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Angera IJ, Wright MM, Del Valle JR. Beyond N-Alkylation: Synthesis, Structure, and Function of N-Amino Peptides. Acc Chem Res 2024; 57:1287-1297. [PMID: 38626119 DOI: 10.1021/acs.accounts.4c00024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/18/2024]
Abstract
The growing list of physiologically important protein-protein interactions (PPIs) has amplified the need for compounds to target topologically complex biomolecular surfaces. In contrast to small molecules, peptide and protein mimics can exhibit three-dimensional shape complementarity across a large area and thus have the potential to significantly expand the "druggable" proteome. Strategies to stabilize canonical protein secondary structures without sacrificing side-chain content are particularly useful in the design of peptide-based chemical probes and therapeutics.Substitution of the backbone amide in peptides represents a subtle chemical modification with profound effects on conformation and stability. Studies focused on N-alkylation have already led to broad-ranging applications in peptidomimetic design. Inspired by nonribosomal peptide natural products harboring amide N-oxidations, we envisioned that main-chain hydrazide and hydroxamate bonds would impose distinct conformational preferences and offer unique opportunities for backbone diversification. This Account describes our exploration of peptide N-amination as a strategy for stabilizing canonical protein folds and for the structure-based design of soluble amyloid mimics.We developed a general synthetic protocol to access N-amino peptides (NAPs) on solid support. In an effort to stabilize β-strand conformation, we designed stitched peptidomimetics featuring covalent tethering of the backbone N-amino substituent to the preceding residue side chain. Using a combination of NMR, X-ray crystallography, and molecular dynamics simulations, we discovered that backbone N-amination alone could significantly stabilize β-hairpin conformation in multiple models of folding. Our studies revealed that the amide NH2 substituent in NAPs participates in cooperative noncovalent interactions that promote β-sheet secondary structure. In contrast to Cα-substituted α-hydrazino acids, we found that N-aminoglycine and its N'-alkylated derivatives instead stabilize polyproline II (PPII) conformation. The reactivity of hydrazides also allows for late-stage peptide macrocyclization, affording novel covalent surrogates of side-chain-backbone H-bonds.The pronounced β-sheet propensity of Cα-substituted α-hydrazino acids prompted us to target amyloidogenic proteins using NAP-based β-strand mimics. Backbone N-amination was found to render aggregation-prone lead sequences soluble and resistant to proteolysis. Inhibitors of Aβ and tau identified through N-amino scanning blocked protein aggregation and the formation of mature fibrils in vitro. We further identified NAP-based single-strand and cross-β tau mimics capable of inhibiting the prion-like cellular seeding activity of recombinant and patient-derived tau fibrils.Our studies establish backbone N-amination as a valuable addition to the peptido- and proteomimetic tool kit. α-Hydrazino acids show particular promise as minimalist β-strand mimics that retain side-chain information. Late-stage derivatization of hydrazides also provides facile entry into libraries of backbone-edited peptides. We anticipate that NAPs will thus find applications in the development of optimally constrained folds and modulators of PPIs.
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Affiliation(s)
- Isaac J Angera
- Department of Chemistry & Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, United States
| | - Madison M Wright
- Department of Chemistry & Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, United States
| | - Juan R Del Valle
- Department of Chemistry & Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, United States
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2
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Synthetic and computational efforts towards the development of peptidomimetics and small-molecule SARS-CoV 3CLpro inhibitors. Bioorg Med Chem 2021; 46:116301. [PMID: 34332853 PMCID: PMC8254399 DOI: 10.1016/j.bmc.2021.116301] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2021] [Revised: 06/25/2021] [Accepted: 06/27/2021] [Indexed: 12/24/2022]
Abstract
Severe Acute Respiratory Syndrome (SARS) is a severe febrile respiratory disease caused by the beta genus of human coronavirus, known as SARS-CoV. Last year, 2019-n-CoV (COVID-19) was a global threat for everyone caused by the outbreak of SARS-CoV-2. 3CLpro, chymotrypsin-like protease, is a major cysteine protease that substantially contributes throughout the viral life cycle of SARS-CoV and SARS-CoV-2. It is a prospective target for the development of SARS-CoV inhibitors by applying a repurposing strategy. This review focuses on a detailed overview of the chemical synthesis and computational chemistry perspectives of peptidomimetic inhibitors (PIs) and small-molecule inhibitors (SMIs) targeting viral proteinase discovered from 2004 to 2020. The PIs and SMIs are one of the primary therapeutic inventions for SARS-CoV. The journey of different analogues towards the evolution of SARS-CoV 3CLpro inhibitors and complete synthetic preparation of nineteen derivatives of PIs and ten derivatives of SMIs and their computational chemistry perspectives were reviewed. From each class of derivatives, we have identified and highlighted the most compelling PIs and SMIs for SARS-CoV 3CLpro. The protein-ligand interaction of 29 inhibitors were also studied that involved with the 3CLpro inhibition, and the frequent amino acid residues of the protease were also analyzed that are responsible for the interactions with the inhibitors. This work will provide an initiative to encourage further research for the development of effective and drug-like 3CLpro inhibitors against coronaviruses in the near future.
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3
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Vu QN, Young R, Sudhakar HK, Gao T, Huang T, Tan YS, Lau YH. Cyclisation strategies for stabilising peptides with irregular conformations. RSC Med Chem 2021; 12:887-901. [PMID: 34263169 PMCID: PMC8230030 DOI: 10.1039/d1md00098e] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2021] [Accepted: 04/12/2021] [Indexed: 11/21/2022] Open
Abstract
Cyclisation is a common synthetic strategy for enhancing the therapeutic potential of peptide-based molecules. While there are extensive studies on peptide cyclisation for reinforcing regular secondary structures such as α-helices and β-sheets, there are remarkably few reports of cyclising peptides which adopt irregular conformations in their bioactive target-bound state. In this review, we highlight examples where cyclisation techniques have been successful in stabilising irregular conformations, then discuss how the design of cyclic constraints for irregularly structured peptides can be informed by existing β-strand stabilisation approaches, new computational design techniques, and structural principles extracted from cyclic peptide library screening hits. Through this analysis, we demonstrate how existing peptide cyclisation techniques can be adapted to address the synthetic design challenge of stabilising irregularly structured binding motifs.
