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Marimuthu V, Chandirasekar S, Kasthuri J, Rajendiran N. Zwitterionic-Biosurfactant-Encapsulated Shape-Controlled AgNPs: An Assessment of Shape Effect on Catalytic Properties. ChemistrySelect 2018. [DOI: 10.1002/slct.201801370] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Affiliation(s)
- Vanitha Marimuthu
- Department of Polymer Science; University of Madras; Guindy Campus, Chennai-25; Tamil Nadu India
| | - Shanmugam Chandirasekar
- Department of Chemistry; Indian Institute of Technology-Madras (IIT−M), Chennai-36; Tamil Nadu India
| | - Jayapalan Kasthuri
- Department of Chemistry; Quaid-E- Millath Govt. College for Women, Chennai-2; Tamil Nadu
| | - Nagappan Rajendiran
- Department of Polymer Science; University of Madras; Guindy Campus, Chennai-25; Tamil Nadu India
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2
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Solubilization of the serotonin 1A receptor monitored utilizing membrane dipole potential. Chem Phys Lipids 2017; 209:54-60. [DOI: 10.1016/j.chemphyslip.2017.10.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2017] [Revised: 10/02/2017] [Accepted: 10/02/2017] [Indexed: 12/31/2022]
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3
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Chattopadhyay A, Rao BD, Jafurulla M. Solubilization of G Protein-Coupled Receptors. Methods Enzymol 2015; 557:117-34. [DOI: 10.1016/bs.mie.2015.01.001] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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4
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Dzyurkevich MS, Timofeeva KN, Faizullin DA, Zuev YF, Stoikov II, Plemenkov VV. Amphiphilic adducts of myrcene and N-substituted maleimides as potential drug delivery agents. MENDELEEV COMMUNICATIONS 2014. [DOI: 10.1016/j.mencom.2014.06.012] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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5
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Comparative study of the interaction of CHAPS and Triton X-100 with the erythrocyte membrane. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2013; 1838:859-66. [PMID: 24239862 DOI: 10.1016/j.bbamem.2013.11.006] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/17/2013] [Revised: 10/22/2013] [Accepted: 11/07/2013] [Indexed: 11/21/2022]
Abstract
The zwitterionic detergent CHAPS, a derivative of the bile salts, is widely used in membrane protein solubilization. It is a "facial" detergent, having a hydrophilic side and a hydrophobic back. The objective of this work is to characterize the interaction of CHAPS with a cell membrane. To this aim, erythrocytes were incubated with a wide range of detergent concentrations in order to determine CHAPS partition behavior, and its effects on membrane lipid order, hemolytic effects, and the solubilization of membrane phospholipids and cholesterol. The results were compared with those obtained with the nonionic detergent Triton X-100. It was found that CHAPS has a low affinity for the erythrocyte membrane (partition coefficient K=0.06mM(-1)), and at sub-hemolytic concentrations it causes little effect on membrane lipid order. CHAPS hemolysis and phospholipid solubilization are closely correlated. On the other side, binding of Triton X-100 disorders the membrane at all levels, and has independent mechanisms for hemolysis and solubilization. Differential behavior was observed in the solubilization of phospholipids and cholesterol. Thus, the detergent resistant membranes (DRM) obtained with the two detergents will have different composition. The behaviors of the two detergents are related to the differences in their molecular structures, suggesting that CHAPS does not penetrate the lipid bilayer but binds in a flat position on the erythrocyte surface, both in intact and cholesterol depleted erythrocytes. A relevant result for Triton X-100 is that hemolysis is not directly correlated with the solubilization of membrane lipids, as it is usually assumed.
