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1.
As a model for 1,2-bis(2,4-octadecadienoyl)-sn-glycero-3-phosphorylcholine, a doubly unsaturated membrane-forming lipid molecule, force-field (MMP2) calculations were performed on S-1,2-bis(2-dibutenoyl)glycerol, and CNDO/S-calculations 2 1 CNDO: Complete neglect of differential overlap, a semi-empirical quantum-mechanical method. on the derived minimum-energy conformations of S-1,2-bis(2,4-hexadienoyl)glycerol. The energy hypersurface especially with respect to the dihedral angles along the C(1)-C(2) and the two C O ester bonds was explored and the rotational strength as a function of these angles was calculated. The two gauche-forms were found to be most stable, with a slight preference for the g−-form. The experimental circular dichroism data obtained for 1,2-bis(2,4-hexadienoyl)-sn-glycero-3-phosphorylcholine, the corresponding phosphorylcholine, indicate a dynamic equilibrium between two forms of opposite chirality possibly involving the g+-and the g−-forms. 相似文献
2.
A convenient route to prepare of 1,2-dipalmitoyl-sn-glycero-3-phospho-1′-myo-inositol and its phosphorothioate analogue, 1,2-dipalmitoyl-sn-glycero-3-phosphorothio-1′-myo-inositol, is described. 相似文献
3.
Kathleen Kayganich Robert C. Murphy 《Journal of the American Society for Mass Spectrometry》1991,2(1):45-54
Carboxylate anions arising from collision-induced dissociation (CID) of the [M - 15]- ion produced by fast atom bombardment (FAB) of glycerophosphocholine (GPCho) were previously shown to be produced in an abundance ratio of 1:3 for the carboxylic acids esterified at sn - 1 and sn - 2, respectively. This observation has been confirmed in a series of 13 synthetic GPCho molecular species. A good correlation was found between the isomeric purity of GPCho molecular species as determined by negative-ion FAB/CID analysis and the isomeric purity of the sn - 2 fatty acid using a phospholipase A2 assay. Negative-ion FAB mass spectra of several 1-0-alkyl-2-acyl-GPCho molecular species were found to be similar to those of diacyl GPCho. However, the cm spectra from the major high-mass ions are different from those of the diacyl species in that the [M - 15]- ion yields only one carboxylate anion and the [M - 86]- undergoes a neutral loss of the sn - 2 carboxylic acid as a major decomposition product. These results suggest several rules useful for structural characterization of GPCho molecular species by negative-ion tandem mass spectrometry (MS/MS): (1) For diacyl species, the mass of the two carboxyl anions plus the mass of the GPeho backbone (minus a methyl group) must correspond to the mass of the [M - 15] anion; (2) for diacyl species there is a carboxylate anion ratio approximately 1:3 for the substituents at sn - 1 and sn - 2; and (3) for alkylether species, only one fatty acyl group is present, and the difference between the [M - 15] ion and the GPCho backbone (minus methyl) plus the fatty acyl group at sn - 2 corresponds to an alkylether substituent. (4) Assignment of ether-linked molecular species can be made from the [M - 86]- ion, which has a strong neutral loss of the sn - 2 fatty acid. Analysis of GPCho isolated from human neutrophils by total lipid extraction and normal-phase HPLC was carried out by negative-ion FABand MS/MS. The major arachidonate-eontaining molecular species, which comprise only 5% of total GPCho, were identified by using precursor ion scans for the arachidonate anion, m/ z 303. Decomposition of identified. precursor ions permitted the assignment of those molecular species of GPCho that contain arachidonate at sn - 2 and identification of the substituent at the sn - 1 position. These results were compared to previously identified molecular species from human neutrophils. Several minor arachidonate-containing molecular species were tentatively identified. 相似文献
4.
