The Experts below are selected from a list of 327 Experts worldwide ranked by ideXlab platform
Hiroshi Umakoshi - One of the best experts on this subject based on the ideXlab platform.
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Detection of L-Proline-Catalyzed Michael Addition Reaction in Model BioMembrane
Journal of Chemistry, 2019Co-Authors: Masanori Hirose, Keishi Suga, Shigenori Sugisaki, Hiroshi UmakoshiAbstract:A method to detect the L-proline- (L-Pro-) catalyzed Michael addition reaction in model bioMembranes has been established, using N-[p(2-benzimidazolyl)phenyl]maleimide and acetone as reactants. The effect of Liposome Membranes on this reaction was kinetically analyzed using fluorescence spectroscopy. The kinetics of the reaction were different from those of the constituent lipids of the Liposomes. Zwitterionic 1,2-dipalmitoyl-sn-glycero-3-phosphocholine Liposome, which is in the solid-ordered phase, had a better value of reaction rate, suggesting that the reaction rate constants of this reaction in Liposome Membrane systems could be regulated by the characteristics of the Liposome Membrane (i.e., the phase state and surface charge). Based on the results obtained, a plausible model of the L-Pro-catalyzed Michael addition reaction was discussed. The obtained results provide us with an easily detectable method to assess the reactivity of L-Pro in biological systems.
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Hydrolase-Like Activity Provided by Zinc(II) and Oleoyl-Histidine at Liposome Membrane Surface
Colloids and Interfaces, 2018Co-Authors: Atsushi Tauchi, Keishi Suga, Hiroshi UmakoshiAbstract:Carbonic anhydrase (CA) is a hydrolase enzyme possessing an active center composed of three histidines (His), zinc(II) (Zn2+), and a hydration water. Here we report the hydrolase-like catalytic activity provided by the oleoyl-histidine (O-His) modified on Liposome Membranes. O-His was synthesized by the amide bond between oleic acid and His, and was incorporated into 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) and 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) Liposomes. The hydrolysis of p-nitrophenylacetate was promoted by O-His modified DOPC Liposomes in the presence of Zn2+. The formation of the active center was revealed by UV resonance Raman spectra. We conclude that the Liposome Membrane surface can be utilized as a platform for artificial hydrolysis reactions by modifying essential ligands inspired from natural enzymes.
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Chiral Selective Adsorption of Ibuprofen on a Liposome Membrane
The journal of physical chemistry. B, 2016Co-Authors: Yukihiro Okamoto, Yusuke Kishi, Takaaki Ishigami, Keishi Suga, Hiroshi UmakoshiAbstract:We investigated the key factors that affect enantioselective adsorption of ibuprofen (IBU) on a Liposome Membrane by changing its lipid composition: the Liposome Membrane shows different Membrane fluidity, surface charge, content of chiral components, and heterogeneity (nanodomain). Nonspecific interactions (hydrophobic and electrostatic) were revealed to be an important factor in enhancing the adsorbed amount of IBU, based on adsorption experiments carried out using single lipids (DPPC, DMPC, DOPC, and DLPC) and positively charged Liposomes (DOTAP and Liposome containing DC-Ch). Furthermore, control of the boundary edge (i.e., the nanodomain size) derived from the Membrane heterogeneity was important for enantioselective adsorption; as well as multiple weak interactions between lipid molecules and IBU enantiomers. The above findings provided a good index for constructing liposomal chiral adsorbents.
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Liposome Membrane as a Platform for the L-Pro-Catalyzed Michael Addition of trans-β-Nitrostyrene and Acetone.
