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Lee HJ, Liu SW, Sulyok-Eiler M, Harmat V, Farkas V, Bánóczi Z, El Khabchi M, Shawn Fan HJ, Hirao K, Song JW. Neighbor effect on conformational spaces of alanine residue in azapeptides. Heliyon 2024; 10:e33159. [PMID: 39021983 PMCID: PMC11253059 DOI: 10.1016/j.heliyon.2024.e33159] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2024] [Revised: 06/10/2024] [Accepted: 06/14/2024] [Indexed: 07/20/2024] Open
Abstract
The conformational properties of Alanine (Ala) residue have been investigated to understand protein folding and develop force fields. In this work, we examined the neighbor effect on the conformational spaces of Ala residue using model azapeptides, Ac-Ala-azaGly-NHMe (3, AaG), and Ac-azaGly-Ala-NHMe (4, aGA1). Ramachandran energy maps were generated by scanning (φ, ψ) dihedral angles of the Ala residues in models with the fixed dihedral angles (φ = ±90°, ψ = ±0° or ±180°) of azaGly residue using LCgau-BOP and LCgau-BOP + LRD functionals in the gas and water phases. The integral-equation-formalism polarizable continuum model (IEF-PCM) and a solvation model density (SMD) were employed to mimic the solvation effect. The most favorable conformation of Ala residue in azapeptide models is found as the polyproline II (βP), inverse γ-turn (γ'), β-sheet (βS), right-handed helix (αR), or left-handed helix (αL) depending on the conformation of neighbor azaGly residue in isolated form. Solvation methods exhibit that the Ala residue favors the βP, δR, and αR conformations regardless of its position in azapeptides 3 and 4 in water. Azapeptide 5, Ac-azaGly-Ala-NH2 (aGA2), was synthesized to evaluate the theoretical results. The X-ray structure showed that azaGly residue adopts the polyproline II (βP) and Ala residue adopts the right-handed helical (αR) structure in aGA2. The conformational preferences of aGA2 and the dimer structure of aGA2 based on the X-ray structure were examined to assess the performance of DFT functionals. In addition, the local minima of azapeptide 6, Ac-Phe-azaGly-NH2 (FaG), were compared with the previous experimental results. SMD/LCgau-BOP + LRD methods agreed well with the reported experimental results. The results suggest the importance of weak dispersion interactions, neighbor effect, and solvent influence in the conformational preferences of Ala residue in model azapeptides.
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Affiliation(s)
- Ho-Jin Lee
- Division of Natural and Mathematics Sciences, LeMoyne-Own College, Memphis, TN, 38126, USA
- Department of Natural Sciences, Southwest Tennessee Community College, Memphis, TN, 38015, USA
| | - Shi-Wei Liu
- College of Chemical Engineering, Sichuan University of Science and Engineering, Zigong City, Sichuan Province, 64300, PR China
| | - Máté Sulyok-Eiler
- Laboratory of Structural Biology and Chemistry, Institute of Chemistry, Eötvös Loránd University, Budapest, Hungary
- Hevesy György PhD School of Chemistry, Eötvös Loránd University, Budapest, Hungary
| | - Veronika Harmat
- Laboratory of Structural Biology and Chemistry, Institute of Chemistry, Eötvös Loránd University, Budapest, Hungary
- HUN-REN - ELTE Protein Modeling Research Group, Budapest, Hungary
| | - Viktor Farkas
- Laboratory of Structural Biology and Chemistry, Institute of Chemistry, Eötvös Loránd University, Budapest, Hungary
- HUN-REN - ELTE Protein Modeling Research Group, Budapest, Hungary
| | - Zoltán Bánóczi
- Department of Organic Chemistry, Institute of Chemistry, ELTE Eötvös Loránd University, 1117, Budapest, Hungary
- HUN-REN-ELTE Research Group of Peptide Chemistry, 1117, Budapest, Hungary
| | - Mouna El Khabchi
- LIMAS, Faculty of Sciences Dhar El Mahraz, University Sidi Mohamed Ben Abdallah, Fez, Morocco
| | - Hua-Jun Shawn Fan
- College of Chemical Engineering, Sichuan University of Science and Engineering, Zigong City, Sichuan Province, 64300, PR China
| | - Kimihiko Hirao
- Fukui Institute for Fundamental Chemistry, Kyoto University, Takano, Nishihiraki-cho 34-4, Sakyo-ku, Kyoto, 606-8103, Japan
| | - Jong-Won Song
- Department of Chemistry Education, Daegu University, Daegudae-ro 201, Gyeongsan-si, Gyeongsangbuk-do, 38453, Republic of Korea
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2
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El Khabchi M, Mcharfi M, Benzakour M, Fitri A, Benjelloun AT, Song JW, Lee KB, Lee HJ. Computational Investigation of Conformational Properties of Short Azapeptides: Insights from DFT Study and NBO Analysis. Molecules 2023; 28:5454. [PMID: 37513326 PMCID: PMC10386235 DOI: 10.3390/molecules28145454] [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: 06/09/2023] [Revised: 07/05/2023] [Accepted: 07/12/2023] [Indexed: 07/30/2023] Open
Abstract
