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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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Liu D, Bardaud JX, Imani Z, Robin S, Gloaguen E, Brenner V, Aitken DJ, Mons M. Length-Dependent Transition from Extended to Folded Shapes in Short Oligomers of an Azetidine-Based α-Amino Acid: The Critical Role of NH···N H-Bonds. Molecules 2023; 28:5048. [PMID: 37446709 DOI: 10.3390/molecules28135048] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2023] [Revised: 06/15/2023] [Accepted: 06/23/2023] [Indexed: 07/15/2023] Open
Abstract
Hydrogen bonds (H-bonds) are ubiquitous in peptides and proteins and are central to the stabilization of their structures. Inter-residue H-bonds between non-adjacent backbone amide NH and C=O motifs lead to the well-known secondary structures of helices, turns and sheets, but it is recognized that other H-bonding modes may be significant, including the weak intra-residue H-bond (called a C5 H-bond) that implicates the NH and C=O motifs of the same amino acid residue. Peptide model compounds that adopt stable C5 H-bonds are not readily available and the so-called 2.05-helix, formed by successive C5 H-bonds, is an elusive secondary structure. Using a combination of theoretical chemistry and spectroscopic studies in both the gas phase and solution phase, we have demonstrated that derivatives of 3-amino-1-methylazetidine-3-carboxylic acid, Aatc(Me) can form sidechain-backbone N-H···N C6γ H-bonds that accompany-and thereby stabilize-C5 H-bonds. In the capped trimer of Aatc(Me), extended C5/C6γ motifs are sufficiently robust to challenge classical 310-helix formation in solution and the fully-extended 2.05-helix conformer has been characterized in the gas phase. Concurrent H-bonding support for successive C5 motifs is a new axiom for stabilizing the extended backbone secondary structure in short peptides.
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Affiliation(s)
- Dayi Liu
- Université Paris-Saclay, CNRS, ICMMO, 91400 Orsay, France
| | | | - Zeynab Imani
- Université Paris-Saclay, CNRS, ICMMO, 91400 Orsay, France
| | - Sylvie Robin
- Université Paris-Saclay, CNRS, ICMMO, 91400 Orsay, France
- Université Paris Cité, Faculté de Pharmacie, 75006 Paris, France
| | - Eric Gloaguen
- Université Paris-Saclay, CEA, CNRS, LIDYL, 91191 Gif-sur-Yvette, France
| | - Valérie Brenner
- Université Paris-Saclay, CEA, CNRS, LIDYL, 91191 Gif-sur-Yvette, France
| | - David J Aitken
- Université Paris-Saclay, CNRS, ICMMO, 91400 Orsay, France
| | - Michel Mons
- Université Paris-Saclay, CEA, CNRS, LIDYL, 91191 Gif-sur-Yvette, France
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3
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Mundlapati VR, Imani Z, D'mello VC, Brenner V, Gloaguen E, Baltaze JP, Robin S, Mons M, Aitken DJ. N-H⋯X interactions stabilize intra-residue C5 hydrogen bonded conformations in heterocyclic α-amino acid derivatives. Chem Sci 2021; 12:14826-14832. [PMID: 34820098 PMCID: PMC8597926 DOI: 10.1039/d1sc05014a] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2021] [Accepted: 10/21/2021] [Indexed: 12/23/2022] Open
Abstract
Nature makes extensive and elaborate use of hydrogen bonding to assemble and stabilize biomolecular structures. The shapes of peptides and proteins rely significantly on N–H⋯O
Created by potrace 1.16, written by Peter Selinger 2001-2019
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C interactions, which are the linchpins of turns, sheets and helices. The C5 H-bond, in which a single residue provides both donor and acceptor, is generally considered too weak to force the backbone to adopt extended structures. Exploiting the synergy between gas phase (experimental and quantum chemistry) and solution spectroscopies to decipher IR spectroscopic data, this work demonstrates that the extended C5-based conformation in 4-membered ring heterocyclic α-amino acid derivatives is significantly stabilized by the formation of an N–H⋯X H-bond. In this synergic system the strength of the C5 interaction remains constant while the N–H⋯X H-bond strength, and thereby the support provided by it, varies with the heteroatom. In 4-membered ring heterocyclic α-amino acid derivatives, extended conformations based on intraresidue C5 H-bonds can be stabilized by N–H⋯X H-bonds, making the combined C5–C6γ structures prominent in both gas phase and in weakly polar solutions.![]()
