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Dietel L, Kalie L, Heerklotz H. Lipid Scrambling Induced by Membrane-Active Substances. Biophys J 2020; 119:767-779. [PMID: 32738218 DOI: 10.1016/j.bpj.2020.07.004] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2020] [Revised: 07/03/2020] [Accepted: 07/07/2020] [Indexed: 11/26/2022] Open
Abstract
The functional roles of the lipid asymmetry of biomembranes are attracting increasing attention. This study characterizes the activity of surfactants to induce transmembrane flip-flop of lipids and thus "scramble" this asymmetry. Detergent-induced lipid scrambling of liposomes mimicking the charge asymmetry of bacterial membranes with 20 mol % of 1-palmitoyl-2-oleoyl-sn-glycero-3-phospho-rac-glycerol in the outer leaflet only was quantified by ζ-potential measurements for octaethylene glycol dodecyl ether (C12EO8), octyl glucoside (OG), and dodecyl maltoside. Membrane leakage was separately measured by the fluorescence lifetime-based calcein leakage assay and the onset of the membrane-to-micelle transition by isothermal titration calorimetry. Partition coefficients and partial molar areas were obtained as well. For the quickly membrane-permeant C12EO8 and OG, leakage proceeds at a rather sharp threshold content in the membrane, which is well below the onset of solubilization and little dependent on incubation time; it is accompanied by fast lipid scrambling. However, unlike leakage, flip-flop is a relaxation process that speeds up gradually from taking weeks in the detergent-free membrane to minutes or less in the leaking membrane. Hence, after 24 h of incubation, 10 mol % of C12EO8 or 50 mol % of OG in the membrane suffice for virtually complete lipid scrambling, whereas leakage remains below 10% for up to 14 mol % of C12EO8 and 88 mol % of OG. There is thus a concentration window in which lipid scrambling proceeds without leakage. This implies that lipid scrambling must be considered a possible mode of action of antimicrobial peptides and other membrane-active drugs or biomolecules. A related, detergent-based protocol for scrambling the lipid asymmetry of liposomes and maybe cells without compromising their overall integrity would be a very valuable tool to study functions of lipid asymmetry.
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Affiliation(s)
- Lisa Dietel
- Institute of Pharmaceutical Sciences, University of Freiburg, Freiburg, Germany.
| | - Louma Kalie
- Institute of Pharmaceutical Sciences, University of Freiburg, Freiburg, Germany
| | - Heiko Heerklotz
- Institute of Pharmaceutical Sciences, University of Freiburg, Freiburg, Germany; Signaling Research Centers BIOSS and CIBSS, University of Freiburg, Freiburg, Germany; Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto, Ontario, Canada.
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2
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Akhmedov AA, Shurpik DN, Plemenkov VV, Stoikov II. Water-soluble meroterpenes containing an aminoglyceride fragment with geraniol residues: synthesis and membranotropic properties. MENDELEEV COMMUNICATIONS 2019. [DOI: 10.1016/j.mencom.2019.01.008] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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3
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Chen Y, Qiao F, Fan Y, Han Y, Wang Y. Interactions of Phospholipid Vesicles with Cationic and Anionic Oligomeric Surfactants. J Phys Chem B 2017; 121:7122-7132. [PMID: 28686026 DOI: 10.1021/acs.jpcb.7b05297] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
This work studied the interactions of 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) with cationic ammonium surfactants and anionic sulfate or sulfonate surfactants of different oligomeric degrees, including cationic monomeric DTAB, dimeric C12C3C12Br2, and trimeric DDAD as well as anionic monomeric SDS, dimeric C12C3C12(SO3)2, and trimeric TED-(C10SO3Na)3. The partition coefficient P of these surfactants between the DOPC vesicles and water was determined with isothermal titration microcalorimetry (ITC) by titrating concentrated DOPC solution into the monomer solution of these surfactants. It was found that the P value increases with the increase of the surfactant oligomeric degree. Moreover, the enthalpy change and the Gibbs free energy for the transition of these surfactants from water into the DOPC bilayer become more negative with increasing the oligomeric degree. Meanwhile, the calcein release experiment proves that the surfactant with a higher oligomeric degree shows stronger ability of changing the permeability of the DOPC vesicles. Furthermore, the solubilization of the DOPC vesicles by these oligomeric surfactants was studied by ITC, turbidity, and dynamic light scattering, and thus the phase boundaries for the surfactant/lipid mixtures have been determined. The critical surfactant to lipid ratios for the onset and end of the solubilization for the DOPC vesicles derived from the phase boundaries decrease remarkably with increasing the oligomeric degree. Overall, the surfactant with a larger oligomerization degree shows stronger ability in incorporating into the lipid bilayer, altering the membrane permeability and solubilizing lipid vesicles, which provides comprehensive understanding about the effects of structure and shape of oligomeric surfactant molecules on lipid-surfactant interactions.
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Affiliation(s)
- Yao Chen
- Key Laboratory of Colloid and Interface Science, Beijing National Laboratory for Molecular Sciences (BNLMS), CAS Research/Education Center for Excellence in Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences , Beijing 100190, P. R. China.,University of Chinese Academy of Sciences , Beijing 100049, P. R. China
| | - Fulin Qiao
- Key Laboratory of Colloid and Interface Science, Beijing National Laboratory for Molecular Sciences (BNLMS), CAS Research/Education Center for Excellence in Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences , Beijing 100190, P. R. China.,University of Chinese Academy of Sciences , Beijing 100049, P. R. China
| | - Yaxun Fan
- Key Laboratory of Colloid and Interface Science, Beijing National Laboratory for Molecular Sciences (BNLMS), CAS Research/Education Center for Excellence in Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences , Beijing 100190, P. R. China
| | - Yuchun Han
- Key Laboratory of Colloid and Interface Science, Beijing National Laboratory for Molecular Sciences (BNLMS), CAS Research/Education Center for Excellence in Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences , Beijing 100190, P. R. China
| | - Yilin Wang
- Key Laboratory of Colloid and Interface Science, Beijing National Laboratory for Molecular Sciences (BNLMS), CAS Research/Education Center for Excellence in Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences , Beijing 100190, P. R. China.,University of Chinese Academy of Sciences , Beijing 100049, P. R. China
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4
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Faizullin DA, Dzyurkevich MS, Valiullina YA, Islamov DR, Kataeva ON, Zuev YF, Plemenkov VV, Stoikov II. Novel type of isoprenoid membrane anchors: an investigation of binding properties with dipalmitoylphosphatidylcholine vesicles. J PHYS ORG CHEM 2017. [DOI: 10.1002/poc.3618] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Dzhigangir A. Faizullin
- Kazan Institute of Biochemistry and Biophysics; Russian Academy of Sciences; Kazan Russia
- Alexander Butlerov Institute of Chemistry; Kazan Federal University; Kazan Russia
| | | | - Yuliya A. Valiullina
- Kazan Institute of Biochemistry and Biophysics; Russian Academy of Sciences; Kazan Russia
| | - Daut R. Islamov
- Alexander Butlerov Institute of Chemistry; Kazan Federal University; Kazan Russia
| | - Olga N. Kataeva
- A.E. Arbuzov Institute of Organic and Physical Chemistry; Russian Academy of Sciences; Kazan Russia
| | - Yuriy F. Zuev
- Kazan Institute of Biochemistry and Biophysics; Russian Academy of Sciences; Kazan Russia
- Alexander Butlerov Institute of Chemistry; Kazan Federal University; Kazan Russia
| | - Vitaliy V. Plemenkov
- Institute of Biochemistry; Immanuel Kant Baltic Federal University; Kaliningrad Russia
| | - Ivan I. Stoikov
- Alexander Butlerov Institute of Chemistry; Kazan Federal University; Kazan Russia
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5
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Chen Y, Qiao F, Fan Y, Han Y, Wang Y. Interactions of Cationic/Anionic Mixed Surfactant Aggregates with Phospholipid Vesicles and Their Skin Penetration Ability. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2017; 33:2760-2769. [PMID: 28013540 DOI: 10.1021/acs.langmuir.6b04093] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
This work studied the interactions of an oppositely charged surfactant mixture of oleyl bis(2-hydroxyethyl)methyl ammonium bromide (OHAB) and sodium dodecyl sulfate (SDS) with 1,2-di-(9Z-octadecenoyl)-sn-glycero-3-phosphocholine (DOPC) vesicles as well as the penetration of the OHAB/SDS mixture through model skin, aimed at understanding the relationship between the ability of different surfactant aggregates in solubilizing phospholipid vesicles and their potential in irritating skin. By changing the molar fraction of OHAB (XOHAB), five kinds of aggregates are constructed: OHAB and SDS separately form cationic and anionic small micelles, whereas the OHAB/SDS mixtures form cationic and anionic vesicles at XOHAB = 0.30 and 0.70, respectively, and weakly charged vesicles at XOHAB = 0.50. The mixtures have much lower critical micellar concentrations (CMCs) and much larger aggregates than either OHAB or SDS alone, and the CMC and the size of the OHAB/SDS vesicles decrease with the increase in XOHAB. The phase diagrams indicate that the OHAB/SDS mixtures show much stronger ability in solubilizing the DOPC vesicles than individual OHAB and SDS and decrease in the order of XOHAB = 0.30 > 0.50 > 0.70 ≫ 1.00 > 0. However, the ability of the surfactants in penetrating the model skin decreases reversely, and the penetration of the surfactants are significantly reduced by mixing. These results indicate that the surfactant mixture with a larger aggregate size and a smaller CMC value displays much stronger ability in solubilizing the DOPC vesicles but much weaker ability in penetrating the skin.
