromatic motif and the lipopolysaccharides (LPS) in the bacterial outer membrane. To identify interaction sites and to elucidate the mode of c-WFW action, peptides were synthesized by the replacement of tryptophan (W) with analogs having altered hydrophobicity, dipole and quadrupole moments, hydr...

We used an automated Langmuir-Pockels surface balance to characterize the air-water interfacial properties of cholesterol (CH) and its derivatives with hydrophilic OH and F substitutions at isologous sites on the sterol body or side chain. We studied 6-fluorocholesterol, 25-fluorocholesterol, 25,26,26,26,27,27,27-heptafluorocholesterol, 7alpha-hydroxycholesterol, 7beta-hydroxycholesterol, 25-hy...

The dynamics and aggregation of a beta-sheet antimicrobial peptide, protegrin-1 (PG-1), are investigated using solid-state NMR spectroscopy. Chemical shift anisotropies of F12 and V16 carbonyl carbons are uniaxially averaged in 1,2-dilauryl-sn-glycero-3-phosphatidylcholine (DLPC) bilayers but approach rigid-limit values in the thicker 1-palmitoyl-2-oleoyl-sn-glycerol-3-phosphatidylcholine (POPC...

For canonical lipid raft mixtures of cholesterol (chol), N-palmitoylsphingomyelin (PSM), and 1-palmitoyl-2-oleoylphosphatidylcholine (POPC), electron paramagnetic resonance (EPR) of spin-labeled phospholipids--which is insensitive to domain size--is used to determine the ternary phase diagram at 23°C. No phase boundaries are found for binary POPC/chol mixtures, nor for ternary mixtures with PSM...