Azapeptides have gained much attention due to their ability to enhance the stability and bioavailability of peptide drugs. Their structural preferences, essential to understanding their function and potential application in the peptide drug design, remain largely unknown. In this work, we systematically investigated the conformational preferences of three azaamino acid residues in tripeptide models, Ac-azaXaa-Pro-NHMe [Xaa = Asn (4), Asp (5), Ala (6)], using the popular DFT functionals, B3LYP and B3LYP-D3. A solvation model density (SMD) was used to mimic the solvation effect on the conformational behaviors of azapeptides in water. During the calculation, we considered the impact of the amide bond in the azapeptide models on the conformational preferences of models 4-6. We analyzed the effect of the HB between the side-chain main chain and main-chain main-chain on the conformational behaviors of azapeptides 4-6. We found that the predicted lowest energy conformation for the three models differs depending on the calculation methods. In the gas phase, B3LYP functional indicates that the conformers tttANP-1 and tttADP-1 of azapeptides 4 and 5 correspond to the type I of β-turn, the lowest energy conformation with all-trans amide bonds. Considering the dispersion correction, B3LYP-D3 functional predicts the conformers tctANP-2 and tctADP-3 of azapeptide 4 and 5, which contain the cis amide bond preceding the Pro residue, as the lowest energy conformation in the gas phase. The results imply that azaAsx and Pro residues may involve cis-trans isomerization in the gas phase. In water, the predicted lowest energy conformer of azapeptides 4 and 5 differs from the gas phase results and depends on the calculational method. For azapeptide 6, regardless of calculation methods and phases, tttAAP-1 (β-I turn) is predicted as the lowest energy conformer. The results imply that the effect of the side chain that can form HBs on the conformational preferences of azapeptides 4 and 5 may not be negligible. We compared the theoretical results of azaXaa-Pro models with those of Pro-azaXaa models, showing that incorporating azaamino acid residue in peptides at different positions can significantly impact the folding patterns and stability of azapeptides.
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Affiliation(s)
- Mouna El Khabchi
- LIMAS, Department of Chemistry, Faculty of Sciences Dhar El Mahraz, Sidi Mohamed Ben Abdallah University, Fez 30000, Morocco
| | - Mohammed Mcharfi
- LIMAS, Department of Chemistry, Faculty of Sciences Dhar El Mahraz, Sidi Mohamed Ben Abdallah University, Fez 30000, Morocco
| | - Mohammed Benzakour
- LIMAS, Department of Chemistry, Faculty of Sciences Dhar El Mahraz, Sidi Mohamed Ben Abdallah University, Fez 30000, Morocco
| | - Asmae Fitri
- LIMAS, Department of Chemistry, Faculty of Sciences Dhar El Mahraz, Sidi Mohamed Ben Abdallah University, Fez 30000, Morocco
| | - Adil Touimi Benjelloun
- LIMAS, Department of Chemistry, Faculty of Sciences Dhar El Mahraz, Sidi Mohamed Ben Abdallah University, Fez 30000, Morocco
| | - Jong-Won Song
- Department of Chemistry Education, Daegu University, Daegudae-ro 201, Gyeongsan-si 38453, Republic of Korea
| | - Kang-Bong Lee
- Climate and Environmental Research Institute, Korea Institute of Science & Technology, Hwarang-ro 14-gil 5, Seoul 02792, Republic of Korea
| | - Ho-Jin Lee
- Department of Natural Sciences, Southwest Tennessee Community College, Memphis, TN 38134, USA
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Arcoria PJ, Etzkorn FA. A fluoro-alkene mimic of Gly- trans-Pro produces a stable collagen triple helix. Org Biomol Chem 2023; 21:4039-4051. [PMID: 37114339 DOI: 10.1039/d3ob00110e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/29/2023]
Abstract
We report the first experimental evidence for a fluoro-alkene amide isostere participating in n→π* donation, which stabilizes the collagen triple helix. Of the three amide positions in canonical collagen-like peptides, Gly-Pro, Pro-Hyp, and Hyp-Gly, triple helix stability stands to benefit from substitution of only the isomerizable 3° Gly-Pro amide bond with a trans-locked fluoro-alkene. A (Z)-fluoro-alkene isostere of Gly-trans-Pro was synthesized, and its effect on the thermostability of a collagen-like peptide triple helix was measured. The mixture of enantiomers, Boc-Gly-Ψ[(Z)CFC]-L/D-Pro-OH, was synthesized in 8 steps with 27% overall yield, and the Fmoc-Gly-Ψ[(Z)CFC]-L/D-Pro-Hyp-OBn diastereomers were separated. The Gly-Ψ[(Z)CFC]-Pro isostere installed in a collagen-like peptide forms a stable triple helix. By CD, the thermal melting (Tm) value of the fluoro-alkene peptide was +42.2 ± 0.4 °C, and the Tm value of the control peptide was +48.4 ± 0.5 °C, a difference in stability of ΔTm -6.2 °C. Deshielding of the fluorine nucleus in the 19F NMR spectra is evidence of a stabilizing n→π* electronic interaction.
