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Noki S, de la Torre BG, Albericio F. Safety-Catch Linkers for Solid-Phase Peptide Synthesis. Molecules 2024; 29:1429. [PMID: 38611709 PMCID: PMC11012524 DOI: 10.3390/molecules29071429] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2024] [Revised: 03/18/2024] [Accepted: 03/20/2024] [Indexed: 04/14/2024] Open
Abstract
Solid-phase peptide synthesis (SPPS) is the preferred strategy for synthesizing most peptides for research purposes and on a multi-kilogram scale. One key to the success of SPPS is the continual evolution and improvement of the original method proposed by Merrifield. Over the years, this approach has been enhanced with the introduction of new solid supports, protecting groups for amino acids, coupling reagents, and other tools. One of these improvements is the use of the so-called "safety-catch" linkers/resins. The linker is understood as the moiety that links the peptide to the solid support and protects the C-terminal carboxylic group. The "safety-catch" concept relies on linkers that are totally stable under the conditions needed for both α-amino and side-chain deprotection that, at the end of synthesis, can be made labile to one of those conditions by a simple chemical reaction (e.g., an alkylation). This unique characteristic enables the simultaneous use of two primary protecting strategies: tert-butoxycarbonyl (Boc) and fluorenylmethoxycarbonyl (Fmoc). Ultimately, at the end of synthesis, either acids (which are incompatible with Boc) or bases (which are incompatible with Fmoc) can be employed to cleave the peptide from the resin. This review focuses on the most significant "safety-catch" linkers.
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Affiliation(s)
- Sikabwe Noki
- Peptide Science Laboratory, School of Chemistry and Physics, University of KwaZulu-Natal, Westville, Durban 4000, South Africa;
- KwaZulu-Natal Research Innovation and Sequencing Platform (KRISP), School of Laboratory Medicine and Medical Sciences, College of Health Sciences, University of KwaZulu-Natal, Durban 4041, South Africa
| | - Beatriz G. de la Torre
- KwaZulu-Natal Research Innovation and Sequencing Platform (KRISP), School of Laboratory Medicine and Medical Sciences, College of Health Sciences, University of KwaZulu-Natal, Durban 4041, South Africa
| | - Fernando Albericio
- Peptide Science Laboratory, School of Chemistry and Physics, University of KwaZulu-Natal, Westville, Durban 4000, South Africa;
- CIBER-BBN, Networking Centre on Bioengineering, Biomaterials, and Nanomedicine, Department of Organic Chemistry, University of Barcelona, 08028 Barcelona, Spain
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2
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Kar A, Jana M, Malik V, Sarkar A, Mandal K. Total Chemical Synthesis of the SARS-CoV-2 Spike Receptor-Binding Domain. Chemistry 2024; 30:e202302969. [PMID: 37815536 DOI: 10.1002/chem.202302969] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2023] [Revised: 10/10/2023] [Accepted: 10/10/2023] [Indexed: 10/11/2023]
Abstract
SARS-CoV-2 and its global spread have created an unprecedented public health crisis. The spike protein of SARS-CoV-2 has gained significant attention due to its crucial role in viral entry into host cells and its potential as both a prophylactic and a target for therapeutic interventions. Herein, we report the first successful total synthesis of the SARS-CoV-2 spike protein receptor binding domain (RBD), highlighting the key challenges and the strategies employed to overcome them. Appropriate utilization of advanced solid phase peptide synthesis and cutting-edge native chemical ligation methods have facilitated the synthesis of this moderately large protein molecule. We discuss the problems encountered during the chemical synthesis and approaches taken to optimize the yield and the purity of the synthetic protein molecule. Furthermore, we demonstrate that the chemically synthesized homogeneous spike RBD efficiently binds to the known mini-protein binder LCB1. The successful chemical synthesis of the spike RBD presented here can be utilized to gain valuable insights into SARS-CoV-2 spike RBD biology, advancing our understanding and aiding the development of intervention strategies to combat future coronavirus outbreaks. The modular synthetic approach described in this study can be effectively implemented in the synthesis of other mutated variants or enantiomer of the spike RBD for mirror-image drug discovery.
