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Fuller RO, Taylor MR, Duggin M, Bissember AC, Canty AJ, Judd MM, Cox N, Moggach SA, Turner GF. Enhanced synthesis of oxo-verdazyl radicals bearing sterically-and electronically-diverse C3-substituents. Org Biomol Chem 2021; 19:10120-10138. [PMID: 34757372 DOI: 10.1039/d1ob01946e] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The synthetic viability of the hydrazine- and phosgene-free synthesis of 1,5-dimethyl oxo-verdazyl radicals has been improved via a detailed study investigating the influence of the aryl substituent on tetrazinanone ring formation. Although it is well established that functionalisation at the C3 position of the tetrazinanone ring does not influence the nature of the radical, it is crucial in applications development. The synthetic route involves a 4-step sequence: Schiff base condensation of a carbohydrazide with an arylaldehyde, alkylation, ring closure then subsequent oxidation to the radical. We found that the presence of strong electron-donating substituents and electron rich heterocycles, result in a significant reduction in yield during both the alkylation and ring closure steps. This can, in part, be alleviated by milder alkylation conditions and further substitution of the aryl group. In comparison, more facile formation of the tetrazine ring was observed with examples containing electron-withdrawing groups and with meta- or para-substitution. Density functional theory suggests that the ring closure proceeds via the formation of an ion pair. Electron paramagnetic resonance spectroscopy provides insight into the precise electronic structure of the radical with small variations in hyperfine coupling constants revealing subtle differences.
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Affiliation(s)
- Rebecca O Fuller
- School of Natural Sciences - Chemistry, University of Tasmania, Hobart, Tasmania, Australia.
| | - Madeleine R Taylor
- School of Natural Sciences - Chemistry, University of Tasmania, Hobart, Tasmania, Australia.
| | - Margot Duggin
- School of Natural Sciences - Chemistry, University of Tasmania, Hobart, Tasmania, Australia.
| | - Alex C Bissember
- School of Natural Sciences - Chemistry, University of Tasmania, Hobart, Tasmania, Australia.
| | - Allan J Canty
- School of Natural Sciences - Chemistry, University of Tasmania, Hobart, Tasmania, Australia.
| | - Martyna M Judd
- Research School of Chemistry, The Australia National University, Australian Capital Territory, Australia
| | - Nicholas Cox
- Research School of Chemistry, The Australia National University, Australian Capital Territory, Australia
| | - Stephen A Moggach
- School of Molecular Sciences - Chemistry, The University of Western Australia, Crawley, Western Australia, Australia
| | - Gemma F Turner
- School of Molecular Sciences - Chemistry, The University of Western Australia, Crawley, Western Australia, Australia
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Lee TH, Hofferek V, Sani MA, Separovic F, Reid GE, Aguilar MI. The impact of antibacterial peptides on bacterial lipid membranes depends on stage of growth. Faraday Discuss 2021; 232:399-418. [DOI: 10.1039/d0fd00052c] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Impact of maculatin 1.1 on supported lipid bilayers (SLBs) derived from early growth phase (EGP) or stationary growth phase (SGP) E. coli lipid extracts, monitored by atomic force microscopy which images bilayer morphology in real time.
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Affiliation(s)
- Tzong-Hsien Lee
- Department of Biochemistry and Molecular Biology, Monash University, Clayton, VIC 3800, Australia
| | - Vinzenz Hofferek
- School of Chemistry, Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, VIC 3010, Australia
| | - Marc-Antoine Sani
- School of Chemistry, Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, VIC 3010, Australia
| | - Frances Separovic
- School of Chemistry, Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, VIC 3010, Australia
| | - Gavin E. Reid
- School of Chemistry, Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, VIC 3010, Australia
- Department of Biochemistry and Molecular Biology, University of Melbourne, Parkville, VIC 3010, Australia
| | - Marie-Isabel Aguilar
- Department of Biochemistry and Molecular Biology, Monash University, Clayton, VIC 3800, Australia
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Hammond K, Ryadnov MG, Hoogenboom BW. Atomic force microscopy to elucidate how peptides disrupt membranes. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2020; 1863:183447. [PMID: 32835656 DOI: 10.1016/j.bbamem.2020.183447] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 06/10/2020] [Revised: 07/30/2020] [Accepted: 08/13/2020] [Indexed: 12/24/2022]
Abstract
Atomic force microscopy is an increasingly attractive tool to study how peptides disrupt membranes. Often performed on reconstituted lipid bilayers, it provides access to time and length scales that allow dynamic investigations with nanometre resolution. Over the last decade, AFM studies have enabled visualisation of membrane disruption mechanisms by antimicrobial or host defence peptides, including peptides that target malignant cells and biofilms. Moreover, the emergence of high-speed modalities of the technique broadens the scope of investigations to antimicrobial kinetics as well as the imaging of peptide action on live cells in real time. This review describes how methodological advances in AFM facilitate new insights into membrane disruption mechanisms.
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Affiliation(s)
- Katharine Hammond
- National Physical Laboratory, Hampton Road, Teddington TW11 0LW, UK; London Centre for Nanotechnology, University College London, London WC1H 0AH, UK; Department of Physics & Astronomy, University College London, London WC1E 6BT, UK.
| | - Maxim G Ryadnov
- National Physical Laboratory, Hampton Road, Teddington TW11 0LW, UK; Department of Physics, King's College London, Strand Lane, London WC2R 2LS, UK.
| | - Bart W Hoogenboom
- London Centre for Nanotechnology, University College London, London WC1H 0AH, UK; Department of Physics & Astronomy, University College London, London WC1E 6BT, UK.
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