Reconstitution of the glycosylphosphatidylinositol-anchored protein Thy-1: interaction with membrane phospholipids and galactosylceramide

1999 ◽  
Vol 77 (3) ◽  
pp. 189-200 ◽  
Author(s):  
Kara L Reid-Taylor ◽  
Joseph WK Chu ◽  
Frances J Sharom
Keyword(s):  
Phase Transition ◽  
Differential Scanning Calorimetry ◽  
Lipid Bilayer ◽  
Liquid Crystalline ◽  
Membrane Surface ◽  
Membrane Phospholipids ◽  
Scanning Calorimetry ◽  
Transition Enthalpy ◽  
Striking Change ◽  
Lipid Bilayer Vesicles

Glycosylphosphatidylinositol (GPI)-anchored membrane proteins are proposed to interact preferentially with glycosphingolipids and cholesterol to form microdomains, which may play an important role in apical targeting and signal transduction. The objective of the present study was to investigate the interaction of the GPI-anchored protein Thy-1 with phospholipids and a glycosphingolipid. Purified Thy-1 was reconstituted into lipid bilayer vesicles of dimyristoyl-phosphatidylcholine (DMPC) alone or in combination with galactosylceramide (GC). The ability of Thy-1 to perturb the gel to a liquid-crystalline phase transition of DMPC was examined by differential scanning calorimetry. As the mole fraction of Thy-1 increased, the phase transition enthalpy, deltaH, declined. Analysis indicated that each molecule of Thy-1 perturbed over 50 phospholipids, suggesting that, in addition to the anchor insertion into the bilayer, the protein itself may interact with the membrane surface. Inclusion of 5% w/w GC in the bilayer resulted in a striking change in the interaction of Thy-1 with phospholipids. At low Thy-1 content, there was a reduction in the phase transition temperature and an increase in phospholipid cooperativity, suggesting the formation of Thy-1/GC-enriched domains. deltaH initially decreased with increasing Thy-1 content of the bilayer; however, at higher Thy-1 mole ratios, deltaH rose again. These results are interpreted in terms of a model whereby, at low protein:lipid mole ratios, Thy-1 preferentially sequesters GC to form enriched microdomains. At high protein:lipid mole ratios, Thy-1 may alter its conformation in response to steric crowding within these domains such that its interaction with the bilayer surface is reduced.Key words: glycosylphosphatidylinositol anchor, Thy-1 antigen, reconstitution, lipid bilayer, glycosphingolipid, differential scanning calorimetry, dynamic light scattering.

Phase Transitions by Dilatometry, Part I: Synthesis, Characterisation and Isotropic to Smectic-A and Smectic-A to Smectic-B Transitions in Two Liquid Crystalline Higher Homologues of N-(p-n-nonyloxybenzylidene) p-n-alkylanilines

2004 ◽  
Vol 59 (9) ◽  
pp. 537-542 ◽  
Author(s):  
C. Rama Chandra Prabhu ◽  
S. Lakshminarayana ◽  
V. G. K. M. Pisipatia
Keyword(s):  
Phase Transition ◽  
Differential Scanning Calorimetry ◽  
Transition Temperature ◽  
Liquid Crystalline ◽  
Scanning Calorimetry ◽  
First Order ◽  
Smectic A ◽  
M 12 ◽  
Phase Variants ◽  
Enthalpy Data

Two higher homologues of N(p-n-nonyloxybenzylidene)p-n-alkylanilines, viz. the 9O.m series with m = 12 and 16, are synthesised and characterised by thermal microscopy, differential scanning calorimetry and density studies. The compounds exhibit the phase variants smectic-A, smectic-B and smectic-G. Density studies reveal the first order nature of the isotropic to smectic-A and smectic-A to smectic-B transitions. An estimate of the pressure dependence of the phase transition temperature, using volume and enthalpy data, is presented. A comparison of these results with those reported on nO.m and other liquid crystalline compounds is presented.

Studies on the purified Na+,Mg2+-ATPase from Acholeplasma laidlawii B membranes: a differential scanning calorimetric study of the protein–phospholipid interactions

1990 ◽  
Vol 68 (1) ◽  
pp. 161-168 ◽  
Author(s):  
Rajan George ◽  
Ruthven N.A.H. Lewis ◽  
Ronald N. McElhaney
Keyword(s):  
Phase Transition ◽  
Liquid Crystalline ◽  
Lipid Phase ◽  
Scanning Calorimetry ◽  
Lipid Phase Transition ◽  
Acholeplasma Laidlawii ◽  
Lipid Ratios ◽  
Dimyristoyl Phosphatidylcholine ◽  
Transition Enthalpy ◽  
Crystalline Phase Transition

The purified Na+, Mg2+-ATPase from the Acholeplasma laidlawii B plasma membrane was reconstituted with dimyristoyl phosphatidylcholine and the lipid thermotropic phase behavior of the proteoliposomes formed was investigated by differential scanning calorimetry. The effect of this ATPase on the host lipid phase transition is markedly dependent on the amount of protein incorporated. At low protein/lipid ratios, the presence of increasing quantities of ATPase in the proteoliposomes increases the temperature and enthalpy while decreasing the cooperativity of the dimyristoyl phosphatidylcholine gel to liquid–crystalline phase transition. At higher protein/lipid ratios, the incorporation of increasing amounts of this enzyme does not further alter the temperature and cooperativity of the phospholipid chain-melting transition, but progressively and markedly decreases the transition enthalpy. Plots of lipid phase transition enthalpy versus protein concentration suggest that at the higher protein/lipid ratios each ATPase molecule removes approximately 1000 dimyristoyl phosphatidylcholine molecules from participation in the cooperative gel to liquid–crystalline phase transition of the bulk lipid phase. These results indicate that this integral transmembrane protein interacts in a complex, concentration-dependent manner with its host phospholipid and that such interactions involve both hydrophobic interactions with the lipid bilayer core and electrostatic interactions with the lipid polar head groups at the bilayer surface.Key words: Acholeplasma laidlawii B, Na+,Mg2+-ATPase, differential scanning calorimetry, lipid-protein interactions.

