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sPLA2 Wobbles on the Lipid Bilayer between Three Positions, Each Involved in the Hydrolysis Process. Toxins (Basel) 2022; 14:toxins14100669. [PMID: 36287938 PMCID: PMC9610741 DOI: 10.3390/toxins14100669] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2022] [Revised: 09/14/2022] [Accepted: 09/22/2022] [Indexed: 11/17/2022] Open
Abstract
Secreted phospholipases A2 (sPLA2s) are peripheral membrane enzymes that hydrolyze phospholipids in the sn-2 position. The action of sPLA2 is associated with the work of two active sites. One, the interface binding site (IBS), is needed to bind the enzyme to the membrane surface. The other one, the catalytic site, is needed to hydrolyze the substrate. The interplay between sites, how the substrate protrudes to, and how the hydrolysis products release from, the catalytic site remains in the focus of investigations. Here, we report that bee venom PLA2 has two additional interface binding modes and enzyme activity through constant switching between three different orientations (modes of binding), only one of which is responsible for substrate uptake from the bilayer. The finding was obtained independently using atomic force microscopy and molecular dynamics. Switching between modes has biological significance: modes are steps of the enzyme moving along the membrane, product release in biological milieu, and enzyme desorption from the bilayer surface.
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2
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Discerning perturbed assembly of lipids in a model membrane in presence of violacein. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2021; 1863:183647. [PMID: 33989532 DOI: 10.1016/j.bbamem.2021.183647] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 12/20/2020] [Revised: 05/01/2021] [Accepted: 05/07/2021] [Indexed: 12/13/2022]
Abstract
Violacein is a naturally found pigment that is used by some gram negative bacteria to defend themselves from various gram positive bacteria. As a result, this molecule has caught attention for its potential biomedical applications and has already shown promising outcomes as an antiviral, an antibacterial, and an anti-tumor agent. Understanding the interaction of this molecule with a cellular membrane is an essential step to extend its use in the pharmaceutical paradigm. Here, the interaction of violacein with a lipid monolayer formed at the air-water interface is found to depend on electrostatic nature of lipids. In presence of violacein, the two dimensional (2D) pressure-area isotherms of lipids have exhibited changes in their phase transition pressure and in-plane elasticity. To gain insights into the out-of-plane structural organization of lipids in a membrane, X-ray reflectivity (XRR) study on a solid supported lipid monolayer on a hydrophilic substrate has been performed. It has revealed that the increase in membrane thickness is more pronounced in the zwitterionic and positively charged lipids compared to the negatively charged one. Further, the lipid molecules are observed to decrease their tilt angle made with the normal of lipid membrane along with an alteration in their in-plane ordering. This has been quantified by grazing incidence X-ray diffraction (GIXD) experiments on the multilayer membrane formed in an environment with controlled humidity. The structural reorganization of lipid molecules in presence of violacein can be utilized to provide a detailed mechanism of the interaction of this molecule with cellular membrane.
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3
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Munusamy S, Conde R, Bertrand B, Munoz-Garay C. Biophysical approaches for exploring lipopeptide-lipid interactions. Biochimie 2020; 170:173-202. [PMID: 31978418 PMCID: PMC7116911 DOI: 10.1016/j.biochi.2020.01.009] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2019] [Accepted: 01/19/2020] [Indexed: 02/07/2023]
Abstract
In recent years, lipopeptides (LPs) have attracted a lot of attention in the pharmaceutical industry due to their broad-spectrum of antimicrobial activity against a variety of pathogens and their unique mode of action. This class of compounds has enormous potential for application as an alternative to conventional antibiotics and for pest control. Understanding how LPs work from a structural and biophysical standpoint through investigating their interaction with cell membranes is crucial for the rational design of these biomolecules. Various analytical techniques have been developed for studying intramolecular interactions with high resolution. However, these tools have been barely exploited in lipopeptide-lipid interactions studies. These biophysical approaches would give precise insight on these interactions. Here, we reviewed these state-of-the-art analytical techniques. Knowledge at this level is indispensable for understanding LPs activity and particularly their potential specificity, which is relevant information for safe application. Additionally, the principle of each analytical technique is presented and the information acquired is discussed. The key challenges, such as the selection of the membrane model are also been briefly reviewed. A brief overview of topics to understand the generalities of lipopeptide (LP) science. Main analytical techniques used to reveal the interaction and the distorting effect of LP on artificial membranes. Guidelines for selecting of the most adequate membrane models for the given analytical technique.
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Affiliation(s)
- Sathishkumar Munusamy
- Instituto de Ciencias Físicas, Universidad Nacional Autónoma de México, Av. Universidad 2001, Col. Chamilpa, 62210, Cuernavaca, Mexico
| | - Renaud Conde
- Centro de Investigación Sobre Enfermedades Infecciosas, Instituto Nacional de Salud Pública, Cuernavaca, Morelos, Mexico
| | - Brandt Bertrand
- Instituto de Ciencias Físicas, Universidad Nacional Autónoma de México, Av. Universidad 2001, Col. Chamilpa, 62210, Cuernavaca, Mexico
| | - Carlos Munoz-Garay
- Instituto de Ciencias Físicas, Universidad Nacional Autónoma de México, Av. Universidad 2001, Col. Chamilpa, 62210, Cuernavaca, Mexico.
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4
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Rehman J, Sowah-Kuma D, Stevens AL, Bu W, Paige MF. Immiscible Anionic Gemini Surfactant-Perfluorinated Fatty Acid Langmuir Monolayer Films. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2019; 35:10551-10560. [PMID: 31309841 DOI: 10.1021/acs.langmuir.9b01554] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
A new member of the N,N,N',N'-dialkyl-N,N'-diacetate ethylenediamine family of anionic gemini surfactants has been synthesized, and its miscibility with the model perfluorocarbon, perfluorotetradecanoic acid (PF), has been investigated in monolayer films at the air-water interface. Thermodynamics of mixing and the accompanying changes in the mixed film structure have been probed using a combination of compression isotherm measurements supported by Brewster angle microscope imaging and X-ray scattering measurements, and results have been compared with those collected for a previously studied, shorter tail chain variant of the surfactant. Thermodynamic measurements showed that the gemini surfactant and perfluorotetradecanoic acid were immiscible, with weak repulsive interactions, manifesting as small positive deviations from ideal mixing, observed between the two film components. Films were highly textured, with micrometer-scale, phase-separated domains readily detectable. Grazing incidence X-ray diffraction measurements showed that the gemini surfactant was disordered in the monolayers, whereas the perfluorocarbon formed discrete crystallites in the disordered matrix. Despite the small deviations from ideal mixing detected in the thermodynamic measurements, the X-ray measurements indicated that the presence of the gemini perturbs the PF crystal lattice from that of pure PF. Finally, X-ray reflectivity measurements showed that the addition of equimolar PF to the gemini monolayer induces a significant increase in the nominal head group thickness of the film, suggesting that interactions between the two surfactants can lead to structural rearrangements of gemini's head group near to the water surface.
