Spin-label studies of bile salt micelles

Kawamura, Hideo; Murata, Yoshinori; Yamaguchi, Takeo; Igimi, Hirotsune; Tanaka, Mitsuru; Sugihara, Gohsuke; Kratohvil, J. P.

doi:10.1021/j100345a087

Cited by 163 publications

(154 citation statements)

References 3 publications

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“…Three models have been proposed: primary micelles, which are formed at low detergent concentration, having a disk shaped structure with one or two bile salt layers (model I) [31][32][33], and at higher detergent concentration, secondary micelles, where the aggregates are stabilised via hydrogen bondings between different primary micelles. Kawamura et al [34] have proposed another model, where the aggregates form a disk shaped structure with a single bile salt layer (model II). In contrast, other results [35,36] suggest a helical structure (model III) with counter ions and water on the axis of a helix.…”

Section: Compartment Concentrationmentioning

confidence: 99%

Membranolytic Activity of Bile Salts: Influence of Biological Membrane Properties and Composition

et al. 2007

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Abstract:The two main steps of the membranolytic activity of detergents: 1) the partitioning of detergent molecules in the membrane and 2) the solubilisation of the membrane are systematically investigated. The interactions of two bile salt molecules, sodium cholate (NaC) and sodium deoxycholate (NaDC) with biological phospholipid model membranes are considered. The membranolytic activity is analysed as a function of the hydrophobicity of the bile salt, ionic strength, temperature, membrane phase properties, membrane surface charge and composition of the acyl chains of the lipids. The results are derived from calorimetric measurements (ITC, isothermal titration calorimetry). A thermodynamic model is described, taking into consideration electrostatic interactions, which is used for the calculation of the partition coefficient as well as to derive the complete thermodynamic parameters describing the interaction of detergents with biological membranes (change in enthalpy, change in free energy, change in entropy etc). The solubilisation properties are described in a so-called vesicle-to-micelle phase transition diagram. The obtained results are supplemented and confirmed by data obtained from other biophysical techniques (DSC differential scanning calorimetry, DLS dynamic light scattering, SANS small angle neutron scattering).

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Section: Compartment Concentrationmentioning

confidence: 99%

Membranolytic Activity of Bile Salts: Influence of Biological Membrane Properties and Composition

et al. 2007

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“…The nitroxide group of 12-DS is known to locate very close to the rigid steroidal framework and to be easily subject to the influence of molecules with steroidal structures. 12,13) Therefore, analysis of the ESR spectra of 12-DS should provide useful information about the behavior of Na-chol in vesicular membranes.…”

Section: Discussionmentioning

confidence: 99%

“…The present report deals with the influence of addition of small amounts (insufficient to destroy vesicles) of Na-chol on several physicochemical properties of PC small unilamellar vesicles (SUV). Similar to the previous reports, [12][13][14] ESR spectra of a spin label 12-doxylstearic acid (12-DS) are applied to monitor the variation in properties and structures of the mixed PC SUV. Differential scanning calorimetry (DSC) and z potentials measured with electrophoretic light scattering methods were also employed for observing the variation in the properties of PC SUV induced by Na-chol.…”

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confidence: 83%

Physical Properties of Phosphatidylcholine Vesicles Containing Small Amount of Sodium Cholate and Consideration on the Initial Stage of Vesicle Solubilization.

