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Syryamina VN, Sannikova NE, De Zotti M, Gobbo M, Formaggio F, Dzuba SA. Tylopeptin B peptide antibiotic in lipid membranes at low concentrations: Self-assembling, mutual repulsion and localization. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2021; 1863:183585. [PMID: 33640429 DOI: 10.1016/j.bbamem.2021.183585] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 11/25/2020] [Revised: 01/27/2021] [Accepted: 02/08/2021] [Indexed: 02/08/2023]
Abstract
The medium-length peptide Tylopeptin B possesses activity against Gram-positive bacteria. It binds to bacterial membranes altering their mechanical properties and increasing their permeability. This action is commonly related with peptide self-assembling, resulting in the formation of membrane channels. Here, pulsed double electron-electron resonance (DEER) data for spin-labeled Tylopeptin B in palmitoyl-oleoyl-glycero-phosphocholine (POPC) model membrane reveal that peptide self-assembling starts at concentration as low as 0.1 mol%; above 0.2 mol% it attains a saturation-like dependence with a mean number of peptides in the cluster <n> = 3.3. Using the electron spin echo envelope modulation (ESEEM) technique, Tylopeptin B molecules are found to possess a planar orientation in the membrane. In the peptide concentration range between 0.1 and 0.2 mol%, DEER data show that the peptide clusters have tendency of mutual repulsion, with a circle of inaccessibility of radius around 20 nm. It may be proposed that within this radius the peptides destabilize the membrane, providing so the peptide antimicrobial activity. Exploiting spin-labeled stearic acids as a model for free fatty acids (FFA), we found that at concentrations of 0.1-0.2 mol% the peptide promotes formation of lipid-mediated FFA clusters; further increase in peptide concentration results in dissipation of these clusters.
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Affiliation(s)
- Victoria N Syryamina
- Institute of Chemical Kinetics and Combustion, RAS, Novosibirsk 630090, Russian Federation.
| | | | - Marta De Zotti
- Department of Chemical Sciences, University of Padova, 35131 Padova, Italy; Institute of Biomolecular Chemistry, Padova Unit, CNR, 35131 Padova, Italy
| | - Marina Gobbo
- Department of Chemical Sciences, University of Padova, 35131 Padova, Italy; Institute of Biomolecular Chemistry, Padova Unit, CNR, 35131 Padova, Italy
| | - Fernando Formaggio
- Department of Chemical Sciences, University of Padova, 35131 Padova, Italy; Institute of Biomolecular Chemistry, Padova Unit, CNR, 35131 Padova, Italy
| | - Sergei A Dzuba
- Institute of Chemical Kinetics and Combustion, RAS, Novosibirsk 630090, Russian Federation.
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2
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Das S, Ben Haj Salah K, Djibo M, Inguimbert N. Peptaibols as a model for the insertions of chemical modifications. Arch Biochem Biophys 2018; 658:16-30. [DOI: 10.1016/j.abb.2018.09.016] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2018] [Revised: 09/05/2018] [Accepted: 09/18/2018] [Indexed: 12/13/2022]
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3
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Biondi B, Peggion C, De Zotti M, Pignaffo C, Dalzini A, Bortolus M, Oancea S, Hilma G, Bortolotti A, Stella L, Pedersen JZ, Syryamina VN, Tsvetkov YD, Dzuba SA, Toniolo C, Formaggio F. Conformational properties, membrane interaction, and antibacterial activity of the peptaibiotic chalciporin A: Multitechnique spectroscopic and biophysical investigations on the natural compound and labeled analogs. Biopolymers 2017; 110. [PMID: 29127716 DOI: 10.1002/bip.23083] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2017] [Revised: 10/06/2017] [Accepted: 10/15/2017] [Indexed: 02/28/2024]
Abstract
In this work, an extensive set of spectroscopic and biophysical techniques (including FT-IR absorption, CD, 2D-NMR, fluorescence, and CW/PELDOR EPR) was used to study the conformational preferences, membrane interaction, and bioactivity properties of the naturally occurring synthetic 14-mer peptaibiotic chalciporin A, characterized by a relatively low (≈20%), uncommon proportion of the strongly helicogenic Aib residue. In addition to the unlabeled peptide, we gained in-depth information from the study of two labeled analogs, characterized by one or two residues of the helicogenic, nitroxyl radical-containing TOAC. All three compounds were prepared using the SPPS methodology, which was carefully modified in the course of the syntheses of TOAC-labeled analogs in view of the poorly reactive α-amino function of this very bulky residue and the specific requirements of its free-radical side chain. Despite its potentially high flexibility, our results point to a predominant, partly amphiphilic, α-helical conformation for this peptaibiotic. Therefore, not surprisingly, we found an effective membrane affinity and a remarkable penetration propensity. However, chalciporin A exhibits a selectivity in its antibacterial activity not in agreement with that typical of the other members of this peptide class.
