scholarly journals The Structural Integrity of the Model Lipid Membrane during Induced Lipid Peroxidation: The Role of Flavonols in the Inhibition of Lipid Peroxidation

Antioxidants ◽  
2020 ◽  
Vol 9 (5) ◽  
pp. 430 ◽  
Author(s):  
Anja Sadžak ◽  
Janez Mravljak ◽  
Nadica Maltar-Strmečki ◽  
Zoran Arsov ◽  
Goran Baranović ◽  
...  
Keyword(s):  
Lipid Peroxidation ◽  
Lipid Bilayers ◽  
Lipid Membranes ◽  
Structural Changes ◽  
Structural Integrity ◽  
Lipid Membrane ◽  
Membrane Properties ◽  
Structural Reorganization ◽  
Unsaturated Lipids ◽  
Oxidative Attack

The structural integrity, elasticity, and fluidity of lipid membranes are critical for cellular activities such as communication between cells, exocytosis, and endocytosis. Unsaturated lipids, the main components of biological membranes, are particularly susceptible to the oxidative attack of reactive oxygen species. The peroxidation of unsaturated lipids, in our case 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC), induces the structural reorganization of the membrane. We have employed a multi-technique approach to analyze typical properties of lipid bilayers, i.e., roughness, thickness, elasticity, and fluidity. We compared the alteration of the membrane properties upon initiated lipid peroxidation and examined the ability of flavonols, namely quercetin (QUE), myricetin (MCE), and myricitrin (MCI) at different molar fractions, to inhibit this change. Using Mass Spectrometry (MS) and Fourier Transform Infrared Spectroscopy (FTIR), we identified various carbonyl products and examined the extent of the reaction. From Atomic Force Microscopy (AFM), Force Spectroscopy (FS), Small Angle X-Ray Scattering (SAXS), and Electron Paramagnetic Resonance (EPR) experiments, we concluded that the membranes with inserted flavonols exhibit resistance against the structural changes induced by the oxidative attack, which is a finding with multiple biological implications. Our approach reveals the interplay between the flavonol molecular structure and the crucial membrane properties under oxidative attack and provides insight into the pathophysiology of cellular oxidative injury.

Selective arrangement of vesicles on artificial lipid membrane by biotin-avidin interaction

2021 ◽  
Author(s):  
Kai Hashino ◽  
Daiya Mombayashi ◽  
Yuto Nakatani ◽  
Azusa Oshima ◽  
Masumi Yamaguchi ◽  
...  
Keyword(s):  
Lipid Bilayer ◽  
Lipid Bilayers ◽  
Liquid Crystalline ◽  
Lipid Membrane ◽  
Unsaturated Lipid ◽  
Si Substrates ◽  
Phase Domain ◽  
Unsaturated Lipids ◽  
Lipid Mixtures ◽  
The Difference

Abstract Lipid bilayers suspended over microwells on Si substrates are promising platforms for nanobiodevices that mimic cell membranes. Using the biotin-avidin interaction, we have succeeded in selectively arranging vesicles on the freestanding region of a lipid bilayer. When ternary lipid mixtures of saturated lipid, unsaturated lipid, and cholesterol are used, they separate into liquid-order (Lo) and liquid-crystalline (Lα) domains. A freestanding lipid bilayer prefers the Lα-phase over the Lo-phase because of the difference in their flexibility. In addition, the type of biotinylated lipid determines whether it is localized in the Lα-phase domain or the Lo-phase domain. As a result, the biotinylated unsaturated lipids localized in the Lα-phase domain aggregate in the freestanding lipid bilayer, and vesicles labeled with biotin selectively bind to the freestanding lipid bilayer by the biotin-avidin interaction. This technique helps to introduce biomolecules into the freestanding lipid bilayer of nanobiodevices via vesicles.

scholarly journals AFM nanoindentation reveals decrease of elastic modulus of lipid bilayers near freezing point of water

