Phospholipid Mono Research Articles

Addressable Cholesterol Analogs for Live Imaging of Cellular Membranes

Cholesterol is an essential component of most biological membranes and serves important functions in controlling membrane integrity, organization, and signaling. However, probes to follow the dynamic distribution of cholesterol in live cells are scarce and so far show only limited applicability. Herein, we addressed this problem by synthesizing and characterizing a class of versatile and clickable cholesterol-based imidazolium salts. We show that these cholesterol analogs faithfully mimic the biophysical properties of natural cholesterol in phospholipid mono- and bilayers, and that they integrate into the plasma membrane of cultured and primary human cells. The membrane-incorporated cholesterol analogs can be specifically labeled by click chemistry and visualized in live-cell imaging experiments that show a distribution and behavior comparable with that of endogenous membrane cholesterol. These results indicate that the cholesterol analogs can be used to reveal the dynamic distribution of cholesterol in live cells.

Unusual penetration of phospholipid mono- and bilayers by Quillaja bark saponin biosurfactant

The interactions between a model phospholipid 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) and a biosurfactant Quillaja Bark Saponin (QBS) obtained from the bark of Quillaja saponaria Molina were studied using simple models of biological membranes. QBS is known to interact strongly with the latter, exerting a number of haemolytic, cytotoxic and anti-microbial actions. The interaction of QBS dissolved in the subphase with DPPC monolayers and silicon-supported bilayers was studied above the cmc (10−3M). Surface pressure relaxation and surface dilatational rheology combined with quartz crystal microbalance (QCM) and neutron reflectivity (NR) were employed for this purpose. The DPPC-penetrating abilities of QBS are compared with those of typical synthetic surfactants (SDS, CTAB and Triton X-100). We show that the penetration studies using high surface activity (bio)surfactants should be performed by a subphase exchange, not by spreading onto the surfactant solution. In contrast to the synthetic surfactants of similar surface activity, QBS does not collapse DPPC mono- and bilayers, but penetrates them, improving their surface dilatational elastic properties even in the highly compressed solid state. The dilatational viscoelasticity modulus increases from 204 mN/m for pure DPPC up to 310 mN/m for the QBS-penetrated layers, while it drops to near zero values in the case of the synthetic surfactants. The estimated maximum insertion pressure of QBS into DPPC monolayers exceeds the maximum surface pressure achievable in our setup, in agreement with the surface rheological response of the penetrated layers.

Changes in the structure of model biological membranes in the presence of perfluorooctanesulphonic acid – Electrochemical and EC-STM study

The changes caused by the presence of perfluorooctanesulphonic acid (PFOS) in the structure and electrochemical characteristics of model biological membranes composed of 1,2-dimyristoyl- sn-glycero-3-phosphocholine (DMPC) supported on gold electrodes were examined using electrochemical techniques and electrochemical scanning tunneling microscopy. Phospholipid mono and bilayers were prepared using the Langmuir–Blodgett (LB) technique alone or combined with of the Langmuir–Schaefer (LB/LS) techniques. Square wave voltammetry was employed to monitor the incorporation of PFOS into already existing model membranes. The accessibility of potassium ferrocyanides to the electrode surface depended on the time of contact of the bilayer with PFOS solutions. Electrostatic attraction between PFOS present in the model membrane and positively charged probes resulted in the adsorption of the probe on the lipid membrane modified electrode. Even highly soluble species, i.e. hexaamineruthenium complex revealed adsorption on the gold electrodes modified with DMPC bilayers containing PFOS. The presence of PFOS in model biological membranes was visualized by means of electrochemical scanning tunneling microscopy (EC-STM). Topographically higher PFOS-enriched domains were clearly distinguishable among lower pure DMPC regions.

Interactions of Antimicrobial Peptide Latarcin With Model Cell Membrane

Latarcins are linear antimicrobial peptides purified from the venom of the Lachesana tarabaevi spider. They are highly active against Gram-positive and Gram-negative bacteria with minimum inhibitory concentrations (MIC) at the micromolar level and low hemolytic activity (1, 2). In the present work, a 26 residue peptide Latarcin 2a that adopts a helix-hinge-helix conformation in a membrane mimetic environment (1, 2) was studied as well as a derivative obtained by replacing the Guanine 11 by with Alanine. The interaction of the peptides with phospholipid mono and bilayers were investigated using Langmuir-Blodgett monolayer technique, Atomic Force Microscopy (AFM), calcein leakage assay and UV resonance Raman spectroscopy. Effect of small changes in the primary structure of the peptide on the membrane rupturing activity is discussed.

