Artykuły w czasopismach: „Lipidic model membranes”

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Le Goff, Thomas, Tung B. T. To i Olivier Pierre-Louis. "Shear dynamics of confined membranes". Soft Matter 17, nr 22 (2021): 5467–85. http://dx.doi.org/10.1039/d1sm00322d.

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Inspired by biolubrication, we model the nonlinear dynamics of lipidic membranes sheared between two walls. Several regimes are found with different wrinkle patterns, leading to a non-monotonous contribution of the membrane to the friction force.

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Sejwal, Kushal, Mohamed Chami, Paul Baumgartner, Julia Kowal, Shirley A. Müller i Henning Stahlberg. "Proteoliposomes – a system to study membrane proteins under buffer gradients by cryo-EM". Nanotechnology Reviews 6, nr 1 (1.02.2017): 57–74. http://dx.doi.org/10.1515/ntrev-2016-0081.

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AbstractMembrane proteins are vital to life and major therapeutic targets. Yet, understanding how they function is limited by a lack of structural information. In biological cells, membrane proteins reside in lipidic membranes and typically experience different buffer conditions on both sides of the membrane or even electric potentials and transmembrane gradients across the membranes. Proteoliposomes, which are lipidic vesicles filled with reconstituted membrane proteins, provide an ideal model system for structural and functional studies of membrane proteins under conditions that mimic nature to a certain degree. We discuss methods for the formation of liposomes and proteoliposomes, their imaging by cryo-electron microscopy, and the structural analysis of proteins present in their bilayer. We suggest the formation of ordered arrays akin to weakly ordered two-dimensional (2D) crystals in the bilayer of liposomes as a means to achieve high-resolution, and subsequent buffer modification as a method to capture snapshots of membrane proteins in action.

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Brémaud, Erwan, Cyril Favard i Delphine Muriaux. "Deciphering the Assembly of Enveloped Viruses Using Model Lipid Membranes". Membranes 12, nr 5 (19.04.2022): 441. http://dx.doi.org/10.3390/membranes12050441.

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The cell plasma membrane is mainly composed of phospholipids, cholesterol and embedded proteins, presenting a complex interface with the environment. It maintains a barrier to control matter fluxes between the cell cytosol and its outer environment. Enveloped viruses are also surrounded by a lipidic membrane derived from the host-cell membrane and acquired while exiting the host cell during the assembly and budding steps of their viral cycle. Thus, model membranes composed of selected lipid mixtures mimicking plasma membrane properties are the tools of choice and were used to decipher the first step in the assembly of enveloped viruses. Amongst these viruses, we choose to report the three most frequently studied viruses responsible for lethal human diseases, i.e., Human Immunodeficiency Type 1 (HIV-1), Influenza A Virus (IAV) and Ebola Virus (EBOV), which assemble at the host-cell plasma membrane. Here, we review how model membranes such as Langmuir monolayers, bicelles, large and small unilamellar vesicles (LUVs and SUVs), supported lipid bilayers (SLBs), tethered-bilayer lipid membranes (tBLM) and giant unilamellar vesicles (GUVs) contribute to the understanding of viral assembly mechanisms and dynamics using biophysical approaches.

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Wrobel, Dominika, Dietmar Appelhans, Marco Signorelli, Brigitte Wiesner, Dimitrios Fessas, Ulrich Scheler, Brigitte Voit i Jan Maly. "Interaction study between maltose-modified PPI dendrimers and lipidic model membranes". Biochimica et Biophysica Acta (BBA) - Biomembranes 1848, nr 7 (lipiec 2015): 1490–501. http://dx.doi.org/10.1016/j.bbamem.2015.03.033.

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Castelli, Francesco, Sebastiana Caruso i Nicola Uccella. "Biomimesis of Linolenic Acid Transport through Model Lipidic Membranes by Differential Scanning Calorimetry". Journal of Agricultural and Food Chemistry 51, nr 4 (luty 2003): 851–55. http://dx.doi.org/10.1021/jf020582z.

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Gallová, J., K. Želinská i P. Balgavý. "Partial molecular volumes of cholesterol and phosphatidylcholine in mixed bilayers". European Pharmaceutical Journal 64, nr 2 (27.11.2017): 1–3. http://dx.doi.org/10.1515/afpuc-2017-0012.

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Abstract Dispersion of multilamellar liposomes of dimyristoylphosphatidylcholine (DMPC) and cholesterol (CHOL) were studied by vibrational densitometer for the CHOL mole fractions X = 0−0.54 in the temperature range 18−50 °C, both below and above the main phase transition. DMPC-CHOL bilayers served as a simple model for lipidic part of biological membrane. Volumetric parameters are essential not only to evaluate the data obtained by scattering and diffraction methods on model membranes but can provide valuable information about molecular packing in bilayers and the phase behaviour of lipid-CHOL mixtures. In this paper, preliminary results regarding the changes in the specific volume of lipid bilayer with increasing temperature and CHOL content are presented. Different values of apparent molecular volume of CHOL for different CHOL mole fraction pointed out the non-ideal mixing of DMPC and CHOL.

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Parra, Elisa, Lara H. Moleiro, Ivan López-Montero, Antonio Cruz, Francisco Monroy i Jesús Pérez-Gil. "A combined action of pulmonary surfactant proteins SP-B and SP-C modulates permeability and dynamics of phospholipid membranes". Biochemical Journal 438, nr 3 (26.08.2011): 555–64. http://dx.doi.org/10.1042/bj20110681.

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Proteins SP-B and SP-C are essential to promote formation of surface-active films at the respiratory interface, but their mechanism of action is still under investigation. In the present study we have analysed the effect of the proteins on the accessibility of native, quasi-native and model surfactant membranes to incorporation of the fluorescent probes Nile Red (permeable) and FM 1-43 (impermeable) into membranes. We have also analysed the effect of single or combined proteins on membrane permeation using the soluble fluorescent dye calcein. The fluorescence of FM 1-43 was always higher in membranes containing SP-B and/or SP-C than in protein-depleted membranes, in contrast with Nile Red which was very similar in all of the materials tested. SP-B and SP-C promoted probe partition with markedly different kinetics. On the other hand, physiological proportions of SP-B and SP-C caused giant oligolamellar vesicles to incorporate FM 1-43 from the external medium into apparently most of the membranes instantaneously. In contrast, oligolamellar pure lipid vesicles appeared to be mainly labelled in the outermost membrane layer. Pure lipidic vesicles were impermeable to calcein, whereas it permeated through membranes containing SP-B and/or SP-C. Vesicles containing only SP-B were stable, but prone to vesicle–vesicle interactions, whereas those containing only SP-C were extremely dynamic, undergoing frequent fluctuations and ruptures. Differential structural effects of proteins on vesicles were confirmed by electron microscopy. These results suggest that SP-B and SP-C have different contributions to inter- and intra-membrane lipid dynamics, and that their combined action could provide unique effects to modulate structure and dynamics of pulmonary surfactant membranes and films.

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Trombetta, Domenico, Francesco Castelli, Maria Grazia Sarpietro, Vincenza Venuti, Mariateresa Cristani, Claudia Daniele, Antonella Saija, Gabriela Mazzanti i Giuseppe Bisignano. "Mechanisms of Antibacterial Action of Three Monoterpenes". Antimicrobial Agents and Chemotherapy 49, nr 6 (czerwiec 2005): 2474–78. http://dx.doi.org/10.1128/aac.49.6.2474-2478.2005.