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Affiliation(s)
| | - Zeynab Imani
- Université Paris-Saclay, CNRS, ICMMO 91405 Orsay France
| | - Viola C D'mello
- Université Paris-Saclay, CEA, CNRS, LIDYL 91191 Gif-sur-Yvette France
| | - Valérie Brenner
- Université Paris-Saclay, CEA, CNRS, LIDYL 91191 Gif-sur-Yvette France
| | - Eric Gloaguen
- Université Paris-Saclay, CEA, CNRS, LIDYL 91191 Gif-sur-Yvette France
| | | | - Sylvie Robin
- Université Paris-Saclay, CNRS, ICMMO 91405 Orsay France .,Université de Paris, Faculté de Pharmacie 75006 Paris France
| | - Michel Mons
- Université Paris-Saclay, CEA, CNRS, LIDYL 91191 Gif-sur-Yvette France
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Nicke L, Horx P, Müller R, Els-Heindl S, Geyer A. Tryptophan Analogues with Fixed Side-Chain Orientation: Expanding the Scope. Chembiochem 2020; 22:330-335. [PMID: 33463878 PMCID: PMC7891422 DOI: 10.1002/cbic.202000424] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2020] [Revised: 08/12/2020] [Indexed: 12/13/2022]
Abstract
A generalized synthetic strategy is proposed here for the synthesis of asymmetric β‐indoylated amino acids by 8‐aminoquinoline (8AQ)‐directed C(sp3)‐H functionalization of suitably protected precursors. Peptides containing one of the four stereoisomers of (indol‐3‐yl)‐3‐phenylalanine at position 2 of the parent peptide KwFwLL‐NH2 (w=d‐Trp) cover a wide range of activities as ghrelin receptor inverse agonists, among them the most active described until now. This application exemplarily shows how β‐indoylated amino acids can be used for the systematic variation of the position of an indole group in a bioactive peptide.
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Affiliation(s)
- Lennart Nicke
- Faculty of Chemistry, Philipps-University Marburg, Hans-Meerwein-Strasse 4, 35032, Marburg, Germany
| | - Philip Horx
- Faculty of Chemistry, Philipps-University Marburg, Hans-Meerwein-Strasse 4, 35032, Marburg, Germany
| | - Ronny Müller
- Faculty of Life Sciences, Institute of Biochemistry, Leipzig University, Brüderstrasse 34, 04103, Leipzig, Germany
| | - Sylvia Els-Heindl
- Faculty of Life Sciences, Institute of Biochemistry, Leipzig University, Brüderstrasse 34, 04103, Leipzig, Germany
| | - Armin Geyer
- Faculty of Chemistry, Philipps-University Marburg, Hans-Meerwein-Strasse 4, 35032, Marburg, Germany
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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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Wałęsa R, Ptak T, Siodłak D, Kupka T, Broda MA. Experimental and theoretical NMR studies of interaction between phenylalanine derivative and egg yolk lecithin. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2014; 52:298-305. [PMID: 24639342 DOI: 10.1002/mrc.4064] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/19/2013] [Revised: 01/18/2014] [Accepted: 02/28/2014] [Indexed: 06/03/2023]
Abstract
The interaction of phenylalanine diamide (Ac-Phe-NHMe) with egg yolk lecithin (EYL) in chloroform was studied by (1)H and (13)C NMR. Six complexes EYL-Ac-Phe-NHMe, stabilized by N-H···O or/and C-H···O hydrogen bonds, were optimized at M06-2X/6-31G(d,p) level. The assignment of EYL and Ac-Phe-NHMe NMR signals was supported using GIAO (gauge including atomic orbital) NMR calculations at VSXC and B3LYP level of theory combined with STO-3Gmag basis set. Results of our study indicate that the interaction of peptides with lecithin occurs mainly in the polar 'head' of the lecithin. Additionally, the most probable lecithin site of H-bond interaction with Ac-Phe-NHMe is the negatively charged oxygen in phosphate group that acts as proton acceptor.