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Affiliation(s)
- Yao Chen
- Key Laboratory of Colloid and Interface Science, Beijing National Laboratory for Molecular Sciences (BNLMS), Institute of Chemistry, Chinese Academy of Sciences , Beijing 100190, P. R. China
- University of Chinese Academy of Sciences , Beijing 100049, P. R. China
| | - Fulin Qiao
- Key Laboratory of Colloid and Interface Science, Beijing National Laboratory for Molecular Sciences (BNLMS), Institute of Chemistry, Chinese Academy of Sciences , Beijing 100190, P. R. China
- University of Chinese Academy of Sciences , Beijing 100049, P. R. China
| | - Yaxun Fan
- Key Laboratory of Colloid and Interface Science, Beijing National Laboratory for Molecular Sciences (BNLMS), Institute of Chemistry, Chinese Academy of Sciences , Beijing 100190, P. R. China
| | - Yuchun Han
- Key Laboratory of Colloid and Interface Science, Beijing National Laboratory for Molecular Sciences (BNLMS), Institute of Chemistry, Chinese Academy of Sciences , Beijing 100190, P. R. China
| | - Yilin Wang
- Key Laboratory of Colloid and Interface Science, Beijing National Laboratory for Molecular Sciences (BNLMS), Institute of Chemistry, Chinese Academy of Sciences , Beijing 100190, P. R. China
- University of Chinese Academy of Sciences , Beijing 100049, P. R. China
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6
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Fan HY, Das D, Heerklotz H. "Staying Out" Rather than "Cracking In": Asymmetric Membrane Insertion of 12:0 Lysophosphocholine. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2016; 32:11655-11663. [PMID: 27715063 DOI: 10.1021/acs.langmuir.6b03292] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Interactions between detergents and model membranes are well described by the three-stage model: saturation and solubilization boundaries divide bilayer-only, bilayer-micelle coexistence, and micelle-only ranges. An underlying assumption of the model is the equilibration of detergent between the two membrane leaflets. However, many detergents partition asymmetrically at room temperature due to slow flip-flop, such as sodium dodecyl sulfate (SDS) and lysolipids. In this work, we use isothermal titration calorimetry (ITC) and dynamic light scattering (DLS) to investigate the solubilization of unilamellar POPC vesicles by 12:0 lysophosphocholine (12:0 LPC). Flip-flop of 12:0 LPC occurs beyond the time scale of our experiments, which establish a characteristic nonequilibrated state with asymmetric distribution: 12:0 LPC partitions primarily into the outer leaflet. Increasing asymmetry stress in the membrane does not lead to membrane failure, i.e., "cracking in" as seen for alkyl maltosides and other surfactants; instead, it reduces further membrane insertion which leads to the "staying out" of 12:0 LPC in solution. At above the critical micellar concentration of 12:0 LPC in the presence of the membrane, micelles persist and accommodate further LPC but take up lipid from vesicles only very slowly. Ultimately, solubilization proceeds via the micellar mechanism (Kragh-Hansen et al., 1995). With a combination of demicellization and solubilization experiments, we quantify the molar ratio partition coefficient (0.6 ± 0.1 mM-1) and enthalpy of partitioning (6.1 ± 0.3 kJ·mol-1) and estimate the maximum detergent/lipid ratio reached in the outer leaflet (<0.13). Despite the inapplicability of the three-stage model to 12:0 LPC at room temperature, we are able to extract quantitative information from ITC solubilization experiments and DLS that are important for the understanding of asymmetry-dependent processes such as endocytosis and the gating of mechanosensitive channels in vitro.
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Affiliation(s)
- Helen Y Fan
- Leslie Dan Faculty of Pharmacy, University of Toronto , Toronto, Ontario, Canada
| | - Dew Das
- Leslie Dan Faculty of Pharmacy, University of Toronto , Toronto, Ontario, Canada
| | - Heiko Heerklotz
- Leslie Dan Faculty of Pharmacy, University of Toronto , Toronto, Ontario, Canada
- Institute for Pharmaceutical Sciences, University of Freiburg , Freiburg, Germany
- BIOSS Centre for Biological Signalling Studies , Freiburg, Germany
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7
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Khimani M, Rao U, Bahadur P, Bahadur P. Calorimetric and Scattering Studies on Micellization of Pluronics in Aqueous Solutions: Effect of the Size of Hydrophilic PEO End Blocks, Temperature, and Added Salt. J DISPER SCI TECHNOL 2014. [DOI: 10.1080/01932691.2013.858349] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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8
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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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9
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Thanassoulas A, Barthélémy P, Navailles L, Sigaud G. From nucleobases to nucleolipids: an ITC approach on the thermodynamics of their interactions in aqueous solutions. J Phys Chem B 2014; 118:6570-85. [PMID: 24911942 DOI: 10.1021/jp411459w] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Hybrid constructions based on nucleosides and lipophilic components, known as nucleolipids, have become an extremely interesting class of molecules, especially for their potential biomedical applications. In this matter, it seemed important to define the nature and estimate the strength of their interaction with polynucleotides by different ways. We report in this work a systematic investigation through isothermal titration calorimetry of the thermodynamics of the association and dissociation of adenine and thymine derivatives, not previously performed. Then we use the results obtained on these simple systems as a basis for comparison with the binding of phospholipids functionalized with adenosine and thymidine to polyadenylic or polyuridylic acids applying the same experimental technique.
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10
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Murray D, Griffin J, Cross TA. Detergent optimized membrane protein reconstitution in liposomes for solid state NMR. Biochemistry 2014; 53:2454-63. [PMID: 24665863 PMCID: PMC4004220 DOI: 10.1021/bi500144h] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2014] [Revised: 03/24/2014] [Indexed: 12/18/2022]
Abstract
For small helical membrane proteins, their structures are highly sensitive to their environment, and solid state NMR is a structural technique that can characterize these membrane proteins in native-like lipid bilayers and proteoliposomes. To date, a systematic method by which to evaluate the effect of the solubilizing detergent on proteoliposome preparations for solid state NMR of membrane proteins has not been presented in the literature. A set of experiments are presented aimed at determining the conditions most amenable to dialysis mediated reconstitution sample preparation. A membrane protein from M. tuberculosis is used to illustrate the method. The results show that a detergent that stabilizes the most protein is not always ideal and sometimes cannot be removed by dialysis. By focusing on the lipid and protein binding properties of the detergent, proteoliposome preparations can be readily produced, which provide double the signal-to-noise ratios for both the oriented sample and magic angle spinning solid state NMR. The method will allow more membrane protein drug targets to be structurally characterized in lipid bilayer environments.
