Synthesis of spin-labelled 2-(16′-(N-oxyl-4″,4″-dimethyloxazolidine)stearoyl)-phosphatidylcholine

1980 ◽  
Vol 58 (2) ◽  
pp. 143-146 ◽  
Author(s):  
D. J. Vaughan ◽  
N. Z. Stanacev
Keyword(s):  
Protein Interactions ◽  
Egg Yolk ◽  
Molar Ratio ◽  
Resonance Spectroscopy ◽  
Scanning Calorimetry ◽  
Spin Resonance ◽  
Dimyristoyl Phosphatidylcholine ◽  
Label Probe ◽  
Lipid Protein Interactions ◽  
Good Agreement

Chemical synthesis of spin-labelled lecithin 2-(16′-(N-oxyl-4″,4″-dimethyloxazolidine)-stearoyl)-phosphatidylcholine was achieved by reaction of equimolar amounts of purified egg yolk lyso-lecithin with commercially available 16-(N-oxyl-4′,4′-dimethyloxazolidine)stearic acid activated with N,N-carbonyldiimidazole. After purification by silicic acid column chromatography, spin-labelled lecithin was obtained in 52.2% yield and had an ester:phosphorus:spin molar ratio of 2.0:1.1:1.0. When dimyristoyl-phosphatidylcholine and dimyristoyl-phosphatidylcholine:cholesterol (10:1) liposomes, containing 2-(16′-(N-oxyl-4″,4″-dimethyloxazolidine)stearoyl)-phosphatidylcholine as a probe, were examined for thermotropic changes monitored by electron spin resonance spectroscopy, transition temperatures of 24.0 and 24.2 °C, respectively, were obtained in a very good agreement with previously reported values obtained with different probes and by different techniques, and with our own differential scanning calorimetry measurements. The potential usefulness of synthetic 2-(16′-(N-oxyl-4″,4″-dimethyloxazolidine)stearoyl)-phosphatidylcholine as a spin-label probe in studies of lipid–protein interactions in biological membranes was discussed.

scholarly journals Different modes of interaction of pulmonary surfactant protein SP-B in phosphatidylcholine bilayers

1997 ◽  
Vol 327 (1) ◽  
pp. 133-138 ◽  
Author(s):  
Antonio CRUZ ◽  
Cristina CASALS ◽  
Kevin M. W. KEOUGH ◽  
Jesús PÉREZ-GIL
Keyword(s):  
Aqueous Phase ◽  
Protein Interactions ◽  
Pulmonary Surfactant ◽  
Fluorescence Emission ◽  
Tryptophan Fluorescence ◽  
Egg Yolk ◽  
Surfactant Protein ◽  
Scanning Calorimetry ◽  
Adsorption Activity ◽  
Egg Yolk Phosphatidylcholine

Pulmonary surfactant-associated protein B (SP-B) has been incorporated into vesicles of dipalmitoyl phosphatidylcholine (DPPC) or egg yolk phosphatidylcholine (PC) by two different procedures to characterize the dependence of lipid–protein interactions on the method of reconstitution. In method A the protein was dissolved in a small volume of either methanol or 60% (v/v) acetonitrile and injected into an aqueous phase containing phospholipid vesicles. In method B the vesicles were prepared by injection of a mixture of phospholipid and SP-B dissolved in methanol or aqueous acetonitrile. Both methods of reconstitution led to the extensive interaction of SP-B with PC bilayers as demonstrated by co-migration during centrifugation, marked protection against proteolysis, change in the fluorescence emission intensity of SP-B, and protection of SP-B tryptophan fluorescence from quenching by acrylamide. SP-B promoted the rapid adsorption of DPPC on an air/liquid interface irrespective of the method of protein reconstitution. However, the interfacial adsorption activity of SP-B reconstituted by method B remained stable for hours, but that of SP-B prepared by method A decreased with time. Electron microscopy showed that the injection of SP-B into an aqueous phase containing PC or DPPC vesicles (method A) induced a rapid aggregation of vesicles. By contrast, a much longer time was required for detecting vesicle aggregation when the protein was reconstituted by co-injection of SP-B and phospholipids (method B). The presence of 5% (w/w) SP-B in DPPC bilayers prepared by method B broadened the differential scanning calorimetry thermogram and decreased the enthalpy of the transition. In contrast, the injection of SP-B into preformed DPPC vesicles (method A) did not influence the gel-to-liquid phase transition of DPPC bilayers. Taken together, these results indicate that the mode and extent of interaction of SP-B with surfactant phospholipids depends on the conditions of preparation of lipid/protein samples, and that care should be taken in the interpretation of findings from reconstituted systems on the role of these surfactant proteins in the alveolar space.

Heat-resistant and photoluminescent indole-based poly(ether sulfone)s

2017 ◽  
Vol 30 (4) ◽  
pp. 475-479 ◽  
Author(s):  
Wenxuan Wei ◽  
Li Yang ◽  
Guanjun Chang
Keyword(s):  
Thermal Stability ◽  
High Performance ◽  
Proton Nuclear Magnetic Resonance ◽  
Resonance Spectroscopy ◽  
Condensation Polymerization ◽  
High Glass Transition Temperature ◽  
Scanning Calorimetry ◽  
Good Thermal Stability ◽  
High Performance Polymers ◽  
Good Agreement

Indole-based poly(ether sulfone)s (PINESs), as novel high-performance polymers, have been obtained by the condensation polymerization of 4-hydroxyindole and hydroquinone with activated difluoro monomers via a catalyst-free nucleophilic substitution reaction. The structures of the polymers are characterized by means of Fourier transform infrared and proton nuclear magnetic resonance spectroscopy, and the results show good agreement with the proposed structures. Differential scanning calorimetry and thermogravimetric analysis measurements exhibit that polymers possess high glass transition temperature ( Tgs > 245°C) and good thermal stability with high decomposition temperatures ( Tds > 440°C). In addition, due to their special structure, PINESs are endowed with significantly strong photonic luminescence in N, N-dimethylformamide.

scholarly journals Stacking in lipid vesicle-tubulin mixtures is an artifact of negative staining.

1980 ◽  
Vol 86 (3) ◽  
pp. 881-884 ◽  
Author(s):  
V Melchior ◽  
C J Hollingshead ◽  
M E Cahoon
Keyword(s):  
Protein Interactions ◽  
Incubation Time ◽  
Phosphotungstic Acid ◽  
Sodium Tungstate ◽  
Lipid Vesicle ◽  
Sample Concentration ◽  
Dimyristoyl Phosphatidylcholine ◽  
Egg Lecithin ◽  
Lipid Protein Interactions ◽  
Uranyl Oxalate

Multilamellar stacking seen in negatively stained lipid vesicle-tubulin mixtures has been attributed to lipid-protein interactions (Caron, J. M., and R. D. Berlin, 1979, J. Cell Biol. 81:665-671). We show that this stacking is produced by the phosphotungstic acid used for staining, independent of the presence of tubulin in the sample. The morphology of negatively stained single bilayer vesicles obtained from dimyristoyl phosphatidylcholine or egg lecithin is specifically dependent upon the choice of metal stain. Uranyl oxalate maintains the appearance of unilamellar vesicles. After staining with sodium tungstate, the lipids form a network of multilayered lamellae with a periodicity of approximately 55 A. Phosphotungstic acid produces stacks of flattened vesicles with a period of approximately 115 A as well as broader multilamellar structures having a 55 A repeat. The stain-determined morphology is not markedly altered by sample concentration, incubation time, or temperature, or by the presence of tubulin.

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