101
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Efficient access to N-protected derivatives of (R,R,R)- and (S,S,S)-octahydroindole-2-carboxylic acid by HPLC resolution. ACTA ACUST UNITED AC 2007. [DOI: 10.1016/j.tetasy.2007.09.006] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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102
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Kiss L, Mangelinckx S, Sillanpää R, Fülöp F, De Kimpe N. An Easy Stereoselective Access to β,γ-Aziridino α-Amino Ester Derivatives via Mannich Reaction of Benzophenone Imines of Glycine Esters with N-Sulfonyl α-Chloroaldimines. J Org Chem 2007; 72:7199-206. [PMID: 17705431 DOI: 10.1021/jo0710634] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Mannich-type addition of benzophenone imine glycinates across newly synthesized N-(p-toluenesulfonyl) alpha-chloroaldimines afforded gamma-chloro-alpha,beta-diamino ester derivatives with moderate diastereoselectivity as separable mixtures of anti and syn diastereomers. The gamma-chloro-alpha,beta-diamino esters were efficiently cyclized under basic conditions to the corresponding beta,gamma-aziridino alpha-amino ester derivatives, representing a new class of conformationally constrained heterocyclic alpha,beta-diamino acid derivatives. The relative configuration of the aziridines was determined via X-ray diffraction analysis. Mechanisms and intermediate transition states to explain the stereochemical outcome of the Mannich reaction with different substrates or under different conditions are proposed. The synthetic importance of the beta,gamma-aziridino alpha-amino ester derivatives is demonstrated by their conversion into the corresponding Boc-protected derivatives and ring opening reactions to alpha,beta-diamino esters and a gamma-amino alpha,beta-unsaturated amino ester.
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Affiliation(s)
- Loránd Kiss
- Department of Organic Chemistry, Faculty of Bioscience Engineering, Ghent University, Coupure Links 653, B-9000 Ghent, Belgium
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103
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Abstract
A straightforward synthesis of 8-azabicyclo[3.2.1]octane-1-carboxylic acid, a new proline analogue with a bicyclic structure, is described. The procedure makes use of readily available starting materials and involves simple, high-yielding transformations.
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104
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Shao X, Gao Y, Zhu C, Liu X, Yao J, Cui Y, Wang R. Conformational analysis of endomorphin-2 analogs with phenylalanine mimics by NMR and molecular modeling. Bioorg Med Chem 2007; 15:3539-47. [PMID: 17368034 DOI: 10.1016/j.bmc.2007.02.050] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2006] [Revised: 02/22/2007] [Accepted: 02/23/2007] [Indexed: 11/20/2022]
Abstract
We investigated a series of conformations of endomorphin-2 (EM-2) analogs substituted by phenylglycine (Phg) and homophenylalanine (Hfe) in the position 3 or 4 by two-dimensional (1)H NMR spectroscopy and molecular modeling. Evaluating the aromatic interactions and the dihedral angles in these phenylalanine mimics, we have observed that the conformations in trans isomer have varied from extended to folded as bioactivity decreases. It is suggested that the flexibility of aromatic side chain affects the backbone of EM-2 to adopt folded structures, which may block the ligands in binding to micro-opioid receptor.
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Affiliation(s)
- Xuan Shao
- State Key Laboratory of Applied Organic Chemistry, Institute of Biochemistry and Molecular Biology, School of Life Science, Lanzhou University, Lanzhou 730000, People's Republic of China
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105
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Zanuy D, Jiménez AI, Cativiela C, Nussinov R, Alemán C. Use of constrained synthetic amino acids in beta-helix proteins for conformational control. J Phys Chem B 2007; 111:3236-42. [PMID: 17388467 DOI: 10.1021/jp065025k] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
A highly constrained amino acid has been introduced in the turn region of a beta-helix to increase the conformational stability of the native fold for nanotechnological purposes. The influence of this specific amino acid replacement in the final organization of beta-helix motifs has been evaluated by combining ab initio first-principles calculations on model systems and molecular dynamics simulations of entire peptide segments. The former methodology, which has been applied to a sequence containing three amino acids, has been used to develop adjusted templates. Calculations indicated that 1-amino-2,2-diphenylcyclopropanecarboxylic acid, a constrained cyclopropane analogue of phenylalanine, exhibits a strong tendency to form and promote folded conformations. On the other hand, molecular dynamics simulations are employed to probe the ability of such a synthetic amino acid to enhance the conformational stability of the beta-helix motif, which is the first requirement for further protein nanoengineering. A highly regular segment from a naturally occurring beta-helix protein was selected as a potential nanoconstruct module. Simulations of wild type and mutated segments revealed that the ability of the phenylalanine analogue to nucleate turn conformations enhances the conformational stability of the beta-helix motif in isolated peptide segments.
