Showing papers on "Membrane published in 1975"
TL;DR: This review focuses on work that deals with the mechanisms of detergent action in membrane solubilization including properties of detergents model lipid systems and detergent-protein interactions; in addition a possible sequence of events when deterGents interact with biological membranes receives attention.
2,850 citations
TL;DR: A 7-Å resolution map of the purple membrane has been obtained by electron microscopy of tilted, unstained specimens and shows that Lipid bilayer regions fill the spaces between the protein molecules.
Abstract: A 7-A resolution map of the purple membrane has been obtained by electron microscopy of tilted, unstained specimens. The protein in the membrane contains seven, closely packed, alpha-helical segments which extend roughly perpendicular to the plane of the membrane for most of its width. Lipid bilayer regions fill the spaces between the protein molecules.
2,114 citations
TL;DR: It is suggested that for a realistic situation translational diffusion should be about four times faster in relation to rotational diffusion than in the isotropic case.
Abstract: Brownian motion (diffusion) of particles in membranes occurs in a highly anisotropic environment. For such particles a translational mobility (independent of velocity) can be defined if the viscosity of the liquid embedding the membrane is taken into account. The results of a model calculation are presented. They suggest that for a realistic situation translational diffusion should be about four times faster in relation to rotational diffusion than in the isotropic case.
1,611 citations
TL;DR: The cell envelope of Enterobacteriaceae consists of two membranes separated by a peptidoglycan layer, and methods have been developed to separate the cytoplasmic membrane from the outer membrane.
1,456 citations
TL;DR: The proton pumping of the purple membrane suggests that bacteriorhodopsin undergoes a light-induced cyclic reaction involving a proton release on one side of the membrane and proton uptake on the opposite side, suggesting a chemiosmotic mechanism for energy transduction.
882 citations
Book•
21 Aug 1975
TL;DR: In this article, the theory of membrane potentials in ion-selective electrodes is discussed and principal properties of these electrodes are investigated, and Voltammetry at the interface of two immiscible electrolyte is presented.
Abstract: Preface 1. Introduction 2. The theory of membrane potentials 3. The theory of membrane potentials in ion-selective electrodes 4. Principal properties of ion-selective electrodes 5. Experimental techniques 6. Ion-selective electrodes with solid or glassy membranes 7. Ion-selective electrodes with liquid membranes 8. Potentiometric biosensors 9. Voltammetry at the interface of two immiscible electrolyte Appendix Index.
802 citations
TL;DR: For example, cells of many kinds adhere firmly to glass or plastic surfaces which have been pretreated with polylysine as discussed by the authors and the attachment takes place as soon as the cells make contact with the surfaces, and the flattening of the cells against the surfaces is quite rapid.
Abstract: Cells of many kinds adhere firmly to glass or plastic surfaces which have been pretreated with polylysine. The attachment takes place as soon as the cells make contact with the surfaces, and the flattening of the cells against the surfaces is quite rapid. Cells which do not normally adhere to solid surfaces, such as sea urchin eggs, attach as well as cells which normally do so, such as amebas or mammalian cells in culture. The adhesion is interpreted simply as the interaction between the polyanionic cell surfaces and the polycationic layer of adsorbed polylysine. The attachment of cells to the polylysine-treated surfaces can be exploited for a variety of experimental manipulations. In the preparation of samples for scanning or transmission electron microscopy, the living material may first be attached to a polylysine-coated plate or grid, subjected to some experimental treatment (fertilization of an egg, for example), then transferred rapidly to fixative and further passed through processing for observation; each step involves only the transfer of the plate or grid from one container to the next. The cells are not detached. The adhesion of the cell may be so firm that the body of the cell may be sheared away, leaving attached a patch of cell surface, face up, for observation of its inner aspect. For example, one may observe secretory vesicles on the inner face of the surface (3) or may study the association of filaments with the inner surface (Fig. 1). Subcellular structures may attach to the polylysine-coated surfaces. So far, we have found this to be the case for nuclei isolated from sea urchin embryos and for the microtubules of flagella, which are well displayed after the membrane has been disrupted by Triton X-100 (Fig. 2).
762 citations
TL;DR: Aromatic polyamide asymmetric "skin type" membranes have been prepared by the Loeb-Sourirajan technique as mentioned in this paper, and two different structures were obtained, depending on the rate of precipitation.
