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Beat H Meier - One of the best experts on this subject based on the ideXlab platform.
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proton detected nmr spectroscopy of nanodisc embedded membrane proteins mas solid state vs solution state methods
Journal of Physical Chemistry B, 2017Co-Authors: Nilsalexander Lakomek, Lukas Frey, Stefan Bibow, Anja Bockmann, Roland Riek, Beat H MeierAbstract:The structural and dynamical characterization of membrane proteins in a lipid bilayer at physiological pH and Temperature and free of crystal constraints is crucial for the elucidation of a structure/dynamics–activity relationship. Toward this aim, we explore here the properties of the outer-membrane protein OmpX embedded in lipid bilayer nanodiscs using proton-detected magic angle spinning (MAS) solid-state NMR at 60 and 110 kHz. [1H,15N]-correlation spectra overlay well with the corresponding solution-state NMR spectra. Line widths as well as line intensities in solid and solution both depend critically on the sample Temperature and, in particular, on the crossing of the lipid Phase Transition Temperature. MAS (110 kHz) experiments yield well-resolved NMR spectra also for fully protonated OmpX and both below and above the lipid Phase Transition Temperature.
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proton detected nmr spectroscopy of nanodisc embedded membrane proteins mas solid state vs solution state methods b
The Journal of Physical Chemistry, 2017Co-Authors: Nilsalexander Lakomek, Lukas Frey, Stefan Bibow, Anja Bockmann, Roland Riek, Beat H MeierAbstract:The structural and dynamical characterization of membrane proteins in a lipid bilayer at physiological pH and Temperature and free of crystal constraints is crucial for the elucidation of a structure/dynamics–activity relationship. Toward this aim, we explore here the properties of the outer-membrane protein OmpX embedded in lipid bilayer nanodiscs using proton-detected magic angle spinning (MAS) solid-state NMR at 60 and 110 kHz. [¹H,¹⁵N]-correlation spectra overlay well with the corresponding solution-state NMR spectra. Line widths as well as line intensities in solid and solution both depend critically on the sample Temperature and, in particular, on the crossing of the lipid Phase Transition Temperature. MAS (110 kHz) experiments yield well-resolved NMR spectra also for fully protonated OmpX and both below and above the lipid Phase Transition Temperature.
Digambara Patra - One of the best experts on this subject based on the ideXlab platform.
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interaction of curcumin with 1 2 dioctadecanoyl sn glycero 3 phosphocholine liposomes intercalation of rhamnolipids enhances membrane fluidity permeability and stability of drug molecule
Colloids and Surfaces B: Biointerfaces, 2017Co-Authors: Zeinab Moussa, Mazhar Chebl, Digambara PatraAbstract:Stability of curcumin in neutral and alkaline buffer conditions has been a serious concern for its medicinal applications. We demonstrate that the stability of curucmin can be improved in 1,2-Dioctadecanoyl-sn-glycero-3-phosphocholine (DSPC) liposomes. Curcumin strongly partition into liquid crystalline Phase compared to solid gel Phase of DSPC liposomes. Variation of fluorescence intensity of curcumin associated with liposomes with Temperature successfully determines Phase Transition Temperature of DSPC liposomes. However, at higher molar ratio curcumin can influence Phase Transition Temperature by intercalating into deep hydrophobic layer of liposomes and facilitating fusion of two membrane Phases. Rhamnolipids (RLs) are recently being applied for various biomedical applications. Here, we have explored new insight on intercalation of rhamnolipids with DSPC liposomes. Intercalation of rhamnolipids exceptionally increases partition of curcumin into solid gel Phase of DSPC liposomes, whereas this increase is moderate in liquid crystalline Phase. Fluorescence quenching study establishes that permeability and fluidity of the DSPC liposomes are enhanced in the presence of RLs. Membrane permeability and fluidity can be improved further by increasing the percentage of RLs in DSPC liposomes. The Phase Transition Temperature of DSPC liposomes decreases with increase in percentage of RLs in DSPC liposomes by encouraging fusion between solid gel and liquid crystalline Phases. Intercalation of RLs is found to further boost stability of drug, curcumin, in DSPC liposomes. Thus, mixing RLs with DSPC liposomes could potentially serve as a good candidate for drug delivery application.
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ionic liquid expedites partition of curcumin into solid gel Phase but discourages partition into liquid crystalline Phase of 1 2 dimyristoyl sn glycero 3 phosphocholine liposomes
Journal of Physical Chemistry B, 2013Co-Authors: Elsy El Khoury, Digambara PatraAbstract:The hydrolysis of curcumin in alkaline and neutral buffer conditions is of interest because of the therapeutic applicability of curcumin. We show that hydrolysis of curcumin can be remarkably suppressed in 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) liposomes. The fluorescence of curcumin sensitively detects the Phase Transition Temperature of liposomes. However, at greater concentrations, curcumin affects the Phase Transition Temperature, encouraging fusion of two membrane Phases. The interaction of curcumin with DMPC is found to be strong, with a partition coefficient value of Kp = 2.78 × 105 in the solid gel Phase, which dramatically increases in the liquid crystalline Phase to Kp = 1.15 × 106. The importance of ionic liquids as green solvents has drawn interest because of their toxicological effect on human health; however, the impact of ionic liquids (ILs) on liposomes is not yet understood. The present study establishes that ILs such as 1-methyl-3-octylimidazolium chloride (moic) affect the p...
