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Bollu A, Giri P, Dalabehera NR, Asmi AR, Sharma NK. Unnatural Amino Acid: 4-Aminopyrazolonyl Amino Acid Comprising Tri-Peptides Forms Organogel With Co-Solvent (EtOAc:Hexane). Front Chem 2022; 10:821971. [PMID: 35601543 PMCID: PMC9117720 DOI: 10.3389/fchem.2022.821971] [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: 11/25/2021] [Accepted: 03/29/2022] [Indexed: 11/26/2022] Open
Abstract
Ampyrone is an amino-functionalized heterocyclic pyrazolone derivative that possesses therapeutic values such as analgesic, anti-inflammatory, and antipyretics. The chemical structure of ampyrone exhibits excellent hydrogen bonding sites and is considered as the potential scaffold of supramolecular self-assembly. Recently, this molecule has been derived into unnatural amino acids such as aminopyrazolone amino acid and its peptides. This report describes that one of its amino acids, O-alkylated ampyrone, containing hybrid (α/β) peptides forms organogel after sonication at 50–55°C with 0.7–0.9% (w/v) in ethyl acetate: hexane (1:3). The formation/morphology of such organogels is studied by nuclear magnetic resonance Fourier-transform infrared (FT-IR), circular dichroism (CD), scanning electron microscope (SEM), transmission electron microscopy (TEM), powder X-ray diffraction (Powder-XRD), and thermogravimetric analysis (TGA). Energy-minimized conformation of APA-peptides reveals the possibility of intermolecular hydrogen bonding. Hence, APA-peptides are promising peptidomimetics for the organogel-peptides.
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Affiliation(s)
- Amarnath Bollu
- National Institute of Science Education and Research (NISER), Bhubaneswar, India.,Homi Bhabha National Institute (HBNI), Mumbai, India
| | - Prajnanandan Giri
- National Institute of Science Education and Research (NISER), Bhubaneswar, India.,Homi Bhabha National Institute (HBNI), Mumbai, India
| | - Nihar Ranjan Dalabehera
- National Institute of Science Education and Research (NISER), Bhubaneswar, India.,Homi Bhabha National Institute (HBNI), Mumbai, India
| | - Asmita Rani Asmi
- National Institute of Science Education and Research (NISER), Bhubaneswar, India.,Homi Bhabha National Institute (HBNI), Mumbai, India
| | - Nagendra K Sharma
- National Institute of Science Education and Research (NISER), Bhubaneswar, India.,Homi Bhabha National Institute (HBNI), Mumbai, India
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Pyrazole Scaffold Synthesis, Functionalization, and Applications in Alzheimer's Disease and Parkinson's Disease Treatment (2011-2020). Molecules 2021; 26:molecules26051202. [PMID: 33668128 PMCID: PMC7956461 DOI: 10.3390/molecules26051202] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2021] [Revised: 02/20/2021] [Accepted: 02/22/2021] [Indexed: 11/17/2022] Open
Abstract
The remarkable prevalence of pyrazole scaffolds in a versatile array of bioactive molecules ranging from apixaban, an anticoagulant used to treat and prevent blood clots and stroke, to bixafen, a pyrazole-carboxamide fungicide used to control diseases of rapeseed and cereal plants, has encouraged both medicinal and organic chemists to explore new methods in developing pyrazole-containing compounds for different applications. Although numerous synthetic strategies have been developed in the last 10 years, there has not been a comprehensive overview of synthesis and the implication of recent advances for treating neurodegenerative disease. This review first presents the advances in pyrazole scaffold synthesis and their functionalization that have been published during the last decade (2011-2020). We then narrow the focus to the application of these strategies in the development of therapeutics for neurodegenerative diseases, particularly for Alzheimer's disease (AD) and Parkinson's disease (PD).
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Bollu A, Sharma NK. Synthesis and Conformational Analysis of Aminopyrazolonyl
Amino Acid (APA)/Peptides. European J Org Chem 2019. [DOI: 10.1002/ejoc.201801640] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Affiliation(s)
- Amarnath Bollu
- School of Chemical Sciences; National Institute of Science Education and Research (NISER)-Bhubaneswar; Jatni campus 752050 (Odisha) Bhubaneswar- India & HBNI-Mumbai, Mumbai India
| | - Nagendra K. Sharma
- School of Chemical Sciences; National Institute of Science Education and Research (NISER)-Bhubaneswar; Jatni campus 752050 (Odisha) Bhubaneswar- India & HBNI-Mumbai, Mumbai India
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Kusakiewicz-Dawid A, Porada M, Ochędzan-Siodłak W, Broda MA, Bujak M, Siodłak D. Pyrazole amino acids: hydrogen bonding directed conformations of 3-amino-1H-pyrazole-5-carboxylic acid residue. J Pept Sci 2017; 23:716-726. [PMID: 28608410 DOI: 10.1002/psc.3018] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2017] [Revised: 05/24/2017] [Accepted: 05/25/2017] [Indexed: 11/06/2022]
Abstract
A series of model compounds containing 3-amino-1H-pyrazole-5-carboxylic acid residue with N-terminal amide/urethane and C-terminal amide/hydrazide/ester groups were investigated by using NMR, Fourier transform infrared, and single-crystal X-ray diffraction methods, additionally supported by theoretical calculations. The studies demonstrate that the most preferred is the extended conformation with torsion angles ϕ and ψ close to ±180°. The studied 1H-pyrazole with N-terminal amide/urethane and C-terminal amide/hydrazide groups solely adopts this energetically favored conformation confirming rigidity of that structural motif. However, when the C-terminal ester group is present, the second conformation with torsion angles ϕ and ψ close to ±180° and 0°, respectively, is accessible. The conformational equilibrium is observed in NMR and Fourier transform infrared studies in solution in polar environment as well as in the crystal structures of other related compounds. The observed conformational preferences are clearly related to the presence of intramolecular interactions formed within the studied residue. Copyright © 2017 European Peptide Society and John Wiley & Sons, Ltd.
