Statine-based peptidomimetic compounds as inhibitors for SARS-CoV-2 main protease (SARS-CoV­2 Mpro).

COVID-19 is a multisystemic disease caused by the SARS-CoV-2 airborne virus, a member of the Coronaviridae family. It has a positive sense single-stranded RNA genome and encodes two non-structural proteins through viral cysteine-proteases processing. Blocking this step is crucial to control virus replication. In this work, we reported the synthesis of 23 statine-based peptidomimetics to determine their ability to inhibit the main protease (Mpro) activity of SARS-CoV-2. Among the 23 peptidomimetics, 15 compounds effectively inhibited Mpro activity by 50% or more, while three compounds (7d, 8e, and 9g) exhibited maximum inhibition above 70% and IC50 < 1 µM. Compounds 7d, 8e, and 9g inhibited roughly 80% of SARS-CoV-2 replication and proved no cytotoxicity. Molecular docking simulations show putative hydrogen bond and hydrophobic interactions between specific amino acids and these inhibitors. Molecular dynamics simulations further confirmed the stability and persisting interactions in Mpro's subsites, exhibiting favorable free energy binding (ΔGbind) values. These findings suggest the statine-based peptidomimetics as potential therapeutic agents against SARS-CoV-2 by targeting Mpro.

Synthesis and biological evaluation of novel peptidomimetic inhibitors of the coronavirus 3C-like protease.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), and related variants, are responsible for the devastating coronavirus disease 2019 (COVID-19) pandemic. The SARS-CoV-2 main protease (Mpro) plays a central role in the replication of the virus and represents an attractive drug target. Herein, we report the discovery of novel SARS-CoV-2 Mpro covalent inhibitors, including highly effective compound NIP-22c which displays high potency against several key variants and clinically relevant nirmatrelvir Mpro E166V mutants.

Smart Electrospun Nanofibers from Short Peptidomimetics Based on Pyrrolo-pyrazole Scaffold.

We prepared a small library of short peptidomimetics based on 3-pyrrolo-pyrazole carboxylate, a non-coded γ-amino acid, and glycine or alanine. The robust and eco-friendly synthetic approach adopted allows to obtain the dipeptides in two steps from commercial starting materials. This gives the possibility to shape these materials by electrospinning into micro- and nanofibers, in amounts required to be useful for coating surfaces of biomedical relevance. To promote high quality of electrospun fibers, different substitution patterns were evaluated, all for pure peptide fibers, free of any polymer or additive. The best candidate, which affords a homogeneous fibrous matrix, was prepared in larger amounts, and its biocompatibility was verified. This successful work is the first step to develop a new biomaterial able to produce pristine peptide-based nanofibers to be used as helpful component or stand-alone scaffolds for tissue engineering or for the surface modification of medical devices.

Understanding the Structural Requirements of Peptide-Protein Interaction and Applications for Peptidomimetic Development.

Protein-protein interaction is at the heart of most biological processes, and small peptides that bind to protein binding sites are resourceful tools to explore and understand the structural requirements for these interactions. In that sense, phage display is a well-suited technology to study protein-protein interactions, as it allows for unbiased screening of billions of peptides in search for those that interact with a protein binding domain. Here, we will illustrate how two distinct but complementary approaches, phage display and nuclear magnetic resonance (NMR), can be utilized to unveil structural details of peptide-protein interaction. Finally, knowledge derived from phage mutagenesis and NMR studies can be streamlined for quick peptidomimetic design and synthesis using the retroinversion approach to validate using in vitro and in vivo assays the therapeutic potential of peptides identified by phage display.

Reavaliação do nirmatrelvir/ritonavir para o tratamento de pacientes com COVID-19 não hospitalizados e com alto risco de doença grave / Revalidation of nirmatrelvir/ritonavir for the treatment of patients with COVID-19 who are not hospitalized and with a high risk of serious illness