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Affiliation(s)
- Jeveria Rehman
- Department of Chemistry, 110 Science Place , University of Saskatchewan , Saskatoon , Saskatchewan S7N 5C9 , Canada
| | - David Sowah-Kuma
- Department of Chemistry, 110 Science Place , University of Saskatchewan , Saskatoon , Saskatchewan S7N 5C9 , Canada
| | - Amy L Stevens
- Department of Chemistry, 110 Science Place , University of Saskatchewan , Saskatoon , Saskatchewan S7N 5C9 , Canada
| | - Wei Bu
- NSF's ChemMatCARS , The University of Chicago , Chicago , Illinois 60637 , United States
| | - Matthew F Paige
- Department of Chemistry, 110 Science Place , University of Saskatchewan , Saskatoon , Saskatchewan S7N 5C9 , Canada
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5
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Macromolecular crowding and membrane binding proteins: The case of phospholipase A1. Chem Phys Lipids 2019; 218:91-102. [DOI: 10.1016/j.chemphyslip.2018.12.006] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2018] [Revised: 10/10/2018] [Accepted: 12/13/2018] [Indexed: 11/24/2022]
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6
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Joyce P, Gustafsson H, Prestidge CA. Engineering intelligent particle-lipid composites that control lipase-mediated digestion. Adv Colloid Interface Sci 2018; 260:1-23. [PMID: 30119842 DOI: 10.1016/j.cis.2018.08.001] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2018] [Revised: 08/01/2018] [Accepted: 08/02/2018] [Indexed: 12/25/2022]
Abstract
Nanostructured particle-lipid composites have emerged as state-of-the-art carrier systems for poorly water-soluble bioactive molecules due to their ability to control and enhance the lipase-mediated hydrolysis of encapsulated triglycerides, leading to a subsequent improvement in the solubilisation and absorption of encapsulated species. The first generation of particle-lipid composites (i.e. silica-lipid hybrid (SLH) microparticles) were designed and fabricated by spray drying a silica nanoparticle-stabilised Pickering emulsion, to create a novel three-dimensional architecture, whereby lipid droplets were encapsulated within a porous matrix support. The development of SLH microparticles has acted as a solid foundation for the synthesis of several next generation particle-lipid composites, including polymer-lipid hybrid (PLH) and clay-lipid hybrid systems (CLH), which present lipase with unique lipid microenvironments for optimised lipolysis. This review details the methods utilised to engineer lipid hybrid particles and the strategic investigations that have been performed to determine the influence of key material characteristics on digestion enzyme activity. In doing so, this provides insight into manipulating the mechanism of lipase action through the intelligent design of lipid-based biomaterials for their use in drug delivery formulations and novel functional foods.
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7
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Sowah-Kuma D, Fransishyn KM, Cayabyab C, Martynowycz MW, Kuzmenko I, Paige MF. Molecular-Level Structure and Packing in Phase-Separated Arachidic Acid-Perfluorotetradecanoic Acid Monolayer Films. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2018; 34:10673-10683. [PMID: 30102043 DOI: 10.1021/acs.langmuir.8b02291] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Synchrotron-based X-ray scattering measurements of phase-separated surfactant monolayers at the air-water interface provide molecular-level structural information about the packing and ordering of film components. In this work, grazing incidence X-ray diffraction (GIXD) and X-ray reflectivity (XR) measurements were used to collect crystallographic structural information for binary mixed monolayers of arachidic acid (AA, C19H39COOH) with perfluorotetradecanoic acid (PA, C13F27COOH), a system that has previously been investigated using a variety of thermodynamic and micron-scale structural characterization methods. GIXD measurements at surface pressures of π = 5, 15, and 30 mN/m indicated that AA in pure and mixed films forms a rectangular lattice at π = 5 and 15 mN/m but a hexagonal lattice at π = 30 mN/m. PA formed hexagonal lattices under all conditions, with films being highly ordered and crystalline (as determined by Bragg peak width) at even the lowest surface pressures investigated. Phase separation occurred for all mixed monolayer film compositions and surface pressures, manifesting as diffraction peaks characteristic of the individual components appearing at different in-plane scattering vector qxy. For both pure and mixed films, the molecular tilt angle of the AA hydrocarbon chain toward the nearest-neighbor was substantial at low pressures but decreased with increasing pressure. The PA fluorocarbon chain showed negligible molecular tilt under all conditions, and was oriented normal to the subphase surface regardless of surface pressure or the presence of AA in the films. In all cases, the two components in the mixed film behaved entirely independently of film composition, which is exactly the expected result for a fully phase-separated, immiscible system. XR measurements of film thickness at the air-water interface supported these results; overall film thickness approached the calculated ideal surfactant tail lengths with increasing surface pressure, indicating nearly normal oriented surfactants. The overall surfactant packing and crystallographic features of the mixed monolayers are discussed in terms of the lipophobic nature of the perfluorinated surfactant as well as in context of thermodynamic miscibility and domain structure formation reported elsewhere in the literature for these mixed monolayer systems.
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Affiliation(s)
- David Sowah-Kuma
- Department of Chemistry , University of Saskatchewan , Saskatoon , Saskatchewan S7N 5A2 , Canada
| | - Kyle M Fransishyn
- Department of Chemistry , University of Saskatchewan , Saskatoon , Saskatchewan S7N 5A2 , Canada
| | - Chelsea Cayabyab
- Department of Chemistry , University of Saskatchewan , Saskatoon , Saskatchewan S7N 5A2 , Canada
| | - Michael W Martynowycz
- Advanced Photon Source , Argonne National Lab , Lemont , Illinois 60439 , United States
| | - Ivan Kuzmenko
- Advanced Photon Source , Argonne National Lab , Lemont , Illinois 60439 , United States
| | - Matthew F Paige
- Department of Chemistry , University of Saskatchewan , Saskatoon , Saskatchewan S7N 5A2 , Canada
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8
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Wójcik A, Perczyk P, Wydro P, Flasiński M, Broniatowski M. Interactions of Long-Chain Perfluorotelomer Alcohol and Perfluorinated Hydrocarbons with Model Decomposer Membranes. J Phys Chem B 2018; 122:7340-7352. [DOI: 10.1021/acs.jpcb.8b05194] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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9
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Sachan AK, Choi SQ, Kim KH, Tang Q, Hwang L, Lee KYC, Squires TM, Zasadzinski JA. Interfacial rheology of coexisting solid and fluid monolayers. SOFT MATTER 2017; 13:1481-1492. [PMID: 28125114 PMCID: PMC5720834 DOI: 10.1039/c6sm02797k] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
Biologically relevant monolayer and bilayer films often consist of micron-scale high viscosity domains in a continuous low viscosity matrix. Here we show that this morphology can cause the overall monolayer fluidity to vary by orders of magnitude over a limited range of monolayer compositions. Modeling the system as a two-dimensional suspension in analogy with classic three-dimensional suspensions of hard spheres in a liquid solvent explains the rheological data with no adjustable parameters. In monolayers with ordered, highly viscous domains dispersed in a continuous low viscosity matrix, the surface viscosity increases as a power law with the area fraction of viscous domains. Changing the phase of the continuous matrix from a disordered fluid phase to a more ordered, condensed phase dramatically changes the overall monolayer viscosity. Small changes in the domain density and/or continuous matrix composition can alter the monolayer viscosity by orders of magnitude.
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Affiliation(s)
- A K Sachan
- Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, Minnesota 55455, USA.
| | - S Q Choi
- Departments of Chemical and Biomolecular Engineering and KINC, KAIST, Daejeon, 305-701, Korea
| | - K H Kim
- Departments of Chemical and Biomolecular Engineering and KINC, KAIST, Daejeon, 305-701, Korea
| | - Q Tang
- Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, Minnesota 55455, USA.
| | - L Hwang
- Department of Chemistry, Institute for Biophysical Dynamics, and James Franck Institute, University of Chicago, Chicago, Illinois 60637, USA
| | - K Y C Lee
- Department of Chemistry, Institute for Biophysical Dynamics, and James Franck Institute, University of Chicago, Chicago, Illinois 60637, USA
| | - T M Squires
- Department of Chemical Engineering, University of California, Santa Barbara, CA 93106, USA
| | - J A Zasadzinski
- Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, Minnesota 55455, USA.