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Affiliation(s)
| | - Monika Porada
- Faculty of Chemistry, University of Opole, Oleska 48, 45-052, Opole, Poland
| | | | - Małgorzata A Broda
- Faculty of Chemistry, University of Opole, Oleska 48, 45-052, Opole, Poland
| | - Maciej Bujak
- Faculty of Chemistry, University of Opole, Oleska 48, 45-052, Opole, Poland
| | - Dawid Siodłak
- Faculty of Chemistry, University of Opole, Oleska 48, 45-052, Opole, Poland
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Schwing K, Gerhards M. Investigations on isolated peptides by combined IR/UV spectroscopy in a molecular beam – structure, aggregation, solvation and molecular recognition. INT REV PHYS CHEM 2016. [DOI: 10.1080/0144235x.2016.1229331] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
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Hellmert M, Müller-Schiffmann A, Peters MS, Korth C, Schrader T. Hybridization of an Aβ-specific antibody fragment with aminopyrazole-based β-sheet ligands displays striking enhancement of target affinity. Org Biomol Chem 2016; 13:2974-9. [PMID: 25613910 DOI: 10.1039/c4ob02411g] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Determining Aβ levels in body fluids remains a powerful tool in the diagnostics of Alzheimer's disease. This report delineates a new supramolecular strategy which increases the affinity of antibodies towards Aβ to make diagnostic procedures more sensitive. A monoclonal antibody IC16 was generated to an N-terminal epitope of Aβ and the variable regions of the heavy and light chains were cloned as a recombinant protein (scFv). A 6 × histidine tag was fused to the C-terminus of IC16-scFv allowing hybridization with a small organic β-sheet binder via Ni-NTA complexation. On the other hand, a multivalent nitrilotriacetic acid (NTA)-equipped trimeric aminopyrazole (AP) derivative was synthesized based on a cyclam platform; and experimental evidence was obtained for efficient Ni(2+)-mediated complex formation with the histidine-tagged antibody species. In a proof of principle experiment the hybrid molecule showed a strong increase in affinity towards Aβ. Thus, the specific binding power of recombinant antibody fragments to their β-sheet rich targets can be conveniently enhanced by non-covalent hybridization with small organic β-sheet binders.
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Affiliation(s)
- Marco Hellmert
- Institute for Organic Chemistry, University of Duisburg-Essen, Universitätsstr. 7, 45117 Essen, Germany.
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Abdel-Latif E, Khalil AGM. Efficient synthesis of some new functionalized 3-amino- and 5-aminopyrazoles derivatives. RESEARCH ON CHEMICAL INTERMEDIATES 2014. [DOI: 10.1007/s11164-014-1551-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Hudson SA, Surade S, Coyne AG, McLean KJ, Leys D, Munro AW, Abell C. Overcoming the limitations of fragment merging: rescuing a strained merged fragment series targeting Mycobacterium tuberculosis CYP121. ChemMedChem 2013; 8:1451-6. [PMID: 23788280 PMCID: PMC4281926 DOI: 10.1002/cmdc.201300219] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2013] [Indexed: 11/08/2022]
Affiliation(s)
- Sean A Hudson
- Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, UK
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Belluti F, Rampa A, Gobbi S, Bisi A. Small-molecule inhibitors/modulators of amyloid-β peptide aggregation and toxicity for the treatment of Alzheimer's disease: a patent review (2010 - 2012). Expert Opin Ther Pat 2013; 23:581-96. [PMID: 23425062 DOI: 10.1517/13543776.2013.772983] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
INTRODUCTION Genetic, physiological, and biochemical data indicate that agglomerates of the 42-amino acid form of the amyloid-β (Aβ(42)) peptide are strongly linked to Alzheimer's disease (AD) etiology and thus represent a particularly attractive target for the development of an effective disease-modifying approach for AD treatment. A plethora of chemical entities able to modulate Aβ(42) self-assembly have been developed in recent years, among them, several are in clinical or preclinical development. AREAS COVERED This review accounts for small-molecule inhibitors of Aβ peptide polymerization and toxicity, reported in the patent literature during the 2010 - 2012 period, and their potential use as disease-modifying therapeutics for AD cure. EXPERT OPINION The earliest pathogenic event is the formation of soluble Aβ oligomers that disrupt synaptic communication. Drug design strategies targeting these primary toxic agents could hold considerable promises for obtaining effective anti-AD drugs candidate. The heterogeneous aggregation of Aβ and the resulting difficulty to structurally characterize the peptide represent important drawbacks.
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Affiliation(s)
- Federica Belluti
- Alma MaterStudiorum-Bologna University, Department of Pharmacy and Biotechnologies, Bologna, Italy.