《Tetrahedron: Asymmetry》2006,17(19):2731-2737
Enantiodiscrimination of ditryptophan enantiomers (l-Trp-l-Trp and d-Trp-d-Trp, l-Trp-d-Trp and d-Trp-l-Trp) was observed in bio-membrane models, such as micellar aggregates of 1,2-diheptanoyl-sn-glycero-3-phospatidylcholine (DHPC) and multilamellar vesicles of either 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) or 1,2-dimyristoyl-sn-glycero-3-phospatidylcholine (DMPC) by solution 1H NMR and HR-MAS 1H NMR, respectively. The attainment of resolved signals, allowed the first detection of enantiodiscrimination at a molecular level, and the identification of the site of chiral recognition and of the interactions and conformations of homo- and heterochiral dipeptides in large-sized aggregates formed by a common component of bio-membranes. 相似文献
5.
Jingqin Chen Adam C. Sedgwick Sajal Sen Yaguang Ren Qinchao Sun Calvin Chau Jonathan F. Arambula Tridib Sarma Liang Song Jonathan L. Sessler Chengbo Liu 《Chemical science》2021,12(29):9916
Photoacoustic imaging (PAI) relies on the use of contrast agents with high molar absorptivity in the NIR-I/NIR-II region. Expanded porphyrins, synthetic analogues of natural tetrapyrrolic pigments (e.g. heme and chlorophyll), constitute as potentially attractive platforms due to their NIR-II absorptivity and their ability to respond to stimuli. Here, we evaluate two expanded porphyrins, naphthorosarin (1) and octaphyrin (4), as stimuli responsive PA contrast agents for functional PAI. Both undergo proton-coupled electron transfer to produce species that absorb well in the NIR-II region. Octaphyrin (4) was successfully encapsulated into 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-poly(ethylene glycol) (DSPE-PEG2000) nanoparticles to afford OctaNPs. In combination with PAI, OctaNPs allowed changes in the acidic environment of the stomach to be visualized and cancerous versus healthy tissues to be discriminated.In this study, two expanded porphyrins, octaphyrin and naphthorosarin were evaluated as potential PA agents. The nanoparticle encapsulation of octaphyrin successfully enabled the visualization of acidic environments and the discrimination between cancerous and healthy tissues. 相似文献
6.
Neus Lozano Aurora Pinazo Ramon Pons Lourdes Prez Elias I. Franses 《Colloids and surfaces. B, Biointerfaces》2009,74(1):67-74
The binary surface interactions of some novel cationic diacyl glycerol arginine-based surfactants with model phospholipids, which are often used as model membrane components, are studied at 25 °C in aqueous solutions of 0.1 M sodium chloride. The surfactants are 1,2-dimyristoyl-rac-glycero-3-O-(Nα-acetyl-l-arginine) hydrochloride (1414RAc) and 1,2-dilauroyl-rac-glycero-3-O-(Nα-acetyl-l-arginine) hydrochloride (1212RAc), and they are important as potential antimicrobial agents which are biodegradable and with less toxicity than other cationic surfactants. The phospholipids are 1,2-dipalmitoyl-sn-glycero-3-phosphatidylcholine (DPPC) and 1,2-dimyristoyl-sn-glycero-3-phosphatidylcholine (DMPC). The equilibrium and dynamic surface tension of each surfactant, each phospholipid, and some of their binary mixtures are studied using the bubble surfactometry method at constant area or pulsating area conditions. In addition, the surface densities of pure and mixed monolayers of these compounds at the air/water interface are probed with infrared reflection–absorption spectroscopy (IRRAS). Steady state and dynamic surface tension synergism, or antisynergism in one case, and synergistic adsorption effects are detected for the mixed dispersions studied. The enhanced adsorption detected with IRRAS, and the enhanced dynamic and steady state surface tension lowering indicate strong miscibility and net attractive interactions between the compounds in the adsorbed mixed monolayers. 相似文献
7.