Langmuir : the ACS journal of surfaces and colloids, 2015Co-Authors: Masanori Hirose, Keishi Suga, Takaaki Ishigami, Hiroshi UmakoshiAbstract:Herein, we show that the l-proline (l-Pro)-catalyzed Michael addition of trans-β-nitrostyrene and acetone can proceed in “water” using Liposome Membranes and that the Membrane fluidity and polarity are major controlling factors for this reaction. The highest conversion and rate constant of the reaction within the Liposomes was achieved with the 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC)/1,2-dipalmitoyl-3-trimethylammoniumpropane (DPTAP) system. The catalytic activity of l-Pro in the Liposome suspension was found to be comparable to that in a DMSO system. The reaction rate constant was found to be controlled by both the phase state of the Liposome Membrane and the surface charge on the Membrane. Greater enantioselectivity was achieved in the presence of the Liposomes than in DMSO solution, with corresponding enantiomeric excess values of 97.6% for the DOPC/DPTAP Liposome system and 10% in DMSO. The hydrophobic region of the Liposome Membrane, which is a relatively stable self-organizing system, can se...
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Liposome Membrane can induce self-cleavage of RNA that models the core fragments of hammerhead ribozyme.
European biophysics journal : EBJ, 2015Co-Authors: Keishi Suga, Seishiro Tanaka, Hiroshi UmakoshiAbstract:The hammerhead ribozyme (HHR) is one of smallest catalytic RNAs, composed of a catalytic core and three stems; it undergoes self-cleavage in the presence of divalent magnesium ions (Mg(2+)) or other cations. It is hypothesized that the function and metabolism of RNAs might be regulated via interaction with lipid Membranes in the prebiotic world. Using synthetic RNAs that model the core fragment of hammerhead ribozyme-like assembly (HHR-a), we investigated the enhancement of the self-cleavage reaction of HHR-a induced by the Liposomes, both in the absence and presence of Mg(2+). The HHR-a activity was enhanced by 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine (DOPE)/1,2-dioleoyl-sn-glycero-3-phosphocholine (DPPC) = 8/2 Liposome with Mg(2+), while other Liposomes did not so significant. In the presence of DOPE/DPPC = 8/2 Liposome, the HHR-a activity was observed without Mg(2+), revealed by the conformational change of the HHR inhibitor complex induced by the interaction with the Liposome. The UV resonance Raman spectroscopy analysis investigated the interaction between lipid molecules and nucleobases, suggesting that the ethanolamine group of DOPE molecules are assumed to act as monovalent cations alternative to Mg(2+), depending on the Liposome Membrane characteristics.
Toshinori Shimanouchi - One of the best experts on this subject based on the ideXlab platform.
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Application of Liposome Membrane as the reaction field: A case study using the Horner–Wadsworth–Emmons reaction
Journal of bioscience and bioengineering, 2019Co-Authors: Toshinori Shimanouchi, Yuki Kitagawa, Yukitaka KimuraAbstract:The properties of the Liposome Membrane as a reaction field were investigated by focusing on the Horner–Wadsworth–Emmons reaction as a case study. Use of the Liposomes existing in the gel phase resulted in the enhanced activity of the substrates and furnished the products with same E/Z stereoselectivity as in the Liposome-free system. The Membrane environment in the gel phase most likely assisted the formation of adducts that induced selective generation of the E-isomer. The possible role of Liposomes is to assist the proton removal from the reactant, rather than providing the basic interfacial environment.
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Membrane interaction between span 80 vesicle and phospholipid vesicle Liposome span 80 vesicle can perturb and hemifuse with liposomal Membrane
Colloids and Surfaces B: Biointerfaces, 2013Co-Authors: Keita Hayashi, Toshinori Shimanouchi, Tsuyoshi Tatsui, Hiroshi UmakoshiAbstract:We have focused on the interaction between the Span 80 vesicle and phospholipid vesicle (Liposome). The Span 80 vesicle was mixed with a phospholipid vesicle (Liposome), used as a simplified model of plasma Membrane. From calcein leakage experiments, it was revealed that the interaction between the Span 80 vesicles and the Liposomes could perturb the Liposome Membrane. In the experiments based on fluorescence resonance energy transfer, the lipid mixing between Span 80 vesicle and Liposome was observed. The above phenomena were also supported by the fluorescence spectroscopic analysis using laurdan, resulting in the variation in the Membrane properties of Liposome after its mixing with Span 80 vesicle. These results suggest that the Span 80 vesicles can easily interact and hemifuse with the Liposome Membrane, which depend on the Membrane properties of the Span 80 vesicle, "flexible" and "molecular structure" of the components.