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Affiliation(s)
- David Zanuy
- Departament d'Enginyeria Química, ETSEIB, Universitat Politècnica de Catalunya, Diagonal 647, 08028 Barcelona, Spain
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106
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Cativiela C, Díaz-de-Villegas MD. Recent progress on the stereoselective synthesis of acyclic quaternary α-amino acids. ACTA ACUST UNITED AC 2007. [DOI: 10.1016/j.tetasy.2007.02.003] [Citation(s) in RCA: 290] [Impact Index Per Article: 17.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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107
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Casanovas J, Zanuy D, Nussinov R, Alemán C. Intrinsic conformational characteristics of alpha,alpha-diphenylglycine. J Org Chem 2007; 72:2174-81. [PMID: 17291048 DOI: 10.1021/jo0624905] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Quantum mechanical calculations at the B3LYP/6-31+G(d,p) level have been used to investigate the intrinsic conformational preferences of alpha,alpha-diphenylglycine, a simple alpha,alpha-dialkylated amino acid bearing two phenyl substituents on the alpha-carbon, in both the gas phase and aqueous solution. Nine minimum energy conformations have been characterized for the N-acetyl-N'-methylamide derivative within a relative energy range of about 9 kcal/mol. The relative stability of these structures is largely influenced by specific backbone...side chain and side chain...side chain interactions that can be attractive (N-H...pi and C-H...pi) or repulsive (C=O...pi). On the other hand, comparison with the minimum energy conformations calculated for alpha-aminoisobutyric acid, in which the two phenyl substituents are replaced by methyl groups, revealed that the bulky aromatic rings of alpha,alpha-diphenylglycine induce strain in the internal geometry of the peptide. Finally, a set of force-field parameters for classical Molecular Mechanics calculations was developed for the investigated amino acid. Molecular Dynamics simulations in aqueous solutions have been carried out to validate the parameters obtained.
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Affiliation(s)
- Jordi Casanovas
- Departament de Química, Escola Politècnica Superior, Universitat de Lleida, Spain.
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108
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109
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Verdié P, Subra G, Feliu L, Sanchez P, Bergé G, Garcin G, Martinez J. On-Line Synthesis of Pseudopeptide Library Incorporating a Benzodiazepinone Turn Mimic: Biological Evaluation on MC1 Receptors. ACTA ACUST UNITED AC 2006; 9:254-62. [PMID: 17348731 DOI: 10.1021/cc060054q] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Alpha melanocyte stimulating hormone (alpha-MSH) is a widely distributed hormone. This tridecapeptide exhibits various biological activities mediated through different receptors. alpha-MSH binds to the melanocortin-1 receptor (MC1-R), mainly expressed in keratinocytes and melanocytes, inducing melanogenesis and anti-inflammatory processes. The central His-Phe-Arg-Trp tetrapeptide sequence of alpha-MSH is known to form a turn in the bioactive conformation. To find new potent analogs of alpha-MSH, we decided to introduce non-peptide building blocks in the alpha-MSH sequence. Molecular modeling studies showed that two amino acids of the central core sequence could be replaced by the benzodiazepinone building block without loosing the beta-turn conformation. Benzodiazepines are well-known pharmacophores exhibiting a wide scope of biological activities and are described as constrained dipeptide mimics templates. Although numerous synthetic pathways leading to benzodiazepinones have been described in literature, no methodology has 1,4-benzodiazepine-2,5-diones building blocks bearing a free carboxylic acid function and a protected amino function suitable for incorporation into peptide sequences. In this study, we report the synthesis of peptides with a benzodiazepinone moiety obtained directly during the course of solid-phase peptide synthesis (SPPS). This "on-line" strategy leads to the generation of a 54-member pseudo-peptide library of alpha-MSH analogs. After LC/MS purification, binding assays were performed on the MC1 receptor leading to the discovery of several micromolar ligands.