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Affiliation(s)
- Quynh Ngoc Vu
- School of Chemistry, Eastern Ave, The University of Sydney NSW 2006 Australia
| | - Reginald Young
- School of Chemistry, Eastern Ave, The University of Sydney NSW 2006 Australia
| | | | - Tianyi Gao
- School of Chemistry, Eastern Ave, The University of Sydney NSW 2006 Australia
| | - Tiancheng Huang
- School of Chemistry, Eastern Ave, The University of Sydney NSW 2006 Australia
| | - Yaw Sing Tan
- Bioinformatics Institute, Agency for Science, Technology and Research (ASTAR) 30 Biopolis Street, #07-01, Matrix Singapore 138671 Singapore
| | - Yu Heng Lau
- School of Chemistry, Eastern Ave, The University of Sydney NSW 2006 Australia
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4
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Staśkiewicz A, Ledwoń P, Rovero P, Papini AM, Latajka R. Triazole-Modified Peptidomimetics: An Opportunity for Drug Discovery and Development. Front Chem 2021; 9:674705. [PMID: 34095086 PMCID: PMC8172596 DOI: 10.3389/fchem.2021.674705] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2021] [Accepted: 04/06/2021] [Indexed: 12/18/2022] Open
Abstract
Peptidomimetics play a fundamental role in drug design due to their preferential properties regarding natural peptides. In particular, compounds possessing nitrogen-containing heterocycles have been intensively studied in recent years. The triazolyl moiety incorporation decreases the molecule susceptibility to enzymatic degradation, reduction, hydrolysis, and oxidation. In fact, peptides containing triazole rings are a typical example of peptidomimetics. They have all the advantages over classic peptides. Both efficient synthetic methods and biological activity make these systems an interesting and promising object of research. Peptide triazole derivatives display a diversity of biological properties and can be obtained via numerous synthetic strategies. In this review, we have highlighted the importance of the triazole-modified peptidomimetics in the field of drug design. We present an overview on new achievements in triazolyl-containing peptidomimetics synthesis and their biological activity as inhibitors of enzymes or against cancer, viruses, bacteria, or fungi. The relevance of above-mentioned compounds was confirmed by their comparison with unmodified peptides.
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Affiliation(s)
- Agnieszka Staśkiewicz
- Department of Bioorganic Chemistry, Faculty of Chemistry, Wroclaw University of Science and Technology, Wroclaw, Poland
- Interdepartmental Research Unit of Peptide and Protein Chemistry and Biology, Department of Chemistry “Ugo Schiff”, University of Florence, Firenze, Italy
| | - Patrycja Ledwoń
- Department of Bioorganic Chemistry, Faculty of Chemistry, Wroclaw University of Science and Technology, Wroclaw, Poland
- Interdepartmental Research Unit of Peptide and Protein Chemistry and Biology, Department of Neurosciences, Psychology, Drug Research and Child Health-Section of Pharmaceutical Sciences and Nutraceutics, University of Florence, Firenze, Italy
| | - Paolo Rovero
- Interdepartmental Research Unit of Peptide and Protein Chemistry and Biology, Department of Neurosciences, Psychology, Drug Research and Child Health-Section of Pharmaceutical Sciences and Nutraceutics, University of Florence, Firenze, Italy
| | - Anna Maria Papini
- Interdepartmental Research Unit of Peptide and Protein Chemistry and Biology, Department of Chemistry “Ugo Schiff”, University of Florence, Firenze, Italy
| | - Rafal Latajka
- Department of Bioorganic Chemistry, Faculty of Chemistry, Wroclaw University of Science and Technology, Wroclaw, Poland
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5
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Donkor IO. An update on the therapeutic potential of calpain inhibitors: a patent review. Expert Opin Ther Pat 2020; 30:659-675. [PMID: 32700591 DOI: 10.1080/13543776.2020.1797678] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
INTRODUCTION Calpain is a cytosolic proteinase that regulates of a wide range of physiological functions. The enzyme has been implicated in various pathological conditions including neurodegenerative disorders, cardiovascular disorders, cancer, and several other diseases. Therefore, calpain inhibitors are of interest as therapeutic agents and have been studied in preclinical models of several diseases in which the enzyme has been implicated. AREAS COVERED Calpain inhibitors that were disclosed over the last 5 years (2015-2019) include calpastatin-based peptidomimetics; thalassospiramide lipopeptides; disulfide analogs of alpha-mercaptoacrylic acids; allosteric modulators; azoloimidazolidenones; and macrocyclic/non-macrocyclic carboxamides. The effectiveness of some of the inhibitors in preclinical animal models is discussed. EXPERT OPINION Significant milestones that were made over this time frame include: a) disclosure of novel blood-brain barrier (BBB) permeable calpastatin analogs as calpain inhibitors; b) disclosure that potent calpain inhibitors can be obtained by targeting the hydrophobic pockets on chain A of PEF(S) of the small subunit of calpain; c) use of PEF(S) (PDB ID: 4WQ2) in virtual screening to identify novel structurally diverse calpain inhibitors; and d) mitigation of the metabolic instability of the alpha-ketoamide warhead of calpain inhibitors.