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Calum Gabbutt ◽  
Wuyi Shen ◽  
Jacob Seifert ◽  
Sonia Contera
Keyword(s):  
Lipid Bilayers ◽  
Lipid Membranes ◽  
Structural Changes ◽  
Freezing Point ◽  
Liquid Environment ◽  
Force Microscopy ◽  
Atomic Force ◽  
Afm Imaging ◽  
Underlying Causes ◽  
Irreversible Injury

AbstractCell lipid membranes are the primary site of irreversible injury during freezing/thawing and cryopreservation of cells, but the underlying causes remain unknown. Here, we probe the effect of cooling from 20 °C to 0 °C on the structure and mechanical properties of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) bilayers using atomic force microscopy (AFM) imaging and AFM-based nanoindentation in a liquid environment. The Young’s modulus of elasticity (E) at each temperature for DPPC was obtained at different ionic strengths. Both at 20 mM and 150 mM NaCl, E of DPPC bilayers increases exponentially –as expected–as the temperature is lowered between 20 °C and 5 °C, but at 0 °C E drops from the values measured at 5 °C. Our results support the hypothesis that mechanical weakening of the bilayer at 0 °C  is produced by  structural changes at the lipid-fluid interface.

scholarly journals Characterization of Lipid Membrane Properties for Tunable Electroporation

2012 ◽  
Author(s):  
H. Jeremy Cho ◽  
Shalabh C. Maroo ◽  
Evelyn N. Wang
Keyword(s):  
Lipid Bilayers ◽  
Lipid Membrane ◽  
Contact Angle Measurement ◽  
Angle Measurement ◽  
Membrane Properties ◽  
Force Microscopy ◽  
Packing Structure ◽  
Atomic Force ◽  
Dynamics Simulations

Lipid bilayers form nanopores on the application of an electric field. This process of electroporation can be utilized in different applications ranging from targeted drug delivery in cells to nano-gating membrane for engineering applications. However, the ease of electroporation is dependent on the surface energy of the lipid layers and thus directly related to the packing structure of the lipid molecules. 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) lipid monolayers were deposited on a mica substrate using the Langmuir-Blodgett (LB) technique at different packing densities and analyzed using atomic force microscopy (AFM). The wetting behavior of these monolayers was investigated by contact angle measurement and molecular dynamics simulations. It was found that an equilibrium packing density of liquid-condensed (LC) phase DPPC likely exists and that water molecules can penetrate the monolayer displacing the lipid molecules. The surface tension of the monolayer in air and water was obtained along with its breakthrough force.

scholarly journals Theoretical and computational modeling of peptide-lipid bilayer interaction studied by dynamic force spectroscopy

2019 ◽  
Author(s):  
◽  
Milica Utjesanovic
Keyword(s):  
Computational Modeling ◽  
Lipid Bilayer ◽  
Lipid Bilayers ◽  
Lipid Membranes ◽  
Lipid Membrane ◽  
Conformational Dynamics ◽  
Quantitative Description ◽  
Md Simulations ◽  
Dynamic Force ◽  
Detachment Rate

This thesis consists of three interrelated theoretical and computational modeling projects that investigate different aspects of peptide-lipid membrane interactions. (1) A general theoretical approach is formulated for the quantitative description of the detachment force distribution, P(F), and the corresponding force dependent detachment rate, k(F), of a peptide from a lipid bilayer, by assuming that peptide detachment from lipid membranes occurs stochastically along a few dominant diffusive pathways. Besides providing a consistent interpretation of the experimental data, the new method also predicts that k(F) exhibits catch-bond behavior (when, counter intuitively, the detachment rate decreases with increasing force). (2) The proposed multiple detachment pathways method is tested and validated for a particular peptide (SecA2-11) interacting with both zwitterionic POPC lipid and polar E. Coli membranes. Furthermore, molecular dynamics (MD) simulations are used to explored the conformational dynamics of SecA2-11 during its interaction with both POPC and anionic POPG lipid bilayers. (3) Finally, MD simulations are used to explore the conformational dynamics and energetics of the peptide melittin (MWT) and its diastereomer (MD4) interacting with POPC and POPG lipid bilayers. The obtained results provide further insight into the role of secondary structure in peptide-lipid bilayer interactions.

