Study Of Biomembranes Research Articles

Biomembranes, ion channels and new biomaterials.

The present consensus view of biomembranes is that of a dynamic structure consisting of a fluid lipid bilayer matrix into which membrane proteins are embedded through hydrophobic and electrostatic interactions. For some years we have been studying the structure of biomembranes and at the same time attempting to use our knowledge of biomembrane structure to develop new types of biomaterial. In this review we present some of our more recent studies of biomembranes and indicate the most recent developments of our studies on biomimetic biomaterials.

Digitalis Research in Berlin–Buch—Retrospective and Perspective Views

Abstract“The following remarks consist partially of matter of fact, and partially of opinion. The former will be permanent; the latter must vary with the detection of error, or the improvement of knowledge. I hazard them with diffidence, and hope they will be examined with candour.” These declarations, which stem from the famous book “An Account of the Foxglove and some of its Medical Uses” by physician William Withering in 1785 in which he introduced preparations from digitalis leaves in the therapy of dropsy (cardiac failure), are cited here by the senior author because of his awareness of the difficulties in presenting a balanced report on his life‐long research project on the further development of digitalis. His decision to devote himself to digitalis research originated at the bedside, when as a physician he experienced the grim final stages of cardiac failure in which no real help for the patients is possible. Unfortunately, his research project did not fit into the research program decreed by the Ministry of Science of the German Democratic Republic, so that he was ordered to stop the digitalis project in favor of biomembrane studies. Fortunately, he got round the ban simply by labeling the digitalis‐like acting steroids as probes for the cell membrane‐located Na+/K+‐transporting ATPase which he had just recognized as the digitalis target (receptor) enzyme. These and other ventures by the authors are collated here for the first time. The aim of this review is to foster straightforward research for solving a major challenge: the development of steroidal drugs for the prevention and cure of cardiac failure.

2′(3α-Benzyloxy-24-norcholan-23-yl)-2′,4′4′-trimethyl-4′,5′-dihydrooxazoline-N-oxyl as a potential spin probe for model membranes

A new steroidal doxyl (4,4-dimethyloxazolidine-N-oxyl) nitroxide (SDN) viz, 2′-(3α-benzyloxy-24-norcholan-2′-yl)-2′,4′4′-trimethyl-4′,5′-dihydrooxazoline-N-oxyl has been synthetized. This is expected to have higher mobility over other spin labels reported earlier. The localization of this spin probe in lipid bilayers has been determined using 1H NMR and 31P NMR techniques. The alterations induced by drugs in the membrane characteristics such as phase transition and permeability have been investigated using electron paramagnetic resonance (EPR) techniques. The results show the applicability of SDN as a potential spin probe in the study of biomembranes.

In Situ Modification of the Phospholipid Environment of Native Rabbit Sarcoplasmic Reticulum Membranes

A water soluble hydrogenation catalyst (palladium di(sodium alizarine monosulphonate)) in a deuterium-containing environment has been used for the in situ insertion of deuterium atoms into the fatty acyl chains of biological membranes. The thermotropic response of the stretching vibrations of the formed C-D bonds, as detected by Fourier transform IR spectroscopy, was used as a selective probe of biological membrane structure. Partial deuteration of unsaturated fatty acyl chains coupled with IR detection potentially provides a means for detecting specific biological roles of particular lipid classes. In the current study of sarcoplasmic reticulum membranes and purified phospholipid/CaATPase vesicles, it is also shown that νC-D monitors change at particular membrane locations which may remain undetected through the CH2 symmetric stretching frequency, a widely used IR spectral parameter. The latter reflects the average environment of the acyl chains. The approach described here may be suitable for wide applications to the study of biomembranes.

Monomolecular layers in the study of biomembranes.

Monomolecular layers have been of great value in the development of concepts of biomembranes. Phospholipids and other amphipathic membrane compounds with a balanced ration between the hydrophobic and hydrophilic part form an oriented monolayer with the polar portion in contact with the aqueous phase and the hydrocarbons extended above. Membrane lipids form insoluble monolayers since the concentration of lipid in the aqueous phase is essentially negligible.