INTRODUÇÃO: Pacientes com fatores de risco como idade avançada, imunodepressão, obesidade e doenças cardiovasculares têm risco aumentado de internação, intubação e morte. De acordo com dados brasileiros, o risco de morte por covid-19 aumenta com o número de fatores de risco que o paciente apresenta, sendo igual a 17% em pacientes com 2 fatores de risco e 76% na presença de 8 fatores de risco. Além disso, mesmo aqueles pacientes que sobrevivem a uma internação em terapia intensiva frequentemente enfrentam sequelas e representam alto custo para o sistema público. O medicamento nirmatrelvir associado ao ritonavir têm o objetivo de prevenir internações, complicações e morte. Ele é indicado para pacientes com Covid-19 leve a moderada, não hospitalizados, até 5 dias do início dos sintomas. Apesar dos avanços da vacinação no Brasil, evidências sobre a falha vacinal em idosos e imunodeprimidos destacam a importância da disponibilidade de alternativas terapêuticas para essas populações. O presente relatório teve por objetivo avaliar evidências sobre a efetividade do tratamento em pacientes vacinados com alto risco de agravamento da doença. PERGUNTA: O medicamento nirmatrelvir/ritonavir é eficaz, seguro e custo-efetivo para pacientes com covid19 leve a moderada não hospitalizados vacinados que apresentam alto risco de agravamento da doença? EVIDÊNCIAS CLÍNICAS: Resultados obtidos a partir de estudos observacionais de mundo real confirmaram os resultados do ensaio clínico do medicamento nirmatrelvir/ritonavir, demonstrando que o tratamento de pacientes de grupos de risco é capaz de reduzir o risco de desfechos desfavoráveis como internação e óbito entre cerca de 50% e 70%, inclusive entre pacientes previamente vacinados. ANÁLISE DE IMPACTO ORÇAMENTÁRIO: A análise de impacto orçamentário do relatório de recomendação do nirmatrelvir/ritonavir foi atualizada considerando-se o cenário atual da pandemia no Brasil. De acordo com a nova análise, o uso do nirmatrelvir/ritonavir por pacientes com idade ≥ 65 anos e imunossuprimidos com idade ≥ 18 anos, resultaria em uma economia de recursos de R$ 408.957.111,38 em 5 anos. Ressalta-se, no entanto, que devido à dinâmica de difícil previsão da pandemia, este montante está sujeito à incerteza. Considerando-se a análise realizada anteriormente no relatório de recomendação, pode-se concluir que o montante economizado se reduz proporcionalmente à redução do número de casos da doença na população alvo. CONSIDERAÇÕES FINAIS: De acordo com as evidências atualmente disponíveis, o uso do nirmatrelvir/ritonavir é efetivo e seguro para pacientes com covid-19 leve a moderada não hospitalizados vacinados que apresentam alto risco de agravamento da doença. O impacto orçamentário está sujeito a incertezas já que o número de casos da doença no horizonte temporal da análise é de difícil previsão. RECOMENDAÇÃO PRELIMINAR DA CONITEC: Diante do exposto, os membros do Comitê de Medicamentos da Conitec, em sua 16ª Reunião Extraordinária, realizada no dia 1º de novembro de 2023, deliberaram que a matéria fosse disponibilizada em Consulta Pública com recomendação preliminar favorável à incorporação no SUS do nirmatrelvir/ritonavir para o tratamento de pacientes com Covid-19 não hospitalizados com idade a partir de 65 anos ou pacientes imunossuprimidos a partir de 18 anos de idade. Os membros do Comitê concordaram na manutenção da indicação de uso, não havendo ampliação do público-alvo, justificada pela restrição orçamentária, considerando que há incremento de custo da aquisição da tecnologia, ainda que haja economia de recursos ao serem evitadas internações e óbitos. CONSULTA PÚBLICA: Das nove contribuições recebidas, cinco contribuições foram de cunho técnico-científico e quatro contribuições de experiência ou opinião. Todas as contribuições concordaram com a recomendação preliminar da Conitec de incorporar o nirmatrelvir/ritonavir. Duas contribuições técnico-científicassugeriram ampliação da população elegível ao tratamento com o medicamento com a inclusão de indicação para pacientes com taxa de filtração glomerular menor que 30 ml/min/1,73m2 e de pacientes adultos com asma grave independentemente da faixa etária. Uma contribuição técnico-científica enviada pela empresa fabricante do medicamento expressou sua concordância com e solicitou a inclusão de informaçõea adicionais no relatório. As contribuições de experiência ou opinião ressaltaram a eficácia e segurança do medicamento para a população alvo. RECOMEDAÇÃO FINAL DA CONITEC: Diante do exposto, os membros do Comitê de Medicamentos, presentes na 126ª Reunião Ordinária da Conitec, realizada no dia 01 de fevereiro de 2024, deliberaram, por unanimidade, após reavaliação, manter a incorporação do nirmatrelvir/ritonavir, no SUS, para o tratamento da Covid-19 nos seguintes grupos de pacientes com sintomas leves a moderados, que não requerem oxigênio suplementar, independentemente do status vacinal: a) imunocomprometidos com idade ≥ 18 anos; b) com idade ≥ 65 anos. Foi assinado o registro de deliberação nº 874/2024. DECISÃO: manter a incorporação, no âmbito do Sistema Único de Saúde - SUS, de nirmatrelvir/ritonavir para o tratamento da Covid-19 para pacientes com sintomas leves a moderados, que não requerem oxigênio suplementar, independentemente do status vacinal e com idade igual ou superior a 65 anos ou imunocomprometidos com idade igual ou superior a 18 anos, publicada no Diário Oficial da União nº 46, seção 1, página 54, em 07 de março de 2024.