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Affiliation(s)
- Roksana Wałęsa
- Faculty of Chemistry, University of Opole, Oleska 48 Str., 45-052, Opole, Poland
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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, Broda MA. DFT study of N–H···O hydrogen bond between model dehydropeptides and water molecule. Mol Phys 2013. [DOI: 10.1080/00268976.2013.847979] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
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Malek K, Makowski M, Królikowska A, Bukowska J. Comparative studies on IR, Raman, and surface enhanced Raman scattering spectroscopy of dipeptides containing ΔAla and ΔPhe. J Phys Chem B 2012; 116:1414-25. [PMID: 22208201 DOI: 10.1021/jp208586j] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Three dipeptides containing dehydroresidues (ΔAla, Δ((Z))Phe, and Δ((E))Phe) were examined by IR, Raman, and surface-enhanced Raman techniques for the first time. The effect of the size and isomer type of the β-substituent in the dehydroresidue on the conformational structure of the peptide was evaluated by using the analysis of IR and Raman bands. Additionally, SERS spectroscopy provided insight into the adsorption mechanism of these species on the metal surface. SERS spectra were recorded at alkaline pH on the silver sol using visible light excitation. The dehydroresidues studied here strongly influenced the SERS profile of the peptides. The most pronounced SERS signal for all dipeptides was assigned to the symmetric stretching vibration of the carboxylate ions. This indicates that the dehydropeptides studied here primarily adsorb via the deprotonated carboxylic group. Additionally, the enhanced SERS bands in the range 1550-1650 cm(-1) show differences in contribution of the dehydroresidue to the adsorption mechanism of the studied peptides.
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Affiliation(s)
- Kamilla Malek
- Faculty of Chemistry, Jagiellonian Chemistry, Ingardena 3, 30-060 Krakow, Poland.
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Siodłak D, Grondys J, Broda MA. The conformational properties of α,β-dehydroamino acids with a C-terminal ester group. J Pept Sci 2011; 17:690-9. [PMID: 21805538 DOI: 10.1002/psc.1390] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2011] [Revised: 05/31/2011] [Accepted: 06/03/2011] [Indexed: 11/06/2022]
Abstract
α,β-Dehydroamino acid esters occur in nature. To investigate their conformational properties, a systematic theoretical analysis was performed on the model molecules Ac-ΔXaa-OMe [ΔXaa = ΔAla, (E)-ΔAbu, (Z)-ΔAbu, ΔVal] at the B3LYP/6-311+ + G(d,p) level in the gas phase as well as in chloroform and water solutions with the self-consistent reaction field-polarisable continuum model method. The Fourier transform IR spectra in CCl(4) and CHCl(3) have been analysed as well as the analogous solid state conformations drawn from The Cambridge Structural Database. The ΔAla residue has a considerable tendency to adopt planar conformations C5 (ϕ, ψ ≈ - 180°, 180°) and β2 (ϕ, ψ ≈ - 180°, 0°), regardless of the environment. The ΔVal residue prefers the conformation β2 (ϕ, ψ ≈ - 120°, 0°) in a low polar environment, but the conformations α (ϕ, ψ ≈ - 55°, 35°) and β (ϕ, ψ ≈ - 55°, 145°) when the polarity increases. The ΔAbu residues reveal intermediate properties, but their conformational dispositions depend on configuration of the side chain of residue: (E)-ΔAbu is similar to ΔAla, whereas (Z)-ΔAbu to ΔVal. Results indicate that the low-energy conformation β2 is the characteristic feature of dehydroamino acid esters. The studied molecules constitute conformational patterns for dehydroamino acid esters with various side chain substituents in either or both Z and E positions.
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Affiliation(s)
- Dawid Siodłak
- Faculty of Chemistry, Opole University, Oleska 48, 45-052 Opole, Poland.