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Affiliation(s)
- Dylan
T. Murray
- Institute
for Molecular Biophysics, Florida State
University, 91 Chieftan
Way, Tallahassee, Florida 32306, United States
- The
National High Magnetic Field Laboratory, 1800 E. Paul Dirac Dr., Tallahassee, Florida 32310, United States
| | - James Griffin
- The
National High Magnetic Field Laboratory, 1800 E. Paul Dirac Dr., Tallahassee, Florida 32310, United States
- Department
of Chemistry and Biochemistry, Florida State
University, 95 Chieftan
Way, Tallahassee, Florida 32306, United States
| | - Timothy A. Cross
- Institute
for Molecular Biophysics, Florida State
University, 91 Chieftan
Way, Tallahassee, Florida 32306, United States
- The
National High Magnetic Field Laboratory, 1800 E. Paul Dirac Dr., Tallahassee, Florida 32310, United States
- Department
of Chemistry and Biochemistry, Florida State
University, 95 Chieftan
Way, Tallahassee, Florida 32306, United States
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11
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Kiselev M, Janich M, Hildebrand A, Strunz P, Neubert R, Lombardo D. Structural transition in aqueous lipid/bile salt [DPPC/NaDC] supramolecular aggregates: SANS and DLS study. Chem Phys 2013. [DOI: 10.1016/j.chemphys.2013.05.014] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
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12
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Aberg C, Sparr E, Wennerström H. Lipid phase behaviour under steady state conditions. Faraday Discuss 2013; 161:151-66; discussion 273-303. [PMID: 23805741 DOI: 10.1039/c2fd20079a] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
At the interface between two regions, for example the air-liquid interface of a lipid solution, there can arise non-equilibrium situations. The water chemical potential corresponding to the ambient RH will, in general, not match the water chemical potential of the solution, and the gradients in chemical potential cause diffusional flows. If the bulk water chemical potential is close to a phase transition, there is the possibility of forming an interfacial phase with structures qualitatively different from those found in the bulk. Based on a previous analysis of this phenomenon in two component systems (C. Aberg, E. Sparr, K. J. Edler and H. Wennerström, Langmuir, 2009, 25, 12177), we here analyse the henomenon for three-component systems. The relevant transport equations are erived, and explicit results are given for some limiting cases. Then the formalism s applied conceptually to four different aqueous lipid systems, which in addition to water and a phospholipid contain (i) octyl glucoside, (ii) urea, (iii) heavy water, and (iv) sodium cholate as the third component. These four cases are chosen to illustrate (i) a method to use a micelle former to transport lipid to the interface where a multi-lamellar structure can form; (ii) to use a co-solvent to inhibit the formation of a gel phase at the interface; (iii) a method to form pure phospholipid multi-lamellar structures at the interface; (iv) a method to form a sequence of phases in the interfacial region. These four cases all have the character of theoretically based conjectures and it remains to investigate experimentally whether or not the conditions can be realized in practice.
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Affiliation(s)
- Christoffer Aberg
- Division of Physical Chemistry, Chemical Center, Lund University, P.O.Box 124, SE-22100 Lund, Sweden.
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13
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Kimble-Hill AC. A review of factors affecting the success of membrane protein crystallization using bicelles. ACTA ACUST UNITED AC 2012. [DOI: 10.1007/s11515-012-1208-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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14
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Fan HY, Nazari M, Chowdhury S, Heerklotz H. Volume and expansivity changes of micelle formation measured by pressure perturbation calorimetry. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2011; 27:1693-1699. [PMID: 21226468 DOI: 10.1021/la1042487] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
We present the application of pressure perturbation calorimetry (PPC) as a new method for the volumetric characterization of the micelle formation of surfactants. The evaluation is realized by a global fit of PPC curves at different surfactant concentration ranging, if possible, from below to far above the CMC. It is based on the knowledge of the temperature dependence of the CMC, which can for example be characterized by isothermal titration calorimetry. We demonstrate the new approach for decyl-β-maltopyranoside (DM). It shows a strong volume increase upon micelle formation of 16 ± 2.5 mL/mol (+4%) at 25 °C, and changes with temperature by -0.1 mL/(mol K). The apparent molar expansivity (E(S)) decreases upon micelle formation from 0.44 to 0.31 mL/(mol K) at 25 °C. Surprisingly, the temperature dependence of the expansivity of DM in solution (as compared with that of maltose) does not agree with the principal behavior described for polar (E(S)(T) decreasing) and hydrophobic (E(S)(T) increasing) solutes or moieties before. The results are discussed in terms of changes in hydration of the molecules and internal packing of the micelles and compared with the volumetric effects of transitions of proteins, DNA, lipids, and polymers.
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Affiliation(s)
- Helen Y Fan
- Leslie Dan Faculty of Pharmacy, University of Toronto, 144 College St., Toronto, ON M5S 3M2, Canada
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15
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A SANS investigation of micelles in mixtures of cetyltrimethylammonium bromide (CTAB)/octyl-β-d-glucopyranoside (C8G1) in water/glycerol solvent. Colloids Surf A Physicochem Eng Asp 2011. [DOI: 10.1016/j.colsurfa.2010.11.071] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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16
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Raudino A, Sarpietro MG, Pannuzzo M. The thermodynamics of simple biomembrane mimetic systems. JOURNAL OF PHARMACY AND BIOALLIED SCIENCES 2011; 3:15-38. [PMID: 21430953 PMCID: PMC3053513 DOI: 10.4103/0975-7406.76462] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2010] [Revised: 10/09/2010] [Accepted: 12/15/2010] [Indexed: 11/04/2022] Open
Abstract
Insight into the forces governing a system is essential for understanding its behavior and function. Thermodynamic investigations provide a wealth of information that is not, or is hardly, available from other methods. This article reviews thermodynamic approaches and assays to measure collective properties such as heat adsorption / emission and volume variations. These methods can be successfully applied to the study of lipid vesicles (liposomes) and biological membranes. With respect to instrumentation, differential scanning calorimetry, pressure perturbation calorimetry, isothermal titration calorimetry, dilatometry, and acoustic techniques aimed at measuring the isothermal and adiabatic processes, two- and three-dimensional compressibilities are considered. Applications of these techniques to lipid systems include the measurement of different thermodynamic parameters and a detailed characterization of thermotropic, barotropic, and lyotropic phase behavior. The membrane binding and / or partitioning of solutes (proteins, peptides, drugs, surfactants, ions, etc.) can also be quantified and modeled. Many thermodynamic assays are available for studying the effect of proteins and other additives on membranes, characterizing non-ideal mixing, domain formation, bilayer stability, curvature strain, permeability, solubilization, and fusion. Studies of membrane proteins in lipid environments elucidate lipid-protein interactions in membranes. Finally, a plethora of relaxation phenomena toward equilibrium thermodynamic structures can be also investigated. The systems are described in terms of enthalpic and entropic forces, equilibrium constants, heat capacities, partial volume changes, volume and area compressibility, and so on, also shedding light on the stability of the structures and the molecular origin and mechanism of the structural changes.
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Affiliation(s)
- Antonio Raudino
- University of Catania, Department of Chemistry, Viale A. Doria 6-95125, Catania, Italy
| | | | - Martina Pannuzzo
- University of Catania, Department of Chemistry, Viale A. Doria 6-95125, Catania, Italy
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17
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Schmidt P, Berger C, Scheidt HA, Berndt S, Bunge A, Beck-Sickinger AG, Huster D. A reconstitution protocol for the in vitro folded human G protein-coupled Y2 receptor into lipid environment. Biophys Chem 2010; 150:29-36. [PMID: 20421142 DOI: 10.1016/j.bpc.2010.02.019] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2010] [Accepted: 02/10/2010] [Indexed: 10/19/2022]
Abstract
Although highly resolved crystal structures of G protein-coupled receptors have become available within the last decade, the need for studying these molecules in their natural membrane environment, where the molecules are rather dynamic, has been widely appreciated. Solid-state NMR spectroscopy is an excellent method to study structure and dynamics of membrane proteins in their native lipid environment. We developed a reconstitution protocol for the uniformly (15)N labeled Y(2) receptor into a bicelle-like lipid structure with high yields suitable for NMR studies. Milligram quantities of target protein were expressed in Escherichia coli using an optimized fermentation process in defined medium yielding in over 10mg/L medium of purified Y(2) receptor solubilized in SDS micelles. The structural integrity of the receptor molecules was strongly increased through refolding and subsequent reconstitution into phospholipid membranes. Specific ligand binding to the integrated receptor was determined using radioligand affinity assay. Further, by NMR measurement a dispersion of the (15)N signals comparable to native rhodopsin was shown. The efficiency of the reconstitution could also be inferred from the fact that reasonable (13)C NMR spectra at natural abundance could be acquired.