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Affiliation(s)
- Barbara Biondi
- Institute of Biomolecular, Chemistry, Padova Unit, CNR, Padova, 35131, Italy
| | - Cristina Peggion
- Department of Chemical Sciences, University of Padova, Padova, 35131, Italy
| | - Marta De Zotti
- Department of Chemical Sciences, University of Padova, Padova, 35131, Italy
| | - Chiara Pignaffo
- Department of Chemical Sciences, University of Padova, Padova, 35131, Italy
| | - Annalisa Dalzini
- Department of Chemical Sciences, University of Padova, Padova, 35131, Italy
| | - Marco Bortolus
- Department of Chemical Sciences, University of Padova, Padova, 35131, Italy
| | - Simona Oancea
- Department of Agricultural Sciences and Food Engineering, "Lucian Blaga" University of Sibiu, Sibiu, 550012, Romania
| | - Geta Hilma
- Department of Medicine, "Lucian Blaga" University of Sibiu, Sibiu, 550012, Romania
| | - Annalisa Bortolotti
- Department of Chemical Sciences and Technologies, University of Rome Tor Vergata, Rome, 00133, Italy
| | - Lorenzo Stella
- Department of Chemical Sciences and Technologies, University of Rome Tor Vergata, Rome, 00133, Italy
| | - Jens Z Pedersen
- Department of Biology, University of Rome Tor Vergata, Rome, 00133, Italy
| | - Victoria N Syryamina
- Institute of Chemical Kinetics and Combustion, Novosibirsk, 630090, Russian Federation
| | - Yuri D Tsvetkov
- Institute of Chemical Kinetics and Combustion, Novosibirsk, 630090, Russian Federation
| | - Sergei A Dzuba
- Institute of Chemical Kinetics and Combustion, Novosibirsk, 630090, Russian Federation
| | - Claudio Toniolo
- Institute of Biomolecular, Chemistry, Padova Unit, CNR, Padova, 35131, Italy
- Department of Chemical Sciences, University of Padova, Padova, 35131, Italy
| | - Fernando Formaggio
- Institute of Biomolecular, Chemistry, Padova Unit, CNR, Padova, 35131, Italy
- Department of Chemical Sciences, University of Padova, Padova, 35131, Italy
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4
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Abstract
Mushrooms are known to produce over 140 natural products bearing an indole heterocycle. In this review, the isolation of these mushroom-derived indole alkaloids is discussed, along with their associated biological activities.