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Loughlin WA, Tyndall JDA, Glenn MP, Hill TA, Fairlie DP. Update 1 of: Beta-Strand Mimetics. Chem Rev 2011; 110:PR32-69. [DOI: 10.1021/cr900395y] [Citation(s) in RCA: 83] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Affiliation(s)
- Wendy A. Loughlin
- School of Science, Nathan Campus, Griffith University, Brisbane, QLD 4111, Australia, and Division of Chemistry and Structural Biology, Institute for Molecular Bioscience, University of Queensland, Brisbane, QLD 4072, Australia This is a Chemical Reviews Perennial Review. The root paper of this title was published in Chem. Rev. 2004, 104 (12), 6085−6117, DOI: 10.1021/cr040648k; Published (Web) Nov. 4, 2004. Updates to the text appear in red type
| | - Joel D. A. Tyndall
- School of Science, Nathan Campus, Griffith University, Brisbane, QLD 4111, Australia, and Division of Chemistry and Structural Biology, Institute for Molecular Bioscience, University of Queensland, Brisbane, QLD 4072, Australia This is a Chemical Reviews Perennial Review. The root paper of this title was published in Chem. Rev. 2004, 104 (12), 6085−6117, DOI: 10.1021/cr040648k; Published (Web) Nov. 4, 2004. Updates to the text appear in red type
| | - Matthew P. Glenn
- School of Science, Nathan Campus, Griffith University, Brisbane, QLD 4111, Australia, and Division of Chemistry and Structural Biology, Institute for Molecular Bioscience, University of Queensland, Brisbane, QLD 4072, Australia This is a Chemical Reviews Perennial Review. The root paper of this title was published in Chem. Rev. 2004, 104 (12), 6085−6117, DOI: 10.1021/cr040648k; Published (Web) Nov. 4, 2004. Updates to the text appear in red type
| | - Timothy A. Hill
- School of Science, Nathan Campus, Griffith University, Brisbane, QLD 4111, Australia, and Division of Chemistry and Structural Biology, Institute for Molecular Bioscience, University of Queensland, Brisbane, QLD 4072, Australia This is a Chemical Reviews Perennial Review. The root paper of this title was published in Chem. Rev. 2004, 104 (12), 6085−6117, DOI: 10.1021/cr040648k; Published (Web) Nov. 4, 2004. Updates to the text appear in red type
| | - David P. Fairlie
- School of Science, Nathan Campus, Griffith University, Brisbane, QLD 4111, Australia, and Division of Chemistry and Structural Biology, Institute for Molecular Bioscience, University of Queensland, Brisbane, QLD 4072, Australia This is a Chemical Reviews Perennial Review. The root paper of this title was published in Chem. Rev. 2004, 104 (12), 6085−6117, DOI: 10.1021/cr040648k; Published (Web) Nov. 4, 2004. Updates to the text appear in red type
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Hochdörffer K, März-Berberich J, Nagel-Steger L, Epple M, Meyer-Zaika W, Horn AHC, Sticht H, Sinha S, Bitan G, Schrader T. Rational design of β-sheet ligands against Aβ42-induced toxicity. J Am Chem Soc 2011; 133:4348-58. [PMID: 21381732 DOI: 10.1021/ja107675n] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
A β-sheet-binding scaffold was equipped with long-range chemical groups for tertiary contacts toward specific regions of the Alzheimer's Aβ fibril. The new constructs contain a trimeric aminopyrazole carboxylic acid, elongated with a C-terminal binding site, whose influence on the aggregation behavior of the Aβ(42) peptide was studied. MD simulations after trimer docking to the anchor point (F19/F20) suggest distinct groups of complex structures each of which featured additional specific interactions with characteristic Aβ regions. Members of each group also displayed a characteristic pattern in their antiaggregational behavior toward Aβ. Specifically, remote lipophilic moieties such as a dodecyl, cyclohexyl, or LPFFD fragment can form dispersive interactions with the nonpolar cluster of amino acids between I31 and V36. They were shown to strongly reduce Thioflavine T (ThT) fluorescence and protect cells from Aβ lesions (MTT viability assays). Surprisingly, very thick fibrils and a high β-sheet content were detected in transmission electron microscopy (TEM) and CD spectroscopic experiments. On the other hand, distant single or multiple lysines which interact with the ladder of stacked E22 residues found in Aβ fibrils completely dissolve existing β-sheets (ThT, CD) and lead to unstructured, nontoxic material (TEM, MTT). Finally, the triethyleneglycol spacer between heterocyclic β-sheet ligand and appendix was found to play an active role in destabilizing the turn of the U-shaped protofilament. Fluorescence correlation spectroscopy (FCS) and sedimentation velocity analysis (SVA) provided experimental evidence for some smaller benign aggregates of very thin, delicate structure (TEM, MTT). A detailed investigation by dynamic light scattering (DLS) and other methods proved that none of the new ligands acts as a colloid. The evolving picture for the disaggregation mechanism by these new hybrid ligands implies transformation of well-ordered fibrils into less structured aggregates with a high molecular weight. In the few cases where fibrillar components remain, these display a significantly altered morphology and have lost their acute cellular toxicity.
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Affiliation(s)
- Katrin Hochdörffer
- Universität Duisburg-Essen, Fachbereich Chemie, Universitätstrasse 5, 45117 Essen, Germany
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Beheshti S, Lataifeh A, Kraatz HB. Hydrogen-bonding interactions in ferrocene-peptide conjugates containing valine. J Organomet Chem 2011. [DOI: 10.1016/j.jorganchem.2010.10.061] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Müller-Schiffmann A, März-Berberich J, Andreyeva A, Rönicke R, Bartnik D, Brener O, Kutzsche J, Horn AHC, Hellmert M, Polkowska J, Gottmann K, Reymann KG, Funke SA, Nagel-Steger L, Moriscot C, Schoehn G, Sticht H, Willbold D, Schrader T, Korth C. Gesteigerte Wirksamkeit durch Synergismus: Verknüpfung unabhängiger Wirkstoffklassen zu Hybridsubstanzen. Angew Chem Int Ed Engl 2010. [DOI: 10.1002/ange.201004437] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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16
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Müller-Schiffmann A, März-Berberich J, Andreyeva A, Rönicke R, Bartnik D, Brener O, Kutzsche J, Horn AHC, Hellmert M, Polkowska J, Gottmann K, Reymann KG, Funke SA, Nagel-Steger L, Moriscot C, Schoehn G, Sticht H, Willbold D, Schrader T, Korth C. Combining Independent Drug Classes into Superior, Synergistically Acting Hybrid Molecules. Angew Chem Int Ed Engl 2010; 49:8743-6. [DOI: 10.1002/anie.201004437] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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17
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Cocconcelli G, Ghiron C, Haydar S, Micco I, Zanaletti R. Synthesis of Novel 4-Fluoro-2H-pyrazol-3-ylamines. SYNTHETIC COMMUN 2010. [DOI: 10.1080/00397910903277912] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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Wawrzycka-Gorczyca I, Rzeszotarska B, Dżygiel A, Masiukiewicz E, Kozioł AE. Molecular and crystal structure of 5-amino-1H-[1,2,4]triazole-3-carboxylic acid derivatives. Z KRIST-CRYST MATER 2009. [DOI: 10.1524/zkri.218.7.480.20717] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Abstract
The analysis of molecular structures of three derivatives: 5-amino-3-carbomethoxy-1-methyl-1H-[1,2,4]-triazole (1), 1-acetyl-5-amino-3-carbomethoxy-1H-[1,2,4]-triazole (2) and 5-acetylamino-3-carbomethoxy-1-methyl-1H-[1,2,4]triazole (3) indicate the sensitivity of the N2–N1–C5 fragment of the triazole ring to the substitution. Molecular conformations are influenced by several intra- and intermolecular contacts. In all structures very extensive N–H···N/O and C–H(methyl)···O/N net of secondary interactions is formed. This kind of interactions is common in crystal structures which are proton-deficient and for this reason various types of multi-point interactions are forced. Besides, triazole π···π stacking interactions are observed.