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Siodłak D, Grondys J, Lis T, Bujak M, Broda MA, Rzeszotarska B. The conformational properties of dehydrobutyrine and dehydrovaline: theoretical and solid-state conformational studies. J Pept Sci 2010; 16:496-505. [PMID: 20645424 DOI: 10.1002/psc.1267] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Dehydrobutyrine is the most naturally occurring dehydroamino acid. It is also the simplest dehydroamino acid having the geometrical isomers E/Z. To investigate its conformational properties, a theoretical analysis was performed on N-acetyl-alpha,beta-dehydrobutyrine N'-methylamides, Ac-(E)-DeltaAbu-NHMe and Ac-(Z)-DeltaAbu-NHMe, as well as the dehydrovaline derivative Ac-DeltaVal-NHMe. The phi, psi potential energy surfaces and the localised conformers were calculated at the B3LYP/6-311 + + G(d,p) level of theory both in vacuo and with inclusion of the solvent (chloroform, water) effect (SCRF method). The X-ray crystal structures of Ac-(Z)-DeltaAbu-NHMe and Ac-DeltaVal-NHMe were determined at 85 and 100 K, respectively. The solid-state conformational preferences for the studied residues have been analysed and compared with the other related structures. Despite the limitations imposed by the C(alpha) = C(beta) double bond on the topography of the side chains, the main chains of the studied dehydroamino acids are more flexible than in standard alanine. The studied dehydroamino acids differ in their conformational preferences, which depend on the polarity of the environment. This might be a reason why the nature quite precisely differentiates between DeltaVal and each of the DeltaAbu isomers, and why, particularly so with the latter, they are used as a conformational tool to influence the biological action of usually small, cyclic dehydropeptides.
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Affiliation(s)
- Dawid Siodłak
- Faculty of Chemistry, University of Opole, Oleska 48, 45-052 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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Broda MA, Ciszak EM, Koziol AE, Pietrzynski G, Rzeszotarska B. Conformational investigation of α,β-dehydropeptides. XVI. β-turn tendency in Ac-Pro-ΔXaa-NHMe: crystallographic and theoretical studies. J Pept Sci 2006; 12:538-49. [PMID: 16733828 DOI: 10.1002/psc.763] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
The crystal structures of two diastereomeric alpha,beta-dehydrobutyrine peptides Ac-Pro-(Z)-DeltaAbu-NHMe (I) and Ac-Pro-(E)-DeltaAbu-NHMe (II) have been determined. Both dehydropeptides adopt betaI-turn conformation characterized by the pairs of (phi(i+1), psi(i+1)) and (phi(i+2), psi(i+2)) angles as -66, -19, -97, 11 degrees for I and -59, -27, -119, 29 degrees for II. In each peptide, the betaI turn is stabilized by (i + 3) --> i intramolecular hydrogen bonds with N...O distance of 3.12 A for I and 2.93 A for II. These structures have been compared to the crystal structures of homologous peptides Ac-Pro-DeltaVal-NHMe and Ac-Pro-DeltaAla-NHMe. Theoretical analyses by DFT/B3LYP/6-31 + G** method of conformers formed by these four peptides and by the saturated peptide Ac-Pro-Ala-NHMe revealed that peptides with a (Z) substituent at the C(beta) (i+2) atom of dehydroamino acid, i.e. Ac-Pro-DeltaVal-NHMe and Ac-Pro-(Z)-DeltaAbu-NHMe, predominantly form beta turns, both in vacuo and in polar environment. The tendency to adopt beta-turn conformation is much weaker for the peptides lacking the (Z) substituent, Ac-Pro-(E)-DeltaAbu-NHMe and Ac-Pro-DeltaAla-NHMe. The latter adopts a semi-extended or an extended conformation in every polar environment, including a weakly polar solvent. The saturated peptide Ac-Pro-Ala-NHMe in vacuo prefers a beta-turn conformation, but in polar environment the differences between various conformers are small. The role of pi-electron correlation and intramolecular hydrogen bonds interaction in stabilizing the hairpin structures are discussed.
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Affiliation(s)
- Malgorzata A Broda
- Institute of Chemistry, University of Opole, Olesja Street 48, 45-052 Opole, Poland.
