1
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Liang L, Xiao L, Yu Z, Liu J. Hexafluoro-2-propanol ( HFIP) decreased LPS-induced inflammatory response of Human microvascular endothelial cells. Asian J Surg 2024:S1015-9584(24)00739-5. [PMID: 38653697 DOI: 10.1016/j.asjsur.2024.04.079] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2024] [Accepted: 04/12/2024] [Indexed: 04/25/2024] Open
Affiliation(s)
- Lei Liang
- Department of Anesthesiology, Zhoushan Women and Children Hospital, Zhoushan, Zhejiang Province, China
| | - Liang Xiao
- Department of Surgery and Oncology, Shenzhen Second People's Hospital, Shenzhen, Guangdong Province, China
| | - Ze Yu
- Laboratory of Cytobiology & Molecular Biology, Zhoushan Hospital, Wenzhou Medical University, Zhoushan, Zhejiang Province, China.
| | - Jia Liu
- School of Agriculture, Sun Yat-sen University, Shenzhen, Guangdong Province, China; Shenzhen Zhongjia Bio-medical Technology Co., LTD, Shenzhen, Guangdong Province, China.
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2
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Peng G, Ullah N, Streiff S, De Oliveira Vigier K, Pera-Titus M, Wischert R, Jérôme F. Metal-Free Selective Synthesis of α,β-Unsaturated Aldehydes from Alkenes and Formaldehyde Catalyzed by Dimethylamine. Chemistry 2024:e202400601. [PMID: 38489225 DOI: 10.1002/chem.202400601] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2024] [Revised: 03/12/2024] [Accepted: 03/14/2024] [Indexed: 03/17/2024]
Abstract
α,β-Unsaturated aldehydes are important building blocks for the synthesis of a wide range of chemicals, including polymers. The synthesis of these molecules from cheap feedstocks such as alkenes remains a scientific challenge, mainly due to the low reactivity of alkenes. Here we report a selective and metal-free access to α,β-unsaturated aldehydes from alkenes with formaldehyde. This reaction is catalyzed by dimethylamine and affords α,β-unsaturated aldehydes in yields of up to 80 %. By combining Density Functional Theory (DFT) calculations and experiments, we elucidate the reaction mechanism which is based on a cascade of hydride transfer, hydrolysis and aldolization reactions. The reaction can be performed under very mild conditions (30-50 °C), in a theoretically 100 % carbon-economical fashion, with water as the only by-product. The reaction was successfully applied to non-activated linear 1-alkenes, thus opening an access to industrially relevant α,β-unsaturated aldehydes from cheap and widely abundant chemicals at large scale.
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Affiliation(s)
- Gongming Peng
- Eco-Efficient Products and Process Laboratory, Syensqo/CNRS 3966 Jin Du Rd., Xin Zhuang Industrial Zone, Shanghai, 201108, China
| | - Naseeb Ullah
- Institut de Chimie des Milieux et Matériaux de Poitiers, University of Poitiers-CNRS, 1 rue Marcel Doré, TSA, 41105, 86073, Poitiers, France
| | - Stéphane Streiff
- Eco-Efficient Products and Process Laboratory, Syensqo/CNRS 3966 Jin Du Rd., Xin Zhuang Industrial Zone, Shanghai, 201108, China
| | - Karine De Oliveira Vigier
- Institut de Chimie des Milieux et Matériaux de Poitiers, University of Poitiers-CNRS, 1 rue Marcel Doré, TSA, 41105, 86073, Poitiers, France
| | - Marc Pera-Titus
- Eco-Efficient Products and Process Laboratory, Syensqo/CNRS 3966 Jin Du Rd., Xin Zhuang Industrial Zone, Shanghai, 201108, China
- Cardiff Catalysis Institute, School of Chemistry, Cardiff University, Main Building, Park Place, Cardiff, CF10 3AT, UK
| | - Raphael Wischert
- Eco-Efficient Products and Process Laboratory, Syensqo/CNRS 3966 Jin Du Rd., Xin Zhuang Industrial Zone, Shanghai, 201108, China
- Syensqo R&I Center Lyon, 85 Av. des Frères Perret, 69190, Saint-Fons, France
| | - François Jérôme
- Institut de Chimie des Milieux et Matériaux de Poitiers, University of Poitiers-CNRS, 1 rue Marcel Doré, TSA, 41105, 86073, Poitiers, France
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3
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Khan S, Ansari B, Ansari NK, Naeem A. Protective role of chlorogenic acid in preserving cytochrome-c stability against HFIP-induced molten globule state at physiological pH. Int J Biol Macromol 2024; 261:129845. [PMID: 38302016 DOI: 10.1016/j.ijbiomac.2024.129845] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2023] [Revised: 01/26/2024] [Accepted: 01/27/2024] [Indexed: 02/03/2024]
Abstract
Numerous neurodegenerative disorders are characterized by protein misfolding and aggregation. The mechanism of protein aggregation is intricate, and it is very challenging to study at cellular level. Inhibition of protein aggregation by interfering with its pathway is one of the ways to prevent neurodegenerative diseases. In the present work, we have evaluated the protective effect of a polyphenol compound chlorogenic acid (CGA) on the native and molten globule state of horse heart cytochrome c (cyt c). A molten globule state of this heme protein was achieved in the presence of fluorinated alcohol 1,1,1,3,3,3-hexafluoroisopropanol (HFIP) at physiological pH, as studied by UV-Vis absorption, circular dichroism, intrinsic and ANS fluorescence. We found that at 50 % (v/v) HFIP, the native cyt c transformed into a molten globule state. The same techniques were also used to analyze the protective effect of CGA on the molten globule state of cyt c, and the results show that the CGA prevented the molten globular state and retained the protein close to the native state at 1:1 protein:CGA sub molar ratio. Molecular dynamics study also revealed that CGA retains the stability of cyt c in HFIP medium by preserving it in an intermediate state close to native conformation.
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Affiliation(s)
- Sadaf Khan
- Department of Biochemistry, Faculty of Life Sciences, Aligarh Muslim University, Aligarh 202002, U.P., India.
| | - Bushra Ansari
- Department of Biochemistry, Faculty of Life Sciences, Aligarh Muslim University, Aligarh 202002, U.P., India
| | - Neha Kausar Ansari
- Department of Biochemistry, Faculty of Life Sciences, Aligarh Muslim University, Aligarh 202002, U.P., India.
| | - Aabgeena Naeem
- Department of Biochemistry, Faculty of Life Sciences, Aligarh Muslim University, Aligarh 202002, U.P., India.
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4
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Casoria M, Macchiagodena M, Rovero P, Andreini C, Papini AM, Cardini G, Pagliai M. Upgrading of the general AMBER force field 2 for fluorinated alcohol biosolvents: A validation for water solutions and melittin solvation. J Pept Sci 2024; 30:e3543. [PMID: 37734745 DOI: 10.1002/psc.3543] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2023] [Revised: 07/16/2023] [Accepted: 08/22/2023] [Indexed: 09/23/2023]
Abstract
The standard GAFF2 force field parameterization has been refined for the fluorinated alcohols 2,2,2-trifluoroethanol (TFE), 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP), and 1,1,1,3,3,3-hexafluoropropan-2-one (HFA), which are commonly used to study proteins and peptides in biomimetic media. The structural and dynamic properties of both proteins and peptides are significantly influenced by the biomimetic environment created by the presence of these cosolvents in aqueous solutions. Quantum mechanical calculations on stable conformers were used to parameterize the atomic charges. Different systems, such as pure liquids, aqueous solutions, and systems formed by melittin protein and cosolvent/water solutions, have been used to validate the new models. The calculated macroscopic and structural properties are in agreement with experimental findings, supporting the validity of the newly proposed models.