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10
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Majewski J, André S, Jones E, Chi E, Gabius HJ. X-ray reflectivity and grazing incidence diffraction studies of interaction between human adhesion/growth-regulatory galectin-1 and DPPE-GM1 lipid monolayer at an air/water interface. BIOCHEMISTRY (MOSCOW) 2016; 80:943-56. [PMID: 26542007 DOI: 10.1134/s0006297915070135] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
The specific interaction of ganglioside GM1 with the homodimeric (prototype) endogenous lectin galectin-1 triggers growth regulation in tumor and activated effector T cells. This proven biorelevance directed interest to studying association of the lectin to a model surface, i.e. a 1,2-dihexadecanoyl-sn-glycero-3-phosphoethanolamine/ganglioside GM1 (80 : 20 mol%) monolayer, at a bioeffective concentration. Surface expansion by the lectin insertion was detected at a surface pressure of 20 mN/m. On combining the methods of grazing incidence X-ray diffraction and X-ray reflectivity, a transient decrease in lipid-ordered phase of the monolayer was observed. The measured electron density distribution indicated that galectin-1 is oriented with its long axis in the surface plane, ideal for cis-crosslinking. The data reveal a conspicuous difference to the way the pentameric lectin part of the cholera toxin, another GM1-specific lectin, is bound to the monolayer. They also encourage further efforts to monitor effects of structurally different members of the galectin family such as the functionally antagonistic chimera-type galectin-3.
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Affiliation(s)
- J Majewski
- Manuel Lujan Jr. Neutron Scattering Center, Los Alamos Neutron Science Center, Los Alamos National Laboratory, Los Alamos, NM, USA
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11
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Studies on the interactions of bisphenols with anionic phospholipids of decomposer membranes in model systems. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2016; 1858:756-66. [DOI: 10.1016/j.bbamem.2016.01.017] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/06/2015] [Revised: 01/03/2016] [Accepted: 01/20/2016] [Indexed: 11/21/2022]
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12
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Clifton LA, Skoda MA, Le Brun A, Ciesielski F, Kuzmenko I, Holt SA, Lakey JH. Effect of divalent cation removal on the structure of gram-negative bacterial outer membrane models. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2015; 31:404-12. [PMID: 25489959 PMCID: PMC4295546 DOI: 10.1021/la504407v] [Citation(s) in RCA: 223] [Impact Index Per Article: 24.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/10/2014] [Revised: 12/09/2014] [Indexed: 05/18/2023]
Abstract
The Gram-negative bacterial outer membrane (GNB-OM) is asymmetric in its lipid composition with a phospholipid-rich inner leaflet and an outer leaflet predominantly composed of lipopolysaccharides (LPS). LPS are polyanionic molecules, with numerous phosphate groups present in the lipid A and core oligosaccharide regions. The repulsive forces due to accumulation of the negative charges are screened and bridged by the divalent cations (Mg(2+) and Ca(2+)) that are known to be crucial for the integrity of the bacterial OM. Indeed, chelation of divalent cations is a well-established method to permeabilize Gram-negative bacteria such as Escherichia coli. Here, we use X-ray and neutron reflectivity (XRR and NR, respectively) techniques to examine the role of calcium ions in the stability of a model GNB-OM. Using XRR we show that Ca(2+) binds to the core region of the rough mutant LPS (RaLPS) films, producing more ordered structures in comparison to divalent cation free monolayers. Using recently developed solid-supported models of the GNB-OM, we study the effect of calcium removal on the asymmetry of DPPC:RaLPS bilayers. We show that without the charge screening effect of divalent cations, the LPS is forced to overcome the thermodynamically unfavorable energy barrier and flip across the hydrophobic bilayer to minimize the repulsive electrostatic forces, resulting in about 20% mixing of LPS and DPPC between the inner and outer bilayer leaflets. These results reveal for the first time the molecular details behind the well-known mechanism of outer membrane stabilization by divalent cations. This confirms the relevance of the asymmetric models for future studies of outer membrane stability and antibiotic penetration.
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Affiliation(s)
- Luke A. Clifton
- ISIS
Pulsed Neutron and Muon Source, Science and Technology Facilities
Council, Rutherford Appleton Laboratory, Harwell Science and Innovation Campus, Didcot, Oxfordshire, OX11 OQX, United Kingdom
- E-mail:
| | - Maximilian
W. A. Skoda
- ISIS
Pulsed Neutron and Muon Source, Science and Technology Facilities
Council, Rutherford Appleton Laboratory, Harwell Science and Innovation Campus, Didcot, Oxfordshire, OX11 OQX, United Kingdom
| | - Anton
P. Le Brun
- Bragg
Institute, Australian Nuclear Science and
Technology Organisation, Locked Bag 2001, Kirrawee DC, NSW 2232, Australia
| | - Filip Ciesielski
- ISIS
Pulsed Neutron and Muon Source, Science and Technology Facilities
Council, Rutherford Appleton Laboratory, Harwell Science and Innovation Campus, Didcot, Oxfordshire, OX11 OQX, United Kingdom
| | - Ivan Kuzmenko
- Advanced
Photon Source , Argonne National Laboratories, Argonne, Illinois 60439, United States
| | - Stephen A. Holt
- Bragg
Institute, Australian Nuclear Science and
Technology Organisation, Locked Bag 2001, Kirrawee DC, NSW 2232, Australia
| | - Jeremy H. Lakey
- Institute
for Cell and Molecular Biosciences, Newcastle
University, Framlington
Place, Newcastle upon Tyne NE2 4HH, United Kingdom
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13
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Choi S, Kim K, Fellows CM, Cao KD, Lin B, Lee KYC, Squires TM, Zasadzinski JA. Influence of molecular coherence on surface viscosity. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2014; 30:8829-38. [PMID: 24991992 PMCID: PMC4334248 DOI: 10.1021/la501615g] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
Adding small fractions of cholesterol decreases the interfacial viscosity of dipalmitoylphosphatidylcholine (DPPC) monolayers by an order of magnitude per wt %. Grazing incidence X-ray diffraction shows that cholesterol at these small fractions does not mix ideally with DPPC but rather induces nanophase separated structures of an ordered, primarily DPPC phase bordered by a line-active, disordered, mixed DPPC-cholesterol phase. We propose that the free area in the classic Cohen and Turnbull model of viscosity is inversely proportional to the number of molecules in the coherence area, or product of the two coherence lengths. Cholesterol significantly reduces the coherence area of the crystals as well as the interfacial viscosity. Using this free area collapses the surface viscosity data for all surface pressures and cholesterol fractions to a universal logarithmic relation. The extent of molecular coherence appears to be a fundamental factor in determining surface viscosity in ordered monolayers.
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Affiliation(s)
- Siyoung
Q. Choi
- Chemical
Engineering and Materials Science, University
of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Kyuhan Kim
- Department
of Chemical Engineering, University of California, Santa Barbara, California 93106, United States
| | - Colin M. Fellows
- Department
of Chemical Engineering, University of California, Santa Barbara, California 93106, United States
| | - Kathleen D. Cao
- Department
of Chemistry and James Franck Institute, University of Chicago, Chicago, Illinois 60637, United States
| | - Binhua Lin
- Center
for Advanced Radiation Sources and James Franck Institute, University of Chicago, Chicago, Illinois 60637, United States
| | - Ka Yee C. Lee
- Department
of Chemistry and James Franck Institute, University of Chicago, Chicago, Illinois 60637, United States
| | - Todd M. Squires
- Department
of Chemical Engineering, University of California, Santa Barbara, California 93106, United States
| | - Joseph A. Zasadzinski
- Chemical
Engineering and Materials Science, University
of Minnesota, Minneapolis, Minnesota 55455, United States
- E-mail: . Phone: 612-626-2957
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14
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Andreev K, Bianchi C, Laursen JS, Citterio L, Hein-Kristensen L, Gram L, Kuzmenko I, Olsen CA, Gidalevitz D. Guanidino groups greatly enhance the action of antimicrobial peptidomimetics against bacterial cytoplasmic membranes. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2014; 1838:2492-2502. [PMID: 24878450 DOI: 10.1016/j.bbamem.2014.05.022] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2013] [Revised: 05/11/2014] [Accepted: 05/19/2014] [Indexed: 11/18/2022]
Abstract
Antimicrobial peptides or their synthetic mimics are a promising class of potential new antibiotics. Herein we assess the effect of the type of cationic side chain (i.e., guanidino vs. amino groups) on the membrane perturbing mechanism of antimicrobial α-peptide-β-peptoid chimeras. Langmuir monolayers composed of 1,2-dipalmitoyl-sn-glycero-3-phosphatidylglycerol (DPPG) were used to model cytoplasmic membranes of both Gram-positive and Gram-negative bacteria, while lipopolysaccharide Kdo2-lipid A monolayers were mimicking the outer membrane of Gram-negative species. We report the results of the measurements using an array of techniques, including high-resolution synchrotron surface X-ray scattering, epifluorescence microscopy, and in vitro antimicrobial activity to study the molecular mechanisms of peptidomimetic interaction with bacterial membranes. We found guanidino group-containing chimeras to exhibit greater disruptive activity on DPPG monolayers than the amino group-containing analogues. However, this effect was not observed for lipopolysaccharide monolayers where the difference was negligible. Furthermore, the addition of the nitrobenzoxadiazole fluorophore did not reduce the insertion activity of these antimicrobials into both model membrane systems examined, which may be useful for future cellular localization studies.
