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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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Dolenc J, Haywood EJ, Zhu T, Smith LJ. Backbone N-Amination Promotes the Folding of β-Hairpin Peptides via a Network of Hydrogen Bonds. J Chem Inf Model 2022; 62:6704-6714. [PMID: 35816656 PMCID: PMC9795546 DOI: 10.1021/acs.jcim.2c00516] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Molecular dynamics (MD) simulations have been used to characterize the effects of backbone N-amination of residues in a model β-hairpin peptide. This modification is of considerable interest as N-aminated peptides have been shown to inhibit amyloid-type aggregation. Six derivatives of the β-hairpin peptide, which contain one, two, or four N-aminated residues, have been studied. For each peptide 100 ns MD simulations starting from the folded β-hairpin structure were performed. The effects of the N-amination prove to be very sequence dependent. N-Amination of a residue involved in interstrand hydrogen bonding (Val3) leads to unfolding of the β-hairpin, whereas N-amination of a residue toward the C-terminus (Leu11) gives fraying at the termini of the peptide. In the other derivatives the peptide remains folded, with increasing levels of N-amination reducing the right-handed twist of the β-hairpin and favoring population of a type II' rather than a type I' β-turn. MD simulations (100 ns) have also been run for each peptide starting from an unfolded extended chain. Here, the peptide with four N-aminated residues shows the most folding into the β-hairpin (34%). Analysis of the simulations shows that N-amination favors the population of β (φ, ψ) conformations by the preceding residue due to, at least in part, a network of weak NH2(i)-CO(i) and NH2(i)-CO(i-2) hydrogen bonds. It also leads to a reduction of misfolding because of changes in the hydrogen-bonding potential. Both of these features help funnel the peptide to the folded β-hairpin structure. The conformational insights provided through this work give a firm foundation for the design of N-aminated peptide inhibitors for modulating protein-protein interactions and aggregation.
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Affiliation(s)
- Jožica Dolenc
- Chemistry
- Biology
- Pharmacy Information Center, ETH Zurich, Zurich CH-8093, Switzerland
| | - Esme J. Haywood
- Inorganic
Chemistry Laboratory, Department of Chemistry, University of Oxford, South Parks Road, Oxford OX1 3QR, United Kingdom
| | - Tingting Zhu
- Inorganic
Chemistry Laboratory, Department of Chemistry, University of Oxford, South Parks Road, Oxford OX1 3QR, United Kingdom
| | - Lorna J. Smith
- Inorganic
Chemistry Laboratory, Department of Chemistry, University of Oxford, South Parks Road, Oxford OX1 3QR, United Kingdom, (L.J.S.)
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Makwana KM, Sarnowski MP, Miao J, Lin YS, Del Valle JR. N-Amination Converts Amyloidogenic Tau Peptides into Soluble Antagonists of Cellular Seeding. ACS Chem Neurosci 2021; 12:3928-3938. [PMID: 34609825 PMCID: PMC9035343 DOI: 10.1021/acschemneuro.1c00528] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The spread of neurofibrillary tangles composed of tau protein aggregates is a hallmark of Alzheimer's and related neurodegenerative diseases. Early oligomerization of tau involves conformational reorganization into parallel β-sheet structures and supramolecular assembly into toxic fibrils. Despite the need for selective inhibitors of tau propagation, β-rich protein assemblies are inherently difficult to target with small molecules. Here, we describe a minimalist approach to mimic the aggregation-prone modules within tau. We carried out a backbone residue scan and show that amide N-amination completely abolishes the tendency of these peptides to self-aggregate, rendering them soluble mimics of ordered β-strands from the tau R2 and R3 domains. Several N-amino peptides (NAPs) inhibit tau fibril formation in vitro. We further demonstrate that NAPs 12 and 13 are effective at blocking the cellular seeding of endogenous tau by interacting with monomeric or fibrillar forms of extracellular tau. Peptidomimetic 12 is serum stable, non-toxic to neuronal cells, and selectivity inhibits the fibrilization of tau over Aβ42. Structural analysis of our lead NAPs shows considerable conformational constraint imposed by the N-amino groups. The described backbone N-amination approach provides a rational basis for the mimicry of other aggregation-prone peptides that drive pathogenic protein assembly.
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Affiliation(s)
- Kamlesh M Makwana
- Department of Chemistry & Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, United States
| | - Matthew P Sarnowski
- Department of Chemistry & Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, United States
| | - Jiayuan Miao
- Department of Chemistry, Tufts University, Medford, Massachusetts 02155, United States
| | - Yu-Shan Lin
- Department of Chemistry, Tufts University, Medford, Massachusetts 02155, United States
| | - Juan R Del Valle
- Department of Chemistry & Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, United States
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Rathman BM, Rowe JL, Del Valle JR. Synthesis and conformation of backbone N-aminated peptides. Methods Enzymol 2021; 656:271-294. [PMID: 34325790 DOI: 10.1016/bs.mie.2021.04.013] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The chemical modification of peptides is a promising approach for the design of protein-protein interaction inhibitors and peptide-based drug candidates. Among several peptidomimetic strategies, substitution of the amide backbone maintains side-chain functionality that may be important for engagement of biological targets. Backbone amide substitution has been largely limited to N-alkylation, which can promote cis amide geometry and disrupt important H-bonding interactions. In contrast, N-amination of peptides induces distinct backbone geometries and maintains H-bond donor capacity. In this chapter we discuss the conformational characteristics of designed N-amino peptides and present a detailed protocol for their synthesis on solid support. The described methods allow for backbone N-amino scanning of biologically active parent sequences.