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Affiliation(s)
- Michele Casoria
- Dipartimento di Chimica "Ugo Schiff", Università degli Studi di Firenze, Sesto Fiorentino, Italy
- Interdepartmental Research Unit of Peptide and Protein Chemistry and Biology, Università degli Studi di Firenze, Sesto Fiorentino, Italy
| | - Marina Macchiagodena
- Dipartimento di Chimica "Ugo Schiff", Università degli Studi di Firenze, Sesto Fiorentino, Italy
| | - Paolo Rovero
- Interdepartmental Research Unit of Peptide and Protein Chemistry and Biology, Università degli Studi di Firenze, Sesto Fiorentino, Italy
- Department of NeuroFarBa, Università degli Studi di Firenze, Sesto Fiorentino, Italy
| | - Claudia Andreini
- Dipartimento di Chimica "Ugo Schiff", Università degli Studi di Firenze, Sesto Fiorentino, Italy
- Magnetic Resonance Center (CERM), Università degli Studi di Firenze, Sesto Fiorentino, Italy
| | - Anna Maria Papini
- Dipartimento di Chimica "Ugo Schiff", Università degli Studi di Firenze, Sesto Fiorentino, Italy
- Interdepartmental Research Unit of Peptide and Protein Chemistry and Biology, Università degli Studi di Firenze, Sesto Fiorentino, Italy
| | - Gianni Cardini
- Dipartimento di Chimica "Ugo Schiff", Università degli Studi di Firenze, Sesto Fiorentino, Italy
| | - Marco Pagliai
- Dipartimento di Chimica "Ugo Schiff", Università degli Studi di Firenze, Sesto Fiorentino, Italy
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5
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Selke S, Winter M, Finger S, Roeher K, Neppert J, Harth V. A straightforward method for determination of the sevoflurane metabolite hexafluoroisopropanol in urinary occupational medical samples by headspace-gas chromatography mass spectrometry. J Chromatogr B Analyt Technol Biomed Life Sci 2023; 1231:123923. [PMID: 37984163 DOI: 10.1016/j.jchromb.2023.123923] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2023] [Revised: 11/03/2023] [Accepted: 11/04/2023] [Indexed: 11/22/2023]
Abstract
Biological monitoring of the unmodified sevoflurane and its metabolite hexafluoroisopropanol (HFIP) in urine samples was proposed to determine the individual exposure levels of the medical staff. In this study, a method for simultaneous determination of both compounds in urine using static headspace-gas chromatography-mass spectrometry (HS-GC-MS) was developed. The method is linear over a broad concentration range from 1 to 1000 µg/L (r2 > 0.999) and shows high precision. Limits of quantification (LOQ) are 0.6 µg/L for sevoflurane and 3 µg/L for HFIP, representing an excellent sensitivity without the necessity of analyte enrichment. The method was successfully applied in a German pilot-study to monitor both compounds in samples from medical personnel working in operating theatres. Urinary concentrations of HFIP ranged between < LOQ and 145 µg/L, while sevoflurane was below the LOD in all samples.
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Affiliation(s)
- S Selke
- Institute for Occupational and Maritime Medicine (ZfAM), University Medical Center Hamburg-Eppendorf (UKE), Hamburg, Germany.
| | - M Winter
- Institute for Occupational and Maritime Medicine (ZfAM), University Medical Center Hamburg-Eppendorf (UKE), Hamburg, Germany
| | - S Finger
- Institute for Occupational and Maritime Medicine (ZfAM), University Medical Center Hamburg-Eppendorf (UKE), Hamburg, Germany
| | - K Roeher
- University Medical Center Hamburg-Eppendorf (UKE), Department of Anesthesiology, Hamburg, Germany
| | - J Neppert
- University Medical Center Hamburg-Eppendorf (UKE), Department of Anesthesiology, Hamburg, Germany
| | - V Harth
- Institute for Occupational and Maritime Medicine (ZfAM), University Medical Center Hamburg-Eppendorf (UKE), Hamburg, Germany
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6
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Shankar B, Kumar B, Kumar S, Arora A, Kavita, Tomar R, Singh BK. Efficient synthesis of glycosylated imidazo[1,2-a]pyridines via solvent catalysed Groebke-Blackburn-Bienayme reaction. Carbohydr Res 2023; 534:108974. [PMID: 37922684 DOI: 10.1016/j.carres.2023.108974] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2023] [Revised: 09/13/2023] [Accepted: 10/10/2023] [Indexed: 11/07/2023]
Abstract
A solvent catalysed and metal catalyst-free Groebke-Blackburn-Bienayame three component reaction (GBB-3CR) has been developed for the synthesis of 2-(β-D-glycal-1-yl)-3-N-alkylamino-1-azaindolizines and 2-alkyl/aryl/heteroaryl-3-N-alkylamino-1-azaindolizines. The modified GBB reaction protocol is highly efficient, versatile, atom economic and has been performed in hexafluoroisopropanol (HFIP) without any added catalyst. The GBB-3CR showed high tolerance for a large no of substrates in term of aldehydes, differently substituted 2-aminopyridines and isocyanides without being affected by the presence of electron donating and electron withdrawing substituents at either aldehydes or 2-aminopyridines.
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Affiliation(s)
- Bhawani Shankar
- Department of Chemistry, Deshbandhu College, University of Delhi, Delhi, 110019, India; Bioorganic Laboratory, Department of Chemistry, University of Delhi, Delhi, 110007, India.
| | - Banty Kumar
- Department of Chemistry, Rajdhani College, University of Delhi, Delhi, 110015, India
| | - Sumit Kumar
- Bioorganic Laboratory, Department of Chemistry, University of Delhi, Delhi, 110007, India
| | - Aditi Arora
- Bioorganic Laboratory, Department of Chemistry, University of Delhi, Delhi, 110007, India
| | - Kavita
- Bioorganic Laboratory, Department of Chemistry, University of Delhi, Delhi, 110007, India
| | - Rashmi Tomar
- Department of Chemistry, M.S.J. College, Bharatpur, Rajasthan, 321001, India
| | - Brajendra K Singh
- Bioorganic Laboratory, Department of Chemistry, University of Delhi, Delhi, 110007, India
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7
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Gao J, Liu Z, Guo X, Wu L, Chen Z, Yang K. 1,1,1,3,3,3-Hexafluoro-2-Propanol-Promoted Friedel-Crafts Reaction: Metal-Free Synthesis of C3-Difluoromethyl Carbinol-Containing Imidazo[1,2- a]pyridines at Room Temperature. Molecules 2023; 28:7522. [PMID: 38005245 PMCID: PMC10672982 DOI: 10.3390/molecules28227522] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2023] [Revised: 11/06/2023] [Accepted: 11/08/2023] [Indexed: 11/26/2023] Open
Abstract
A facile and efficient method has been developed for the synthesis of C3-difluoromethyl carbinol-containing imidazo[1,2-a]pyridines at room temperature via the HFIP-promoted Friedel-Crafts reaction of difluoroacetaldehyde ethyl hemiacetal and imidazo[1,2-a]pyridines. This strategy could be applied to the direct C(sp2)-H hydroxydifluoromethylation of imidazo[1,2-a]pyridines and afford a series of novel difluoromethylated carbinols in good to satisfactory yields with 29 examples. Furthermore, gram-scale and synthetic transformation experiments have also been achieved, demonstrating its potential applicable value in organic synthesis. This green protocol has several advantages, including being transition metal- and oxidant-free, being carried out at room temperature, having high efficiency, and having a wide substrate scope.