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ABSTRACT In the present paper, we report the antimicrobial efficacy of three monoterpenes [linalyl acetate, (+)menthol, and thymol] against the gram-positive bacterium Staphylococcus aureus and the gram-negative bacterium Escherichia coli. For a better understanding of their mechanisms of action, the capability of these three monoterpenes to damage biomembranes was evaluated by monitoring the release, following exposure to the compounds under study, of the water-soluble fluorescent marker carboxyfluorescein from unilamellar vesicles with different lipidic compositions (phosphatidylcholine, phosphatidylcholine/phosphatidylserine [9:1], phosphatidylcholine/stearylamine [9:1], and phosphatidylglycerol/cardiolipin [9:1]). Furthermore, the interaction of the terpenes tested with dimyristoylphosphatidylcholine multilamellar vesicles as model membranes was monitored by means of differential scanning calorimetry. Finally, the results were related to the relative lipophilicity and water solubility of the compounds examined. Taken together, our findings lead us to speculate that the antimicrobial effect of (+)menthol, thymol, and linalyl acetate may result, at least partially, from a perturbation of the lipid fraction of microorganism plasma membrane, resulting in alterations of membrane permeability and in leakage of intracellular materials. Besides being related to physicochemical characteristics of the drugs (such as lipophilicity and water solubility), this effect seems to be dependent on lipid composition and net surface charge of microbial membranes. Furthermore, the drugs might cross the cell membranes, penetrating into the interior of the cell and interacting with intracellular sites critical for antibacterial activity.

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Castanho, M. A. R. B., S. Lopes i M. Fernandes. "Using UV-Vis. Linear Dichroism to Study the Orientation of Molecular Probes and Biomolecules in Lipidic Membranes". Spectroscopy 17, nr 2-3 (2003): 377–98. http://dx.doi.org/10.1155/2003/801452.

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Linear dichroism methodologies are based on the different interaction of molecules with linearly polarized light depending on their orientation. Theoretical predictions are used to conclude on the orientation of selected molecules relative to their neighbours (usually an organized matrix). In the specific case of linear dichroism methodologies applied to data obtained from UV-Vis. spectroscopic techniques, the orientational distribution function of the chromophores' electronic transition moment can be calculated and converted to the molecular axis distribution function. In this paper, the orientation of molecular probes and biomolecules in model systems of biomembranes (lipidic matrixes) is explored and illustrated using common membrane probes (trans-parinaric acid, a cyanine and laurdan) and polyene antibiotics (Amphotericin B and Nystatin). The emphasis is on the technique and methodologies themselves, rather than the scientific impact of the attained distributions. The main addressed items are: (1) How to adapt a common UV-Vis. spectrophotometer and spectrofluorimeter to perform linear dicrhoism experiments?, (2) Sample preparation, and (3) Data analysis (including artefacts corrections).

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Mori, Kenichi, Yosuke Imai, Tsubasa Takaoka, Koji Iwamoto, Hideyoshi Fuji i Tyuji Hoshino. "2P270 Database of Lipid Membrane Structures : Computational Analyses of Model Membranes(40. Membrane structure,Poster Session,Abstract,Meeting Program of EABS & BSJ 2006)". Seibutsu Butsuri 46, supplement2 (2006): S363. http://dx.doi.org/10.2142/biophys.46.s363_2.

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Han, Xu, Chih-Chia Su, Zhemin Zhang, Meinan Lyu, Edward Yu i Marvin T. Nieman. "Elucidating the Structural Dynamics of Integrin α IIbβ 3 from Native Platelet Membranes By Cryo-EM Coupled with Build and Retrieve Data Processing Methodology". Blood 142, Supplement 1 (28.11.2023): 2559. http://dx.doi.org/10.1182/blood-2023-178888.

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Background: Platelets play a critical role in physiological processes by sensing the extracellular environment through their membrane proteins. Changing the quantity or quality of these proteins can profoundly affect platelet physiology and impact health. The native membrane environment provides essential additional regulatory cues that impact the protein structure and mechanism of action. Single-particle cryogenic electron microscopy (cryo-EM) has transformed structural biology by allowing high-resolution structures of membrane proteins and large macromolecules to be solved from highly purified, homogeneous samples. Our recent breakthroughs in data processing make it feasible to obtain high-resolution protein structures from crude preparations in their native environments by integrating cryo-EM with the novel “Build and Retrieve” (BaR) data processing methodology. By performing in silico purification, image sorting, and model building from large heterogenous datasets, this iterative bottom-up methodology opens new avenues for an in-depth systems biology approach with structural biology that will uncover how the native environment, including lipid and metal binding, post-translational modifications, and co-factor associations regulate platelet function at the molecular level. Method: Whole blood was collected, and the platelet membrane proteins were solubilized by 1% n-Dodecyl-β-D-Maltoside (DDM) and incorporated into lipidic nanodisc MSP1E3D1 directly from the endogenous source. After being enriched by size exclusion chromatography, the mixture of proteins at ~200 kDa was directly applied on cryo-EM grids. Data were collected on Titan Krios G3i cryogenic transmission electron microscope equipped with a BioQuantum K3 camera. All data processing was done in cryoSPARC using the BaR protocol. The near-atomic-resolution cryo-EM maps were used for protein identification using the program phenix.sequence_from_map in the PHENIX suite. The final protein models were built by Coot and refined by PHENIX. Results: We have used using cryo-EM followed by the BaR method to solve the first unmodified integrin α IIbβ 3 structure directly from resting human platelet membranes in its inactivated and intermediate states at 2.76Å and 2.49Å, respectively. From these two structures, we observed the ion binding sites at the β1-domain and β-propeller domain in agreement with previous “classical” α IIbβ 3 structural studies using a purified sample. More importantly, we were able to assign endogenous N-linked glycan sites, which reflected how glycosylation naturally regulates α IIbβ 3 dynamic and function on resting human platelets. Finally, we also solved a novel third unique dimer conformation of α IIbβ 3 at 2.61Å formed by two intermediate-states of α IIbβ 3. This may indicate a previously unknown self-regulatory mechanism of α IIbβ 3 in its native environment. Conclusion: In conclusion, our data show the power of using cryo-EM with the BaR method to uncover novel structures directly from natural sources to identify unrecognized regulation mechanisms for proteins without artifacts due to purification processes. A distinct advantage of the BaR method is that it is an unbiased approach for solving multiple structures from raw samples, which highlights the potential of building a protein structural atlas from platelets. These data have the potential to enrich our understanding of platelet signaling circuitry and foster the development of higher-quality diagnoses and treatments for patients with platelet disorders.

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Speziale, Chiara, Livia Salvati Manni, Cristina Manatschal, Ehud M. Landau i Raffaele Mezzenga. "A macroscopic H+and Cl−ions pump via reconstitution of EcClC membrane proteins in lipidic cubic mesophases". Proceedings of the National Academy of Sciences 113, nr 27 (16.06.2016): 7491–96. http://dx.doi.org/10.1073/pnas.1603965113.