Ligand-Based Design of Selective Peptidomimetic uPA and TMPRSS2 Inhibitors with Arg Bioisosteres.

Trypsin-like serine proteases are involved in many important physiological processes like blood coagulation and remodeling of the extracellular matrix. On the other hand, they are also associated with pathological conditions. The urokinase-pwlasminogen activator (uPA), which is involved in tissue remodeling, can increase the metastatic behavior of various cancer types when overexpressed and dysregulated. Another member of this protease class that received attention during the SARS-CoV 2 pandemic is TMPRSS2. It is a transmembrane serine protease, which enables cell entry of the coronavirus by processing its spike protein. A variety of different inhibitors have been published against both proteases. However, the selectivity over other trypsin-like serine proteases remains a major challenge. In the current study, we replaced the arginine moiety at the P1 site of peptidomimetic inhibitors with different bioisosteres. Enzyme inhibition studies revealed that the phenylguanidine moiety in the P1 site led to strong affinity for TMPRSS2, whereas the cyclohexylguanidine derivate potently inhibited uPA. Both inhibitors exhibited high selectivity over other structurally similar and physiologically important proteases.

Peptidomimetics as potent dual SARS-CoV-2 cathepsin-L and main protease inhibitors: In silico design, synthesis and pharmacological characterization.

In this paper we present the design, synthesis, and biological evaluation of a new series of peptidomimetics acting as potent anti-SARS-CoV-2 agents. Starting from our previously described Main Protease (MPro) and Papain Like Protease (PLPro) dual inhibitor, CV11, here we disclose its high inhibitory activity against cathepsin L (CTSL) (IC50 = 19.80 ± 4.44 nM), an emerging target in SARS-CoV-2 infection machinery. An in silico design, inspired by the structure of CV11, led to the development of a library of peptidomimetics showing interesting activities against CTSL and Mpro, allowing us to trace the chemical requirements for the binding to both enzymes. The screening in Vero cells infected with 5 different SARS-CoV-2 variants of concerns, highlighted sub-micromolar activities for most of the synthesized compounds (13, 15, 16, 17 and 31) in agreement with the enzymatic inhibition assays results. The compounds showed lack of activity against several different RNA viruses except for the 229E and OC43 human coronavirus strains, also characterized by a cathepsin-L dependent release into the host cells. The most promising derivatives were also evaluated for their chemical and metabolic in-vitro stability, with derivatives 15 and 17 showing a suitable profile for further preclinical characterization.

Protocol for reconstituting peptides/peptidomimetics from DMSO to aqueous buffers for circular dichroism analyses.

Circular dichroism (CD) spectrometry is a rapid technique for detecting protein secondary structure, particularly helicity. DMSO is used to ensure optimal solubility of peptides/peptidomimetics; however, its background absorbance hinders effective CD analysis. Here, we present a protocol for reconstituting peptides/peptidomimetics from DMSO to aqueous buffers for CD analyses. We describe steps for identifying chemicals that induce DMSO evaporation, extracting peptides/peptidomimetics from DMSO, and CD spectrometer setup and analysis. We then detail procedures for secondary structure analyses of reconstituted peptides/peptidomimetics. For complete details on the use and execution of this protocol, please refer to Gao et al. (2023).1.

Molecular insights into the dynamic modulation of bacterial ClpP function and oligomerization by peptidomimetic boronate compounds.

