1
|
van Aalst EJ, Jang J, Halligan TC, Wylie BJ. Strategies for acquisition of resonance assignment spectra of highly dynamic membrane proteins: a GPCR case study. JOURNAL OF BIOMOLECULAR NMR 2023; 77:191-202. [PMID: 37493866 PMCID: PMC10838152 DOI: 10.1007/s10858-023-00421-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/23/2023] [Accepted: 07/11/2023] [Indexed: 07/27/2023]
Abstract
In protein nuclear magnetic resonance (NMR), chemical shift assignment provides a wealth of information. However, acquisition of high-quality solid-state NMR spectra depends on protein-specific dynamics. For membrane proteins, bilayer heterogeneity further complicates this observation. Since the efficiency of cross-polarization transfer is strongly entwined with protein dynamics, optimal temperatures for spectral sensitivity and resolution will depend not only on inherent protein dynamics, but temperature-dependent phase properties of the bilayer environment. We acquired 1-, 2-, and 3D homo- and heteronuclear experiments of the chemokine receptor CCR3 in a 7:3 phosphatidylcholine:cholesterol lipid environment. 1D direct polarization, cross polarization (CP), and T2' experiments indicate sample temperatures below - 25 °C facilitate higher CP enhancement and longer-lived transverse relaxation times. T1rho experiments indicate intermediate timescales are minimized below a sample temperature of - 20 °C. 2D DCP NCA experiments indicated optimal CP efficiency and resolution at a sample temperature of - 30 °C, corroborated by linewidth analysis in 3D NCACX at - 30 °C compared to - 5 °C. This optimal temperature is concluded to be directly related the lipid phase transition, measured to be between - 20 and 15 °C based on rINEPT signal of all-trans and trans-gauche lipid acyl conformations. Our results have critical implications in acquisition of SSNMR membrane protein assignment spectra, as we hypothesize that different lipid compositions with different phase transition properties influence protein dynamics and therefore the optimal acquisition temperature.
Collapse
Affiliation(s)
- Evan J van Aalst
- Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, TX, 79415, USA
| | - Jun Jang
- Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, TX, 79415, USA
| | - Ty C Halligan
- Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, TX, 79415, USA
| | - Benjamin J Wylie
- Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, TX, 79415, USA.
| |
Collapse
|
2
|
Ruhkopf J, Plachetka U, Moeller M, Pasdag O, Radev I, Peinecke V, Hepp M, Wiktor C, Lohe MR, Feng X, Butz B, Lemme MC. Graphene Coating of Nafion Membranes for Enhanced Fuel Cell Performance. ACS APPLIED ENGINEERING MATERIALS 2023; 1:947-954. [PMID: 37008885 PMCID: PMC10043974 DOI: 10.1021/acsaenm.2c00234] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/02/2022] [Accepted: 02/07/2023] [Indexed: 02/19/2023]
Abstract
Electrochemically exfoliated graphene (e-G) thin films on Nafion membranes exhibit a selective barrier effect against undesirable fuel crossover. This approach combines the high proton conductivity of state-of-the-art Nafion and the ability of e-G layers to effectively block the transport of methanol and hydrogen. Nafion membranes are coated with aqueous dispersions of e-G on the anode side, making use of a facile and scalable spray process. Scanning transmission electron microscopy and electron energy-loss spectroscopy confirm the formation of a dense percolated graphene flake network, which acts as a diffusion barrier. The maximum power density in direct methanol fuel cell (DMFC) operation with e-G-coated Nafion N115 is 3.9 times higher than that of the Nafion N115 reference (39 vs 10 mW cm-2@0.3 V) at a 5M methanol feed concentration. This suggests the application of e-G-coated Nafion membranes for portable DMFCs, where the use of highly concentrated methanol is desirable.
Collapse
Affiliation(s)
- Jasper Ruhkopf
- AMO GmbH, Otto-Blumenthal-Str. 25, 52074 Aachen, Germany
- Chair of Electronic Devices, RWTH Aachen University, Otto-Blumenthal-Str. 2, 52074 Aachen, Germany
| | | | | | - Oliver Pasdag
- The Hydrogen and Fuel Cell Center─ZBT GmbH, Carl-Benz-Str. 201, 47057 Duisburg, Germany
| | - Ivan Radev
- The Hydrogen and Fuel Cell Center─ZBT GmbH, Carl-Benz-Str. 201, 47057 Duisburg, Germany
| | - Volker Peinecke
- The Hydrogen and Fuel Cell Center─ZBT GmbH, Carl-Benz-Str. 201, 47057 Duisburg, Germany
| | - Marco Hepp
- Micro- and Nanoanalytics Group, University of Siegen, Paul-Bonatz-Straße 9-11, 57076 Siegen, Germany
| | - Christian Wiktor
- Micro- and Nanoanalytics Group, University of Siegen, Paul-Bonatz-Straße 9-11, 57076 Siegen, Germany
| | - Martin R. Lohe
- Sixonia Tech GmbH, Maria-Reiche-Str. 3, 01109 Dresden, Germany
| | - Xinliang Feng
- Chair for Molecular Functional Materials, Technische Universität Dresden, Mommsenstr. 4, 01062 Dresden, Germany
| | - Benjamin Butz
- Micro- and Nanoanalytics Group, University of Siegen, Paul-Bonatz-Straße 9-11, 57076 Siegen, Germany
| | - Max C. Lemme
- AMO GmbH, Otto-Blumenthal-Str. 25, 52074 Aachen, Germany
- Chair of Electronic Devices, RWTH Aachen University, Otto-Blumenthal-Str. 2, 52074 Aachen, Germany
| |
Collapse
|
3
|
van Aalst EJ, Borcik CG, Wylie BJ. Spectroscopic signatures of bilayer ordering in native biological membranes. BIOCHIMICA ET BIOPHYSICA ACTA. BIOMEMBRANES 2022; 1864:183891. [PMID: 35217001 PMCID: PMC10793244 DOI: 10.1016/j.bbamem.2022.183891] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/25/2021] [Revised: 02/08/2022] [Accepted: 02/09/2022] [Indexed: 06/14/2023]