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Nagel-Steger L, Demeler B, Meyer-Zaika W, Hochdörffer K, Schrader T, Willbold D. Modulation of aggregate size- and shape-distributions of the amyloid-beta peptide by a designed beta-sheet breaker. EUROPEAN BIOPHYSICS JOURNAL: EBJ 2009; 39:415-22. [PMID: 19238376 DOI: 10.1007/s00249-009-0416-2] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/14/2008] [Revised: 01/26/2009] [Accepted: 02/02/2009] [Indexed: 11/28/2022]
Abstract
A peptide with 42 amino acid residues (Abeta42) plays a key role in the pathogenesis of the Alzheimer's disease. It is highly prone to self aggregation leading to the formation of fibrils which are deposited in amyloid plaques in the brain of diseased individuals. In our study we established a method to analyze the aggregation behavior of the Abeta peptide with a combination of sedimentation velocity centrifugation and enhanced data evaluation software as implemented in the software package UltraScan. Important information which becomes accessible by this methodology is the s-value distribution and concomitantly also the shape-distribution of the Abeta peptide aggregates generated by self-association. With this method we characterized the aggregation modifying effect of a designed beta-sheet breaker molecule. This compound is built from three head-to-tail connected aminopyrazole moieties and represents a derivative of the already described Tripyrazole. By addition of this compound to a solution of the Abeta42 peptide the maximum of the s-value distribution was clearly shifted to smaller s-values as compared to solutions where only the vehicle DMSO was added. This shift to smaller s-values was stable for at least 7 days. The information about size- and shape-distributions present in aggregated Abeta42 solutions was confirmed by transmission electron microscopy and by measurement of amyloid formation by thioflavin T fluorescence.
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Affiliation(s)
- Luitgard Nagel-Steger
- Institute for Physical Biology, Geb.26.12.U1, Heinrich-Heine University Düsseldorf, Universitätsstrasse 1, 40225 Düsseldorf, Germany.
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Fricke H, Gerlach A, Unterberg C, Wehner M, Schrader T, Gerhards M. Wechselwirkung kleiner, geschützter Peptide mit Aminopyrazolderivaten: effektive Verkappung von β-Faltblattmodellen in der Gasphase. Angew Chem Int Ed Engl 2009. [DOI: 10.1002/ange.200802396] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Fricke H, Gerlach A, Unterberg C, Wehner M, Schrader T, Gerhards M. Interactions of Small Protected Peptides with Aminopyrazole Derivatives: The Efficiency of Blocking a β-Sheet Model in the Gas Phase. Angew Chem Int Ed Engl 2009; 48:900-4. [DOI: 10.1002/anie.200802396] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Demeler B, Brookes E, Nagel-Steger L. Analysis of heterogeneity in molecular weight and shape by analytical ultracentrifugation using parallel distributed computing. Methods Enzymol 2009; 454:87-113. [PMID: 19216924 DOI: 10.1016/s0076-6879(08)03804-4] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
Abstract
A computational approach for fitting sedimentation velocity experiments from an analytical ultracentrifuge in a model-independent fashion is presented. This chapter offers a recipe for obtaining high-resolution information for both the shape and the molecular weight distributions of complex mixtures that are heterogeneous in shape and molecular weight and provides suggestions for experimental design to optimize information content. A combination of three methods is used to find the solution most parsimonious in parameters and to verify the statistical confidence intervals of the determined parameters. A supercomputer implementation with a MySQL database back end is integrated into the UltraScan analysis software. The UltraScan LIMS Web portal is used to perform the calculations through a Web interface. The performance and limitations of the method when employed for the analysis of complex mixtures are demonstrated using both simulated data and experimental data characterizing amyloid aggregation.
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Affiliation(s)
- Borries Demeler
- Department of Biochemistry, The University of Texas Health Science Center at San Antonio, San Antonio, Texas, USA
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Laungani AC, Slattery JM, Krossing I, Breit B. Supramolecular bidentate ligands by metal-directed in situ formation of antiparallel beta-sheet structures and application in asymmetric catalysis. Chemistry 2008; 14:4488-502. [PMID: 18449870 DOI: 10.1002/chem.200800359] [Citation(s) in RCA: 92] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The principles of protein structure design, molecular recognition, and supramolecular and combinatorial chemistry have been applied to develop a convergent metal-ion-assisted self-assembly approach that is a very simple and effective method for the de novo design and the construction of topologically predetermined antiparallel beta-sheet structures and self-assembled catalysts. A new concept of in situ generation of bidentate P-ligands for transition-metal catalysis, in which two complementary, monodentate, peptide-based ligands are brought together by employing peptide secondary structure motif as constructing tool to direct the self-assembly process, is achieved through formation of stable beta-sheet motifs and subsequent control of selectivity. The supramolecular structures were studied by (1)H, (31)P, and (13)C NMR spectroscopy, ESI mass spectrometry, X-ray structure analysis, and theoretical calculations. Our initial catalysis results confirm the close relationship between the self-assembled sheet conformations and the catalytic activity of these metallopeptides in the asymmetric rhodium-catalyzed hydroformylation. Good catalyst activity and moderate enantioselectivity were observed for the selected combination of catalyst and substrate, but most importantly the concept of this new methodology was successfully proven. This work presents a perspective interface between protein design and supramolecular catalysis for the design of beta-sheet mimetics and screening of libraries of self-organizing supramolecular catalysts.