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Functional reconstitution of membrane proteins within lipid bilayers is crucial for understanding their biological function in living cells. While this strategy has been extensively used with liposomes, reconstitution of membrane proteins in lipidic cubic mesophases presents significant challenges related to the structural complexity of the lipid bilayer, organized on saddle-like minimal surfaces. Although reconstitution of membrane proteins in lipidic cubic mesophases plays a prominent role in membrane protein crystallization, nanotechnology, controlled drug delivery, and pathology of diseased cells, little is known about the molecular mechanism of protein reconstitution and about how transport properties of the doped mesophase mirror the original molecular gating features of the reconstituted membrane proteins. In this work we design a general strategy to demonstrate correct functional reconstitution of active and selective membrane protein transporters in lipidic mesophases, exemplified by the bacterial ClC exchanger fromEscherichia coli(EcClC) as a model ion transporter. We show that its correct reconstitution in the lipidic matrix can be used to generate macroscopic proton and chloride pumps capable of selectively transporting charges over the length scale of centimeters. By further exploiting the coupled chloride/proton exchange of this membrane protein and by combining parallel or antiparallel chloride and proton gradients, we show that the doped mesophase can operate as a charge separation device relying only on the reconstituted EcClC protein and an external bias potential. These results may thus also pave the way to possible applications in supercapacitors, ion batteries, and molecular pumps.

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Blakeslee, Joshua J., Eun-Hyang Han, Yun Lin, Jinshan Lin, Seema Nath, Liwen Zhang, Zhenyu Li i Katrina Cornish. "Proteomic and Targeted Lipidomic Analyses of Fluid and Rigid Rubber Particle Membrane Domains in Guayule". Plants 13, nr 21 (24.10.2024): 2970. http://dx.doi.org/10.3390/plants13212970.

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Rubber (cis-1,4-polyisoprene) is produced in cytosolic unilamellar vesicles called rubber particles (RPs), and the protein complex responsible for this synthesis, the rubber transferase (RTase), is embedded in, or tethered to, the membranes of these RPs. Solubilized enzyme activity is very difficult to achieve because the polymerization of highly hydrophilic substrates into hydrophobic polymers requires a polar/non-polar interface and a hydrophobic compartment. Using guayule (Parthenium argentatum) as a model rubber-producing species, we optimized methods to isolate RP unilamellear membranes and then a subset of membrane microdomains (detergent-resistant membranes) likely to contain protein complexes such as RTase. The phospholipid and sterol composition of these membranes and microdomains were analyzed using thin-layer chromatography (TLC) and liquid chromatography tandem mass spectroscopy (LC-MS/MS). Our data indicate that RP membranes consist predominantly of phosphatidic acid-containing membrane microdomains (DRMs or “lipid rafts”). Proteomic analyses of guayule RP membranes and membrane microdomains identified 80 putative membrane proteins covering 30 functional categories. From this population, we have tentatively identified several proteins in multiple functional domains associated with membrane microdomains which may be critical to RTase function. Definition of the mechanisms underlying rubber synthesis will provide targets for both metabolic engineering and breeding strategies designed to increase natural rubber production in latex-producing species.

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Basañez, Gorka, Juanita C. Sharpe, Jennifer Galanis, Teresa B. Brandt, J. Marie Hardwick i Joshua Zimmerberg. "Bax-type Apoptotic Proteins Porate Pure Lipid Bilayers through a Mechanism Sensitive to Intrinsic Monolayer Curvature". Journal of Biological Chemistry 277, nr 51 (14.10.2002): 49360–65. http://dx.doi.org/10.1074/jbc.m206069200.

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During apoptosis, Bax-type proteins permeabilize the outer mitochondrial membrane to release intermembrane apoptogenic factors into the cytosol via a poorly understood mechanism. We have proposed that Bax and ΔN76Bcl-xL(the Bax-like cleavage fragment of Bcl-xL) function by forming pores that are at least partially composed of lipids (lipidic pore formation). Since the membrane monolayer must bend during lipidic pore formation, we here explore the effect of intrinsic membrane monolayer curvature on pore formation. Nonlamellar lipids with positive intrinsic curvature such as lysophospholipids promoted membrane permeabilization, whereas nonlamellar lipids with negative intrinsic curvature such as diacylglycerol and phosphatidylethanolamine inhibited membrane permeabilization. The differential effects of nonlamellar lipids on membrane permeabilization were not correlated with lipid-induced changes in membrane binding or insertion of Bax or ΔN76Bcl-xL. Altogether, these results are consistent with a model whereby Bax-type proteins change the bending propensity of the membrane to form pores comprised at least in part of lipids in a structure of net positive monolayer curvature.

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Sadchenko, A. O. "Correlations between molecular parameters of guest substances and their effect on model lipid membranes". Functional materials 23, nr 2 (15.06.2016): 230–35. http://dx.doi.org/10.15407/fm23.02.230.

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Polovinkin, Vitaly, Krishna Khakurel, Michal Babiak, Borislav Angelov, Bohdan Schneider, Jan Dohnalek, Jakob Andreasson i Janos Hajdu. "Demonstration of electron diffraction from membrane protein crystals grown in a lipidic mesophase after lamella preparation by focused ion beam milling at cryogenic temperatures". Journal of Applied Crystallography 53, nr 6 (13.10.2020): 1416–24. http://dx.doi.org/10.1107/s1600576720013096.

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Electron crystallography of sub-micrometre-sized 3D protein crystals has emerged recently as a valuable field of structural biology. In meso crystallization methods, utilizing lipidic mesophases, particularly lipidic cubic phases (LCPs), can produce high-quality 3D crystals of membrane proteins (MPs). A major step towards realizing 3D electron crystallography of MP crystals, grown in meso, is to demonstrate electron diffraction from such crystals. The first task is to remove the viscous and sticky lipidic matrix that surrounds the crystals without damaging the crystals. Additionally, the crystals have to be thin enough to let electrons traverse them without significant multiple scattering. In the present work, the concept that focused ion beam milling at cryogenic temperatures (cryo-FIB milling) can be used to remove excess host lipidic mesophase matrix is experimentally verified, and then the crystals are thinned to a thickness suitable for electron diffraction. In this study, bacteriorhodopsin (BR) crystals grown in a lipidic cubic mesophase of monoolein were used as a model system. LCP from a part of a hexagon-shaped plate-like BR crystal (∼10 µm in thickness and ∼70 µm in the longest dimension), which was flash-frozen in liquid nitrogen, was milled away with a gallium FIB under cryogenic conditions, and a part of the crystal itself was thinned into a ∼210 nm-thick lamella with the ion beam. The frozen sample was then transferred into an electron cryo-microscope, and a nanovolume of ∼1400 × 1400 × 210 nm of the BR lamella was exposed to 200 kV electrons at a fluence of ∼0.06 e Å−2. The resulting electron diffraction peaks were detected beyond 2.7 Å resolution (with an average peak height to background ratio of >2) by a CMOS-based Ceta 16M camera. The results demonstrate that cryo-FIB milling produces high-quality lamellae from crystals grown in lipidic mesophases and pave the way for 3D electron crystallography on crystals grown or embedded in highly viscous media.

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Vashchenko, O. V. "Comparative effects of stearic acid, calcium and magnesium stearates as dopants in model lipid membranes". Functional materials 25, nr 2 (27.06.2018): 300–307. http://dx.doi.org/10.15407/fm25.02.300.

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ANGELOV, BORISLAV. "PROTEIN NANODOMAIN PATTERNS IN LIPIDIC BICONTINUOUS CUBIC PHASES". Modern Physics Letters B 16, nr 07 (20.03.2002): 225–30. http://dx.doi.org/10.1142/s0217984902003683.

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Ordered nanopatterns that match to the {6, 4} tiling of the diamond type infinite periodic minimal surface are generated. The construction of the unit cell, generally recognized as a Monkey Saddle, is done numerically using the exact Weierstrass–Enneper representation of minimal surfaces. The obtained patterns are a good model for the self-assembly nanodomain organizations of membrane proteins, compatible with 3- or 6-fold symmetries and formed upon reconstitution in bicontinuous cubic lipid phases.

