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Banaś K, Lenartowicz P, Staś M, Dziuk B, Siodłak D. Insight into the Structure of Victorin, the Host-Selective Toxin from the Oat Pathogen Cochliobolus victoriae. Studies of the Unique Dehydroamino Acid β-Chlorodehydroalanine. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2023. [PMID: 37486973 PMCID: PMC10401702 DOI: 10.1021/acs.jafc.3c01387] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/26/2023]
Abstract
Victorins, a family of peptide toxins, produced by the fungal pathogen Cochliobolus victoriae and responsible for disease of some oat varieties, contain a β-chlorodehydroalanine residue, ΔAla(βCl). To determine the conformational properties of this unique dehydroamino acid, a series of model compounds was studied using X-ray, NMR, and FT-IR methods, supported by theoretical calculations. The ΔAla(βCl) geometrical isomers differ in conformational profile. The isomer Z prefers the helical conformation α (φ, ψ = -61°, -24°), PPII type conformation β (φ, ψ = -47°, 136°), and semiextended conformation β2 (φ, ψ = -116°, 9°) in weakly and more polar solutions. The isomer E prefers mainly the extended conformation C5 (φ, ψ = -177°, 160°), but with an increase of the environment polarity also conformations β (φ, ψ = -44°, 132°) and α (φ, ψ = -53°, -39°). In the most stable conformations the N-H···Cl hydrogen bond (5γ) occurs, created between the chlorine atom of the side chain and the N-H donor of the flanking amide group. The method of synthesis of the β-chlorodehydroalanine residue is proposed, by chlorination of dehydroalanine and then the photoisomerization from the isomer Z to E. The presented results indicate that the assignment of the geometrical isomer of the ΔAla(βCl) residue in naturally occurring victorins still remains an open question, despite being crucial for biological activity.
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Affiliation(s)
- Karolina Banaś
- Faculty of Chemistry, University of Opole, Oleska 48, 45-052 Opole, Poland
| | - Paweł Lenartowicz
- Faculty of Chemistry, University of Opole, Oleska 48, 45-052 Opole, Poland
| | - Monika Staś
- Faculty of Chemistry, University of Opole, Oleska 48, 45-052 Opole, Poland
| | - Błażej Dziuk
- Faculty of Chemistry, Wroclaw University of Science and Technology, Wybrzeze Wyspianskiego 27, 50-370 Wroclaw, Poland
- Faculty of Chemistry, University of Wroclaw, Joliot-Curie 14, Wroclaw 50-383, Poland
| | - Dawid Siodłak
- Faculty of Chemistry, University of Opole, Oleska 48, 45-052 Opole, Poland
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Staś M, Broda MA, Siodłak D. Thiazole-amino acids: influence of thiazole ring on conformational properties of amino acid residues. Amino Acids 2021; 53:673-686. [PMID: 33837859 PMCID: PMC8128816 DOI: 10.1007/s00726-021-02974-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2020] [Accepted: 03/29/2021] [Indexed: 12/29/2022]
Abstract
Post-translational modified thiazole-amino acid (Xaa-Tzl) residues have been found in macrocyclic peptides (e.g., thiopeptides and cyanobactins), which mostly inhibit protein synthesis in Gram + bacteria. Conformational study of the series of model compounds containing this structural motif with alanine, dehydroalanine, dehydrobutyrine and dehydrophenylalanine were performed using DFT method in various environments. The solid-state crystal structure conformations of thiazole-amino acid residues retrieved from the Cambridge Structural Database were also analysed. The studied structural units tend to adopt the unique semi-extended β2 conformation; which is stabilised mainly by N-H⋯NTzl hydrogen bond, and for dehydroamino acids also by π-electron conjugation. The conformational preferences of amino acids with a thiazole ring were compared with oxazole analogues and the role of the sulfur atom in stabilising the conformations of studied peptides was discussed.
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Affiliation(s)
- Monika Staś
- Faculty of Chemistry, University of Opole, 45-052, Opole, Poland.
- Institute of Organic Chemistry and Biochemistry of the Czech Academy of Science, Flemingovo Náměstí 2, 166 10, Praha 6, Czech Republic.
| | | | - Dawid Siodłak
- Faculty of Chemistry, University of Opole, 45-052, Opole, Poland.