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Affiliation(s)
- Konstantin Andreev
- Center for Molecular Study of Condensed Soft Matter (μCoSM), Pritzker Institute of Biomedical Science and Engineering and Department of Physics, Illinois Institute of Technology, 3440 S. Dearborn St., Chicago, IL 60616 (USA)
| | - Christopher Bianchi
- Center for Molecular Study of Condensed Soft Matter (μCoSM), Pritzker Institute of Biomedical Science and Engineering and Department of Physics, Illinois Institute of Technology, 3440 S. Dearborn St., Chicago, IL 60616 (USA)
| | - Jonas S Laursen
- Department of Chemistry, Technical University of Denmark, Kemitorvet 207, DK-2800 Kgs. Lyngby (Denmark)
| | - Linda Citterio
- Department of Systems Biology, Technical University of Denmark, Matematiktorvet 301, DK-2800 Kgs. Lyngby (Denmark)
| | - Line Hein-Kristensen
- , National Food Institute, Technical University of Denmark, Søltofts Plads 221, DK-2800, Kgs Lyngby (Denmark)
| | - Lone Gram
- Department of Systems Biology, Technical University of Denmark, Matematiktorvet 301, DK-2800 Kgs. Lyngby (Denmark)
| | - Ivan Kuzmenko
- Advanced Photon Source, Argonne National Laboratory, 9700 S. Cass Ave., Lemont, IL 60439 (USA)
| | - Christian A Olsen
- Department of Chemistry, Technical University of Denmark, Kemitorvet 207, DK-2800 Kgs. Lyngby (Denmark)
| | - David Gidalevitz
- Center for Molecular Study of Condensed Soft Matter (μCoSM), Pritzker Institute of Biomedical Science and Engineering and Department of Physics, Illinois Institute of Technology, 3440 S. Dearborn St., Chicago, IL 60616 (USA)
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15
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Le Brun A, Clifton LA, Halbert CE, Lin B, Meron M, Holden PJ, Lakey JH, Holt SA. Structural characterization of a model gram-negative bacterial surface using lipopolysaccharides from rough strains of Escherichia coli. Biomacromolecules 2013; 14:2014-22. [PMID: 23617615 PMCID: PMC3679557 DOI: 10.1021/bm400356m] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2013] [Revised: 04/18/2013] [Indexed: 12/29/2022]
Abstract
Lipopolysaccharides (LPS) make up approximately 75% of the Gram-negative bacterial outer membrane (OM) surface, but because of the complexity of the molecule, there are very few model OMs that include LPS. The LPS molecule consists of lipid A, which anchors the LPS within the OM, a core polysaccharide region, and a variable O-antigen polysaccharide chain. In this work we used RcLPS (consisting of lipid A plus the first seven sugars of the core polysaccharide) from a rough strain of Escherichia coli to form stable monolayers of LPS at the air-liquid interface. The vertical structure RcLPS monolayers were characterized using neutron and X-ray reflectometry, while the lateral structure was investigated using grazing incidence X-ray diffraction and Brewster angle microscopy. It was found that RcLPS monolayers at surface pressures of 20 mN m(-1) and above are resolved as hydrocarbon tails, an inner headgroup, and an outer headgroup of polysaccharide with increasing solvation from tails to outer headgroups. The lateral organization of the hydrocarbon lipid chains displays an oblique hexagonal unit cell at all surface pressures, with only the chain tilt angle changing with surface pressure. This is in contrast to lipid A, which displays hexagonal or, above 20 mN m(-1), distorted hexagonal packing. This work provides the first complete structural analysis of a realistic E. coli OM surface model.
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Affiliation(s)
- Anton
P. Le Brun
- Bragg Institute, Australian Nuclear Science and Technology Organisation, Locked Bag 2001, Kirrawee DC, NSW 2232, Australia
| | - Luke A. Clifton
- ISIS Neutron Facility, STFC Rutherford
Appleton Laboratory, Didcot, Oxfordshire
OX11 0QX, United Kingdom
| | - Candice E. Halbert
- Spallation Neutron Source, Oak Ridge National Laboratory, Oak Ridge, Tennessee
37831, United States
| | - Binhua Lin
- Consortium
of Advanced Radiation
Sources (CARS), University of Chicago,
Chicago, Illinois 60637, United States
| | - Mati Meron
- Consortium
of Advanced Radiation
Sources (CARS), University of Chicago,
Chicago, Illinois 60637, United States
| | - Peter J. Holden
- Bragg Institute, Australian Nuclear Science and Technology Organisation, Locked Bag 2001, Kirrawee DC, NSW 2232, Australia
| | - Jeremy H. Lakey
- Institute for Cell and Molecular
Biosciences, Newcastle University, Framlington
Place, Newcastle upon Tyne NE2 4HH, United Kingdom
| | - Stephen A. Holt
- Bragg Institute, Australian Nuclear Science and Technology Organisation, Locked Bag 2001, Kirrawee DC, NSW 2232, Australia
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16
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Self-organization of non-amphiphilic molecules. Studies of thin films of long-chain homologous dialkylthioethers at the water/air interface. J Colloid Interface Sci 2013; 395:176-84. [PMID: 23380401 DOI: 10.1016/j.jcis.2012.12.055] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2012] [Revised: 12/25/2012] [Accepted: 12/26/2012] [Indexed: 11/21/2022]
Abstract
In contrast to classical surfactants, the knowledge about the self-organization of alkanes and their hydrophobic derivatives is still limited. In this paper, we present the results of the studies of self-assembly of long-chain dialkylthioethers at the air/water interface. The substitution of one methylene group by the thioether divalent sulfur introduces significant dipole moment to the alkane chain without affecting the hydrophobicity, which profoundly influences the self-assembly of these molecules. Depending on the location of the thioether group in the hydrophobic chain, the investigated molecules can form Langmuir monolayers, which are stabilized by the thioether-water H-bonds formation, or random multilayers. The structures of the monolayers were investigated with the application of Grazing Incidence X-ray Diffraction. To elucidate important structural differences between thioether and alkane monolalyers of the same hydrocarbon chain length, we applied the methods of quantum chemistry (ETS-NOCV calculations). It turned out that the introduction of one sulfur atom affects the distribution of electron density not only in the proximity of this atom but generally along the chain. The combination of experimental and calculation methods provides to the better understanding of the fundamental question of the self-organization of long-chain alkanes and their non-amphiphilic derivatives at interfaces.
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17
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Dannehl C, Gutsmann T, Brezesinski G. Surface activity and structures of two fragments of the human antimicrobial LL-37. Colloids Surf B Biointerfaces 2013; 109:129-35. [PMID: 23624281 DOI: 10.1016/j.colsurfb.2013.03.030] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2013] [Revised: 03/22/2013] [Accepted: 03/25/2013] [Indexed: 10/27/2022]
Abstract
Two fragments of the antimicrobial peptide LL-37 (LL-32 and LL-20) have been characterized in adsorption layers at the air/buffer interface by infrared reflection absorption spectroscopy (IRRAS) and X-ray reflectivity (XR) measurements. As shown in previous work, LL-32 exhibits an increased antimicrobial activity compared to LL-37, while LL-20 is almost not active. It is shown in this work that the peptides differ drastically in their surface activity (equilibrium adsorption pressure) and their secondary structure, when they are adsorbed to the air/buffer interface. As concluded from the CD spectra, both peptides are unstructured in bulk. That means that the adsorption of the peptides to the air/buffer interface is connected to a secondary structure change. While LL-32 transforms into an α-helix lying flat at the buffer surface, with a helix diameter of 17Å, LL-20 adopts a partly unstructured conformation. The dichroic ratio of LL-20 is reduced and the electron density profile shows the formation of a second layer. The ability of LL-32 to form a complete α-helical structure at the interface is in good agreement with its higher antimicrobial activity.
