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Showing papers on "Membrane published in 1987"


Journal ArticleDOI
TL;DR: Small amounts of myoglobin, beta-lactoglobulin, and other proteins and peptides can be spotted or electroblotted onto polyvinylidene difluoride membranes, stained with Coomassie Blue, and sequenced directly, suggesting that PVDF membranes are superior supports for sequence analysis of picomole quantities of proteins purified by gel electrophoresis.

4,869 citations



Journal ArticleDOI
TL;DR: In this paper, the concept of temperature polarisation is introduced and shown to be important in the interpretation of experimental results, and hollow fiber and tubular membrane distillation systems are discussed.

618 citations


01 Jan 1987
TL;DR: Osmotic Equilibrium Osmotic Transport (Osmosis) Induced by an Impermeant Solute Tracer Diffusion of Water Single-file Transport Osmotics Permeability Index.
Abstract: THEORY: Osmotic Equilibrium Osmotic Transport (Osmosis) Induced by an Impermeant Solute Tracer Diffusion of Water Single-file Transport Osmotic Transport (Osmosis) LIPID BILAYER MEMBRANES: The Unmodified Membrane Nystatin an Amphotericin B. Gramicidin A PLASMA MEMBRANES: General Considerations The Red Cell Membrane Epithelia: Antidiuretic Hormone (ADH)-Induced Water Permeability Index.

530 citations


Journal ArticleDOI
TL;DR: In this article, the interplay between crystalline (or hexatic) order and thermal fluctuations in membranes with vanishing surface tension is studied, and a finite temperature crumpling transition is predicted for crystalline membranes.
Abstract: We study the interplay between crystalline (or hexatic) order and thermal fluctuations in membranes with vanishing surface tension. If the connectivity of the crystalline state is preserved, the membrane remains uncrumpled at low temperatures. When dislocations are allowed, however, screening of elastic stresses by buckling reduces dislocation energies, and promotes dislocation unbinding. When the resulting hexatic phase is stable, the stiffness associated with orientational correlations leads to a logarithmic enhancement of the bending rigidity which counteracts the thermal softening found in fluid surfaces. A finite temperature crumpling transition is predicted for crystalline membranes, and possibly for hexatic membranes as well.

529 citations


Journal ArticleDOI
TL;DR: It is proposed that prior interaction between the toxin and cell-specific plasma membrane recpetors is necessary before these toxins can insert into, or interact with, the membrane.

463 citations


Journal ArticleDOI
TL;DR: A new role is proposed for phospholipase A 2 in protecting membranes from oxidative injury by reducing and detoxifying fatty acid hydroperoxides in membranes.

427 citations


Book ChapterDOI
TL;DR: This chapter describes a method using the preparation of plasma membranes from light-grown oat leaves as an example, and estimates the purity to be higher than 90% and often close to 100%, plasma membrane and similar purities are reported for plasma membrane from maize roots.
Abstract: Publisher Summary This chapter describes a method using the preparation of plasma membranes from light-grown oat ( Arena sativa L. ) leaves as an example. Using the batch procedure, two fractions containing purified plasma membrane (U 3 and U 3 , ) and one fraction containing intracellular membranes depleted of plasma membrane (L 1 ) are obtained. Specific staining with phosphotungstic acid or silicotungstic acid seems to be the only universal marker for the plant plasma membrane and the only one that permits a real estimation of the purity of the preparations. Based on this staining the purity is estimated to be higher than 90% and often close to 100%, plasma membrane and similar purities are reported for plasma membrane from maize roots. (>90%) for plasma membrane preparations obtained both by phase partitioning and free flow electrophoresis.