The formation of lipid bilayers on surfaces

The adsorption of biological molecules at solid–liquid interfaces is growing in importance due to its application to a very broad range of fields. Biomimetic systems like phospholipid mono- or bilayers are used to study such adsorption processes in great detail. Here we show how the formation of a complete lipid bilayer by vesicle adsorption and rupture depends on the type of the surface used. Fairly smooth SiO 2 surfaces and much rougher polyelectrolyte cushions are used to study this process. Depending on the chemical structure of the lipids, two different pathways are found on SiO 2 surfaces: either vesicle adsorption occurs in a first step until a critical coverage is reached followed by vesicle rupture and bilayer formation or adsorption and vesicle rupture occur almost at the same time. In the case of polyelectrolyte cushions, both neutron reflectivity and quartz crystal microbalance experiments show that the formation of homogeneous DMPC bilayers is significantly better on the negatively charged PSS surface compared to the positively charged PAH surface.

Interactions of antimicrobial peptide from C-terminus of myotoxin II with phospholipid mono- and bilayers

Comparative studies of the effect of a short synthetic cationic peptide, pEM-2 (KKWRWWLKALAKK), derived from the C-terminus of myotoxin II from the venom of the snake Bothrops asper on phospholipid mono- and bilayers were performed by means of Langmuir Blodgett (LB) monolayer technique, atomic force microscopy and calcein leakage assay. Phospholipid mono- and bilayers composed of single zwitterionic or anionic phospholipids as well as lipid mixtures mimicking bacterial cell membrane were used. LB measurements indicate that the peptide binds to both anionic and zwitterionic phospholipid monolayers at low surface pressure but only to anionic at high surface pressure. Preferential interaction of the peptide with anionic phospholipid monolayer is also supported by a more pronounced change of the monolayer pressure/area isotherms induced by the peptide. AFM imaging reveals the presence of nanoscale aggregates in lipid/peptide mixture monolayers. At the same time, calcein leakage experiment demonstrated that pEM-2 induces stronger disruption of zwitterionic than anionic bilayers. Results of the study indicate that electrostatic interactions play a significant role in the initial recognition and binding of pEM-2 to the cell membrane. However, membrane rupturing activity of the peptide depends on interactions other than simple ionic attraction.

Lipid‐binding role of βII‐spectrin ankyrin‐binding domain

It is known that erythroid and non-erythroid spectrins binding of vesicles and monolayers containing PE proved sensitive to inhibition by red blood cell ankyrin. We now show that the bacterially-expressed recombinant peptides representing betaII(brain)-spectrin's ankyrin-binding domain and its truncated mutants showed lipid-binding activity, although only those containing a full-length amino terminal fragment showed high to moderate affinity towards phospholipid mono- and bilayers and a substantial sensitivity of this binding to inhibition by ankyrin. These results are in accordance with our published data on betaI-spectrin's ankyrin-binding domain [Hryniewicz-Jankowska A, et al. Mapping of ankyrin-sensitive, PE/PC mono- and bilayer binding site in erythroid beta-spectrin. Biochem J 2004;382:677-85]. Moreover, we tested also the effect of transient transfection of living cells of several cell-lines with vectors coding for GFP-conjugates including betaII and also betaI full-length ankyrin-binding domain and their truncated fragments on the membrane skeleton organization. The transfection with constructs encoding full-length ankyrin-binding domain of betaII and betaI spectrin resulted in increased aggregation of membrane skeleton and its punctate appearance in contrast to near normal appearance of membrane skeleton of cells transiently transfected with GFP control or construct encoding ankyrin-binding domain truncated at their N-terminal region. Our results therefore indicate the importance of N-terminal region for lipid-binding activity of the beta-spectrin ankyrin-binding domain and its substantial role in maintaining the spectrin-based skeleton distribution.

Direct Measurement of Chain Order in Single Phospholipid Mono- and Bilayers with Multiplex CARS

We present direct measurements of the thermodynamic state of single phospholipid mono- and bilayers based on the intrinsic vibrational properties of the molecules. The increased, shot-noise limited, sensitivity of multiplex coherent anti-Stokes Raman scattering permits the acquisition of vibrational spectra of single lipid bilayers with a signal-to-noise ratio of 4 in 20 ms. The lipid chain order for both liquid-crystalline and gel phase supported lipid bilayers is determined. Using deuterated lipids, vibrational spectra can be measured selectively in either of the leaflets of an asymmetric bilayer.

Location of a laminin peptide fragment in phospholipid mono and bilayers

The surface properties of a laminin related decapeptide were determined using Langmuir films. Moreover, its interaction with phospholipids was studied using both DPPC mono- and bi-layer liposomes as membrane models. Changes in fluidity of the bilayers induced by this peptide were determined by means of polarizable probes such as 8-anilino-1-naphthalene sulfonic acid (ANS) and 1,3,5-diphenylhexatriene (DPH). Changes in permeability of liposomes were studied through CF latency. The results of surface properties and liposome interactions suggest that this peptide forms some type of aggregate in water solution that competes with its incorporation at a water–air interface and with its binding to bilayers.