Characterization of magnetically orientable bilayers in mixtures of dihexanoylphosphatidylcholine and dimyristoylphosphatidylcholine by solid-state NMR.

Mixtures of long-chain and short-chain phosphatidylcholine (PC) were characterized by multinuclear (13C, 31P, 2H) solid-state nuclear magnetic resonance. This work complements and extends previous characterization of such mixtures by focusing on concentrated mixtures at temperatures above the gel to liquid crystalline phase transition temperature (Tm) of the long-chain PC component. Above Tm it was observed that highly oriented, bilayer-like assemblies could be formed of mixtures of dimyristoylphosphatidylcholine (DMPC) and dihexanoylphosphatidylcholine (DHPC) in molar ratios ranging from approximately 1:3.5 to 1:2 (DHPC:DMPC) over a considerable range of lipid concentrations (at least 3-40% w/v total lipid, for a 1:2.5 sample). Orientation was observed to occur only in an L alpha-like phase. The NMR data can be accounted for by a general model of the DHPC-DMPC aggregates in which DHPC can be found in two distinct populations (one highly ordered, one not). The averaged conformations of the glycerol backbone/headgroup regions of the long- and short-chain PC composing the assemblies were judged by solid-state 13C NMR to be similar to each other. The information gleaned about these mixtures and the quality of the oriented NMR spectra obtained suggest that DHPC-DMPC mixtures may prove to be useful as model membrane media in solid-state NMR studies of biomembranes.

A procedure for the simultaneous determination of lipid and protein in biomembranes and other biological samples

Very small sample sizes frequently become the limiting factor in biochemical and biomembrane studies in which routine quantification of protein and bulk lipids are required. The procedure described here allows the simultaneous determination of protein and lipid without initial, multiple aliquots. The method is based on the quantitative precipitation of proteins from a defined hexane/isopropanol mixture. The liquid phase resulting after decanting and concentrating to dryness can then be used to assay the lipid content directly. Quantitative assay of protein can be achieved after resuspension of the pelleted material by addition of sodium dodecyl sulfate (0.1%) and deoxycholate (1%). The method is also applicable to other types of lipid- and protein-containing samples with a broad range of protein/lipid ratios and lipid compositions, as they occur, for example, in serum lipoproteins.

Photoionization used as a tool for the study of biomembranes: Fate of tetramethylbenzidine photocation in purple membrane

Photoionization of hydrophobic probes has been developed in micelles or synthetic vesicles. Studies of the yields, compartmentation, and lifetimes of the photo-produced charged species have gathered reliable information on the interfacial and structural properties of these assemblies. Such an approach has never been applied to biological membranes. The present system is tetramethylbenzidine as the probe in native or modified (deionized and/or bleached) purple membrane from halobacteria. The data on photocation formation yields ( ϑ ion) and lifetimes ( τ 1 2 ) allow two main conclusions to be made: (1) tetramethylbenzidine, as the cation, is buried in the membrane core, and (2) its incorporation does not alter the biological activity of the protein. In this biological membrane the photocation lifetime and yield present the same trend of variation with the surface potential but to less of an extent than in model membranes. Bleaching of purple membrane completely modifies the photoionization process and the photocation decay. In addition, these experiments reveal a tight correlation between membrane structure and probe photoionization. Further evidence for structural modification of purple membrane, either by deionization or by bleaching is pointed out.

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2,2,6,6-Tetramethyl piperidine-N-oxyl nitroxyls are known to partition between aqueous and lipid phases, thus serving as probes to study membrane dynamics. The synthesis of a novel steroidal spin label, 3α-hydroxycholan-24-yl-(2″,2″,6″,6″-tetramethyl-N-oxyl)piperidyl butan-1′,4′-dioate, containing 2,2,6,6-tetramethylpiperidine-N-oxyl moiety covalently bonded to the side chain in 3,24-caprostan-diol has been described. The localization of this spin label in model biomembranes has been studied by using electron spin resonance, differential scanning calorimetry, and 1H and 31P NMR spectroscopic techniques. Its applicability in studying the phase transition properties of model membrane l-α-dipalmitoyl phosphatidyl choline in the presence and absence of drugs has been described by using electron spin resonance. The label has also been used to study the permeability of epinephrine into membrane. The results have shown the applicability of the spin label as a potential spin probe in the study of biomembranes.