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Lee, David B. N., Nora Jamgotchian, Suni G. Allen, Michael B. Abeles i Harry J. Ward. "A lipid-protein hybrid model for tight junction". American Journal of Physiology-Renal Physiology 295, nr 6 (grudzień 2008): F1601—F1612. http://dx.doi.org/10.1152/ajprenal.00097.2008.

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The epithelial tight junction (TJ) was first described ultrastructurally as a fusion of the outer lipid leaflets of the adjoining cell membrane bilayers (hemifusion). The discovery of an increasing number of integral TJ and TJ-associated proteins has eclipsed the original lipid-based model with the wide acceptance of a protein-centric model for the TJ. In this review, we stress the importance of lipids in TJ structure and function. A lipid-protein hybrid model accommodates a large body of information supporting the lipidic characteristics of the TJ, harmonizes with the accumulating evidence supporting the TJ as an assembly of lipid rafts, and focuses on an important, but relatively unexplored, field of lipid-protein interactions in the morphology, physiology, and pathophysiology of the TJ.

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Cort, Aysegul, Tomris Ozben, Anna Sansone, Sebastian Barata-Vallejo, Chryssostomos Chatgilialoglu i Carla Ferreri. "Bleomycin-induced trans lipid formation in cell membranes and in liposome models". Organic & Biomolecular Chemistry 13, nr 4 (2015): 1100–1105. http://dx.doi.org/10.1039/c4ob01924e.

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Bleomycin–iron complexes cause lipidcis–transisomerisation through thiyl radical formation and reactivity with unsaturated phospholipids, revealing membranes as a relevant and novel site of drug effect.

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Kehlenbeck, Dominique-Maurice, Inokentijs Josts, Julius Nitsche, Sebastian Busch, V. Trevor Forsyth i Henning Tidow. "Comparison of lipidic carrier systems for integral membrane proteins – MsbA as case study". Biological Chemistry 400, nr 11 (26.11.2019): 1509–18. http://dx.doi.org/10.1515/hsz-2019-0171.

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Abstract Membrane protein research suffers from the drawback that detergents, which are commonly used to solubilize integral membrane proteins (IMPs), often lead to protein instability and reduced activity. Recently, lipid nanodiscs (NDs) and saposin-lipoprotein particles (Salipro) have emerged as alternative carrier systems that keep membrane proteins in a native-like lipidic solution environment and are suitable for biophysical and structural studies. Here, we systematically compare nanodiscs and Salipros with respect to long-term stability as well as activity and stability of the incorporated membrane protein using the ABC transporter MsbA as model system. Our results show that both systems are suitable for activity measurements as well as structural studies in solution. Based on our results we suggest screening of different lipids with respect to activity and stability of the incorporated IMP before performing structural studies.

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Essaid, Donia, Véronique Rosilio, Katia Daghildjian, Audrey Solgadi, Juliette Vergnaud, Athena Kasselouri i Pierre Chaminade. "Artificial plasma membrane models based on lipidomic profiling". Biochimica et Biophysica Acta (BBA) - Biomembranes 1858, nr 11 (listopad 2016): 2725–36. http://dx.doi.org/10.1016/j.bbamem.2016.07.010.

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Pušenjak, Rudolf, i Maks Oblak. "Simulacija akcijskega potenciala v Hodgkin-Huxleyevem modelu". Anali PAZU 1, nr 2 (10.05.2022): 122–27. http://dx.doi.org/10.18690/analipazu.1.2.122-127.2011.

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Vzdražljive (ekscitabilne) celice se imenujejo celice, ki so sposobne proizvajati akcijske potenciale. Akcijski potenciali nastajajojo v nevronih in mišicah v obliki signalov. Signalni mehanizem povzroča možgansko aktivnost oziroma krčenje mišic. Lipidni plasti celične membrane se obnašata kot kondenzator, spremenljive prevodnosti membrane za posamezne ione pa so posledica ionskih kanalov, ki se lahko odpirajo ali zapirajo in s tem bolje ali slabše prevajajo. Na tej osnovi lahko celično membrano modeliramo kot električno vezje. V članku je predstavljena izpeljava enačb Hodgkin-Huxleyevega modela celične membrane s pomočjo osnovnih zakonov elektrotehnike in kinetike prvega reda. Dobljeni matematični model celične membrane je uporabljen za simulacijo akcijskega potenciala s simboličnim programskim orodjem Mathematica®.

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Lee, JinKeun, i Barry R. Lentz. "Evolution of Lipidic Structures during Model Membrane Fusion and the Relation of This Process to Cell Membrane Fusion†". Biochemistry 36, nr 21 (maj 1997): 6251–59. http://dx.doi.org/10.1021/bi970404c.

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Renno, Giacomo, Francesca Cardano, Giorgio Volpi, Claudia Barolo, Guido Viscardi i Andrea Fin. "Imidazo[1,5-a]pyridine-Based Fluorescent Probes: A Photophysical Investigation in Liposome Models". Molecules 27, nr 12 (16.06.2022): 3856. http://dx.doi.org/10.3390/molecules27123856.

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Imidazo[1,5-a]pyridine is a stable scaffold, widely used for the development of emissive compounds in many application fields (e.g., optoelectronics, coordination chemistry, sensors, chemical biology). Their compact shape along with remarkable photophysical properties make them suitable candidates as cell membrane probes. The study of the membrane dynamics, hydration, and fluidity is of importance to monitor the cellular health and to explore crucial biochemical pathways. In this context, five imidazo[1,5-a]pyridine-based fluorophores were synthesized according to a one-pot cyclization between an aromatic ketone and benzaldehyde in the presence of ammonium acetate and acetic acid. The photophysical features of prepared compounds were investigated in several organic solvents and probes 2–4 exhibited the greatest solvatochromic behavior, resulting in a higher suitability as membrane probes. Their interaction with liposomes as artificial membrane model was tested showing a successful intercalation of the probes in the lipid bilayer. Kinetic experiments were carried out and the lipidic phase influence on the photophysical features was evaluated through temperature-dependent experiments. The results herein reported encourage further investigations on the use of imidazo[1,5-a]pyridine scaffold as fluorescent membrane probes.

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de Souza Teixeira, Leonardo, Tatiana Vila Chagas, Antonio Alonso, Isabel Gonzalez-Alvarez, Marival Bermejo, James Polli i Kênnia Rocha Rezende. "Biomimetic Artificial Membrane Permeability Assay over Franz Cell Apparatus Using BCS Model Drugs". Pharmaceutics 12, nr 10 (19.10.2020): 988. http://dx.doi.org/10.3390/pharmaceutics12100988.

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A major parameter controlling the extent and rate of oral drug absorption is permeability through the lipid bilayer of intestinal epithelial cells. Here, a biomimetic artificial membrane permeability assay (Franz–PAMPA Pampa) was validated using a Franz cells apparatus. Both high and low permeability drugs (metoprolol and mannitol, respectively) were used as external standards. Biomimetic properties of Franz–PAMPA were also characterized by electron paramagnetic resonance spectroscopy (EPR). Moreover, the permeation profile for eight Biopharmaceutic Classification System (BCS) model drugs cited in the FDA guidance and another six drugs (acyclovir, cimetidine, diclofenac, ibuprofen, piroxicam, and trimethoprim) were measured across Franz–PAMPA. Apparent permeability (Papp) Franz–PAMPA values were correlated with fraction of dose absorbed in humans (Fa%) from the literature. Papp in Caco-2 cells and Corti artificial membrane were likewise compared to Fa% to assess Franz–PAMPA performance. Mannitol and metoprolol Papp values across Franz–PAMPA were lower (3.20 × 10−7 and 1.61 × 10−5 cm/s, respectively) than those obtained across non-impregnated membrane (2.27 × 10−5 and 2.55 × 10−5 cm/s, respectively), confirming lipidic barrier resistivity. Performance of the Franz cell permeation apparatus using an artificial membrane showed acceptable log-linear correlation (R2 = 0.664) with Fa%, as seen for Papp in Caco-2 cells (R2 = 0.805). Data support the validation of the Franz–PAMPA method for use during the drug discovery process.

