• Title/Summary/Keyword: Phospholipid membranes

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Effects of Brazilin on Lipid and Phosphatidyl Fatty Acid Composition of Erythrocyte Membrane in Streptozotocin-induced Diabetic Rats

  • Moon, Change-Kiu;Yoon, Eun-Yi;Lee, Soo-Hwan;Moon, Chang-hyun;Hwang, Daniel-H.
    • Archives of Pharmacal Research
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    • v.16 no.2
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    • pp.147-151
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    • 1993
  • In diabetes, the abnormal increase of the membrane cholesterol/phospholipid ratio (C/PL) is consdered to be the main reason for the decreased membrane fluidity, which then results in impaired erythrocyte deformability and subsequent microcirculatory disturbances. In this study, we examined the effects of brazilin on lipid and phosphatidyl fatty acid composition of erythrocyte membranes in streptozotocin induced diabetic rats. Treatment of brazilin (10mg/kg or 100 mg/kg for 2 weeks, i.p) altered and cholesterol contents in diabetic erythrocyte membranes. The C/PL ratio of brazilin treated groups decreased compared with that of diabetic control group while no change was observed in normal erythrocytes. In streptozotocin induced diabetic rats, alterations in phosphatidyl fatty acid compositioin of erythrocyte membranes were observed and brazilin could reverse these alterations. Arachidonic acid level reumed to a normal level while linoleic acid level remained unchanged by the treatment of brazilin. The results suggest that brazilin might increase erythrocyte membrane fluidity which plays a key role inregulating erythrocyte deformability, thereby it could exert positive effects on microdiculatory disturbances.

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Degradation of Phospholipids of Yeast after Freeze-Thawing

  • Hahn, Young-Sook
    • Preventive Nutrition and Food Science
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    • v.1 no.2
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    • pp.252-255
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    • 1996
  • As an index of freeze-injury of yeast, the leakage of intracellular substances from yeast cells after freeze-thawing was investigated. It was found that much more ultraviolet-absorbing substances leaked out from non-freeze tolerant yeast (NETY) than from freeze-tolerant yeast. Furthermore, the rate of leakage of cellular substances form NFTY during incubation exceeded that of FTY, indicating that NFTY is more susceptible to freeze-injury than FTY during frozen-storage. An apparent degradation of phospholipid was observed during incubation of perfermented frozen-cells of NFTY, while little change of phospholipid occurred in FTY, These results suggested that the difference in the sensitivity of yeast might be due to the strength of cell membrane in terms of the degradation of phospholipid by enzymes, phospholipases, attached to cell membranes.

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Research Method of Fatty Acids Transfer between Phospholipid Model Membranes (인지질 모델막에서의 지방산 이동에 관한 연구 방법)

  • 임병순;김혜경;김을상
    • Journal of the Korean Society of Food Science and Nutrition
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    • v.26 no.4
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    • pp.743-750
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    • 1997
  • Direct measurement of the kinetics of free fatty acid transfer between phospholipid model membrane is technically limited by the rapid nature of the transfer process. Separation of membrane-bound fatty acid by centrifugation has shown that although the equilibrium distribution of free fatty acid is determined by this method, fatty acid transfer occurs too rapidly for accurate kinetic measurements. Recently fluorescence resonance energy transfer(FRET) assay has been developed to examine transfer of fatty acids between membranes. Donor membranes which has fluorescent fatty acid, anthroyloxy fatty acid(AOFA), is mixed with acceptor membranes which has non-interchangeable fluorescent quencher, nitrobenzo-xadiazol(NBD), using stopped flow apparatus. As the fluorescent fatty acids transfer from donor membrane to acceptor membrane, fluorescence intensity would be decreased and the rate and degree of fatty acid transfer can be analyzed. Fatty acid transfer between micelles is more complicated because of bile salt. Therefore in experiments with micelles, fluorescence self quenching assay is used. At high concentrations, a fluorophore tends to quench its own fluorescence causing a reduction in fluorescence intensity. Donor micelles contained self quenching concentrations of fluorophore and acceptor micelles had no fluorophore. Upon mixing of donor and acceptor micelles, the rate of transfer of the fluorophore from the donor to the acceptor was measured by monitoring the release in self quenching when its concentration in donor decreased over time.

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Determination of Saturated and Unsaturated Fatty Acids Amount in Leukocyte Membranes from Subjects Fed with Solid and Fluid Oils