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Affiliation(s)
- Isaac O Donkor
- Department of Pharmaceutical Sciences, University of Tennessee Health Science Center, College of Pharmacy , Memphis, Tennessee, United States
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6
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Abstract
This Review is devoted to the chemistry of macrocyclic peptides having heterocyclic fragments in their structure. These motifs are present in many natural products and synthetic macrocycles designed against a particular biochemical target. Thiazole and oxazole are particularly common constituents of naturally occurring macrocyclic peptide molecules. This frequency of occurrence is because the thiazole and oxazole rings originate from cysteine, serine, and threonine residues. Whereas other heteroaryl groups are found less frequently, they offer many insightful lessons that range from conformational control to receptor/ligand interactions. Many options to develop new and improved technologies to prepare natural products have appeared in recent years, and the synthetic community has been pursuing synthetic macrocycles that have no precedent in nature. This Review attempts to summarize progress in this area.
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Affiliation(s)
- Ivan V Smolyar
- Department of Chemistry , Moscow State University , Leninskije Gory , 199991 Moscow , Russia
| | - Andrei K Yudin
- Davenport Research Laboratories, Department of Chemistry , University of Toronto , 80 St. George Street , Toronto , Ontario M5S 3H6 , Canada
| | - Valentine G Nenajdenko
- Department of Chemistry , Moscow State University , Leninskije Gory , 199991 Moscow , Russia
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7
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Schumann NC, Bruning J, Marshall AC, Abell AD. The role of N-terminal heterocycles in hydrogen bonding to α-chymotrypsin. Bioorg Med Chem Lett 2019; 29:396-399. [PMID: 30579793 DOI: 10.1016/j.bmcl.2018.12.032] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2018] [Revised: 12/11/2018] [Accepted: 12/14/2018] [Indexed: 01/14/2023]
Abstract
A series of dipeptide aldehydes containing different N-terminal heterocycles was prepared and assayed in vitro against α-chymotrypsin to ascertain the importance of the heterocycle in maintaining a β-strand geometry while also providing a hydrogen bond donor equivalent to the backbone amide nitrogen of the surrogate amino acid. The dipeptide containing a pyrrole constraint (10) was the most potent inhibitor, with >30-fold improved activity over dipeptides which lacked a nitrogen hydrogen bond donor (namely thiophene 11, furan 12 and pyridine 13). Molecular docking studies of 10 bound to α-chymotrypsin demonstrates a hydrogen bond between the pyrrole nitrogen donor and the backbone carbonyl of Gly216 located in the S3 pocket which is proposed to be critical for overall binding.
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Affiliation(s)
- Nicholas C Schumann
- School of Chemistry & Physics, The University of Adelaide, North Terrace, Adelaide, SA 5005, Australia
| | - John Bruning
- School of Biological Sciences, The University of Adelaide, North Terrace, Adelaide, SA 5005, Australia
| | - Andrew C Marshall
- School of Biological Sciences, The University of Adelaide, North Terrace, Adelaide, SA 5005, Australia
| | - Andrew D Abell
- School of Chemistry & Physics, The University of Adelaide, North Terrace, Adelaide, SA 5005, Australia; ARC Centre of Excellence for Nanoscale BioPhotonics (CNBP) and Institute of Photonics and Advanced Sensing (IPAS), The University of Adelaide, Adelaide, South Australia 5005, Australia.
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8
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Tripeptide analogues of MG132 as protease inhibitors. Bioorg Med Chem 2018; 27:436-441. [PMID: 30581047 DOI: 10.1016/j.bmc.2018.12.022] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2018] [Revised: 12/12/2018] [Accepted: 12/13/2018] [Indexed: 12/17/2022]
Abstract
The 26S proteasome and calpain are linked to a number of important human diseases. Here, we report a series of analogues of the prototypical tripeptide aldehyde inhibitor MG132 that show a unique combination of high activity and selectivity for calpains over proteasome. Tripeptide aldehydes (1-3) with an aromatic P3 substituent show enhanced activity and selectivity against ovine calpain 2 relative to chymotrypsin-like activity of proteasome. Docking studies reveal the key contacts between inhibitors and calpain to confirm the importance of the S3 pocket with respect to selectivity between calpains 1 and 2 and the proteasome.
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9
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Peptides as Bio-inspired Molecular Electronic Materials. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2017. [PMID: 29081052 DOI: 10.1007/978-3-319-66095-0_6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register]
Abstract
Understanding the electronic properties of single peptides is not only of fundamental importance to biology, but it is also pivotal to the realization of bio-inspired molecular electronic materials. Natural proteins have evolved to promote electron transfer in many crucial biological processes. However, their complex conformational nature inhibits a thorough investigation, so in order to study electron transfer in proteins, simple peptide models containing redox active moieties present as ideal candidates. Here we highlight the importance of secondary structure characteristic to proteins/peptides, and its relevance to electron transfer. The proposed mechanisms responsible for such transfer are discussed, as are details of the electrochemical techniques used to investigate their electronic properties. Several factors that have been shown to influence electron transfer in peptides are also considered. Finally, a comprehensive experimental and theoretical study demonstrates that the electron transfer kinetics of peptides can be successfully fine tuned through manipulation of chemical composition and backbone rigidity. The methods used to characterize the conformation of all peptides synthesized throughout the study are outlined, along with the various approaches used to further constrain the peptides into their geometric conformations. The aforementioned sheds light on the potential of peptides to one day play an important role in the fledgling field of molecular electronics.