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Affiliation(s)
| | | | | | | | - Zhixi Chen
- College of Pharmacy, Gannan Medical University, Ganzhou 341000, China; (J.G.); (Z.L.); (X.G.); (L.W.)
| | - Kai Yang
- College of Pharmacy, Gannan Medical University, Ganzhou 341000, China; (J.G.); (Z.L.); (X.G.); (L.W.)
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8
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Hu X, Zhao X, Lv X, Wu YB, Bu Y, Lu G. Ab Initio Metadynamics Simulations of Hexafluoroisopropanol Solvent Effects: Synergistic Role of Solvent H-Bonding Networks and Solvent-Solute C-H/π Interactions. Chemistry 2023; 29:e202203879. [PMID: 36575142 DOI: 10.1002/chem.202203879] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2022] [Accepted: 12/27/2022] [Indexed: 12/29/2022]
Abstract
The solvent effects in Friedel-Crafts cycloalkylation of epoxides and Cope rearrangement of aldimines were investigated by using ab initio molecular dynamics simulations. Explicit molecular treatments were applied for both reactants and solvents. The reaction mechanisms were elucidated via free energy calculations based on metadynamics simulations. The results reveal that both reactions proceed in a concerted fashion. Key solvent-substrate interactions are identified from the structures of transition states with explicit solvent molecules. The remarkable promotion effect of hexafluoroisopropanol solvent is ascribed to the synergistic effect of H-bonding networks and C-H/π interactions with substrates.
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Affiliation(s)
- Xinmin Hu
- School of Chemistry and Chemical Engineering, Key Laboratory of Colloid and Interface Chemistry, Ministry of Education, Shandong University, Jinan, Shandong, 250100, P. R. China
| | - Xia Zhao
- School of Chemistry and Chemical Engineering, Key Laboratory of Colloid and Interface Chemistry, Ministry of Education, Shandong University, Jinan, Shandong, 250100, P. R. China
| | - Xiangying Lv
- School of Chemistry and Chemical Engineering, Key Laboratory of Colloid and Interface Chemistry, Ministry of Education, Shandong University, Jinan, Shandong, 250100, P. R. China
| | - Yan-Bo Wu
- Key Lab for Materials of Energy Conversion and Storage of Shanxi Province, and Key Lab of Chemical Biology and Molecular Engineering of Ministry of Education, Institute of Molecular Science, Shanxi University, Taiyuan, Shanxi, 030006, P. R. China
| | - Yuxiang Bu
- School of Chemistry and Chemical Engineering, Key Laboratory of Colloid and Interface Chemistry, Ministry of Education, Shandong University, Jinan, Shandong, 250100, P. R. China
| | - Gang Lu
- School of Chemistry and Chemical Engineering, Key Laboratory of Colloid and Interface Chemistry, Ministry of Education, Shandong University, Jinan, Shandong, 250100, P. R. China
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9
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Aynetdinova D, Jacques R, Christensen KE, Donohoe TJ. Alcohols as Efficient Intermolecular Initiators for a Highly Stereoselective Polyene Cyclisation Cascade. Chemistry 2023; 29:e202203732. [PMID: 36478469 PMCID: PMC10946764 DOI: 10.1002/chem.202203732] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2022] [Revised: 12/01/2022] [Accepted: 12/05/2022] [Indexed: 12/12/2022]
Abstract
The use of benzylic and allylic alcohols in HFIP solvent together with Ti(Oi Pr)4 has been shown to trigger a highly stereoselective polyene cyclisation cascade. Three new carbon-carbon bonds are made during the process and complete stereocontrol of up to five new stereogenic centers is observed. The reaction is efficient, has high functional group tolerance and is atom-economic generating water as a stoichiometric by-product. A new polyene substrate-class is employed, and subsequent mechanistic studies indicate a stereoconvergent mechanism. The products of this reaction can be used to synthesize steroid-analogues in a single step.
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Affiliation(s)
- Daniya Aynetdinova
- Department of ChemistryUniversity of OxfordChemistry Research LaboratoryOxfordOX1 3TAUK
| | - Reece Jacques
- Early Chemical Development, Medicinal Chemistry R&DVertex PharmaceuticalsAbingtonOX14 4RWUK
| | | | - Timothy J. Donohoe
- Department of ChemistryUniversity of OxfordChemistry Research LaboratoryOxfordOX1 3TAUK
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10
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Park OS, Bang JK, Cheong C, Jeon YH. Structure of AQEE-30 of VGF Neuropeptide in Membrane-Mimicking Environments. Int J Mol Sci 2022; 23:ijms232213953. [PMID: 36430431 PMCID: PMC9696787 DOI: 10.3390/ijms232213953] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2022] [Revised: 11/07/2022] [Accepted: 11/07/2022] [Indexed: 11/16/2022] Open
Abstract
AQEE-30 is one of the VGF peptides, which are derived from the VGF polypeptide precursor, and related to various physiological phenomena including neuroprotective effects in Huntington's disease and amyotrophic lateral sclerosis (ALS). Although various functions of AQEE-30 have been reported so far, the structure of this peptide has not been reported yet. In this study, the structure of human AQEE-30 was investigated in hexafluoroisopropanol (HFIP) and dodecyl phosphocholine (DPC) micelle solutions, using circular dichroism (CD) and nuclear magnetic resonance (NMR) spectroscopy. CD results showed that AQEE-30 had a partial helical structure in aqueous buffer, and the helical structure was stabilized in the HFIP and DPC micelle solutions. The 3D structures determined by NMR spectroscopy showed that AQEE-30 adopted mainly α-helical structure in both the HFIP and DPC micelle solutions. The surface of AQEE-30 showed that it was predominantly negatively charged. The residues from 601 to 611 in both the HFIP and DPC micelle solutions showed amphiphilicity with four negatively charged residues, glutamate. The C-terminal consecutive arginine residues formed a partial positively charged surface. These results suggest an α-helical active structure of AQEE-30 in the cell-membrane environment.
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Affiliation(s)
- One-Sung Park
- College of Pharmacy, Korea University Sejong Campus, Sejong 30019, Korea
- Division of Bioconvergence Analysis, Korea Basic Science Institute, Cheongju 28119, Korea
| | - Jeong-Kyu Bang
- Division of Bioconvergence Analysis, Korea Basic Science Institute, Cheongju 28119, Korea
| | - Chaejoon Cheong
- Division of Bioconvergence Analysis, Korea Basic Science Institute, Cheongju 28119, Korea
- Department of Bioanalytical Sciences, University of Science and Technology, Cheongju 28119, Korea
- Correspondence: (C.C.); (Y.-H.J.)
| | - Young-Ho Jeon
- College of Pharmacy, Korea University Sejong Campus, Sejong 30019, Korea
- Correspondence: (C.C.); (Y.-H.J.)
