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Wyszukujesz frazę "lipid bilayer" wg kryterium: Temat


Wyświetlanie 1-5 z 5
Tytuł:
Physical properties of lipid bilayer membranes: relevance to membrane biological functions.
Autorzy:
Subczynski, Witold
Wisniewska, Anna
Powiązania:
https://bibliotekanauki.pl/articles/1044298.pdf
Data publikacji:
2000
Wydawca:
Polskie Towarzystwo Biochemiczne
Tematy:
lipid exchange
hydrophobic barrier
oxygen transport
lipid unsaturation
membrane domains
lipid bilayer
Opis:
Over the last 25 years one of us (WKS) has been investigating physical properties of lipid bilayer membranes. In 1991 a group led by WKS was organized into the Laboratory of Structure and Dynamics of Biological Membranes, the effective member of which is AW. Using mainly the electron paramagnetic resonance (EPR) spin-labeling method, we obtained unexpected results, which are significant for the better understanding of the functioning of biological membranes. We have developed a new pulse EPR spin-labeling method for the detection of membrane domains and evaluation of lipid exchange rates. This review will be focused on our main results which can be summarized as follows: (1) Unsaturation of alkyl chains greatly reduces the ordering and rigidifying effects of cholesterol although the unsaturation alone gives only minor fluidizing effects, as observed by order and reorientational motion, and rather significant rigidifying effects, as observed by translational motion of probe molecules; (2) Fluid-phase model membranes and cell plasma membranes are not barriers to oxygen and nitric oxide transport; (3) Polar carotenoids can regulate membrane fluidity in a way similar to cholesterol; (4) Formation of effective hydrophobic barriers to the permeation of small polar molecules across membranes requires alkyl chain unsaturation and/or the presence of cholesterol; (5) Fluid-phase micro-immiscibility takes place in cis-unsaturated phosphatidylcholine-cholesterol membranes and induces the formation of cholesterol-rich domains; (6) In membranes containing high concentrations of transmembrane proteins a new lipid domain is formed, with lipids trapped within aggregates of proteins, in which the lipid dynamics is diminished to the level of gel-phase.
Źródło:
Acta Biochimica Polonica; 2000, 47, 3; 613-625
0001-527X
Pojawia się w:
Acta Biochimica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Carotenoid - membrane interactions in liposomes: effect of dipolar, monopolar, and nonpolar carotenoids
Autorzy:
Wisniewska, Anna
Widomska, Justyna
Subczynski, Witold
Powiązania:
https://bibliotekanauki.pl/articles/1041203.pdf
Data publikacji:
2006
Wydawca:
Polskie Towarzystwo Biochemiczne
Tematy:
macular xanthophylls
β-cryptoxanthin
β-carotene
lutein
spin labeling
AMD
EPR
lipid bilayer
Opis:
Electron paramagnetic resonance (EPR) spin-labeling methods were used to study the effects of carotenoids on the physical properties of saturated phosphatidylcholine (PC) membranes to evaluate the contribution of the terminal hydroxyl groups of xanthophyll molecules to the carotenoid-membrane interaction. Effects of the dipolar, terminally dihydroxylated carotenoid lutein on membrane phase transition, fluidity, order, and polarity were compared with those of monopolar (β-cryptoxanthin) and nonpolar (β-carotene) carotenoids. These effects were monitored at the membrane center as a function of the amount of the carotenoid added to the sample and as a function of temperature for fluid-phase membranes. PC membranes with different thickness (from 12 to 22 carbons in alkyl chains) were used. Carotenoids shifted to lower temperatures and broadened the main phase transition of PC membranes. They decreased the membrane fluidity and increased the order of alkyl chains. Carotenoids also increased the hydrophobicity of the membrane interior. These effects were the strongest for lutein, significantly weaker for β-cryptoxanthin, and negligible for β-carotene. They decreased with the increase of the membrane thickness. Presented results suggest that anchoring of carotenoid molecules at the opposite membrane surfaces by polar hydroxyl groups is significant in enhancing their effects on membrane properties. This manuscript also shows the ability of EPR spin-labeling methods to monitor different membrane properties that can be applied in biotechnological studies with the use of liposomes.
Źródło:
Acta Biochimica Polonica; 2006, 53, 3; 475-484
0001-527X
Pojawia się w:
Acta Biochimica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The effect of hexadecaprenol on molecular organisation and transport properties of model membranes.
Autorzy:
Janas, Teresa
Nowotarski, Krzysztof
Gruszecki, Wiesław
Janas, Tadeusz
Powiązania:
https://bibliotekanauki.pl/articles/1044307.pdf
Data publikacji:
2000
Wydawca:
Polskie Towarzystwo Biochemiczne
Tematy:
voltammetric studies.