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Impact of the ΔPhe configuration on the Boc-Gly-ΔPhe-NHMe conformation: experiment and theory. Struct Chem 2019. [DOI: 10.1007/s11224-019-01387-w] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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Staś M, Bujak M, Broda MA, Siodłak D. Conformational preferences and synthesis of isomers Z and E of oxazole-dehydrophenylalanine. Biopolymers 2017; 106:283-94. [PMID: 27061820 DOI: 10.1002/bip.22852] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2016] [Revised: 03/30/2016] [Accepted: 04/05/2016] [Indexed: 12/17/2022]
Abstract
Dehydrophenylalanine, ΔPhe, is the most commonly studied α,β-dehydroamino acid. In nature, further modifications of the α,β-dehydroamino acids were found, for example, replacement of the C-terminal amide group by oxazole ring. The conformational properties of oxazole-dehydrophenylalanine residue (ΔPhe-Ozl), both isomers Z and E, were investigated. To determine all possible conformations, theoretical calculations were performed using Ac-(Z/E)-ΔPhe-Ozl(4-Me) model compounds at M06-2X/6-31++G(d,p) level of theory. Ac-(Z/E)-ΔPhe-Ozl-4-COOEt compounds were synthesized and the conformational preferences of each isomer, Z and E, were investigated using FTIR and NMR-NOE in solutions of increasing polarity (CHCl3 , DMSO-d6). The solid-state low-temperature structures of Ac-(Z)-ΔPhe-Ozl-4-COOEt and its intermediate analog Ac-(Z)-ΔPhe-Ozn(4-OH)-4-COOEt were also determined. In a weakly polar environment, the ΔPhe-Ozl residue has a tendency to adopt the conformation β2 with the calculated φ and ψ angles of -127° and 0° for the isomer Z and -170° and 26° for the isomer E. The increase of environment polarity favors the helical conformation α and the beta-turn like conformation β, but the conformation β2 seems to be still accessible. The (E)-ΔPhe-Ozl residue can be obtained from the isomer Z in photoisomerization reaction. However, hydroxyl-oxazoline-dehydrophenylalanine ΔPhe-Ozn(4-OH) decomposes in such conditions. Alternatively, (E)-ΔPhe-NH2 can be applied as a substrate in the Hantzsch reaction. © 2016 Wiley Periodicals, Inc. Biopolymers (Pept Sci) 106: 283-294, 2016.
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Affiliation(s)
- Monika Staś
- Faculty of Chemistry, University of Opole, Oleska 48, Opole, 45-052, Poland
| | - Maciej Bujak
- Faculty of Chemistry, University of Opole, Oleska 48, Opole, 45-052, Poland
| | - Małgorzata A Broda
- Faculty of Chemistry, University of Opole, Oleska 48, Opole, 45-052, Poland
| | - Dawid Siodłak
- Faculty of Chemistry, University of Opole, Oleska 48, Opole, 45-052, Poland
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Peggion C, Moretto A, Formaggio F, Crisma M, Toniolo C. Multiple, consecutive, fully-extended 2.0₅-helix peptide conformation. Biopolymers 2016; 100:621-36. [PMID: 23893391 DOI: 10.1002/bip.22267] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2013] [Revised: 04/16/2013] [Accepted: 04/19/2013] [Indexed: 02/01/2023]
Abstract
The peptide 2.0(5)-helix does exist. It has been experimentally authenticated both in the crystalline state (by X-ray diffraction) and in solution (by several spectroscopic techniques). It is the most common conformation for C(α)-tetrasubstituted α-amino acids with at least two atoms in each side chain, provided that cyclization on the C(α)-atom is absent. X-Ray diffraction has allowed a detailed description of its geometrical and three-dimensional (3D)-structural features. The infrared absorption and the nuclear magnetic resonance parameters characteristics of this multiple, consecutive, fully-extended structure have been described. Conformational energy calculations are in agreement with the experimental findings. As the contribution per amino acid residue to the length of this helix is the longest possible, its exploitation as a molecular spacer is quite promising. However, it is a rather fragile 3D-structure and particularly sensitive to solvent polarity. Interestingly, in such a case, it may reversibly convert to the much shorter 3(10)-helix, thus generating an attractive molecular spring.