406 citations


Journal ArticleDOI
TL;DR: In this paper, the selectivity of a silicone membrane for a gas A relative to a gas B, i.e., the permeability ratio P(A)/P(B), may increase or decrease as a result of substitutions, but only if the substituted groups are sufficiently bulky.
Abstract: Permeability coefficients P for He, O2, N2, CO2 CH4, C2H4, C2H6, and C3H8 in 12 different silicone polymer membranes were determined at 35.0°C and pressures up to 9 atm. Values of P for CO2, CH4, and C3H8 were also determined at 10.0 and 55.0°C. In addition, mean diffusion coefficients D and solubility coefficients S were obtained for CO2, CH4, and C3H8 in 6 silicone polymers at 10.0, 35.0, and 55.0°C. Substitution of increasingly bulkier functional groups in the side and backbone chains of silicone polymers results in a significant decrease in P for a given penetrant gas. This is due mainly to a decrease in D, whereas S decreases to a much lesser extent. Backbone substitutions appear to have a somewhat lesser effect in depressing P than equivalent side-chain substitutions. The selectivity of a silicone membrane for a gas A relative to a gas B, i.e., the permeability ratio P(A)/P(B), may increase or decrease as a result of such substitutions, but only if the substituted groups are sufficiently bulky. The selectivity of the more highly permeable silicone membranes is controlled by the ratio S(A)/S(B), whereas the selectivity of the less permeable membranes depends on both the ratios D(A)/D(B) and S(A)/S(B). The permeability as well as the selectivity of one silicone membrane toward CO2 were significantly enhanced by the substitution of a fluorine-containing side group that increased the solubility of CO2 in that polymer.

389 citations


Journal ArticleDOI
TL;DR: In this article, the ternary diffusion process that occurs in a cellulose acetate (CA) -acetone casting solution immersed into a water bath has been investigated and the necessary concentration dependent thermodynamic and hydrodynamic parameters have been derived from experimental data on the three limiting binary mixtures.

377 citations


Journal ArticleDOI
TL;DR: In this article, the maximum allowable concentration for a (micro)porous membrane under process conditions can be determined, by means of theoretical considerations, for a homogeneous smooth material (gq < 90/deg) can be calculated.


Journal ArticleDOI
TL;DR: In this article, a critical review on the mass transfer correlations under turbulent duct flow, as they appeared in the literature ( 1934-1984), and a discussion on the factors influencing mass transfer during membrane operations (reverse osmosis and ultrafiltration), like porosity and roughness of the membrane wall and change of viscosity and diffusion coefficient due to the strong concentration gradient.

Book
12 Mar 1987
TL;DR: In this article, Osmotic equilibria were induced by an Impermeant Solute Tracer Diffusion of Water Single-file Transport (Osmosis) and Gramicidin.
Abstract: THEORY: Osmotic Equilibrium Osmotic Transport (Osmosis) Induced by an Impermeant Solute Tracer Diffusion of Water Single-file Transport Osmotic Transport (Osmosis) LIPID BILAYER MEMBRANES: The Unmodified Membrane Nystatin an Amphotericin B. Gramicidin A PLASMA MEMBRANES: General Considerations The Red Cell Membrane Epithelia: Antidiuretic Hormone (ADH)-Induced Water Permeability Index.

Journal ArticleDOI
TL;DR: The methods of classical, three-dimensional continuum mechanics must be compressed into a two-dimensional world in which "stress resultants" or "tensions" (force per unit width of membrane surface) are defined on the surface of the membrane.
Abstract: The classical theory of elasticity (35) treats the material of a deformable body as a three-dimensional continuum in which internal stresses occur as the body is deformed by external forces acting over its surface. Although the internal stresses are caused by the displacement of atoms or molecules from an original state of equilibrium, the molecular character of the material is ignored. This means that every volume element within the material must contain enough molecules to guarantee that the thermal fluctuation of anyone molecule does not effect the local state of stress. Since biomembranes in general and red cell membranes in particular are only a few molecules thick, they can form a continuum only in the plane of the membrane. Thus, the methods of classical, three-dimensional continuum mechanics must be compressed into a two-dimensional world in which "stress resultants" or "tensions" (force per unit width of membrane surface) are defined on the surface of the membrane (8, 25, 48). Measurement of the surface stress resultants and the corresponding surface deformations permits the material properties of the membrane surface to be calculated (15, 16, 20). These surface properties represent a summation, over the thickness of the membrane, of the properties of the lamellar, molecular structures that form the membrane.