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10
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Blanco B, Palasis KA, Adwal A, Callen DF, Abell AD. Azobenzene-containing photoswitchable proteasome inhibitors with selective activity and cellular toxicity. Bioorg Med Chem 2017. [PMID: 28642029 DOI: 10.1016/j.bmc.2017.06.011] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
A series of azobenzene-containing peptidic boronate esters was prepared and the activity of the thermally adapted states (TAS), enriched in trans isomer, and the photostationary states (PSS), enriched in cis isomer, for each compound were evaluated against β5 and β1 proteasome subunits. Compounds with a sterically demanding phenyl-substituted azobenzene at P2 (4c), and a less sterically demanding unsubstituted azobenzene at the N-terminus (5a), showed the greatest difference in activity between the two states. In both cases, the more active trans-enriched TAS had activity comparable to bortezomib and delanzomib. Furthermore, cis-enriched 4c inhibited tumor growth in both breast and colorectal carcinoma cell lines. Significantly, the initial trans-enriched TAS of 4c was not cytotoxic against the non-malignant MCF-10A cells.
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Affiliation(s)
- Beatriz Blanco
- Department of Chemistry, The University of Adelaide, North Terrace, Adelaide, South Australia 5005, Australia
| | - Kathryn A Palasis
- Department of Chemistry, The University of Adelaide, North Terrace, Adelaide, South Australia 5005, Australia; ARC Centre of Excellence for Nanoscale BioPhotonics (CNBP) and Institute of Photonics and Advanced Sensing (IPAS), The University of Adelaide, Adelaide, South Australia 5005, Australia
| | - Alaknanda Adwal
- Centre for Personalised Cancer Medicine, Discipline of Medicine, The University of Adelaide, North Terrace, Adelaide, South Australia 5005, Australia
| | - David F Callen
- Centre for Personalised Cancer Medicine, Discipline of Medicine, The University of Adelaide, North Terrace, Adelaide, South Australia 5005, Australia
| | - Andrew D Abell
- Department of Chemistry, The University of Adelaide, North Terrace, Adelaide, South Australia 5005, Australia; ARC Centre of Excellence for Nanoscale BioPhotonics (CNBP) and Institute of Photonics and Advanced Sensing (IPAS), The University of Adelaide, Adelaide, South Australia 5005, Australia.
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11
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Pícha J, Buděšínský M, Macháčková K, Collinsová M, Jiráček J. Optimized syntheses of Fmoc azido amino acids for the preparation of azidopeptides. J Pept Sci 2017; 23:202-214. [PMID: 28120383 PMCID: PMC5347871 DOI: 10.1002/psc.2968] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2016] [Revised: 12/20/2016] [Accepted: 12/20/2016] [Indexed: 12/17/2022]
Abstract
The rise of CuI‐catalyzed click chemistry has initiated an increased demand for azido and alkyne derivatives of amino acid as precursors for the synthesis of clicked peptides. However, the use of azido and alkyne amino acids in peptide chemistry is complicated by their high cost. For this reason, we investigated the possibility of the in‐house preparation of a set of five Fmoc azido amino acids: β‐azido l‐alanine and d‐alanine, γ‐azido l‐homoalanine, δ‐azido l‐ornithine and ω‐azido l‐lysine. We investigated several reaction pathways described in the literature, suggested several improvements and proposed several alternative routes for the synthesis of these compounds in high purity. Here, we demonstrate that multigram quantities of these Fmoc azido amino acids can be prepared within a week or two and at user‐friendly costs. We also incorporated these azido amino acids into several model tripeptides, and we observed the formation of a new elimination product of the azido moiety upon conditions of prolonged couplings with 2‐(1H‐benzotriazol‐1‐yl)‐1,1,3,3‐tetramethyluronium hexafluorophosphate/DIPEA. We hope that our detailed synthetic protocols will inspire some peptide chemists to prepare these Fmoc azido acids in their laboratories and will assist them in avoiding the too extensive costs of azidopeptide syntheses. Experimental procedures and/or analytical data for compounds 3–5, 20, 25, 26, 30 and 43–47 are provided in the supporting information. © 2017 The Authors Journal of Peptide Science published by European Peptide Society and John Wiley & Sons Ltd.
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Affiliation(s)
- Jan Pícha
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, v.v.i., Flemingovo nám. 2, 166 10, Prague 6, Czech Republic
| | - Miloš Buděšínský
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, v.v.i., Flemingovo nám. 2, 166 10, Prague 6, Czech Republic
| | - Kateřina Macháčková
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, v.v.i., Flemingovo nám. 2, 166 10, Prague 6, Czech Republic
| | - Michaela Collinsová
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, v.v.i., Flemingovo nám. 2, 166 10, Prague 6, Czech Republic
| | - Jiří Jiráček
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, v.v.i., Flemingovo nám. 2, 166 10, Prague 6, Czech Republic
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12
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Yu J, Horsley JR, Abell AD. Turning electron transfer ‘on-off’ in peptides through side-bridge gating. Electrochim Acta 2016. [DOI: 10.1016/j.electacta.2016.05.067] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
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13
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Weerawarna PM, Kim Y, Galasiti Kankanamalage AC, Damalanka VC, Lushington GH, Alliston KR, Mehzabeen N, Battaile KP, Lovell S, Chang KO, Groutas WC. Structure-based design and synthesis of triazole-based macrocyclic inhibitors of norovirus protease: Structural, biochemical, spectroscopic, and antiviral studies. Eur J Med Chem 2016; 119:300-18. [PMID: 27235842 PMCID: PMC4916972 DOI: 10.1016/j.ejmech.2016.04.013] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2016] [Revised: 04/04/2016] [Accepted: 04/06/2016] [Indexed: 01/14/2023]
Abstract
Outbreaks of acute gastroenteritis caused by noroviruses constitute a public health concern worldwide. To date, there are no approved drugs or vaccines for the management and prophylaxis of norovirus infections. A potentially effective strategy for the development of norovirus therapeutics entails the discovery of inhibitors of norovirus 3CL protease, an enzyme essential for noroviral replication. We describe herein the structure-based design of the first class of permeable, triazole-based macrocyclic inhibitors of norovirus 3C-like protease, as well as pertinent X-ray crystallographic, biochemical, spectroscopic, and antiviral studies. Novel triazole-based macrocyclic inhibitors of norovirus 3CL protease were synthesized. The interplay of conformation and activity was probed using NMR and X-ray crystallography. Bound inhibitors assume a β-strand conformation according to X-ray crystal structure. Loss of critical hydrogen bonding interactions was revealed by X-ray crystallography.