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Affiliation(s)
- Cristina Peggion
- Institute of Biomolecular Chemistry, CNR, Padova Unit, Department of Chemistry, University of Padova, 35131, Padova, Italy
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Buczek A, Makowski M, Jewgiński M, Latajka R, Kupka T, Broda MA. Toward engineering efficient peptidomimetics. Screening conformational landscape of two modified dehydroaminoacids. Biopolymers 2016; 101:28-40. [PMID: 23606332 DOI: 10.1002/bip.22264] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2013] [Accepted: 04/12/2013] [Indexed: 11/11/2022]
Abstract
Effective peptidomimetics should posses structural rigidity and appropriate interaction pattern leading to potential spatial and electronic matching to the target receptor site. Rational design of such small bioactive molecules could push chemical synthesis and molecular modeling toward faster progress in medicinal chemistry. Conformational properties of N-t-butoxycarbonyl-glycine-(E/Z)-dehydrophenylalanine N',N'-dimethylamides (Boc-Gly-(E/Z)-ΔPhe-NMe2 ) in chloroform were studied by NMR and IR spectroscopy. The experimental findings were supported by extensive calculations at DFT(B3LYP, M06-2X) and MP2 levels of theory and the β-turn tendency for both isomers of the studied dipeptide were determined in vacuum and in solution. The theoretical data and experimental IR results were used as an additional information for the NMR-based determination of the detailed solution conformations of the peptides. The obtained results reveal that N-methylation of C-terminal amide group changes dramatically the conformational properties of studied dehydropeptides. Theoretical conformational analysis reveals that the tendency to adopt β-turn conformations is much weaker for the N-methylated Z isomer (Boc-Gly-(Z)-ΔPhe-NMe2 ), both in vacuum and in polar environment. On the contrary, N-methylated E isomer (Boc-Gly-(E)-ΔPhe-NMe2 ) can easily adopt β-turn conformation, but the backbone torsion angles (φ1, ψ1, φ2, ψ2) are off the limits for common β-turn types.
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Affiliation(s)
- Aneta Buczek
- Department of Physical Chemistry and Molecular Modeling, Faculty of Chemistry, University of Opole, Oleska 48, 45-052, Opole, Poland
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Wałęsa R, Man D, Engel G, Siodłak D, Kupka T, Ptak T, Broda MA. The Impact of Model Peptides on Structural and Dynamic Properties of Egg Yolk Lecithin Liposomes - Experimental and DFT Studies. Chem Biodivers 2015; 12:1007-24. [DOI: 10.1002/cbdv.201400179] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2014] [Indexed: 12/21/2022]
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Siodłak D, Macedowska-Capiga A, Broda MA, Kozioł AE, Lis T. The cis-trans isomerization of N-methyl-α,β-dehydroamino acids. Biopolymers 2014. [PMID: 23203691 DOI: 10.1002/bip.22082] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Dehydroamino acids with the methylated N-terminal peptide group occur in natural small cyclic peptides. The structural analysis was used to investigate the cis-trans isomerization of the N-terminal tertiary amide group of diamides: Ac-(Z)-Δ(Me)Abu-NHMe (1), Ac-(Z)-Δ(Me)Phe-NHMe (2), Ac-(E)-Δ(Me)Phe-NHMe (3), Ac-Δ(Me)Ala-NHMe (4), and Ac-(Me)Ala-NHMe (5). The compounds were analyzed in the solid state by an X-ray crystallography (1-3), and in the solution by FTIR (MeCN and CHCl(3) ) and NMR (DMSO-d6 and CDCl(3) ) methods (1-5). In the solid state, the studied compounds adopt the cis configuration of N-terminal amide. In solution, this configuration also prevails for the dehydroamino acids 1-4, in contrast to the saturated analog 5. The results indicate that N-methyldehydroamino acids present a promising tool to induce the cis configuration of the amide bond.
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Affiliation(s)
- Dawid Siodłak
- Faculty of Chemistry, University of Opole, Oleska 48, Opole 45-052, Poland.
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Buczek A, Wałęsa R, Broda MA. β-turn tendency in N-methylated peptides with dehydrophenylalanine residue: DFT study. Biopolymers 2012; 97:518-28. [DOI: 10.1002/bip.22034] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2010] [Revised: 02/02/2011] [Accepted: 02/04/2011] [Indexed: 01/10/2023]
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Buczek AM, Ptak T, Kupka T, Broda MA. Experimental and theoretical NMR and IR studies of the side-chain orientation effects on the backbone conformation of dehydrophenylalanine residue. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2011; 49:343-349. [PMID: 21506144 DOI: 10.1002/mrc.2753] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/28/2011] [Revised: 02/09/2011] [Accepted: 02/16/2011] [Indexed: 05/30/2023]
Abstract
Conformation of N-acetyl-(E)-dehydrophenylalanine N', N'-dimethylamide (Ac-(E)-ΔPhe-NMe(2)) in solution, a member of (E)-α, β-dehydroamino acids, was studied by NMR and infrared spectroscopy and the results were compared with those obtained for (Z) isomer. To support the spectroscopic interpretation, the Φ, Ψ potential energy surfaces were calculated at the MP2/6-31 + G(d,p) level of theory in chloroform solution modeled by the self-consistent reaction field-polarizable continuum model method. All minima were fully optimized by the MP2 method and their relative stabilities were analyzed in terms of π-conjugation, internal H-bonds and dipole interactions between carbonyl groups. The obtained NMR spectral features were compared with theoretical nuclear magnetic shieldings, calculated using Gauge Independent Atomic Orbitals (GIAO) approach and rescaled to theoretical chemical shifts using benzene as reference. The calculated indirect nuclear spin-spin coupling constants were compared with available experimental parameters.