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Affiliation(s)
- Abhisek Kar
- Tata Institute of Fundamental Research Hyderabad, 36/p Gopanpally, Hyderabad, Telangana, 500046, India
| | - Mrinmoy Jana
- Tata Institute of Fundamental Research Hyderabad, 36/p Gopanpally, Hyderabad, Telangana, 500046, India
| | - Vishal Malik
- Tata Institute of Fundamental Research Hyderabad, 36/p Gopanpally, Hyderabad, Telangana, 500046, India
| | - Arighna Sarkar
- Tata Institute of Fundamental Research Hyderabad, 36/p Gopanpally, Hyderabad, Telangana, 500046, India
| | - Kalyaneswar Mandal
- Tata Institute of Fundamental Research Hyderabad, 36/p Gopanpally, Hyderabad, Telangana, 500046, India
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3
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Abstract
Deposits of the microtubule-associated protein Tau (MAPT) serve as a hallmark of neurodegenerative diseases known as tauopathies. Numerous studies have demonstrated that in diseases such as Alzheimer's disease (AD), Tau undergoes extensive remodeling. The attachment of post-translational modifications distributed throughout the entire sequence of the protein correlates with clinical presentation. A systematic examination of these protein alterations can shed light on their roles in both healthy and diseased states. However, the ability to access these modifications in the entire protein chain is limited as Tau can only be produced recombinantly or through semisynthesis. In this article, we describe the first chemical synthesis of the longest 2N4R isoform of Tau, consisting of 441 amino acids. The 2N4R Tau was divided into 3 major segments and a total of 11 fragments, all of which were prepared via solid-phase peptide synthesis. The successful chemical strategy has relied on the strategic use of two cysteine sites (C291 and C322) for the native chemical ligations (NCLs). This was combined with modern preparative protein chemistries, such as mercaptothreonine ligation (T205), diselenide-selenoester ligation (D358), and mutations of mercaptoamino acids into native residues via homogeneous radical desulfurization (A40, A77, A119, A157, A246, and A390). The successful completion of the synthesis has established a robust and scalable route to the native protein in multimilligram quantities and high purity. In broader terms, the presented strategy can be applied to the preparation of other shorter isoforms of Tau as well as to introduce all post-translational modifications that are characteristic of tauopathies such as AD.
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Affiliation(s)
- Wyatt C Powell
- Department of Chemistry, University of Colorado, Boulder, Colorado 80309, United States
| | - Ruiheng Jing
- Department of Chemistry, University of Colorado, Boulder, Colorado 80309, United States
| | - Maciej A Walczak
- Department of Chemistry, University of Colorado, Boulder, Colorado 80309, United States
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4
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Hong ZZ, Yu RR, Zhang X, Webb AM, Burge NL, Poirier MG, Ottesen JJ. Development of Convergent Hybrid Phase Ligation for Efficient and Convenient Total Synthesis of Proteins. Pept Sci (Hoboken) 2023; 115:e24323. [PMID: 37692919 PMCID: PMC10488053 DOI: 10.1002/pep2.24323] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2023] [Accepted: 05/16/2023] [Indexed: 09/12/2023]
Abstract
Simple and efficient total synthesis of homogeneous and chemically modified protein samples remains a significant challenge. Here, we report development of a convergent hybrid phase native chemical ligation (CHP-NCL) strategy for facile preparation of proteins. In this strategy, proteins are split into ~100-residue blocks, and each block is assembled on solid support from synthetically accessible peptide fragments before ligated together into full-length protein in solution. With the new method, we increase the yield of CENP-A synthesis by 2.5-fold compared to the previous hybrid phase ligation approach. We further extend the new strategy to the total chemical synthesis of 212-residue linker histone H1.2 in unmodified, phosphorylated, and citrullinated forms, each from eight peptide segments with only one single purification. We demonstrate that fully synthetic H1.2 replicates the binding interactions of linker histones to intact mononucleosomes, as a proxy for the essential function of linker histones in the formation and regulation of higher order chromatin structure.