生体膜研究の進展と展望 物性からみた生体膜

The fluid mosaic model of biomembrane was published in Science 15 years ago. The model was constructed by Singer and Nicolson based on the previous results obtained by thermodynamics, cell biology, spin labeling method, X-ray diffraction, freeze-fracture electron microscopy, differential scanning calorimetry and so on. Almost all knowledges about biomembranes were reflected in the model by their careful consideration. And the basic concept is true even in our day.Since the model appeared, a lot of results have been obtained in the studies of biomembranes. The present review describes the progress and the prospect of biomembrane research by forcusing on the physical properties of biomembranes.In the first section, the author mentions the background of the fluid mosaic model. In the next, the results obtained by various methods are shown with their recent development in the instruments; spin labeling, NMR, X-ray diffraction, fluorometry and electron microscopy. The last section refers three topics which are the structure of membrane protein, the mechanism of stimulus-response coupling in cells, and the micro-domain structure of biomembrane.

Infrared spectroscopic studies of biomembranes and model membranes.

Review Article| March 01 1986 Infrared spectroscopic studies of biomembranes and model membranes David C. Lee; David C. Lee 1Department of Biochemistry and Chemistry, Royal Free Hospital School of Medicine, (University of London), Rowland Hill Street, London, NW3 2PF Search for other works by this author on: This Site PubMed Google Scholar Dennis Chapman Dennis Chapman 1Department of Biochemistry and Chemistry, Royal Free Hospital School of Medicine, (University of London), Rowland Hill Street, London, NW3 2PF Search for other works by this author on: This Site PubMed Google Scholar Biosci Rep (1986) 6 (3): 235–256. https://doi.org/10.1007/BF01115153 Views Icon Views Article contents Figures & tables Video Audio Supplementary Data Peer Review Share Icon Share MailTo Twitter LinkedIn Cite Icon Cite Get Permissions Citation David C. Lee, Dennis Chapman; Infrared spectroscopic studies of biomembranes and model membranes. Biosci Rep 1 March 1986; 6 (3): 235–256. doi: https://doi.org/10.1007/BF01115153 Download citation file: Ris (Zotero) Reference Manager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentAll JournalsBioscience Reports Search Advanced Search Keywords: IR, membranes, protein structure, lipid phase transitions, lipid-protein interactions This content is only available as a PDF. © 1986 Plenum Publishing Corporation1986 Article PDF first page preview Close Modal You do not currently have access to this content.

Effects of 1-anilinonaphthalene-8-sulphonate on phase transition temperature of dipalmitoylphosphatidylcholine liposomes

The effect of 1-anilinonaphthalene-8-sulfonate (ANS) on the thermotropic phase transition of dipalmitoylphosphatidylcholine (DPPC) bilayers was examined by differential scanning calorimetry. The main phase transition temperature was found to be shifted to lower values in the presence of the probe. The shift strongly depends on pH and the presence of salts. This indicates that the penetration of the probe of the hydrocarbon moiety of the bilayer is influenced by coulombic interactions. Pretransition phenomena are also affected. The implications for the interpretation of experimental data of biomembrane studies are discussed.

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The paper considers a thermodynamically consistent phase-field model of a two-phase flow of incompressible viscous fluids. The model allows for a non-linear dependence of the fluid density on the phase-field order parameter. Driven by applications in biomembrane studies, the model is written for tangential flows of fluids constrained to a surface and consists of (surface) Navier–Stokes–Cahn–Hilliard type equations. We apply an unfitted finite element method to discretize the system and introduce a fully discrete time-stepping scheme with the following properties: (i) the scheme decouples the fluid and phase-field equation solvers at each time step, (ii) the resulting two algebraic systems are linear, and (iii) the numerical solution satisfies the same stability bound as the solution of the original system under some restrictions on the discretization parameters. Numerical examples are provided to demonstrate the stability, accuracy, and overall efficiency of the approach. Our computational study of several two-phase surface flows reveals some interesting dependencies of flow statistics on the geometry.