537 citations
TL;DR: The name cochleate lipid cylinders is suggested for the spiral structures formed by fusion of unilamellar vesicles into large sheets which fold spirally to form cylinders in phosphatidylserine preparations.
527 citations
TL;DR: The asymmetric density of RCAI receptors across the zona was confirmed by ferritin- RCAI and fluorescein-RCAI labeling of mechanically isolated zonae pellucidae, indicating that the RCAi-binding sites are more densely distributed in the exterior zona regions.
Abstract: Receptors for Ricinus communis agglutinin I (RCAI), concanavalin A (Con A), and wheat germ agglutinin (WGA) were localized on the zonae pellucidae and plasma membranes of hamster, mouse, and rat eggs with ferritin-lectin conjugates Intact eggs labeled with the ferritin conjugates showed dense concentrations of RCAI and WGA receptors in the outermost regions of their zonae pellucidae and sparse distributions of Con A receptors throughout the zonae Ferritin-lectin labeling was specific, since inhibitory saccharides effectively blocked labeling The asymmetric density of RCAI receptors across the zona was confirmed by ferritin-RCAI and fluorescein-RCAI labeling of mechanically isolated zonae pellucidae, indicating that the RCAI-binding sites are more densely distributed in the exterior zona regions Plasma membranes of rodent eggs contained RCAI, WGA, and Con A receptors These receptors were found to be more or less randomly distributed on surfaces of aldehyde-fixed eggs or on eggs labeled near 0 degrees C However, eggs incubated at 25 degrees C showed aggregated WGA- and Con A-binding site distributions on their plasma membranes This indicates that lectin-induced receptor redistribution occurs at this temperature The possibility that plasma membrane receptor mobility is a requirement for sperm-egg fusion is discussed
473 citations
TL;DR: Research interest in the milk fat globule membrane has been strong because of its importance in properties of milk and milk products and the relevance of mammary cell membranes to the breast cancer problem.
TL;DR: The model of the lipids and proteins of membranes called the “fluid mosaic model” is adopted as a working hypothesis of membrane structure and what it might imply about the mechanisms of a variety of important cellular functions and activities is considered.
Abstract: An area of intense current interest in molecular and cell biology is the structure of biological membranes. A great change in our picture of membranes has occurred in the last few years, and there is now fairly widespread acceptance of a model for the organization of the lipids and proteins of membranes called the “fluid mosaic model” (Singer and Nicolson, 1972). In this model (Fig. 1) the proteins that are integral to the membrane (Singer, 1971) are proposed to be globular molecules which are partly embedded in the membrane lipid, and partly protrude from it. This partial embedding is determined thermodynamically by the amphipathic character of the integral protein molecule; its hydrophobic end is embedded in the hydrophobic membrane interior and its hydrophilic end protrudes into the aqueous phase. The lipid, arranged largely as a bilayer, forms the matrix of the membrane, and since at physiological temperatures the lipid of most functional membranes is largely fluid, the integral proteins are in principle free to move about laterally and rapidly in the plane of the membrane. There is now a very substantial body of evidence that is consistent with, and strongly supports, the fluid mosaic model. The discussion of this evidence could easily occupy my entire presentation, but I thought that in the context of this symposium it might be more useful to adopt the model as a working hypothesis of membrane structure and consider what it might imply about the mechanisms of a variety of important cellular functions and activities.
TL;DR: Current concepts about the molecular composition, organisation and behaviour of the plasma membranes of mammalian erythrocytes and nucleated cells are discussed.
Abstract: 1975 is the fiftieth anniversary of the proposal, by Gorter and Grendel, that biological membranes are based on a lipid bilayer. Now well established, this proposal, like the DNA double helix, was a major breakthrough in molecular cell biology. Here we discuss current concepts about the molecular composition, organisation and behaviour of the plasma membranes of mammalian erythrocytes and nucleated cells.
TL;DR: The outer membrane layer of the cell wall was isolated from wild-type Salmonella typhimurium LT2 as well as from its mutants producing lipopolysaccharides with shorter saccharide chains, suggesting the largely proteinaceous nature of particles.