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Broda MA, Siodłak D, Rzeszotarska B. Conformational investigation of alpha,beta-dehydropeptides. XV: N-acetyl-alpha,beta-dehydroamino acid N 'N '-dimethylamides: conformational properties from infrared and theoretical studies. J Pept Sci 2005; 11:546-55. [PMID: 15782429 DOI: 10.1002/psc.655] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The FTIR spectra were analysed in the region of the nu(s)(N-H), AI(C=O) and nu(s)(Calpha=Cbeta) bands for a series of Ac-DeltaXaa-NMe2, where DeltaXaa = DeltaAla, (Z)-DeltaAbu, (Z)-DeltaLeu, (Z)-DeltaPhe and DeltaVal, to determine a predominant solution conformation of these alpha,beta-dehydropeptide-related molecules. Measurements were taken in CCl4, DCM and MeCN solutions. In the same way, spectra of saturated analogues Ac-Xaa-NMe2, where Xaa = Ala, Abu, Leu, Phe and Val, were investigated. To help interpret the spectroscopic results, conformational maps were calculated by the B3LYP/6-31+G** method. Also, the relative energies of all conformers of the dehydro compounds in vacuo as well as in the studied solvents in addition to the theoretical IR frequencies of these conformers were calculated. For comparison, molecules of two saturated analogues, Ac-L-Ala-NMe2 and Ac-L-Phe-NMe2, were calculated in a similar way. Both unsaturated and saturated compounds, which have an aliphatic side chain, occur in CCl4 and DCM mainly as a mixture of extended conformers with the C5 H-bond and open conformers. As solvent polarity increases, participation of the open conformers also increases, and in MeCN, the model amides are almost exclusively in the open form, except Ac-DeltaAla-NMe2, which shows a small amount of the H-bonded conformer. Ac-DeltaAla-NMe2 and Ac-DeltaAbu-NMe2 have stronger C5 hydrogen bonds than those of their saturated counterparts. As the calculations indicate, the open conformation of the unsaturated amides is conformer H/F with phi, psi -44 +/- 5 degrees, 127 +/- 4 degrees. This is the second lowest in energy conformer in vacuo and in CCl4 and the lowest one in more polar solvents. The open conformation of Ac-L-Ala-NMe2 constitutes conformer C with phi, psi -101.5 degrees, 112.7 degrees. For Ac-DeltaAla-NMe2 and Ac-DeltaAbu-NMe2, FTIR also reveals the presence of a third conformer. Calculations indicate that is the semiextended conformer D with the N1-H1...N2 hydrogen bond/contact. In all solvents, Ac-L-Phe-NMe2 and Ac-(Z)-DeltaPhe-NMe2 show only the extended E and the open H/F, respectively. In both there is an amide/pi(Ph) interaction.
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Broda MA, Siodłak D, Rzeszotarska B. Conformational investigation of alpha,beta-dehydropeptides. N-acetyl-(E)-dehydrophenylalanine N'-methylamide: conformational properties from infrared and theoretical studies, part XIV. J Pept Sci 2005; 11:235-44. [PMID: 15635637 DOI: 10.1002/psc.601] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
N-Acetyl-(E)-dehydrophenylalanine N'-methylamide [Ac-(E)-DeltaPhe-NHMe], one of a few representative (E)-alpha,beta-dehydroamino acids, was studied by FTIR in dichloromethane and acetonitrile. To support spectroscopic interpretations and to gain some deeper insight into the Ac-(E)-DeltaPhe-NHMe molecule, the Ramachandran potential energy surface was calculated by the B3LYP/6-31G*//HF/3-21G method and the conformers localized were fully optimized at the B3LYP/6-31 + G** level. The spectra and calculations were compared with those of the related molecules Ac-DeltaAla-NHMe and Ac-(Z)-DeltaPhe-NHMe. The title compound assumes two conformational states in equilibrium in dichloromethane solution with a predominance of the extended conformer E. The Ac-(E)-DeltaPhe-NHMe spectrum is like that of Ac-DeltaAla-NHMe, particularly in the region of bands AI and AII, and unlike that of Ac-(Z)-DeltaPhe-NHMe. The positions of bands AI and II together with the nu(s)(N1--H1) band proves that the conformers E of both DeltaAla and (E)-DeltaPhe compounds are stabilized by the quite strong C5 hydrogen bonds N1--H1...O2. The same conclusion is drawn from the Ramachandran diagrams. The conformers E of both compounds are placed in the global minima and the gaps in energy order between them and the second conformer are large. The conformers E of DeltaAla and (E)-DeltaPhe, apart from the N1--H1...O2 hydrogen bond, show the Cbeta--H...O1 interaction, and Ac-(E)-DeltaPhe-NHMe displays the NH/pi interaction with the N2--H2 projecting in the first carbon atom of the phenyl ring. The C5 hydrogen bond is stronger in (E)-DeltaPhe than that in the DeltaAla compound. This is in agreement with interactions found in the calculated structures and can be explained by the influence of the phenyl ring in position (E). In acetonitrile, the molecule of Ac-(E)-DeltaPhe-NHMe loses its C5 hydrogen bond and becomes unfolded, whereas that of Ac-DeltaAla-NHMe does not vary practically. Adopting conformation E in a non-polar solvent seems to be a general feature of the (E)-DeltaXaa residues.