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Affiliation(s)
- Ziyong Z. Hong
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio, 43210
| | - Ruixuan R. Yu
- Ohio State Biochemistry Graduate Program, The Ohio State University, Columbus, Ohio, 43210
| | - Xiaoyu Zhang
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio, 43210
| | - Allison M. Webb
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio, 43210
| | - Nathaniel L. Burge
- Ohio State Biochemistry Graduate Program, The Ohio State University, Columbus, Ohio, 43210
| | - Michael G. Poirier
- Ohio State Biochemistry Graduate Program, The Ohio State University, Columbus, Ohio, 43210
- Department of Physics, Department of Chemistry & Biochemistry, The Ohio State University, Columbus, Ohio, 43210
| | - Jennifer J. Ottesen
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio, 43210
- Ohio State Biochemistry Graduate Program, The Ohio State University, Columbus, Ohio, 43210
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5
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Mannuthodikayil J, Sinha S, Singh S, Biswas A, Ali I, Mashurabad PC, Tabassum W, Vydyam P, Bhattacharyya MK, Mandal K. A Chimeric Peptide Inhibits Red Blood Cell Invasion by Plasmodium falciparum with Hundredfold Increased Efficacy. Chembiochem 2022; 24:e202200533. [PMID: 36449557 DOI: 10.1002/cbic.202200533] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2022] [Revised: 11/29/2022] [Accepted: 11/30/2022] [Indexed: 12/05/2022]
Abstract
Inhibiting the formation of a tight junction between two malaria parasite proteins, apical membrane antigen 1 and rhoptry neck protein 2, crucial for red blood cell invasion, prevents progression of the disease. In this work, we have used a unique approach to design a chimeric peptide, prepared by fusion of the best features of two peptide inhibitors, that has displayed parasite growth inhibition ex vivo with nanomolar IC50 , which is 100 times better than any of its parent peptides. Furthermore, to gain structural insights, we computationally modelled the hybrid peptide on its receptor.
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Affiliation(s)
- Jamsad Mannuthodikayil
- Tata Institute of Fundamental Research Hyderabad, 36/p Gopanpally, Hyderabad, Telangana, 500046, India
| | - Suman Sinha
- Tata Institute of Fundamental Research Hyderabad, 36/p Gopanpally, Hyderabad, Telangana, 500046, India
| | - Sameer Singh
- Tata Institute of Fundamental Research Hyderabad, 36/p Gopanpally, Hyderabad, Telangana, 500046, India
| | - Anamika Biswas
- Tata Institute of Fundamental Research Hyderabad, 36/p Gopanpally, Hyderabad, Telangana, 500046, India
| | - Irshad Ali
- Tata Institute of Fundamental Research Hyderabad, 36/p Gopanpally, Hyderabad, Telangana, 500046, India
| | - Purna Chandra Mashurabad
- Department of Biochemistry, School of Life Sciences, University of Hyderabad, Gachibowli, Hyderabad, 500046, India
| | - Wahida Tabassum
- Department of Biochemistry, School of Life Sciences, University of Hyderabad, Gachibowli, Hyderabad, 500046, India
| | - Pratap Vydyam
- Department of Biochemistry, School of Life Sciences, University of Hyderabad, Gachibowli, Hyderabad, 500046, India
| | - Mrinal Kanti Bhattacharyya
- Department of Biochemistry, School of Life Sciences, University of Hyderabad, Gachibowli, Hyderabad, 500046, India
| | - Kalyaneswar Mandal
- Tata Institute of Fundamental Research Hyderabad, 36/p Gopanpally, Hyderabad, Telangana, 500046, India
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6
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Sánchez-Campillo I, Miguel-Gracia J, Karamanis P, Blanco-Canosa JB. A versatile o-aminoanilide linker for native chemical ligation. Chem Sci 2022; 13:10904-10913. [PMID: 36320694 PMCID: PMC9491214 DOI: 10.1039/d2sc04158h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2022] [Accepted: 08/25/2022] [Indexed: 12/04/2022] Open
Abstract
