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Chin SY, Lu Y, Di W, Ye K, Li Z, He C, Cao Y, Tang C, Xue K. Regulating polystyrene glass transition temperature by varying the hydration levels of aromatic ring/Li + interaction. Phys Chem Chem Phys 2023; 25:30223-30227. [PMID: 37817561 DOI: 10.1039/d3cp02995f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/12/2023]
Abstract
Polymer properties can be altered via lithium ion doping, whereby adsorbed Li+ binds with H2O within the polymer chain. However, direct spectroscopic evidence of the tightness of Li+/H2O binding in the solid state is limited, and the impact of Li+ on polymer sidechain packing is rarely reported. Here, we investigate a polystyrene/H2O/LiCl system using solid-state NMR, from which we determined a dipolar coupling of 11.4 kHz between adsorbed Li+ and H2O protons. This coupling corroborates a model whereby Li+ interacts with the oxygen atom in H2O via charge affinity, which we believe is the main driving force of Li+ binding. We demonstrated the impact of hydrated Li+ on sidechain packing and dynamics in polystyrene using proton-detected solid-state NMR. Experimental data and density functional theory (DFT) simulations revealed that the addition of Li+ and the increase in the hydration levels of Li+, coupled with aromatic ring binding, change the energy barrier of sidechain packing and dynamics and, consequently, changes the glass transition temperature of polystyrene.
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Affiliation(s)
- Sze Yuet Chin
- NTU Center of High Field NMR Spectroscopy and Imaging, Nanyang Technological University, 21 Nanyang Link, 637371, Singapore.
| | - Yunpeng Lu
- School of Chemistry, Chemical Engineering and Biotechnology, Nanyang Technological University, 21 Nanyang Link, 637371, Singapore
| | - Weishuai Di
- Collaborative Innovation Center for Advanced Microstructures, National Laboratory of Solid State Microstructure, Department of Physics, Nanjing University, Nanjing 210093, People's Republic of China
| | - Kai Ye
- School of Materials Science and Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore, 639789, Singapore
| | - Zihan Li
- Beijing National Laboratory for Molecular Sciences, College of Chemistry and Molecular Engineering, Peking-Tsinghua Center for life Sciences, Center for Quantitative Biology, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871, China
| | - Chenlu He
- Department of Chemistry, National University of Singapore, Singapore, 117549, Singapore
| | - Yi Cao
- Collaborative Innovation Center for Advanced Microstructures, National Laboratory of Solid State Microstructure, Department of Physics, Nanjing University, Nanjing 210093, People's Republic of China
- Institute for Brain Sciences, Nanjing University, Nanjing 210023, People's Republic of China
| | - Chun Tang
- Beijing National Laboratory for Molecular Sciences, College of Chemistry and Molecular Engineering, Peking-Tsinghua Center for life Sciences, Center for Quantitative Biology, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871, China
| | - Kai Xue
- NTU Center of High Field NMR Spectroscopy and Imaging, Nanyang Technological University, 21 Nanyang Link, 637371, Singapore.