Physicochemical Study of Hydrophobic Derivatives of Collagen Fragments

Collagen fragments of molecular weights ranging from 700 to 3500 were prepared and allowed to react with hexyl and lauryl aldehydes in order to obtain derivatives of different hydrophobicities. Lauryl collagen forms, in aqueous solutions, aggregates that have low tendency to interact with phospholipid mono and bilayers, with reduced surface activity but the ability to entrap ANS molecules. The hexyl derivative shows a greater hydrophobicity in terms of surface activity and interaction with lipids but a lower ability to incorporate ANS. Underivatized collagen shows no lipid interaction in any of the experiments.

Interaction with Phospholipid Mono- and Bi‐layers of HAV‐VP3 (102–121) Sequence by Using Spectroscopic Techniques

Biomedical ChromatographyVolume 11, Issue 2 p. 121-123 Extended Abstract Interaction with Phospholipid Mono- and Bi-layers of HAV-VP3 (102–121) Sequence by Using Spectroscopic Techniques M. Garcia, Corresponding Author M. Garcia Department of Peptide and Protein Chemistry, CID, CSIC, Jordi Girona 18–26, 08034 Barcelona, SpainDepartment of Peptide and Protein Chemistry, CID, CSIC, Jordi Girona 18–26, 08034 Barcelona, SpainSearch for more papers by this authorM. Pujol, M. Pujol Physico-chemical Unit, Faculty of Pharmacy, Pius XII s/n 08028 Barcelona, SpainSearch for more papers by this authorF. Reig, F. Reig Department of Peptide and Protein Chemistry, CID, CSIC, Jordi Girona 18–26, 08034 Barcelona, SpainSearch for more papers by this authorM. A. Alsina, M. A. Alsina Physico-chemical Unit, Faculty of Pharmacy, Pius XII s/n 08028 Barcelona, SpainSearch for more papers by this authorI. Haro, I. Haro Department of Peptide and Protein Chemistry, CID, CSIC, Jordi Girona 18–26, 08034 Barcelona, SpainSearch for more papers by this author M. Garcia, Corresponding Author M. Garcia Department of Peptide and Protein Chemistry, CID, CSIC, Jordi Girona 18–26, 08034 Barcelona, SpainDepartment of Peptide and Protein Chemistry, CID, CSIC, Jordi Girona 18–26, 08034 Barcelona, SpainSearch for more papers by this authorM. Pujol, M. Pujol Physico-chemical Unit, Faculty of Pharmacy, Pius XII s/n 08028 Barcelona, SpainSearch for more papers by this authorF. Reig, F. Reig Department of Peptide and Protein Chemistry, CID, CSIC, Jordi Girona 18–26, 08034 Barcelona, SpainSearch for more papers by this authorM. A. Alsina, M. A. Alsina Physico-chemical Unit, Faculty of Pharmacy, Pius XII s/n 08028 Barcelona, SpainSearch for more papers by this authorI. Haro, I. Haro Department of Peptide and Protein Chemistry, CID, CSIC, Jordi Girona 18–26, 08034 Barcelona, SpainSearch for more papers by this author First published: 04 December 1998 https://doi.org/10.1002/(SICI)1099-0801(199703)11:2<121::AID-BMC662>3.0.CO;2-WCitations: 3AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article.Citing Literature Volume11, Issue2March 1997Pages 121-123 RelatedInformation

Interaction with phospholipid mono- and bilayers of HAV-VP3 (102-121) sequence by using spectroscopic techniques.

Interaction with phospholipid mono- and bilayers of HAV-VP3 (102-121) sequence by using spectroscopic techniques.

Interaction of Enrofloxacin with Phospholipid Mono- and Bilayers

Interaction of Enrofloxacin with Phospholipid Mono- and Bilayers

Resonance energy transfer from a cylindrical distribution of donors to a plane of acceptors. Location of apo-B100 protein on the human low-density lipoprotein particle

The resonance energy transfer (RET) from a cylindrical assembly of donors to acceptors in a plane was investigated, and the dependence the average RET rate (kT) on the cylinder's size, shape, and proximity to the acceptor plane was determined. This geometry provides a model for the RET from a donor-containing protein to acceptors embedded in an associated phospholipid mono- or bilayer. The determination of kT for a series of acceptors at different levels in the phospholipid layer is shown to provide information on the protein's relationship to the phospholipid layer. Two models for the donor (D) and acceptor (A) distributions are employed: (a) The D's and A's are uniformly distributed in the cylinder and the plane, respectively, and analytical expressions for kT in terms of experimental parameters are derived. (b) The RET rates between all D, A pairs within the cylinder and in the plane are calculated and averaged for a large number of random D and A distributions. The average transfer rates obtained by the two approaches are in agreement and the width of the frequency distribution of kT for the latter provides an estimate of the error to be expected when, as is usually the case, the true D and A locations are unknown. This methodology is illustrated by analyzing RET from the 37 tryptophan residues of the apo-B100 protein to a series of pyrenylphosphatidylcholine acceptors inserted in the phospholipid monolayer of the human low-density lipoprotein particle, and it is concluded that significant portions of the protein penetrate the phospholipid layer.