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Affiliation(s)
- Joshua A Homer
- School of Chemical Sciences, University of Auckland , 23 Symonds Street, Auckland 1142, New Zealand
| | - Jonathan Sperry
- School of Chemical Sciences, University of Auckland , 23 Symonds Street, Auckland 1142, New Zealand
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5
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Otto A, Laub A, Wendt L, Porzel A, Schmidt J, Palfner G, Becerra J, Krüger D, Stadler M, Wessjohann L, Westermann B, Arnold N. Chilenopeptins A and B, Peptaibols from the Chilean Sepedonium aff. chalcipori KSH 883. JOURNAL OF NATURAL PRODUCTS 2016; 79:929-38. [PMID: 26953507 DOI: 10.1021/acs.jnatprod.5b01018] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
The Chilean Sepedonium aff. chalcipori strain KSH 883, isolated from the endemic Boletus loyo Philippi, was studied in a polythetic approach based on chemical, molecular, and biological data. A taxonomic study of the strain using molecular data of the ITS, EF1-α, and RPB2 barcoding genes confirmed the position of the isolated strain within the S. chalcipori clade, but also suggested the separation of this clade into three different species. Two new linear 15-residue peptaibols, named chilenopeptins A (1) and B (2), together with the known peptaibols tylopeptins A (3) and B (4) were isolated from the semisolid culture of strain KSH 883. The structures of 1 and 2 were elucidated on the basis of HRESIMS(n) experiments in conjunction with comprehensive 1D and 2D NMR analysis. Thus, the sequence of chilenopeptin A (1) was identified as Ac-Aib(1)-Ser(2)-Trp(3)-Aib(4)-Pro(5)-Leu(6)-Aib(7)-Aib(8)-Gln(9)-Aib(10)-Aib(11)-Gln(12)-Aib(13)-Leu(14)-Pheol(15), while chilenopeptin B (2) differs from 1 by the replacement of Trp(3) by Phe(3). Additionally, the total synthesis of 1 and 2 was accomplished by a solid-phase approach, confirming the absolute configuration of all chiral amino acids as l. Both the chilenopeptins (1 and 2) and tylopeptins (3 and 4) were evaluated for their potential to inhibit the growth of phytopathogenic organisms.
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Affiliation(s)
- Alexander Otto
- Department of Bioorganic Chemistry, Leibniz Institute of Plant Biochemistry , Weinberg 3, D-06120 Halle (Saale), Germany
| | - Annegret Laub
- Department of Bioorganic Chemistry, Leibniz Institute of Plant Biochemistry , Weinberg 3, D-06120 Halle (Saale), Germany
| | - Lucile Wendt
- Department of Microbial Drugs, Helmholtz Centre for Infection Research , Inhoffenstrasse 7, D-38124 Braunschweig, Germany
| | - Andrea Porzel
- Department of Bioorganic Chemistry, Leibniz Institute of Plant Biochemistry , Weinberg 3, D-06120 Halle (Saale), Germany
| | - Jürgen Schmidt
- Department of Bioorganic Chemistry, Leibniz Institute of Plant Biochemistry , Weinberg 3, D-06120 Halle (Saale), Germany
| | - Götz Palfner
- Departamento de Botanica, Facultad de Ciencias Naturales y Oceanograficas, Universidad de Concepción , Casilla 160-C, Concepción, Chile
| | - José Becerra
- Departamento de Botanica, Facultad de Ciencias Naturales y Oceanograficas, Universidad de Concepción , Casilla 160-C, Concepción, Chile
| | - Dirk Krüger
- Department of Soil Ecology, Helmholtz Centre for Environmental Research , Theodor-Lieser-Strasse 4, D-06120 Halle (Saale), Germany
| | - Marc Stadler
- Department of Microbial Drugs, Helmholtz Centre for Infection Research , Inhoffenstrasse 7, D-38124 Braunschweig, Germany
| | - Ludger Wessjohann
- Department of Bioorganic Chemistry, Leibniz Institute of Plant Biochemistry , Weinberg 3, D-06120 Halle (Saale), Germany
- Institute of Chemistry, Faculty of Natural Sciences II, Martin Luther University Halle-Wittenberg , Kurt-Mothes-Strasse 2, D-06120 Halle (Saale), Germany