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11
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Abe T, Yamashiro T, Shimizu K, Sawada D. Indole Editing Enabled by HFIP-Mediated Ring-Switch Reactions of 3-Amino-2-Hydroxyindolines. Chemistry 2022; 28:e202201113. [PMID: 35438809 DOI: 10.1002/chem.202201113] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2022] [Indexed: 12/26/2022]
Abstract
This work reports the novel reactivity of hemiaminal as a precursor for indole editing at the multi-site. The HFIP-promoted indole editing of indoline hemiaminals affords 2-arylindoles through a ring-switch sequence. The key to success of this transformation is to use a cyclic hemiaminal as an α-amino aldehyde surrogate under transient tautomeric control. This transformation features mild reaction conditions and good yields with broad functional group tolerance. The utility of this transformation is presented through the one-pot protocol and the synthesis of isocryptolepine.
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Affiliation(s)
- Takumi Abe
- Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, 1-1-1 Tsushima-naka, Kita-ku, Okayama, 7008530, Japan
| | - Toshiki Yamashiro
- Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, 1-1-1 Tsushima-naka, Kita-ku, Okayama, 7008530, Japan
| | - Kaho Shimizu
- Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, 1-1-1 Tsushima-naka, Kita-ku, Okayama, 7008530, Japan
| | - Daisuke Sawada
- Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, 1-1-1 Tsushima-naka, Kita-ku, Okayama, 7008530, Japan
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12
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Anh To T, Pei C, Koenigs RM, Vinh Nguyen T. Hydrogen Bonding Networks Enable Brønsted Acid-Catalyzed Carbonyl-Olefin Metathesis. Angew Chem Int Ed Engl 2022; 61:e202117366. [PMID: 34985790 PMCID: PMC9303705 DOI: 10.1002/anie.202117366] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2021] [Indexed: 12/18/2022]
Abstract
Synthetic chemists have learned to mimic nature in using hydrogen bonds and other weak interactions to dictate the spatial arrangement of reaction substrates and to stabilize transition states to enable highly efficient and selective reactions. The activation of a catalyst molecule itself by hydrogen‐bonding networks, in order to enhance its catalytic activity to achieve a desired reaction outcome, is less explored in organic synthesis, despite being a commonly found phenomenon in nature. Herein, we show our investigation into this underexplored area by studying the promotion of carbonyl‐olefin metathesis reactions by hydrogen‐bonding‐assisted Brønsted acid catalysis, using hexafluoroisopropanol (HFIP) solvent in combination with para‐toluenesulfonic acid (pTSA). Our experimental and computational mechanistic studies reveal not only an interesting role of HFIP solvent in assisting pTSA Brønsted acid catalyst, but also insightful knowledge about the current limitations of the carbonyl‐olefin metathesis reaction.
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Affiliation(s)
- Tuong Anh To
- School of Chemistry, University of New South Wales, Sydney Anzac Parade, Kensington, NSW, 2052, Australia
| | - Chao Pei
- Institute of Organic Chemistry, RWTH Aachen, Landoltweg 1, 52074, Aachen, Germany
| | - Rene M Koenigs
- Institute of Organic Chemistry, RWTH Aachen, Landoltweg 1, 52074, Aachen, Germany
| | - Thanh Vinh Nguyen
- School of Chemistry, University of New South Wales, Sydney Anzac Parade, Kensington, NSW, 2052, Australia
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13
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Ghosh S, Qu ZW, Pradhan S, Ghosh A, Grimme S, Chatterjee I. HFIP-Assisted Single C-F Bond Activation of Trifluoromethyl Ketones using Visible-Light Photoredox Catalysis. Angew Chem Int Ed Engl 2021; 61:e202115272. [PMID: 34821454 DOI: 10.1002/anie.202115272] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2021] [Indexed: 11/07/2022]
Abstract
A visible light photoredox catalytic method for the selective cleavage of single strong C-F bond in trifluoromethyl ketones is reported. Single electron reduction of trifluoromethyl ketones generates difluoromethyl radicals which can be engaged in intermolecular C-C bond formation with N-methyl-N-arylmethacrylamides to furnish fluorine-containing oxindole derivatives in good yields. The reaction shows excellent chemoselectivity with good functional group tolerance under mild conditions. 1,1,1,3,3,3-Hexafluoroisopropanol (HFIP) as a solvent plays a critical role for the selective single C-F bond cleavage. High-level DFT calculations are depicted to shed light on the mechanism.
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Affiliation(s)
- Soumen Ghosh
- Department of Chemistry, Indian Institute of Technology Ropar, Nangal Road, Rupnagar, Punjab, 140001, India
| | - Zheng-Wang Qu
- Mulliken Center for Theoretical Chemistry, Institut für Physikalische und Theoretische Chemie, Rheinische Friedrich-Wilhelms-Universität Bonn, Beringstrasse 4, 53115, Bonn, Germany
| | - Suman Pradhan
- Department of Chemistry, Indian Institute of Technology Ropar, Nangal Road, Rupnagar, Punjab, 140001, India
| | - Avisek Ghosh
- Department of Chemistry, Indian Institute of Technology Ropar, Nangal Road, Rupnagar, Punjab, 140001, India
| | - Stefan Grimme
- Mulliken Center for Theoretical Chemistry, Institut für Physikalische und Theoretische Chemie, Rheinische Friedrich-Wilhelms-Universität Bonn, Beringstrasse 4, 53115, Bonn, Germany
| | - Indranil Chatterjee
- Department of Chemistry, Indian Institute of Technology Ropar, Nangal Road, Rupnagar, Punjab, 140001, India
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14
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Lu L, Hua R. Dual XH-π Interaction of Hexafluoroisopropanol with Arenes. Molecules 2021; 26:4558. [PMID: 34361719 DOI: 10.3390/molecules26154558] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2021] [Revised: 07/23/2021] [Accepted: 07/26/2021] [Indexed: 11/17/2022] Open
Abstract
The dual XH (OH and CH) hydrogen-bond-donating property of 1,1,1,3,3,3-hexafluoroisopropanol (HFIP) and the strong dual XH-π interaction with arenes were firstly disclosed by theoretical studies. Here, the high accuracy post-Hartree-Fock methods, CCSD(T)/CBS, reveal the interaction energy of HFIP/benzene complex (-7.22 kcal/mol) and the contribution of the electronic correlation energy in the total interaction energy. Strong orbital interaction between HFIP and benzene was found by using the DFT method in this work to disclose the dual XH-π intermolecular orbital interaction of HFIP with benzene-forming bonding and antibonding orbitals resulting from the orbital symmetry of HFIP. The density of states and charge decomposition analyses were used to investigate the orbital interactions. Isopropanol (IP), an analogue of HFIP, and chloroform (CHCl3) were studied to compare them with the classical OH-π, and non-classical CH-π interactions. In addition, the influence of the aggregating effect of HFIP, and the numbers of substituted methyl groups in benzene rings were also studied. The interaction energies of HFIP with the selected 24 common organic compounds were calculated to understand the role of HFIP as solvent or additive in organic transformation in a more detailed manner. A single-crystal X-ray diffraction study of hexafluoroisopropyl benzoate further disclosed and confirmed that the CH of HFIP shows the non-classical hydrogen-bond-donating behavior.
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15
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Rodríguez JF, Zhang A, Bajohr J, Whyte A, Mirabi B, Lautens M. Cycloisomerization of Carbamoyl Chlorides in Hexafluoroisopropanol: Stereoselective Synthesis of Chlorinated Methylene Oxindoles and Quinolinones. Angew Chem Int Ed Engl 2021; 60:18478-18483. [PMID: 34157191 DOI: 10.1002/anie.202103323] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2021] [Revised: 05/24/2021] [Indexed: 12/20/2022]
Abstract
Hexafluoroisopropanol (HFIP) was employed as an additive for the generation of 3-(chloromethylene)oxindoles via the chloroacylation of alkyne-tethered carbamoyl chlorides. This reaction avoids the use of a metal catalyst and accesses products in high yields and stereoselectivities. Additionally, this reaction is scalable and proved amenable to a series of product derivatizations, including the synthesis of nintedanib. The reactivity of alkene-tethered carbamoyl chlorides with hexafluoroisopropanol (HFIP) was harnessed towards the synthesis of 2-quinolinones.