scholarly journals Correlative microscopy reveals the nanoscale morphology of E. coli-derived supported lipid bilayers

2021 ◽  
Author(s):  
Karan Bali ◽  
Zeinab Mohamed ◽  
Anna-Maria Pappa ◽  
Susan Daniel ◽  
Clemens F. Kaminski ◽  
...  
Keyword(s):  
Lipid Bilayers ◽  
Lipid Membrane ◽  
Lipid Vesicles ◽  
Outer Membrane Vesicles ◽  
Atomic Scale ◽  
Membrane Properties ◽  
Supported Lipid Bilayers ◽  
Structured Illumination ◽  
Structured Illumination Microscopy ◽  
Natural And Synthetic

Supported lipid bilayers (SLBs) made from reconstituted lipid vesicles are an important tool in molecular biology. A breakthrough in the field has come with the use of vesicles derived from cell membranes to form SLBs. These new supported bilayers, consisting both of natural and synthetic components, provide a physiologically relevant system on which to study protein-protein interactions as well as protein-ligand interactions and other lipid membrane properties. These complex bilayer systems hold promise but have not yet been fully characterised in terms of their composition, ratio of natural to synthetic component and membrane protein content. Here, we describe a method of correlative atomic force (AFM) with structured illumination microscopy (SIM) for the accurate mapping of complex lipid bilayers that consist of a synthetic fraction and a fraction of lipids derived from Escherichia coli outer membrane vesicles (OMVs). We exploit the enhanced resolution and molecular specificity that SIM can offer to identify areas of interest in these bilayers and the atomic scale resolution that the AFM provides to create detailed topography maps of the bilayers. We are thus able to understand the way in which the two different lipid fractions (natural and synthetic) mix within the bilayers, quantify the amount of bacterial membrane incorporated in the bilayer and directly visualise the interaction of these bilayers with bacteria-specific, membrane-binding proteins. Our work sets the foundation for accurately understanding the composition and properties of OMV-derived SLBs and establishes correlative AFM/ SIM as a method for characterising complex systems at the nanoscale.

A model for the study of the mechanism of a low pH-induced interaction of the virus fusion proteins and cell membranes

1991 ◽  
Vol 11 (3) ◽  
pp. 131-137 ◽  
Author(s):  
S. E. Glushakova ◽  
A. L. Ksenofontov ◽  
N. V. Fedorova ◽  
L. A. Mazhul ◽  
O. N. Ageeva ◽  
...  
Keyword(s):  
Amino Acids ◽  
Lipid Membranes ◽  
Fusion Proteins ◽  
Cell Membranes ◽  
Molecular Mechanisms ◽  
Lipid Membrane ◽  
Specific Activity ◽  
Low Ph ◽  
Structural Reorganization ◽  
First Results

A model is proposed for the study of molecular mechanisms of a low pH-induced interaction of fusion proteins of enveloped viruses and cell membranes. The model consists of large monolamellar liposomes containing ionophore nigericin in their membranes and ectodomains of fusion protein in their inner space. The process of interaction of the protein with the lipid bilayer is triggered by acidification of the liposomal constituents to the pH of fusion with the help of nigericin by adding citric acid to the outer medium. To visualize the protein structural reorganization, the tritium planigraphy was used.Comparison of the values of specific labelling of the proteins and distribution of radioactivity in individual amino acids in control (at neutral pH) and experimental liposome samples (at the pH of fusion) permits to realise the character of protein-membrane interaction. We have obtained the first results in the study of interaction of the bromelain-released soluble ectodomain of the HAXX molecule (BHA)—with the lipid membrane. The observed increase in the protein specific activity and selective increase in the specific activity of hydrophobic amino acids Ile, Phe and Tyr in experimental liposome samples as compared with the controls did not contradict to the conventional concept, that a hydrophobic N-terminus of HA2 subunit of hemagglutinin is responsible for its interaction with lipid membranes.