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6
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Baranovic J, Ramanujan CS, Kasai N, Midgett CR, Madden DR, Torimitsu K, Ryan JF. Reconstitution of homomeric GluA2(flop) receptors in supported lipid membranes: functional and structural properties. J Biol Chem 2013; 288:8647-8657. [PMID: 23382380 DOI: 10.1074/jbc.m112.422105] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
AMPA receptors (AMPARs) are glutamate-gated ion channels ubiquitous in the vertebrate central nervous system, where they mediate fast excitatory neurotransmission and act as molecular determinants of memory formation and learning. Together with detailed analyses of individual AMPAR domains, structural studies of full-length AMPARs by electron microscopy and x-ray crystallography have provided important insights into channel assembly and function. However, the correlation between the structure and functional states of the channel remains ambiguous particularly because these functional states can be assessed only with the receptor bound within an intact lipid bilayer. To provide a basis for investigating AMPAR structure in a membrane environment, we developed an optimized reconstitution protocol using a receptor whose structure has previously been characterized by electron microscopy. Single-channel recordings of reconstituted homomeric GluA2(flop) receptors recapitulate key electrophysiological parameters of the channels expressed in native cellular membranes. Atomic force microscopy studies of the reconstituted samples provide high-resolution images of membrane-embedded full-length AMPARs at densities comparable to those in postsynaptic membranes. The data demonstrate the effect of protein density on conformational flexibility and dimensions of the receptors and provide the first structural characterization of functional membrane-embedded AMPARs, thus laying the foundation for correlated structure-function analyses of the predominant mediators of excitatory synaptic signals in the brain.
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Affiliation(s)
- Jelena Baranovic
- Department of Physics, University of Oxford, Oxford OX1 3PU, United Kingdom.
| | | | - Nahoko Kasai
- NTT Basic Research Laboratories, Atsugi, Kanagawa 243-0198, Japan
| | - Charles R Midgett
- Department of Biochemistry, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire 03755-1404
| | - Dean R Madden
- Department of Biochemistry, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire 03755-1404
| | | | - John F Ryan
- Department of Physics, University of Oxford, Oxford OX1 3PU, United Kingdom
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7
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Naskar B, Ghosh S, Nagadome S, Sugihara G, Moulik SP. Behavior of the amphiphile CHAPS alone and in combination with the biopolymer inulin in water and isopropanol-water media. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2011; 27:9148-9159. [PMID: 21667919 DOI: 10.1021/la201119c] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Self-aggregation of the zwitterionic surfactant 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonate (CHAPS) in water and isopropanol-water media, and interaction of the amphiphile with the biopolymer inulin in these media were investigated. The micellar properties of the zwitterionic surfactant and its associated interfacial and bulk properties along with the related energetic, and aggregation number were determined. The different stages of interaction of the CHAPS-inulin combines were identified and assessed. The complexes were formed and aggregated in solution at different stages of their molecular compositions. The aggregated sizes were determined by dynamic light scattering study and the morphology in the solvent removed states were examined using scanning electron microscope and transmission electron microscope techniques. The results witnessed formation of ensembles of varied and striking patterns.
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Affiliation(s)
- Bappaditya Naskar
- Centre for Surface Science, Department of Chemistry, Jadavpur University, Kolkata 700032, India
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8
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Merchán M, Velázquez M. Properties of CHAPS micelles modulated by different polyelectrolytes. Colloids Surf A Physicochem Eng Asp 2010. [DOI: 10.1016/j.colsurfa.2010.05.009] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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9
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Krylova OO, Jahnke N, Keller S. Membrane solubilisation and reconstitution by octylglucoside: comparison of synthetic lipid and natural lipid extract by isothermal titration calorimetry. Biophys Chem 2010; 150:105-11. [PMID: 20392557 DOI: 10.1016/j.bpc.2010.03.013] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2010] [Revised: 03/12/2010] [Accepted: 03/13/2010] [Indexed: 11/28/2022]
Abstract
We have studied the solubilisation and reconstitution of lipid membranes composed of either synthetic phosphatidylcholine or Escherichia. coli polar lipid extract by the non-ionic detergent octylglucoside. For both lipid systems, composition-dependent transformations of unilamellar vesicles into micelles or vice versa were followed by high-sensitivity isothermal titration calorimetry. Data obtained over a range of detergent and lipid concentrations could be rationalised in terms of a three-stage phase separation model involving bilayer, bilayer/micelle coexistence, and micellar ranges, yielding the detergent/lipid phase diagrams and the bilayer-to-micelle partition coefficients of both detergent and lipid. The most notable difference between the lipids investigated was a substantial widening of the bilayer/micelle coexistence range for E. coli lipid, which was due to an increased preference of the detergent and a decreased affinity of the lipid for the micellar phase as compared with the bilayer phase. These effects on the bilayer-to-micelle partition coefficients could be explained by the high proportion in E. coli membranes of lipids possessing negative spontaneous curvature, which hampers both their transfer into strongly curved micellar structures as well as the insertion of detergent into condensed bilayers.