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Affiliation(s)
| | - Yunjeong Kim
- Department of Diagnostic Medicine & Pathobiology, College of Veterinary Medicine, Kansas State University, Manhattan, KS 66506, USA
| | | | - Vishnu C Damalanka
- Department of Chemistry, Wichita State University, Wichita, KS 67260, USA
| | | | - Kevin R Alliston
- Department of Chemistry, Wichita State University, Wichita, KS 67260, USA
| | - Nurjahan Mehzabeen
- Protein Structure Laboratory, The University of Kansas, Lawrence, KS 66047, USA
| | - Kevin P Battaile
- IMCA-CAT, Hauptman-Woodward Medical Research Institute, APS Argonne National Laboratory, Argonne, IL 60439, USA
| | - Scott Lovell
- Protein Structure Laboratory, The University of Kansas, Lawrence, KS 66047, USA
| | - Kyeong-Ok Chang
- Department of Diagnostic Medicine & Pathobiology, College of Veterinary Medicine, Kansas State University, Manhattan, KS 66506, USA.
| | - William C Groutas
- Department of Chemistry, Wichita State University, Wichita, KS 67260, USA.
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14
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Zhang X, Bruning JB, George JH, Abell AD. A mechanistic study on the inhibition of α-chymotrypsin by a macrocyclic peptidomimetic aldehyde. Org Biomol Chem 2016; 14:6970-8. [DOI: 10.1039/c6ob01159d] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
NMR and X-ray crystallography reveals covalent attachment of the macrocyclic aldehyde to serine195 of α-chymotrypsin and that its backbone binds as a β-strand.
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Affiliation(s)
- X. Zhang
- ARC Centre of Excellence for Nanoscale BioPhotonics (CNBP)
- Institute for Photonics and Advanced Sensing
- Department of Chemistry
- The University of Adelaide
- Adelaide
| | - J. B. Bruning
- School of Biological Sciences
- The University of Adelaide
- Adelaide
- Australia
| | - J. H. George
- Department of Chemistry
- The University of Adelaide
- Adelaide
- Australia
| | - A. D. Abell
- ARC Centre of Excellence for Nanoscale BioPhotonics (CNBP)
- Institute for Photonics and Advanced Sensing
- Department of Chemistry
- The University of Adelaide
- Adelaide
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15
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Coffey SB, Aspnes G, Londregan AT. Expedient Synthesis of N1-Substituted Triazole Peptidomimetics. ACS COMBINATORIAL SCIENCE 2015; 17:706-9. [PMID: 26562078 DOI: 10.1021/acscombsci.5b00150] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
A general procedure for the rapid diversification of peptide scaffolds is described. A one-pot click reaction between a peptide-alkyne and a series of in situ generated aryl/alkyl azides affords novel N1-substituted triazole peptidomimetics. This transformation is of broad scope, operates under mild conditions, and is parallel chemical synthesis compatible.
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Affiliation(s)
- Steven B. Coffey
- Pfizer Worldwide Medicinal Chemistry, Eastern Point Road, Groton, Connecticut 06340, United States
| | - Gary Aspnes
- Pfizer Worldwide Medicinal Chemistry, Eastern Point Road, Groton, Connecticut 06340, United States
- Pfizer Worldwide Medicinal Chemistry, 610 Main Street, Cambridge, Massachusetts 02139, United States
| | - Allyn T. Londregan
- Pfizer Worldwide Medicinal Chemistry, Eastern Point Road, Groton, Connecticut 06340, United States
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16
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Horsley JR, Yu J, Abell AD. The Correlation of Electrochemical Measurements and Molecular Junction Conductance Simulations in β-Strand Peptides. Chemistry 2015; 21:5926-33. [DOI: 10.1002/chem.201406451] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2014] [Indexed: 01/14/2023]
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17
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Abstract
INTRODUCTION Calpain is a family of cysteine proteases found in eukaryotes and a few bacteria. There is considerable interest in the search for calpain inhibitors because the enzyme has been implicated in several diseases including ocular disorders, neurodegenerative disorders, metabolic disorders and cancer. AREAS COVERED An overview of calpain inhibitors disclosed between 2012 and 2014 is presented. Among these are epoxysuccinates, dipeptide imaging agents, macrocyclic inhibitors, α-helical peptidomimetic inhibitors, carboxamides, 5-azolones and α-mercaptoacrylates. Additionally, preclinical studies of calpain inhibitors in pathologies such blood disorders, ocular disorders, neurological disorders and muscle disorders are discussed. EXPERT OPINION Major advances made in calpain inhibitor research between 2012 and 2014 include: i) the discovery of cytosolic-stable carboxamide calpain inhibitors; ii) synthesis of epoxysuccinates with excellent bioavailability; iii) disclosure of the X-ray crystal structures of novel α-mercaptoacrylates bound to the pentaEF hand region from human calpain; and iv) disclosure of calpain inhibitors as anti-sickling agents. Several calpain inhibitors were reported but limited effort was directed towards the discovery of calpain isoform selective agents, which continues to dampen the therapeutic potential of calpain inhibitors.