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Affiliation(s)
- Claudia Dannehl
- Max Planck Institute of Colloids and Interfaces, 14424 Potsdam, Germany
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18
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Flasiński M, Broniatowski M, Wydro P, Hąc-Wydro K, Dynarowicz-Łątka P. Behavior of platelet activating factor in membrane-mimicking environment. Langmuir monolayer study complemented with grazing incidence X-ray diffraction and Brewster angle microscopy. J Phys Chem B 2012; 116:10842-55. [PMID: 22834697 DOI: 10.1021/jp302907e] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
1-O-octadecyl-2-acetyl-sn-glycero-3-phosphocholine (PAF) belonging to the class of single-chained ether phospholipids is widely known from its essential biological activities. There is a growing body of evidence that some significant aspects of PAF actions are connected with its capability to direct intercalation into biomembranes' environment. Although this mechanism is of great importance in the perspective of understanding PAF implications in various physiological processes, in the literature, there is a lack of studies devoted to this subject. It is still unknown which is the exact influence of membrane composition, molecular organization, and its other properties on the PAF impact on cells and tissues. Unfortunately, the biological studies carried out on cell cultures do not provide satisfactory results, mainly because of the complexity of natural systems. In order to obtain insight into the behavior of PAF in a lipid environment at the molecular level, the application of appropriate model systems is required. Among them, Langmuir monolayers are very often applied as a simple but very efficient platform for studies of the interactions between membrane lipids. In the present paper, special attention is focused on the issue concerning the interactions between PAF and two representatives of membrane components occurring mainly in the outer leaflet of natural bilayers, namely, cholesterol and DPPC. The application of Langmuir monolayers enabled us to construct the effective model mimicking the exogenous incorporation of PAF into membrane environment. On the basis of the obtained results, a thorough discussion was carried out and the conclusions derived from the traditional thermodynamic analysis were confronted with microscopic analysis of surface domains and the GIXD results. The selection of experimental techniques enables us to obtain information regarding the miscibility and interactions in the binary mixed films as well as the molecular organization of film-forming molecules on water surface. The experiments revealed that the addition of the investigated single-chained ether phospholipid into both cholesterol and DPPC monolayers causes a considerable decrease of monolayer condensation. On the basis of thermodynamic analysis, it was found that PAF mixes and consequently interacts strongly with cholesterol, whereas its interactions with DPPC are thermodynamically unfavorable. Differences between the PAF influence on cholesterol and DPPC monolayer found its corroboration in the results obtained with the GIXD technique. Namely, the monolayer of DPPC can incorporate more PAF than the model membrane containing cholesterol. The obtained results indicate that short chained sn-2 ether phospholipid is able to modify model membrane properties in a concentration-dependent way.
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Affiliation(s)
- Michał Flasiński
- Faculty of Chemistry, Jagiellonian University, Ingardena 3, 30-060 Kraków, Poland.
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19
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Broniatowski M, Flasiński M, Wydro P. Investigation of the interactions of lupane type pentacyclic triterpenes with outer leaflet membrane phospholipids--Langmuir monolayer and synchrotron X-ray scattering study. J Colloid Interface Sci 2012; 381:116-24. [PMID: 22682981 DOI: 10.1016/j.jcis.2012.05.020] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2012] [Revised: 05/08/2012] [Accepted: 05/09/2012] [Indexed: 01/11/2023]
Abstract
Lupane type pentacyclic triterpenes (LTs) are pharmacologically active natural products isolated from different plants. They have broad spectrum of therapeutic action ranging from anticancer via anti-HIV, antibiotic to anti-inflammatory and anti-protozoal activity. Many scientific papers underline that the key stage in the LT mechanism of action is their incorporation into cellular membrane and the interaction with the structural lipids. In our research we apply Langmuir monolayers as a versatile platform for the investigation of these phenomena, since till now important aspects concerning this issue are incomprehensible. We focus our attention on the interactions of lupeol and betulinic acid with choline-headgroup structural lipids: a representative of saturated glycerophosphatidylcholines (DPPCs), and octadecyl-sphingomyelin--a representative of membrane sphingolipids. Application of complementary physicochemical techniques such as the Langmuir technique, Brewster angle microscopy, and grazing incidence X-ray diffraction supported by thermodynamic analysis enabled us to investigate the intermolecular interactions in such binary model systems. Our results corroborate that LT is miscible with the outer leaflet membrane phospholipids, both DPPC and SM in the whole range of mole ratios. Moreover, the introduction of LT into the phospholipid film, even in small proportion, leads to the loss of periodical ordering of the phospholipid molecules and the disappearance of the diffraction signal as observed by GIXD. Our results also proved that LT does not form any surface complexes of fixed stoichiometry resembling the well characterized lipid rafts.
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Affiliation(s)
- Marcin Broniatowski
- Jagiellonian University, Faculty of Chemistry, Ingardena 3, 30-060 Kraków, Poland.
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20
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Risović D, Frka S, Kozarac Z. The Structure of Percolating Lipid Monolayers. J Colloid Interface Sci 2012; 373:116-21. [DOI: 10.1016/j.jcis.2011.12.009] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2011] [Revised: 12/01/2011] [Accepted: 12/04/2011] [Indexed: 10/14/2022]
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21
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Broniatowski M, Flasiński M, Wydro P. Lupane-type pentacyclic triterpenes in Langmuir monolayers: a synchrotron radiation scattering study. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2012; 28:5201-5210. [PMID: 22360277 DOI: 10.1021/la300024f] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Lupane-type pentacyclic triterpenes (lupeol, betulin, and betulinic acid) are natural products isolated from various plant sources. The terpenes exhibit a vast spectrum of biological activity and are applied in therapies for different diseases, among which the anticancer, anti-HIV, antihypercholesteremic, and antiinflammatory are the most promising. These chemicals possess amphiphilic structure and were proved to interact strongly with biomembranes, which can be the key stage in their mechanism of action. In our studies, we applied Langmuir monolayers as versatile models of biomembranes. It turned out that the three investigated terpenes are capable of stable monolayer formation; however, these monolayers differ profoundly regarding their physicochemical characteristics. In our research, we applied the Langmuir technique (surface pressure-mean molecular area (π-A) isotherm registration) coupled with Brewster angle microscopy (BAM), but the main focus was on the synchrotron radiation scattering method, grazing incidence X-ray diffraction (GIXD), which provides information on the amphiphilic molecule ordering in the angström scale. It was proved that all the investigated terpenes form crystalline phases in their monolayers. In the case of lupeol, only the closely packed upright phase was observed, whereas for betulin and betulinic acid, the phase situation was more complex. Betulinic acid molecules can be organized in an upright phase, which is crystalline, and in a tilted phase, which is amorphous. The betulin film is a conglomerate of an upright crystalline monolayer phase, tilted amorphous monolayer phase, and a crystalline tilted bilayer. In our paper, we discuss the factors leading to the formation of the observed phases and the implications of our results to the therapeutic applications of the native lupane-type triterpenes.