bilayer lipid membranes
Langmuir film studies
long-chain polyprenol
lipid monolayer
Opis:
The Langmuir monolayer technique and voltammetric analysis were used to investigate the properties of model lipid membranes prepared from dioleoylphosphatidylcholine (DOPC), hexadecaprenol (C80), and their mixtures. Surface pressure- molecular area isotherms, current-voltage characteristics, and membrane conductance-temperature were measured. Molecular area isobars, specific molecular areas, excess free energy of mixing, collapse pressure and collapse area were determined for lipid monolayers. Membrane conductance, activation energy of ion migration across the membrane, and membrane permeability coefficient for chloride ions were determined for lipid bilayers. Hexadecaprenol decreases the activation energy and increases membrane conductance and membrane permeability coefficient. The results of monolayer and bilayer investigations show that some electrical, transport and packing properties of lipid membranes change under the influence of hexadecaprenol. The results indicate that hexadecaprenol modulates the molecular organisation of the membrane and that the specific molecular area of polyprenol molecules depends on the relative concentration of polyprenols in membranes. We suggest that hexadecaprenol modifies lipid membranes by the formation of fluid microdomains. The results also indicate that electrical transmembrane potential can accelerate the formation of pores in lipid bilayers modified by long chain polyprenols.
Źródło:
Acta Biochimica Polonica; 2000, 47, 3; 661-673
0001-527X
Pojawia się w:
Acta Biochimica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Physicochemical analysis of phosphatidylcholine-ceramide system in bilayer lipid membranes
Autorzy:
Naumowicz, Monika
Petelska, Aneta
Figaszewski, Zbigniew
Powiązania:
https://bibliotekanauki.pl/articles/1040678.pdf
Data publikacji:
2008
Wydawca:
Polskie Towarzystwo Biochemiczne
Tematy:
equilibrium
ceramide
complex formation
electrochemical impedance spectroscopy
phosphatidylcholine
bilayer lipid membrane
Opis:
Electrochemical impedance spectroscopy was used for the study of two-component lipid membranes. Phosphatidylcholine and ceramide were to be investigated, since they play an important biochemical role in cell membranes. The research on biolipid interaction was focused on quantitative description of processes that take part in a bilayer. Assumed models of interaction between amphiphilic molecules and the equilibria that take place there were described by mathematical equations for the studied system. The possibility of complex formation for two-component system forming bilayers was assumed that could explain the deviation from additivity rule. Equilibria were described by mathematical equations that were further verified experimentally. The determined values of parameters (stability constant, molecular area of complex, capacitance and conductance of the lipid membranes formed from molecules and complexes) were used for calculation of model curves. The comparison of model curves and experimental points verified the assumed model.
Źródło:
Acta Biochimica Polonica; 2008, 55, 4; 721-730
0001-527X
Pojawia się w:
Acta Biochimica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Zastosowanie spektroskopii oscylacyjnej w zakresie nir do śledzenia modyfikacji konformacyjnych zachodzących w hydrofobowym obszarze modelowych dwuwarstw lipidowych
Application of nir range vibrational spectroskopy to follow the conformational modifications occuring in the hydrophobic region of model lipid bilayers
Autorzy:
Kuć, Marta
Cieślik-Boczula, Katarzyna
Rospenk, Maria
Powiązania:
https://bibliotekanauki.pl/articles/27310038.pdf
Data publikacji:
2023
Wydawca:
Polskie Towarzystwo Chemiczne
Tematy:
dwuwarstwa lipidowa
liposom
główne przejście fazowe
spektroskopia oscylacyjna w zakresie średniej podczerwieni (MIR)
spektroskopia oscylacyjna w zakresie bliskiej podczerwieni (NIR)
Analiza Składników Głównych (PCA)
lipid bilayer
liposome
main phase transition
Mid-infrared vibrational spectroscopy (MIR)
Near-infrared vibrational spectroscopy (NIR)
Principal Component Analysis (PCA)
Opis:
Biomembranes, which are the structural and functional basis of the cells of all living organisms, have been an extremely interesting research object for biology and chemistry scientists for years. The multitude of elements constituting the components of natural lipid membranes, however, is associated with interpretation difficulties regarding the nature of the processes taking place in them. A useful research object that is a model of bilamellar biosystems with a significantly simplified composition and at the same time retaining properties that can be a reference point in relation to natural membranes are lipid membranes in the form of one or several component liposomes. It is precisely such systems built of molecules of dipalmitoyl phosphatidylcholine (DPPC) or dipalmitoyl phosphatidylglycerol (DPPG), and analogous systems with the addition of cholesterol (Chol), that were the subject of research in this work. Near-infrared (NIR) vibrational spectroscopy provides a suitable method for the study of the hydrated samples. In most cases it can be alternatively adopted instead of commonly used mid-infrared (MIR) vibrational spectroscopy. This technique was applied for the first time to identify the spectral changes associated with the conformational changes in the hydrophobic region of model lipid bilayers. Trans/gauche isomerization of CH2 groups of lipid hydrocarbon chains is accompanied by characteristic changes in spectral parameters of both νas,s CH2 bands and their first overtones (2νas,s CH2). The heating of all types of analyzed liposomes results in main phase transition (Tm) accompanied by trans to gauche isomerization of CH2 groups of lipid hydrocarbon chains. The NIR-spectroscopy was able to describe in proper way (similar to MIR results) the character of Tm in studied bilayers.
Źródło:
Wiadomości Chemiczne; 2023, 77, 7-8; 647--686
0043-5104
2300-0295
Pojawia się w:
Wiadomości Chemiczne
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-5 z 5

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