Journal ArticleDOI
TL;DR: In this article, a novel type of hydrophobic zeolite has been used for the purpose of adding a sorptive filler with a high selectivity towards alcohol to improve both selectivity and flux.

Journal ArticleDOI
TL;DR: The evidence clearly indicates that membrane photomodification cannot be understood based only on the properties of sensitizers and singlet oxygen in aqueous solution and in membranes.
Abstract: This review discusses photomodification of biological membranes and model membrane systems. Current concepts of membrane structure are first reviewed briefly. The role of preillumination association of sensitizer with membranes as it relates to photomodification rate is discussed, as well as the role of singlet oxygen in membrane photomodification. Finally the characteristics of singlet oxygen generation in membranes are considered. The evidence clearly indicates that membrane photomodification cannot be understood based only on the properties of sensitizers and singlet oxygen in aqueous solution. Rather the properties of sensitizers in association with membranes are the determinants of membrane photomodifcation. These properties differ significantly in aqueous solution and in membranes.

Journal ArticleDOI
TL;DR: Whether lateral diffusion of membrane proteins over distances of a few micrometers is usually isotropic or anisotropic will be ascertained in the near future using imaging methods combined with photobleaching.
Abstract: Membrane protein lateral diffusion can be constrained in several ways: Diffusion can be slower than that predicted for a simple, fluid lipid bilayer; diffusion can be confined to certain regions within the total membrane; and diffusion may not be equally probable in all directions, i.e. it may be anisotropic. We know that protein diffusion is reduced by increasing concentrations of membrane proteins and by interactions of the diffusant with structure(s) peripheral to the membrane. The molecular nature of such peripheral constraints has been difficult to pinpoint, but attention is now being directed to the extracellular matrix in addition to the membrane-associated cytoskeleton. There are many proteins that are confined to lateral domains in differentiated, isolated cells and in cells organized into tissue. The mechanisms that maintain such inhomogeneous distributions should be elucidated in the next few years. Whether lateral diffusion of membrane proteins over distances of a few micrometers is usually isotropic or anisotropic will be ascertained in the near future using imaging methods combined with photobleaching.

Book
01 Jan 1987
TL;DR: The lipids of cell membranes membrane models and model membranes lipid properties in membranes cholesterol and cell membrane membrane proteins lipid-protein interactions and the roles of lipids in biological membranes transport membrane fusion membrane receptors the metabolism of membrane lipids membrane biogenesis.
Abstract: The lipids of cell membranes membrane models and model membranes lipid properties in membranes cholesterol and cell membranes membrane proteins lipid-protein interactions and the roles of lipids in biological membranes transport membrane fusion membrane receptors the metabolism of membrane lipids membrane biogenesis.

Patent
Richard Allen Hayes1
16 Apr 1987
TL;DR: Semi-flexible aromatic polyimides, prepared by polycondensation of dianhydrides with phenylene diamines having alkyl substituents on all ortho positions to the amine functions incorporating at least in part 3,3,4,4'-benzophenone tetracarboxylic diyanhydride, are auto photochemically crosslinkable as discussed by the authors.
Abstract: Semi-flexible aromatic polyimides, prepared by polycondensation of dianhydrides with phenylene diamines having alkyl substituents on all ortho positions to the amine functions incorporating at least in part 3,3',4,4'-benzophenone tetracarboxylic dianhydride, are auto photochemically crosslinkable. Membranes formed from this class of crosslinked polyimides have improved environmental stability and superior gas selectivity than the corresponding uncrosslinked polyimide. The range of gas permeation properties observed allows for the tailoring of membrane material for widely diverse gas separations. The high permeabilities of some gases from multicomponent mixtures is due to the optimization of the molecular free volume in the polymer.