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Affiliation(s)
- Isaac O Donkor
- The University of Tennessee Health Science Center , Memphis, TN , USA
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18
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Horsley JR, Yu J, Moore KE, Shapter JG, Abell AD. Unraveling the interplay of backbone rigidity and electron rich side-chains on electron transfer in peptides: the realization of tunable molecular wires. J Am Chem Soc 2014; 136:12479-88. [PMID: 25122122 PMCID: PMC4156867 DOI: 10.1021/ja507175b] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2014] [Indexed: 01/14/2023]
Abstract
Electrochemical studies are reported on a series of peptides constrained into either a 310-helix (1-6) or β-strand (7-9) conformation, with variable numbers of electron rich alkene containing side chains. Peptides (1 and 2) and (7 and 8) are further constrained into these geometries with a suitable side chain tether introduced by ring closing metathesis (RCM). Peptides 1, 4 and 5, each containing a single alkene side chain reveal a direct link between backbone rigidity and electron transfer, in isolation from any effects due to the electronic properties of the electron rich side-chains. Further studies on the linear peptides 3-6 confirm the ability of the alkene to facilitate electron transfer through the peptide. A comparison of the electrochemical data for the unsaturated tethered peptides (1 and 7) and saturated tethered peptides (2 and 8) reveals an interplay between backbone rigidity and effects arising from the electron rich alkene side-chains on electron transfer. Theoretical calculations on β-strand models analogous to 7, 8 and 9 provide further insights into the relative roles of backbone rigidity and electron rich side-chains on intramolecular electron transfer. Furthermore, electron population analysis confirms the role of the alkene as a "stepping stone" for electron transfer. These findings provide a new approach for fine-tuning the electronic properties of peptides by controlling backbone rigidity, and through the inclusion of electron rich side-chains. This allows for manipulation of energy barriers and hence conductance in peptides, a crucial step in the design and fabrication of molecular-based electronic devices.
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Affiliation(s)
- John R. Horsley
- ARC
Centre of Excellence for Nanoscale BioPhotonics (CNBP), School of
Chemistry and Physics, The University of
Adelaide, Adelaide, South Australia 5005, Australia
| | - Jingxian Yu
- ARC
Centre of Excellence for Nanoscale BioPhotonics (CNBP), School of
Chemistry and Physics, The University of
Adelaide, Adelaide, South Australia 5005, Australia
| | - Katherine E. Moore
- Centre
for Nanoscale Science and Technology, School of Chemical & Physical
Science, Flinders University, Bedford Park, South Australia 5042, Australia
| | - Joe G. Shapter
- Centre
for Nanoscale Science and Technology, School of Chemical & Physical
Science, Flinders University, Bedford Park, South Australia 5042, Australia
| | - Andrew D. Abell
- ARC
Centre of Excellence for Nanoscale BioPhotonics (CNBP), School of
Chemistry and Physics, The University of
Adelaide, Adelaide, South Australia 5005, Australia
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19
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20
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Chua KCH, Pietsch M, Zhang X, Hautmann S, Chan HY, Bruning JB, Gütschow M, Abell AD. Macrocyclic Protease Inhibitors with Reduced Peptide Character. Angew Chem Int Ed Engl 2014; 53:7828-31. [DOI: 10.1002/anie.201404301] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2014] [Indexed: 01/14/2023]
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21
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Jones SA, Neilsen PM, Siew L, Callen DF, Goldfarb NE, Dunn BM, Abell AD. A template-based approach to inhibitors of calpain 2, 20S proteasome, and HIV-1 protease. ChemMedChem 2013; 8:1918-21. [PMID: 24130198 DOI: 10.1002/cmdc.201300387] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2013] [Revised: 10/07/2013] [Indexed: 01/14/2023]
Abstract
Specificity counts: A template-based approach to protease inhibitors is presented using a core macrocycle that presents a generic β-strand template for binding to protease active sites. This is then specifically functionalized at P2 , and the C and N termini to give inhibitors of calpain 2, 20S proteasome, and HIV-1 protease.
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Affiliation(s)
- Seth A Jones
- School Chemistry and Physics, The University of Adelaide, Adelaide, SA 5005 (Australia)
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22
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Template-constrained macrocyclic peptides prepared from native, unprotected precursors. Proc Natl Acad Sci U S A 2013; 110:E3753-60. [PMID: 24043790 DOI: 10.1073/pnas.1311706110] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Peptide-protein interactions are important mediators of cellular-signaling events. Consensus binding motifs (also known as short linear motifs) within these contacts underpin molecular recognition, yet have poor pharmacological properties as discrete species. Here, we present methods to transform intact peptides into stable, templated macrocycles. Two simple steps install the template. The key reaction is a palladium-catalyzed macrocyclization. The catalysis has broad scope and efficiently forms large rings by engaging native peptide functionality including phenols, imidazoles, amines, and carboxylic acids without the necessity of protecting groups. The tunable reactivity of the template gives the process special utility. Defined changes in reaction conditions markedly alter chemoselectivity. In all cases examined, cyclization occurs rapidly and in high yield at room temperature, regardless of peptide composition or chain length. We show that conformational restraints imparted by the template stabilize secondary structure and enhance proteolytic stability in vitro. Palladium-catalyzed internal cinnamylation is a strong complement to existing methods for peptide modification.