Metabolism of [1- 14C]palmitic acid in sealed brood of the African worker honeybee

1. 1. The fate of [1- 14C]palmitic acid injected into honeybee workers was monitored over the course of metamorphosis. 2. 2. The palmitic acid was recovered from the phospholipid mono-, di- and triglyceride, steriod, free fatty acid and cholesterol ester compartments. 3. 3. Triglycerides constitute the main source of fatty acids used for catabolic and anabolic reactions during honeybee worker development.

A simple model for phase transitions in monolayers and bilayers of lipid molecules

A simple model for first order phase transitions in monomolecular systems is developed and applied to (i) the condensed mesophase – liquid mesophase chain melting transition of phospholipid mono- and bilayers and (ii) a cooperative chain lifting phase transition found in monolayers of diesters with two polar heads. The excluded volume interactions are included in the model by requiring the polar heads to lie on a two-dimensional hexagonal lattice. The attractive van der Waals interactions are assumed to act between averaged molecular configurations of different surface area per polar head. Both the attractive intermolecular interaction and the description of the neighbourhood of the molecules are analyzed in the molecular field approximation. It is shown that the neighbourhood effects are negligible for the chain melting transition, which can then be described by a [Formula: see text] Ising model. They are, however, shown to be important for the chain lifting transition. The last section contains applications to experimental data and comments on the possibility of extending the model to the description of phospholipid mono- and bilayers with impurities.

Studies on Phospholipid Mono‐ and Bilayers

AbstractAbstract Lipids play a fundamental part in the lipid‐protein network of biological membranes. Some of the variations in biological membranes may be brought about by differences in the chemical structure of the lipid constituents. A study was made by the interfacial force‐area characteristics of saturated and highly unsaturated phospho‐lipids and lyso phosphatidyl compounds. The action of some of these phospholipids on lipid bilayers has also been studied. Comparisons were made between the interfacial behavior of in‐dividual phospholipid species which were chem‐ically synthesized and phospholipids from natural sources. The influence of diets on the force‐area characteristics of liver lecithins has been studied. From studies of mixed monolayers of cholesterol and phospholipids it was found that the mean area per molecule in mixed films of cholesterol with (l,2‐distearoyl)‐3‐lecithin and (1,2‐dideca‐noyl)‐3‐lecithin at 22C followed practically the additivity rule. A condensing effect of cholesterol was evident with films of (1‐stearoy1‐2‐1auroy1)‐3‐1ecithin, (l,2‐ditetradecanoyl)‐3‐lecithin, (1‐stearoyl‐2‐oleoyl)‐3‐lecithin, and the correspond‐ing ethanolamine analogue as well as with (l,2‐dioleoyl)‐3‐lecithin at 22C. At 5C the con‐densation effect with (l,2‐ditetradecanoyl)‐3‐lecithin was much reduced.The expanded films of synthetic lecithins and phosphatidylethanolamines containing linoleic or linolenic acid showed no appreciable condensation effects with cholesterol. The behavior of the mixed‐phospholipid films is governed by a number of factors, including van der Waals interactions, configurational entropy effects, and alterations in the structure of water adjacent to the monolayers. These factors depend on chain length and degree of unsaturation.Polyene antibiotics are found to lyse fungi, protozoa, and erythrocytes, but bacteria proto‐plasts and blue‐green algae are not. Cholesterol as well as lecithin were found by some authors to re‐duce the effective polyene antibiotic concentration. It therefore seemed desirable to determine whether polyene antibiotics can interact with lipids other than sterols. Filipin, nystatin, amphotericin B, etruscomycin, and pimaricin readily penetrate monolayers of cholesterol and ergosterol at initial surface pressures greater than the collapse pres‐sure of the antibiotics. Under the same conditions there was essentially no interaction with a variety of pure synthetic phospholipids unless sterol was present. Filipin did not penetrate monolayers prepared from polyene‐insensitive bacteria. The increase in surface pressure of mixed films of phospholipid and cholesterol after the injection of filipin was highly dependent on the relative quantity of sterol as well as on the molar ratio lipid‐polyene antibiotic. From the results of mono‐and bilayer experiments which are in good agree‐ment with the physiological experiments, it is concluded that cholesterol is a necessary mem‐brane constituent for the polyene antibiotic action.