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Affiliation(s)
- Peter Schmidt
- Institute of Medical Physics and Biophysics, University of Leipzig, Härtelstr. 16-18, D-04107 Leipzig, Germany
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18
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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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19
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Knauf K, Meister A, Kerth A, Blume A. Interaction of alkyltrimethylammonium bromides with DMPC-d54 and DMPG-d54 monolayers studied by infrared reflection absorption spectroscopy (IRRAS). J Colloid Interface Sci 2010; 342:243-52. [DOI: 10.1016/j.jcis.2009.10.023] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2009] [Revised: 10/12/2009] [Accepted: 10/13/2009] [Indexed: 11/17/2022]
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Caschera F, Gazzola G, Bedau MA, Bosch Moreno C, Buchanan A, Cawse J, Packard N, Hanczyc MM. Automated discovery of novel drug formulations using predictive iterated high throughput experimentation. PLoS One 2010; 5:e8546. [PMID: 20049327 PMCID: PMC2797296 DOI: 10.1371/journal.pone.0008546] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2009] [Accepted: 12/13/2009] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND We consider the problem of optimizing a liposomal drug formulation: a complex chemical system with many components (e.g., elements of a lipid library) that interact nonlinearly and synergistically in ways that cannot be predicted from first principles. METHODOLOGY/PRINCIPAL FINDINGS The optimization criterion in our experiments was the percent encapsulation of a target drug, Amphotericin B, detected experimentally via spectrophotometric assay. Optimization of such a complex system requires strategies that efficiently discover solutions in extremely large volumes of potential experimental space. We have designed and implemented a new strategy of evolutionary design of experiments (Evo-DoE), that efficiently explores high-dimensional spaces by coupling the power of computer and statistical modeling with experimentally measured responses in an iterative loop. CONCLUSIONS We demonstrate how iterative looping of modeling and experimentation can quickly produce new discoveries with significantly better experimental response, and how such looping can discover the chemical landscape underlying complex chemical systems.
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Affiliation(s)
- Filippo Caschera
- ProtoLife Inc., San Francisco, California, United States of America
- Institute of Physics and Chemistry, University of Southern Denmark, Odense, Denmark
| | - Gianluca Gazzola
- ProtoLife Inc., San Francisco, California, United States of America
| | - Mark A. Bedau
- ProtoLife Inc., San Francisco, California, United States of America
- European Center for Living Technology, Venice, Italy
- Reed College, Portland, Oregon, United States of America
- Initiative for Science, Society, and Policy, University of Southern Denmark, Odense, Denmark
| | | | - Andrew Buchanan
- ProtoLife Inc., San Francisco, California, United States of America
| | - James Cawse
- ProtoLife Inc., San Francisco, California, United States of America
- Cawse and Effect, Pittsfield, Massachusetts, United States of America
| | - Norman Packard
- ProtoLife Inc., San Francisco, California, United States of America
- Santa Fe Institute, Santa Fe, New Mexico, United States of America
- European Center for Living Technology, Venice, Italy
| | - Martin M. Hanczyc
- ProtoLife Inc., San Francisco, California, United States of America
- Institute of Physics and Chemistry, University of Southern Denmark, Odense, Denmark
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Monitoring detergent-mediated solubilization and reconstitution of lipid membranes by isothermal titration calorimetry. Nat Protoc 2009; 4:686-97. [PMID: 19373233 DOI: 10.1038/nprot.2009.35] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The solubilization and reconstitution of biological or liposomal membranes by detergents and biomolecules with detergent-like properties play a major role for technical applications (e.g., the isolation of membrane proteins) and biological phenomena (of, e.g., amphiphilic peptides). It is therefore important to know and understand the amounts of a given detergent required for the onset and completion of membrane solubilization and the detergent-lipid interactions in general. Lipid-detergent systems can form a variety of aggregate structures, which can be grouped into two pseudophases (lamellae and micelles) so that solubilization can be approximately described as a phase transition. Here we present a protocol for establishing the phase diagram and a detailed thermodynamic description of a lipid-detergent system based on isothermal titration calorimetry (ITC). The protocol can also be used to detect additive-induced membrane destabilization, permeabilization, domain formation and lipid-dependent transitions between rod-like and spherical micelles. A minimal protocol consisting of all sample preparation procedures and a single solubilization experiment can be accomplished within 2 days; a more extensive series comprising both solubilization and reconstitution experiments requires several days to a few weeks, depending on the number of titrations performed.
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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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Physicochemical Studies on the Interfacial and Bulk Behaviors of Sodium N-Dodecanoyl Sarcosinate (SDDS). J SURFACTANTS DETERG 2008. [DOI: 10.1007/s11743-008-1105-3] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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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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25
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Solubilization of sphingomyelin vesicles by addition of a bile salt. Chem Phys Lipids 2008; 151:10-7. [DOI: 10.1016/j.chemphyslip.2007.09.002] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2007] [Revised: 09/11/2007] [Accepted: 09/19/2007] [Indexed: 10/22/2022]
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26
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Fan Y, Li Y, Cao M, Wang J, Wang Y, Thomas RK. Micellization of dissymmetric cationic gemini surfactants and their interaction with dimyristoylphosphatidylcholine vesicles. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2007; 23:11458-11464. [PMID: 17918867 DOI: 10.1021/la701493s] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
The micellization process of a series of dissymmetric cationic gemini surfactants [CmH2m+1(CH3)2N(CH2)6N(CH3)2C6H13]Br2 (designated as m-6-6 with m = 12, 14, and 16) and their interaction with dimyristoylphosphatidylcholine (DMPC) vesicles have been investigated. In the micellization process of these gemini surfactants themselves, critical micelle concentration (cmc), micelle ionization degree, and enthalpies of micellization (DeltaHmic) were determined, from which Gibbs free energies of micellization (DeltaGmic) and entropy of micellization (DeltaSmic) were derived. These properties were found to be influenced significantly by the dissymmetry in the surfactant structures. The phase diagrams for the solubilization of DMPC vesicles by the gemini surfactants were constructed from calorimetric results combining with the results of turbidity and dynamic light scattering. The effective surfactant to lipid ratios in the mixed aggregates at saturation (Resat) and solubilization (Resol) were derived. For the solubilization of DMPC vesicles, symmetric 12-6-12 is more effective than corresponding single-chain surfactant DTAB, whereas the dissymmetric m-6-6 series are more effective than symmetric 12-6-12, and 16-6-6 is the most effective. The chain length mismatch between DMPC and the gemini surfactants may be responsible for the different Re values. The transfer enthalpy per mole of surfactant within the coexistence range may be associated with the total hydrophobicity of the alkyl chains of gemini surfactants. The transfer enthalpies of surfactant from micelles to bilayers are always endothermic due to the dehydration of headgroups and the disordering of lipid acyl chain packing during the vesicle solubilization.
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Affiliation(s)
- Yanru Fan
- Key Laboratory of Colloid and Interface Science, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100080, People's Republic of China
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27
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Membranolytic activity of bile salts: influence of biological membrane properties and composition. Molecules 2007; 12:2292-326. [PMID: 17978759 DOI: 10.3390/12102292] [Citation(s) in RCA: 88] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2007] [Revised: 10/15/2007] [Accepted: 10/15/2007] [Indexed: 01/15/2023] Open
Abstract
The two main steps of the membranolytic activity of detergents: 1) the partitioning of detergent molecules in the membrane and 2) the solubilisation of the membrane are systematically investigated. The interactions of two bile salt molecules, sodium cholate (NaC) and sodium deoxycholate (NaDC) with biological phospholipid model membranes are considered. The membranolytic activity is analysed as a function of the hydrophobicity of the bile salt, ionic strength, temperature, membrane phase properties, membrane surface charge and composition of the acyl chains of the lipids. The results are derived from calorimetric measurements (ITC, isothermal titration calorimetry). A thermodynamic model is described, taking into consideration electrostatic interactions, which is used for the calculation of the partition coefficient as well as to derive the complete thermodynamic parameters describing the interaction of detergents with biological membranes (change in enthalpy, change in free energy, change in entropy etc). The solubilisation properties are described in a so-called vesicle-to-micelle phase transition diagram. The obtained results are supplemented and confirmed by data obtained from other biophysical techniques (DSC differential scanning calorimetry, DLS dynamic light scattering, SANS small angle neutron scattering).