Juan F. Santarn M. Rico J. Guilleme A. Ribera 《Magnetic resonance in chemistry : MRC》1982,18(2):98-103
Two mixed-acid lecithins: 1-stearoyl-2-linoleyl-sn-glycero-3-phosphorylcholine (SLL) and 1-stearoyl-2-arachidonoyl-sn-glycero-3-phosphorylcholine (SAL) have been synthesized by phospholipase A2 digestion of 1,2-distearoyl-sn-glycero-3-phosphorylcholine (DSL), followed by reacylation of the lysolecithin with the desired fatty acid anhydride. 13C (25.2 MHz) NMR spectra of SLL and SAL in CDCl3 solution and in sonicated dispersions in 2H2O have been obtained. Complete spectral assignments are reported for the two molecules in both systems. 13C nuclear spin-lattice relaxation times (T1) of SLL and SAL in sonicated aqueous dispersions have also been measured. Relaxation rate profiles as a function of the chain segment position are in general agreement with those recently obtained from 2H NMR for similar systems. 相似文献
8.
Henri Ravald Amin Hedayati Moghaddam Shishir Jaikishan Marine Lavainne Susanne K. Wiedmer 《Journal of separation science》2023,46(18):2300414
Liposome capillary electrokinetic chromatography was used to investigate the interactions between three β-blockers of different hydrophobicity and various liposome solutions. The studied β-blockers comprised alprenolol, propranolol, and carvedilol. The composition of the liposome solutions, containing 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine, 1,2-dioleoyl-sn-glycero-3-phos-phoethanolamine, 1-palmitoyl-2-oleoyl-sn-glycero-3-phospho-l -serine, and cholesterol in various molar ratios, was designed by a response surface methodology-central composite design approach. Subsequently, after conducting the liposome capillary electrokinetic chromatography experiments and determining the retention factors from the electrophoretic mobilities of the compounds, and further calculating the distribution coefficients, an analysis of variance was performed. After extracting the statistical models, optimal operational conditions were obtained based on the developed models. To further investigate the interactions between the β-blockers and the liposomes, nanoplasmonic sensing experiments were carried out on two different liposome systems. The overall results demonstrate the strong influence of cholesterol and 1-palmitoyl-2-oleoyl-sn-glycero-3-phospho-l -serine on the distribution coefficients. 相似文献
9.
《Chemical physics letters》1987,136(6):539-545
Langmuir-Blodgett film alloys of PPDPC (1-palmitoyl-2-[10-(pyren-1-yl)]decanoyl-sn-glycero-3-phosphocholine) and DPPC (1,2-dipalmitoyl-sn-glycero-3-phosphatidylcholine) were assembled in varying molar proportions on quartz glass slides. The transferred layers were then characterized according to their pyrene excimer to monomer fluorescence intensity ratio iE/iM and fluorescence quantum yields as a function of film composition. The observed deviation from non-ideal mixing is considered to be due to the formation of regular distribution patterns of PPDPC in a DPPC lattice. The observed critical mole fractions of PPDPC evident as steps in IE/IM versus XPPDPC plots can be accounted for by a model involving a trigonal distribution of pyrenedecanoyl chains in the phospholipid acyl chain lattice. The implications of the distribution of PPDPC as superlattices to the excimer formation mechanism are discussed. 相似文献
10.
Interfacial, γ, and fluorescence measurements have been performed to evaluate the synergism in mixed cationic and zwitterionic phospholipid systems, viz. dodecyltrimethylammonium bromide plus 1,2-diheptanoyl-sn-glycero-3-phosphocholine (DHPC), tetradecyltrimethylammonium bromide plus DHPC, and hexadecyltrimethylammonium bromide plus DHPC mixtures. From the γ data the maximum surface excess and minimum area per molecule were computed and it was found that the former decreases and the latter increases with the increase in the fraction of cationic component in the binary mixture. Application of regular solution theory demonstrated that strong synergistic interactions are present which increase with the increase in length of the hydrocarbon tail of the cationic surfactant component. These interactions were considerably less in the monolayers than in the mixed micelles. The aggregation number, N agg, of DHPC shows a significant decrease upon induction of the cationic component and vice versa. The decrease in N agg is explained on the basis of an increase in the total polarity of the mixed micelles. 相似文献
11.