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Affiliation(s)
- Aneta M Buczek
- Faculty of Chemistry, University of Opole, 48, Oleska Street, 45-052 Opole, Poland
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Buczek A, Siodłak D, Bujak M, Broda MA. Effects of side-chain orientation on the backbone conformation of the dehydrophenylalanine residue. Theoretical and X-ray study. J Phys Chem B 2011; 115:4295-306. [PMID: 21443240 DOI: 10.1021/jp200949t] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Two E isomers of α,β-dehydro-phenylalanine, Ac-(E)-ΔPhe-NHMe (1a) and Ac-(E)-ΔPhe-NMe(2) (2a), have been synthesized and their low temperature structures determined by single-crystal X-ray diffraction. A systematic theoretical analysis was performed on these molecules and their Z isomers (1b and 2b). The ϕ,ψ potential energy surfaces were calculated at the MP2/6-31+G(d,p) and B3LYP/6-31+G(d,p) levels in the gas phase and at the B3LYP/6-31+G(d,p) level in the chloroform and water solutions with the SCRF-PCM method. All minima were fully optimized by the MP2 and DFT methods, and their relative stabilities were analyzed in terms of π-conjugation, internal H-bonds, and dipole-dipole interactions between carbonyl groups. The results indicate that all the studied compounds can adopt the conformation H (ϕ, ψ ≈ ±40°, ∓120°) which is atypical for standard amino acids residues. A different arrangement of the side chain in the E and Z isomers causes them to have different conformational preferences. In the presence of a polar solvent both Z isomers of ΔPhe (1b and 2b) are found to adopt the 3(10)-helical conformation (left- and right-handed are equally likely). On the other hand, this conformation is not accessible or highly energetic for E isomers of ΔPhe (1a and 2a). Those isomers have an intrinsic inclination to have an extended conformation. The conformational space of the Z isomers is much more restricted than that of the E derivative both in the gas phase and in solution. In the gas phase the E isomers of ΔPhe have lower energies than the Z ones, but in the aqueous solution the energy order is reversed.
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Affiliation(s)
- Aneta Buczek
- Faculty of Chemistry, University of Opole, Poland
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Broda MA, Buczek A, Siodłak D, Rzeszotarska B. The effect of beta-methylation on the conformation of alpha, beta-dehydrophenylalanine: a DFT study. J Pept Sci 2009; 15:465-73. [PMID: 19408247 DOI: 10.1002/psc.1137] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Dehydroamino acids are non-coded amino acids that offer unique conformational properties. Dehydrophenylalanine (DeltaPhe) is most commonly used to modify bioactive peptides to constrain the topography of the phenyl ring in the side chain, which commonly serves as a pharmacophore. The Ramachandran maps (in the gas phase and in CHCl(3) mimicking environments) of DeltaPhe analogues with methyl groups at the beta position of the side chain as well as at the C-terminal amide were calculated using the B3LYP/6-31 + G** method. Unexpectedly, beta-methylation alone results in an increase of conformational freedom of the affected DeltaPhe residue. However, further modification by introducing an additional methyl group at C-terminal methyl amide results in a steric crowding that fixes the torsion angle psi of all conformers to the value 123 degrees , regardless of the Z or E position of the phenyl ring. The number of conformers is reduced and the accessible conformational space of the residues is very limited. In particular, (Z)-Delta(betaMe)Phe with the tertiary C-terminal amide can be classified as the amino acid derivative that has a single conformational state as it seems to adopt only the beta conformation.
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Inai Y, Ousaka N, Miwa Y. Theoretical Comparison between Three-Point and Two-Point Binding Modes for Chiral Discrimination upon the N-Terminal Sequence of 310-Helix. Polym J 2006. [DOI: 10.1295/polymj.38.432] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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