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Arnulphi C, Sot J, García-Pacios M, Arrondo JLR, Alonso A, Goñi FM. Triton X-100 partitioning into sphingomyelin bilayers at subsolubilizing detergent concentrations: effect of lipid phase and a comparison with dipalmitoylphosphatidylcholine. Biophys J 2007; 93:3504-14. [PMID: 17675347 PMCID: PMC2072071 DOI: 10.1529/biophysj.107.104463] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
We examined the partitioning of the nonionic detergent Triton X-100 at subsolubilizing concentrations into bilayers of either egg sphingomyelin (SM), palmitoyl SM, or dipalmitoylphosphatidylcholine. SM is known to require less detergent than phosphatidylcholine to achieve the same extent of solubilization, and for all three phospholipids solubilization is temperature dependent. In addition, the three lipids exhibit a gel-fluid phase transition in the 38-41 degrees C temperature range. Experiments have been performed at Triton X-100 concentrations well below the critical micellar concentration, so that only detergent monomers have to be considered. Lipid/detergent mol ratios were never <10:1, thus ensuring that the solubilization stage was never reached. Isothermal titration calorimetry, DSC, and infrared, fluorescence, and (31)P-NMR spectroscopies were applied in the 5-55 degrees C temperature range. The results show that, irrespective of the chemical nature of the lipid, DeltaG degrees of partitioning remained in the range of -27 kJ/mol lipid in the gel phase and of -30 kJ/mol lipid in the fluid phase. This small difference cannot account for the observed phase-dependent differences in solubilization. Such virtually constant DeltaG degrees occurred as a result of the compensation of enthalpic and entropic components, which varied with both temperature and lipid composition. Consequently, the observed different susceptibilities to solubilization cannot be attributed to differential binding but to further events in the solubilization process, e.g., bilayer saturability by detergent or propensity to form lipid-detergent mixed micelles. The data here shed light on the relatively unexplored early stages of membrane solubilization and open new ways to understand the phenomenon of membrane resistance toward detergent solubilization.
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Affiliation(s)
- Cristina Arnulphi
- Unidad de Biofísica (Centro Mixto CSIC-UPV/EHU), Departamento de Bioquímica, Universidad del País Vasco, 48080 Bilbao, Spain
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29
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Trépout S, Taveau JC, Mornet S, Benabdelhak H, Ducruix A, Lambert O. Organization of reconstituted lipoprotein MexA onto supported lipid membrane. EUROPEAN BIOPHYSICS JOURNAL: EBJ 2007; 36:1029-37. [PMID: 17665187 DOI: 10.1007/s00249-007-0208-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/14/2007] [Revised: 06/22/2007] [Accepted: 07/10/2007] [Indexed: 01/16/2023]
Abstract
MexA, a periplasmic component of OprM-MexA-MexB tripartite multidrug efflux pump from Pseudomonas aeruginosa, is natively anchored via its fatty acid in the bacteria inner membrane protruding into the periplasm. We used supported lipid bilayer (SLB) to attach the protein to a single leaflet mimicking its perisplamic orientation. For that purpose, we studied the solubilization of DOPC lipid bilayer supported on silica surface with beta-octyl glucoside (betaOG). First we showed that SLBs resist to betaOG concentrations that usually solubilize liposomes. Native form of MexA was directly inserted in the outer leaflet at (betaOG concentrations in a range of 20-25 mM). Second, observations by cryo-electron microscopy (cryoEM) revealed a dense protein layer attached to the surface corresponding to a 13-nm layer of MexA proteins. Analysis of protein densities allows proposing a schematic organization of native MexA inserted in lipid membrane. This structural organization provides further insights with respect to the partially solved structure of the soluble form.
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Affiliation(s)
- Sylvain Trépout
- Laboratoire d'Imagerie Moléculaire et Nano-Bio-Technologie, UMR 5248 CBMN, CNRS, Université Bordeaux 1, ENITAB, IECB, 2 rue Robert Escarpit, 33607, Pessac, France
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30
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Tsamaloukas AD, Keller S, Heerklotz H. Uptake and release protocol for assessing membrane binding and permeation by way of isothermal titration calorimetry. Nat Protoc 2007; 2:695-704. [PMID: 17406632 DOI: 10.1038/nprot.2007.98] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The activity of many biomolecules and drugs crucially depends on whether they bind to biological membranes and whether they translocate to the opposite lipid leaflet and trans aqueous compartment. A general strategy to measure membrane binding and permeation is the uptake and release assay, which compares two apparent equilibrium situations established either by the addition or by the extraction of the solute of interest. Only solutes that permeate the membrane sufficiently fast do not show any dependence on the history of sample preparation. This strategy can be pursued for virtually all membrane-binding solutes, using any method suitable for detecting binding. Here, we present in detail one example that is particularly well developed, namely the nonspecific membrane partitioning and flip-flop of small, nonionic solutes as characterized by isothermal titration calorimetry. A complete set of experiments, including all sample preparation procedures, can typically be accomplished within 2 days. Analogous protocols for studying charged solutes, virtually water-insoluble, hydrophobic compounds or specific ligands are also considered.
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Affiliation(s)
- Alekos D Tsamaloukas
- Department of Chemistry and Physics, University of Toronto, 80 Saint George Street, Toronto, Ontario, Canada M5S 3H6
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31
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Heerklotz H, Seelig J. Leakage and lysis of lipid membranes induced by the lipopeptide surfactin. EUROPEAN BIOPHYSICS JOURNAL: EBJ 2006; 36:305-14. [PMID: 17051366 DOI: 10.1007/s00249-006-0091-5] [Citation(s) in RCA: 144] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/15/2006] [Revised: 08/11/2006] [Accepted: 08/25/2006] [Indexed: 11/25/2022]
Abstract
Surfactin is a lipopeptide produced by Bacillus subtilis which possesses antimicrobial activity. We have studied the leakage and lysis of POPC vesicles induced by surfactin using calcein fluorescence de-quenching, isothermal titration calorimetry and (31)P solid state NMR. Membrane leakage starts at a surfactin-to-lipid ratio in the membrane, R (b) approximately 0.05, and an aqueous surfactin concentration of C (S) (w) approximately 2 microM. The transient, graded nature of leakage and the apparent coupling with surfactin translocation to the inner leaflet of the vesicles, suggests that this low-concentration effect is due to a bilayer-couple mechanism. Different permeabilization behaviour is found at R (b) approximately 0.15 and attributed to surfactin-rich clusters, which can induce leaks and stabilize them by covering their hydrophobic edges. Membrane lysis or solubilization to micellar structures starts at R (b) (sat) = 0.22 and C (S) (w) = 9 microM and is completed at R (m) (sol) = 0.43 and C (S) (w) = 11 microM. The membrane-water partition coefficient of surfactin is obtained as K = 2 x 10(4) M(-1). These data resolve inconsistencies in the literature and shed light on the variety of effects often referred to as detergent-like effects of antibiotic peptides on membranes. The results are compared with published parameters characterizing the hemolytic and antibacterial activity.
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32
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Tsamaloukas A, Szadkowska H, Heerklotz H. Nonideal mixing in multicomponent lipid/detergent systems. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2006; 18:S1125-S1138. [PMID: 21690833 DOI: 10.1088/0953-8984/18/28/s02] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
A detailed understanding of the mixing properties of membranes to which detergents are added is mandatory for improving the application and interpretation of detergent based protein or lipid extraction assays. For Triton X-100 (TX-100), a nonionic detergent frequently used in the process of solubilizing and purifying membrane proteins and lipids, we present here a detailed study of the mixing properties of binary and ternary lipid mixtures by means of high-sensitivity isothermal titration calorimetry (ITC). To this end the partitioning thermodynamics of TX-100 molecules from the aqueous phase to lipid bilayers composed of various mixtures of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC), egg-sphingomyelin (SM), and cholesterol (cho) are characterized. Composition-dependent partition coefficients K are analysed within the frame of a thermodynamic model developed to describe nonideal mixing in multicomponent lipid/detergent systems. The results imply that POPC, fluid SM, and TX-100 mix almost ideally (nonideality parameters |ρ(α/β)|<RT). However, favourable SM/cho (ρ(SM/cho)≤-6RT) and unfavourable PC/cho interactions (ρ(PC/cho) = 2RT) may under certain conditions cause POPC/TX-100-enriched domains to segregate from SM/cho-enriched ones. TX-100/cho contacts are unfavourable (ρ(cho/TX) = 4RT), so the system tends to avoid them. That means, addition of TX-100 promotes the separation of SM/cho-rich from PC/TX-100-rich domains. It appears that cho/detergent interactions are crucial governing the abundance and composition of detergent-resistant membrane patches.