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Affiliation(s)
- Andy C Laungani
- Institut für Organische Chemie und Biochemie, Albert-Ludwigs-Universität Freiburg, Freiburg, Germany
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Bourguet E, Correia I, Dorgeret B, Chassaing G, Sicsic S, Ongeri S. Synthesis and conformational studies of pseudopeptides containing an unsymmetrical triazine scaffold. J Pept Sci 2008; 14:596-609. [DOI: 10.1002/psc.944] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Kríz J, Dybal J. Cooperative Hydrogen Bonds of Macromolecules. 3. A Model Study of the Proximity Effect. J Phys Chem B 2007; 111:6118-26. [PMID: 17497914 DOI: 10.1021/jp070203a] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Experimental and theoretical evidence for the proximity effect as a basic mechanism of the hydrogen bond cooperativity was obtained in a model system. Hydrogen bond (HB) interaction between poly(4-vinylpyridine) (PVP) and selected acids as HB donors was studied using PFG NMR self-diffusion measurements, 1H NMR longitudinal relaxation and quantum-mechanical DFT calculations. Bivalent HB donors, such as glutaric (GA) and adipic acid (AA), were compared to univalent donors 4-chlorobutyric acid, 4-acetylbutyric acid and 5-chlorovaleric acid. PFG NMR established substantially larger HB equilibrium constants for AA and, in particular, GA than for univalent donors, thus indicating cooperativity of COOH groups in bivalent donors. According to the values of these constants, the fraction of the transiently bound GA and AA molecules, which are bound by two hydrogen bonds, is 0.70 and 0.63, respectively. This result, which means substantial cooperativity in particular in GA, was then independently verified by a relaxation study comparing longitudinal relaxation rates of univalent and bivalent donors. Analysis of relaxation led to the same probabilities that HB of one COOH group of a bivalent donor will be accompanied by HB of another COOH group of the same molecule, namely 0.70 for GA and 0.63 for AA. Such cooperativity must be due to the proximity effect, i.e., the lowering of the entropy demand of the next binding by the motional restriction imposed by the already existing bonds. This conclusion is in excellent agreement with DFT calculations on the interaction of GA with a model vinylpyridine dimer, which predict preference of double binding of the same GA molecule over that of two GA molecules and show that this preference is due to a substantially lower entropy demand.
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Affiliation(s)
- Jaroslav Kríz
- Institute of Macromolecular Chemistry, Academy of Sciences of the Czech Republic, Heyrovsky Sq. 2, 162 06 Prague 6, Czech Republic.
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26
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Wagger J, Grdadolnik SG, Grošelj U, Meden A, Stanovnik B, Svete J. Chiral solvating properties of (S)-1-benzyl-6-methylpiperazine-2,5-dione. ACTA ACUST UNITED AC 2007. [DOI: 10.1016/j.tetasy.2007.02.010] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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27
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Kusakiewicz-Dawid A, Masiukiewicz E, Rzeszotarska B, Dybała I, Kozioł AE, Broda MA. The Synthesis, Structure and Properties of N-Acetylated Derivatives of Ethyl 3-Amino-1H-pyrazole-4-carboxylate. Chem Pharm Bull (Tokyo) 2007; 55:747-52. [PMID: 17473461 DOI: 10.1248/cpb.55.747] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Ethyl 3-amino-1H-pyrazole-4-carboxylate (1) was yielded through total synthesis and reacted with acetic anhydride to give the acetylated products 2-6. Compounds 1-6 were studied with HPLC, X-ray, FT-IR, (1)H-NMR, (13)C-NMR and MS. Acetylation was carried out in solvents of various polarity, namely; chloroform; dioxane; DMF; acetic anhydride, at room temperature and at boiling points; and in the presence and absence of DMAP. The acetylated products are mainly nitrogen atoms in the ring. The position of the ring proton in the solution was based on NOESY; multinuclear HMBC, HSQC spectra and calculations. For equivalent amounts (1-1.5 mol) of acetic anhydride at room temperature two products of monoacetylation are produced in the ring: 2 and 3, ca. 2 : 1 and at the same time only small amount of the third product of monoacetylated, 5 in DMF, as well the product diacetylated, 4. The greatest amount of the product 4 is produced during the reaction with chloroform. However, in this solvent and in dioxane no product 5 is produced. Compound 2 is, largely, formed in dimethylformamide, in the presence DMAP, 0.2 eq. In the presence of this catalytic base, for the first hour, there is a mixture 2 and 3 to the ratio ca. 95 : 5. With 8 eq of Ac(2)O at reflux, after another hour, the compounds 3, 4 and 6 appear about equal amounts. After a longer time, the compound, which appears most in this mixture is triacetylated derivative 6. The structural and spectroscopic characteristics of compounds 1-6 have been given and the methods for their preparation have been provided.
