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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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Nandhini KP, Noki S, Brasil E, Albericio F, de la Torre BG. A safety-catch protecting group strategy compatible with Boc-chemistry for the synthesis of peptide nucleic acids (PNAs). Org Biomol Chem 2023; 21:8125-8135. [PMID: 37772422 DOI: 10.1039/d3ob01348k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/30/2023]
Abstract
Peptide Nucleic Acids (PNAs) are an intriguing class of synthetic biomolecules with great potential in medicine. Although PNAs could be considered analogs of oligonucleotides, their synthesis is more like that of peptides. In both cases, a Solid-Phase Synthesis (SPS) approach is used. Herein, the advantage using Boc as a temporal protecting group has been demonstrated to be more favored than Fmoc. In this context, a new PNA SPS strategy has been developed based on a safety-catch protecting group scheme for the exocyclic nitrogen of the side-chain bases and the linker. Sulfinyl (sulfoxide)-containing moieties are fully stable to the trifluoroacetic acid (TFA) used to remove the Boc group, but they can be reduced to the corresponding sulfide derivatives, which are labile in the presence of TFA. The efficiency of this novel synthetic strategy has been demonstrated in the synthesis of the PNA pentamer H-PNA(TATCT)-βAla-OH.
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Affiliation(s)
- K P Nandhini
- 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.
- Peptide Science Laboratory, School of Chemistry and Physics, University of KwaZulu-Natal, Westville, Durban 4000, South Africa.
| | - Sikabwe Noki
- 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.
- Peptide Science Laboratory, School of Chemistry and Physics, University of KwaZulu-Natal, Westville, Durban 4000, South Africa.
| | - Edikarlos Brasil
- Peptide Science Laboratory, School of Chemistry and Physics, University of KwaZulu-Natal, Westville, Durban 4000, 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, and Department of Organic Chemistry, University of Barcelona, Martí i Franqués 1-11, 08028 Barcelona, Spain
| | - 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.
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Nandhini KP, Albericio F, de la Torre BG. 2-Methoxy-4-methylsulfinylbenzyl Alcohol as a Safety-Catch Linker for the Fmoc/ tBu Solid-Phase Peptide Synthesis Strategy. J Org Chem 2022; 87:9433-9442. [PMID: 35801570 DOI: 10.1021/acs.joc.2c01057] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Fmoc and Boc group are the two main groups used to protect the α-amino function in Solid-Phase Peptide Synthesis (SPPS). In this regard, the use of the Mmsb linker allows the combination of these two groups. Peptide-O-Mmsb-Resin is stable to the piperidine and trifluoroacetic acid (TFA) treatment used to remove Fmoc and Boc, respectively. The peptide is detached in a two-step protocol, namely reduction of the sulfoxide to the sulfide with Me3SiCl and Ph3P, and then treatment with TFA. The advantage of this strategy has been demonstrated by the following: preparation of peptide with no diketopiperazine formation in sequences prone to this side reaction; on-resin cyclization without the concourse of common organic reagents such as Pd(0) but of difficult use in a biological laboratory; and on-resin disulfide formation in a total side-chain unprotected peptide. The use of Mmsb linker together with Msib (4-(methylsulfinyl)benzyl) and Msbh (4,4'-bis(methylsulfinyl)benzhydryl) described in the accompanying manuscript add a fourth dimension to the SPPS protecting group scheme.
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Affiliation(s)
- K P Nandhini
- 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
| | - Fernando Albericio
- Peptide Science Laboratory, School of Chemistry and Physics, University of KwaZulu-Natal, Westville, Durban 4000, South Africa.,Institute for Advanced Chemistry of Catalonia (IQAC-CSIC), Jordi Girona 18-26, 08034 Barcelona, Spain.,CIBER-BBN, Networking Centre on Bioengineering, Biomaterials and Nanomedicine, and Department of Organic Chemistry, University of Barcelona, Martí i Franqués 1-11, 08028 Barcelona, Spain
| | - 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
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