| | - Bernhard Westermann
- Department of Bioorganic Chemistry, Leibniz Institute of Plant Biochemistry , Weinberg 3, D-06120 Halle (Saale), Germany
- Institute of Chemistry, Faculty of Natural Sciences II, Martin Luther University Halle-Wittenberg , Kurt-Mothes-Strasse 2, D-06120 Halle (Saale), Germany
| | - Norbert Arnold
- Department of Bioorganic Chemistry, Leibniz Institute of Plant Biochemistry , Weinberg 3, D-06120 Halle (Saale), Germany
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De Zotti M, Ballano G, Jost M, Salnikov ES, Bechinger B, Oancea S, Crisma M, Toniolo C, Formaggio F. Solution synthesis, conformational analysis, and antimicrobial activity of three alamethicin F50/5 analogs bearing a trifluoroacetyl label. Chem Biodivers 2015; 11:1163-91. [PMID: 25146762 DOI: 10.1002/cbdv.201300394] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2013] [Indexed: 11/07/2022]
Abstract
We prepared, by solution-phase methods, and fully characterized three analogs of the membrane-active peptaibiotic alamethicin F50/5, bearing a single trifluoroacetyl (Tfa) label at the N-terminus, at position 9 (central region) or at position 19 (C-terminus), and with the three Gln at positions 7, 18, and 19 replaced by Glu(OMe) residues. To add the Tfa label at position 9 or 19, a γ-trifluoroacetylated α,γ-diaminobutyric acid (Dab) residue was incorporated as a replacement for the original Val(9) or Glu(OMe)(19) amino acid. We performed a detailed conformational analysis of the three analogs (using FT-IR absorption, CD, 2D-NMR, and X-ray diffraction), which clearly showed that Tfa labeling does not introduce any dramatic backbone modification in the predominantly α-helical structure of the parent peptaibiotic. The results of an initial solid-state (19)F-NMR study on one of the analogs favor the conclusion that the Tfa group is a very promising reporter for the analysis of peptaibioticmembrane interactions. Finally, we found that the antimicrobial activities of the three newly synthesized analogs depend on the position of the Tfa label in the peptide sequence.
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Affiliation(s)
- Marta De Zotti
- ICB, Padova Unit, CNR, Department of Chemistry, University of Padova, I-35131 Padova.
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7
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Jia YY, Li XY, Wang PA, Wen AD. Facile access to unnatural dipeptide-alcohols based on cis-2,5-disubstituted pyrrolidines. Molecules 2015; 20:2922-30. [PMID: 25679051 PMCID: PMC6272547 DOI: 10.3390/molecules20022922] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2014] [Accepted: 01/30/2015] [Indexed: 11/17/2022] Open
Abstract
Well-defined unnatural dipeptide-alcohols based on a cis-2,5-disubstitued pyrrolidine backbone were synthesized from commercially available starting materials meso-diethyl-2,5-dibromoadipate, (S)-(−)-1-phenylethylamine, and phenylalaninol. The structures of these unnatural dipeptide-alcohols are supported by HRMS, 1H- and 13C-NMR spectroscopy. These unnatural dipeptide-alcohols can act as building blocks for peptidomimetics.
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Affiliation(s)
- Yan-Yan Jia
- Department of Pharmacy, Xijing Hospital, Fourth Military Medical University, Changle West Road 15, Xi'an 710032, China.
| | - Xiao-Ye Li
- Department of Medicinal Chemistry, School of Pharmacy, Fourth Military Medical University, Changle West Road 169, Xi'an 710032, China.
| | - Ping-An Wang
- Department of Medicinal Chemistry, School of Pharmacy, Fourth Military Medical University, Changle West Road 169, Xi'an 710032, China.
| | - Ai-Dong Wen
- Department of Pharmacy, Xijing Hospital, Fourth Military Medical University, Changle West Road 15, Xi'an 710032, China.