Chemical protein synthesis (CPS) is a consolidated field founded on the high chemospecificity of amide-forming reactions, most notably the native chemical ligation (NCL), but also on new technologies such as the Ser/Thr ligation of C-terminal salicylaldehyde esters and the α-ketoacid-hydroxylamine (KAHA) condensation. NCL was conceptually devised for the ligation of peptides having a C-terminal thioester and an N-terminal cysteine. The synthesis of C-terminal peptide thioesters has attracted a lot of interest, resulting in the invention of a wide diversity of different methods for their preparation. The N-acylurea (Nbz) approach relies on the use of the 3,4-diaminobenzoic (Dbz–COOH) and the 3-amino-(4-methylamino)benzoic (MeDbz–COOH) acids; the latter disclosed to eliminate the formation of branching peptides. Dbz–COOH has been also used for the development of the benzotriazole (Bt)-mediated NCL, in which the peptide–Dbz–CONH2 precursor is oxidized to a highly acylating peptide–Bt–CONH2 species. Here, we have brought together the Nbz and Bt approaches in a versatile linker, the 1,2-diaminobenzene (Dbz). The Dbz combines the robustness of MeDbz–COOH and the flexibility of Dbz–COOH: it can be converted into the Nbz or Bt C-terminal peptides. Both are ligated in high yields, and the reaction intermediates can be conveniently characterized. Our results show that the Bt precursors have faster NCL kinetics that is reflected by a rapid transthioesterification (<5 min). Taking advantage of this major acylating capacity, peptide–Bt can be transselenoesterified in the presence of selenols to afford peptide selenoesters which hold enormous potential in NCL. Peptide–(o-aminoanilides) prepared on a solid phase yield peptide–Nbz and peptide–Bt. Both undergo thioesterification in the presence of thiols, as well as selenoesterification in peptide–Bt. They are readily used in NCL for protein synthesis.![]()
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Affiliation(s)
- Iván Sánchez-Campillo
- Institute for Advanced Chemistry of Catalonia (IQAC-CSIC) Jordi Girona 18-26 08034 Barcelona Spain
| | - Judit Miguel-Gracia
- Institute for Advanced Chemistry of Catalonia (IQAC-CSIC) Jordi Girona 18-26 08034 Barcelona Spain
| | - Periklis Karamanis
- Dept. of Chemistry "G. Ciamician", University of Bologna Via Selmi 2 40126 Bologna Italy
| | - Juan B Blanco-Canosa
- Institute for Advanced Chemistry of Catalonia (IQAC-CSIC) Jordi Girona 18-26 08034 Barcelona Spain
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7
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Biswas A, Raran-Kurussi S, Narayan A, Kar A, Chandra Mashurabad P, Bhattacharyya MK, Mandal K. Efficient refolding and functional characterization of PfAMA1(DI+DII) expressed in E. coli. Biochem Biophys Rep 2021; 26:100950. [PMID: 33665380 PMCID: PMC7907217 DOI: 10.1016/j.bbrep.2021.100950] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2020] [Revised: 01/18/2021] [Accepted: 02/04/2021] [Indexed: 11/30/2022] Open
Abstract
Apical membrane antigen 1 (AMA1) is a surface protein of Plasmodium sp. that plays a crucial role in forming moving junction (MJ) during the invasion of human red blood cells. The obligatory presence of AMA1 in the parasite lifecycle designates this protein as a potential vaccine candidate and an essential target for the development of novel peptide or protein therapeutics. However, due to multiple cysteine residues in the protein sequence, attaining the native fold with correct disulfide linkages during the refolding process after expression in bacteria has remained challenging for years. Although several approaches to obtain the refolded protein from bacterial expression have been reported previously, achieving high yield during refolding and proper functional validation of the expressed protein was lacking. We report here an improved method of refolding to obtain higher quantity of refolded protein. We have also validated the refolded protein's functional activity by evaluating the expressed AMA1 protein binding with a known inhibitory peptide, rhoptry neck protein 2 (RON2), using surface plasmon resonance (SPR) and isothermal titration calorimetry (ITC). A simple yet effective protocol for P. falciparum AMA1 protein expression from E. coli. Highly reproducible and scalable refolding protocol. The modified refolding method uses a step-wise dialysis technique. Functional validation of the refolded protein shown by binding with PfRON2 ectodomain using SPR and ITC.
