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Deike S, Malke M, Lechner BD, Binder WH. Constraining Polymers into β-Turns: Miscibility and Phase Segregation Effects in Lipid Monolayers. Polymers (Basel) 2017; 9:E369. [PMID: 30971043 PMCID: PMC6418963 DOI: 10.3390/polym9080369] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2017] [Revised: 08/11/2017] [Accepted: 08/13/2017] [Indexed: 11/17/2022] Open
Abstract
Abstract: Investigation of model biomembranes and their interactions with natural or synthetic macromolecules are of great interest to design membrane systems with specific properties such as drug-delivery. Here we study the behavior of amphiphilic β-turn mimetic polymer conjugates at the air⁻water interface and their interactions with lipid model membranes. For this endeavor we synthesized two different types of conjugates containing either hydrophobic polyisobutylene (PIB, Mn = 5000 g·mol-1) or helical poly(n-hexyl isocyanate) (PHIC, Mn = 4000 g·mol-1), both polymers being immiscible, whereas polyisobutylene as a hydrophobic polymer can incorporate into lipid membranes. The conjugates were investigated using Langmuir-film techniques coupled with epifluorescence microscopy and AFM (Atomic Force Microscopy), in addition to their phase behavior in mixed lipid/polymer membranes composed of DPPC (dipalmitoyl-sn-glycero-3-phosphocholine). It was found that the DPPC monolayers are strongly disturbed by the presence of the polymer conjugates and that domain formation of the polymer conjugates occurs at high surface pressures (π > 30 mN·m-1).
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Affiliation(s)
- Stefanie Deike
- Faculty of Natural Science II, Martin Luther University Halle-Wittenberg, Von-Danckelmann-Platz 4, 06120 Halle (Saale), Germany.
| | - Marlen Malke
- Faculty of Natural Science II, Martin Luther University Halle-Wittenberg, Von-Danckelmann-Platz 4, 06120 Halle (Saale), Germany.
| | - Bob-Dan Lechner
- Faculty of Natural Science II, Martin Luther University Halle-Wittenberg, Von-Danckelmann-Platz 4, 06120 Halle (Saale), Germany.
- School of Physics, University of Exeter, Stocker Road, Exeter EX4, UK.
| | - Wolfgang H Binder
- Faculty of Natural Science II, Martin Luther University Halle-Wittenberg, Von-Danckelmann-Platz 4, 06120 Halle (Saale), Germany.
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Clark GA, Henderson JM, Heffern C, Akgün B, Majewski J, Lee KYC. Synergistic Interactions of Sugars/Polyols and Monovalent Salts with Phospholipids Depend upon Sugar/Polyol Complexity and Anion Identity. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2015; 31:12688-12698. [PMID: 26496486 DOI: 10.1021/acs.langmuir.5b02815] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
We found that interactions of dipalmitoylphosphatidylcholine (DPPC) lipid monolayers with sugars are influenced by addition of NaCl. This work is of general importance in understanding how sugar-lipid-salt interactions impact biological systems. Using Langmuir isothermal compressions, fluorescence microscopy, atomic force microscopy, and neutron reflectometry, we examined DPPC monolayers upon addition of sugars/polyols and/or monovalent salts. Sugar-lipid interactions in the presence of NaCl increased with increasing complexity of the sugar/polyol in the order glycerol ≪ glucose < trehalose. When the anion was altered in the series NaF, NaCl, and NaBr, only minor differences were observed. When comparing LiCl, NaCl, and KCl, sodium chloride had the greatest influence on glucose and trehalose interactions with DPPC. We propose that heterogeneity created by cation binding allows for sugars to bind the lipid headgroups. While cation binding increases in the order K(+) < Na(+) < Li(+), lithium ions may also compete with glucose for binding sites. Thus, both cooperative and competitive factors contribute to the overall influence of salts on sugar-lipid interactions.
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Affiliation(s)
- Ginevra A Clark
- Department of Chemistry, Institute for Biophysical Dynamics, James Franck Institute, The University of Chicago , Chicago, Illinois 60637, United States
| | - J Michael Henderson
- Department of Chemistry, Institute for Biophysical Dynamics, James Franck Institute, The University of Chicago , Chicago, Illinois 60637, United States
| | - Charles Heffern
- Department of Chemistry, Institute for Biophysical Dynamics, James Franck Institute, The University of Chicago , Chicago, Illinois 60637, United States
| | - Bülent Akgün
- Department of Chemistry, Bogazici University , Bebek, Istanbul 34342, Turkey
- National Institute of Standards and Technology, Gaithersburg, Maryland 20899-6102, United States
- Department of Materials Science and Engineering, University of Maryland , College Park, Maryland 20742, United States
| | - Jaroslaw Majewski
- Los Alamos Neutron Scattering Center/MPA/CINT, Los Alamos National Laboratory , Los Alamos, New Mexico 87545, United States
- Department of Chemical Engineering, University of California , Davis, California 95616, United States
| | - Ka Yee C Lee
- Department of Chemistry, Institute for Biophysical Dynamics, James Franck Institute, The University of Chicago , Chicago, Illinois 60637, United States
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Malke M, Barqawi H, Binder WH. Synthesis of an Amphiphilic β-Turn Mimetic Polymer Conjugate. ACS Macro Lett 2014; 3:393-397. [PMID: 35590752 DOI: 10.1021/mz500108n] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
A new biomimetic polymer containing a beta-turn mimetic element (1) was synthesized, using a combination of living carbocationic polymerization (LCCP), amidation, and "click" chemistry. Two different α-ω-functionalized polyisobutylenes (PIBs 3 and 5) bearing either an alkyne group (PIB 3) or a primary amine group (PIB 5) were directly synthesized via LCCP. The linking of the two PIB strands with the closely positioned carboxyl/azido moieties of a β-turn dipeptide (BTD) 2 was achieved via a sequence of amidation reaction and the CuI-mediated azide/alkyne "click" reaction. By means of size exclusion chromatography (SEC), matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS), NMR spectroscopy, and LC/MALDI-TOF MS, a detailed structural proof of the β-turn mimetic PIB conjugate (1) was possible.