Daniel F. Kienle João V. de Souza Erik B. Watkins Tonya L. Kuhl 《Analytical and bioanalytical chemistry》2014,406(19):4725-4733
The thickness and refractive index of 1,2-dipalmitoyl-sn-glycero-3-phosphatidyl choline (DPPC) and 1,2-dipalmitoyl-sn-glycero-3-phosphoethanolamine (DPPE) monolayers Langmuir--Blodgett (LB) deposited on mica were measured in dry air and bulk water using multiple-beam interferometry (MBI). Measurements of thickness using atomic force microscopy (AFM) of identical monolayers, and X-ray reflectivity (XRR) of the monolayers on quartz were taken for comparison. The measurement of the properties of solid-supported monolayers in dry air allows lipid optical properties to be determined free from solvent effects. The thickness and refractive index measured by MBI were 25.5?±?0.6 Å and 1.485?±?0.007 for DPPE monolayers, and 23.9?±?0.5 Å and 1.478?±?0.006 for DPPC monolayers in dry air. These thicknesses are consistent with the other techniques used in this work as well as other measurements in the literature. The refractive indices of solid-supported lipid monolayers have not been previously measured. The values are higher than previous measurements on black lipid films done by reflectometry, which is attributed to increased lipid packing density and the absence of hydrocarbon solvents. Applying water to the monolayers had no measurable effect on their properties, indicating that any change in hydration was below detection. Figure
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12.
A series of double-chained phosphatidylcholines (PCs), 1,2-dioctadec-9′-ynoyl-sn-glycero-3-phosphocholine analogs containing perfluoroalkyl moieties (CF3, C2F5, n-C4F9 or n-C8F17) as the terminal segment in two hydrophobic chains, 1a-d, were synthesized. Equilibrium spreading pressures of these fluorinated PCs at the air-water interface were measured as an indication of monolayer stability, in order to obtain the minimal fluorine content in PC molecule efficient to exhibit monolayer stabilizing effect. The monolayer stability sigmoidally increased with the fluorine content in PC molecule and subsequently leveled off above a certain fluorine content, i.e., n-C4F9 moiety, at 25 °C. Under this condition, the replacement of at least five hydrogen atoms at the terminal hydrophobic segment in double-chained PC molecule by fluorine atoms, i.e., CF3CF2 moiety, is required to exhibit the monolayer stabilizing effect, whereas further fluorination of double-chained PC (F(CF2)n; n > 4) has a minor effect on the monolayer stability. 相似文献
13.
Amichai Yavlovich Alok Singh Sergey Tarasov Jacek Capala Robert Blumenthal Anu Puri 《Journal of Thermal Analysis and Calorimetry》2009,98(1):97-104
We describe a novel class of light-triggerable liposomes prepared from a photo-polymerizable phospholipid DC8,9PC (1,2-bis (tricosa-10,12-diynoyl)-sn-glycero-3-phosphocholine) and DPPC (1,2-Dipalmitoyl-sn-Glycero-3-Phosphocholine). Exposure to UV (254 nm) radiation for 0–45 min at 25 °C resulted in photo-polymerization of DC8,9PC in these liposomes and the release of an encapsulated fluorescent dye (calcein). Kinetics and extents of calcein release
correlated with mol% of DC8,9PC in the liposomes. Photopolymerization and calcein release occurred only from DPPC/DC8,9PC but not from Egg PC/DC8,9PC liposomes. Our data indicate that phase separation and packing of polymerizable lipids in the liposome bilayer are major
determinants of photo-activation and triggered contents release. 相似文献
14.