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22
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Affiliation(s)
- Francisco Zaera
- Department of Chemistry, University of California, Riverside, California 92521, United States
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23
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X-ray scattering studies of model lipid membrane interacting with purothionin provide support for a previously proposed mechanism of membrane lysis. EUROPEAN BIOPHYSICS JOURNAL: EBJ 2009; 39:1155-65. [DOI: 10.1007/s00249-009-0568-0] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/21/2009] [Revised: 11/15/2009] [Accepted: 11/19/2009] [Indexed: 10/20/2022]
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24
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Ziblat R, Kjaer K, Leiserowitz L, Addadi L. Structure of Cholesterol/Lipid Ordered Domains in Monolayers and Single Hydrated Bilayers. Angew Chem Int Ed Engl 2009. [DOI: 10.1002/ange.200903847] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
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25
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Ziblat R, Kjaer K, Leiserowitz L, Addadi L. Structure of Cholesterol/Lipid Ordered Domains in Monolayers and Single Hydrated Bilayers. Angew Chem Int Ed Engl 2009; 48:8958-61. [DOI: 10.1002/anie.200903847] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
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26
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Neville F, Ivankin A, Konovalov O, Gidalevitz D. A comparative study on the interactions of SMAP-29 with lipid monolayers. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2009; 1798:851-60. [PMID: 19800862 DOI: 10.1016/j.bbamem.2009.09.017] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/15/2009] [Revised: 09/08/2009] [Accepted: 09/24/2009] [Indexed: 11/26/2022]
Abstract
This work investigates the discrimination of lipid monolayers by the ovine antimicrobial peptide SMAP-29 and compares it to that of the human LL-37 peptide. Fluid phospholipid monolayers were formed in a Langmuir trough and subsequently studied with the X-ray scattering techniques of X-ray reflectivity and grazing incidence X-ray diffraction. Any changes in the phospholipid structure after injection of peptide under the monolayer were considered to be due to interactions between the peptides and lipids. The data show that SMAP-29 discriminates against negatively charged phospholipids in a similar way to LL-37. However, it is even more interesting to note that despite a higher concentration of SMAP-29 near the monolayer, ensured by its greater charge as compared to LL-37, the amount of SMAP-29 needed to observe monolayer disruption was around three and a half times the number of molecules of LL-37 used to see similar changes with the same system. This result suggests that the structure, amino acid sequence or size of the peptide may well be as important as electrical charge and therefore gives many implications for the further study of antimicrobial peptides with regards to novel drug design and development.
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Affiliation(s)
- Frances Neville
- School of Process, Environmental and Materials Engineering, University of Leeds, Leeds LS29JT, UK
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27
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Lifshitz Y, Golan Y, Konovalov O, Berman A. Structural transitions in polydiacetylene Langmuir films. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2009; 25:4469-4477. [PMID: 19366221 DOI: 10.1021/la8029038] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Polydiacetylene (PDA) Langmuir films (LFs) were investigated directly at the air/water interface using in situ synchrotron grazing incidence X-ray diffraction, and ex situ transmissison electron microscopy and diffraction. The films were compressed and polymerized on pure water. A crystallographic model describes the structures and phase transitions of the unpolymerized (monomer) film, via the metastable (blue phase), to the fully stable PDA red phase as a function of irradiation dose. The monomer-to-blue-to-red chromatic phase transitions are accompanied by changes in the in-plane crystal structure and pendant chains packing arrangement from arced alkyl chains (in the monomer and blue phases) to near-vertical closely packed chains in the red phase. Notably, the characteristic linear strand morphology of PDA films can be explained as a direct result of the marked decrease in spacing between adjacent polymer chains upon transition from the blue to the red phase.
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Affiliation(s)
- Yevgeniy Lifshitz
- Department of Materials Engineering, Ilse Katz Institute of Nanoscience and Nanotechnology, Beer-Sheva, Israel
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28
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Belman N, Acharya S, Konovalov O, Vorobiev A, Israelachvili J, Efrima S, Golan Y. Hierarchical assembly of ultranarrow alkylamine-coated ZnS nanorods: a synchrotron surface X-ray diffraction study. NANO LETTERS 2008; 8:3858-3864. [PMID: 18823147 DOI: 10.1021/nl802287h] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
The packing of anisotropic ultranarrow nanoparticles ( r <or= 0.5 nm) in Langmuir films was investigated for two types of nanoparticles: short ZnS wires coated with tetradecylamine and ZnS rods coated with octadecylamine. In situ grazing incidence small-angle X-ray scattering (GISAXS) revealed the formation, even under zero pressure, of ordered superstructures on the water surface consisting of alternating nanoparticles. A hierarchical "packing model" is proposed, based on GISAXS, transmission electron microscopy, thermogravimetric analysis, and grazing incidence X-ray diffraction of pure surfactant Langmuir films.
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Affiliation(s)
- Nataly Belman
- Department of Materials Engineering, Ilse Katz Institute of Nanotechnology, Ben-Gurion University of the Negev, Beer-Sheva 84105, Israel
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29
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Part II: diffraction from two-dimensional cholera toxin crystals bound to their receptors in a lipid monolayer. Biophys J 2008; 95:641-7. [PMID: 18359801 DOI: 10.1529/biophysj.107.120808] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The structure of cholera toxin (CTAB(5)) bound to its putative ganglioside receptor, galactosyl-N-acetylgalactosaminyl (N-acetyl-neuraminyl) galactosylglucosylceramide (GM(1)), in a lipid monolayer at the air-water interface has been studied utilizing grazing incidence x-ray diffraction. Cholera toxin is one of very few proteins to be crystallized in two dimensions and characterized in a fully hydrated state. The observed grazing incidence x-ray diffraction Bragg peaks indicated cholera toxin was ordered in a hexagonal lattice and the order extended 600-800 A. The pentameric binding portion of cholera toxin (CTB(5)) improved in-plane ordering over the full toxin (CTAB(5)) especially at low pH. Disulfide bond reduction (activation of the full toxin) also increased the protein layer ordering. These findings are consistent with A-subunit flexibility and motion, which cause packing inefficiencies and greater disorder of the protein layer. Corroborative out-of-plane diffraction (Bragg rod) analysis indicated that the scattering units in the cholera layer with CTAB(5) shortened after disulfide bond reduction of the A subunit. These studies, together with Part I results, revealed key changes in the structure of the cholera toxin-lipid system under different pH conditions.
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30
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Neville F, Ishitsuka Y, Hodges CS, Konovalov O, Waring AJ, Lehrer R, Lee KYC, Gidalevitz D. Protegrin interaction with lipid monolayers: Grazing incidence X-ray diffraction and X-ray reflectivity study. SOFT MATTER 2008; 4:1665-1674. [PMID: 19672319 PMCID: PMC2723866 DOI: 10.1039/b718295c] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
Interactions of the antimicrobial peptide protegrin-1 (PG-1) with phospholipid monolayers have been investigated by using grazing incidence X-ray diffraction (GIXD) and specular X-ray reflectivity (XR). The structure of a PG-1 film at the air-aqueous interface was also investigated by XR for the first time. Lipid A, dipalmitoyl-phosphatidylglycerol (DPPG) and dipalmitoyl-phosphatidylcholine (DPPC) monolayers were formed at the air-aqueous interface to mimic the surface of the bacterial cell wall and the outer leaflet of the erythrocyte cell membrane, respectively. Experiments were carried out under constant area conditions where the pressure changes upon insertion of peptide into the monolayer. GIXD data suggest that the greatest monolayer disruption produced by PG-1 is seen with the DPPG system at 20 mN/m since the Bragg peaks completely disappear after introduction of PG-1 to the system. PG-1 shows greater insertion into the lipid A system compared to the DPPC system when both films are held at the same initial surface pressure of 20 mN/m. The degree of insertion lessens at 30 mN/m with both DPPC and DPPG monolayer systems. XR data further reveal that PG-1 inserts primarily in the head group region of lipid monolayers. However, only the XR data of the anionic lipids suggest the existence of an additional adsorbed peptide layer below the head group of the monolayer. Overall the data show that the extent of peptide/lipid interaction and lipid monolayer disruption depends not only on the lipid composition of the monolayer, but the packing density of the lipids in the monolayer prior to the introduction of peptide to the subphase.