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secondary nucleation of aβ fibrils on Liposome Membrane
Aiche Journal, 2012Co-Authors: Toshinori Shimanouchi, Nachi Kitaura, Hiroshi Umakoshi, Ryo Onishi, Ryoichi KuboiAbstract:The amyloid fibrils of amyloid β protein (Aβ) from Alzheimer's disease are likely to show the cytotoxicity, depending on their morphology. The relationship between the nucleation kinetics of the Aβ fibrils and their morphology has been investigated. From the perspective of a crystallization technique assuming primary/secondary nucleation steps and an elongation step, the secondary nucleation rate B [# m−3 s−1], was experimentally and coarsely determined by using total internal reflection fluorescence microscopy combined with thioflavin T. In an aqueous solution, linear and rigid fibrils were formed with a relatively smaller B value ((2.83 ± 0.55) × 105 # m−3 s−1), whereas spherulitic amyloid assemblies were formed in the presence of negatively charged Liposome including oxidized lipids, with a larger B value ((7.65 ± 0.47) × 105 # m−3 s−1). Those findings should lead to a better understanding of the mechanism for the formation of fibrils and senile plaques in Alzheimer's disease. © 2012 American Institute of Chemical Engineers AIChE J, 2012
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aβ cu catalyzed oxidation of cholesterol in 1 2 dipalmitoyl phosphatidylcholine Liposome Membrane
Journal of Bioscience and Bioengineering, 2010Co-Authors: Toshinori Shimanouchi, Hiroshi Umakoshi, Makoto Tasaki, Haruyuki Ishii, Noriko Yoshimoto, Ryoichi KuboiAbstract:The amyloid beta protein with 42 amino acid residues (Abeta), which is a causative protein of Alzheimer's disease (AD), forms the complex with copper (II) to induce the cholesterol oxidase-like activity by the proton transfer from the cholesterol. In this study, the oxidation of cholesterol by Abeta/Cu complex was investigated on the surface of the zwitterionic phospholipid Liposome including the bound water advantageous for the enhancement of the proton transfer. The bound water was pooled by the formation of cholesterol-rich domain within Liposomes. The resulting reactivity was enhanced by the proton transfer mediated by the bound water.
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Liposome Membrane can act like molecular and metal chaperones for oxidized and fragmented superoxide dismutase
Enzyme and Microbial Technology, 2009Co-Authors: Le Quoc Tuan, Toshinori Shimanouchi, Hiroshi Umakoshi, Ryoichi KuboiAbstract:Abstract A mechanism for Liposome-recruited activity of oxidized and fragmented superoxide dismutase (Fr.-SOD) [Tuan LQ, Umakoshi H, Shimanouchi T, Kuboi R. Liposome-recruited activity of oxidized and fragmented superoxide dismutase. Langmuir 2008;24:350–4] was further investigated, focusing on the secondary structure of Fr.-SOD. Liposome Membrane was found to assist the conformational change of Fr.-SOD and reactivate the enzymatic activity, like molecular and metal chaperones. The loss of SOD activity and its secondary structure was observed during 6 h oxidation in 2 mM hydrogen peroxide. The contents of the α-helix and β-sheet structures in the oxidized and fragmented SOD (2 μM) were increased only in the presence of 10 μM Cu 2+ and Zn 2+ together, or in the presence of 2 mM POPC Liposomes. The mixture of all of these elements (fragmented SOD and POPC Liposomes with Cu 2+ and Zn 2+ ) gave not only the increase of the α-helix and β-sheet contents but also the mediation of the high SOD-like activity.
Ryoichi Kuboi - One of the best experts on this subject based on the ideXlab platform.