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Broda MA, Rospenk M, Siodłak D, Rzeszotarska B. Association of model peptides and dehydropeptides: N-acetyl-l-alanine- and dehydroalanine N′,N′-dimethylamides. J Mol Struct 2005. [DOI: 10.1016/j.molstruc.2004.12.045] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Su G, Pan C, Wang H, Zeng L. Synthesis and Characterization of Some α,β‐Didehydroamino Acid Derivatives. SYNTHETIC COMMUN 2004. [DOI: 10.1081/scc-120027714] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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Synthesis and conformational properties of model dipeptides containing novel axially chiral α,β-didehydroamino acids at the (i+1) position of a β-turn conformation. Tetrahedron 2004. [DOI: 10.1016/j.tet.2004.09.066] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Vass E, Hollósi M, Besson F, Buchet R. Vibrational spectroscopic detection of beta- and gamma-turns in synthetic and natural peptides and proteins. Chem Rev 2003; 103:1917-54. [PMID: 12744696 DOI: 10.1021/cr000100n] [Citation(s) in RCA: 246] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Elemér Vass
- Department of Organic Chemistry, Eötvös Loránd University, H-1518 Budapest 112, P.O. Box 32, Hungary
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Yu CH, Norman MA, Schäfer L, Ramek M, Peeters A, van Alsenoy C. Ab initio conformational analysis of N -formyl l -alanine amide including electron correlation. J Mol Struct 2001. [DOI: 10.1016/s0022-2860(01)00565-8] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Ramek M, Yu CH, Sakon J, Schäfer L. Ab Initio Study of the Conformational Dependence of the Nonplanarity of the Peptide Group. J Phys Chem A 2000. [DOI: 10.1021/jp002498x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Michael Ramek
- Institut für Physikalische und Theoretische Chemie, Technische Universität Graz, A-8010 Graz, Austria
| | - Ching-Hsing Yu
- Department of Chemistry and Biochemistry, University of Arkansas, Fayetteville, Arkansas 72701
| | - Joshua Sakon
- Department of Chemistry and Biochemistry, University of Arkansas, Fayetteville, Arkansas 72701
| | - Lothar Schäfer
- Department of Chemistry and Biochemistry, University of Arkansas, Fayetteville, Arkansas 72701
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Chiu ML, Folcher M, Katoh T, Puglia AM, Vohradsky J, Yun BS, Seto H, Thompson CJ. Broad spectrum thiopeptide recognition specificity of the Streptomyces lividans TipAL protein and its role in regulating gene expression. J Biol Chem 1999; 274:20578-86. [PMID: 10400688 DOI: 10.1074/jbc.274.29.20578] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Microbial metabolites isolated in screening programs for their ability to activate transcription of the tipA promoter (ptipA) in Streptomyces lividans define a class of cyclic thiopeptide antibiotics having dehydroalanine side chains ("tails"). Here we show that such compounds of heterogeneous primary structure (representatives tested: thiostrepton, nosiheptide, berninamycin, promothiocin) are all recognized by TipAS and TipAL, two in-frame translation products of the tipA gene. The N-terminal helix-turn-helix DNA binding motif of TipAL is homologous to the MerR family of transcriptional activators, while the C terminus forms a novel ligand-binding domain. ptipA inducers formed irreversible complexes in vitro and in vivo (presumably covalent) with TipAS by reacting with the second of the two C-terminal cysteine residues. Promothiocin and thiostrepton derivatives in which the dehydroalanine side chains were removed lost the ability to modify TipAS. They were able to induce expression of ptipA as well as the tipA gene, although with reduced activity. Thus, TipA required the thiopeptide ring structure for recognition, while the tail served either as a dispensable part of the recognition domain and/or locked thiopeptides onto TipA proteins, thus leading to an irreversible transcriptional activation. Construction and analysis of a disruption mutant showed that tipA was autogenously regulated and conferred thiopeptide resistance. Thiostrepton induced the synthesis of other proteins, some of which did not require tipA.