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Yaghmur, Anan, Barbara Sartori i Michael Rappolt. "The role of calcium in membrane condensation and spontaneous curvature variations in model lipidic systems". Phys. Chem. Chem. Phys. 13, nr 8 (2011): 3115–25. http://dx.doi.org/10.1039/c0cp01036g.

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Nomura, Kaoru, Gilles Ferrat, Terumi Nakajima, Herve Darbon, Takashi Iwashita i Gerardo Corzo. "S1h1-5 Interactions of two kinds of arthropods-derived antimicrobial peptides, pandinins and oxyopinins, with model lipid membranes(S1-h1 "Antimicrobial Peptides and Membrane Interactions",Symposia,Abstract,Meeting Program of EABS & BSJ 2006)". Seibutsu Butsuri 46, supplement2 (2006): S113. http://dx.doi.org/10.2142/biophys.46.s113_3.

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Morigaki, Kenichi. "S1e2-8 Micropatterned composite membranes of polymerized and fluid lipid bilayers as a versatile model cellular membrane(S1-e2: "New Biomembrane Model Systems, Giant Liposomes and Supported Planar Bilayers, for Probing Biomembrane Structure and Function, and Creation of De Novo Functional Membrane System",Symposia,Abstract,Meeting Program of EABS & BSJ 2006)". Seibutsu Butsuri 46, supplement2 (2006): S118. http://dx.doi.org/10.2142/biophys.46.s118_4.

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Borshchevskiy, Valentin, Rouslan Efremov, Ekaterina Moiseeva, Georg Büldt i Valentin Gordeliy. "Overcoming merohedral twinning in crystals of bacteriorhodopsin grown in lipidic mesophase". Acta Crystallographica Section D Biological Crystallography 66, nr 1 (21.12.2009): 26–32. http://dx.doi.org/10.1107/s0907444909042838.

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Twinning is one of the most common crystal-growth defects in protein crystallography. There are neither efficient rational approaches for the growth of nontwinned protein crystals nor are there examples of systematic studies of the dependence of the twinning-ratio distribution on crystallization conditions. The description of the twinning phenomenon has been covered even less for membrane-protein crystals and is non-existent for crystals grown using lipidic phases (in meso). In the present work, possibilities for overcoming merohedral twinning are investigated for crystals of the membrane protein bacteriorhodopsin (bR) grownin meso. It is shown that traditional crystallization additives are not effective in the case of thein mesocrystallization of bR. The twinning ratio was determined for 310 crystals grown under different crystallization conditions. A correlation of the twinning ratio with the growth rate of the crystals was observed. Slow growth indicated that crystals had a noticeable chance of avoiding twinning. Model calculations were performed in order to rationalize this observation. The calculations confirmed the experimental observation that most crystals consist of two twin domains and showed that under this condition small changes in the probability of twin-domain formation lead to dramatic changes in the number of nontwinned crystals, which explains why slow crystal growth results in a considerable number of nontwinned crystals.

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31

Zatloukalova, Martina, Ewa Nazaruk i Renata Bilewicz. "Electrogenic transport of Na+/K+-ATPase incorporated in lipidic cubic phases as a model biomimetic membrane". Electrochimica Acta 310 (lipiec 2019): 113–21. http://dx.doi.org/10.1016/j.electacta.2019.04.082.

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Vandoolaeghe, Pauline, Adrian R. Rennie, Richard A. Campbell, Robert K. Thomas, Fredrik Höök, Giovanna Fragneto, Justas Barauskas, Fredrik Tiberg i Tommy Nylander. "The Delivery of Lipidic Compounds to Model Membrane Interfaces by Non-lamellar Liquid Crystalline Nano-particles". Biophysical Journal 96, nr 3 (luty 2009): 19a. http://dx.doi.org/10.1016/j.bpj.2008.12.1000.

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Ito, Koreaki, Naomi Shimokawa-Chiba i Shinobu Chiba. "Sec translocon has an insertase-like function in addition to polypeptide conduction through the channel". F1000Research 8 (20.12.2019): 2126. http://dx.doi.org/10.12688/f1000research.21065.1.

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The Sec translocon provides a polypeptide-conducting channel, which is insulated from the hydrophobic lipidic environment of the membrane, for translocation of hydrophilic passenger polypeptides. Its lateral gate allows a downstream hydrophobic segment (stop-transfer sequence) to exit the channel laterally for integration into the lipid phase. We note that this channel model only partly accounts for the translocon function. The other essential role of translocon is to facilitate de novo insertion of the N-terminal topogenic segment of a substrate polypeptide into the membrane. Recent structural studies suggest that de novo insertion does not use the polypeptide-conducting channel; instead, it takes place directly at the lateral gate, which is prone to opening. We propose that the de novo insertion process, in concept, is similar to that of insertases (such as YidC in bacteria and EMC3 in eukaryotes), in which an intramembrane surface of the machinery provides the halfway point of insertion.

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Vasco, Aldrin V., Martina Brode, Yanira Méndez, Oscar Valdés, Daniel G. Rivera i Ludger A. Wessjohann. "Synthesis of Lactam-Bridged and Lipidated Cyclo-Peptides as Promising Anti-Phytopathogenic Agents". Molecules 25, nr 4 (13.02.2020): 811. http://dx.doi.org/10.3390/molecules25040811.

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Antimicrobial resistance to conventional antibiotics and the limited alternatives to combat plant-threatening pathogens are worldwide problems. Antibiotic lipopeptides exert remarkable membrane activity, which usually is not prone to fast resistance formation, and often show organism-type selectivity. Additional modes of action commonly complement the bioactivity profiles of such compounds. The present work describes a multicomponent-based methodology for the synthesis of cyclic polycationic lipopeptides with stabilized helical structures. The protocol comprises an on solid support Ugi-4-component macrocyclization in the presence of a lipidic isocyanide. Circular dichroism was employed to study the influence of both macrocyclization and lipidation on the amphiphilic helical structure in water and micellar media. First bioactivity studies against model phytopathogens demonstrated a positive effect of the lipidation on the antimicrobial activity.

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SILVA JUNIOR, IZAN M., MARIA CLÍCIA S. CASTRO, DILSON SILVA i CÉLIA M. CORTEZ. "Relevance of Hydrodynamic Effects for the Calculation of Outer Surface Potential of Biological Membrane Using Electrophoretic Data". Anais da Academia Brasileira de Ciências 88, nr 2 (7.06.2016): 751–63. http://dx.doi.org/10.1590/0001-3765201620140530.