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effect of curcumin on liposome curcumin as a molecular probe for monitoring interaction of ionic liquids with 1 2 dipalmitoyl sn glycero 3 phosphocholine liposome
Photochemistry and Photobiology, 2012Co-Authors: Digambara Patra, Elsy El Khoury, Diana Ahmadieh, Shaza Darwish, Rana M TafechAbstract:Recent increase and wider use of ionic liquids (ILs) for various applications has drawn attention to their toxicological consequence on human health. The present study explores effects of three different kinds of widely used ILs, such as 1-methyl-3-octylimidazolium chloride, 1-buytl-3-methyl imadazolium tetrafluoroborate and 1-benzyl-3-methyl imidazolium tetrafluoroborate, on liposome properties of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) by applying curcumin as molecular probe. Fluorescence intensity of curcumin is reported as a novel rotor which is sensitive to viscosity and thus the fluidity of the solvent. It follows a linear relationship of log fluorescence vs viscosity as proposed by Forster-Hoffmann equation. Curcumin binds strongly to liposome. At low concentration, the lipophilic drug curcumin does not appreciably influence the Phase Transition Temperature of DPPC but as concentration reaches high levels significantly depresses the Phase Transition Temperature. ILs diminish membrane fluidity. 1-methyl-3-octylimidazolium chloride disorders membrane properties by lowering the Phase Transition as is observed for higher concentration of curcumin, but 1-buytl-3-methyl imidazolium tetrafluoroborate and 1-benzyl-3-methyl imidazolium tetrafluoroborate do not modify Phase Transition Temperature perceptibly; rather they broaden the Phase Transition at low molar concentration ratio. The three different kinds of ILs under study behave similarly at a high IL:DPPC ratio (1:2), while they behave differently at lower ratios (1:10-1:5).
Nilsalexander Lakomek - One of the best experts on this subject based on the ideXlab platform.
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proton detected nmr spectroscopy of nanodisc embedded membrane proteins mas solid state vs solution state methods
Journal of Physical Chemistry B, 2017Co-Authors: Nilsalexander Lakomek, Lukas Frey, Stefan Bibow, Anja Bockmann, Roland Riek, Beat H MeierAbstract:The structural and dynamical characterization of membrane proteins in a lipid bilayer at physiological pH and Temperature and free of crystal constraints is crucial for the elucidation of a structure/dynamics–activity relationship. Toward this aim, we explore here the properties of the outer-membrane protein OmpX embedded in lipid bilayer nanodiscs using proton-detected magic angle spinning (MAS) solid-state NMR at 60 and 110 kHz. [1H,15N]-correlation spectra overlay well with the corresponding solution-state NMR spectra. Line widths as well as line intensities in solid and solution both depend critically on the sample Temperature and, in particular, on the crossing of the lipid Phase Transition Temperature. MAS (110 kHz) experiments yield well-resolved NMR spectra also for fully protonated OmpX and both below and above the lipid Phase Transition Temperature.
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proton detected nmr spectroscopy of nanodisc embedded membrane proteins mas solid state vs solution state methods b
The Journal of Physical Chemistry, 2017Co-Authors: Nilsalexander Lakomek, Lukas Frey, Stefan Bibow, Anja Bockmann, Roland Riek, Beat H MeierAbstract:The structural and dynamical characterization of membrane proteins in a lipid bilayer at physiological pH and Temperature and free of crystal constraints is crucial for the elucidation of a structure/dynamics–activity relationship. Toward this aim, we explore here the properties of the outer-membrane protein OmpX embedded in lipid bilayer nanodiscs using proton-detected magic angle spinning (MAS) solid-state NMR at 60 and 110 kHz. [¹H,¹⁵N]-correlation spectra overlay well with the corresponding solution-state NMR spectra. Line widths as well as line intensities in solid and solution both depend critically on the sample Temperature and, in particular, on the crossing of the lipid Phase Transition Temperature. MAS (110 kHz) experiments yield well-resolved NMR spectra also for fully protonated OmpX and both below and above the lipid Phase Transition Temperature.
Tadashi Takenaka - One of the best experts on this subject based on the ideXlab platform.
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large electrostrain near the Phase Transition Temperature of bi0 5na0 5 tio3 srtio3 ferroelectric ceramics
Applied Physics Letters, 2008Co-Authors: Yuji Hiruma, Yoshinori Watanabe, Hajime Nagata, Yoshitaka Imai, Tadashi TakenakaAbstract:(1-x)(Bi0.5Na0.5)TiO3–xSrTiO3 (abbreviated as BNST100x) was prepared by a conventional ceramic fabrication process. The depolarization Temperature Td, rhombohedral-tetragonal Phase Transition Temperature TR-T, and the Temperature Tm of the maximum dielectric constant were determined from the Temperature dependence of the dielectric and piezoelectric properties. It is revealed that BNST100x forms a morphotropic Phase boundary of rhombohedral ferroelectric and pseudocubic (tetragonal) paraelectric at x=0.26–0.28 for BNST100x, and a very large strain and normalized strain d33* of 0.29% and 488pm∕V, respectively, were obtained at x=0.28. In addition, it was clarified that the intermediate Phase between TR-T (⩾Td) and Tm shows relaxor behavior.
