Membranes exhibit thermal fluctuations, but transmembrane protein activity breaks the fluctuation-dissipation theorem leading to out-of-equilibrium fluctuations. Active fluctuations have been widely described theoretically [1], but to a lesser extent experimentally.
We will present our recent results on the investigation of out-of-equilibrium fluctuations of phospholipid membranes induced by...
Deuteration is a useful strategy to modulate the visibility of specific components of the sample using neutron scattering techniques as it offers increased contrast with no significant impact on the physico-chemistry of the membrane. In this context, mass production of biologically relevant deuterated phospholipids of varying head groups and acyl chain compositions is currently the limiting...
Mixtures of the phospholipid 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) and the saponin beta-aescin spontaneously form monodisperse, bilayered discoidal micelles (also known as "bicelles" or "nanodisks") in aqueous solution. Such bicelles form below the melting temperature of DMPC when the phospholipids are in the rigid state and are precursors of spontaneously formed vesicles. The...
We are presenting transmission electron microscopy (TEM) imaging as an advanced tool for characterization freestanding crystalline metalorganic networks (MONs) [1]. As an example of creation of ultrathin material, the two-dimensional (2D) layer of the monomolecular thickness amphiphilic derivatives of calix[4]arenes are selected [1, 2]. The methyl-carboxy-functionalized calix[4]arenes can...
The cell membrane is a universal component found in both prokaryotic and eukaryotic cells, which is composed mainly of a series of lipid mixtures that act as a physical barrier against various pathogens, in addition to other functions that remain unknown. There is a large difference in the lipid composition of bacterial and mammalians cytoplasmic membranes, a fact that can be used to obtain...
Lipids are found widely in biological systems because of their unique interfacial properties. They are the primary component of cell membranes, which act as barriers containing the contents of the cells and protecting them from external threats. In fulfilling their function, the lipid membranes are exposed to oxidation processes that change their molecular structure. Such processes occur...
The current tree of life is divided into three domains: Bacteria, Eukarya and Archaea. While bacterial and eukaryotic lipids are constituted of sn-3 glycerol on which straight fatty acids are ester-bound, archaeal lipids contain ramified isoprenoid hydrocarbons that are linked through ether bounds on a sn-1 glycerol. As a results, plasma membranes are spatially organized into domains of...
Fundamental understanding of the solubilisation process in self-assembly systems is important for many applications including membrane solubilization and protein extraction. The kinetic processes involved in mixtures of surfactants and block copolymer micelles are not well understood. However, it is commonly known that surfactants exhibit rather fast equilibration kinetics, in the order of...
Antimicrobial peptides (AMPs) are found in nature to selectively kill microbes by disrupting their cell membranes. Because of the rapid physical action, pathogens are less likely to develop the relative resistance mechanism to the AMPs. Therefore, AMPs are the potential candidates for the multiple-drug resistance (MDR) treatments. We have designed a series of surfactant-like AMPs based on the...
In humans, dihydroorotate dehydrogenase (DHODH) is an flavoprotein found in the inner mitochondrial membrane (IMM). DHODH catalyzes the oxidation of dihydroorotic acid with the concomitant reduction of ubiquinone Q10 (coenzyme Q10), thus acting as a link between the de novo pyrimidine biosynthesis and the mitochondrial respiratory chain. DHODH is a well validated target for immunosuppressive...
A central event in pathogenesis of Alzhaimer’s diseases are thought to be intracellular and extracellular accumulation, aggregation and misfolding of low molecular mass peptides such as β-amyloid (Aβ1-42), tau protein (Tau) and s100A9 [1,2, 6]. Small size aggregates-oligomers were found to be extremely neurotoxic in vitro and in vivo with the ability to disrupt the major neuron membranes...
Using elementary building blocks to mimic and reconstruct biological structures is intriguing both from fundamental aspects, providing a simple model to study a complex environment, as well as from the applicative point of view, opening the possibility of utilizing such constructs for the creation of new functional materials. Understanding the key parameters governing the interaction between...
Surfactant N,N-dimethyl-1-dodecanamine-N-oxide (DDAO) possess a wide range of biological effects (antimicrobial, phytotoxic, antiphotosynthetic, immunomodulatory). Interaction of non-ionic form of DDAO with DOPC and DOPC-CHOL (CHOL:DOPC =0.5:1 mol/mol) model membranes was studied by SANS. Unilamellar liposomes were prepared by extrusion in PBS buffer. Aggregation of DOPC and DOPC-CHOL...
Due to alarming increase in the number of cases of antibiotic-resistant bacterial infections, it is necessary to develop new antibiotics, explore relationships between structure and observed effect and study the mechanism of antimicrobial action. Amphipathic antimicrobial peptides are perspective compounds which display antimicrobial effects. Dermaseptins represent a large group of cationic...