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Affiliation(s)
- Pascal Verdié
- Laboratoire des Aminoacides, Peptides et Protéines (LAPP), UMR 5810, Faculté de Pharmacie, Université de Montpellier I et II, 15 avenue Charles Flahault, 34060 Montpellier, France
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110
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Monroc S, Badosa E, Besalú E, Planas M, Bardají E, Montesinos E, Feliu L. Improvement of cyclic decapeptides against plant pathogenic bacteria using a combinatorial chemistry approach. Peptides 2006; 27:2575-84. [PMID: 16762457 DOI: 10.1016/j.peptides.2006.05.001] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/30/2006] [Revised: 05/02/2006] [Accepted: 05/02/2006] [Indexed: 10/24/2022]
Abstract
Cyclic decapeptides were developed based on the previously reported peptide c(LysLeuLysLeuLysPheLysLeuLysGln). These compounds were active against the economically important plant pathogenic bacteria Erwinia amylovora, Pseudomonas syringae and Xanthomonas vesicatoria. A library of 56 cyclic decapeptides was prepared and screened for antibacterial activity and eukaryotic cytotoxicity, and led to the identification of peptides with improved minimum inhibitory concentration (MIC) against P. syringae (3.1-6.2 microM) and X. vesicatoria (1.6-3.1 microM). Notably, peptides active against E. amylovora (MIC of 12.5-25 microM) were found, constituting the first report of cyclic peptides with activity towards this bacteria. A second library based on the structure c(X(1)X(2)X(3)X(4)LysPheLysLysLeuGln) with X being Lys or Leu yielded peptides with optimized activity profiles. The activity against E. amylovora was further improved (MIC of 6.2-12.5 microM) and the best peptides displayed a low eukaryotic cytotoxicity at concentrations 30-120 times higher than the MIC values. A design of experiments permitted to define rules for high antibacterial activity and low cytotoxicity, being the main rule X(2) not equal X(3), and the secondary rule X(4)=Lys. The best analogs can be considered as good candidates for the development of effective antibacterial agents for use in plant protection.
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Affiliation(s)
- Sylvie Monroc
- Laboratori d'Innovació en Processos i Productes de Síntesi Orgànica (LIPPSO), Departament de Química, Universitat de Girona, Campus Montilivi, 17071 Girona, Spain
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111
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Monroc S, Badosa E, Feliu L, Planas M, Montesinos E, Bardají E. De novo designed cyclic cationic peptides as inhibitors of plant pathogenic bacteria. Peptides 2006; 27:2567-74. [PMID: 16730857 DOI: 10.1016/j.peptides.2006.04.019] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/27/2006] [Revised: 04/18/2006] [Accepted: 04/19/2006] [Indexed: 11/24/2022]
Abstract
Head-to-tail cyclic peptides of 4-10 residues consisting of alternating hydrophilic (Lys) and hydrophobic (Leu and Phe) amino acids were synthesized and tested against the economically important plant pathogenic bacteria Erwinia amylovora, Xanthomonas vesicatoria and Pseudomonas syringae. The antibacterial activity, evaluated as the minimal inhibitory concentration (MIC), the cytotoxicity against human red blood cells and stability towards protease degradation were determined. The influence of cyclization, ring size, and replacement of l-Phe with d-Phe on antibacterial and hemolytic activities was studied and correlated with the degree of structuring and hydrophobicity. Our results showed that linear peptides were inactive against the three bacteria tested. Cyclic peptides were active only toward X. vesicatoria and P. syringae, being c(KLKLKFKLKQ) (BPC10L) the most active peptide with MIC values of 6.25 and 12.5 microM, respectively. The improved antibacterial activity of cyclic peptides compared to their linear counterparts was associated to an increase of the hydrophobicity, represented as RP-HPLC retention time (t(R)), and secondary structure content which are related to an enhanced amphipathicity. A decrease of antibacterial and hemolytic activities was observed when a d-Phe was introduced into the cyclic sequences, which was attributed to their low amphipathicity as shown by their low secondary structure content and low t(R). The small size, simple structure, bactericidal effect, and stability to protease degradation of the best peptides make them potential candidates for the development of effective antibacterial agents for use in plant protection.