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Affiliation(s)
- José F Rodríguez
- Davenport Research Laboratories, Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, Ontario, M5S 3H6, Canada
| | - Anji Zhang
- Davenport Research Laboratories, Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, Ontario, M5S 3H6, Canada
| | - Jonathan Bajohr
- Davenport Research Laboratories, Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, Ontario, M5S 3H6, Canada
| | - Andrew Whyte
- Davenport Research Laboratories, Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, Ontario, M5S 3H6, Canada
| | - Bijan Mirabi
- Davenport Research Laboratories, Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, Ontario, M5S 3H6, Canada
| | - Mark Lautens
- Davenport Research Laboratories, Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, Ontario, M5S 3H6, Canada
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16
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Hasan S, Isar M, Naeem A. Macromolecular crowding stabilises native structure of α-chymotrypsinogen-A against hexafluoropropanol-induced aggregates. Int J Biol Macromol 2020; 164:3780-3788. [PMID: 32835802 DOI: 10.1016/j.ijbiomac.2020.08.149] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2020] [Revised: 08/06/2020] [Accepted: 08/19/2020] [Indexed: 12/20/2022]
Abstract
Cell interior is extremely congested with tightly packed biological macromolecules that exerts macromolecular crowding effect, influencing biophysical properties of proteins. To have a deeper insight into it we studied consequences of crowding on aggregation susceptibility and structural stability of α-chymotrypsinogen-A, pro-enzyme of serine protease family, upon addition of co-solvent reported to exert stress on polypeptides crafting favourable conditions for aggregation. Hexafluoropropan-2-ol (HFIP), a fluorinated alcohol caused structural disruption at 5% v/v unveiled by reduced intrinsic intensity and blue shifted ANS spectra. Significantly enhanced, red-shifted ThT and Congo red spectra sustained conformational changes concomitant with aggregation. FTIR and CD results confirmed transition of native structure to non-native extended, cross-linked beta-sheets. Transmission electron micrographs visibly exhibited incidence of amorphous aggregates. Macromolecular crowding, typically mimicked by concentrated solutions of dextran 70, was noticeably witnessed to defend conformational stability under denaturing condition. The native structure was retained maximally in presence of 100 mg/ml followed by 200 and 300 mg/ml dextran indicating concentration dependent deceleration of aggregate formation. It can be established that explicit consideration of crowding effects using relevant range of inert crowding agents must be a requisite for presumptions on intracellular conformational behaviour of proteins deduced from in vitro experiments.
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Affiliation(s)
- Samra Hasan
- Department of Biochemistry, Faculty of Life Sciences, Aligarh Muslim University, Aligarh, 202002, U.P., India
| | - Mohd Isar
- Department of Biochemistry, Faculty of Life Sciences, Aligarh Muslim University, Aligarh, 202002, U.P., India
| | - Aabgeena Naeem
- Department of Biochemistry, Faculty of Life Sciences, Aligarh Muslim University, Aligarh, 202002, U.P., India.
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17
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Li Z, Yu B. HFIP-Promoted de Novo Synthesis of Biologically Relevant Nonnatural α-Arylated Amino Esters and Dipeptide Mimetics. Chemistry 2019; 25:16528-16532. [PMID: 31617627 DOI: 10.1002/chem.201904395] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2019] [Revised: 10/15/2019] [Indexed: 01/24/2023]
Abstract
Amino acids are fundamental building blocks, which have been extensively used in drug design and organic synthesis. However, nonnatural amino acids are relatively less studied. In this work, the authors report the first HFIP-promoted de novo synthesis of nonnatural α-arylated amino esters and dipeptide mimetics (27 examples, up to 99 % yield) from readily available amines, ethyl glyoxylate and electron-rich arenes under mild conditions, in which one C-C bond, one C-N bond and one chiral center were established simultaneously. The reaction was also performed on a gram scale, giving compound 4 a in 96 % yield. In addition, this protocol was successfully applied to the late-stage elaboration of drug molecules, such as tranylcypromine (TCP or PCPA) and troxipide. Interestingly, compound 4 h inactivated histone lysine specific demethylase 1 (LSD1) potently with an IC50 value of 0.296 μm. To the best of our knowledge, compound 4 h is the first LSD1 inhibitor derived from nonnatural α-arylated amino esters, and therefore could be used as a hit compound for the development of new LSD1 inhibitors. The synthesized nonnatural α-arylated amino esters and dipeptide mimetics as unique building blocks may have potential synthetic utilities.
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Affiliation(s)
- Zhonghua Li
- Scientific Research Center & Laboratory Animal Center, Henan University of Chinese Medicine, 156 Jinshui East Road, 450046, Zhengzhou, Henan, P. R. China
| | - Bin Yu
- School of Pharmaceutical Sciences, Zhengzhou University, 100 Science Avenue, 450001, Zhengzhou, Henan, P. R. China.,State Key Laboratory of Pharmaceutical Biotechnology, Nanjing University, Nanjing, 210023, P. R. China
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18
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Veigure R, Lossmann K, Hecht M, Parman E, Born R, Leito I, Herodes K, Kipper K. Retention of acidic and basic analytes in reversed phase column using fluorinated and novel eluent additives for liquid chromatography-tandem mass spectrometry. J Chromatogr A 2020; 1613:460667. [PMID: 31708217 DOI: 10.1016/j.chroma.2019.460667] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2019] [Revised: 10/24/2019] [Accepted: 10/29/2019] [Indexed: 12/11/2022]
Abstract
This research focuses on retention mechanisms in a LC column with C18 stationary phase when novel eluent additives (HFIP, HFTB and TFE as well as NFTB and perfluoropinacol) are used. The retention factors between novel eluent additives and conventional ones like ammonium acetate and ammonium bicarbonate at different eluent pH values were compared. A simple set of drug-like molecules, widely spread over different logP values, containing protonated and deprotonated acids and bases was selected for this investigation. HFIP, HFTB, NFTB and PP demonstrated strong influence on basic polar analytes in basic medium. These additives drastically increased retention. A decrease in retention was observed for acidic analytes when novel eluent additives were used. Additionally, for the first time, the absolute pH (pHabs) scale was used for expressing the mobile phase pH.
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Tschirner S, Weingart E, Teevs L, Prüße U. Catalytic Dehydration of Fructose to 5-Hydroxymethylfurfural (HMF) in Low-Boiling Solvent Hexafluoroisopropanol ( HFIP). Molecules 2018; 23:E1866. [PMID: 30050015 PMCID: PMC6222439 DOI: 10.3390/molecules23081866] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2018] [Revised: 07/17/2018] [Accepted: 07/23/2018] [Indexed: 12/05/2022] Open
Abstract
A mixture of hexafluoroisopropanol (HFIP) and water was used as a new and unknown monophasic reaction solvent for fructose dehydration in order to produce HMF. HFIP is a low-boiling fluorous alcohol (b.p. 58 °C). Hence, HFIP can be recovered cost efficiently by distillation. Different ion-exchange resins were screened for the HFIP/water system in batch experiments. The best results were obtained for acidic macroporous ion-exchange resins, and high HMF yields up to 70% were achieved. The effects of various reaction conditions like initial fructose concentration, catalyst concentration, water content in HFIP, temperature and influence of the catalyst particle size were evaluated. Up to 76% HMF yield was attained at optimized reaction conditions for high initial fructose concentration of 0.5 M (90 g/L). The ion-exchange resin can simply be recovered by filtration and reused several times. This reaction system with HFIP/water as solvent and the ion-exchange resin Lewatit K2420 as catalyst shows excellent performance for HMF synthesis.