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Phase Transition Temperature and electrical properties of bi1 2na1 2 tio3 bi1 2a1 2 tio3 a li and k lead free ferroelectric ceramics
Journal of Applied Physics, 2008Co-Authors: Yuji Hiruma, Hajime Nagata, Kazushige Yoshii, Tadashi TakenakaAbstract:(1−x)(Bi1∕2Na1∕2)TiO3–x(Bi1∕2Li1∕2)TiO3 and (1−x)(Bi1∕2Na1∕2)TiO3–x(Bi1∕2K1∕2)TiO3 (abbreviated as BNLT100x and BNKT100x, respectively) ceramics were prepared by the conventional ceramic fabrication process. In this study, the depolarization Temperature Td, rhombohedral-tetragonal Phase Transition Temperature TR-T, and the Temperature of the maximum dielectric constant Tm were determined from the Temperature dependences of the dielectric and piezoelectric properties. The results showed that Td of BNLT100x and BNKT100x increased to 199 and 209°C, respectively, at the rhombohedral composition. In addition, we revealed that Td is related to the magnitude of the rhombohedrality 90-α and the tetragonality c∕a. We studied the piezoelectric properties in detail, and the relationship between Td and piezoelectric properties was clarified. Moreover, we discussed the ferroelectricity of the middle Phases of Td−TR-T and TR-T−Tm.
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Phase Transition Temperatures of divalent and trivalent ions substituted bi1 2na1 2 tio3 ceramics
Key Engineering Materials, 2007Co-Authors: Yuji Hiruma, Yoshinori Watanabe, Hajime Nagata, Tadashi TakenakaAbstract:The Phase Transition Temperatures of divalent and trivalent ions substituted (Bi1/2Na1/2)TiO3 ceramics were investigated in detail by electrical measurement. BNT ceramics substituted by divalent (Ca2+, Sr2+ and Ba2+) and trivalent (La3+, Nd3+, Ho3+ and Yb3+) ions were prepared by conventional ceramic fabrication process. For these ceramics, the depolarization Temperature, Td, the rhombohedral-tetragonal Phase Transition Temperature, TR-T, and the Temperature of the maximum dielectric constant, Tm, were determined on the basis of the Temperature dependences of dielectric and piezoelectric properties. In this study, we demonstrated the relationship between Phase Transition Temperature and ionic radius of ions substituted in the A-site of BNT ceramics.
Lukas Frey - One of the best experts on this subject based on the ideXlab platform.
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proton detected nmr spectroscopy of nanodisc embedded membrane proteins mas solid state vs solution state methods
Journal of Physical Chemistry B, 2017Co-Authors: Nilsalexander Lakomek, Lukas Frey, Stefan Bibow, Anja Bockmann, Roland Riek, Beat H MeierAbstract:The structural and dynamical characterization of membrane proteins in a lipid bilayer at physiological pH and Temperature and free of crystal constraints is crucial for the elucidation of a structure/dynamics–activity relationship. Toward this aim, we explore here the properties of the outer-membrane protein OmpX embedded in lipid bilayer nanodiscs using proton-detected magic angle spinning (MAS) solid-state NMR at 60 and 110 kHz. [1H,15N]-correlation spectra overlay well with the corresponding solution-state NMR spectra. Line widths as well as line intensities in solid and solution both depend critically on the sample Temperature and, in particular, on the crossing of the lipid Phase Transition Temperature. MAS (110 kHz) experiments yield well-resolved NMR spectra also for fully protonated OmpX and both below and above the lipid Phase Transition Temperature.
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proton detected nmr spectroscopy of nanodisc embedded membrane proteins mas solid state vs solution state methods b
The Journal of Physical Chemistry, 2017Co-Authors: Nilsalexander Lakomek, Lukas Frey, Stefan Bibow, Anja Bockmann, Roland Riek, Beat H MeierAbstract:The structural and dynamical characterization of membrane proteins in a lipid bilayer at physiological pH and Temperature and free of crystal constraints is crucial for the elucidation of a structure/dynamics–activity relationship. Toward this aim, we explore here the properties of the outer-membrane protein OmpX embedded in lipid bilayer nanodiscs using proton-detected magic angle spinning (MAS) solid-state NMR at 60 and 110 kHz. [¹H,¹⁵N]-correlation spectra overlay well with the corresponding solution-state NMR spectra. Line widths as well as line intensities in solid and solution both depend critically on the sample Temperature and, in particular, on the crossing of the lipid Phase Transition Temperature. MAS (110 kHz) experiments yield well-resolved NMR spectra also for fully protonated OmpX and both below and above the lipid Phase Transition Temperature.