- School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, 637371, Singapore
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Somberg NH, Wu WW, Medeiros-Silva J, Dregni AJ, Jo H, DeGrado WF, Hong M. SARS-CoV-2 Envelope Protein Forms Clustered Pentamers in Lipid Bilayers. Biochemistry 2022; 61:2280-2294. [PMID: 36219675 PMCID: PMC9583936 DOI: 10.1021/acs.biochem.2c00464] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2022] [Revised: 09/26/2022] [Indexed: 11/30/2022]
Abstract
The SARS-CoV-2 envelope (E) protein is a viroporin associated with the acute respiratory symptoms of COVID-19. E forms cation-selective ion channels that assemble in the lipid membrane of the endoplasmic reticulum Golgi intermediate compartment. The channel activity of E is linked to the inflammatory response of the host cell to the virus. Like many viroporins, E is thought to oligomerize with a well-defined stoichiometry. However, attempts to determine the E stoichiometry have led to inconclusive results and suggested mixtures of oligomers whose exact nature might vary with the detergent used. Here, we employ 19F solid-state nuclear magnetic resonance and the centerband-only detection of exchange (CODEX) technique to determine the oligomeric number of E's transmembrane domain (ETM) in lipid bilayers. The CODEX equilibrium value, which corresponds to the inverse of the oligomeric number, indicates that ETM assembles into pentamers in lipid bilayers, without any detectable fraction of low-molecular-weight oligomers. Unexpectedly, at high peptide concentrations and in the presence of the lipid phosphatidylinositol, the CODEX data indicate that more than five 19F spins are within a detectable distance of about 2 nm, suggesting that the ETM pentamers cluster in the lipid bilayer. Monte Carlo simulations that take into account peptide-peptide and peptide-lipid interactions yielded pentamer clusters that reproduced the CODEX data. This supramolecular organization is likely important for E-mediated virus assembly and budding and for the channel function of the protein.
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Affiliation(s)
- Noah H. Somberg
- Department of Chemistry, Massachusetts Institute of Technology, 170 Albany Street, Cambridge, MA 02139
| | - Westley W. Wu
- Department of Chemistry, Massachusetts Institute of Technology, 170 Albany Street, Cambridge, MA 02139
| | - João Medeiros-Silva
- Department of Chemistry, Massachusetts Institute of Technology, 170 Albany Street, Cambridge, MA 02139
| | - Aurelio J. Dregni
- Department of Chemistry, Massachusetts Institute of Technology, 170 Albany Street, Cambridge, MA 02139
| | - Hyunil Jo
- Department of Pharmaceutical Chemistry, 555 Mission Bay Blvd. South, University of California, San Francisco, San Francisco, CA 94158
| | - William F. DeGrado
- Department of Pharmaceutical Chemistry, 555 Mission Bay Blvd. South, University of California, San Francisco, San Francisco, CA 94158
| | - Mei Hong
- Department of Chemistry, Massachusetts Institute of Technology, 170 Albany Street, Cambridge, MA 02139
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Du Y, Su Y. 19F Solid-state NMR characterization of pharmaceutical solids. SOLID STATE NUCLEAR MAGNETIC RESONANCE 2022; 120:101796. [PMID: 35688018 DOI: 10.1016/j.ssnmr.2022.101796] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/09/2022] [Revised: 05/18/2022] [Accepted: 05/19/2022] [Indexed: 06/15/2023]
Abstract
Solid-state NMR has been increasingly recognized as a high-resolution and versatile spectroscopic tool to characterize drug substances and products. However, the analysis of pharmaceutical materials is often carried out at natural isotopic abundance and a relatively low drug loading in multi-component systems and therefore suffers from challenges of low sensitivity. The fact that fluorinated therapeutics are well represented in pipeline drugs and commercial products offers an excellent opportunity to utilize fluorine as a molecular probe for pharmaceutical analysis. We aim to review recent advancements of 19F magic angle spinning NMR methods in modern drug research and development. Applications to polymorph screening at the micromolar level, structural elucidation, and investigation of molecular interactions at the Ångström to submicron resolution in drug delivery, stability, and quality will be discussed.
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Affiliation(s)
- Yong Du
- Analytical Research and Development, Merck & Co., Inc., Rahway, NJ, 07065, United States
| | - Yongchao Su
- Analytical Research and Development, Merck & Co., Inc., Rahway, NJ, 07065, United States; Department of Industrial and Physical Pharmacy, College of Pharmacy, Purdue University, IN, 47907, United States; Division of Molecular Pharmaceutics and Drug Delivery, College of Pharmacy, The University of Texas at Austin, Austin, TX, 78712, United States; Department of Pharmaceutical Sciences, School of Pharmacy, University of Connecticut, Storrs, CT, 06269, United States.
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