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Affiliation(s)
- Sylvie Monroc
- Laboratori d'Innovació en Processos i Productes de Síntesi Orgànica (LIPPSO), Departament de Química, Universitat de Girona, Campus Montilivi, 17071 Girona, Spain
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112
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113
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Synthesis of enantiomerically pure β,β-diphenylalanine (Dip) and fluorenylglycine (Flg). ACTA ACUST UNITED AC 2006. [DOI: 10.1016/j.tetasy.2006.08.007] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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114
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Bull SD, Davies SG, Epstein SW, Garner AC, Mujtaba N, Roberts PM, Savory ED, Smith AD, Tamayo JA, Watkin DJ. Enantiodiscrimination of racemic electrophiles by diketopiperazine enolates: asymmetric synthesis of methyl 2-amino-3-aryl-butanoates and 3-methyl-aspartates. Tetrahedron 2006. [DOI: 10.1016/j.tet.2006.05.033] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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115
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Mollica A, Davis P, Ma SW, Porreca F, Lai J, Hruby VJ. Synthesis and biological activity of the first cyclic biphalin analogues. Bioorg Med Chem Lett 2006; 16:367-72. [PMID: 16275086 DOI: 10.1016/j.bmcl.2005.09.080] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2005] [Revised: 09/23/2005] [Accepted: 09/28/2005] [Indexed: 10/25/2022]
Abstract
Biphalin is a linear octapeptide with strong opioid activity. Its structure is based on two identical sequences derived from enkephalins joined C-terminal to C-terminal by an hydrazide bridge (Tyr-D-Ala-Gly-Phe-NH-NH<--Phe<--Gly<--D-Ala<--Tyr). In this study we present the design, synthesis, and biological evaluation of the first cyclic biphalin analogues. d-Alanine residues in positions 2, 2' of the parent peptide were replaced by d- and l-cysteine and an intramolecular disulfide bond between the cysteine thiol groups was introduced. We obtained two cyclic analogues with quite different biological profiles.
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Affiliation(s)
- Adriano Mollica
- Department of Chemistry, University of Arizona, Tucson, AZ 85721, USA
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116
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Lasa M, López P, Cativiela C. Synthesis of the four stereoisomers of cyclobutane analogues of phenylalanine in enantiomerically pure form. ACTA ACUST UNITED AC 2005. [DOI: 10.1016/j.tetasy.2005.10.015] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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117
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Cativiela C, Lasa M, López P. Synthesis of enantiomerically pure cis- and trans-cyclopentane analogues of phenylalanine. ACTA ACUST UNITED AC 2005. [DOI: 10.1016/j.tetasy.2005.06.017] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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118
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Thomas KM, Naduthambi D, Tririya G, Zondlo NJ. Proline Editing: A Divergent Strategy for the Synthesis of Conformationally Diverse Peptides. Org Lett 2005; 7:2397-400. [PMID: 15932207 DOI: 10.1021/ol0506720] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
[reaction: see text] Strong conformational biases in peptides and proteins can be achieved with 4-substituted proline residues (cis-, trans-, or disubstituted fluoroproline or hydroxyproline). The practical, divergent synthesis of peptides containing these residues, via postsynthetic modification of a peptide containing an internal trans-hydroxyproline residue, is described. Significant differences in the conformations of the peptides Ac-TYXN-NH2 were observed, including K(trans/cis) values, which varied from 1.5 (X = cis-fluoroproline) to 7.0 (X = trans-fluoroproline).
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Affiliation(s)
- Krista M Thomas
- Department of Chemistry and Biochemistry, University of Delaware, Newark, Delaware 19716, USA
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