Journal ArticleDOI
TL;DR: The structure of the coat was examined in proton-secreting, mitochondria-rich cells from toad urinary bladder epithelium by rapidly freezing portions of apical membrane and associated cytoplasm that were sheared away from the remainder of the cell using polylysine-coated coverslips to determine whether the coat contains a major membrane protein transported by these vesicles, a proton pumping H+ATPase.
Abstract: Specialized proton-secreting cells known collectively as mitochondria-rich cells are found in a variety of transporting epithelia, including the kidney collecting duct (intercalated cells) and toad and turtle urinary bladders. These cells contain a population of characteristic tubulovesicles that are believed to be involved in the shuttling of proton pumps (H+ATPase) to and from the plasma membrane. These transporting vesicles have a dense, studlike material coating the cytoplasmic face of their limiting membranes and similar studs are also found beneath parts of the plasma membrane. We have recently shown that this membrane coat does not contain clathrin. The present study was performed to determine the structure of this coat in rapidly frozen and freeze-dried tissue, and to determine whether the coat contains a major membrane protein transported by these vesicles, a proton pumping H+ATPase. The structure of the coat was examined in proton-secreting, mitochondria-rich cells from toad urinary bladder epithelium by rapidly freezing portions of apical membrane and associated cytoplasm that were sheared away from the remainder of the cell using polylysine-coated coverslips. Regions of the underside of these apical membranes as large as 0.2 micron2 were decorated by studlike projections that were arranged into regular hexagonal arrays. Individual studs had a diameter of 9.5 nm and appeared to be composed of multiple subunits arranged around a central depression, possibly representing a channel. The studs had a density of approximately 16,800 per micron2 of membrane. Similar arrays of studs were also found on vesicles trapped in the residual band of cytoplasm that remained attached to the underside of the plasma membrane, but none were seen in adjacent granular cells. To determine whether these arrays of studs contained H+ATPase molecules, we examined a preparation of affinity-purified bovine medullary H+ATPase, using the same technique, after incorporation of the protein eluted from a monoclonal antibody affinity column into phospholipid liposomes. The affinity-purified protein was shown to be capable of ATP-dependent acidification. In such preparations, large paracrystalline arrays of studs identical in appearance to those seen in situ were found. The dimensions of the studs as well as the number per square micrometer of membrane were identical to those of toad bladder mitochondria-rich cells: 9.5 nm in diameter, 16,770 per micron2 of membrane.(ABSTRACT TRUNCATED AT 400 WORDS)

Journal ArticleDOI
TL;DR: The phenomenological similarity of the cell and lipid membrane breakdown indicates that pores developed during the electrical breakdown of biological membranes arise in their lipid matrices.

Journal ArticleDOI
TL;DR: The transmembrane movement of the fluorescent phosphatidylserine and phosph atidylethanolamine analogs was inhibited when the unnatural D-isomers of these lipids were used, further suggesting that this process was stereospecific and therefore likely to have been protein-mediated.

Journal ArticleDOI
TL;DR: The biophysical consequences of lipid peroxidation in biological membranes are reviewed, and studies with microsomal cytochrome P-450 suggest protein aggregation but not the increased lipid order to be the major cause of protein immobilized membranes.