scholarly journals Adhesion and Structural Changes of PEGylated Lipid Nanocarriers on Silica Surfaces

Physchem ◽  
2021 ◽  
Vol 1 (2) ◽  
pp. 133-151
Author(s):  
Philipp Grad ◽  
Katarina Edwards ◽  
Víctor Agmo Hernández
Keyword(s):  
Lipid Bilayers ◽  
Structural Changes ◽  
Lipid Membrane ◽  
Complete Separation ◽  
Supported Lipid Bilayers ◽  
Pegylated Liposomes ◽  
Silica Surfaces ◽  
Lipid Nanocarriers ◽  
Liquid Ordered ◽  
Pegylated Lipids

PEGylated lipid nanoparticles have a continuously expanding range of applications, particularly within pharmaceutical areas. Hereby, it is shown with the help of the Quartz Crystal Microbalance with Dissipation monitoring (QCM-D) and other surface sensitive techniques that, at room temperature, PEGylated liposomes and lipodisks adhere strongly to silica surfaces resulting in the displacement of the hydration layer of silica and the formation of immobilized nanoparticle films. Furthermore, it is shown that drastic changes in the structure of the immobilized films occur if the temperature is increased to >35 °C. Thus, intact immobilized PEGylated liposomes rupture and spread, even in the gel phase state; immobilized lipodisks undergo complete separation of their components (bilayer forming lipids and PEGylated lipids) resulting in a monolayer of adsorbed PEGylated lipids; and PEGylated supported lipid bilayers release part of the water trapped between the lipid membrane and the surface. It is hypothesized that these changes occur mainly due to the changes in the configuration of PEG chains and a drastic decrease of the affinity of the polymer for water. The observed phenomena can be applied, e.g., for the production of defect-free supported lipid bilayers in the gel or liquid ordered phase states.

scholarly journals Mimicking the Mammalian Plasma Membrane: An Overview of Lipid Membrane Models for Biophysical Studies

Biomimetics ◽  
2020 ◽  
Vol 6 (1) ◽  
pp. 3
Author(s):  
Alessandra Luchini ◽  
Giuseppe Vitiello
Keyword(s):  
Plasma Membrane ◽  
Lipid Bilayers ◽  
Lipid Membranes ◽  
Cell Membranes ◽  
Lipid Membrane ◽  
Lipid Phase ◽  
Chemical Information ◽  
Lipid Species ◽  
Membrane Models ◽  
The Impact

Cell membranes are very complex biological systems including a large variety of lipids and proteins. Therefore, they are difficult to extract and directly investigate with biophysical methods. For many decades, the characterization of simpler biomimetic lipid membranes, which contain only a few lipid species, provided important physico-chemical information on the most abundant lipid species in cell membranes. These studies described physical and chemical properties that are most likely similar to those of real cell membranes. Indeed, biomimetic lipid membranes can be easily prepared in the lab and are compatible with multiple biophysical techniques. Lipid phase transitions, the bilayer structure, the impact of cholesterol on the structure and dynamics of lipid bilayers, and the selective recognition of target lipids by proteins, peptides, and drugs are all examples of the detailed information about cell membranes obtained by the investigation of biomimetic lipid membranes. This review focuses specifically on the advances that were achieved during the last decade in the field of biomimetic lipid membranes mimicking the mammalian plasma membrane. In particular, we provide a description of the most common types of lipid membrane models used for biophysical characterization, i.e., lipid membranes in solution and on surfaces, as well as recent examples of their applications for the investigation of protein-lipid and drug-lipid interactions. Altogether, promising directions for future developments of biomimetic lipid membranes are the further implementation of natural lipid mixtures for the development of more biologically relevant lipid membranes, as well as the development of sample preparation protocols that enable the incorporation of membrane proteins in the biomimetic lipid membranes.

scholarly journals Proteins and Ions Compete for Membrane Interaction: the case of Lactadherin