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8
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Milov AD, Tsvetkov YD, Bortolus M, Maniero AL, Gobbo M, Toniolo C, Formaggio F. Synthesis and conformational properties of a TOAC doubly spin-labeled analog of the medium-length, membrane active peptaibiotic ampullosporin a as revealed by cd, fluorescence, and EPR spectroscopies. Biopolymers 2014; 102:40-8. [DOI: 10.1002/bip.22362] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2013] [Revised: 07/10/2013] [Accepted: 07/12/2013] [Indexed: 11/10/2022]
Affiliation(s)
- Alexander D. Milov
- Institute of Chemical Kinetics and Combustion; Novosibirsk 630090 Russian Federation
| | - Yuri D. Tsvetkov
- Institute of Chemical Kinetics and Combustion; Novosibirsk 630090 Russian Federation
| | - Marco Bortolus
- Department of Chemical Sciences; University of Padova; 35131 Padova Italy
| | - Anna Lisa Maniero
- Department of Chemical Sciences; University of Padova; 35131 Padova Italy
| | - Marina Gobbo
- Department of Chemical Sciences; University of Padova; 35131 Padova Italy
- Institute of Biomolecular Chemistry; Padova Unit, CNR 35131 Padova Italy
| | - Claudio Toniolo
- Department of Chemical Sciences; University of Padova; 35131 Padova Italy
- Institute of Biomolecular Chemistry; Padova Unit, CNR 35131 Padova Italy
| | - Fernando Formaggio
- Department of Chemical Sciences; University of Padova; 35131 Padova Italy
- Institute of Biomolecular Chemistry; Padova Unit, CNR 35131 Padova Italy
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9
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Gatto E, Bocchinfuso G, Palleschi A, Oncea S, De Zotti M, Formaggio F, Toniolo C, Venanzi M. 3D structure, dynamics, and activity of synthetic analog of the peptaibiotic trichodecenin I. Chem Biodivers 2013; 10:887-903. [PMID: 23681732 DOI: 10.1002/cbdv.201200388] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2012] [Indexed: 11/07/2022]
Abstract
In this contribution, we report on the conformational preferences of synthetic analogs of the antimicrobial peptide trichodecenin I in solution. This 6-amino acid residue long peptide is characterized by a single, strongly helicogenic Aib residue in the central part of the sequence and is rich in the conformationally mobile Gly residues. It has been reported that, in CHCl3 solution and in the crystal state, this peptaibiotic adopts a non-helical, multiple β-turn conformation, whereas a 310 /α-helical structure was obtained from an X-ray diffraction study on a trichodecenin I analog (TDT4W6) containing the fluorescent Trp residue in position 6 (replacing Ile) and an equally helicogenic TOAC residue in position 4 (replacing Aib). In this work, we applied spectroscopic techniques and molecular-dynamics calculations, in particular, on the fluorescent TDT4W6 trichodecenin I analog with the aim at investigating its 3D-structural and dynamical features in solution. Our results revealed that TDT4W6 can be described by an ensemble of conformers quickly interconverting in the nanosecond time scale. The most populated cluster has a conformation similar to the NMR structure of native trichodecenin I in CHCl3 . However, also helical-like conformers are present, even if poorly populated and less stable under the analytical conditions.
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Affiliation(s)
- Emanuela Gatto
- Department of Chemical Sciences and Technologies, University of Rome 'Tor Vergata', I-00133 Rome.
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10
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Milov AD, Tsvetkov YD, De Zotti M, Prinzivalli C, Biondi B, Formaggio F, Toniolo C, Gobbo M. Aggregation modes of the spin mono-labeled tylopeptin B and heptaibin peptaibiotics in frozen solutions of weak polarity as studied by PELDOR spectroscopy. J STRUCT CHEM+ 2013. [DOI: 10.1134/s0022476613070056] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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Pradeille N, Tzouros M, Möhle K, Linden A, Heimgartner H. Total synthesis of the peptaibols hypomurocin A3 and hypomurocin A5, and their conformation analysis. Chem Biodivers 2013; 9:2528-58. [PMID: 23161633 DOI: 10.1002/cbdv.201200285] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2012] [Indexed: 11/06/2022]
Abstract
The total syntheses of hypomurocin A3 and hypomuricin A5 (HM A3 and HM A5, resp.) in solution phase are described. These syntheses have been successfully achieved by applying the 'azirine/oxazolone method' to introduce the two Aib-Pro units into the backbone of these undecapeptaibols in one step with methyl 2,2-dimethyl-2H-azirine-3-prolinate as the 'Aib-Pro synthon'. The coupling of Z-protected (Z=(benzyloxy)carbonyl) amino acids or peptide acids with amino acid tert-butyl esters and of peptide segments was carried out according to the TBTU (=O-(benzotriazol-1-yl)-N,N,N',N'-tetramethyluronium tetrafluoroborate) and HOBt (=1-hydroxybenzotriazole) protocol. Purification by reversed-phase HPLC gave the peptides in pure form. The products were characterized by optical rotation, NMR and IR spectroscopy, mass spectrometry, and elemental analysis. The crystal structures of HM A3 and of an octapeptide fragment of HM A5 could be obtained. An NMR analysis was also carried out with HM A3 and HM A5 to determine their conformations in solution. A global structural comparison between the three sequences of HM A1, HM A3, and HM A5 was performed, as well as the HPLC correlation of the natural HM A family and the synthetic samples.