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Affiliation(s)
- Alekos Tsamaloukas
- Biozentrum of the University of Basel, Division of Biophysical Chemistry, Klingelbergstrasse 70, CH-4056 Basel, Switzerland
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Beyer K, Leine D, Blume A. The demicellization of alkyltrimethylammonium bromides in 0.1M sodium chloride solution studied by isothermal titration calorimetry. Colloids Surf B Biointerfaces 2006; 49:31-9. [PMID: 16580819 DOI: 10.1016/j.colsurfb.2006.02.003] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2005] [Accepted: 02/13/2006] [Indexed: 10/24/2022]
Abstract
The demicellization of the cationic detergents dodecyltrimethylammonium bromide, tetradecyltrimetylammonium bromide, and cetyltrimethylammonium bromide was studied at temperatures between 20 and 60 degrees C in 0.1 M NaCl (pH 6.4) using isothermal titration calorimetry (ITC). We determined the critical micellization concentration (cmc) of the cationic detergents which show a minimum at temperatures between 20 and 34 degrees C. In accordance with the lengthening of the hydrophobic tail of the detergents the cmc decreases with increasing alkyl chain length. The thermodynamic parameters describing the changes of enthalpy (DeltaH(demic)), the changes of entropy (DeltaS(demic)) and the Gibbs free energy change (DeltaG(demic)) for demicellization were first obtained using the pseudophase-separation model. The aggregation number n at the cmc as well as the demicellization enthalpy, entropy and Gibbs free energy change were also calculated using a simulation based on the mass-action model. Furthermore, we investigated the demicellization of CTAB in deionized water in comparison to demicellization in sodium chloride solution to determine the influence of counter ion binding on the demicellization.
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Affiliation(s)
- Katja Beyer
- Martin-Luther-University Halle-Wittenberg, Institute of Physical Chemistry, Muehlpforte 1, D-06108 Halle/Saale, Germany
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Barriocanal L, Taylor KMG, Buckton G. Bilayer to micelle transition of DMPC and alcohol ethoxylate surfactants as studied by isoperibol calorimetry. J Pharm Sci 2005; 94:1747-55. [PMID: 15986468 DOI: 10.1002/jps.20390] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The interaction of dimyristoylphosphatidylcholine (DMPC) with non-ionic surfactants has been studied using isoperibol calorimetry. Phospholipid-surfactant systems were formed in the isoperibol calorimeter with varying amounts of surfactant and the change in enthalpy on formation was measured. Solubilization of the phospholipid lamellae was assessed as a decrease in the enthalpy of reaction of co-films containing DMPC and increasing amounts of three linear alcohol ethoxylate surfactants: C(10)H(21)(OCH(2)CH(2))(3)OH, C(10)H(21)(OCH(2)CH(2))(5)OH, or C(12)H(25)(OCH(2)CH(2))(7)OH. The isoperibol calorimetry data for DMPC/surfactant/water systems were consistent with a theoretical three-stage model for the solubilization of phospholipids by surfactants, whereby phospholipid bilayers are transformed into mixed micelles with increasing amounts of surfactant. The results indicate that: (i) the interaction between phospholipid and surfactants results in a non-linear correlation between the enthalpy of reaction and the surfactant concentration; (ii) the structural stage of the lamellar to micelle transition (mixed bilayers, mixed micelles, or both) can be determined from calorimetric data; (iii) phase boundaries in the solubilization process (bilayer saturation, micelle saturation) can be identified as break points in the enthalpy-concentration curve; and (iv) increasing the hydrophilicity of the surfactant results in a decrease of the surfactant concentration producing the onset of solubilization.
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Affiliation(s)
- Leticia Barriocanal
- Department of Pharmaceutics, School of Pharmacy, University of London, 29-39 Brunswick Square, London WC1N 1AX, United Kingdom
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35
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Hildebrand A, Beyer K, Neubert R, Garidel P, Blume A. Solubilization of negatively charged DPPC/DPPG liposomes by bile salts. J Colloid Interface Sci 2005; 279:559-71. [PMID: 15464825 DOI: 10.1016/j.jcis.2004.06.085] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2004] [Accepted: 06/27/2004] [Indexed: 12/01/2022]
Abstract
The interactions of the bile salts sodium cholate (NaC) and sodium deoxycholate (NaDC) in 0.1 M NaCl (pH 7.4) with membranes composed of 1,2-dipalmitoyl-sn-glycero-3-phosphatidylcholine (DPPC), 1,2-dipalmitoyl-sn-glycero-3-phosphatidylglycerol (DPPG) and mixtures of DPPC and DPPG at molar ratios of 3:1 and 1:1 were studied by means of high-sensitivity isothermal titration calorimetry (ITC), dynamic light scattering (DLS), and differential scanning calorimetry (DSC). The partition coefficients and the transfer enthalpies for the incorporation of bile salt molecules into the phospholipid membranes were determined by ITC. The vesicle-to-micelle transition was investigated by ITC, DLS, and DSC. The phase boundaries for the saturation of the vesicles and their complete solubilization established by ITC were in general agreement with DLS data, but systematic differences could be seen due to the difference in detected physical quantities. Electrostatic repulsion effects between the negatively charged bile salt molecules and the negatively charged membrane surfaces are not limiting factors for the vesicle-to-micelle transition. The membrane packing constraints of the phospholipid molecules and the associated spontaneous curvature of the vesicles play the dominant role. DPPG vesicles are transformed by the bile salts into mixed micelles more easily or similarly compared to DPPC vesicles. The saturation of mixed DPPC/DPPG vesicles requires less bile salt, but to induce the solubilization of the liposomes, significantly higher amounts of bile salt are needed compared to the concentrations required for the solubilization of the pure phospholipid systems. The different solubilization behavior of DPPC/DPPG liposomes compared to the pure liposomes could be due to a specific "extraction" of DPPG into the mixed micelles in the coexistence region.
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Affiliation(s)
- Annegret Hildebrand
- Martin-Luther-University Halle-Wittenberg, Institute of Pharmaceutical Technology and Biopharmaceutics, Wolfgang-Langenbeck-Str. 4, D-06120 Halle/Saale, Germany
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36
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Tsamaloukas A, Szadkowska H, Slotte PJ, Heerklotz H. Interactions of cholesterol with lipid membranes and cyclodextrin characterized by calorimetry. Biophys J 2005; 89:1109-19. [PMID: 15923231 PMCID: PMC1366596 DOI: 10.1529/biophysj.105.061846] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Interactions of cholesterol (cho) with different lipids are commonly believed to play a key role in the formation of functional domains in membranes. We introduce a novel approach to characterize cho-lipid interactions by isothermal titration calorimetry. Cho is solubilized in the aqueous phase by reversible complexation with methyl-beta-cyclodextrin (cyd). Uptake of cho into the membrane is measured upon a series of injections of lipid vesicles into a cyd/cho solution. As an independent assay, cho release from membranes is measured upon titrating lipid/cho mixed vesicles into a cyd solution. The most consistent fit to the data is obtained with a mole fraction (rather than mole ratio) partition coefficient and considering a cho/cyd stoichiometry of 1:2. The results are discussed in terms of contributions from 1), the transfer of cho from cyd into a hypothetical, ideally mixed membrane and 2), from nonideal interactions with POPC. The latter are exothermic but opposed by a strong loss in entropy, in agreement with cho-induced acyl chain ordering and membrane condensation. They are accompanied by a positive heat capacity change which cannot be interpreted in terms of the hydrophobic effect, suggesting that additive-induced chain ordering itself increases the heat capacity. The new assays have a great potential for a better understanding of sterol-lipid interactions and yield suggestions how to optimize cho extraction from membranes.