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Affiliation(s)
- M L Chiu
- Biozentrum, Department of Microbiology, University of Basel, Klingelbergstrasse 70, CH-4056 Basel, Switzerland
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Cativiela C, Díaz-de-Villegas MD, Gálvez J. Synthesis and chemical resolution of unique α,β-didehydroamino acids with a chiral axis. Tetrahedron Lett 1999. [DOI: 10.1016/s0040-4039(98)02517-9] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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Broda MA, Rzeszotarska B, Smełka L, Pietrzyński G. Conformational investigation of alpha,beta-dehydropeptides. IX. N-Acetyl-(E)-alpha,beta-methylamide: stereoelectronic properties from infrared and theoretical studies. THE JOURNAL OF PEPTIDE RESEARCH : OFFICIAL JOURNAL OF THE AMERICAN PEPTIDE SOCIETY 1998; 52:72-9. [PMID: 9716253 DOI: 10.1111/j.1399-3011.1998.tb00654.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
The Fourier transform infrared spectra of Ac-(E)-deltaAbu-NHMe were analyzed to determine the predominant solution conformation(s) of this (E)-alpha,beta-dehydropeptide-related compound and the electron density perturbation in its amide groups. The measurements were performed in dichloromethane and acetonitrile in the region of mode vs (N-H), amide I, amide II and vs (C(alpha)=Cbeta). The equilibrium geometrical parameters, calculated by a method based on the density functional theory with the B3LYP functional and the 6-31G* basis set, were used to support spectroscopic interpretation and gain some deeper insight into the molecule. The experimental and theoretical data were compared with those of three previously described molecules: isomeric Ac-(Z)-deltaAbu-NHMe, Ac-deltaAla-NHMe, which is deprived of any beta-substituent, and saturated species Ac-Abu-NHMe. The titled compound assumes two conformational states in equilibrium in the DCM solution. One conformer is extended almost fully and like Ac-deltaAla-NHMe is C5 hydrogen-bonded. The other adopts a warped C5 structure similar to that of Ac-(Z)-deltaAbu-NHMe. The C5 hydrogen bond, unlike the H-bond in Ac-deltaAla-NHMe, is disrupted by acetonitrile. The resonance within the N-terminal amide groups in either of the (E)-deltaAbu conformers is not as well developed as the resonance in Ac-Abu-NHMe. However, these N-terminal groups, compared with the other unsaturated compounds, constitute better resonance systems in each conformationally related couple: the C5 hydrogen-bonded Ac-(E)-deltaAbu-NHMe/Ac-deltaAla-NHMe and the warped C5 Ac-(E)-deltaAbu-NHMe/Ac-(Z)-deltaAbu-NHMe. The resonance within the C-terminal groups of the latter couple apparently is similar, but less developed than the resonance in Ac-Abu-NHMe. The electron distribution within the C-terminal group of the hydrogen-bonded C5 (E)-deltaAbu conformer apparently is determined mainly by the electron influx from the C(alpha)=Cbeta double bond.
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Affiliation(s)
- M A Broda
- Department of Organic Chemistry, University of Opole, Poland
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