Journal ArticleDOI
TL;DR: The data strongly indicate that fibroblast surface membranes consist of protein-rich domains approximately 1 micron in diameter, embedded in a relatively protein-poor lipid continuum.
Abstract: We have used the technique of fluorescence photobleaching recovery to measure the lateral diffusion coefficients and the mobile fractions of a fluorescent lipid probe, 1-acyl-2-(12-[(7-nitro-2-1, 3-benzoxadiazol-4-yl)aminododecanoyl]) phosphatidylcholine (NBD-PC), and of labeled membrane proteins of human fibroblasts. Values for mobile fractions decrease monotonically with increasing size of the laser spot used for the measurements, over a range of 0.35-5.0 microns. Values for NBD-PC diffusion coefficients increase in part of this range to reach a plateau at larger laser spots. This variation is not an artifact of the measuring system, since the effects are not seen if diffusion of the probe is measured in liposomes. We also find that the distribution of diffusion coefficients measured with small laser spots is heterogeneous indicating that these small spots can sample different regions of the membrane. These regions appear to differ in protein concentration. Our data strongly indicate that fibroblast surface membranes consist of protein-rich domains approximately 1 micron in diameter, embedded in a relatively protein-poor lipid continuum. These features appear in photographs of labeled cell surfaces illuminated by the expanded laser beam.

Journal ArticleDOI
TL;DR: The energetics of membrane-protein interactions are analyzed with the three-dimensional model of the photosynthetic reaction center from Rhodobacter sphaeroides, showing an asymmetry in the potential between the two possible pathways of electron transfer, with the A branch being preferred electrostatically.
Abstract: The energetics of membrane-protein interactions are analyzed with the three-dimensional model of the photosynthetic reaction center (RC) from Rhodobacter sphaeroides. The position of the RC in the membrane and the thickness of the membrane were obtained by minimizing the hydrophobic energy with the energy function of Eisenberg and McLachlan. The 2-fold symmetry axis that relates the L and M subunits is, within the accuracy of 5 degrees, parallel to the normal of the membrane. The thickness of the membrane is estimated to be 40-45 A. Residues that are exposed to the membrane are relatively poorly conserved in the sequences of homologous RC proteins. The surface area of the RC is comparable to the surface areas of water-soluble proteins of similar molecular weight. The volumes of interior atoms in the RC are also similar to those of water-soluble proteins, indicating the same compact packing for both types of proteins. The electrostatic potential of the cofactors was calculated. The results show an asymmetry in the potential between the two possible pathways of electron transfer, with the A branch being preferred electrostatically.

Journal ArticleDOI
27 Nov 1987-Science
TL;DR: The last 37 amino acids of membrane DAF, when fused to the carboxyl terminus of a secreted protein, are sufficient to target the fusion protein to the plasma membrane by means of a glycophospholipid anchor.
Abstract: Decay accelerating factor (DAF) belongs to a novel group of membrane proteins anchored to the cell surface by a glycophospholipid membrane anchor that is covalently attached to the carboxyl terminus of the protein. The last 37 amino acids of membrane DAF, when fused to the carboxyl terminus of a secreted protein, are sufficient to target the fusion protein to the plasma membrane by means of a glycophospholipid anchor. This approach provides a novel means of targeting proteins to the cell-surface membrane.

Journal ArticleDOI
TL;DR: Chloride transport determined with SPQ was validated by measurement of erythrocyte chloride/anion exchange and membrane vesicle chloride conductance.
Abstract: Transport of chloride across cell membranes through exchange, cotransport, or conductive pathways is a subject of great biological importance. Current methods of measurement are restricted in their sensitivity, time resolution, and applicability. A new transport measurement technique has been developed on the basis of the fluorescence quenching by chloride of the dye 6-methoxy-N-(3-sulfopropyl)quinolinium (SPQ). SPQ fluorescence quenching by chloride is rapid (less than 1 ms) and sensitive, with a greater than 50% decrease in fluorescence at 10 mM chloride. SPQ fluorescence is not altered by other physiological anions or by pH and can be used to measure both neutral and conductive transport processes. The high water solubility and membrane permeability properties of SPQ make it ideal for use in both membrane vesicles and cells. Chloride transport determined with SPQ was validated by measurement of erythrocyte chloride/anion exchange and membrane vesicle chloride conductance.