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Affiliation(s)
- Alekos Tsamaloukas
- Biozentrum of the University of Basel, Division of Biophysical Chemistry, Switzerland
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Hildebrand A, Garidel P, Neubert R, Blume A. Thermodynamics of demicellization of mixed micelles composed of sodium oleate and bile salts. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2004; 20:320-328. [PMID: 15743073 DOI: 10.1021/la035526m] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Isothermal titration calorimetry (ITC) was used to determine the critical micelle concentration (cmc) and the thermodynamic parameters associated with the demicellization of sodium oleate (NaO) and mixed micelles composed of the bile salt (BS) sodium cholate (NaC) or sodium deoxycholate (NaDC), respectively, and NaO at a molar ratio of 5:2. The influence of the ionic strength (pure water and 0.1 M NaCl at pH 7.5) as well as that of the temperature (10-70 degrees C) were analyzed. For NaO, two cmc's were detected, indicating a two-step aggregation process, whereas only one cmc was observed for the two BSs. A single aggregation mechanism is also evident for the demicellization of mixed micelles (BS/NaO 5:2). Increasing the ionic strength induces the well-known decrease of the cmc. The cmc shows a minimum at room temperature. The cmc(mix) of the mixed micelles was analyzed using models assuming an ideal or nonideal mixing behavior of both detergents. The thermodynamic parameters describing the enthalpy (deltaHdemic), entropy (deltaSdemic), and Gibbs energy change (deltaGdemic), as well as the change in heat capacity (deltaCp,demic) for demicellization, were obtained from one ITC experiment. From the temperature dependence of deltaHdemic, the change of the hydrophobic surface area of the detergents from the micellar into the aqueous phase was derived. In all cases, the deltaCp,demic values are positive. In addition, the temperature dependence of the size of the formed aggregates was studied by dynamic light scattering (DLS). DLS indicated two populations of aggregates in the mixed system, small primary micelles (0.5-2 nm), and larger aggregates with a hydrodynamic radius in the range of 50-150 nm.
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Affiliation(s)
- Annegret Hildebrand
- Institute of Pharmaceutical Technology and Biopharmaceutics, Martin-Luther-University Halle-Wittenberg, D-06120 Halle/Saale, Germany
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Meister A, Kerth A, Blume A. The interaction of n-nonyl-β-d-glucopyranoside and sodium dodecyl sulfate with DMPC and DMPG monolayers studied by infrared reflection absorption spectroscopy. Phys Chem Chem Phys 2004. [DOI: 10.1039/b410761f] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Meister A, Blume A. Solubilization of DMPC-d54and DMPG-d54vesicles with octylglucoside and sodium dodecyl sulfate studied by FT-IR spectroscopy. Phys Chem Chem Phys 2004. [DOI: 10.1039/b312533e] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Hildebrand A, Beyer K, Neubert R, Garidel P, Blume A. Temperature dependence of the interaction of cholate and deoxycholate with fluid model membranes and their solubilization into mixed micelles. Colloids Surf B Biointerfaces 2003. [DOI: 10.1016/j.colsurfb.2003.08.001] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Takegami S, Kitamura K, Kitade T, Kitagawa A, Kawamura K. Thermodynamics of partitioning of phenothiazine drugs between phosphatidylcholine bilayer vesicles and water studied by second-derivative spectrophotometry. Chem Pharm Bull (Tokyo) 2003; 51:1056-9. [PMID: 12951447 DOI: 10.1248/cpb.51.1056] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The partition coefficients (Kps) of phenothiazine drugs (trifluoperazine, triflupromazine, chlorpromazine and promazine) between phosphatidylcholine (PC) small unilamellar vesicles (SUV) and water were determined over the temperature range of 10-40 degrees C by a second-derivative spectrophotometric method. The second derivative spectra of each drug solution containing various amounts of SUV showed distinct derivative isosbestic points confirming the entire elimination of the residual background signal effects of the SUV. The Kp values were calculated from the derivative intensity change of the drugs induced by the addition of SUV to the drug buffer solutions (pH 7.4) and obtained with the R.S.D. below 10% (n=3). The van't Hoff analysis of the temperature dependence of Kp values revealed negative deltaH(w-->l) and positive deltaS(w-->l), suggesting an enthalpy/entropy driven mechanism for the phenothiazine partitioning. The negative deltaH(w-->l) implies that the electrostatic interaction, positively charged alkyl amino groups of phenothiazine drugs with negatively charged phosphate groups on the surface of PC SUV, partly contributes to the partitioning. The existence of halogen atom(s) on the phenothiazine ring at position C-2 enhanced the Kp value (H<Cl<CF3). This enhancement can be accounted for by an increase in the deltaS(w-->l) value (H<Cl<CF3), and the deltaS(w-->l) increase is considered to be enhancement of disorder in the hydrophobic acyl chain regions of PC SUV membranes derived from the phenothiazine ring insertion and thus depends on the bulkiness of the substituent. The enthalpy-entropy correlation analysis yielding a good linear relationship also suggests that the phenothiazine drugs studied have identically an enthalpy-entropy compensation mechanism for the partitioning.
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Majhi PR, Blume A. Temperature-Induced Micelle-Vesicle Transitions in DMPC−SDS and DMPC−DTAB Mixtures Studied by Calorimetry and Dynamic Light Scattering. J Phys Chem B 2002. [DOI: 10.1021/jp025849b] [Citation(s) in RCA: 88] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Lasch J, Hildebrand A. Isothermic titration calorimetry to study CMCs of neutral surfactants and of the liposome-forming bolaamphiphile dequalinium. J Liposome Res 2002; 12:51-6. [PMID: 12604038 DOI: 10.1081/lpr-120004776] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Isothermic titration calorimetry was used to measure the heat of micelle formation (molar enthalpy of transfer of surfactants monomers from water into micellar aggregates. The problems associated with the estimation of the CMC and the whole therodynamic profile of micellization of surfactants via Gibbs-Helmholtz-Equation are discussed. CMC's of octylthioglucoside and the peculiar bolaamphilphile dequalinium which concentrates in mitochondria are measured. In contrast to earlier reports, no CMC of dequalinium could be found inspite of extensive systematic measurements.
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Affiliation(s)
- Jürgen Lasch
- Institute of Physiological Chemistry, Martin-Luther-University, Halle-Wittenberg, Germany
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López O, Cócera M, Coderch L, Parra JL, Barsukov L, de la Maza A. Octyl Glucoside-Mediated Solubilization and Reconstitution of Liposomes: Structural and Kinetic Aspects. J Phys Chem B 2001. [DOI: 10.1021/jp010273w] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Olga López
- Departamento de Tensioactivos, Instituto de Investigaciones Químicas y Ambientales de Barcelona (IIQAB), Consejo Superior de Investigaciones Científicas (CSIC), C/ Jordi Girona, 18-26, 08034 Barcelona, Spain, and Shemyakin-Ovchinnikov Institute of Biorganic Chemistry, Russian Academy of Sciences, UI. Miklukho-Maklaya, 16/10, 117871 Moscow V-437, Russia
| | - Mercedes Cócera
- Departamento de Tensioactivos, Instituto de Investigaciones Químicas y Ambientales de Barcelona (IIQAB), Consejo Superior de Investigaciones Científicas (CSIC), C/ Jordi Girona, 18-26, 08034 Barcelona, Spain, and Shemyakin-Ovchinnikov Institute of Biorganic Chemistry, Russian Academy of Sciences, UI. Miklukho-Maklaya, 16/10, 117871 Moscow V-437, Russia
| | - Luisa Coderch
- Departamento de Tensioactivos, Instituto de Investigaciones Químicas y Ambientales de Barcelona (IIQAB), Consejo Superior de Investigaciones Científicas (CSIC), C/ Jordi Girona, 18-26, 08034 Barcelona, Spain, and Shemyakin-Ovchinnikov Institute of Biorganic Chemistry, Russian Academy of Sciences, UI. Miklukho-Maklaya, 16/10, 117871 Moscow V-437, Russia
| | - Jose Luis Parra
- Departamento de Tensioactivos, Instituto de Investigaciones Químicas y Ambientales de Barcelona (IIQAB), Consejo Superior de Investigaciones Científicas (CSIC), C/ Jordi Girona, 18-26, 08034 Barcelona, Spain, and Shemyakin-Ovchinnikov Institute of Biorganic Chemistry, Russian Academy of Sciences, UI. Miklukho-Maklaya, 16/10, 117871 Moscow V-437, Russia
| | - Leonid Barsukov
- Departamento de Tensioactivos, Instituto de Investigaciones Químicas y Ambientales de Barcelona (IIQAB), Consejo Superior de Investigaciones Científicas (CSIC), C/ Jordi Girona, 18-26, 08034 Barcelona, Spain, and Shemyakin-Ovchinnikov Institute of Biorganic Chemistry, Russian Academy of Sciences, UI. Miklukho-Maklaya, 16/10, 117871 Moscow V-437, Russia
| | - Alfonso de la Maza
- Departamento de Tensioactivos, Instituto de Investigaciones Químicas y Ambientales de Barcelona (IIQAB), Consejo Superior de Investigaciones Científicas (CSIC), C/ Jordi Girona, 18-26, 08034 Barcelona, Spain, and Shemyakin-Ovchinnikov Institute of Biorganic Chemistry, Russian Academy of Sciences, UI. Miklukho-Maklaya, 16/10, 117871 Moscow V-437, Russia
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Lichtenberg D, Opatowski E, Kozlov MM. Phase boundaries in mixtures of membrane-forming amphiphiles and micelle-forming amphiphiles. BIOCHIMICA ET BIOPHYSICA ACTA 2000; 1508:1-19. [PMID: 11090815 DOI: 10.1016/s0304-4157(00)00004-6] [Citation(s) in RCA: 125] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The phase behavior of mixtures of phospholipids and detergents in aqueous solutions is an issue of basic importance for understanding the solubilization and reconstitution of biological membranes. We review the existing knowledge on the compositionally induced reversible transformation of phospholipid bilayers into lipid-detergent mixed micelles. First, we describe the experimental protocols used for preparation of such mixtures and emphasize the scope and limitations of the various techniques used for evaluation of the microstructures of the self-assembled amphiphiles in the mixture. Subsequently, we interpret the existing data in terms of the spontaneous curvature of the amphiphiles and the finite size of the mixed micelles. These considerations lead to a general description of the phase behavior, which forms the basis for a rational approach to solubilization and reconstitution experiments.