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Affiliation(s)
- Oxana O Krylova
- Leibniz Institute of Molecular Pharmacology (FMP), Robert-Rössle-Str. 10, 13125 Berlin, Germany
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10
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Palladino P, Rossi F, Ragone R. Effective critical micellar concentration of a zwitterionic detergent: a fluorimetric study on n-dodecyl phosphocholine. J Fluoresc 2009; 20:191-6. [PMID: 19756982 DOI: 10.1007/s10895-009-0537-0] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2009] [Accepted: 08/25/2009] [Indexed: 11/27/2022]
Abstract
We have investigated the effect of ionic strength on the aggregation behavior of n-dodecyl phosphocholine. On the basis of the classical Corrin-Harkins relation, the critical micellar concentration of this detergent decreases with a biphasic trend on lithium chloride addition. It is nearly constant below 150 mM salt, with a mean value of 0.91 mM, whereas it undergoes a dramatic 80-fold decrease in 7 M LiCl. Such a drop in the critical micellar concentration could be explained by the effect of salting out and the implication of phosphocholine head groups on the organization of surrounding water. Knowledge of the effective critical micellar concentration of n-dodecyl phosphocholine could be useful in the purification of membrane proteins in non-denaturing conditions.
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Affiliation(s)
- Pasquale Palladino
- Dipartimento delle Scienze Biologiche & C.I.R.Pe.B., Università Federico II, via Mezzocannone 16, 80134, Naples, Italy
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11
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Abstract
Surfactants are surface-active, amphiphilic compounds that are water-soluble in the micro- to millimolar range, and self-assemble to form micelles or other aggregates above a critical concentration. This definition comprises synthetic detergents as well as amphiphilic peptides and lipopeptides, bile salts and many other compounds. This paper reviews the biophysics of the interactions of surfactants with membranes of insoluble, naturally occurring lipids. It discusses structural, thermodynamic and kinetic aspects of membrane-water partitioning, changes in membrane properties induced by surfactants, membrane solubilisation to micelles and other phases formed by lipid-surfactant systems. Each section defines and derives key parameters, mentions experimental methods for their measurement and compiles and discusses published data. Additionally, a brief overview is given of surfactant-like effects in biological systems, technical applications of surfactants that involve membrane interactions, and surfactant-based protocols to study biological membranes.
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12
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Beck A, Tsamaloukas AD, Jurcevic P, Heerklotz H. Additive action of two or more solutes on lipid membranes. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2008; 24:8833-8840. [PMID: 18646725 DOI: 10.1021/la800682q] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
A wide variety of biological processes, pharmaceutical applications, and technical procedures is based on the combined action of two or more soluble compounds to perturb, permeabilize, or lyse biological membranes. Here we present a general model describing the additive action of solutes on the properties of membranes or micelles. The onset and completion of membrane solubilization induced by two surfactants (lauryl maltoside, with nonyl maltoside, octyl glucoside, or CHAPS, respectively) are very well described by our model on the basis of their individual partition coefficients, cmc's, and critical mole ratios R e sat and R e sol as detected by isothermal titration calorimetry. This suggests that the thermodynamic phase transition is governed by a single parameter (e.g., spontaneous curvature) in spite of the complexity of structural changes. Such surfactant mixtures show unique features such as nonlinear solubilization boundaries and concentration-dependent effective partition coefficients. Other phenomena such as membrane leakage are predicted to obey additive action if the solutes act via the same mechanism (e.g., toroidal pore formation) but deviate from the model in the case of independent, synergistic, or antagonistic action.
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Affiliation(s)
- Andreas Beck
- Department of Biophysical Chemistry, Biozentrum of the University of Basel, Basel, Switzerland
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13
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Elmogy M, Iwami M, Sakurai S. Solubilization of the ecdysone binding protein from anterior silk gland cell membranes of the silkworm, Bombyx mori. Zoolog Sci 2008; 24:971-7. [PMID: 18088173 DOI: 10.2108/zsj.24.971] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2007] [Accepted: 05/20/2007] [Indexed: 11/17/2022]
Abstract
We previously provided preliminary evidence for the presence of a putative membrane ecdysone receptor (mEcR) anchored in the plasma membranes of anterior silk glands (ASGs) in Bombyx mori. This receptor may act in concert with the conventional EcR in 20E-dependent programmed cell death of these glands. We report here, for the first time, the solubilization of mEcR from ASG membranes using the zwitterionic detergent CHAPS in the presence of NaCl. Our results show by ligand binding assay that mEcR solubilized this way is functionally active and retains 75% of its native binding activity. We also defined experimental conditions that yielded protein/detergent complexes with partial binding activity, which makes it possible to purify the membrane-bound ecdysone binding protein.