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Wang W, Weisz K. Characterization of peptide-pyrazole interactions in solution by low-temperature NMR studies. Chemistry 2006; 13:854-61. [PMID: 17086564 DOI: 10.1002/chem.200600591] [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: 11/12/2022]
Abstract
Complexation of the amino- and carboxyl-protected tripeptide Piv-L-Val-L-Val-L-Val-tBu with 3-methylpyrazole and 3-amino-5-methylpyrazole was studied by low-temperature NMR experiments in a freonic solvent. The peptide forms an extended beta-type structure at all temperatures and associates through hydrogen bonding with the two pyrazole-based beta-sheet ligands. A detailed structural characterization of the formed complexes by one- and two-dimensional NMR experiments under slow exchange conditions was made possible by employing very low temperatures. The tripeptide associates to stable antiparallel dimers that are symmetrically capped on both sides by two pyrazole receptors to form 2:2 complexes. Amide groups of two neighboring residues in an extended conformation are involved in cyclic hydrogen bonds to the pyrazole. Based on amide chemical shift changes, the relative strength of intermolecular hydrogen bonds can be assessed and correlated with the electronic effects of the substituents on the pyrazole.
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Affiliation(s)
- Wei Wang
- Freie Universität Berlin, Institut für Organische Chemie, Takustrasse 3, 14195 Berlin, Germany
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Li X, Miltschitzky S, König B. Luminescent pyrimidine hydrazide oligomers with peptide affinity. Bioorg Med Chem 2006; 14:6075-84. [PMID: 16714117 DOI: 10.1016/j.bmc.2006.05.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2006] [Revised: 04/04/2006] [Accepted: 05/03/2006] [Indexed: 10/24/2022]
Abstract
The modular synthesis of pyrimidine oligohydrazides and their peptide binding ability are reported. Ethylene glycol substituents ensure water solubility of the compounds. The pattern of hydrogen bond donors and hydrogen bond acceptors resembles the functionalities of a peptide backbone, and intramolecular hydrogen bonds restrict conformational mobility. The pyrimidine heterocycles show emission at 423 nm if either excited with light of 320 nm or by a FRET process from a nearby Trp residue. This property is useful for the luminescent detection of interactions with peptides and proteins.
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Affiliation(s)
- Xiaoqiang Li
- Institut für Organische Chemie, Universität Regensburg, Germany
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Kríz J, Dybal J, Brus J. Cooperative Hydrogen Bonds of Macromolecules. 2. Two-Dimensional Cooperativity in the Binding of Poly(4-vinylpyridine) to Poly(4-vinylphenol). J Phys Chem B 2006; 110:18338-46. [PMID: 16970455 DOI: 10.1021/jp063837a] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The hydrogen bond interaction of poly(4-vinylphenol) (PVF), ligated by a 20 mol/mol excess of pyridine-d(5) (PD) in tetrahydrofuran-d(8), with poly(4-vinylpyridine) (PVP) was studied using liquid and solid-state NMR and quantum mechanical calculations. Because of its cooperative interaction, PVP substitutes PD in its hydrogen bond with PVF, thus forming a PVF-PVP complex, which gradually precipitates from solution. On the basis of the 1H/13C NMR spin-diffusion experiments and density functional theory quantum calculations, the complex is shown to have the fairly regular structure of a polymer sheet with intermittent H-bond links between PVF and PVP chains. The cooperativity of PVP interaction with PVF was studied by measuring the dependence of the binding degree alpha of PVP on its polymerization degree (P(n), being 10, 17, 30, 36, 48, 65, and 84) at various PVP/PVF molar ratios. The value of alpha was established indirectly by measuring the fraction of liberated PD using its 2H quadrupolar relaxation and pulsed field-gradient spin-echo measurement of self-diffusion. The cooperativity is shown to be of a higher order and two-dimensional, that is, dependent on both the polymerization degree of PVP and its ratio to PVF. A mathematical model of such two-dimensional cooperativity based chiefly on a proximity effect is suggested.
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Affiliation(s)
- Jaroslav Kríz
- Institute of Macromolecular Chemistry, Academy of Sciences of the Czech Republic, Heyrovsky Square 2, 162 06 Prague 6, Czech Republic
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31
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Phillips ST, Piersanti G, Rüth M, Gubernator N, van Lengerich B, Bartlett PA. Facile synthesis of @-tide beta-strand peptidomimetics: improved assembly in solution and on solid phase. Org Lett 2006; 6:4483-5. [PMID: 15548056 DOI: 10.1021/ol048262j] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The synthesis of @-tide beta-strand peptidomimetics has been improved such that oligomers now can be obtained from solution- and solid-phase synthesis protocols approaching the efficiency and flexibility of peptide chemistry. These methods enable the synthesis of @-tide oligomers with a variety of amino acids and with lengths up to 13 units. [reaction: see text]
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Affiliation(s)
- Scott T Phillips
- Center for New Directions in Organic Synthesis, Department of Chemistry, University of California, Berkeley, CA 94720-1460, USA
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32
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Alexander C, Andersson HS, Andersson LI, Ansell RJ, Kirsch N, Nicholls IA, O'Mahony J, Whitcombe MJ. Molecular imprinting science and technology: a survey of the literature for the years up to and including 2003. J Mol Recognit 2006; 19:106-80. [PMID: 16395662 DOI: 10.1002/jmr.760] [Citation(s) in RCA: 776] [Impact Index Per Article: 43.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Over 1450 references to original papers, reviews and monographs have herein been collected to document the development of molecular imprinting science and technology from the serendipitous discovery of Polyakov in 1931 to recent attempts to implement and understand the principles underlying the technique and its use in a range of application areas. In the presentation of the assembled references, a section presenting reviews and monographs covering the area is followed by papers dealing with fundamental aspects of molecular imprinting and the development of novel polymer formats. Thereafter, literature describing attempts to apply these polymeric materials to a range of application areas is presented.