Bacterial caseinolytic protease P subunit (ClpP) is important and vital for cell survival and infectivity. Recent publications describe and discuss the complex structure-function relationship of ClpP and its processive activity mediated by 14 catalytic sites. Even so, there are several aspects yet to be further elucidated, such as the paradoxical allosteric modulation of ClpP by peptidomimetic boronates. These compounds bind to all catalytic sites, and in specific conditions, they stimulate a dysregulated degradation of peptides and globular proteins, instead of inhibiting the enzymatic activity, as expected for serine proteases in general. Aiming to explore and explain this paradoxical effect, we solved and refined the crystal structure of native ClpP from Staphylococcus epidermidis (Se), an opportunistic pathogen involved in nosocomial infections, as well as ClpP in complex with ixazomib at 1.90 Å and 2.33 Å resolution, respectively. The interpretation of the crystal structures, in combination with complementary biochemical and biophysical data, shed light on how ixazomib affects the ClpP conformational state and activity. Moreover, SEC-SAXS and DLS measurements show, for the first time, that a peptidomimetic boronate compound also induces the assembly of the tetradecameric structure from isolated homomeric heptameric rings of a gram-positive organism.

Targeted therapy, immunotherapy, and small molecules and peptidomimetics as emerging immunoregulatory agents for melanoma.

Primary cutaneous melanoma is the most lethal of all skin neoplasms and its incidence is increasing. Clinical management of advanced melanoma in the last decade has been revolutionised by the availability of immunotherapies and targeted therapies, used alone and in combination. This article summarizes advances in the treatment of late-stage melanoma including use of protein kinase inhibitors, antibody-based immune checkpoint inhibitors, adoptive immunotherapy, vaccines and more recently, small molecules and peptidomimetics as emerging immunoregulatory agents.

Whey proteins as multifunctional food materials: Recent advancements in hydrolysis, separation, and peptidomimetic approaches.

Whey protein derived bioactives, including α-lactalbumin, ß-lactoglobulin, bovine serum albumin, lactoferrin, transferrin, and proteose-peptones, have exhibited wide ranges of functional, biological and therapeutic properties varying from anticancer, antihypertensive, and antimicrobial effects. In addition, their functional properties involve gelling, emulsifying, and foaming abilities. For these reasons, this review article is framed to understand the relationship existed in between those compound levels and structures with their main functional, biological, and therapeutic properties exhibited either in vitro or in vivo. The impacts of hydrolysis mechanism and separation techniques in enhancing those properties are likewise discussed. Furthermore, special emphasize is given to multifunctional effects of whey derived bioactives and their future trends in ameliorating further food, pharmaceutical, and nutraceutical products. The underlying mechanism effects of those properties are still remained unclear in terms of activity levels, efficacy, and targeted effectiveness. For these reasons, some important models linking to functional properties, thermal properties and cell circumstances are established. Moreover, the coexistence of radical trapping groups, chelating groups, sulfhydryl groups, inhibitory groups, and peptide bonds seemed to be the key elements in triggering those functions and properties. Practical Application: Whey proteins are the byproducts of cheese processing and usually the exploitation of these food waste products has increasingly getting acceptance in many countries, especially European countries. Whey proteins share comparable nutritive values to milk products, particularly on their richness on important proteins that can serve immune protection, structural, and energetic roles. The nutritive profile of whey proteins shows diverse type of bioactive molecules like α-lactalbumin, ß-lactoglobulin, lactoferrin, transferrin, immunoglobulin, and proteose peptones with wide biological importance to the living system, such as in maintaining immunological, neuronal, and signaling roles. The diversification of proteins of whey products prompted scientists to exploit the real mechanisms behind of their biological and therapeutic effects, especially in declining the risk of cancer, tumor, and further complications like diabetes type 2 and hypertension risk effects. For these reasons, profiling these types of proteins using different proteomic and peptidomic approaches helps in determining their biological and therapeutic targets along with their release into gastrointestinal tract conditions and their bioavailabilities into portal circulation, tissue, and organs. The wide applicability of those protein fractions and their derivative bioactive products showed significant impacts in the field of emulsion and double emulsion stabilization by playing roles as emulsifying, surfactant, stabilizing, and foaming agents. Their amphoteric properties helped them to act as excellent encapsulating agents, particularly as vehicle for delivering important vitamins and bioactive compounds. The presence of ferric elements increased their transportation to several metal-ions in the same time increased their scavenging effects to metal-transition and peroxidation of lipids. Their richness with almost essential and nonessential amino acids makes them as selective microbial starters, in addition their richness in sulfhydryl amino acids allowed them to act a cross-linker in conjugating further biomolecules. For instance, conjugating gold-nanoparticles and fluorescent materials in targeting diseases like cancer and tumors in vivo is considered the cutting-edges strategies for these versatile molecules due to their active diffusion across-cell membrane and the presence of specific transporters to these therapeutic molecules.