Journal ArticleDOI
TL;DR: The cyclicGMP-dependent cation channel from bovine rod outer segments has been purified to greater than 90% homogeneity by a rapid two-step chromatographic procedure and the drug l-cis-diltiazem, shown to block the cyclic GMP- dependent channel in excised patches of the plasma membrane and in isolated disks of rod outer segment, was ineffective against the purified channel.
Abstract: The cyclic GMP-dependent cation channel from bovine rod outer segments has been purified to greater than 90% homogeneity by a rapid two-step chromatographic procedure. The purified channel has an apparent molecular mass of 63 kDa as determined by NaDodSO4/gel electrophoresis. When incorporated into the membrane of liposomes, the purified protein mediates the cyclic GMP-dependent efflux of entrapped Ca2+. The reconstituted channel protein exhibits properties similar to the cyclic GMP-dependent channel observed in excised patches of the plasma membrane and in disk membranes. Cyclic GMP activated the channel cooperatively (Hill coefficient n = 3.1) with an apparent Michaelis constant of approximately 11 microM. After reconstitution of the purified protein into a planar lipid bilayer, we recorded cyclic GMP-stimulated single-channel activity. The single-channel conductance at physiological salt concentrations and in the absence of divalent cations was 26 pS. The drug l-cis-diltiazem, shown to block the cyclic GMP-dependent channel in excised patches of the plasma membrane and in isolated disks of rod outer segments, was ineffective against the purified channel.

Journal ArticleDOI
Horst Vogel1
TL;DR: It is shown that the commonly used set of CD spectra of water-soluble reference proteins is unsuitable to describe the CD specta of alamethicin correctly and therefore the secondary structure ofAlamethiin as derived from CD measurements is at the present state of analysis unreliable.
Abstract: The secondary structure of alamethicin in lipid membranes below and above the lipid phase transition temp. Tt is detd. by Raman spectroscopy and CD measurements. In both cases structural data are obtained by fitting the exptl. spectra by a superposition of the spectra of 15 ref. proteins of known 3-dimensional structure. According to the Raman expts., in a lipid bilayer above Tt, alamethicin is helical from residue 1 to 12, whereas below Tt the helix extends from residue 1 to 16. The remaining C-terminal part is nonhelical up to the end residue 20 both above and below Tt. A considerably lower helix content is derived from CD, namely, 38% and 46% above and below Tt, resp., in agreement with several reported values for CD in the literature. It is shown that the commonly used set of CD spectra of water-sol. ref. proteins is unsuitable to describe the CD spectra of alamethicin correctly. Therefore, the secondary structure of alamethicin as derived from CD measurement is, at the present state of anal., unreliable. In contrast to the case of alamethicin, the CD spectra of melittin in lipid membranes are correctly described by the ref. protein spectra. The helix content of melittin is detd. thereby to be 72% in lipid membranes above Tt and 75% below Tt. The data are in accord with a structure where the hydrophobic part of melittin adopts a bent helix as detd. recently by Raman spectroscopy. The orientation order parameters of the helical parts of alamethicin and of melittin in a lipid membrane are deduced from the difference between a corresponding CD spectrum of a polypeptide in planar multibilayer and that in lipid vesicles. The presented method for detg. helix order parameters is new and may be generally applicable to other membrane proteins. The orientation of the helical part of both polypeptides depends on the phys. state of the lipid bilayer at maximal membrane hydration and in the ordered, lipid state furthermore on the degree of membrane hydration. Under conditions where alamethicin and melittin are incorporated in an aggregated form in a fluid lipid membrane at maximal water content, the helical segments are oriented preferentially parallel to the membrane normal. Cooling such lipid membranes to a temp. below Tt changes the orientation of the helical part of alamethicin as well as melittin toward the membrane plane. On the contrary, in dried planar membranes at 2% water content, both polypeptide mols. are oriented with their helical parts parallel to the membrane normal, similar to the case of fluid lipid membranes. [on SciFinder (R)]