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Affiliation(s)
- Cameron Alexander
- The School of Pharmacy, University of Nottingham, University Park, Nottingham, NG7 2RD, UK
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Appoh FE, Thomas DS, Kraatz HB. Glutamic Acid Dendrimers Attached to a Central Ferrocene Core: Synthesis and Properties. Macromolecules 2005. [DOI: 10.1021/ma050531d] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Francis E. Appoh
- Department of Chemistry, University of Saskatchewan, 110 Science Place, Saskatoon, Saskatchewan S7N 5C9, Canada
| | - Donald S. Thomas
- Department of Chemistry, University of Saskatchewan, 110 Science Place, Saskatoon, Saskatchewan S7N 5C9, Canada
| | - Heinz-Bernhard Kraatz
- Department of Chemistry, University of Saskatchewan, 110 Science Place, Saskatoon, Saskatchewan S7N 5C9, Canada
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Rzepecki P, Schrader T. beta-Sheet ligands in action: KLVFF recognition by aminopyrazole hybrid receptors in water. J Am Chem Soc 2005; 127:3016-25. [PMID: 15740139 DOI: 10.1021/ja045558b] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Little is known about the precise mechanism of action of beta-sheet ligands, hampered by the notorious solubility problems involved with protein misfolding and amyloid formation. Recently the nucleation site for the pathogenic aggregation of the Alzheimer's peptide was identified as the KLVFF sequence in the central region of Abeta. A combination of two aminopyrazole ligands with di- or tripeptides taken from this key fragment now furnished water-soluble Abeta-specific ligands which allow model investigations in water. A detailed conformational analysis provides experimental evidence for an increased beta-sheet content induced in the peptide. Strong indications were also found for the peptide backbone recognition via hydrogen bonds plus hydrophobic contributions between aminopyrazole nuclei and Phe residues. The affinity of these new ligands toward the KKLVFF fragment is highly dependent on their sequence and composition from natural and artificial amino acids. Thus, for the first time, detailed insight is gained into the complexation of beta-sheet ligands with model peptides taken directly from Abeta.
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Affiliation(s)
- Petra Rzepecki
- Department of Chemistry, Philipps-Universität Marburg, Hans-Meerwein-Strasse, 35032 Marburg, Germany
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Meyer M, Frémond L, Tabard A, Espinosa E, Vollmer GY, Guilard R, Dory Y. Synthesis, characterization and X-ray crystal structures of cyclam derivatives. Part VI. Proton binding studies of a pyridine-strapped 5,12-dioxocyclam based macrobicycle. NEW J CHEM 2005. [DOI: 10.1039/b410260f] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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36
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Mandl CP, König B. Luminescent Crown Ether Amino Acids: Selective Binding toN-terminal Lysine in Peptides. J Org Chem 2005; 70:670-4. [PMID: 15651816 DOI: 10.1021/jo048105y] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Crown ether amino acids (CEAAs) with a luminescent phthalic ester or phthalimide moiety have been prepared. Simple peptide chemistry covalently tethers the macrocycles to give ditopic ammonium-ion binders. The binding events of both crown ether groups are monitored independently by changes of their specific emission properties. The affinity of the bis-CEAA to bis-ammonium ions is distance dependent, which allows distinguishing between isomeric small peptides containing a lysine residue in different positions.
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Affiliation(s)
- Christian P Mandl
- Institut für Organische Chemie, Universität Regensburg, Regensburg, Germany
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37
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Ferrocenoyl peptides with sulfur-containing side chains: synthesis, solid state and solution structures. J Organomet Chem 2004. [DOI: 10.1016/j.jorganchem.2004.10.002] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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38
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Affiliation(s)
- Wendy A Loughlin
- School of Science, Nathan Campus, Griffith University, Brisbane, QLD 4111, Australia.
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39
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Rzepecki P, Nagel-Steger L, Feuerstein S, Linne U, Molt O, Zadmard R, Aschermann K, Wehner M, Schrader T, Riesner D. Prevention of Alzheimer's Disease-associated Aβ Aggregation by Rationally Designed Nonpeptidic β-Sheet Ligands. J Biol Chem 2004; 279:47497-505. [PMID: 15322133 DOI: 10.1074/jbc.m405914200] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
A new concept is introduced for the rational design of beta-sheet ligands, which prevent protein aggregation. Oligomeric acylated aminopyrazoles with a donor-acceptor-donor (DAD) hydrogen bond pattern complementary to that of a beta-sheet efficiently block the solvent-exposed beta-sheet portions in Abeta-(1-40) and thereby prevent formation of insoluble protein aggregates. Density gradient centrifugation revealed that in the initial phase, the size of Abeta aggregates was efficiently kept between the trimeric and 15-meric state, whereas after 5 days an additional high molecular weight fraction appeared. With fluorescence correlation spectroscopy (FCS) exactly those two, i.e. a dimeric aminopyrazole with an oxalyl spacer and a trimeric head-to-tail connected aminopyrazole, of nine similar aminopyrazole ligands were identified as efficient aggregation retardants whose minimum energy conformations showed a perfect complementarity to a beta-sheet. The concentration dependence of the inhibitory effect of a trimeric aminopyrazole derivative allowed an estimation of the dissociation constant in the range of 10(-5) m. Finally, electrospray ionization mass spectrometry (ESI-MS) was used to determine the aggregation kinetics of Abeta-(1-40) in the absence and in the presence of the ligands. From the comparable decrease in Abeta monomer concentration, we conclude that these beta-sheet ligands do not prevent the initial oligomerization of monomeric Abeta but rather block further aggregation of spontaneously formed small oligomers. Together with the results from density gradient centrifugation and fluorescence correlation spectroscopy it is now possible to restrict the approximate size of soluble Abeta aggregates formed in the presence of both inhibitors from 3- to 15-mers.