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secondary nucleation of aβ fibrils on Liposome Membrane
Aiche Journal, 2012Co-Authors: Toshinori Shimanouchi, Nachi Kitaura, Hiroshi Umakoshi, Ryo Onishi, Ryoichi KuboiAbstract:The amyloid fibrils of amyloid β protein (Aβ) from Alzheimer's disease are likely to show the cytotoxicity, depending on their morphology. The relationship between the nucleation kinetics of the Aβ fibrils and their morphology has been investigated. From the perspective of a crystallization technique assuming primary/secondary nucleation steps and an elongation step, the secondary nucleation rate B [# m−3 s−1], was experimentally and coarsely determined by using total internal reflection fluorescence microscopy combined with thioflavin T. In an aqueous solution, linear and rigid fibrils were formed with a relatively smaller B value ((2.83 ± 0.55) × 105 # m−3 s−1), whereas spherulitic amyloid assemblies were formed in the presence of negatively charged Liposome including oxidized lipids, with a larger B value ((7.65 ± 0.47) × 105 # m−3 s−1). Those findings should lead to a better understanding of the mechanism for the formation of fibrils and senile plaques in Alzheimer's disease. © 2012 American Institute of Chemical Engineers AIChE J, 2012
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aβ cu catalyzed oxidation of cholesterol in 1 2 dipalmitoyl phosphatidylcholine Liposome Membrane
Journal of Bioscience and Bioengineering, 2010Co-Authors: Toshinori Shimanouchi, Hiroshi Umakoshi, Makoto Tasaki, Haruyuki Ishii, Noriko Yoshimoto, Ryoichi KuboiAbstract:The amyloid beta protein with 42 amino acid residues (Abeta), which is a causative protein of Alzheimer's disease (AD), forms the complex with copper (II) to induce the cholesterol oxidase-like activity by the proton transfer from the cholesterol. In this study, the oxidation of cholesterol by Abeta/Cu complex was investigated on the surface of the zwitterionic phospholipid Liposome including the bound water advantageous for the enhancement of the proton transfer. The bound water was pooled by the formation of cholesterol-rich domain within Liposomes. The resulting reactivity was enhanced by the proton transfer mediated by the bound water.
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Liposome Membrane can act like molecular and metal chaperones for oxidized and fragmented superoxide dismutase
Enzyme and Microbial Technology, 2009Co-Authors: Le Quoc Tuan, Toshinori Shimanouchi, Hiroshi Umakoshi, Ryoichi KuboiAbstract:Abstract A mechanism for Liposome-recruited activity of oxidized and fragmented superoxide dismutase (Fr.-SOD) [Tuan LQ, Umakoshi H, Shimanouchi T, Kuboi R. Liposome-recruited activity of oxidized and fragmented superoxide dismutase. Langmuir 2008;24:350–4] was further investigated, focusing on the secondary structure of Fr.-SOD. Liposome Membrane was found to assist the conformational change of Fr.-SOD and reactivate the enzymatic activity, like molecular and metal chaperones. The loss of SOD activity and its secondary structure was observed during 6 h oxidation in 2 mM hydrogen peroxide. The contents of the α-helix and β-sheet structures in the oxidized and fragmented SOD (2 μM) were increased only in the presence of 10 μM Cu 2+ and Zn 2+ together, or in the presence of 2 mM POPC Liposomes. The mixture of all of these elements (fragmented SOD and POPC Liposomes with Cu 2+ and Zn 2+ ) gave not only the increase of the α-helix and β-sheet contents but also the mediation of the high SOD-like activity.
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Liposome Membrane itself can affect gene expression in the escherichia coli cell free translation system
Langmuir, 2008Co-Authors: Huong Thi Bui, Toshinori Shimanouchi, Hiroshi Umakoshi, Kien Xuan Ngo, Masato Nishida, Ryoichi KuboiAbstract:A possible role of a model bioMembrane, Liposome, in gene expression was investigated by using the cell-free translation system. A reporter protein, green fluorescence protein (GFP), was expressed in vitro with and without Liposome prepared with 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphatidyl chorine (POPC) and cholesterol (Ch) (5.7 mM lipid concentration). In the presence of POPC/Ch Liposome, the fluorescence intensity of produced GFP was found to be 1.67 times higher than that in the control after 18 h of expression. The results of the SDS-PAGE analysis also show the above promotion effect of the Liposome on the net expression of the GFP gene (1.58 times more). The amounts of mRNA were found to be promoted to 1.29 times higher than those in the control. The differences among mRNA, net expression of the GFP gene, and GFP fluorescence indicate that the enhanced GFP expression in the presence of POPC/Ch Liposome could primarily affect the transcription and translation of the GFP gene among the possible step...