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Affiliation(s)
- Sarah Tschirner
- Thünen Institute of Agricultural Technology, Bundesallee 47, 38116 Braunschweig, Germany.
| | - Eric Weingart
- Thünen Institute of Agricultural Technology, Bundesallee 47, 38116 Braunschweig, Germany.
| | - Linda Teevs
- Thünen Institute of Agricultural Technology, Bundesallee 47, 38116 Braunschweig, Germany.
| | - Ulf Prüße
- Thünen Institute of Agricultural Technology, Bundesallee 47, 38116 Braunschweig, Germany.
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20
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Weingart E, Tschirner S, Teevs L, Prüße U. Conversion of Fructose to HMF in a Continuous Fixed Bed Reactor with Outstanding Selectivity. Molecules 2018; 23:E1802. [PMID: 30037031 PMCID: PMC6099769 DOI: 10.3390/molecules23071802] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2018] [Revised: 07/12/2018] [Accepted: 07/18/2018] [Indexed: 12/04/2022] Open
Abstract
5-Hydroxymethylfurfural (HMF) is a very promising component for bio-based plastics. Efficient synthesis of HMF from biomass is still challenging because of fast degradation of HMF to by-products under formation conditions. Therefore, different studies, conducted mainly in monophasic and biphasic batch systems with and without water addition have been published and are still under investigation. However, to produce HMF at a large scale, a continuous process is preferable. Until now, only a few studies have been published in this context. In this work, it is shown that fluorous alcohol hexafluoroisopropanol (HFIP) can act as superior reaction solvent for HMF synthesis from fructose in a fixed bed reactor. Very high yields of 76% HMF can be achieved in this system under optimized conditions, whilst the catalyst is very stable over several days. Such high yields are only described elsewhere with high boiling reaction solvents like dimethylsulfoxide (DMSO), whereas HFIP with a boiling point of 58 °C is very easy to separate from HMF.
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Affiliation(s)
- Eric Weingart
- Thuenen Institute of Agricultural Technology, Bundesallee 47, 38116 Braunschweig, Germany.
| | - Sarah Tschirner
- Thuenen Institute of Agricultural Technology, Bundesallee 47, 38116 Braunschweig, Germany.
| | - Linda Teevs
- Thuenen Institute of Agricultural Technology, Bundesallee 47, 38116 Braunschweig, Germany.
| | - Ulf Prüße
- Thuenen Institute of Agricultural Technology, Bundesallee 47, 38116 Braunschweig, Germany.
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21
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Sung Y, Eliezer D. Structure and dynamics of the extended-helix state of alpha-synuclein: Intrinsic lability of the linker region. Protein Sci 2018; 27:1314-1324. [PMID: 29663556 PMCID: PMC6032355 DOI: 10.1002/pro.3426] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2018] [Revised: 04/11/2018] [Accepted: 04/12/2018] [Indexed: 12/25/2022]
Abstract
The Parkinson's protein alpha-synuclein binds to synaptic vesicles in vivo and adopts a highly extended helical conformation when binding to lipid vesicles in vitro. High-resolution structural analysis of alpha-synuclein bound to small lipid or detergent micelles revealed two helices connected by a non-helical linker, but corresponding studies of the vesicle-bound extended-helix state are hampered by the size and heterogeneity of the protein-vesicle complex. Here we employ fluorinated alcohols (FAs) to induce a highly helical aggregation-resistant state of alpha-synuclein in solution that resembles the vesicle-bound extended-helix state but is amenable to characterization using high-resolution solution-state NMR. Analysis of chemical shift, NOE, coupling constant, PRE and relaxation measurements shows that the lipid-binding domain of alpha-synuclein in FA solutions indeed adopts a single continuous helix and that the ends of this helix do not come into detectable proximity to each other. The helix is well ordered in the center, but features an increase in fast internal motions suggestive of helix fraying approaching the termini. The central region of the helix exhibits slower time scale motions that likely result from flexing of the highly anisotropic structure. Importantly, weak or missing short- and intermediate-range NOEs in the region corresponding to the non-helical linker of micelle-bound alpha-synuclein indicate that the helical structure in this region of the protein is intrinsically unstable. This suggests that conversion of alpha-synuclein from the extended-helix to the broken-helix state represents a functionally relevant structural transition.
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Affiliation(s)
- Yoon‐Hui Sung
- Department of Biochemistry and Program in Structural BiologyWeill Cornell MedicineNew YorkNew York
| | - David Eliezer
- Department of Biochemistry and Program in Structural BiologyWeill Cornell MedicineNew YorkNew York
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22
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Sobieski BJ, Noda I, Rabolt JF, Chase DB. Observation of Intermolecular Hydrogen Bonding Interactions in Biosynthesized and Biodegradable Poly [(R)-3-hydroxybutyrate- co-(R)-3-hydroxyhexanoate] in Chloroform and 1,1,1,3,3,3-Hexafluoro-2-propanol ( HFIP). Appl Spectrosc 2017; 71:2339-2343. [PMID: 28441032 DOI: 10.1177/0003702817702154] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
In this work, we describe polymer-solvent interactions in biosynthesized and biodegradable poly[(R)-3-hydroxybutyrate- co-(R)-3-hydroxyhexanoate] (PHBHx) and the atactic homopolymer, poly(3-hydroxybutyrate) (a-PHB), which were studied both as neat polymers and in solutions of chloroform and 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP). Specifically, infrared frequency shifts of the carbonyl band were observed in semi-crystalline PHBHx, but not in a-PHB, because it cannot form the helical conformation required for crystallization. The carbonyl band of PHBHx exhibited the high frequency associated with amorphous structure in chloroform and the lower frequency traditionally attributed to the helical crystalline structure in HFIP. The same results were obtained for a-PHB, demonstrating that the helical structure is not required for a lower frequency carbonyl-stretching mode. It is proposed that the band shift is due to hydrogen bonding between the carbonyl and hydroxyl hydrogen in HFIP. Therefore, the carbonyl frequency observed upon crystallization is most likely due to hydrogen bonding between the carbonyl and methyl hydrogen of the neighboring polymer chain in the crystal lattice as previously suggested.