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Affiliation(s)
- Frances Neville
- Address, School of Process, Environmental and Materials Engineering, University of Leeds, Leeds, LS2 9JT, UK
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31
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Olak C, Muenter A, Andrä J, Brezesinski G. Interfacial properties and structural analysis of the antimicrobial peptide NK-2. J Pept Sci 2007; 14:510-7. [DOI: 10.1002/psc.954] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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32
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Petrov PG, Thompson JM, Rahman IBA, Ellis RE, Green EM, Miano F, Winlove CP. Two-dimensional order in mammalian pre-ocular tear film. Exp Eye Res 2007; 84:1140-6. [PMID: 17434484 DOI: 10.1016/j.exer.2007.02.012] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2006] [Revised: 02/05/2007] [Accepted: 02/15/2007] [Indexed: 11/26/2022]
Abstract
We report a grazing incidence x-ray diffraction (GIXD) investigation of the surface lipid layer of the pre-ocular tear film. For the first time we demonstrate the existence of 2D order over a wide range of surface pressures in this system, with typical spicing of 3.75A and 4.16A independent of the monolayer surface pressure. Analogous lipid ordering is also found in an artificial lipid mixture of the major lipid components of the tear film, suggesting that the 2D ordering is set by generic lipid-lipid interactions. Fluorescence microscopy of the natural and artificial tear film mixture reveals the co-existence of a dilute and a much more condensed phase in the amphiphilic lipid matrix over the pressure range of 15-45mN/m investigated by GIXD, plus an additional structure due to the much more hydrophobic part of the mixture. This evidence supports the previous hypothesis that tear film has a layered structure.
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33
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Noworyta K, Marczak R, Tylenda R, Sobczak JW, Chitta R, Kutner W, D'Souza F. "Two-point" assembling of Zn(II) and Co(II) metalloporphyrins derivatized with a crown ether substituent in Langmuir and Langmuir-Blodgett films. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2007; 23:2555-68. [PMID: 17309209 DOI: 10.1021/la0626858] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
The effect of "two-point" interactions of Zn(II) and Co(II) metalloporphyrins, bearing 15-crown-5 ether peripheral substituents, on their assembling in Langmuir and Langmuir-Blodgett (LB) films was investigated. That is, simultaneously, the central metal ion of the porphyrin was axially ligated by a nitrogen-containing ligand in the emerged part of the Langmuir film on one hand, and a suitably selected cation pertaining in the subphase solution was supramolecularly complexed by the crown ether moiety in the submerged part of the film on the other. The compression and polarity properties of the Langmuir films of the derivatized free-base 5,10,15-triphenyl-20-(benzo-15-crown-5)porphyrin, H2(TPMCP), and the corresponding cobalt(II) and zinc(II) metalloporphyrins, denoted as Co(TPMCP) and Zn(TPCMP), respectively, as well as inclusion complexes of the metalloporphyrins with selected cations were investigated. For the axial ligation of Zn(II) and Co(II), pyrazine (pyz) and 4,4'-bipyridnine (bpy) aromatic as well as piperazine (ppz) and 1,4-diazabicyclo[2.2.2]octane (DABCO) cyclic heteroaliphatic ligands were selected. The films were formed on the water subphase solution in the absence and presence of LiCl, NaCl, or NH4Cl. The Langmuir films were built of monolayer J-type aggregates of tilted porphyrin macrocycles. The porphyrins formed rather labile complexes with the cations in the subphase. Nevertheless, the XPS analysis revealed that these cations were LB transferred together with the porphyrins onto solid substrates. In the Co(TPMCP) Langmuir films formed on the water subphases, Co(II) was complexed by aromatic but not cyclic heteroaliphatic ligands, while, in these films formed on the NaCl subphase solutions, the metalloporphyrin was also complexed by DABCO. In Langmuir films spread on alkaline subphase solutions, both aromatic and heteroaliphatic ligands formed complexes with Co(TPMCP) of different stoichiometries. The X-ray reflectivity and GIXD measurements performed on selected LB films revealed some structure-building effects of the axial ligation.
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Affiliation(s)
- Krzysztof Noworyta
- Department of Mineral, Analytical and Applied Chemistry, University of Geneva, quai Ernest-Ansermet 30, CH-1211 Geneva, Switzerland
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34
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Neville F, Hodges CS, Liu C, Konovalov O, Gidalevitz D. In situ characterization of lipid A interaction with antimicrobial peptides using surface X-ray scattering. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2006; 1758:232-40. [PMID: 16584708 DOI: 10.1016/j.bbamem.2006.01.025] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/15/2005] [Revised: 01/29/2006] [Accepted: 01/31/2006] [Indexed: 11/23/2022]
Abstract
Lipid A structure at the air-aqueous interface has been studied using pressure-area isotherm methods coupled with the surface X-ray scattering techniques of X-ray reflectivity (XR) and grazing incidence X-ray diffraction (GIXD). Lipid A monolayers were formed at the air-aqueous interface to represent the lipid moiety of the outer membrane of Gram-negative bacteria. Lipid A structure was characterized at surface pressures between 10 and 35 mN/m. Interactions of alpha-helical antimicrobial peptides LL-37, SMAP-29 and D2A22 with lipid A monolayers were subsequently studied. Although insertion into the lipid A monolayers was observed with the alpha-helical peptides, little change was seen from the X-ray data, suggesting that the lipid A hydrocarbon chains are involved in reorientation during insertion and that the hydrocarbon chains have a relatively rigid structure.
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Affiliation(s)
- Frances Neville
- School of Process, Environmental and Materials Engineering, University of Leeds, Leeds LS2 9JT, UK
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35
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Neville F, Cahuzac M, Konovalov O, Ishitsuka Y, Lee KYC, Kuzmenko I, Kale GM, Gidalevitz D. Lipid headgroup discrimination by antimicrobial peptide LL-37: insight into mechanism of action. Biophys J 2006; 90:1275-87. [PMID: 16299073 PMCID: PMC1367279 DOI: 10.1529/biophysj.105.067595] [Citation(s) in RCA: 129] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2005] [Accepted: 09/29/2005] [Indexed: 11/18/2022] Open
Abstract
Interaction of the human antimicrobial peptide LL-37 with lipid monolayers has been investigated by a range of complementary techniques including pressure-area isotherms, insertion assay, epifluorescence microscopy, and synchrotron x-ray scattering, to analyze its mechanism of action. Lipid monolayers were formed at the air-liquid interface to mimic the surface of the bacterial cell wall and the outer leaflet of erythrocyte cell membrane by using phosphatidylglycerol (DPPG), phosphatidylcholine (DPPC), and phosphatidylethanolamine (DPPE) lipids. LL-37 is found to readily insert into DPPG monolayers, disrupting their structure and thus indicating bactericidal action. In contrast, DPPC and DPPE monolayers remained virtually unaffected by LL-37, demonstrating its nonhemolytic activity and lipid discrimination. Specular x-ray reflectivity data yielded considerable differences in layer thickness and electron-density profile after addition of the peptide to DPPG monolayers, but little change was seen after peptide injection when probing monolayers composed of DPPC and DPPE. Grazing incidence x-ray diffraction demonstrated significant peptide insertion and lateral packing order disruption of the DPPG monolayer by LL-37 insertion. Epifluorescence microscopy data support these findings.