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23
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Lawson KV, Rose TE, Harran PG. Template-induced macrocycle diversity through large ring-forming alkylations of tryptophan. Tetrahedron 2013; 69:7683-7691. [PMID: 23976797 DOI: 10.1016/j.tet.2013.05.060] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Macrocyclic peptidomimetics are valuable in research and serve as lead compounds in drug discovery efforts. New methods to prepare such structures are of considerable interest. In this pilot study, we show that an organic template harboring a latent cinnamyl cation participates in novel Friedel-Crafts macrocyclization reactions with tryptophan. Upon joining the template to Trp-Trp-Tyr, a single operation efficiently generates eight unique macrocycles. Each has been isolated and thoroughly characterized. Product distribution as a function of Brønsted and/or Lewis acidic conditions was explored, and outcomes were compared to rearrangements induced within a corresponding tyrosine-linked cyclic ether. The solution structure of a new macrocyclic pyrroloindoline was solved using a combination of two-dimensional NMR methods and molecular mechanics simulations. Template-induced structural diversification of peptide sequences harboring aromatic residues has potential to create myriad macrocycles that target surfaces involved in protein-protein interactions.
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Affiliation(s)
- Kenneth V Lawson
- Department of Chemistry and Biochemistry, University of California Los Angeles, 607 Charles E. Young Drive East, Los Angeles, CA 90095-1569 (USA)
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24
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Mandadapu SR, Weerawarna PM, Prior AM, Uy RAZ, Aravapalli S, Alliston KR, Lushington GH, Kim Y, Hua DH, Chang KO, Groutas WC. Macrocyclic inhibitors of 3C and 3C-like proteases of picornavirus, norovirus, and coronavirus. Bioorg Med Chem Lett 2013; 23:3709-12. [PMID: 23727045 PMCID: PMC3750990 DOI: 10.1016/j.bmcl.2013.05.021] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2013] [Revised: 04/29/2013] [Accepted: 05/07/2013] [Indexed: 12/18/2022]
Abstract
The design, synthesis, and in vitro evaluation of the first macrocyclic inhibitor of 3C and 3C-like proteases of picornavirus, norovirus, and coronavirus are reported. The in vitro inhibitory activity (50% effective concentration) of the macrocyclic inhibitor toward enterovirus 3C protease (CVB3 Nancy strain), and coronavirus (SARS-CoV) and norovirus 3C-like proteases, was determined to be 1.8, 15.5 and 5.1 μM, respectively.
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Affiliation(s)
| | | | - Allan M. Prior
- Department of Chemistry, Kansas State University, Manhattan, KS 66506, USA
| | | | - Sridhar Aravapalli
- Department of Chemistry, Wichita State University, Wichita, KS 67260, USA
| | - Kevin R. Alliston
- Department of Chemistry, Wichita State University, Wichita, KS 67260, USA
| | | | - Yunjeong Kim
- Department of Diagnostic Medicine/Pathobiology, College of Veterinary Medicine, Kansas State University, Manhattan, KS 66506, USA
| | - Duy H. Hua
- Department of Chemistry, Kansas State University, Manhattan, KS 66506, USA
| | - Kyeong-Ok Chang
- Department of Diagnostic Medicine/Pathobiology, College of Veterinary Medicine, Kansas State University, Manhattan, KS 66506, USA
| | - William C. Groutas
- Department of Chemistry, Wichita State University, Wichita, KS 67260, USA
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25
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Chen H, Jiao W, Jones MA, Coxon JM, Morton JD, Bickerstaffe R, Pehere AD, Zvarec O, Abell AD. New tripeptide-based macrocyclic calpain inhibitors formed by N-alkylation of histidine. Chem Biodivers 2013; 9:2473-84. [PMID: 23161629 DOI: 10.1002/cbdv.201200320] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2012] [Indexed: 01/14/2023]
Abstract
Two new series of 15-membered macrocyclic peptidomimetics, in which the P1 and P3 residues of the peptide backbone are linked by a bridge containing a 1,4-disubstituted 1H-imidazole, are reported. The structure with an aldehyde at the C-terminus and the imidazole at P3, i.e., 4c, shows significant inhibitory activity against calpain 2, with an IC(50) value of 238 nM. The macrocyclic aldehyde with the imidazole at the alternative P1 position, i.e., 5c, is significantly less active. The relative activities are linked to the ability of the component macrocycles to mimic a β-strand geometry that is known to favor active-site binding. This ability is defined by conformational searches and docking studies with calpain.
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Affiliation(s)
- Hongyuan Chen
- Chemistry Department, University of Canterbury, Christchurch, New Zealand
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26
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Pehere AD, Pietsch M, Gütschow M, Neilsen PM, Pedersen DS, Nguyen S, Zvarec O, Sykes MJ, Callen DF, Abell AD. Synthesis and extended activity of triazole-containing macrocyclic protease inhibitors. Chemistry 2013; 19:7975-81. [PMID: 23606616 DOI: 10.1002/chem.201204260] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2012] [Revised: 03/12/2013] [Indexed: 12/26/2022]
Abstract
Peptide-derived protease inhibitors are an important class of compounds with the potential to treat a wide range of diseases. Herein, we describe the synthesis of a series of triazole-containing macrocyclic protease inhibitors pre-organized into a β-strand conformation and an evaluation of their activity against a panel of proteases. Acyclic azido-alkyne-based aldehydes are also evaluated for comparison. The macrocyclic peptidomimetics showed considerable activity towards calpain II, cathepsin L and S, and the 20S proteasome chymotrypsin-like activity. Some of the first examples of highly potent macrocyclic inhibitors of cathepsin S were identified. These adopt a well-defined β-strand geometry as shown by NMR spectroscopy, X-ray analysis, and molecular docking studies.