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Affiliation(s)
- Brian J Sobieski
- 1 Department of Materials Science and Engineering, University of Delaware, Newark, DE, USA
- 2 FXI Inc., Aston, PA, USA
| | - Isao Noda
- 1 Department of Materials Science and Engineering, University of Delaware, Newark, DE, USA
- 3 Danimer Scientific., Bainbridge, GA, USA
| | - John F Rabolt
- 1 Department of Materials Science and Engineering, University of Delaware, Newark, DE, USA
| | - D Bruce Chase
- 1 Department of Materials Science and Engineering, University of Delaware, Newark, DE, USA
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23
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Shigemitsu Y, Iwaya N, Goda N, Matsuzaki M, Tenno T, Narita A, Hoshi M, Hiroaki H. Nuclear magnetic resonance evidence for the dimer formation of beta amyloid peptide 1-42 in 1,1,1,3,3,3-hexafluoro-2-propanol. Anal Biochem 2016; 498:59-67. [PMID: 26772162 DOI: 10.1016/j.ab.2015.12.021] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2015] [Revised: 12/04/2015] [Accepted: 12/29/2015] [Indexed: 01/05/2023]
Abstract
Alzheimer's disease involves accumulation of senile plaques in which filamentous aggregates of amyloid beta (Aβ) peptides are deposited. Recent studies demonstrate that oligomerization pathways of Aβ peptides may be complicated. To understand the mechanisms of Aβ(1-42) oligomer formation in more detail, we have established a method to produce (15)N-labeled Aβ(1-42) suited for nuclear magnetic resonance (NMR) studies. For physicochemical studies, the starting protein material should be solely monomeric and all Aβ aggregates must be removed. Here, we succeeded in fractionating a "precipitation-resistant" fraction of Aβ(1-42) from an "aggregation-prone" fraction by high-performance liquid chromatography (HPLC), even from bacterially overexpressed Aβ(1-42). However, both Aβ(1-42) fractions after 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP) treatment formed amyloid fibrils. This indicates that the "aggregation seed" was not completely monomerized during HFIP treatment. In addition, Aβ(1-42) dissolved in HFIP was found to display a monomer-dimer equilibrium, as shown by two-dimensional (1)H-(15)N NMR. We demonstrated that the initial concentration of Aβ during the HFIP pretreatment altered the kinetic profiles of Aβ fibril formation in a thioflavin T fluorescence assay. The findings described here should ensure reproducible results when studying the Aβ(1-42) peptide.
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Motiwala HF, Yin Q, Aubé J. Improved Schmidt Conversion of Aldehydes to Nitriles Using Azidotrimethylsilane in 1,1,1,3,3,3-Hexafluoro-2-propanol. Molecules 2015; 21:E45. [PMID: 26729081 PMCID: PMC6273554 DOI: 10.3390/molecules21010045] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2015] [Revised: 12/16/2015] [Accepted: 12/22/2015] [Indexed: 12/05/2022] Open
Abstract
The Schmidt reaction of aromatic aldehydes using a substoichiometric amount (40 mol %) of triflic acid is described. Low catalyst loading was enabled by a strong hydrogen-bond-donating solvent hexafluoro-2-propanol (HFIP). This improved protocol tolerates a broad scope of aldehydes with diverse functional groups and the corresponding nitriles were obtained in good to high yields without the need for aqueous work up.
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Affiliation(s)
- Hashim F Motiwala
- Department of Medicinal Chemistry, Delbert M. Shankel Structural Biology Center, University of Kansas, 2034 Becker Drive, West Campus, Lawrence, KS 66047, USA.
| | - Qin Yin
- Department of Medicinal Chemistry, Delbert M. Shankel Structural Biology Center, University of Kansas, 2034 Becker Drive, West Campus, Lawrence, KS 66047, USA.
| | - Jeffrey Aubé
- Department of Medicinal Chemistry, Delbert M. Shankel Structural Biology Center, University of Kansas, 2034 Becker Drive, West Campus, Lawrence, KS 66047, USA.
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25
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Posada IM, Busto JV, Goñi FM, Alonso A. Membrane binding and insertion of the predicted transmembrane domain of human scramblase 1. Biochim Biophys Acta 2014; 1838:388-97. [PMID: 24099740 DOI: 10.1016/j.bbamem.2013.09.018] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2013] [Revised: 09/19/2013] [Accepted: 09/25/2013] [Indexed: 10/26/2022]
Abstract
Human phospholipid scramblase 1 (SCR) was originally described as an intrinsic membrane protein catalyzing transbilayer phospholipid transfer in the absence of ATP. More recently, a role as a nuclear transcription factor has been proposed for SCR, either in addition or alternatively to its capacity to facilitate phospholipid flip-flop. Uncertainties exist as well from the structural point of view. A predicted α-helix (aa residues 288-306) located near the C-terminus has been alternatively proposed as a transmembrane domain, or as a protein core structural element. This paper explores the possibilities of the above helical segment as a transmembrane domain. To this aim two peptides were synthesized, one corresponding to the 19 α-helical residues, and one containing both the helix and the subsequent 12-residues constituting the C-end of the protein. The interaction of these peptides with lipid monolayers and bilayers was tested with Langmuir balance surface pressure measurements, proteoliposome reconstitution and analysis, differential scanning calorimetry, tests of bilayer permeability, and fluorescence confocal microscopy. Bilayers of 28 different lipid compositions were examined in which lipid electric charge, bilayer fluidity and lateral heterogeneity (domain formation) were varied. All the results concur in supporting the idea that the 288-306 peptide of SCR becomes membrane inserted in the presence of lipid bilayers. Thus, the data are in agreement with the possibility of SCR as an integral membrane protein, without rejecting alternative cell locations.
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Key Words
- 1,1,1,3,3,3-hexafluoro-2-propanol
- 1,1′-dioctadecyl-3,3,3′,3′-tetramethyl-indodicarbocyanine
- 8-aminonaphtalene-1,3,6-trisulfonic acid sodium salt
- ANTS
- DID
- DPX
- GUVs
- HFIP
- LUVs
- Lipid phases
- MLVs
- PC
- PE
- PG
- PI
- PLSCR1
- PS
- SCR
- SCR 288–306 peptide
- SCR 288–318 peptide
- Scramblase
- TM
- TM19
- TM31C
- Transbilayer
- Transmembrane helix
- giant unilamellar vesicles
- human phospholipid scramblase 1, or hPLSCR1
- large unilamellar vesicles
- multilamellar vesicles
- p-xylene-bis(pyridinium) bromide
- pSM
- palmitoyl sphingomyelin
- phosphatidylcholine
- phosphatidylethanolamine
- phosphatidylglycerol
- phosphatidylinositol
- phosphatidylserine
- transmembrane
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Dai X, Chang P, Zhu Q, Liu W, Sun Y, Zhu S, Jiang Z. Chitosan oligosaccharides protect rat primary hippocampal neurons from oligomeric β-amyloid 1-42-induced neurotoxicity. Neurosci Lett 2013; 554:64-9. [PMID: 23999027 DOI: 10.1016/j.neulet.2013.08.046] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2013] [Revised: 08/20/2013] [Accepted: 08/22/2013] [Indexed: 10/26/2022]
Abstract
β-Amyloid peptide (Aβ), the major component of senile plaques in patients with Alzheimer's disease (AD), is believed to facilitate the progressive neurodegeneration that occurs in this disease. Mounting natural compounds are proved to be potential candidates for the prevention and treatment of AD. Chitosan oligosaccharides (COSs), the enzymatic hydrolysates of chitosan, have been reported to possess diverse biological activities. Here we investigated the effect of COSs on oligomeric Aβ-mediated toxicity in rat primary hippocampal neurons. Pretreatment with COSs markedly inhibited cell death induced by Aβ exposure as determined by cell viability assay and lactate dehydrogenase release assay. In parallel, the generation of reactive oxygen species and lipid peroxidation were attenuated by COSs. Furthermore, our results indicated that COSs remarkably prevented Aβ-induced cell apoptosis as manifested by depressing the elevation of Bax/Bcl-2 ratio and caspase-3 activation, suggesting that the neuroprotective effect of COSs could be partially due to apoptosis regulation. In addition, pretreatment with COSs significantly blocked Aβ-induced phosphorylation of c-Jun N-terminal kinase. Taken together, these findings may shed light on the role of COSs as a potential therapeutic agent for AD.