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Affiliation(s)
- Petra Rzepecki
- Department of Chemistry, Philipps-Universität Marburg, Hans-Meerwein-Strasse, 35032 Marburg, USA
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40
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Copper assisted acetylation of 3-amino-5-methylpyrazole: first copper complex of an aminopyrazole. INORG CHEM COMMUN 2004. [DOI: 10.1016/j.inoche.2003.11.031] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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41
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Cernovská K, Kemter M, Gallmeier HC, Rzepecki P, Schrader T, König B. PEG-supported synthesis of pyrazole oligoamides with peptide β-sheet affinity. Org Biomol Chem 2004; 2:1603-11. [PMID: 15162212 DOI: 10.1039/b401968g] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Pyrazole amino acid oligoamides were prepared on polyethylene glycol starting from nitro pyrazole carboxylic acids or protected pyrazole amino acids. The polymer support facilitates product isolation during synthesis and makes the target oligoamides soluble in chloroform and water. This allows the determination of their binding properties towards peptides. Moderate affinity, which increases with the number of pyrazole units, is observed in chloroform and water.
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42
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Dzygiel A, Rzeszotarska B, Masiukiewicz E, Cmoch P, Kamieński B. Synthesis, Structure and Properties of N-Acetylated Derivatives of Methyl 5-Amino-1H-[1,2,4]triazole-3-carboxylate. Chem Pharm Bull (Tokyo) 2004; 52:192-8. [PMID: 14758003 DOI: 10.1248/cpb.52.192] [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: 11/22/2022]
Abstract
Methyl 5-amino-1H-[1,2,4]triazole-3-carboxylate hydrochloride (1). and free ester (2). were obtained and 2 was reacted with Ac(2)O to give the acetylated products 3-6. Compounds 1-6 were studied using HPLC, GC-MS, FTIR and multinuclear NMR spectroscopy, including the cross-polarisation magic angle spinning (CPMAS) technique. The results of the acetylation of 2 were compared to those of the acetylation of 5-amino-1H-[1,2,4]triazole, and for 2 a significant decrease in the susceptibility to acetylation was found. The reaction of 2 with Ac(2)O at 20 degrees C, regardless of the amount and the concentration of the latter, including neat Ac(2)O, proceeds fully regioselectively and leads to one product: methyl 1-acetyl-5-amino-1H-[1,2,4]triazole-3-carboxylate (3). In sharp contrast to 5-amino-1H-[1,2,4]triazole, neither an additional monoacetylated isomer, whether annular or exocyclic, nor any diacetylated derivative could be detected. The diacetylation of 2 requires the process to be carried out in neat boiling Ac(2)O and, as in the case of 5-amino-1H-[1,2,4]triazole, gives two diacetylated isomers. These are methyl 1-acetyl-3-(acetylamino)-1H-[1,2,4]triazole-5-carboxylate (4) and 1-acetyl-5-(acetylamino)-1H-[1,2,4]triazole-3-carboxylate (5). Hypothetical pathways of their formation have been suggested. A mixture of 4 and 5 upon hydrolysis of the ring acetyl group gives the monoacetylated derivative methyl 5-(acetylamino)-1H-[1,2,4]triazole-3-carboxylate (6). The spectroscopic, structural and conformational characteristics of compounds 1-6 have been given and methods for their preparation have been provided.
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Affiliation(s)
- Anetta Dzygiel
- Institute of Chemistry, University of Opole, Opole, Poland
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Gerhards M, Unterberg C, Gerlach A, Jansen A. β-sheet model systems in the gas phase: Structures and vibrations of Ac–Phe–NHMe and its dimer (Ac–Phe–NHMe)2. Phys Chem Chem Phys 2004. [DOI: 10.1039/b316001g] [Citation(s) in RCA: 101] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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45
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Bediako-Amoa I, Sutherland TC, Li CZ, Silerova R, Kraatz HB. Electrochemical and Surface Study of Ferrocenoyl Oligopeptides. J Phys Chem B 2003. [DOI: 10.1021/jp0368785] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Irene Bediako-Amoa
- Department of Chemistry, University of Saskatchewan, 110 Science Place, Saskatoon, Saskatchewan, Canada S7N 5C9
| | - Todd C. Sutherland
- Department of Chemistry, University of Saskatchewan, 110 Science Place, Saskatoon, Saskatchewan, Canada S7N 5C9
| | - Chen-Zhong Li
- Department of Chemistry, University of Saskatchewan, 110 Science Place, Saskatoon, Saskatchewan, Canada S7N 5C9
| | - Roberta Silerova
- Department of Chemistry, University of Saskatchewan, 110 Science Place, Saskatoon, Saskatchewan, Canada S7N 5C9
| | - Heinz-Bernhard Kraatz
- Department of Chemistry, University of Saskatchewan, 110 Science Place, Saskatoon, Saskatchewan, Canada S7N 5C9
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First zinc complex of an amino acid pyrazole conjugate: synthesis and crystal structure of {Zn[3-(Ac-Phe)-5-methyl-pyrazole]2}2(ClO4)4. INORG CHEM COMMUN 2003. [DOI: 10.1016/s1387-7003(03)00068-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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47
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Unterberg C, Gerlach A, Schrader T, Gerhards M. Structure of the protected dipeptide Ac-Val-Phe-OMe in the gas phase: Towards a β-sheet model system. J Chem Phys 2003. [DOI: 10.1063/1.1565110] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
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48
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van Staveren DR, Weyhermüller T, Metzler-Nolte N. Organometallic β-turn mimetics. A structural and spectroscopic study of inter-strand hydrogen bonding in ferrocene and cobaltocenium conjugates of amino acids and dipeptides. Dalton Trans 2003. [DOI: 10.1039/b208363a] [Citation(s) in RCA: 95] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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50
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Affiliation(s)
- Günter Wulff
- Institute of Organic Chemistry and Macromolecular Chemistry, Heinrich-Heine-University Düsseldorf, Universitätsstr. 1, D-40225 Düsseldorf, Germany.
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