Observation of Direct Phase Transition Smectic A ↔ Blue Phase in a Liquid Crystalline Mixed System

1984 ◽  
Vol 39 (7) ◽  
pp. 658-661 ◽  
Author(s):  
H. Onusseit ◽  
H. Stegemeyer
Keyword(s):  
Phase Transition ◽  
Phase Diagram ◽  
Differential Scanning Calorimetry ◽  
Liquid Crystalline ◽  
Mixed System ◽  
Scanning Calorimetry ◽  
Smectic A ◽  
Smectic A Phase ◽  
Blue Phase ◽  
Blue Phases

Hithertoo, for all liquid-crystalline samples exhibiting Blue Phases (BP) it has been found that these phases occur between the cholesteric and the isotropic state. In the mixed system of cholesteryl myristate and an azoxybenzene derivative a phase transition from the smectic A phase directly to the BP has been observed. The phase diagram has been obtained by differential scanning calorimetry and is discussed together with the helical pitch behaviour.

scholarly journals Synthesis and mesomorphic properties of calamitic malonates and cyanoacetates tethered to 4-cyanobiphenyls

2012 ◽  
Vol 8 ◽  
pp. 371-378 ◽  
Author(s):  
Katharina C Kress ◽  
Martin Kaller ◽  
Kirill V Axenov ◽  
Stefan Tussetschläger ◽  
Sabine Laschat
Keyword(s):  
Differential Scanning Calorimetry ◽  
Ambient Temperature ◽  
Liquid Crystalline ◽  
X Ray Diffraction ◽  
Cyanoacetic Acid ◽  
Scanning Calorimetry ◽  
Isotropic Liquid ◽  
X Ray ◽  
Nematic Phases ◽  
Mesomorphic Properties

4-Cyano-1,1'-biphenyl derivatives bearing ω-hydroxyalkyl substituents were reacted with methyl 3-chloro-3-oxopropionate or cyanoacetic acid, giving liquid-crystalline linear malonates and cyanoacetates. These compounds formed monotropic nematic phases at 62 °C down to ambient temperature upon cooling from the isotropic liquid. The mesomorphic properties were investigated by differential scanning calorimetry, polarizing optical microscopy and X-ray diffraction (WAXS).

Inosose-Flüssigkristalle / Inosose Liquid Crystals

1990 ◽  
Vol 45 (7) ◽  
pp. 1084-1090 ◽  
Author(s):  
Klaus Praefcke ◽  
Bernd Kohne ◽  
Andreas Eckert ◽  
Joachim Hempel
Keyword(s):  
Differential Scanning Calorimetry ◽  
Liquid Crystal ◽  
High Temperature ◽  
Liquid Crystalline ◽  
Structural Features ◽  
Lyotropic Liquid Crystal ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Alkyl Chains

Six S,S-dialkyl acetals 2a-f of inosose (1), tripodal in structure, have been synthesized, characterized and investigated by optical microscopy and differential scanning calorimetry (d.s.c.). The four S,S-acetals 2c-f with sufficiently long alkyl chains are thermotropic liquid crystalline; 2 e and 2 f are even dithermomesomorphic. Each of these four inosose derivatives 2c-f exhibits monotropically a most likely cubic mesophase (MI); in addition 2e and 2f show enantiotropically a hexagonal mesophase (Hx) with a non-covalent, supramolecular H-bridge architecture. Whereas the nature of the optically isotropic mesophase MI needs further clarification the stable high temperature mesophase Hx of 2 e and 2 f has been established by a miscibility test using a sugar S,S-dialkyl acetal also tripodal in structure and with a Hx phase proved by X-ray diffraction, but in contrast to 2 with an acyclic hydrophilic part. Similarities of structural features between the Hx-phases of 2e and 2f as well as of other thermotropic and lyotropic liquid crystal systems are discussed briefly.

scholarly journals Synthesis, Mesomorphism and the Optical Properties of Alkyl-deuterated Nematogenic 4-[(2,6-difluorophenyl)ethynyl]biphenyls

Materials ◽  
2021 ◽  
Vol 14 (16) ◽  
pp. 4653
Author(s):  
Jakub Herman ◽  
Piotr Harmata ◽  
Michał Czerwiński ◽  
Olga Strzeżysz ◽  
Marta Pytlarczyk ◽  
...  
Keyword(s):  
Molecular Structure ◽  
Mass Spectrometry ◽  
Differential Scanning Calorimetry ◽  
Optical Properties ◽  
Liquid Crystalline ◽  
Near Infrared ◽  
Synthesis And Characterization ◽  
Molecular Approach ◽  
Scanning Calorimetry

The synthesis and characterization of new deuterated liquid crystal (LC) compounds based on phenyl tolane core is described in this paper. The work presents an alternative molecular approach to the conventional LC design. Correlations between molecular structure and mesomorphic and optical properties for compounds which are alkyl-hydrogen terminated and alkyl-deuterium, have been drawn. The compounds are characterized by mass spectrometry (electron ionization) analysis and infrared spectroscopy. They show enantiotropic nematic behavior in a broad temperature range, confirmed by a polarizing thermomicroscopy and differential scanning calorimetry. Detailed synthetic procedures are attached. Synthesized compounds show a significantly reduced absorption in the near-infrared (NIR) and medium-wavelength infrared (MWIR) radiation range, and stand as promising components of medium to highly birefringent liquid crystalline mixtures.

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