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Affiliation(s)
- Mohamed Elmogy
- Division of Life Sciences, Graduate School of Science and Technology, Kanazawa University, Kakumamachi, Japan
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14
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Nath A, Grinkova YV, Sligar SG, Atkins WM. Ligand binding to cytochrome P450 3A4 in phospholipid bilayer nanodiscs: the effect of model membranes. J Biol Chem 2007; 282:28309-28320. [PMID: 17573349 DOI: 10.1074/jbc.m703568200] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The membrane-bound protein cytochrome P450 3A4 (CYP3A4) is a major drug-metabolizing enzyme. Most studies of ligand binding by CYP3A4 are currently carried out in solution, in the absence of a model membrane. Therefore, there is little information concerning the membrane effects on CYP3A4 ligand binding behavior. Phospholipid bilayer Nanodiscs are a novel model membrane system derived from high density lipoprotein particles, whose stability, monodispersity, and consistency are ensured by their self-assembly. We explore the energetics of four ligands (6-(p-toluidino)-2-naphthalenesulfonic acid (TNS), alpha-naphthoflavone (ANF), miconazole, and bromocriptine) binding to CYP3A4 incorporated into Nanodiscs. Ligand binding to Nanodiscs was monitored by a combination of environment-sensitive ligand fluorescence and ligand-induced shifts in the fluorescence of tryptophan residues present in the scaffold proteins of Nanodiscs; binding to the CYP3A4 active site was monitored by ligand-induced shifts in the heme Soret band absorbance. The dissociation constants for binding to the active site in CYP3A4-Nanodiscs were 4.0 microm for TNS, 5.8 microm for ANF, 0.45 microm for miconazole, and 0.45 microm for bromocriptine. These values are for CYP3A4 incorporated into a lipid bilayer and are therefore presumably more biologically relevant that those measured using CYP3A4 in solution. In some cases, affinity measurements using CYP3A4 in Nanodiscs differ significantly from solution values. We also studied the equilibrium between ligand binding to CYP3A4 and to the membrane. TNS showed no marked preference for either environment; ANF preferentially bound to the membrane, and miconazole and bromocriptine preferentially bound to the CYP3A4 active site.
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Affiliation(s)
- Abhinav Nath
- Department of Medicinal Chemistry, University of Washington, Seattle, Washington 98195
| | - Yelena V Grinkova
- Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801
| | - Stephen G Sligar
- Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801
| | - William M Atkins
- Department of Medicinal Chemistry, University of Washington, Seattle, Washington 98195.
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15
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Kalipatnapu S, Chattopadhyay A. Membrane Protein Solubilization: Recent Advances and Challenges in Solubilization of Serotonin1A Receptors. IUBMB Life 2005; 57:505-12. [PMID: 16081372 DOI: 10.1080/15216540500167237] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Solubilization of integral membrane proteins is a process in which the proteins and lipids that are held together in native membranes are suitably dissociated in a buffered detergent solution. The controlled dissociation of the membrane results in formation of small protein and lipid clusters that remain dissolved in the aqueous solution. Effective solubilization and purification of membrane proteins, especially heterologously-expressed proteins in mammalian cells in culture, in functionally active forms represent important steps in understanding structure-function relationship of membrane proteins. In this review, critical factors determining functional solubilization of membrane proteins are highlighted with the solubilization of the serotonin 1A receptor taken as a specific example.