Cooperative dissolution of peptidomimetic vesicles and amyloid ß fibrils.

The aggregation of amyloid proteins in the brain is a significant neurotoxic event that contributes to neurodegenerative disorders. The aggregation of amyloid beta (Aß), particularly Aß42 monomers, into various forms such as oligomers, protofibrils, fibrils, and amyloid plaques is a key pathological feature in Alzheimer's disease. As a result, Aß42 is a primary target and the development of molecular strategies for the dissolution of Aß42 aggregates is considered a promising approach to mitigating Alzheimer's disease pathology. A set of pyrene-conjugated peptidomimetics derived from Aß14-23 (AkdcPy, AkdmPy, and AkdnPy) by incorporating an unnatural amino acid [kd: cyclo(Lys-Asp)] were studied for their ability to modulate Aß42 aggregation. AkdcPy and AkdmPy formed vesicular structures in aqueous media. The vesicles of AkdmPy loaded with the neuroprotective compound berberine (Ber), dissipated mutually in the presence of preformed Aß42 fibrils. During this process, the active drug Ber was released. This work is expected to inspire the development of drug-loaded peptidomimetic-based therapeutic formulations to modulate disorders associated with amyloid toxicity.

Palladium-Mediated S-Arylation of Cysteine Residues with 4-[18F]Fluoroiodobenzene ([18F]FIB).

Transition-metal-mediated bioconjugation chemistry has been used extensively to design and synthesize molecular probes to visualize, characterize, and quantify biological processes within intact living organisms at the cellular and subcellular levels. We demonstrate the development and validation of chemoselective [18F]fluoro-arylation chemistry of cysteine residues using Pd-mediated S-arylation chemistry with 4-[18F]fluoroiodobenzene ([18F]FIB) as an aryl electrophile. The novel bioconjugation technique proceeded in excellent radiochemical yields of 73-96% within 15 min under ambient and aqueous reaction mixture conditions, representing a versatile novel tool for decorating peptides and peptidomimetics with short-lived positron emitter 18F. The chemoselective S-arylation of several peptides and peptidomimetics containing multiple reactive functional groups confirmed the versatility and functional group compatibility. The synthesis and radiolabeling of a novel prostate-specific membrane antigen (PSMA) binding radioligand [18F]6 was accomplished using the novel labeling protocol. The validation of radioligand [18F]6 in a preclinical prostate cancer model with PET resulted in favorable accumulation and retention in PSMA-expressing LNCaP tumors. At the same time, a significantly lower salivary gland uptake was observed compared to clinical PSMA radioligand [18F]PSMA-1007. This finding coincides with ongoing discussions about the molecular basis of the off-target accumulation of PSMA radioligands currently used for clinical imaging and therapy of prostate cancer.

Hepatitis C: The Story of a Long Journey through First, Second, and Third Generation NS3/4A Peptidomimetic Inhibitors. What Did We Learn?

Hepatitis C viral (HCV) infection is the leading cause of liver failure and still represents a global health burden. Over the past decade, great advancements made HCV curable, and sustained viral remission significantly improved to more than 98%. Historical treatment with pegylated interferon alpha and ribavirin has been displaced by combinations of direct-acting antivirals. These regimens include drugs targeting different stages of the HCV life cycle. However, the emergence of viral resistance remains a big concern. The design of peptidomimetic inhibitors (PIs) able to fit and fill the conserved substrate envelope region within the active site helped avoid contact with the vulnerable sites of the most common resistance-associated substitutions Arg155, Ala156, and Asp168. Herein, we give an overview of HCV NS3 PIs discovered during the past decade, and we deeply discuss the rationale behind the structural optimization efforts essential to achieve pangenotypic activity.

Synthetic Peptides and Peptidomimetics: From Basic Science to Biomedical Applications-Second Edition.

Peptides are increasingly emerging as a drug class for a wide range of human diseases due to their intrinsic properties, such as excellent recognition abilities and biocompatibility [...].

Biaryl carboxamide-based peptidomimetics analogs as potential pancreatic lipase inhibitors for treating obesity.