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ABSTRACT In this paper, we present the results of a study on the influence of hydrodynamic effects on the surface potentials of the erythrocyte membrane, comparing two different models formulated to simulate the electrophoretic movement of a biological cell: the classical Helmholtz-Smoluchowski model and a model presented by Hsu et al. (1996). This model considers hydrodynamic effects to describe the distribution of the fluid velocity. The electric potential equation was obtained from the non-linear Poisson-Boltzmann equation, considering the spatial distribution of electrical charges fixed in glycocalyx and cytoplasmic proteins, as well as electrolyte charges and ones fixed on the surfaces of lipidic bilayer. Our results show that the Helmholtz-Smoluchowski model is not able to reflect the real forces responsible to the electrophoretic behavior of cell, because it does not take account the hydrodynamic effects of glycocalyx. This charged network that covers cellular surface constitutes a complex physical system whose electromechanical characteristics cannot be neglected. Then, supporting the hypothesis of other authors, we suggest that, in electrophoretic motion analyses of cells, the classical model represents a limiting case of models that take into account hydrodynamic effects to describe the velocity distribution of fluid.

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Sunami, Takeshi, Kazufumi Hosoda, Hiroaki Suzuki, Tomoaki Matsuura i Tetsuya Yomo. "Cellular Compartment Model for Exploring the Effect of the Lipidic Membrane on the Kinetics of Encapsulated Biochemical Reactions". Langmuir 26, nr 11 (czerwiec 2010): 8544–51. http://dx.doi.org/10.1021/la904569m.

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Trampari, Sofia, Caroline Neumann, Samuel J. Hjorth-Jensen, Azadeh Shahsavar, Esben M. Quistgaard i Poul Nissen. "Insights into the mechanism of high lipid–detergent crystallization of membrane proteins". Journal of Applied Crystallography 54, nr 6 (25.11.2021): 1775–83. http://dx.doi.org/10.1107/s1600576721010669.

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Obtaining well diffracting crystals of membrane proteins is often challenging, but chances can be improved by crystallizing them in lipidic conditions that mimic their natural membrane environments. One approach is the high lipid–detergent (HiLiDe) method, which works by mixing the target protein with high concentrations of lipid and detergent prior to crystallization. Although this approach is convenient and flexible, understanding the effects of systematically varying lipid/detergent ratios and a characterization of the lipid phases that form during crystallization would be useful. Here, a HiLiDe phase diagram is reported for the model membrane protein MhsT, which tracks the precipitation and crystallization zones as a function of lipid and detergent concentrations, and is augmented with data on crystal sizes and diffraction properties. Additionally, the crystallization of SERCA1a solubilized directly with native lipids is characterized as a function of detergent concentration. Finally, HiLiDe crystallization drops are analysed with transmission electron microscopy, which among other features reveals liposomes, stacked lamellae that may represent crystal precursors, and mature crystals with clearly discernible packing arrangements. The results emphasize the significance of optimizing lipid/detergent ratios over broad ranges and provide insights into the mechanism of HiLiDe crystallization.

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Bozzer, Sara, Michele Dal Bo, Giuseppe Toffoli, Paolo Macor i Sara Capolla. "Nanoparticles-Based Oligonucleotides Delivery in Cancer: Role of Zebrafish as Animal Model". Pharmaceutics 13, nr 8 (21.07.2021): 1106. http://dx.doi.org/10.3390/pharmaceutics13081106.

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Oligonucleotide (ON) therapeutics are molecular target agents composed of chemically synthesized DNA or RNA molecules capable of inhibiting gene expression or protein function. How ON therapeutics can efficiently reach the inside of target cells remains a problem still to be solved in the majority of potential clinical applications. The chemical structure of ON compounds could affect their capability to pass through the plasma membrane. Other key factors are nuclease degradation in the extracellular space, renal clearance, reticulo-endothelial system, and at the target cell level, the endolysosomal system and the possible export via exocytosis. Several delivery platforms have been proposed to overcome these limits including the use of lipidic, polymeric, and inorganic nanoparticles, or hybrids between them. The possibility of evaluating the efficacy of the proposed therapeutic strategies in useful in vivo models is still a pivotal need, and the employment of zebrafish (ZF) models could expand the range of possibilities. In this review, we briefly describe the main ON therapeutics proposed for anticancer treatment, and the different strategies employed for their delivery to cancer cells. The principal features of ZF models and the pros and cons of their employment in the development of ON-based therapeutic strategies are also discussed.

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39

Cornell, Bruce A. "S1e2-5 Immunosensors based on Tethered Lipid Membranes(S1-e2: "New Biomembrane Model Systems, Giant Liposomes and Supported Planar Bilayers, for Probing Biomembrane Structure and Function, and Creation of De Novo Functional Membrane System",Symposia,Abstract,Meeting Program of EABS & BSJ 2006)". Seibutsu Butsuri 46, supplement2 (2006): S118. http://dx.doi.org/10.2142/biophys.46.s118_1.

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Romano, Eugenia, Paolo Antonio Netti i Enza Torino. "A High Throughput Approach Based on Dynamic High Pressure for the Encapsulation of Active Compounds in Exosomes for Precision Medicine". International Journal of Molecular Sciences 22, nr 18 (13.09.2021): 9896. http://dx.doi.org/10.3390/ijms22189896.

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In recent decades, endogenous nanocarrier-exosomes have received considerable scientific interest as drug delivery systems. The unique proteo-lipid architecture allows the crossing of various natural barriers and protects exosomes cargo from degradation in the bloodstream. However, the presence of this bilayer membrane as well as their endogenous content make loading of exogenous molecules challenging. In the present work, we will investigate how to promote the manipulation of vesicles curvature by a high-pressure microfluidic system as a ground-breaking method for exosomes encapsulation. Exosomes isolated from Uppsala 87 Malignant Glioma (U87-MG) cell culture media were characterized before and after the treatment with high-pressure homogenization. Once their structural and biological stability were validated, we applied this novel method for the encapsulation in the lipidic exosomal bilayer of the chemotherapeutic Irinotecan HCl Trihydrate-CPT 11. Finally, we performed in vitro preliminary test to validate the nanobiointeraction of exosomes, uptake mechanisms, and cytotoxic effect in cell culture model.

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41

Taniguchi, Emi, Katsuyuki Nishimura i Akira Naito. "1P346 Conformation and interaction of β-endorphin with a model membrane consisting of unsaturated lipid bilayers as studied by solid-state NMR(12. Membrane dynamics,Poster Session,Abstract,Meeting Program of EABS & BSJ 2006)". Seibutsu Butsuri 46, supplement2 (2006): S233. http://dx.doi.org/10.2142/biophys.46.s233_2.

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Pan, Dongqing, Ryo Oyama, Tomomi Sato, Takanori Nakane, Ryo Mizunuma, Keita Matsuoka, Yasumasa Joti i in. "Crystal structure of CmABCB1 multi-drug exporter in lipidic mesophase revealed by LCP-SFX". IUCrJ 9, nr 1 (23.12.2021): 134–45. http://dx.doi.org/10.1107/s2052252521011611.

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CmABCB1 is a Cyanidioschyzon merolae homolog of human ABCB1, a well known ATP-binding cassette (ABC) transporter responsible for multi-drug resistance in various cancers. Three-dimensional structures of ABCB1 homologs have revealed the snapshots of inward- and outward-facing states of the transporters in action. However, sufficient information to establish the sequential movements of the open–close cycles of the alternating-access model is still lacking. Serial femtosecond crystallography (SFX) using X-ray free-electron lasers has proven its worth in determining novel structures and recording sequential conformational changes of proteins at room temperature, especially for medically important membrane proteins, but it has never been applied to ABC transporters. In this study, 7.7 monoacylglycerol with cholesterol as the host lipid was used and obtained well diffracting microcrystals of the 130 kDa CmABCB1 dimer. Successful SFX experiments were performed by adjusting the viscosity of the crystal suspension of the sponge phase with hydroxypropyl methylcellulose and using the high-viscosity sample injector for data collection at the SACLA beamline. An outward-facing structure of CmABCB1 at a maximum resolution of 2.22 Å is reported, determined by SFX experiments with crystals formed in the lipidic cubic phase (LCP-SFX), which has never been applied to ABC transporters. In the type I crystal, CmABCB1 dimers interact with adjacent molecules via not only the nucleotide-binding domains but also the transmembrane domains (TMDs); such an interaction was not observed in the previous type II crystal. Although most parts of the structure are similar to those in the previous type II structure, the substrate-exit region of the TMD adopts a different configuration in the type I structure. This difference between the two types of structures reflects the flexibility of the substrate-exit region of CmABCB1, which might be essential for the smooth release of various substrates from the transporter.