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Affiliation(s)
- Marlen Malke
- Chair of Macromolecular Chemistry, Institute of Chemistry, Division of Technical and Macromolecular Chemistry, Faculty of Natural Sciences II (Chemistry, Physics and Mathematics), Martin-Luther-University Halle-Wittenberg, von-Danckelmann-Platz 4, Halle D-06120, Germany
| | - Haitham Barqawi
- Chair of Macromolecular Chemistry, Institute of Chemistry, Division of Technical and Macromolecular Chemistry, Faculty of Natural Sciences II (Chemistry, Physics and Mathematics), Martin-Luther-University Halle-Wittenberg, von-Danckelmann-Platz 4, Halle D-06120, Germany
| | - Wolfgang H. Binder
- Chair of Macromolecular Chemistry, Institute of Chemistry, Division of Technical and Macromolecular Chemistry, Faculty of Natural Sciences II (Chemistry, Physics and Mathematics), Martin-Luther-University Halle-Wittenberg, von-Danckelmann-Platz 4, Halle D-06120, Germany
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Yuwen T, Post CB, Skrynnikov N. Domain cooperativity in multidomain proteins: what can we learn from molecular alignment in anisotropic media? JOURNAL OF BIOMOLECULAR NMR 2011; 51:131-50. [PMID: 21947922 PMCID: PMC4721247 DOI: 10.1007/s10858-011-9548-7] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/09/2011] [Accepted: 07/07/2011] [Indexed: 05/13/2023]
Abstract
Many proteins have modular design with multiple globular domains connected via flexible linkers. As a simple model of such system, we study a tandem construct consisting of two identical SH3 domains and a variable-length Gly/Ser linker. When the linker is short, this construct represents a dumbbell-shaped molecule with limited amount of domain-domain mobility. Due to its elongated shape, this molecule efficiently aligns in steric alignment media. As the length of the linker increases, the two domains become effectively uncoupled and begin to behave as independent entities. Consequently, their degree of alignment drops, approaching that found in the (near-spherical) isolated SH3 domains. To model the dependence of alignment parameters on the length of the interdomain linker, we have generated in silico a series of conformational ensembles representing SH3 tandems with different linker length. These ensembles were subsequently used as input for alignment prediction software PALES. The predicted alignment tensors were compared with the results of experimental measurements using a series of tandem-SH3 samples in PEG/hexanol alignment media. This comparison broadly confirmed the expected trends. At the same time, it has been found that the isolated SH3 domain aligns much stronger than expected. This finding can be attributed to complex morphology of the PEG/hexanol media and/or to weak site-specific interactions between the protein and the media. In the latter case, there are strong indications that electrostatic interactions may play a role. The fact that PEG/hexanol does not behave as a simple steric media should serve as a caution for studies that use PALES as a quantitative prediction tool (especially for disordered proteins). Further progress in this area depends on our ability to accurately model the anisotropic media and its site-specific interactions with protein molecules. Once this ability is improved, it should be possible to use the alignment parameters as a measure of domain-domain cooperativity, thus identifying the situations where two domains transiently interact with each other or become coupled through a partially structured linker.
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Affiliation(s)
- Tairan Yuwen
- Department of Chemistry, Purdue University, West Lafayette IN 47907, USA
| | - Carol Beth Post
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette IN 47907, USA
| | - Nikolai Skrynnikov
- Department of Chemistry, Purdue University, West Lafayette IN 47907, USA
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Livingston DP, Hincha DK, Heyer AG. Fructan and its relationship to abiotic stress tolerance in plants. Cell Mol Life Sci 2009; 66:2007-23. [PMID: 19290476 PMCID: PMC2705711 DOI: 10.1007/s00018-009-0002-x] [Citation(s) in RCA: 194] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2009] [Accepted: 02/04/2009] [Indexed: 01/24/2023]
Abstract
Numerous studies have been published that attempted to correlate fructan concentrations with freezing and drought tolerance. Studies investigating the effect of fructan on liposomes indicated that a direct interaction between membranes and fructan was possible. This new area of research began to move fructan and its association with stress beyond mere correlation by confirming that fructan has the capacity to stabilize membranes during drying by inserting at least part of the polysaccharide into the lipid headgroup region of the membrane. This helps prevent leakage when water is removed from the system either during freezing or drought. When plants were transformed with the ability to synthesize fructan, a concomitant increase in drought and/or freezing tolerance was confirmed. These experiments indicate that besides an indirect effect of supplying tissues with hexose sugars, fructan has a direct protective effect that can be demonstrated by both model systems and genetic transformation.
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Affiliation(s)
- David P Livingston
- USDA and North Carolina State University, 840 Method Road, Unit 3, Raleigh, NC 27695, USA.
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Residual Dipolar Couplings Report on the Active Conformation of Rhodopsin-Bound Protein Fragments. Top Curr Chem (Cham) 2006. [DOI: 10.1007/128_2006_088] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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