Abstract: The outer membrane layer of the cell wall was isolated from wild-type Salmonella typhimurium LT2 as well as from its mutants producing lipopolysaccharides with shorter saccharide chains. Chemical analysis of these preparations indicated the following. (i) The number of lipopolysaccharide molecules per unit area was constant, regardless of the length of the saccharide side chain in lipopolysaccharide. (ii) In contrast, in "deep rough" (Rd or Re) mutants producing the lipopolysaccharides with very short saccharide chains, the amount of outer membrane protein per unit surface area decreased to about 60% of the value in the wild type. (iii) In the wild type, the amount of phospholipids is slightly less than what is needed to cover one side of the membrane as a monolayer. In comparison with the wild type, the outer membrane of Rd and Re mutants contains about 70% more phospholipids, which therefore must be distributed in both the outer and inner leaflets of the membrane. Freeze-fracture studies showed that the outer membrane of Re mutants were easily fractured, but fracture became increasingly difficult in strains producing lipopolysaccharides with longer side chains. The convex fracture face was always nearly smooth, but the concave fracture face or the outer half of the membrane was densely covered with particles 8 to 10 nm in diameter. The density of particles was decreased in Re mutants to the same extent as the reduction in proteins, suggesting the largely proteinaceous nature of particles. A model for the supramolecular structure of the outer membrane is presented on the basis of these and other results.
TL;DR: X-ray diffraction analysis of oriented specimens of the purple membrane from Halobacterium halobium shows that the protein and lipid components are packed in a P 3 hexagonal lattice, with one protein molecule per asymmetric unit.
TL;DR: The results support the hypothesis that once initiated, the propagation of cortical granule discharge spreads as an autocatalytic wave in which discharging granules release Ca2+ through their membranes which in turn triggers the discharge of adjacent granules.
TL;DR: The enzymatic iodination technique has been utilized in a study of the externally disposed membrane proteins of the mouse L cell with no loss of cell viability under the conditions employed, less than 3% lipid labeling, and more than 90% of the labeled species identifiable as monoiodotyrosine.
Abstract: The enzymatic iodination technique has been utilized in a study of the externally disposed membrane proteins of the mouse L cell. Iodination of cells in suspension results in lactoperoxidase-specific iodide incorporation with no loss of cell viability under the conditions employed, less than 3% lipid labeling, and more than 90% of the labeled species identifiable as monoiodotyrosine. 90% of the incorporated label is localized to the cell surface by electron microscope autoradiography, with 5-10% in the centrosphere region and postulated to represent pinocytic vesicles. Sodium dodecylsulfate-polyacrylamide gels of solubilized L-cell proteins reveals five to six labeled peaks ranging from 50,000 to 200,000 daltons. Increased resolution by use of gradient slab gels reveals 15-20 radioactive bands. Over 60% of the label resides in approximately nine polypeptides of 80,000 to 150,000 daltons. Various controls indicate that the labeling pattern reflects endogenous membrane proteins, not serum components. The incorporated 125-I, cholesterol, and one plasma membrane enzyme marker, alkaline phosphodiesterase I, are purified in parallel when plasma membranes are isolated from intact, iodinated L cells. The labeled components present in a plasma membrane-rich fraction from iodinated cells are identical to those of the total cell, with a 10- to 20-fold enrichment in specific activity of each radioactive peak in the membrane.
TL;DR: Cell membranes and intracellular materials are selectively solubilized with 4% sodium deoxycholate to yield morphologically and chemically intact basement membrane preparations and this method appears to be a versatile, nondisruptive procedure.
TL;DR: A good correlation was obtained between fluorescence polarization data on dibucaine-induced changes in membrane fluidity and calorimetric measurements on vesicles of the same type.
TL;DR: It is concluded that the regions of the large chain exposed in the presence of K+ are distinct from the regions exposed in presence of Na+ and that two conformations of (Na+, K+)-ATPase can be sensed with trypsin, a (T)K-form and a (t)Na-form.
TL;DR: In this article, phase diagrams representing lateral phase separations in the plane of lipid bilayer membranes have been determined for binary mixtures containing dielaidoylphosphatidylcholine together with dimyristoyl-phosphate-derived spin labels.