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Affiliation(s)
- Xueling Dai
- Beijing Key Laboratory of Bioactive Substances and Functional Foods, Beijing Union University, Beijing 100191, China; Department of Physiology and Pathophysiology, Peking University School of Basic Medical Sciences, Beijing 100191, China; Research Institute for Science and Technology of Functional Food, Beijing Union University, Beijing 100191, China
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Michalek M, Salnikov E, Bechinger B. Structure and topology of the huntingtin 1-17 membrane anchor by a combined solution and solid-state NMR approach. Biophys J 2013; 105:699-710. [PMID: 23931318 PMCID: PMC3736738 DOI: 10.1016/j.bpj.2013.06.030] [Citation(s) in RCA: 88] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2013] [Revised: 06/07/2013] [Accepted: 06/17/2013] [Indexed: 10/26/2022] Open
Abstract
The very amino-terminal domain of the huntingtin protein is directly located upstream of the protein's polyglutamine tract, plays a decisive role in several important properties of this large protein and in the development of Huntington's disease. This huntingtin 1-17 domain is on the one hand known to markedly increase polyglutamine aggregation rates and on the other hand has been shown to be involved in cellular membrane interactions. Here, we determined the high-resolution structure of huntingtin 1-17 in dodecyl phosphocholine micelles and the topology of its helical domain in oriented phosphatidylcholine bilayers. Using two-dimensional solution NMR spectroscopy the low-energy conformations of the polypeptide were identified in the presence of dodecyl phosphocholine detergent micelles. In a next step a set of four solid-state NMR angular restraints was obtained from huntingtin 1-17 labeled with (15)N and (2)H at selected sites. Of the micellar ensemble of helical conformations only a limited set agrees in quantitative detail with the solid-state angular restraints of huntingtin 1-17 obtained in supported planar lipid bilayers. Thereby, the solid-state NMR data were used to further refine the domain structure in phospholipid bilayers. At the same time its membrane topology was determined and different motional regimes of this membrane-associated domain were explored. The pronounced structural transitions of huntingtin 1-17 upon membrane-association result in a α-helical conformation from K6 to F17, i.e., up to the very start of the polyglutamine tract. This amphipathic helix is aligned nearly parallel to the membrane surface (tilt angle ∼77°) and is characterized by a hydrophobic ridge on one side and an alternation of cationic and anionic residues that run along the hydrophilic face of the helix. This arrangement facilitates electrostatic interactions between huntingtin 1-17 domains and possibly with the proximal polyglutamine tract.
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Affiliation(s)
| | | | - Burkhard Bechinger
- Université de Strasbourg/CNRS, UMR7177, Institut de Chimie, Strasbourg, France
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Xu Y, Liu Y, Zhu J, Wang E. Discovered triethylamine as impurity in synthetic DNAs for and by electrochemiluminescence techniques. Talanta 2013; 116:308-14. [PMID: 24148408 DOI: 10.1016/j.talanta.2013.03.089] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2012] [Revised: 07/04/2012] [Accepted: 03/14/2013] [Indexed: 11/23/2022]
Abstract
The purity of the synthetic oligonucleotides is very important because it is crucial for the accuracy of the established biological assays. Herein, it was discovered that one impurity in synthetic DNAs might affect the experiment results of electrochemiluminescence (ECL) detection techniques, which was never reported before. According to a series of experiments using ECL detection methods combined with capillary electrophoresis (CE) (CE-ECL), the impurity was identified as triethylamine (TEA), which came from incomplete removal after HPLC purification of synthetic DNAs. Moreover, CE-ECL technique was for the first time to be proposed for discovering, identifying and sensitive determining the possible impurity such as TEA in various DNA samples, which was usually neglected by other detection techniques for purification quality control of synthetic oligonucleotides. A detection range from 5.00×10(-10) to 2.00×10(-5) M with a detection limit as low as 50 nM (S/N=3) was reached for TEA. Through further designed ECL methods and data analysis, situations which would be really affected by the impurity of TEA were studied. To avoid or eliminate the impact of the TEA impurity on ECL applications, judgment basis for choosing purification ways was discussed according to individual requirements.
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Caillon L, Lequin O, Khemtémourian L. Evaluation of membrane models and their composition for islet amyloid polypeptide-membrane aggregation. Biochim Biophys Acta 2013; 1828:2091-8. [PMID: 23707907 DOI: 10.1016/j.bbamem.2013.05.014] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2012] [Revised: 04/26/2013] [Accepted: 05/13/2013] [Indexed: 01/01/2023]
Abstract
Human islet amyloid polypeptide (IAPP) forms amyloid fibrils in the pancreatic islets of patients suffering from type 2 diabetes mellitus (T2DM). The formation of IAPP fibrils has been shown to cause membrane damage which most likely is responsible for the death of pancreatic islet β-cells during the pathogenesis of T2DM. Several studies have demonstrated a clear interaction between IAPP and lipid membranes. However the effect of different lipid compositions and of various membrane mimetics (including micelles, bicelles, SUV and LUV) on fibril formation kinetics and fibril morphology has not yet systematically been analysed. Here we report that the interaction of IAPP with various membrane models promoted different processes of fibril formation. Our data reveal that in SDS and DPC micelles, IAPP adopts a stable α-helical structure for several days, suggesting that the micelle models may stabilize monomeric or small oligomeric species of IAPP. In contrast, zwitterionic DMPC/DHPC bicelles and DOPC SUV accelerate the fibril formation compared to zwitterionic DOPC LUV, indicating that the size of the membrane model and its curvature influence the fibrillation process. Negatively charged membranes decrease the lag-time of the fibril formation kinetics while phosphatidylethanolamine and cholesterol have an opposite effect, probably due to the modulation of the physical properties of the membrane and/or due to direct interactions with IAPP within the membrane core. Finally, our results show that the modulation of lipid composition influences not only the growth of fibrils at the membrane surface but also the interactions of β-sheet oligomers with membranes.
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Key Words
- 1,1,1,3,3,3-hexafluoro-2-propanol
- 1,2-dihexanoyl-sn-glycero-3-phosphocholine
- 1,2-dimyristoyl-sn-glycero-3-phosphocholine
- 1,2-dioleoyl-sn-glycero-3-phospho-(1′-rac-glycerol)
- 1,2-dioleoyl-sn-glycero-3-phospho-L-serine
- 1,2-dioleoyl-sn-glycero-3-phosphocholine
- 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine
- 1,2-dipalmitoyl-sn-glycero-3-phosphocholine
- 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine
- Aggregation kinetics
- Amyloid
- CD
- Chol
- DHPC
- DMPC
- DMSO
- DOPC
- DOPE
- DOPG
- DOPS
- DPC
- DPPC
- Fibril morphology
- HFIP
- IAPP
- LUV
- Model membranes (LUV SUV, bicelles, micelles)
- POPC
- Phospholipid
- SDS
- SM
- ThT
- Thioflavin T
- cholesterol
- circular dichroism
- dimethyl sulfoxide
- dodecyl phosphocholine
- human Islet Amyloid Polypeptide
- large unilamellar vesicle
- sodium dodecyl sulphate
- sphingomyelin
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Affiliation(s)
- Lucie Caillon
- UPMC Univ Paris 06, UMR 7203 CNRS-UPMC-ENS, Laboratoire des Biomolécules, 4 place Jussieu, 75005 Paris, France
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