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Affiliation(s)
- D Lichtenberg
- Department of Physiology and Pharmacology, Tel Aviv University, Sackler Faculty of Medicine, 69978, Tel Aviv, Israel.
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Heerklotz H, Seelig J. Titration calorimetry of surfactant-membrane partitioning and membrane solubilization. BIOCHIMICA ET BIOPHYSICA ACTA 2000; 1508:69-85. [PMID: 11090819 DOI: 10.1016/s0304-4157(00)00009-5] [Citation(s) in RCA: 177] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
The interaction of surfactants with membranes has been difficult to monitor since most detergents are small organic molecules without spectroscopic markers. The development of high sensitivity isothermal titration calorimetry (ITC) has changed this situation distinctly. The insertion of a detergent into the bilayer membrane is generally accompanied by a consumption or release of heat which can be measured fast and reliably with modern titration calorimeters. It is possible to determine the full set of thermodynamic parameters, i.e., the partitioning enthalpy, the partitioning isotherm, the partition coefficient, the free energy, and the entropy of transfer. The application of ITC to the following problems is described: (i) measurement of the critical micellar concentration (CMC) of pure detergent solutions; (ii) analysis of surfactant-membrane partitioning equilibria, including asymmetric insertion; and (iii) membrane-surfactant phase diagrams. Finally, the thermodynamic parameters derived for non-ionic detergents are discussed and the affinity for micelle formation is compared with membrane incorporation.
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Affiliation(s)
- H Heerklotz
- Department of Biophysical Chemistry, Biocenter of the University of Basel, Klingelbergstrasse 70, CH-4056, Basel, Switzerland
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Heerklotz H, Seelig J. Correlation of membrane/water partition coefficients of detergents with the critical micelle concentration. Biophys J 2000; 78:2435-40. [PMID: 10777739 PMCID: PMC1300832 DOI: 10.1016/s0006-3495(00)76787-7] [Citation(s) in RCA: 161] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
The membrane/water partition coefficients, K, of 15 electrically neutral (non-charged or zwitterionic) detergents were measured with phospholipid vesicles by using isothermal titration calorimetry, and were compared to the corresponding critical micellar concentrations, cmc. The detergents measured were oligo(ethylene oxide) alkyl ethers (C(m)EO(n) with m = 10/n = 3, 7 and m = 12/n = 3.8); alkylglucosides (octyl, decyl); alkylmaltosides (octyl, decyl, dodecyl); diheptanoylphosphatidylcholine; Tritons (X-100, X-114) and CHAPS. A linear relation between the free energies of partitioning into the membrane and micelle formation was found such that K. CMC approximately 1. The identity K. CMC = 1 was used to classify detergents with respect to their membrane disruption potency. "Strong" detergents are characterized by K. CMC < 1 and solubilize lipid membranes at detergent-to-lipid ratios X(b) < 1 (alkylmaltosides, tritons, heptaethylene glycol alkyl ethers). "Weak" detergents are characterized by K. CMC > 1 and accumulate in the membrane- to detergent-to-lipid ratios X(b) > 1 before the bilayer disintegrates (alkylglucosides, pentaethylene glycol dodecyl ether).
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Affiliation(s)
- H Heerklotz
- Department of Biophysical Chemistry, Biocenter of the University of Basel, Basel, Switzerland
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Gliss C, Casalta H, Bayerl TM. Surfactant-Induced Alterations of Lecithin Molecular Dynamics in Bilayers Studied by Quasielastic Neutron Scattering and Solid-State NMR. J Phys Chem B 1999. [DOI: 10.1021/jp991505i] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Christine Gliss
- Institut für Experimentelle Physik V, Universität Würzburg, 97074 Würzburg, Germany, and Institut Max von Laue−Paul Langevin, Avenue des Martyrs, 38042 Grenoble Cedex 9, France
| | - Helene Casalta
- Institut für Experimentelle Physik V, Universität Würzburg, 97074 Würzburg, Germany, and Institut Max von Laue−Paul Langevin, Avenue des Martyrs, 38042 Grenoble Cedex 9, France
| | - Thomas M. Bayerl
- Institut für Experimentelle Physik V, Universität Würzburg, 97074 Würzburg, Germany, and Institut Max von Laue−Paul Langevin, Avenue des Martyrs, 38042 Grenoble Cedex 9, France
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Nosjean O, Roux B. Ectoplasmic insertion of a glycosylphosphatidylinositol-anchored protein in glycosphingolipid- and cholesterol-containing phosphatidylcholine vesicles. EUROPEAN JOURNAL OF BIOCHEMISTRY 1999; 263:865-70. [PMID: 10469152 DOI: 10.1046/j.1432-1327.1999.00573.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Glycosylphosphatidylinositol (glycosyl-PtdIns)-anchored proteins are proposed to be clustered in membrane microdomains enriched in cholesterol and glycosphingolipids (GlySphs). We have prepared biomimetic membranes in order to study the possible phenomena of surface aggregation of these membrane components. Phosphatidylcholine liposomes were treated by octylglucoside to insert a glycosyl-PtdIns-protein, alkaline phosphatase (ALP), some cholesterol, and a GlySph, the lactocerebroside. The association of these compounds was shown by centrifugation on a density gradient. The presence of ALP on the surface of the vesicles was shown by the action of a phospholipase, and the presence of the lactocerebroside was shown by the use of a galactose-specific tetravalent lectin. Our data show that total alkaline phosphatase and half to total lactocerebroside were ectoplasmically inserted in the vesicles membrane. In addition, we observed that the presence of small amounts of ALP in the liposomes led to significant changes in membrane stability with regard to detergent, as shown by the changes in the solubilization process monitored by turbidimetry. Furthermore, we have built an original method to study the cohesion of the vesicles membrane, in which some magnesium ions were trapped in the luminal space of the liposomes during several days. The ALP is magnesium-dependent for its catalytic activity and was inhibited after incubation of ALP-containing liposomes in a magnesium-free buffer. The ALP activity was restored by the addition of detergent to the liposomes, due to the release of the luminal magnesium ions. Surface aggregation phenomena will now be investigated by atomic force microscopy.
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Affiliation(s)
- O Nosjean
- Laboratoire de Physico-chimie Biologique, UPRESA CNRS 5013, Université C. Bernad Lyon 1, France.
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