Manganese(III) complexes derived from the bis-Schiff bases N,N′-bis(5-fluorosalicylidene)-1,2-diaminoethane (H2La) and 3,4-bis(2-hydroxybenzylideneamino)pyridine (H2Lb), respectively, have been prepared and characterized by elemental analyses, IR, and single crystal X-ray crystallographic determination (CIF files CCDC nos. 997243 (I), 995896 (II)). The crystal of [MnLa(μ1,3-N3)] n (I) is orthorhombic: space group Pca21, a = 10.723(1), b = 13.430(1), c = 11.112(1) Å, V = 1600.2(2) Å3, Z = 4, R 1 = 0.0264, wR 2 = 0.0649. The crystal of [MnLb(N3)(CH3OH)] (II) is monoclinic: space group C2/c, a = 22.792(1), b = 14.4442(7), c = 12.8637(6) Å, β = 119.262(1)°, V = 3694.5(3) Å3, Z = 8, R 1 = 0.0367, wR 2 = 0.0776. The bis-Schiff base ligands coordinate to the metal atoms through phenolate O and imine N atoms. Each metal atom in the complexes is in octahedral coordination. The effects of the complexes on the antimicrobial activity against Staphylococcus aureus, Escherichia coli, and Candida albicans were studied. 相似文献
15.
Masaharu Kondo Mizuki Amano Takashi Joke Shuichi Ishigure Tomoyasu Noji Takehisa Dewa Yutaka Amao Mamoru Nango 《Research on Chemical Intermediates》2014,40(9):3287-3293
Photosystems, PSI and PSII isolated from Thermosynechococcus elongatus were successfully immobilized on a TiO2 nanostructured film for use in dye-sensitized biosolar cells (DSBCs). The photosystem complexes were also immobilized on an ITO electrode modified with 3-aminopropyltriethoxysilane by utilizing the interactions between the electrode and the surface of the PSI or PSII polypeptide. Illumination of the PSI and PSII complexes immobilized on the ITO electrode resulted in action spectra in the presence of methyl viologen, which corresponded to the absorption spectra of the complexes. Compared with the ITO electrode, PSI or PSII complexes assembled on the TiO2 electrode had much higher energy-conversion efficiency in the presence of an iodide/triiodide redox system of an ionic-liquid-based electrolyte. This could have interesting applications in the development of DSBCs. 相似文献
16.
A crude extract of a marine alga showed activity against the enzyme Myt1 kinase. Bioassay-directed fractionation led to the isolation of two bioactive glycoglycerolipids. Lipid 1 was identified as sn-1,2-dipalmityl-3-(N-palmityl-6-deoxy-6-amino-α-d-glucosyl) glycerol and lipid 2 as sn-1-palmityl-2-myristyl-3-(N-stearyl-6-deoxy-6-aminoglucosyl)glycerol. Compounds 1 and 2 had IC50 values of 0.12 and 0.43 μg/mL, respectively, in the Myt1 kinase inhibitory bioassay, and were inactive against Akt and Chk1 kinases. 相似文献
17.
Youn-Sik Lee David F. O'Brien 《Journal of polymer science. Part A, Polymer chemistry》1994,32(8):1437-1445
Polymerization of lipid assemblies may be usefully employed to alter the properties of the assemblies. The possible locations of the reactive group in the lipids include (1) the chain terminus, (2) the head group, and (3) near the lipid backbone. The third strategy yields polymerized assemblies which retain their head group functionality and lipid chain motion. We have designed and synthesized new members of this later category by the use of 2-methylene-substituted acyl chains. The main transition temperature (Tm) from gel to liquid crystalline phase of hydrated bilayers of 1-palmitoyl-2-(2-methylene)palmitoyl-sn-glycero-3-phosphocholine ( 1 ) and the disubstituted 1,2-bis(2-methylenepalmitoyl)-sn-glycero-3-phosphocholine ( 2 ) were 33.6 and 25.3°C, respectively. The Tm of the mono-substituted 1-oleoyl-2-(2-methylene)palmitoyl-sn-glycero-3-phosphocholine ( 3 ) bilayers was detected in a range from ?15 to ?10°C by x-ray diffraction. Hydrated bilayers of each individual lipid were successfully polymerized with a water-soluble initiator, azobis(2-amidinopropane) dihydrochloride (AAPD). These results indicate the lipid 2-methylene groups are accessible to the water interface. Thermal polymerization of the mono-substituted lipids in aqueous suspensions with AAPD, yielded oligomers. However the bis-2-methylene PC ( 2 ) was successfully polymerized to yield stabilized crosslinked bilayers. © 1994 John Wiley & Sons, Inc. 相似文献
18.