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Nakane, Takanori, Shinya Hanashima, Mamoru Suzuki, Haruka Saiki, Taichi Hayashi, Keisuke Kakinouchi, Shigeru Sugiyama i in. "Membrane protein structure determination by SAD, SIR, or SIRAS phasing in serial femtosecond crystallography using an iododetergent". Proceedings of the National Academy of Sciences 113, nr 46 (31.10.2016): 13039–44. http://dx.doi.org/10.1073/pnas.1602531113.

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The 3D structure determination of biological macromolecules by X-ray crystallography suffers from a phase problem: to perform Fourier transformation to calculate real space density maps, both intensities and phases of structure factors are necessary; however, measured diffraction patterns give only intensities. Although serial femtosecond crystallography (SFX) using X-ray free electron lasers (XFELs) has been steadily developed since 2009, experimental phasing still remains challenging. Here, using 7.0-keV (1.771 Å) X-ray pulses from the SPring-8 Angstrom Compact Free Electron Laser (SACLA), iodine single-wavelength anomalous diffraction (SAD), single isomorphous replacement (SIR), and single isomorphous replacement with anomalous scattering (SIRAS) phasing were performed in an SFX regime for a model membrane protein bacteriorhodopsin (bR). The crystals grown in bicelles were derivatized with an iodine-labeled detergent heavy-atom additive 13a (HAD13a), which contains the magic triangle, I3C head group with three iodine atoms. The alkyl tail was essential for binding of the detergent to the surface of bR. Strong anomalous and isomorphous difference signals from HAD13a enabled successful phasing using reflections up to 2.1-Å resolution from only 3,000 and 4,000 indexed images from native and derivative crystals, respectively. When more images were merged, structure solution was possible with data truncated at 3.3-Å resolution, which is the lowest resolution among the reported cases of SFX phasing. Moreover, preliminary SFX experiment showed that HAD13a successfully derivatized the G protein-coupled A2a adenosine receptor crystallized in lipidic cubic phases. These results pave the way for de novo structure determination of membrane proteins, which often diffract poorly, even with the brightest XFEL beams.

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Takagishi, Isao, Akira Yamagishi, Hiromitsu Nakazawa, Shingo Sakai, Shintaro Inoue i Satoru Kato. "2P282 Study on the Packing Structure of the Stratum Corneum Lipid Model by Electron Diffraction(40. Membrane structure,Poster Session,Abstract,Meeting Program of EABS & BSJ 2006)". Seibutsu Butsuri 46, supplement2 (2006): S366. http://dx.doi.org/10.2142/biophys.46.s366_2.

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García-Jaramillo, Manuel, Kelli A. Lytle, Melinda H. Spooner i Donald B. Jump. "A Lipidomic Analysis of Docosahexaenoic Acid (22:6, ω3) Mediated Attenuation of Western Diet Induced Nonalcoholic Steatohepatitis in Male Ldlr -/- Mice". Metabolites 9, nr 11 (28.10.2019): 252. http://dx.doi.org/10.3390/metabo9110252.

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Nonalcoholic fatty liver disease (NAFLD) is a major public health problem worldwide. NAFLD ranges in severity from benign steatosis to nonalcoholic steatohepatitis (NASH), cirrhosis, and primary hepatocellular cancer (HCC). Obesity and type 2 diabetes mellitus (T2DM) are strongly associated with NAFLD, and the western diet (WD) is a major contributor to the onset and progression of these chronic diseases. Our aim was to use a lipidomic approach to identify potential lipid mediators of diet-induced NASH. We previously used a preclinical mouse (low density lipoprotein receptor null mouse, Ldlr -/-) model to assess transcriptomic mechanisms linked to WD-induced NASH and docosahexaenoic acid (DHA, 22:6, ω3)-mediated remission of NASH. This report used livers from the previous study to carry out ultra-high-performance liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) and high-performance liquid chromatography coupled with dynamic multi-reaction monitoring (HPLC-dMRM) to assess the impact of the WD and DHA on hepatic membrane lipid and oxylipin composition, respectively. Feeding mice the WD increased hepatic saturated and monounsaturated fatty acids and arachidonic acid (ARA, 20:4, ω6) in membrane lipids and suppressed ω3 polyunsaturated fatty acids (PUFA) in membrane lipids and ω3 PUFA-derived anti-inflammatory oxylipins. Supplementing the WD with DHA lowered hepatic ARA in membrane lipids and ARA-derived oxylipins and significantly increased hepatic DHA and its metabolites in membrane lipids, as well as C20–22 ω3 PUFA-derived oxylipins. NASH markers of inflammation and fibrosis were inversely associated with hepatic C20–22 ω3 PUFA-derived Cyp2C- and Cyp2J-generated anti-inflammatory oxylipins (false discovery rate adjusted p-value; q ≤ 0.026). Our findings suggest that dietary DHA promoted partial remission of WD-induced NASH, at least in part, by lowering hepatic pro-inflammatory oxylipins derived from ARA and increasing hepatic anti-inflammatory oxylipins derived from C20–22 ω3 PUFA.

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Sánchez-Sánchez, Laura, Roberto Fernández, Maria Dolores Ganfornina, Egoitz Astigarraga i Gabriel Barreda-Gómez. "Protective Actions of α-Tocopherol on Cell Membrane Lipids of Paraquat-Stressed Human Astrocytes Using Microarray Technology, MALDI-MS and Lipidomic Analysis". Antioxidants 11, nr 12 (10.12.2022): 2440. http://dx.doi.org/10.3390/antiox11122440.

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Cellular senescence is one of the main contributors to some neurodegenerative disorders. The early detection of senescent cells or their related effects is a key aspect in treating disease progression. In this functional deterioration, oxidative stress and lipid peroxidation play an important role. Endogenous antioxidant compounds, such as α-tocopherol (vitamin E), can mitigate these undesirable effects, particularly lipid peroxidation, by blocking the reaction between free radicals and unsaturated fatty acid. While the antioxidant actions of α-tocopherol have been studied in various systems, monitoring the specific effects on cell membrane lipids at scales compatible with large screenings has not yet been accomplished. Understanding the changes responsible for this protection against one of the consequences of senescence is therefore necessary. Thus, the goal of this study was to determinate the changes in the lipid environment of a Paraquat-treated human astrocytic cell line, as a cellular oxidative stress model, and the specific actions of the antioxidant, α-tocopherol, using cell membrane microarray technology, MALDI-MS and lipidomic analysis. The stress induced by Paraquat exposure significantly decreased cell viability and triggered membrane lipid changes, such as an increase in certain species of ceramides that are lipid mediators of apoptotic pathways. The pre-treatment of cells with α-tocopherol mitigated these effects, enhancing cell viability and modulating the lipid profile in Paraquat-treated astrocytes. These results demonstrate the lipid modulation effects of α-tocopherol against Paraquat-promoted oxidative stress and validate a novel analytical high-throughput method combining cell cultures, microarray technology, MALDI-MS and multivariate analysis to study antioxidant compounds against cellular senescence.