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Affiliation(s)
- Frances Neville
- Institute for Materials Research, University of Leeds, Leeds, United Kingdom
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36
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Momsen WE, Mizuno NK, Lowe ME, Brockman HL. Real-time measurement of solute partitioning to lipid monolayers. Anal Biochem 2005; 346:139-49. [PMID: 16188221 DOI: 10.1016/j.ab.2005.08.009] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2005] [Revised: 08/05/2005] [Accepted: 08/09/2005] [Indexed: 11/15/2022]
Abstract
The interaction of a peripheral protein with a lipid-water interface can show a pronounced dependence on the composition and two-dimensional packing density of the lipids that comprise the interface. We report a novel optical method for measuring the adsorption of macromolecules, such as proteins and nucleic acids, and smaller solutes, such as drugs, to lipid monolayers at the gas-liquid interface. Using fluorescence emission from proteins and a small molecule, we demonstrate that the emissions from these solutes when in the aqueous phase and when associated with the monolayer can be temporally separated. Such separation allows measurement of the extent of solute adsorption, spectral characterization of the adsorbed solute, and characterization of lipid organization using adsorption kinetics. The method does not require, but is compatible with, the solute having different spectral properties in the bulk and surface phases. Indeed, if optical signals from adsorbed and soluble solute are the same or their relationship is known, absolute surface excess of adsorbed solute can be calculated without independent calibration. With appropriate instrumental configuration, the method should be adaptable for screening solutes for interaction with planar monolayers having both well-defined composition and adjustable lipid packing density.
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Affiliation(s)
- W E Momsen
- The Hormel Institute, University of Minnesota, Austin, MN 55912, USA
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37
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Wu G, Majewski J, Ege C, Kjaer K, Weygand MJ, Lee KYC. Interaction between lipid monolayers and poloxamer 188: an X-ray reflectivity and diffraction study. Biophys J 2005; 89:3159-73. [PMID: 16100276 PMCID: PMC1366812 DOI: 10.1529/biophysj.104.052290] [Citation(s) in RCA: 90] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The mechanism by which poloxamer 188 (P188) seals a damaged cell membrane is examined using the lipid monolayer as a model system. X-ray reflectivity and grazing-incidence x-ray diffraction results show that at low nominal lipid density, P188, by physically occupying the available area and phase separating from the lipids, forces the lipid molecules to pack tightly and restore the barrier function of the membrane. Upon compression to bilayer equivalent pressure, P188 is squeezed out from the lipid monolayer, allowing a graceful exit of P188 when the membrane integrity is restored.
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Affiliation(s)
- Guohui Wu
- Department of Chemistry, the Institute for Biophysical Dynamics and the James Franck Institute, the University of Chicago, 5735 S. Ellis Avenue, Chicago, IL 60637, USA
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38
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Justesen PH, Kristensen T, Ebdrup T, Otzen D. Investigating porcine pancreatic phospholipase A2 action on vesicles and supported planar bilayers using a quartz crystal microbalance with dissipation. J Colloid Interface Sci 2004; 279:399-409. [PMID: 15464804 DOI: 10.1016/j.jcis.2004.06.083] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2003] [Accepted: 06/27/2004] [Indexed: 11/15/2022]
Abstract
We present an investigation of the activity of porcine pancreatic phospholipase A2 towards phospholipids. The phospholipids are presented in three different ways, namely as tethered vesicles, intact surface-bound vesicles, and supported planar bilayers (SPBs). The process is followed using a quartz crystal microbalance which measures both the frequency shift and the energy dissipation factor. This technique is very sensitive not only to the mass of the material deposited on the crystal, but also to its viscoelasticity. The breakdown of the phospholipid vesicles and bilayers consequently gives rise to very large signal changes. Enzyme binding is separated from vesicle hydrolysis using nonhydrolyzable ether lipids. Intact and tethered vesicles give rise to the same profile, indicating that direct immobilization of the vesicles does not affect hydrolysis significantly. The data fit well to a Voight-based model describing the change in film structure with time. Initial enzyme binding to intact vesicles is accompanied by a significant increase in layer thickness as well as a decrease in viscosity and shear modulus. This effect, which is less pronounced in SPBs, is probably mainly due to the accumulation of hydrolysis products in the vesicle prior to rupture of the vesicles and release of bound water, since it disappears when lysolipid is included in the vesicles prior to hydrolysis.
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Affiliation(s)
- Pernille H Justesen
- Department of Life Sciences, Aalborg University, Sohngaardsholmsvej 49, DK-9000 Aalborg, Denmark
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Nielsen LK, Balashev K, Callisen TH, Bjørnholm T. Influence of product phase separation on phospholipase A(2) hydrolysis of supported phospholipid bilayers studied by force microscopy. Biophys J 2002; 83:2617-24. [PMID: 12414695 PMCID: PMC1302347 DOI: 10.1016/s0006-3495(02)75272-7] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022] Open
Abstract
In situ atomic force microscopy studies reveal a marked influence of the initial presence of hydrolysis products on the hydrolysis of supported phospholipid bilayers by phospholipase A(2). By analysis of the nano-scale topography of a number of supported bilayers with different initial product concentrations, made by Langmuir-Blodgett deposition, we show that small depressions enriched in products are efficiently promoting enzyme degradation of the bilayer. These small depressions, which are indicative of phase separation, are initially present in samples with 75% products. The kinetics of phospholipase A(2) exhibit under certain conditions an initial phase of slow hydrolysis, termed the latency phase, followed by a marked increase in the hydrolysis rate. The appearance of the phase-separated bilayer is strikingly similar to that of bilayers at the end of the latency phase. By analysis of individual nano-scale defects we illustrate a quantitative difference in the growth rates of defects caused by product aggregation and other structural defects. This difference shows for the first time how the enzyme prefers one type of defect to another.
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Affiliation(s)
- Lars K Nielsen
- Department of Chemistry, Technical University of Denmark, DK-2800 Lyngby, Denmark
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40
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Jensen MØ, Jensen TR, Kjaer K, Bjørnholm T, Mouritsen OG, Peters GH. Orientation and conformation of a lipase at an interface studied by molecular dynamics simulations. Biophys J 2002; 83:98-111. [PMID: 12080103 PMCID: PMC1302130 DOI: 10.1016/s0006-3495(02)75152-7] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Electron density profiles calculated from molecular dynamics trajectories are used to deduce the orientation and conformation of Thermomyces lanuginosa lipase and a mutant adsorbed at an air-water interface. It is demonstrated that the profiles display distinct fine structures, which uniquely characterize enzyme orientation and conformation. The density profiles are, on the nanosecond timescale, determined by the average enzyme conformation. We outline a computational scheme that from a single molecular dynamics trajectory allows for extraction of electron density profiles referring to different orientations of the lipase relative to an implicit interface. Profiles calculated for the inactive and active conformations of the lipase are compared with experimental electron density profiles measured by x-ray reflectivity for the lipase adsorbed at an air-water interface. The experimental profiles contain less fine structural information than the calculated profiles because the resolution of the experiment is limited by the intrinsic surface roughness of water. Least squares fits of the calculated profiles to the experimental profiles provide areas per adsorbed enzyme and suggest that Thermomyces lanuginosa lipase adsorbs to the air-water interface in a semiopen conformation with the lid oriented away from the interface.
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Affiliation(s)
- Morten Ø Jensen
- Center for Biomembrane Physics (MEMPHYS), Department of Chemistry, Technical University of Denmark, DK-2800 Lyngby, Denmark
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41
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Balashev K, Jensen TR, Kjaer K, Bjørnholm T. Novel methods for studying lipids and lipases and their mutual interaction at interfaces. Part I. Atomic force microscopy. Biochimie 2001; 83:387-97. [PMID: 11368846 DOI: 10.1016/s0300-9084(01)01264-0] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Mono-layers of lipids and their interaction with surface active enzymes (lipases) have been studied for more than a century. During the past decade new insight into this area has been obtained due to the development of scanning probe microscopy. This novel method provides direct microscopic information about the system in question and allows in situ investigations under near physiological conditions. In the present review the theory, experimental set-up and sample requirements of atomic force microscopy (AFM) are described. An overview of recent results is also presented with special emphasis on lipase hydrolysis and kinetics investigated in situ using AFM.
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Affiliation(s)
- K Balashev
- Department of Chemistry, University of Copenhagen, Universitetsparken 5, 2100, Copenhagen, Denmark
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42
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Jensen TR, Kjaer K. Structural Properties and Interactions of Thin Films at the Air-Liquid Interface Explored by Synchrotron X-Ray Scattering. STUDIES IN INTERFACE SCIENCE 2001. [DOI: 10.1016/s1383-7303(01)80028-4] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
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