  • Erman, Fazilet;Aydin, Suleyman;Demir, Yasar;Akcay, Fatih;Bakan, Ebubekir
    • BMB Reports
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    • v.39 no.5
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    • pp.516-521
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    • 2006
  • Modifications in dietary fatty acid intake might lead to a modification in membrane phospholipid fatty acid composition. The purpose of this study was to investigate relationship between different type of oil consumption and leukocyte membrane phospholipid composition. This study was carried out in subjects utilizing butter (n = 15), margarine (n = 15), fluid oil (n = 15) and mixed types of oils (n = 15) in total 60 subjects. Leukocytes were separated from total blood by dextran sedimentation method. Membrane lipids and proteins were isolated following the cell disruption. Fatty acids of membrane phospholipids were isolated by hydrolysation with phospholipase B under ultrasonic dismembranator. Free fatty acids were identified with gas chromatography at chloroform phase. The results obtained were compared with data obtained by chromatograms of the standards. Results more prominent values of arachidic, dihomo-$\gamma$-linolenic and palmitoleic acids were found in butter-or mixed oil-user groups; eicosadienoic, eicosamonoenoic, dihomo-$\gamma$-linolenic and behenic acids in fluid oil; heptanoic, valeric, eicosadienoic and linolenic acids in margarine groups. The fatty acid composition of mixed oil was similar to butter, while other two oils were so different. From this study, it was concluded that the type of oil consumption might have an influence on phospholipid components of plasma membranes.

Effect of Dietary Fat on Structure and Function of Mammalian Cell Membrane (식이지방이 생체막 구조와 기능에 미치는 영향)

  • Cho, Sung-Hee
    • Journal of the Korean Society of Food Science and Nutrition
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    • v.13 no.4
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    • pp.459-468
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    • 1984
  • The currently accepted model of membrane structure proposes a dynamic, asymmetric lipid matrix of phospholipids and cholesterol with globular proteins embedded across the membrane to various degrees. Most phospholipids are in the bilayer arrangement and also closely associated with integral membrane proteins or loosely associated with peripheral proteins. Biological functions of membrane, such as membrane-bound enzyme functions and transport systems, are influenced by the membrane physical properties, which are determined by fatty acid composition of phospholipids, polar head group composition and membrane cholesterol content. Polar and non-polar region of the phospholipid molecule can interact, with changes in the conformation of a membrane-associated protein altering either its catalytic activity or the protein's interaction with other membrane proteins. Mammalian dietary studies attempted to change the lipid composition of a few cell membranes have shown comparisons, using essential fatty acid-deficient diets. In recent years, Clandinin and a few other workers have pioneered the study proving the influence of dietary fat fed in a nutritionally complete diet on composition of phospholipid classes of cell membrane. Modulation caused by diet fat was rapid and reversible in phospholipid fatty acyl composition of membranes of cardiac mitochondria, liver cell, brain synaptosome and lymphocytes. These changes were at the same time, accompanied by variety of membrane associated functions controlled by membrane-bound enzymes, tranporter and receptor proteins. The findings suggest the basic concept of the necessity of dietary fatty acid balance if consistency of optimal membrane structural lipid composition is to be maintained, as well as the overall inadequacy of describing the nutritional-biochemical quality of a dietary fat solely by its content of linoleic acid. Furthermore, they give light on the possible application to clinical and preventive medicine.

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Structure and Bacterial Cell Selectivity of a Fish-Derived Antimicrobial Peptide, Pleurocidin

  • Yang Ji-Young;Shin Song-Yub;Lim Shin-Saeng;Hahm Kyung-Soo;Kim Yang-Mee
    • Journal of Microbiology and Biotechnology
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    • v.16 no.6
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    • pp.880-888
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    • 2006
  • Pleurocidin, an $\alpha$-helical cationic antimicrobial peptide, was isolated from skin mucosa of winter flounder (Pleuronectes americamus). It had strong antimicrobial activities against Gram-positive and Gram-negative bacteria, but had very weak hemolytic activity. The Gly$^{13,17}\rightarrow$Ala analog (pleurocidin-AA) showed similar antibacterial activities, but had dramatically increased hemolytic activity. The bacterial cell selectivity of pleurocidin was confirmed through the membrane-disrupting and membrane-binding affinities using dye leakage, tryptophan fluorescence blue shift, and tryptophan quenching experiments. However, the non-cell-selective antimicrobial peptide, pleurocidin-AA, interacts strongly with both negatively charged and zwitterionic phospholipid membranes, the latter of which are the major constituents of the outer leaflet of erythrocytes. Circular dihroism spectra showed that pleurocidin-AA has much higher contents of $\alpha$-helical conformation than pleurocidin. The tertiary structure determined by NMR spectroscopy showed that pleurocidin has a flexible. structure between the long helix from $Gly^3$ to $Gly^{17}$ and the short helix from $Gly^{17}$ to $Leu^{25}$. Cell-selective antimicrobial peptide pleurocidin interacts strongly with negatively charged phospholipid membranes, which mimic bacterial membranes. Structural flexibility between the two helices may play a key role in bacterial cell selectivity of pleurocidin.