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Losada-Barreiro, Sonia, Fátima Paiva-Martins i Carlos Bravo-Díaz. "Partitioning of Antioxidants in Edible Oil–Water Binary Systems and in Oil-in-Water Emulsions". Antioxidants 12, nr 4 (28.03.2023): 828. http://dx.doi.org/10.3390/antiox12040828.

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In recent years, partitioning of antioxidants in oil–water two-phase systems has received great interest because of their potential in the downstream processing of biomolecules, their benefits in health, and because partition constant values between water and model organic solvents are closely related to important biological and pharmaceutical properties such as bioavailability, passive transport, membrane permeability, and metabolism. Partitioning is also of general interest in the oil industry. Edible oils such as olive oil contain a variety of bioactive components that, depending on their partition constants, end up in an aqueous phase when extracted from olive fruits. Frequently, waste waters are subsequently discarded, but their recovery would allow for obtaining extracts with antioxidant and/or biological activities, adding commercial value to the wastes and, at the same time, would allow for minimizing environmental risks. Thus, given the importance of partitioning antioxidants, in this manuscript, we review the background theory necessary to derive the relevant equations necessary to describe, quantitatively, the partitioning of antioxidants (and, in general, other drugs) and the common methods for determining their partition constants in both binary (PWOIL) and multiphasic systems composed with edible oils. We also include some discussion on the usefulness (or not) of extrapolating the widely employed octanol–water partition constant (PWOCT) values to predict PWOIL values as well as on the effects of acidity and temperature on their distributions. Finally, there is a brief section discussing the importance of partitioning in lipidic oil-in-water emulsions, where two partition constants, that between the oil-interfacial, POI, and that between aqueous-interfacial, PwI, regions, which are needed to describe the partitioning of antioxidants, and whose values cannot be predicted from the PWOIL or the PWOCT ones.

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Santana-Filho, Arquimedes Paixão, Aramís José Pereira, Letícia Adejani Laibida, Normanda Souza-Melo, Wanderson Duarte DaRocha i Guilherme Lanzi Sassaki. "Lipidomic Analysis Reveals Branched-Chain and Cyclic Fatty Acids from Angomonas deanei Grown under Different Nutritional and Physiological Conditions". Molecules 29, nr 14 (17.07.2024): 3352. http://dx.doi.org/10.3390/molecules29143352.

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Angomonas deanei belongs to Trypanosomatidae family, a family of parasites that only infect insects. It hosts a bacterial endosymbiont in a mutualistic relationship, constituting an excellent model for studying organelle origin and cellular evolution. A lipidomic approach, which allows for a comprehensive analysis of all lipids in a biological system (lipidome), is a useful tool for identifying and measuring different expression patterns of lipid classes. The present study applied GC-MS and NMR techniques, coupled with principal component analysis (PCA), in order to perform a comparative lipidomic study of wild and aposymbiotic A. deanei grown in the presence or absence of FBS. Unusual contents of branched-chain iso C17:0 and C19:0-cis-9,10 and-11,12 fatty acids were identified in A. deanei cultures, and it was interesting to note that their content slightly decreased at the log phase culture, indicating that in the latter growth stages the cell must promote the remodeling of lipid synthesis in order to maintain the fluidity of the membrane. The combination of analytical techniques used in this work allowed for the detection and characterization of lipids and relevant contributors in a variety of A. deanei growth conditions.

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Garikapati, Vannuruswamy, Claudia Colasante, Eveline Baumgart-Vogt i Bernhard Spengler. "Sequential lipidomic, metabolomic, and proteomic analyses of serum, liver, and heart tissue specimens from peroxisomal biogenesis factor 11α knockout mice". Analytical and Bioanalytical Chemistry 414, nr 6 (27.01.2022): 2235–50. http://dx.doi.org/10.1007/s00216-021-03860-0.

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AbstractPeroxisomes are versatile single membrane-enclosed cytoplasmic organelles, involved in reactive oxygen species (ROS) and lipid metabolism and diverse other metabolic processes. Peroxisomal disorders result from mutations in Pex genes-encoded proteins named peroxins (PEX proteins) and single peroxisomal enzyme deficiencies. The PEX11 protein family (α, β, and γ isoforms) plays an important role in peroxisomal proliferation and fission. However, their specific functions and the metabolic impact caused by their deficiencies have not been precisely characterized. To understand the systemic molecular alterations caused by peroxisomal defects, here we utilized untreated peroxisomal biogenesis factor 11α knockout (Pex11α KO) mouse model and performed serial relative-quantitative lipidomic, metabolomic, and proteomic analyses of serum, liver, and heart tissue homogenates. We demonstrated significant specific changes in the abundances of multiple lipid species, polar metabolites, and proteins and dysregulated metabolic pathways in distinct biological specimens of the Pex11α KO adult mice in comparison to the wild type (WT) controls. Overall, the present study reports comprehensive semi-quantitative molecular omics information of the Pex11α KO mice, which might serve in the future as a reference for a better understanding of the roles of Pex11α and underlying pathophysiological mechanisms of peroxisomal biogenesis disorders. Graphical abstract

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Zheng, Ping, Mengqian Shen, Ruoyu Liu, Xinkai Cai, Jinting Lin, Lulu Wang, Yu Chen, Guangwei Chen, Shijiang Cao i Yuan Qin. "Revealing Further Insights into Astringent Seeds of Chinese Fir by Integrated Metabolomic and Lipidomic Analyses". International Journal of Molecular Sciences 24, nr 20 (12.10.2023): 15103. http://dx.doi.org/10.3390/ijms242015103.

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Chinese fir (Cunninghamia lanceolata (Lamb.) Hook.) stands as one of the pivotal afforestation tree species and timber resources in southern China. Nevertheless, the occurrence of seed abortion and a notably high proportion of astringent seeds significantly curtail the yield and quality of elite seeds, resulting in substantial economic losses. The development of astringent seeds is accompanied by significant physiological and biochemical alterations. Here, the first combined lipidomic and metabolomic analysis was performed to gain a comprehensive understanding of astringent seed traits. A total of 744 metabolites and 616 lipids were detected, of which 489 differential metabolites and 101 differential lipids were identified. In astringent seeds, most flavonoids and tannins, as well as proline and γ-aminobutyric acid, were more accumulated, along with a notable decrease in lipid unsaturation, indicating oxidative stress in the cells of astringent seeds. Conversely, numerous elemental metabolites were less accumulated, including amino acids and their derivatives, saccharides and alcohols, organic acids and nucleotides and their derivatives. Meanwhile, most lipid subclasses, mainly associated with energy storage (triglyceride and diglyceride) and cell membrane composition (phosphatidic acid, phosphatidylcholine, phosphatidylethanolamine), also exhibited significant reductions. These results reflected a disruption in the cellular system or the occurrence of cell death, causing a reduction in viable cells within astringent seeds. Furthermore, only one lipid subclass, sphingosine phosphate (SoP), was more accumulated in astringent seeds. Additionally, lower accumulation of indole-3-acetic acid and more accumulation of salicylic acid (SA) were also identified in astringent seeds. Both SA and SoP were closely associated with the promotion of programmed cell death in astringent seeds. Collectively, our study revealed significant abnormal changes in phytohormones, lipids and various metabolites in astringent seeds, allowing us to propose a model for the development of astringent seeds in Chinese fir based on existing research and our findings. This work enriches our comprehension of astringent seeds and presents valuable bioindicators for the identification of astringent seeds.

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