Makoto Yoshimoto Hideyuki Sakamoto Hiroshi Shirakami 《Colloids and surfaces. B, Biointerfaces》2009,69(2):281-287
Tetrameric bovine liver catalase (BLC) is unstable because of its dissociation into subunits at low enzyme concentrations and the conformational change of the subunits at high temperatures. In this work, for stabilization of BLC, the enzyme was covalently conjugated with liposome membranes composed of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC), cholesterol and 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine-N-glutaryl (NGPE). The NGPE, which was responsible for the BLC/membrane coupling, was altered from 0.05 to 0.2 in its liposomal mole fraction fG. The catalase-conjugated liposome (CCL) with fG of 0.15 showed the maximum number of the conjugated BLC molecules of 28 per liposome. The reactivity of CCLs to H2O2 was as high as that of free BLC at 25 °C in Tris–HCl buffer of pH 7.4. Among the CCLs, the catalyst with fG of 0.15 was the most stable at 55 °C in its enzyme activity in the buffer because the appropriate number of BLC/liposome covalent bonding prevented the dissociation-induced enzyme deactivation. Furthermore, the CCL showed much higher stability at 55 °C than the free BLC/enzyme-free liposome mixture and free BLC at the low BLC concentration of 340 ng/mL. This was because BLC in the CCL was located in the vicinity of the host membrane regardless of the catalyst concentration, which could induce the effective stabilization effect of the membrane on the enzyme tertiary structure as indicated by the intrinsic tryptophan fluorescence analysis. The results obtained demonstrate the high structural stability of BLC in the CCL system, which was derived from the covalent bonding and interaction between BLC and liposomes. 相似文献
19.
Stefan Zander Michael Hermes Fritz Scholz Andreas Gr?ning Christiane A. Helm Doris Vollmer Uwe Lendeckel Lorenz Schild 《Journal of Solid State Electrochemistry》2012,16(7):2391-2397
Giant unilamellar liposomes of the synthetic cardiolipin 1′,3′-bis[1,2-dimyristoyl-sn-glycero-3-phospho]-sn-glycerol give chronoamperometric current peaks at a stationary mercury electrode. The signals are due to the adhesion and spreading of the liposomes on the hydrophobic mercury surface. The potential dependence shows a minimum of the peak frequency at the point of zero charge, a large maximum of peak frequency at about ?0.2?V and a second, however, smaller maximum at ?0.8?V. The electrochemical behaviour of the liposomes indicates phase transitions of the cardiolipin which could be also observed in differential scanning calorimetry. 相似文献
20.
A mixed-acid monounsaturated lecithin, 1-palmitoyl-2-oleyl-sn-glycero-3-phosphorylcholine (POL), has been synthesized by phospholipase A2 digestion of 1,2 dipalmitoyl-sn-glycero-3-phosphorylcholine followed by reacylation of the lysolecithin with oleic anhydride. 1H (90 MHz) and 13C (25.2 MHz) NMR spectra of POL in CDCl3 solution and in sonicated dispersions in 2H2O have been obtained, and spin-lattice relaxation times measured. The relaxation times were characteristic of the type of structure formed and reflect molecular motion within the lecithin molecule in each structure. In both systems the spin-lattice relaxation times increase along the alkyl chains towards the terminal methyl group, showing a corresponding increase in the chain molecular motion, although there are significant differences in the gradation of the changes. 相似文献