Structural and Functional Characterization of CRAMP-18 Derived from a Cathelicidin-Related Antimicrobial Peptide CRAMP

  • Park, Kyong-Soo;Shin, Song-Yub;Hahm, Kyung-Soo;Kim, Yang-Mee
    • Bulletin of the Korean Chemical Society
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    • v.24 no.10
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    • pp.1478-1484
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    • 2003
  • CRAMP was identified from a cDNA clone derived from a mouse femoral marrow cells as a member of cathelicidin-derived antimicrobial peptide. Tertiary structure of CRAMP in TFE/$H_2O$ (1 : 1, v/v) solution has been determined by NMR spectroscopy previously and consists of two amphipathic $\alpha-helices$ from Leu4 to Lys10 and from Gly16 to Leu33. These two helices are connected by a flexible region from Gly11 to Gly16. Analysis of series of fragments composed of various portion of CRAMP revealed that an 18-residue fragment with the sequence from Gly16 to Leu33 (CRAMP-18) was found to retain antibacterial activity without cytotoxicity. The effects of two Phe residues at positions 14 and 15 of CRAMP-18 on structure, antibacterial activity, and interaction with lipid membranes were investigated by $Phe^{14,15}$ ${\rightarrow}$ Ala substitution (CRAMP-18-A) in the present study. Substitution of Phe with Ala in CRAMP-18 caused a significant reduction on antibacterial and membrane-disrupting activities. Tertiary structures of CRAMP-18 in 50% TFE/$H_2O$ (1 : 1, v : v) solution shows amphipathic ${\alpha}$-helix, from $Glu^2{\;}to{\;}Leu^{18}$, while CRAMP-18-A has relatively short amphipathic ${\alpha}$-helix from $Leu^4{\;}to{\;}Ala^{15}$. These results suggest that the hydrophobic property of $Phe^{14}{\;}and{\;}Phe^15$ in CRAMP-18 is essential for its antibacterial activity, ${\alpha}$-helical structure, and interactions with phospholipid membranes.

Effect of Trehalose on Biological Membranes with Respect to Phase of the Membranes

  • Park, Jin-Won
    • KSBB Journal
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    • v.32 no.2
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    • pp.103-107
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    • 2017
  • The effect of the trehalose incorporation on the biological membranes was investigated with respect to the phase of the membranes using the fluorescence intensity change. Spherical phospholipid bilayers, vesicles, were prepared only with the variation in the phase of each layer via a double emulsion technique. In the aqueous inside of the vesicles, 8-Aminonaphthalene-1,3,6-trisulfonic acid disodium salt(ANTS) was encapsulated. As a quencher, p-Xylene-bis(N-pyridinium bromide)(DPX) was included in the buffer where the vesicles were dispersed. The fluorescence scale was calibrated with the fluorescence of ANTS vesicles in p-Xylene-bis(N-pyridinium bromide)(DPX)-included-buffer taken as 100% fluorescence and the mixture of ANTS and DPX in the buffer as 0% fluorescence. Trehalose injection into the vesicle solution led the distortion of the membrane. It was found that the distortion was related to the phase of each layer the vesicle up on the ratio of trehalose to lipid. In the identical measurements at glucose, the behavior of the distortion was completely different from that of trehalose. These results seem to depend on the stability of the vesicles, due to the osmotic and volumetric effects on the headgroup packing disruption.

Mechanism of Fatty Acid Transfer between Fatty Acid Binding Proteins and Phospolipid Model Membranes (지방산 결합단백질과 인지질막 사이의 지방산이동기전)

  • 김혜경
    • Journal of Nutrition and Health
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    • v.30 no.8
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    • pp.930-935
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    • 1997
  • Fatty acid binging proteins(FABP) are distinct but related gene productes which are found in many mamalian cell types. FABP bind long chain fatty acids in vitro. However, their functions and mechanisms of action, in vivo, remain unknown . Also not known is whether all FABP function similaryly in their respective cell types. or whether different FABP have unique functions. The puropose of the present study was to assess whether different members of the FABP family exhibit different structural and function properties. A comparison was made between heart(H-FABP) and liver (L-FABP). The results show that the binding sites of both FABP are hydrophobic in nature, although the L-FABP site is more nonpolar than the H-FABP site. Additionally, the bound ligand experiences less motional constraint within the H-FABP binding site than within the L-FABP binding site. In accordance with these differences in structural properties, it was found that anthroyloxy-fatty acid transfer from H-FABP to membranes is markedly faster than from L-FABP. moreover, the mechanism of fatty acid transfer to phospholipid membranes appears to occur via transient collisional interactions between H-FABP and membranes. In contrast , transfer of fatty acid from L-FABP occurs via an aqueous diffusion mechanism.

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A Study on the Orientational properties of Phospholipid Monolayers (지질단분자막의 배향 특성에 관한 연구)

  • Lee, Kyung-Sup;Kwon, Young-Soo
    • Proceedings of the KIEE Conference
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    • 1995.07c
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    • pp.1217-1219
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    • 1995
  • The organization of phospholipid monolayers on a water surface was investigated by means of Maxwell-Displacement-Current(MDC)-Measuring technique. The phase transition from the gaseous phase to the gaseous-fluid phase which accompanies the polar ordering of lipid molecules was detected by the technique in the range of immeasurable low surface pressure and the molcular-area which gives the onset of the transition was determined for lipid monolayers. The vertical component of dipole moment of lipid membranes was determined from the charge flowing the rough the circuit, and we measured differential themal analysis of sample.

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