2020 ◽  
Author(s):  
A. M. De Lio ◽  
D. Paul ◽  
R. Jain ◽  
J. H. Morrissey ◽  
T. V. Pogorelov
Keyword(s):  
Plasma Membrane ◽  
Blood Coagulation ◽  
Lipid Bilayers ◽  
Species Interactions ◽  
Drug Targets ◽  
Structural Changes ◽  
Lipid Membrane ◽  
Cell Damage ◽  
Experimental Studies ◽  
Coagulation Cascade

ABSTRACTCharged molecular species, such as ions, play a vital role in the life of the cell. In particular, divalent calcium ions (Ca2+) are critical for activating cellular membranes. Interactions between Ca2+ and anionic phosphatidylserine (PS) lipids result in structural changes of the plasma membrane and are vital for many signaling pathways, such as the tightly regulated blood coagulation cascade. Upon cell damage, PS lipids are externalized to the outer leaflet, where they are not only exposed to Ca2+, but also to proteins. Lactadherin is a glycoprotein, important for cell-adhesion, that can act as an anticoagulant. While a number of experimental studies have been performed on lactadherin’s C2 domain’s (LactC2) binding affinity for PS molecules, an atomistic description of LactC2 interactions with PS lipids in the plasma membrane is lacking. We performed extensive all-atom molecular dynamics simulations of mixed lipid bilayers and experimental characterization of LactC2-membrane interactions in the presence and absence of Ca2+ and characterized PS-Ca2+ and PS-LactC2 interactions to guide our understanding of how these interactions initiate and impede blood coagulation, respectively. The captured spontaneously formed long-lived PS-Ca2+ and PS-LactC2 complexes revealed that the protein side chains involved in PS-LactC2 interactions appear to be affected by the presence of Ca2+. The degree of LactC2 insertion into the lipid bilayer also appears to be dependent on the presence of Ca2+. Characterizing the interactions between Ca2+ and LactC2 with PS lipids can lead to a greater understanding of the activation and regulation of the blood coagulation cascade and of the basis of charged species interactions with the lipid membrane.STATEMENT OF SIGNIFICANCELactadherin plays an important role in cellular signaling including blood coagulation. Many of these processes involve lactadherin interacting with the lipids of the cell plasma membrane. Lactadherin acts as an anticoagulant and contributes to a number of health issues. Understanding the interactions that drive lactadherin’s anticoagulant properties can lead to potential new drug targets.

scholarly journals Accumulation of styrene oligomers alters lipid membrane phase order and miscibility

2021 ◽  
Vol 118 (4) ◽  
pp. e2016037118
Author(s):  
Mattia I. Morandi ◽  
Monika Kluzek ◽  
Jean Wolff ◽  
André Schroder ◽  
Fabrice Thalmann ◽  
...  
Keyword(s):  
Phase Behavior ◽  
Lipid Bilayers ◽  
Lipid Membranes ◽  
Lipid Membrane ◽  
Spatial Modulation ◽  
Plastic Materials ◽  
Polymeric Species ◽  
Cell Components ◽  
Membrane Models ◽  
Membrane Mechanical Properties

Growth of plastic waste in the natural environment, and in particular in the oceans, has raised the accumulation of polystyrene and other polymeric species in eukyarotic cells to the level of a credible and systemic threat. Oligomers, the smallest products of polymer degradation or incomplete polymerization reactions, are the first species to leach out of macroscopic or nanoscopic plastic materials. However, the fundamental mechanisms of interaction between oligomers and polymers with the different cell components are yet to be elucidated. Simulations performed on lipid bilayers showed changes in membrane mechanical properties induced by polystyrene, but experimental results performed on cell membranes or on cell membrane models are still missing. We focus here on understanding how embedded styrene oligomers affect the phase behavior of model membranes using a combination of scattering, fluorescence, and calorimetric techniques. Our results show that styrene oligomers disrupt the phase behavior of lipid membranes, modifying the thermodynamics of the transition through a spatial modulation of lipid composition.

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