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Fluorescence study on the domain formation of N -dodecanoyl- l -tryptophan within a Liposome Membrane
Colloid and Polymer Science, 2006Co-Authors: Kazuma Yasuhara, Toshinori Shimanouchi, Hiroshi Umakoshi, Ryoichi KuboiAbstract:The aggregation behavior of N-dodecanoyl-l-tryptophan within a Liposome Membrane was investigated by fluorescence spectroscopy. Liposomes with a mean diameter of 100 nm, formed from either 1-2-dilauroyl-sn-glycero-3-phosphocholine, 1-2-myristoyl-sn-glycero-3-phosphocholine, or 1-2-palmitoyl-sn-glycero-3-phosphocholine, were used. Fluorescence measurements indicate that the sodium salt of N-dodecanoyl-l-tryptophan forms domains with the Liposome Membranes below the main phase transition temperature, T m. Above T m, the molecules are homogeneously dispersed in the liquid crystalline state of the Membranes.
Allen J Bard - One of the best experts on this subject based on the ideXlab platform.
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Lipid Membrane Permeability of Synthetic Redox DMPC Liposomes Investigated by Single Electrochemical Collisions
Analytical Chemistry, 2020Co-Authors: Estelle Lebègue, Frédéric Barrière, Allen J BardAbstract:The electrochemical detection of synthetic redox DMPC (1,2-dimyristoyl-sn-glycero-3-phosphocholine) Liposomes by single collisions at 10 μm diameter carbon and Pt ultramicroelectrodes (UMEs) is reported. To study the parameters influencing the lipid Membrane opening/permeability, the electrochemical detection of single redox DMPC Liposome collisions at polarized UMEs was investigated under different experimental conditions (addition of surfactant, temperature). The electrochemical responses recorded showed that the permeability of the DMPC lipid Membrane (tuned by addition of Triton X-100 surfactant or by the increase of the solution temperature) is a key parameter for the Liposome Membrane electroporation process and hence for the release and oxidation of its redox content during the collision onto UMEs. The presence of ferrocenemethanol as an additional redox probe in the aqueous solution (at room temperature and without addition of surfactant) is also an interesting strategy to detect current spikes corresponding to single redox DMPC Liposome collisions with KFe(CN)/KFe(CN) as the encapsulated aqueous redox probe.
Takaaki Ishigami - One of the best experts on this subject based on the ideXlab platform.
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Chiral Selective Adsorption of Ibuprofen on a Liposome Membrane
The journal of physical chemistry. B, 2016Co-Authors: Yukihiro Okamoto, Yusuke Kishi, Takaaki Ishigami, Keishi Suga, Hiroshi UmakoshiAbstract:We investigated the key factors that affect enantioselective adsorption of ibuprofen (IBU) on a Liposome Membrane by changing its lipid composition: the Liposome Membrane shows different Membrane fluidity, surface charge, content of chiral components, and heterogeneity (nanodomain). Nonspecific interactions (hydrophobic and electrostatic) were revealed to be an important factor in enhancing the adsorbed amount of IBU, based on adsorption experiments carried out using single lipids (DPPC, DMPC, DOPC, and DLPC) and positively charged Liposomes (DOTAP and Liposome containing DC-Ch). Furthermore, control of the boundary edge (i.e., the nanodomain size) derived from the Membrane heterogeneity was important for enantioselective adsorption; as well as multiple weak interactions between lipid molecules and IBU enantiomers. The above findings provided a good index for constructing liposomal chiral adsorbents.
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Liposome Membrane as a Platform for the L-Pro-Catalyzed Michael Addition of trans-β-Nitrostyrene and Acetone.