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Affiliation(s)
- Anamika Biswas
- TIFR Centre for Interdisciplinary Sciences, Tata Institute of Fundamental Research Hyderabad, 36/p Gopanpally, Hyderabad, Telangana 500046, India
| | - Sreejith Raran-Kurussi
- TIFR Centre for Interdisciplinary Sciences, Tata Institute of Fundamental Research Hyderabad, 36/p Gopanpally, Hyderabad, Telangana 500046, India
| | - Akash Narayan
- TIFR Centre for Interdisciplinary Sciences, Tata Institute of Fundamental Research Hyderabad, 36/p Gopanpally, Hyderabad, Telangana 500046, India
| | - Abhisek Kar
- TIFR Centre for Interdisciplinary Sciences, Tata Institute of Fundamental Research Hyderabad, 36/p Gopanpally, Hyderabad, Telangana 500046, India
| | - Purna Chandra Mashurabad
- Department of Biochemistry, School of Life Sciences, University of Hyderabad, Gachibowli, Hyderabad, Telangana 500046, India
| | - Mrinal Kanti Bhattacharyya
- Department of Biochemistry, School of Life Sciences, University of Hyderabad, Gachibowli, Hyderabad, Telangana 500046, India
| | - Kalyaneswar Mandal
- TIFR Centre for Interdisciplinary Sciences, Tata Institute of Fundamental Research Hyderabad, 36/p Gopanpally, Hyderabad, Telangana 500046, India
- Corresponding author.
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8
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Ferrer‐Gago FJ, Koh LQ. Synthesis of
C‐terminal
glycine‐rich
o
‐aminoanilide
peptides without overacylation for use in
benzotriazole‐mediated
native chemical ligation. Pept Sci (Hoboken) 2020. [DOI: 10.1002/pep2.24194] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Affiliation(s)
- Fernando J. Ferrer‐Gago
- p53 Laboratory Agency for Science Technology and Research (A*STAR), 8A Biomedical Grove #06‐04/05 Neuro/Immunos 138648 Singapore
| | - Li Quan Koh
- p53 Laboratory Agency for Science Technology and Research (A*STAR), 8A Biomedical Grove #06‐04/05 Neuro/Immunos 138648 Singapore
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9
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Kar A, Mannuthodikayil J, Singh S, Biswas A, Dubey P, Das A, Mandal K. Efficient Chemical Protein Synthesis using Fmoc-Masked N-Terminal Cysteine in Peptide Thioester Segments. Angew Chem Int Ed Engl 2020; 59:14796-14801. [PMID: 32333711 PMCID: PMC7891605 DOI: 10.1002/anie.202000491] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2020] [Revised: 03/27/2020] [Indexed: 01/23/2023]
Abstract
We report an operationally simple method to facilitate chemical protein synthesis by fully convergent and one-pot native chemical ligations utilizing the fluorenylmethyloxycarbonyl (Fmoc) moiety as an N-masking group of the N-terminal cysteine of the middle peptide thioester segment(s). The Fmoc group is stable to the harsh oxidative conditions frequently used to generate peptide thioesters from peptide hydrazide or o-aminoanilide. The ready availability of Fmoc-Cys(Trt)-OH, which is routinely used in Fmoc solid-phase peptide synthesis, where the Fmoc group is pre-installed on cysteine residue, minimizes additional steps required for the temporary protection of the N-terminal cysteinyl peptides. The Fmoc group is readily removed after ligation by short exposure (<7 min) to 20 % piperidine at pH 11 in aqueous conditions at room temperature. Subsequent native chemical ligation reactions can be performed in presence of piperidine in the same solution at pH 7.