Sun

Kashiwagi

Ueno

2002

CHEMICAL & PHARMACEUTICAL BULLETIN

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Sodium cholate (Na-chol) is a physiological detergent. Its solubilizing properties are important in several fundamental biophysical and biochemical processes. This includes disintegration of biomembranes to mixed micelles, 1) reconstitution of membrane proteins and lipids to functional supramolecular structures (vesicles in most cases) 2,3) and preparation of homogeneous lipid vesicles of controlled sizes. 4,5) The vesicle destruction mechanism has been studied in connection with the reconstitution of membrane proteins after purification in detergent solutions. Concerning the disintegration from mixed vesicles to mixed micelles by Nachol, many studies have concentrated on the variation in morphology and properties of mixed aggregates.6,7) Consequently, the solubilization process of phosphatidylcholine (PC) vesicles is summarized as follows; addition of very small amounts of Na-chol to vesicles results in the partitioning of Na-chol between the water and lipid phases. At a further increased detergent concentration, vesicles containing a large amount of Na-chol are formed, whose behavior, such as fusion of small vesicles to larger ones, is found to be different from that of PC vesicles containing large amounts of nonionic detergents (i.e. octylglucoside).5) At a still further increased detergent concentration, the Na-chol-containing vesicles disintegrate into intermediate structures, and finally into mixed micelles. 8,9) As far as intermediate structures are concerned, structural changes from vesicles to perforated vesicles, to discoidal sheets, 10) or to rod-like structures 11) have been reported. As described above, the incorporation of Na-chol into vesicular membranes remarkably influences the structures and properties of PC vesicles. However, little is known about the effects of the incorporation of Na-chol on the behavior of membranes at a molecular level, although it is important for further detailed studies on the mechanism of vesicle disintegration. The present report deals with the influence of addition of small amounts (insufficient to destroy vesicles) of Na-chol on several physicochemical properties of PC small unilamellar vesicles (SUV). Similar to the previous reports, 12-14) ESR spectra of a spin label 12-doxylstearic acid (12-DS) are applied to monitor the variation in properties and structures of the mixed PC SUV. Differential scanning calorimetry (DSC) and z potentials measured with electrophoretic light scattering methods were also employed for observing the variation in the properties of PC SUV induced by Na-chol. The obtained results will be considered in connection with the initial stage of the solubilization of PC vesicular membranes. ExperimentalMaterials Phosphatidylcholine isolated from egg yolk (EPC) (purity approximately 98.8%) was purchased from Nihon Yushi (Tokyo, Japan). Sodium cholate and cholesterol of guaranteed degree were obtained from Nacalai Tesque (Kyoto, Japan). Synthetic dimyristoylphosphatidylcholine (DMPC) (purity ca. 99%) as well as 5-, 12-, and 16-DS were purchased from...

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“…were studied by many researchers. [4][5][6][7][8][9][10][11][12][13][14][15][16] The results obtained from e.m.f. measurements, carried out as a function of hydrogen ions, reagents and ionic medium 17 concentrations on aqueous sodium salt solution of dihydroxycholanic acids (deoxycholate = NaDC 18 , glycodeoxycholate = NaGDC 19 and taurodeoxycholate = NaTDC 20 ), were explained by assuming the presence of several species with different odd high aggregation numbers and also formed with the uptake of protons.…”

Section: Introductionmentioning

confidence: 99%

Composition of Sodium Cholate Micellar Solutions

Bottari¹,

Buonfigli²,

Festa³

2005

Annali di Chimica

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To study the composition of sodium cholate solutions, an investigation was carried out at 25 degrees C and in N(CH3)4Cl, as a constant ionic medium, at three different concentrations (W = 0.100; 0.500 and 0.800 mol dm(-3)). Electromotive force measurements of three different galvanic cells, the first involving a glass electrode for hydrogen ions, the second an electrode for sodium ions and the third a lead amalgam electrode, were performed. Independently, lead (II) cholate solubility measurements in the presence of sodium ions were performed, as well. The experimental results obtained from both approaches were explained by assuming the formation of aggregates in cholate and sodium of different composition depending on W and on the cholate concentration. The maximum aggregation found number for cholate was 24 and even aggregation numbers were markedly predominant. Only two species with odd aggregation number were found, but at a low percentage. The assumed species and the relative constants were compared with those found for the other sodium salt of cholanic acids.

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Spin-label studies of bile salt micelles

Cited by 163 publications

References 3 publications

Membranolytic Activity of Bile Salts: Influence of Biological Membrane Properties and Composition

Membranolytic Activity of Bile Salts: Influence of Biological Membrane Properties and Composition

Physical Properties of Phosphatidylcholine Vesicles Containing Small Amount of Sodium Cholate and Consideration on the Initial Stage of Vesicle Solubilization.

Composition of Sodium Cholate Micellar Solutions

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