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16
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Rouvinski A, Gahali-Sass I, Stav I, Metzer E, Atlan H, Taraboulos A. Both raft- and non-raft proteins associate with CHAPS-insoluble complexes: some APP in large complexes. Biochem Biophys Res Commun 2003; 308:750-8. [PMID: 12927782 DOI: 10.1016/s0006-291x(03)01470-0] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Components of caveolae and lipid rafts are characterized by their buoyancy after detergent extraction. Using flotations in density gradients, we now show that non-raft membrane molecules are also associated with detergent-insoluble, buoyant assemblies. When Triton X-100 cellular extracts were spun to equilibrium in Nycodenz, only components of classical rafts floated. In contrast, with the zwitterionic detergent CHAPS, non-raft residents such as calnexin and APP also buoyed. When CHAPS extracts were spun in non-equilibrium (velocity) conditions, some raft components rapidly exited the input fractions while other raft markers and non-raft molecules remained relatively immobile. This pointed to size heterogeneities of CHAPS-insoluble complexes. Combined velocity/equilibrium gradients broadly divided CHAPS-insoluble membrane complexes into three size categories, which all contained cholesterol and the glycosphingolipid GM1. Large complexes were enriched in caveolin and ESA. Medium size complexes were enriched in PrP, whereas small complexes contained non-raft proteins, PrP, and some ESA. While Alzheimer's APP was primarily confined to small assemblies, a portion of its glycosylated form did buoy with large complexes. Large CHAPS-insoluble complexes resemble, but are not equal to, classical rafts. These findings extend considerably the range of detergent-insoluble membranal domains.
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Affiliation(s)
- Alexander Rouvinski
- Department of Molecular Biology, The Hebrew University-Hadassah Medical School, P.O. Box 12272, Jerusalem 91120, Israel
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17
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Karlsson OP, Löfås S. Flow-mediated on-surface reconstitution of G-protein coupled receptors for applications in surface plasmon resonance biosensors. Anal Biochem 2002; 300:132-8. [PMID: 11779103 DOI: 10.1006/abio.2001.5428] [Citation(s) in RCA: 78] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
To facilitate biosensor studies of G-protein coupled receptors (GPCR) and other membrane proteins, reliable methods for preparation of sensor surfaces with high protein density are required. We present here a method for the easy and rapid immobilization and reconstitution of GPCR on carboxylated dextran surfaces modified with long alkyl groups. Following amine coupling of the detergent-solubilized receptor, lipid/detergent-mixed micelles were adhered as they were injected over the immobilized surface, taking advantage of the integrated flow cells. The detergent was eluted in the subsequent buffer flow and the remaining lipid formed a bilayer on the chip surface. With this procedure, rhodopsin was functionally reconstituted in a lipid environment in approximately 1 min. This method can also be used for the easy formation of pure supported lipid bilayers for use in model membrane interaction studies.
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Affiliation(s)
- Olof P Karlsson
- Department of Biochemistry and Chemistry, Biacore AB, Rapsgatan 7, SE-754 50 Uppsala, Sweden.
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18
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van Wachem PB, Brouwer LA, Zeeman R, Dijkstra PJ, Feijen J, Hendriks M, Cahalan PT, van Luyn MJ. Tissue reactions to epoxy-crosslinked porcine heart valves post-treated with detergents or a dicarboxylic acid. JOURNAL OF BIOMEDICAL MATERIALS RESEARCH 2001; 55:415-23. [PMID: 11255196 DOI: 10.1002/1097-4636(20010605)55:3<415::aid-jbm1031>3.0.co;2-x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Calcification limits the long-term durability of xenograft glutaraldehyde (GA)-crosslinked heart valves. Previously, a study in rats showed that epoxy-crosslinked heart valves reduced lymphocyte reactions to the same extent as the GA-crosslinked control and induced a similar foreign-body response and calcification reaction. The present study was aimed at reducing the occurrence of calcification of epoxy-crosslinked tissue. Two modifications were carried out and their influence on cellular reactions and the extent of calcification after 8 weeks' implantation in weanling rats was evaluated. First, epoxy-crosslinked valves were post-treated with two detergents to remove cellular elements, phospholipids and small soluble proteins, known to act as nucleation sites for calcification. The second approach was to study the effect of the impaired balance between negatively and positively charged amino acids by an additional crosslinking step with a dicarboxylic acid. The detergent treatment resulted in a washed-out appearance of especially the cusp tissue. With the dicarboxylic acid, both the cusps and the walls had a limited washed-out appearance. The wall also demonstrated some detachment of the subendothelium. After implantation, both detergent and dicarboxylic acid post-treatment histologically resulted in reduced calcification at the edges of cusps and walls. However, total amounts of calcification, measured by atomic emission spectroscopy, were not significantly reduced. Data concerning the presence of lymphocytes varied slightly, but were in the same range as the GA-crosslinked control, i.e., clearly reduced compared with a noncrosslinked control. It is concluded that both the double detergent and the dicarboxylic acid post-treatment of epoxy-crosslinked heart valve tissue do not represent a sound alternative in the fabrication of heart valve bioprostheses.
