Journal ArticleDOI
Quasielastic light-scattering studies of aqueous biliary lipid systems. Mixed micelle formation in bile salt-lecithin solutions.
TLDR
The inclusion of bile salts in a fixed stoichiometry within the interior of the bilayers is shown to provide a quantitative explanation for the divergence of the mixed micellar sizes, their temperature dependence, and the origin of the lecithin-bile salt phase limit.Abstract:
From measurements of the autocorrelation function and time-averaged intensity of light scattered from aqueous bile salt-lecithin solutions, we deduced the mean hydrodynamic radius (Rh), shape, and polydispersity of bile salt-lecithin mixed micelles as functions of bile salt species, lecithin to bile salt (L/BS) molar ratio, total lipid concentration (0.625-10 g/dL), temperature (20-60 degrees C), and NaCl concentration (0.15-0.6 M). Our data suggest that at low L/BS ratios (0 to approximately 0.6) simple bile salt micelles coexist in varying proportions with minimum-sized mixed micelles (Rh, 18-35 A). These solutions are highly polydisperse and display features dependent upon the particular bile salt species. At high L/BS ratios (greater than 0.6), only mixed micelles are present, and their sizes increase markedly (Rh, 20 leads to 300 A) with increases in L/BS ratio and appear to diverge as the lecithin-bile salt phase limit is approached. The shape of the mixed micelles as deduced from light-scattering measurements and confirmed by transmission electron microscopy is disklike. The radii of the disks, however, are not compatible with Small's model of mixed micellar structure [Small, D.M. (1967a) Gastroenterology 52, 607-a1 but are consistent with a new model proposed here in which bile salts and lecithin interact to form a mixed bilayer disk which is surrounded on its perimeter by bile salts. The inclusion of bile salts in a fixed stoichiometry within the interior of the bilayers is shown to provide a quantitative explanation for the divergence of the mixed micellar sizes, their temperature dependence, and the origin of the lecithin-bile salt phase limit. The influence of total lipid concentration on both mixed micellar size and the lecithin-bile salt phase limit is explained by the "mixed disk" model by taking account of the equilibrium between mixed micelles and bile salt monomers in the intermicellar solution. By use of this concept, deductions of the intermicellar bile salt concentration in taurocholate-lecithin solutions are made and are shown to vary as a function of mixed micellar size and temperature. The range of values obtained, 3-6 mM, is comparable in magnitude to the critical micellar concentration of the pure bile salt.read more
Citations
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Journal ArticleDOI
Membrane proteins, lipids and detergents: not just a soap opera
TL;DR: This review will concentrate on the methods currently available for efficient reconstitution and solubilization of membrane proteins through the use of detergent micelles, mixed lipid/detergent micella and bicelles or liposomes and the role that lipids can play in stabilizing the proteins.
Journal ArticleDOI
Interaction of membrane proteins and lipids with solubilizing detergents.
TL;DR: The nature of detergent binding by the membrane from a noncooperative to a cooperative interaction already below the critical micellar concentration is considered and it is concluded that in general binding as a monolayer ring, rather than as a micelle, is the most probable mechanism.
Journal ArticleDOI
Solubilization of phospholipids by detergents. Structural and kinetic aspects.
TL;DR: The information available to date on the solubilization of phospholipids, which constitute the lipid skeleton of biomembranes, by the common detergents is discussed in this review, both with respect to the kinetics of this process and the structure of the variousospholipid-detergent mixed micelles formed.
Journal ArticleDOI
Reconstitution of membrane proteins into liposomes: application to energy-transducing membrane proteins.
Journal ArticleDOI
The mechanism of vesicle formation.
TL;DR: Vesicles are very important in many different areas of science and technology and serve as delivery vehicles for drugs, genetic material, enzymes and other (macro)molecules into living cells and through other hydrophobic barriers in pharmacology, medicine, genetic engineering, cosmetic industry and food industry.
References
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Journal ArticleDOI
Analysis of Macromolecular Polydispersity in Intensity Correlation Spectroscopy: The Method of Cumulants
TL;DR: The first order electric field correlation function of laser light scattered by polydisperse solutions of macromolecules can be written as a sum or distribution of exponentials, with decay rates proportional to the diffusion coefficients of the solute molecules as discussed by the authors.
Journal ArticleDOI
Molecular motion in spin-labeled phospholipids and membranes
Journal ArticleDOI
Mouvement Brownien d'un ellipsoide (II). Rotation libre et dépolarisation des fluorescences. Translation et diffusion de molécules ellipsoidales
TL;DR: In this article, the diffusion of molecules ellipsoidales dissoutes is analyzed in a mouvement brownien d'ensemble (rotation and translation) with respect to a set of molecules.
Journal ArticleDOI
Studies on lecithin-cholesterol-water interactions by differential scanning calorimetry and X-ray diffraction
TL;DR: The cholesterol controls the fluidity of the hydrocarbon chains of the phospholipid by disruption of the crystalline chain lattice of the gel phase, and by inhibiting the flexing of chains in the dispersed liquid crystalline phase.
Journal ArticleDOI
The physical chemistry of cholesterol solubility in bile. Relationship to gallstone formation and dissolution in man.
Martin C. Carey,Donald Small +1 more
TL;DR: The results demonstrate that cholesterol gallstone patients have supersaturated gallbladder and hepatic biles without exception, and the predominant driving force for cholesterol precipitation appears to be the absolute degree of cholesterol supersaturation.
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