Abstract
Membrane proteins and polycyclic lipids like cholesterol and hopanoids coordinate phospholipid bilayer ordering. This phenomenon manifests as partitioning of the liquid crystalline phase into liquid-ordered (Lo) and liquid-disordered (Ld) regions. In Eukaryotes, microdomains are rich in cholesterol and sphingolipids and serve as signal transduction scaffolds. In Prokaryotes, Lo microdomains increase pathogenicity and antimicrobial resistance. Previously, we identified spectroscopically distinct chemical shift signatures for all-trans (AT) and trans-gauche (TG) acyl chain conformations, cyclopropyl ring lipids (CPR), and hopanoids in prokaryotic lipid extracts and used Polarization Transfer (PT) SSNMR to investigate bilayer ordering. To investigate how these findings relate to native bilayer organization, we interrogate whole cell and whole membrane extract samples of Burkholderia thailendensis to investigate bilayer ordering in situ. In 13C-13C 2D SSNMR spectra, we assigned chemical shifts for lipid species in both samples, showing conservation of lipids of interest in our native membrane sample. A one-dimensional temperature series of PT SSNMR and transverse relaxation measurements of AT versus TG acyl conformations in the membrane sample confirm bilayer ordering and a broadened phase transition centered at a lower-than-expected temperature. Bulk protein backbone Cα dynamics and correlations consistent with lipid-protein contacts within are further indicative of microdomain formation and lipid ordering. In aggregate, these findings provide evidence for microdomain formation in vivo and provide insight into phase separation and transition mechanics in biological membranes.
Collapse
Affiliation(s)
- Evan J van Aalst
- Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, TX 79415, USA
| | - Collin G Borcik
- Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, TX 79415, USA
| | - Benjamin J Wylie
- Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, TX 79415, USA.
| |
Collapse
|
4
|
Anisimov YA, Evitts RW, Cree DE, Wilson LD. Polyaniline/Biopolymer Composite Systems for Humidity Sensor Applications: A Review. Polymers (Basel) 2021; 13:2722. [PMID: 34451261 PMCID: PMC8400915 DOI: 10.3390/polym13162722] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2021] [Revised: 08/06/2021] [Accepted: 08/08/2021] [Indexed: 11/18/2022] Open
Abstract
The development of polyaniline (PANI)/biomaterial composites as humidity sensor materials represents an emerging area of advanced materials with promising applications. The increasing attention to biopolymer materials as desiccants for humidity sensor components can be explained by their sustainability and propensity to absorb water. This review represents a literature survey, covering the last decade, which is focused on the interrelationship between the core properties and moisture responsiveness of multicomponent polymer/biomaterial composites. This contribution provides an overview of humidity-sensing materials and the corresponding sensors that emphasize the resistive (impedance) type of PANI devices. The key physicochemical properties that affect moisture sensitivity include the following: swelling, water vapor adsorption capacity, porosity, electrical conductivity, and enthalpies of adsorption and vaporization. Some key features of humidity-sensing materials involve the response time, recovery time, and hysteresis error. This work presents a discussion on various types of humidity-responsive composite materials that contain PANI and biopolymers, such as cellulose, chitosan and structurally related systems, along with a brief overview of carbonaceous and ceramic materials. The effect of additive components, such as polyvinyl alcohol (PVA), for film fabrication and their adsorption properties are also discussed. The mechanisms of hydration and proton transfer, as well as the relationship with conductivity is discussed. The literature survey on hydration reveals that the textural properties (surface area and pore structure) of a material, along with the hydrophile-lipophile balance (HLB) play a crucial role. The role of HLB is important in PANI/biopolymer materials for understanding hydration phenomena and hydrophobic effects. Fundamental aspects of hydration studies that are relevant to humidity sensor materials are reviewed. The experimental design of humidity sensor materials is described, and their relevant physicochemical characterization methods are covered, along with some perspectives on future directions in research on PANI-based humidity sensors.
Collapse
Affiliation(s)
- Yuriy A. Anisimov
- Department of Chemistry, University of Saskatchewan, 110 Science Place (Room 156 Thorvaldson Building), Saskatoon, SK S7N 5C9, Canada;
| | - Richard W. Evitts
- Department of Chemical and Biological Engineering, University of Saskatchewan, 57 Campus Drive, Saskatoon, SK S7N 5A9, Canada;
| | - Duncan E. Cree
- Department of Mechanical Engineering, University of Saskatchewan, 57 Campus Drive, Saskatoon, SK S7N 5A9, Canada
| | - Lee D. Wilson
- Department of Chemistry, University of Saskatchewan, 110 Science Place (Room 156 Thorvaldson Building), Saskatoon, SK S7N 5C9, Canada;
| |
Collapse
|