Membrane protein solubilization implies the use of amphipathic detergents that form protective belts around hydrophobic patches to maintain the protein’s structural integrity outside of the lipid environment. Consequently, the resulting SANS signal includes both protein and detergent belt signatures leading to a global outer shell larger than the envelope expected for the protein alone;...
The location of n-decane molecules within the model biological membrane consisting of dioleoyl-phosphocholine (DOPC) bilayers has been investigated via small angle neutron diffraction (SAND) method. Diffraction patterns of the samples containing varied amounts of labeled and unlabeled n-decane have been obtained at various H2O:D2O scattering contrasts and utilized in the reconstruction of...
Metallacarboranes are a unique class of inorganic polyhedral clusters containing carbon, boron, hydrogen, and metal atoms. A typical metallacarborane is the nanometric size anion [COSAN]-: a Co3+ metal ion sandwiched between two [C2B9H11]2− (dicarbollide) clusters. In the last ten years we have shown that COSAN and its derivatives have all the properties of classical surfactants (surface...
Cationic lipids are widely used in modern drug delivery systems such as lipid nano-particles (LNPs). These drug carriers are multi-component systems (containing novel cationic lipids, cholesterol, phospholipids, siRNA/mRNA) with strognly pH-dependent structures, which are poorly characterized. Earlier experimental methods could provide the information about optimal sizes of LNPs, but their...
Lipid bilayers are self-assembling structures constituting the membranes of every animal cell and many others cell-derived nanoparticles like Extracellular vesicles (EVs). EVs are vesicles with dimensions ranging from 50 to 500nm produced and released by cells to act as cargoes for biological material (proteins, nucleic acids) which play a pivotal role in intercellular communication and in...
Developments in the field of X-ray diffraction, such as XFEL (X-ray Free Electron Laser) has become advantageous in studying Membrane Protein’s structure and dynamics. For in-vitro studies, membrane protein needs to be reconstituted in a more native like hydrophobic environment. A novel membrane model system, Nanodisc due to its defined size and low mass-ratio of lipid to protein, proves to...
The study of active membrane proteins requires an environment which is as close as possible to their natural environment to retain protein function, while at the same time keeping the system as simple as possible to allow for an experimental characterization and to be able to identify factors which influence the system. Tethered lipid bilayers (tBLMs) represent an experimentally accessible and...
Deuteration is a useful strategy to modulate the visibility of specific components of the sample using neutron scattering techniques as it offers increased contrast with no significant impact on the physico-chemistry of the membrane. In this context, mass production of biologically relevant deuterated phospholipids of varying head groups and acyl chain compositions is currently the limiting...
PolyElectrolyte-Surfactant Complexes (PESCs) are interesting colloidal systems characterized by a complex, mesoscopically ordered inter- and intra-particle structure. Depending on their composition such assemblies are often sensitive to environmental stimuli, e.g. T and pH. One building block of such a potentially functional material can be the naturally derived polycation chitosan and the...
Supported lipid bilayers (SLBs) are often used for investigation in biophysics. They can be a good model system because it is not difficult to compose them at different scales of complexity. In fact, by using mixtures of lipids, or the addition of other proteins, the interactions between those bilayer components can be investigated. Alternatively, polymers can be attached to a defined...
Phosphate starvation is a frequent nutrient stress encountered by plants to which they adapt by exerting different mechanisms. The partial degradation of phospholipids, a common constituent of cellular membranes, is a widespread response observed in plants to increase the intracellular phosphate availability. To maintain membrane integrity, the degraded phospholipids have to be replaced by a...
Polymers with balanced hydrophilicity can translocate through biological membranes without doing damage. In the case of synthetic polymers there are only few reports of translocation using charged polymers [1-2]. For non-charged polymers translocation phenomena were predicted theoretically [3] but not verified experimentally.
We have synthesized such balanced, alternating...
It has been known for a long time that adsorbed bilayers of n-alkyl trimethylammonium bromide surfactants, CnTAB, at aqueous solution/hydrophilic solid interfaces are thin, much less than two extended hydrocarbon chains. These materials are bactericidal but the mechanism is not well-understood although differences in behaviour with chain length are established. For these reasons...
Histatin 5 (Hst5) is a histidine-rich, 24 amino acid protein, classified as an intrinsically disordered protein (IDP). It is a cationic salivary protein found to play a crucial role in fungicidal activity, and its activity to inhibit the growth and viability of Candida albicans has been evaluated using a variety of techniques. The underlying mechanism is however not very well known. The aim of...
Pulmonary surfactant consists on an adsorbed phospholipid-based monolayer at the alveolar air-liquid interface connected to a membrane reservoir placed in the aqueous subphase. Its main function is to minimize the surface tension stabilizing the mammalian respiratory surface, enabling breathing dynamics and preventing alveolar collapse during expiration. Pulmonary surfactant is mainly composed...