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Ahangarpour M, Kavianinia I, Harris PWR, Brimble MA. Photo-induced radical thiol-ene chemistry: a versatile toolbox for peptide-based drug design. Chem Soc Rev 2021; 50:898-944. [PMID: 33404559 DOI: 10.1039/d0cs00354a] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
While the global market for peptide/protein-based therapeutics is witnessing significant growth, the development of peptide drugs remains challenging due to their low oral bioavailability, poor membrane permeability, and reduced metabolic stability. However, a toolbox of chemical approaches has been explored for peptide modification to overcome these obstacles. In recent years, there has been a revival of interest in photoinduced radical thiol-ene chemistry as a powerful tool for the construction of therapeutic peptides.
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Affiliation(s)
- Marzieh Ahangarpour
- School of Chemical Sciences, The University of Auckland, 23 Symonds Street, Auckland 1010, New Zealand.
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Sun H, Chen D, Zhan S, Wu W, Xu H, Luo C, Su H, Feng Y, Shao W, Wan A, Zhou B, Wan G, Bu X. Design and Discovery of Natural Cyclopeptide Skeleton Based Programmed Death Ligand 1 Inhibitor as Immune Modulator for Cancer Therapy. J Med Chem 2020; 63:11286-11301. [PMID: 32844651 DOI: 10.1021/acs.jmedchem.0c01262] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Blockade of immune checkpoint PD-1/PD-L1 facilitates the rescue of immune escapes of tumor cells. Though various monoclonal antibodies have been approved for clinical therapy, the development of small molecular inhibitors lags behind antibodies partially owing to the challenges of protein-protein interaction (PPI) blocker design. In this work, we adopted the skeleton of natural cyclopeptidic antibiotics gramicidin S as the start point for PD-1/PD-L1 inhibitor exploring and discovered a series of novel cyclopeptides that could interfere with the PPI of PD-1/PD-L1 based on several rounds of structural design and optimization. The representative active cyclopeptide 66 can bind two PD-L1 and efficiently block the PD-1/PD-L1 interaction, recruit the immune cells to the tumor cells, enhance their killing against tumor cells by promoting the release of granzyme B and perforin, and display significant CD8+ T cell-dependent tumor suppression activity in vivo.
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Affiliation(s)
- Haixia Sun
- School of Pharmaceutical Sciences, Sun Yat-Sen University, Guangzhou 510006, China
| | - Daoyuan Chen
- Department of Bioengineering, Zhuhai Campus of Zunyi Medical University, Guangzhou 519041, China
| | - Siyue Zhan
- School of Pharmaceutical Sciences, Sun Yat-Sen University, Guangzhou 510006, China
| | - Weijian Wu
- School of Pharmaceutical Sciences, Sun Yat-Sen University, Guangzhou 510006, China
| | - Huiying Xu
- School of Pharmaceutical Sciences, Sun Yat-Sen University, Guangzhou 510006, China
| | - Chunxiang Luo
- School of Pharmaceutical Sciences, Sun Yat-Sen University, Guangzhou 510006, China
| | - Hui Su
- School of Pharmaceutical Sciences, Sun Yat-Sen University, Guangzhou 510006, China
| | - Yanqiao Feng
- School of Pharmaceutical Sciences, Sun Yat-Sen University, Guangzhou 510006, China
| | - Weiyan Shao
- School of Pharmaceutical Sciences, Sun Yat-Sen University, Guangzhou 510006, China
| | - Arabella Wan
- Department of Gastrointestinal Surgery, The First Affiliated Hospital, Sun Yat-Sen University, Guangzhou 510080, China
| | - Binhua Zhou
- School of Pharmaceutical Sciences, Sun Yat-Sen University, Guangzhou 510006, China.,School of Chinese Pharmacy, Guizhou Minzu University, Guiyang 550025, China
| | - Guohui Wan
- School of Pharmaceutical Sciences, Sun Yat-Sen University, Guangzhou 510006, China.,National-Local Joint Engineering Laboratory of Druggability and New Drugs Evaluation, National Engineering Research Center for New Drug and Druggability (Cultivation), Sun Yat-Sen University, Guangzhou 510006, China
| | - Xianzhang Bu
- School of Pharmaceutical Sciences, Sun Yat-Sen University, Guangzhou 510006, China
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