Langmuir : the ACS journal of surfaces and colloids, 2015Co-Authors: Masanori Hirose, Keishi Suga, Takaaki Ishigami, Hiroshi UmakoshiAbstract:Herein, we show that the l-proline (l-Pro)-catalyzed Michael addition of trans-β-nitrostyrene and acetone can proceed in “water” using Liposome Membranes and that the Membrane fluidity and polarity are major controlling factors for this reaction. The highest conversion and rate constant of the reaction within the Liposomes was achieved with the 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC)/1,2-dipalmitoyl-3-trimethylammoniumpropane (DPTAP) system. The catalytic activity of l-Pro in the Liposome suspension was found to be comparable to that in a DMSO system. The reaction rate constant was found to be controlled by both the phase state of the Liposome Membrane and the surface charge on the Membrane. Greater enantioselectivity was achieved in the presence of the Liposomes than in DMSO solution, with corresponding enantiomeric excess values of 97.6% for the DOPC/DPTAP Liposome system and 10% in DMSO. The hydrophobic region of the Liposome Membrane, which is a relatively stable self-organizing system, can se...
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Homochiral oligomerization of L-histidine in the presence of Liposome Membranes
Colloid and Polymer Science, 2015Co-Authors: Takaaki Ishigami, Yukihiro Okamoto, Keishi Suga, Yoshinori Kaneko, Hiroshi UmakoshiAbstract:We report about a novel method for the homochiral oligomerization of l-amino acids in the presence of Liposomes. For this homochiral oligomerization, we took advantage of the superior properties of Liposomes as chiral adsorbent, concentrator of reacting molecules, and as effective reaction medium. Indeed, Liposomes composed of l-phospholipids could enantioselectively bind and concentrate only l-histidine (l-His) on the Liposome Membrane, and not D-His, which was confirmed by UV measurements. Furthermore, we demonstrate that the Liposomes enabled effective oligomerization of l-His on or in the Liposome Membrane, while the oligomerization of d-His in the Liposome system—or in absence of Liposomes—was less efficient. The experimental findings are supported by logP value calculations. These calculations indicate that activated intermediates locate in the center of the bilayer where they are protected from hydrolysis due to the hydrophobic environment of the Liposome Membrane. Therefore, the use of Liposomes from l-phospholipids enables homochiral oligomerization and more efficient oligomerization of l-amino acids as compared to d-amino acids. Thus, our developed method could be used for the synthesis of homochiral polymers from racemic mixtures of monomers and may contribute to the understanding of prebiotic biopolymer formation.
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Comparison of Partitioning Behaviors of L-/D-Trpin Solvent-Water System and Liposome Membrane System
Solvent Extraction Research and Development Japan, 2013Co-Authors: Takaaki Ishigami, Hiroshi UmakoshiAbstract:The partitioning behaviors of L-/D-Trp in a solvent-water system modified with a phospholipid and a Liposome Membrane system were compared. Trp was partitioned to the interface of chloroform-water system supplemented with phospholipid. As the methanol ratio in the chloroform phase increased, the Trp was gradually partitioned to the organic phase while the chiral selectivity (the partitioning ratio of L-/D-Trp) was not increased. In contrast, the Liposome Membrane system was found to induce a significant chiral selectivity of L-Trp against D-Trp during their partitioning from the aqueous phase to the lipid Membrane. This result clearly indicates the significance of the Liposome Membrane, a self-assembly of higher molecular order, as an effective platform for selective separation (or recognition).
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comparison of partitioning behaviors of l d trpin solvent water system and Liposome Membrane system
Solvent Extraction Research and Development-japan, 2013Co-Authors: Takaaki Ishigami, Hiroshi UmakoshiAbstract:The partitioning behaviors of L-/D-Trp in a solvent-water system modified with a phospholipid and a Liposome Membrane system were compared. Trp was partitioned to the interface of chloroform-water system supplemented with phospholipid. As the methanol ratio in the chloroform phase increased, the Trp was gradually partitioned to the organic phase while the chiral selectivity (the partitioning ratio of L-/D-Trp) was not increased. In contrast, the Liposome Membrane system was found to induce a significant chiral selectivity of L-Trp against D-Trp during their partitioning from the aqueous phase to the lipid Membrane. This result clearly indicates the significance of the Liposome Membrane, a self-assembly of higher molecular order, as an effective platform for selective separation (or recognition).