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Affiliation(s)
- Paul J Arcoria
- Department of Chemistry, Virginia Tech, Blacksburg, VA, 24061, USA.
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Arcoria PJ, Ware RI, Makwana SV, Troya D, Etzkorn FA. Conformational Analysis of Fluoro-, Chloro-, and Proteo-Alkene Gly-Pro and Pro-Pro Isosteres to Mimic Collagen. J Phys Chem B 2021; 126:217-228. [PMID: 34968406 DOI: 10.1021/acs.jpcb.1c09180] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Collagen is the most abundant human protein, with the canonical sequence (Gly-Pro-Hyp)n in its triple helix region. Cis-trans isomerization of the Xaa-Pro amide has made two of these amide bonds the target of alkene replacement: the Gly-Pro and the Pro-Hyp positions. The conformations of Gly-Pro and Pro-Pro (as a Pro-Hyp model) fluoro-, chloro-, and proteo-alkene mimic models were investigated computationally to determine whether these alkenes can stabilize the polyproline type II (PPII) conformation of collagen. Second-order Møller-Plesset (MP2) calculations with various basis sets were used to perform the conformational analyses and locate stationary points. The calculation results predict that fluoro- and chloro-alkene mimics of Gly-Pro and Pro-Pro can participate in n→π* donation to stabilize PPII conformations, yet they are poor n→π* acceptors, shifting the global minima away from PPII conformations. For the proteo-alkene mimics, the lack of significant n→π* interactions and unstable PPII-like geometries explains their known destabilization of the triple helix in collagen-like peptides.
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Affiliation(s)
- Paul J Arcoria
- Department of Chemistry, Virginia Tech, Blacksburg, Virginia 24061, United States
| | - Rachel I Ware
- Department of Chemistry, Virginia Tech, Blacksburg, Virginia 24061, United States
| | - Sunny V Makwana
- Department of Chemistry, Virginia Tech, Blacksburg, Virginia 24061, United States
| | - Diego Troya
- Department of Chemistry, Virginia Tech, Blacksburg, Virginia 24061, United States
| | - Felicia A Etzkorn
- Department of Chemistry, Virginia Tech, Blacksburg, Virginia 24061, United States
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Sahariah B, Sarma BK. Deciphering the Backbone Noncovalent Interactions that Stabilize Polyproline II Conformation and Reduce cis Proline Abundance in Polyproline Tracts. J Phys Chem B 2021; 125:13394-13405. [PMID: 34851647 DOI: 10.1021/acs.jpcb.1c07875] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Proline (Pro) has a higher propensity to adopt cis amide geometry than the other natural amino acids, and a poly-Pro (poly-P) tract can adopt either a polyproline I (PPI, all cis amide) or a polyproline II (PPII, all trans amide) helical conformation. Recent studies have revealed a reduced abundance of cis amide geometry among the inner Pro residues of a poly-P tract. However, the forces that stabilize the polyproline helices and the reason for the higher trans amide propensity of the inner Pro residues of a poly-P tract are poorly understood. Herein, we have studied both Pro and non-Pro PPII helical sequences and identified the backbone noncovalent interactions that are crucial to the higher stability of the trans Pro-amide geometry and the preference for a PPII helical conformation. We show the presence of reciprocal CO···CO interactions that extend over the whole PPII helical region. Interestingly, the CO···CO interactions strengthen with the increase in the PPII helical chain length and the inner CO groups possess stronger CO···CO interactions, which could explain the reduced cis abundance of the inner Pro residues of a poly-P tract. We also identified a much stronger (∼0.9 kcal·mol-1) nO → σ*Cα-Cβ interaction between the N-terminal CO oxygen lone pair and the antibonding orbital (σ*) of their Cα-Cβ bonds. As the nO → σ*Cα-Cβ interaction is possible only in the trans isomers of Pro, this interaction should be crucial for the stabilization of a PPII helix. Finally, an unusual nN(amide) → σ*C-N interaction (∼0.3 kcal·mol-1) was observed between the peptidic nitrogen lone pair (nN) and the antibonding orbital (σ*C-N) of the subsequent C-terminal peptide C-N bond. We propose a cumulative effect of these interactions in the stabilization of a PPII helix.