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Affiliation(s)
- Nicolas Pradeille
- Organisch-chemisches Institut der Universität Zürich, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland
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12
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Gobbo M, Merli E, Biondi B, Oancea S, Toffoletti A, Formaggio F, Toniolo C. Synthesis and preliminary conformational analysis of TOAC spin-labeled analogues of the medium-length peptaibiotic tylopeptin B. J Pept Sci 2011; 18:37-44. [DOI: 10.1002/psc.1413] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2011] [Revised: 07/18/2011] [Accepted: 08/02/2011] [Indexed: 11/09/2022]
Affiliation(s)
- Marina Gobbo
- ICB-Padova Unit, CNR, Department of Chemical Sciences; University of Padova; 35131 Padova Italy
| | - Elisabetta Merli
- ICB-Padova Unit, CNR, Department of Chemical Sciences; University of Padova; 35131 Padova Italy
| | - Barbara Biondi
- ICB-Padova Unit, CNR, Department of Chemical Sciences; University of Padova; 35131 Padova Italy
| | - Simona Oancea
- Department of Biochemistry and Toxicology; University “Lucian Blaga” Sibiu; Sibiu 550012 Romania
| | - Antonio Toffoletti
- ICB-Padova Unit, CNR, Department of Chemical Sciences; University of Padova; 35131 Padova Italy
| | - Fernando Formaggio
- ICB-Padova Unit, CNR, Department of Chemical Sciences; University of Padova; 35131 Padova Italy
| | - Claudio Toniolo
- ICB-Padova Unit, CNR, Department of Chemical Sciences; University of Padova; 35131 Padova Italy
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De Zotti M, Biondi B, Crisma M, Hjørringgaard CU, Berg A, Brückner H, Toniolo C. Isovaline in naturally occurring peptides: A nondestructive methodology for configurational assignment. Biopolymers 2011; 98:36-49. [DOI: 10.1002/bip.21679] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2011] [Revised: 05/03/2011] [Accepted: 05/10/2011] [Indexed: 11/08/2022]
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De Zotti M, Biondi B, Peggion C, Park Y, Hahm KS, Formaggio F, Toniolo C. Synthesis, preferred conformation, protease stability, and membrane activity of heptaibin, a medium-length peptaibiotic. J Pept Sci 2011; 17:585-94. [PMID: 21495119 DOI: 10.1002/psc.1364] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2011] [Accepted: 01/18/2011] [Indexed: 11/11/2022]
Abstract
The medium-length peptaibiotics are characterized by a primary structure of 14-16 amino acid residues. Despite the interesting antibiotic and antifungal properties exhibited by these membrane-active peptides, their exact mechanism of action is still unknown. Here, we present our results on heptaibin, a 14-amino acid peptaibiotic found to exhibit antimicrobial activity against Staphylococcus aureus. We carried out the very challenging synthesis of heptaibin on solid phase and a detailed conformational analysis in solution. The peptaibiotic is folded in a mixed 3₁₀-/α-helix conformation which exhibits a remarkable amphiphilic character. We also find that it is highly stable toward degradation by proteolytic enzymes and nonhemolytic. Finally, fluorescence leakage experiments using small unilamellar vesicles of three different compositions revealed that heptaibin, although uncharged, is a selective compound for permeabilization of model membranes mimicking the overall negatively charged surface of Gram-positive bacteria. This latter finding is in agreement with the originally published antimicrobial activity data.
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Affiliation(s)
- Marta De Zotti
- ICB, Padova Unit, CNR, Department of Chemistry, University of Padova, via Marzolo 1, 35131 Padova, Italy.
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