A series of 1,1'-biphenyl-3-carboxamide and furan-phenyl-carboxamide analogs were synthesized using an optimized scheme and confirmed by 1H and 13C nuclear magnetic resonance and high-resolution mass spectrometry techniques. The synthesized peptidomimetics analogs were screened in vitro to understand the inhibitory potential of pancreatic lipase (PL). Analogs were assessed for the PL inhibitory activity based on interactions, geometric complementarity, and docking score. Among the synthesized analogs, 9, 29, and 24 were found to have the most potent PL inhibitory activity with IC50 values of 3.87, 4.95, and 5.34 µM, respectively, compared to that of the standard drug, that is, orlistat, which inhibits PL with an IC50 value of 0.99 µM. The most potent analog, 9, exhibited a competitive-type inhibition with an inhibition constant (Ki) of 2.72 µM. In silico molecular docking of analog 9 with the PL (PDB ID:1LPB) showed a docking score of -11.00 kcal/mol. Analog 9 formed crucial hydrogen bond interaction with Ser152, His263, π-cation interaction with Asp79, Arg256, and π-π stacking with Phe77, Tyr114 at the protein's active site. The molecular dynamic simulation confirmed that analog 9 forms stable interactions with PL at the end of 200 ns with root mean square deviation values of 2.5 and 6 Å. No toxicity was observed for analog 9 (concentration range of 1-20 µM) when tested by MTT assay in RAW 264.7 cells.

Recent Discovery of Peptidomimetics for the Treatment of Coronavirus (COVID-19), Human Coronavirus, and Enteroviruses.

This patent describes the synthesis of compounds, methods, and compositions for preventing, treating, and/or curing Covid-19, human coronavirus, and enterovirus infections. Some peptidomimetic compounds are very potent and could be a game changer in new treatment therapy for COVID-19.

Advances in MRI: Peptide and peptidomimetic-based contrast agents.

Magnetic resonance imaging (MRI) is a common medical imaging technique that provides three-dimensional body images. MRI contrast agents improve image contrast by raising the rate of water proton relaxation in specific tissues. Peptides and peptidomimetics act as scaffolds for MRI imaging agents because of their increased size and offer the possibility to engine a higher hydration value within the design. The design of a new Gd-based contrast agent must take into account high stability constants to avoid free Gd(III), with the subsequent nephrotoxicity, and high relaxivity values. This review analyzes various synthetic approaches, reports studies of relaxometric parameters, and focuses on the description and application of Gd(III)-chelates based on peptide and peptidomimetic scaffolds. In addition, the X-ray molecular structures of three DOTA complexes will be reported to emphasize the necessity of using the X-ray diffraction analysis to identify the coordination sphere of the metals and the mechanism of action of the compounds.

Structure-based design of peptidomimetic inhibitors of PSD-95 with improved affinity for the PDZ3 domain.

Aberrant brain-derived neurotrophic factor (BDNF) signaling has been proposed to contribute to the pathophysiology of depression and other neurological disorders such as Angelman syndrome. We have previously shown that targeting the tropomyosin receptor kinase B/postsynaptic density protein-95 (PSD-95) nexus in the BDNF signaling pathway by peptidomimetic inhibitors is a promising approach for therapeutic intervention. Here, we used structure-based knowledge to develop a new Syn3 peptidomimetic compound series that fuses peptides derived from the PSD-95-binding protein SynGAP to our prototype compound CN2097. The new compounds target the PSD-95 PDZ3 domain and adjoining αC helix to achieve bivalent binding that results in up to 7-fold stronger affinity compared to CN2097. These compounds were designed to improve CN2097 specificity for the PSD-95 PDZ3 domain, and structure-activity relationship studies were performed to improve their resistance to proteolysis.

Inhibition of Aurora-A/N-Myc Protein-Protein Interaction Using Peptidomimetics: Understanding the Role of Peptide Cyclization.

Using N-Myc61-89 as a starting template we showcase the systematic use of truncation and maleimide constraining to develop peptidomimetic inhibitors of the N-Myc/Aurora-A protein-protein interaction (PPI); a potential anticancer drug discovery target. The most promising of these - N-Myc73-94-N85C/G89C-mal - is shown to favour a more Aurora-A compliant binding ensemble in comparison to the linear wild-type sequence as observed through fluorescence anisotropy competition assays, circular dichroism (CD) and nuclear magnetic resonance (NMR) experiments. Further in silico investigation of this peptide in its Aurora-A bound state, by molecular dynamics (MD) simulations, imply (i) the bound conformation is more stable as a consequence of the constraint, which likely suppresses dissociation and (ii) the constraint may make further stabilizing interactions with the Aurora-A surface. Taken together this work unveils the first orthosteric N-Myc/Aurora-A inhibitor and provides useful insights on the biophysical properties and thus design of constrained peptides, an attractive therapeutic modality.