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Affiliation(s)
- Biswajit Sahariah
- New Chemistry Unit, Jawaharlal Nehru Centre for Advanced Scientific Research (JNCASR), Jakkur, Bangalore 560064, India
| | - Bani Kanta Sarma
- New Chemistry Unit, Jawaharlal Nehru Centre for Advanced Scientific Research (JNCASR), Jakkur, Bangalore 560064, India
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Garsi JB, Aguiar PM, Hanessian S. Design of Pseudodiproline Dimers as Mimetics of Pro-Pro Units: Stereocontrolled Synthesis, Configurational Relevance, and Structural Properties. J Org Chem 2021; 86:16834-16847. [PMID: 34749500 DOI: 10.1021/acs.joc.1c02061] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Stereocontrolled methods are described for the synthesis of hitherto unreported pseudodiproline dimers in which a cyclopentane carboxylic acid is linked to a pyrrolidine residue by a stereochemically defined hydroxymethylene tether. These proline-cyclopentane (Pro-Cyp) dimers have interesting structural characteristics as seen in their X-ray crystal structures as well as their nuclear magnetic resonance (NMR) spectra in CDCl3. They can be considered to be novel Pro-Pro mimetics, which can be used to replace natural diproline sequences with potential applications in medicinal chemistry. They also represent a new concept in the peptidomimetic design of chimeric proline-based amino acids as carbocyclic hydroxyethylene isosteres of inhibitor molecules, in which the stereodefined bridging hydroxyl group can simulate a tetrahedral intermediate in an enzyme complex.
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Affiliation(s)
- Jean-Baptiste Garsi
- Department of Chemistry, Université de Montréal, 1375 Ave. Thérèse-Lavoie-Roux, Montréal, H2V 0B3 QC, Canada
| | - Pedro M Aguiar
- Department of Chemistry, Université de Montréal, 1375 Ave. Thérèse-Lavoie-Roux, Montréal, H2V 0B3 QC, Canada
| | - Stephen Hanessian
- Department of Chemistry, Université de Montréal, 1375 Ave. Thérèse-Lavoie-Roux, Montréal, H2V 0B3 QC, Canada
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Deka JKR, Sahariah B, Baruah K, Bar AK, Sarma BK. Conformational control of N-methyl-N,N′-diacylhydrazines by noncovalent carbon bonding in solution. Chem Commun (Camb) 2020; 56:4874-4877. [DOI: 10.1039/d0cc00943a] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Unusual N(amide)⋯C–X noncovalent carbon bonding interactions stabilize the trans–cis (t–c) amide bond rotamers of N-methyl-N,N′-diacylhydrazines over the expected trans–trans (t–t) rotamers in solution.
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Affiliation(s)
| | - Biswajit Sahariah
- Department of Chemistry
- School of Natural Sciences
- Shiv Nadar University
- Dadri
- India
| | - Kalpita Baruah
- Department of Chemistry
- School of Natural Sciences
- Shiv Nadar University
- Dadri
- India
| | - Arun Kumar Bar
- Department of Chemistry
- Indian Institute of Science Education and Research (IISER) Tirupati
- Tirupati 517507
- India
| | - Bani Kanta Sarma
- New Chemistry Unit
- Jawaharlal Nehru Centre for Advanced Scientific Research (JNCASR)
- Bangalore 560064
- India
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Harris T, Chenoweth DM. Sterics and Stereoelectronics in Aza-Glycine: Impact of Aza-Glycine Preorganization in Triple Helical Collagen. J Am Chem Soc 2019; 141:18021-18029. [DOI: 10.1021/jacs.9b05524] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Affiliation(s)
- Trevor Harris
- Department of Chemistry, University of Pennsylvania, 231 South 34th Street, Philadelphia, Pennsylvania 19104-6323, United States
| | - David M. Chenoweth
- Department of Chemistry, University of Pennsylvania, 231 South 34th Street, Philadelphia, Pennsylvania 19104-6323, United States
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