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Affiliation(s)
- P B van Wachem
- University of Groningen, Medical Biology, Tissue Engineering, University Hospital, Entrance 25, Hanzeplein 1, 9713 GZ Groningen, The Netherlands.
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19
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Kerkhoff C, Trümbach B, Gehring L, Habben K, Schmitz G, Kaever V. Solubilization, partial purification and photolabeling of the integral membrane protein lysophospholipid:acyl-CoA acyltransferase (LAT). EUROPEAN JOURNAL OF BIOCHEMISTRY 2000; 267:6339-45. [PMID: 11029575 DOI: 10.1046/j.1432-1327.2000.01724.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
In the present study, we defined experimental conditions that allowed the extraction of the integral membrane protein lysophospholipid:acyl-CoA acyltransferase (LAT, EC 2.3.1.23) from membranes while maintaining the full enzyme activity using the nonionic detergent n-octyl glucopyranoside (OGP) and solutions of high ionic strength. We found that the optimal OGP concentration depended on the ionic strength of the solubilization buffer. Fluorescence measurements with 1,6-diphenyl-1,3,5-hexatriene indicated that the critical micellar concentration (CMC) of OGP decreased with increasing salt concentrations. Analogous studies revealed that the zwitterionic detergent Chaps was ineffective in extracting LAT from membranes in the absence of salt, whereas its solubilization efficiency increased with increasing salt concentrations. Detailed lipid analysis of the different protein/lipid/detergent mixed micelles showed that the protein/lipid/OGP mixed micelles were relatively enriched with sphingomyelin (SPM) compared to protein/lipid/Chaps mixed micelles, indicating that the differences in the solubilization efficiency may be due to the ability to extract more SPM from membranes. When the protein/lipid/OGP mixed micelles were dissociated into protein/detergent and lipid/detergent complexes by the addition of increasing Chaps concentrations, one-tenth of the LAT enzyme activity was preserved making the enzyme accessible to protein purification. Analysis by native PAGE revealed that in the presence of excess Chaps a high molecular mass protein complex migrated into the gel which could be photolabeled by 125I-labelled-18-(4'-azido-2'-hydroxybenzoylamino)-oleyl-CoA. This fatty acid analogue has been shown to be a competitive inhibitor of LAT enzyme activity in the dark, and an irreversible inhibitor after photolysis. Therefore, this protein complex is assumed to contain the LAT enzyme.
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Affiliation(s)
- C Kerkhoff
- Institute of Pharmacology, Medical School Hannover, Germany
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20
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Obrdlik P, Neuhaus G, Merkle T. Plant heterotrimeric G protein beta subunit is associated with membranes via protein interactions involving coiled-coil formation. FEBS Lett 2000; 476:208-12. [PMID: 10913615 DOI: 10.1016/s0014-5793(00)01706-3] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Gbeta subunits from animals are anchored to membranes via Ggamma subunits. No Ggamma has been identified in plants to date. Using differential centrifugation of Arabidopsis and broccoli extracts, Gbeta was highly enriched in the microsomal pellet. Treatment of microsomes with detergents and salts indicates that plant Gbeta is located at the membrane surface and attached to membranes by hydrophobic interactions. Analysis of transgenic plants expressing Gbeta-GFP fusion proteins showed that mutations in the heptad repeat domain of Gbeta severely diminished their membrane association. We propose that plant Gbeta is anchored to membranes by an unknown protein similar to animal Gbeta by Ggamma, via coiled-coil formation.