Polymeric phospholipids as new biomaterials.

Phospholipid polymers form a new class of biomaterials with many potential applications in medicine and research. The development of these compounds is based upon the mimicry of cell surfaces and reflects our current understanding of the properties of membrane lipids. Physicochemical characterization of the monomeric, diacetylenic phospholipids illustrates the similarities to naturally occurring lipids, similarities that are confirmed by the capacity to enrich the membranes of A. laidlawii to the level of 90% diacetylenic lipid. Polymerization of diacetylenic phospholipids is easily attained by irradiation and produces a stable, crystalline array. The ability to link membrane lipids covalently permits the isothermal restriction in their motion, and is useful in basic studies of biomembranes. The thromboresistance of polymeric phosphatidylcholines in vitro may be a consequence of the inability of phosphatidylcholines to participate in coagulation. The restricted lateral diffusion of proteins along a polymeric lattice will also inhibit the formation of coagulation complexes. Existing polymers may be altered by a coating of polymeric lipid obtained by the Langmuir-Blodgett method. Polymerized vesicles display significant reductions in permeability and aggregation. Entrapment of soluble materials and reconstitution of membrane proteins may be exploited in controlled and site-directed drug delivery. Polymerization of cells in situ produces "cellular capsules" with entrapped membrane and cellular components. Polymeric hemosomes are capable of gas transport and may function as red cell surrogates. The hybrid qualities of biomembranes (polar surfaces, nonthrombogenic, low antigenic potential, and low permeability) and synthetic polymers (chemical and physical stability) suggest that polymeric phosphatidylcholines may serve as models for biomaterials design.

Absorption and circular dichroism spectroscopies.

The obtaining of absorption and circular dichroism spectra of a suspension of biological membranes is a relatively simple and quick procedure. Extracting correct and meaningful information from these spectra is not so simple and quick. In this chapter an effort will be made stepwise to present the problem of the application to the study of biomembranes of the physical methods of ultraviolet absorption and circular dichroism spectroscopies. This will be approached by first considering solutions, the phenomena that occur and type of information that is available in solution. Next will be considered suspensions of homogeneous particles and how to improve their distorted spectra, and finally the added complication of suspensions of heterogeneous particles (biomembranes) will be noted by presenting data on the three major sources of membrane absorption (lipids, protein side chains, and protein backbone) in several biomembranes and carrying out approximate corrections on experimental ellipticities.

Incorporation of photoreceptor membrane into a multilamellar film

Multilamellar arrays of photoreceptor membrane up to 50 micrometer thick have been produced using a new method. Rhodopsin chromophore orientation in the films was studied using optical linear dichroism. The rhodopsin appears to be structurally intact and capable of photobleaching and regeneration. The production of biologically active liquid-crystal films offers a promising new approach to the study of biomembranes.

Deuterated phospholipids as nonperturbing components for Raman studies of biomembranes

The deuterated phospholipid, 1,2-dipalmitoyl-d62-phosphatidylcholine is shown by Raman spectroscopic measurements to be useful for obtaining information concerning phospholipid conformation in complex phospholipid and lipidprotein mixtures. The Raman bands of the deuterated phospholipid are assigned, and the sensitivity of these vibrational modes to conformational changes in the bilayer is demonstrated. Deuteration of the alkyl chains reveals the CH vibrations of the head group. A change in these bands is observed at the melting temperature and is assigned to alteration of the glycerol backbone conformation upon melting.

生体膜研究におけるNMRの応用

生体膜研究におけるNMRの応用

X-ray diffraction studies of biomembranes

X-ray diffraction studies of biomembranes