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Affiliation(s)
- Abhisek Kar
- TIFR Centre for Interdisciplinary SciencesTata Institute of Fundamental Research Hyderabad36/p GopanpallyHyderabad500046TelanganaIndia
| | - Jamsad Mannuthodikayil
- TIFR Centre for Interdisciplinary SciencesTata Institute of Fundamental Research Hyderabad36/p GopanpallyHyderabad500046TelanganaIndia
| | - Sameer Singh
- TIFR Centre for Interdisciplinary SciencesTata Institute of Fundamental Research Hyderabad36/p GopanpallyHyderabad500046TelanganaIndia
| | - Anamika Biswas
- TIFR Centre for Interdisciplinary SciencesTata Institute of Fundamental Research Hyderabad36/p GopanpallyHyderabad500046TelanganaIndia
| | - Puneet Dubey
- TIFR Centre for Interdisciplinary SciencesTata Institute of Fundamental Research Hyderabad36/p GopanpallyHyderabad500046TelanganaIndia
| | - Amit Das
- Protein Crystallography Section, Radiation Biology and Health Sciences DivisionBhabha Atomic Research CentreTrombayMumbai400085India
- Homi Bhabha National InstituteAnushaktinagarMumbai400094India
| | - Kalyaneswar Mandal
- TIFR Centre for Interdisciplinary SciencesTata Institute of Fundamental Research Hyderabad36/p GopanpallyHyderabad500046TelanganaIndia
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10
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11
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Kar A, Mannuthodikayil J, Singh S, Biswas A, Dubey P, Das A, Mandal K. Efficient Chemical Protein Synthesis using Fmoc‐Masked N‐Terminal Cysteine in Peptide Thioester Segments. Angew Chem Int Ed Engl 2020. [DOI: 10.1002/ange.202000491] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Abhisek Kar
- TIFR Centre for Interdisciplinary Sciences Tata Institute of Fundamental Research Hyderabad 36/p Gopanpally Hyderabad Telangana −500046 India
| | - Jamsad Mannuthodikayil
- TIFR Centre for Interdisciplinary Sciences Tata Institute of Fundamental Research Hyderabad 36/p Gopanpally Hyderabad Telangana −500046 India
| | - Sameer Singh
- TIFR Centre for Interdisciplinary Sciences Tata Institute of Fundamental Research Hyderabad 36/p Gopanpally Hyderabad Telangana −500046 India
| | - Anamika Biswas
- TIFR Centre for Interdisciplinary Sciences Tata Institute of Fundamental Research Hyderabad 36/p Gopanpally Hyderabad Telangana −500046 India
| | - Puneet Dubey
- TIFR Centre for Interdisciplinary Sciences Tata Institute of Fundamental Research Hyderabad 36/p Gopanpally Hyderabad Telangana −500046 India
| | - Amit Das
- Protein Crystallography Section, Radiation Biology and Health Sciences Division Bhabha Atomic Research Centre Trombay Mumbai 400085 India
- Homi Bhabha National Institute Anushaktinagar Mumbai 400094 India
| | - Kalyaneswar Mandal
- TIFR Centre for Interdisciplinary Sciences Tata Institute of Fundamental Research Hyderabad 36/p Gopanpally Hyderabad Telangana −500046 India
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12
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Abboud SA, Aucagne V. An optimized protocol for the synthesis of N-2-hydroxybenzyl-cysteine peptide crypto-thioesters. Org Biomol Chem 2020; 18:8199-8208. [PMID: 33034311 DOI: 10.1039/d0ob01737j] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
We herein report a robust upgraded synthetic protocol for the synthesis of N-Hnb-Cys crypto-thioester peptides, useful building blocks for segment-based chemical protein synthesis through native chemical ligation. We recently observed the formation of an isomeric co-product when using a different solid support than the originally-reported one, thus hampering the general applicability of the methodology. We undertook a systematic study to characterize this compound and identify the parameters favouring its formation. We show here that epimerization from l- to d-cysteine occurred during the key solid-supported reductive amination step. We also observed the formation of imidazolidinones by-products arising from incomplete reduction of the imine. Structural characterization combined with the deciphering of underlying reaction mechanisms allowed us to optimize conditions that abolished the formation of all these side-products.
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Affiliation(s)
- Skander A Abboud
- Centre de Biophysique Moléculaire, CNRS UPR 4301, Rue Charles Sadron, 45071, Orléans cedex 2, France.
| | - Vincent Aucagne
- Centre de Biophysique Moléculaire, CNRS UPR 4301, Rue Charles Sadron, 45071, Orléans cedex 2, France.
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