Abstract: Phase diagrams representing lateral phase separations in the plane of lipid bilayer membranes have been determined for binary mixtures containing dielaidoylphosphatidylcholine together with dimyristoylphosphatidylcholine, dipalmitoylphosphatidylcholine, distearoylphosphatidylcholine, dioleoylphosphatidylcholine, and dipalmitoylphosphatidylethanolamine. The phase diagrams were deduced from observations of the temperature dependence of the paramagnetic resonance spectra of low concentrations of spin-labels incorporated in these bilayer membranes. In one case, the binary mixture of dipalmitoylphosphatidylethamine and dielaidoylphosphatidylcholine, evidence has been obtained for fluid-fluid immiscibility, in specified temperature and compoistion ranges. This immiscibility could give a lateral phase separation into fluid domains in the plane of the membrane, and/or a transverse phase separation into an asymmetrical bilayer membrane, and/or possibly disco ntinuous bilayer membranes of different composition. An asymmetrical bilayer membrane can be expected on theoretical grounds to form a nonplanar membrane.
Patent•
15 Jul 1975TL;DR: A multilayer membrane, which is useful as synthetic skin, is described in this article, where a first layer is formed from a material which does not provoke an immune response and which is also insoluble and non-degradable in the presence of body fluids and/or body enzymes.
Abstract: A multilayer membrane, which is useful as synthetic skin, is disclosed herein. A first layer is formed from a material which does not provoke an immune response and which is also insoluble and nondegradable in the presence of body fluids and/or body enzymes. Preferred materials for the first layer are crosslinked composites of collagen and a mucopolysaccharide. A second layer is formed from a nontoxic material which controls the moisture flux of the overall membrane to about 0.1 to 1 mg./cm 2 /hr. Suitable materials for the second layer include synthetic polymers such as silicone resins, polyacrylate or polymethacrylate esters or their copolymers, and polyurethanes.
TL;DR: It is concluded that the increased permeability at the transition temperature cannot be ascribed to "macroscopic" rupture of the liposomal membrane, and the maximum permeability in the vicinity of the Tc is discussed in terms of probability and size distribution of statistical pore formation at the boundaries of liquid and solid domains.
Patent•
24 Sep 1975
TL;DR: A laminated membrane for use with an enzyme electrode without the need for use of a compensating electrode was proposed in this paper, which consists of essentially homogeneous material such as cellulose acetate or silicone rubber which will prevent passage of even low molecular weight interfering materials, an adhesive layer of the enzyme itself (with or without other materials that may be blended with it), and a layer of support film which will also prevent the passage of high molecular weight interference materials.
Abstract: A laminated membrane for use with an enzyme electrode without the need for use of a compensating electrode. The laminated membrane comprises a layer of essentially homogeneous material such as cellulose acetate or silicone rubber which will prevent passage of even low molecular weight interfering materials, an adhesive layer of the enzyme itself (with or without other materials that may be blended with it), and a layer of support film which will also prevent the passage of high molecular weight interfering materials.
TL;DR: It is suggested that Helfrich's concept of edge energy of a lipid bilayer explains the stability of black membranes and the ability of erythrocytes to reseal following hemolysis.
Patent•
19 Jun 1975
TL;DR: In this paper, an improved method for topically administering a physiologically active agent to a human or animal by dissolving an effective amount of the agent in a carrier containing suitable amounts of 1-substituted-azacycloheptan-2-one, as defined herein, was disclosed.
Abstract: There is disclosed an improved method for topically administering a physiologically active agent to a human or animal by dissolving an effective amount of the agent in a carrier containing suitable amounts of 1-substituted-azacycloheptan-2-one, as defined herein, and contacting the skin or other membranes of the human or animal with the resulting composition, whereby penetration of the skin or membranes is enhanced.
TL;DR: This paper presents a general model for coupled solute and water flow through plant roots based on the thermodynamics of irreversible processes and shows that with a constant hydraulic conductivity the only features necessary to explain these phenomena are some type of membrane or membranelike structure and a mechanism for actively accumulating solutes.
Abstract: This paper presents a general model for coupled solute and water flow through plant roots based on the thermodynamics of irreversible processes. The model explains in a straight-forward manner such experimentally observed phenomena as changes in root resistance, increased solute flux, and apparent negative resistance, which have been reported for root systems under the influence of a hydrostatic pressure gradient. These apparent anomalies are explained on the basis of the interaction between the osmotic and hydrostatic driving forces and the well known "sweeping away" or dilution effect. We show that with a constant hydraulic conductivity the only features necessary to explain these phenomena are some type of membrane or membranelike structure and a mechanism for actively accumulating solutes.
TL;DR: The "condensing" effect of cholesterol in mixed phospholipid-cholesterol films is seen as a taper-fray accommodation and the lipid distribution in erythrocyte membrane is shown to be conducive to a stable strain-free membrane.