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Affiliation(s)
- P Obrdlik
- Institut für Biologie II, Zellbiologie, Universität Freiburg, Schänzlestr. 1, D-79104, Freiburg, Germany
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21
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Vikström S, Li L, Karlsson OP, Wieslander A. Key role of the diglucosyldiacylglycerol synthase for the nonbilayer-bilayer lipid balance of Acholeplasma laidlawii membranes. Biochemistry 1999; 38:5511-20. [PMID: 10220338 DOI: 10.1021/bi982532m] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
In the single membrane of Acholeplasma laidlawii, a specific glucosyltransferase (DGlcDAG synthase) synthesizes the major, bilayer-forming lipid diglucosyldiacylglycerol (DGlcDAG) from the preceding major, nonbilayer-prone monoglucosyldiacylglycerol (MGlcDAG). This is crucial for the maintenance of phase equilibria close to a potential bilayer-nonbilayer transition and a nearly constant spontaneous curvature for the membrane bilayer lipid mixture. The glucolipid pathway is also balanced against the phosphatidylglycerol (PG) pathway to maintain a certain lipid surface charge density. The DGlcDAG synthase was purified approximately 5000-fold by three chromatographic techniques and identified as a minor 40 kDa membrane protein. In CHAPS mixed micelles, a cooperative dependence on anionic lipid activators was confirmed, with PG as the best. The dependence of the enzyme on the soluble UDP-glucose substrate followed Michaelis-Menten kinetics, while the kinetics for the other (lipid) substrate MGlcDAG exhibited cooperativity, with Hill coefficients in the range of 3-5. Vmax and the Hill coefficient, but not Km, for the MGlcDAG substrate were increased by increased PG concentrations, but above 3 mol % MGlcDAG, the rate of synthesis was constant. Hence, the DGlcDAG synthase is more affected by the lipid activator than by the lipid substrate at physiological lipid concentrations. The enzyme was shown to be sensitive to curvature "stress" changes, i.e., was stimulated by various nonbilayer lipids but inhibited by certain others. Certain phosphates were also stimulatory. With the two purified MGlcDAG and DGlcDAG synthases reconstituted together in the presence of a potent nonbilayer lipid, the strong responses in the amounts of MGlcDAG and DGlcDAG synthesized mimicked the responses in vivo. This supports the important regulatory functions of these enzymes.
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Affiliation(s)
- S Vikström
- Department of Biochemistry, Umeå University, Sweden.
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Thermodynamics and Kinetics of Spontaneous Formation and Breakdown of Vesicles in Aqueous Media**We are delighted to dedicate this article to our mentor, John Albery. ACTA ACUST UNITED AC 1999. [DOI: 10.1016/s0069-8040(99)80024-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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Uebel S, Plantinga T, Weber PJ, Beck-Sickinger AG, Tampé R. Peptide binding and photo-crosslinking to detergent solubilized and to reconstituted transporter associated with antigen processing (TAP). FEBS Lett 1997; 416:359-63. [PMID: 9373185 DOI: 10.1016/s0014-5793(97)01222-2] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The transporter associated with antigen processing (TAP) is essential for peptide loading onto major histocompatibility (MHC) class I molecules by translocating peptides into the endoplasmic reticulum. We have explored the conditions for detergent solubilization of functionally active, heterologously expressed human TAP from microsomal membranes. The efficiency to solubilize TAP was tested for a variety of detergents as well as for different solubilization conditions. The activity of the solubilized TAP complex was analyzed over time, using a non-radioactive crosslinking assay with a photo-activateable peptide, in the presence or absence of external lipid. The detergent CHAPS was found optimally to retain activity and thus allowed us to reconstitute detergent-solubilized, active TAP into proteoliposomes.
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Affiliation(s)
- S Uebel
- Max-Planck-Institut für Biochemie, Martinsried, Germany
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Karlsson OP, Dahlqvist A, Vikström S, Wieslander A. Lipid dependence and basic kinetics of the purified 1,2-diacylglycerol 3-glucosyltransferase from membranes of Acholeplasma laidlawii. J Biol Chem 1997; 272:929-36. [PMID: 8995384 DOI: 10.1074/jbc.272.2.929] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
UDP-glucose: 1,2-diacylglycerol 3-glucosyltransferase (EC 2.4.1.157), catalyzes the transfer of glucose from UDP-glucose to diacylglycerol (DAG) to yield monoglucosyldiacylglycerol (MGlcDAG) and UDP. MGlcDAG is the first glucolipid along the glucolipid pathway, and a major (nonbilayer-prone) lipid in the single membrane of Acholeplasma laidlawii. MGlcDAG is further glucosylated to give the major diglucosyldiacylglycerol (DGlc-DAG). The bilayer fractions of these lipids are crucial for the metabolic maintenance of phase equilibria close to a potential bilayer-nonbilayer transition and a nearly constant spontaneous curvature. The glucolipid syntheses are also balanced against the phosphatidylglycerol pathway, competing for the common minor precursor phosphatidic acid, to retain a constant lipid surface charge density. The 1,2-diacylglycerol 3-glucosyltransferase was purified to homogeneity from detergent-solubilized A. laidlawii cells by three column chromatography methods (enrichment approximately 9000 x), and identified as a minor 40-kDa protein by using SDS-polyacrylamide gel electrophoresis. In CHAPS detergent, mixed micelles, a cooperative dependence on anionic lipids for activity was confirmed. Dependence of the enzyme on UDP-glucose followed Michaelis-Menten kinetics while the other hydrophobic substrate dioleoylglycerol stimulated the enzyme by an activating, potentially cooperative mechanism. Physiological concentrations of the activator lipid dioleoyl-phosphatidylglycerol influenced the turnover number of the enzyme but not the interaction with UDP-glucose, as inferred from variable and constant values of the apparent Vmax and Km, respectively. Dipalmitoylglycerol was a better substrate than the oleoyl species, supporting earlier in vivo and crude enzyme data. The responses of the purified 1,2-diacylglycerol 3-glucosyltransferase indicated that (i) the regulatory features of the MGlcDAG synthesis is held by the catalytic enzyme itself, and (ii) this strongly corroborates the "homeostasis" model for lipid bilayer properties in A. laidlawii proposed earlier.