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Affiliation(s)
- Ashok D Pehere
- School of Chemistry & Physics, The University of Adelaide, North Terrace, Adelaide, SA 5005, Australia
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27
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Chouhan G, James K. Efficient Construction of Proline-Containing β-Turn Mimetic Cyclic Tetrapeptides via CuAAC Macrocyclization. Org Lett 2013; 15:1206-9. [DOI: 10.1021/ol303572t] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Affiliation(s)
- Gagan Chouhan
- Department of Chemistry, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, United States
| | - Keith James
- Department of Chemistry, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, United States
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28
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Neilsen PM, Pehere AD, Pishas KI, Callen DF, Abell AD. New 26S proteasome inhibitors with high selectivity for chymotrypsin-like activity and p53-dependent cytotoxicity. ACS Chem Biol 2013. [PMID: 23190346 DOI: 10.1021/cb300549d] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The 26S proteasome has emerged over the past decade as an attractive therapeutic target in the treatment of cancers. Here, we report new tripeptide aldehydes that are highly specific for the chymotrypsin-like catalytic activity of the proteasome. These new specific proteasome inhibitors demonstrated high potency and specificity for sarcoma cells, with therapeutic windows superior to those observed for benchmark proteasome inhibitors, MG132 and Bortezomib. Constraining the peptide backbone into the β-strand geometry, known to favor binding to a protease, resulted in decreased activity in vitro and reduced anticancer activity. Using these new proteasome inhibitors, we show that the presence of an intact p53 pathway significantly enhances cytotoxic activity, thus suggesting that this tumor suppressor is a critical downstream mediator of cell death following proteasomal inhibition.
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Affiliation(s)
- Paul M. Neilsen
- Centre
for Personalised Cancer Medicine, Discipline of Medicine,
and ‡School of Chemistry
and Physics, The University of Adelaide, North Terrace,
Adelaide SA 5005, Australia
| | - Ashok D. Pehere
- Centre
for Personalised Cancer Medicine, Discipline of Medicine,
and ‡School of Chemistry
and Physics, The University of Adelaide, North Terrace,
Adelaide SA 5005, Australia
| | - Kathleen I. Pishas
- Centre
for Personalised Cancer Medicine, Discipline of Medicine,
and ‡School of Chemistry
and Physics, The University of Adelaide, North Terrace,
Adelaide SA 5005, Australia
| | - David F. Callen
- Centre
for Personalised Cancer Medicine, Discipline of Medicine,
and ‡School of Chemistry
and Physics, The University of Adelaide, North Terrace,
Adelaide SA 5005, Australia
| | - Andrew D. Abell
- Centre
for Personalised Cancer Medicine, Discipline of Medicine,
and ‡School of Chemistry
and Physics, The University of Adelaide, North Terrace,
Adelaide SA 5005, Australia
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29
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Pehere AD, Sumby CJ, Abell AD. New cylindrical peptide assemblies defined by extended parallel β-sheets. Org Biomol Chem 2013; 11:425-9. [DOI: 10.1039/c2ob26637g] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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30
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31
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Sokolova NV, Nenajdenko VG. Recent advances in the Cu(i)-catalyzed azide–alkyne cycloaddition: focus on functionally substituted azides and alkynes. RSC Adv 2013. [DOI: 10.1039/c3ra42482k] [Citation(s) in RCA: 116] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
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32
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Yu J, Horsley JR, Abell AD. The Influence of Secondary Structure on Electron Transfer in Peptides. Aust J Chem 2013. [DOI: 10.1071/ch13276] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
A series of synthetic peptides containing 0–5 α-aminoisobutyric acid (Aib) residues and a C-terminal redox-active ferrocene was synthesised and their conformations defined by NMR and circular dichroism. Each peptide was separately attached to an electrode for subsequent electrochemical analysis in order to investigate the effect of peptide chain length (distance dependence) and secondary structure on the mechanism of intramolecular electron transfer. While the shorter peptides (0–2 residues) do not adopt a well defined secondary structure, the longer peptides (3–5 residues) adopt a helical conformation, with associated intramolecular hydrogen bonding. The electrochemical results on these peptides clearly revealed a transition in the mechanism of intramolecular electron transfer on transitioning from the ill-defined shorter peptides to the longer helical peptides. The helical structures undergo electron transfer via a hopping mechanism, while the shorter ill-defined structures proceeded via an electron superexchange mechanism. Computational studies on two β-peptides PCB-(β3Val-β3Ala-β3Leu)n–NHC(CH3)2OOtBu (n = 1 and 2; PCB = p-cyanobenzamide) were consistent with these observations, where the n = 2 peptide adopts a helical conformation and the n = 1 peptide an ill-defined structure. These combined studies suggest that the mechanism of electron transfer is defined by the extent of secondary structure, rather than merely chain length as is commonly accepted.
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33
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Niu TF, Sun M, Lv MF, Yi WB, Cai C. Synthesis of highly functionalized macrocycles by tandem multicomponent reactions and intramolecular Sonogashira cross-coupling. Org Biomol Chem 2013; 11:7232-8. [DOI: 10.1039/c3ob41367e] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
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34
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35
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36
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37
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Londregan AT, Farley KA, Limberakis C, Mullins PB, Piotrowski DW. A new and useful method for the macrocyclization of linear peptides. Org Lett 2012; 14:2890-3. [PMID: 22612479 DOI: 10.1021/ol301173m] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
A new and useful procedure for the macrocyclization of linear peptides is described. The natural amino acid side chains of tyrosine (phenol), lysine (alkylamine), and histidine (imidazole) react in an intramolecular fashion with a pendent pyridine-N-oxide-carboxamide, which is selectively activated by the phosphonium salt, PyBroP. The reaction is mild, rapid, and efficient with a potentially large substrate scope. Multiple examples are provided with full characterization and analyses, including a novel aza-variant of the C-O-D ring system of vancomycin.
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Affiliation(s)
- Allyn T Londregan
- CVMED Medicinal Chemistry, Pfizer Inc., Eastern Point Road, Groton, Connecticut 06340, USA.
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