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Affiliation(s)
- O P Karlsson
- Department of Biochemistry, Umeå University, Sweden.
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Chattopadhyay A, Harikumar KG. Dependence of critical micelle concentration of a zwitterionic detergent on ionic strength: implications in receptor solubilization. FEBS Lett 1996; 391:199-202. [PMID: 8706916 DOI: 10.1016/0014-5793(96)00733-8] [Citation(s) in RCA: 98] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
The zwitterionic detergent, 3-[(3-cholamidopropyl)-dimethylammonio]-1-propanesulfonate (CHAPS), is mild, non-denaturing, and extensively used for solubilizing membrane proteins and receptors. We report here that the critical micelle concentration (CMC) of CHAPS is dependent on the concentration of NaCl in the solution. Thus, the CMC of CHAPS decreases from 6.41 mM in absence of any salt to 4.10 mM in presence of 1.5 M NaCl. The logarithm of the CMC values appear to have a linear relationship with the salt concentration. Such changes in CMC with ionic strength have important implications in solubilization of membrane-bound neuronal receptors. This is shown by optimal solubilization of the serotonin receptor type 1A (5-HT1A) from bovine brain hippocampal crude (native) membrane by CHAPS at premicellar concentration under high salt conditions.
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Affiliation(s)
- A Chattopadhyay
- Centre for Cellular and Molecular Biology, Hyderabad, India.
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Packwood L, Taylor E, Storey TM, Evans-Gowing R, Baillie-Johnson H, Warn RM. Large vesicle formation within cells induced by treatment with a mixed surfactant. Micron 1996; 27:95-105. [PMID: 8858866 DOI: 10.1016/0968-4328(96)00019-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
MDCK cells have been treated with a mixed surfactant at low concentrations to study the induced morphological changes. The most significant change at the light microscope level was the appearance of multiple large vesicles, which increased in size with time, up to approximately 40 microns in diameter. Vesicle formation was shown to be linked with the uptake of the fluid medium, as judged by the presence of FITC-dextran within the vesicles, but was not a result of pinocytosis because cytochalasin D treatment had no effect on their formation. Furthermore, nile red staining demonstrated that the vesicles did not represent fusion of pre-existing lipid droplets. Transmission electron microscopy (TEM) analysis indicated that the vesicles lacked any obvious structure. It is hypothesised that the vesicles are large mixed structures synthesised as a result of interactions between cell membranes and detergent components after saturation with the surfactants. This effect is contrasted with the diffuse uptake of dyes and fluorescently labelled proteins following simple anionic or ionic detergent treatment. The effect of vesicle formation was reversible if the cells were placed in fresh medium lacking detergent. Other effects of mixed detergent included the loss of rounded compact colonies, an increase in mean cell diameter and the almost complete loss of surface microvilli as seen with scanning electron microscopy (SEM). In the TEM the cell ultrastructure was seen to have changed markedly following detergent treatment, with a loss of rough endoplasmic reticulum and an apparent clumping of the cytoplasmic constituents.
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Affiliation(s)
- L Packwood
- School of Biology, University of East Anglia, Norwich, U.K
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