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In this work the identification of peptides derived from quinoa proteins which could potentially self-assemble, and form hydrogels was carried out with TANGO, a statistical mechanical based algorithm that predicts ß-aggregate propensity of peptides. Peptides with the highest aggregate propensity were subjected to gelling screening experiments from which the most promising bioactive peptide with sequence KIVLDSDDPLFGGF was selected. The self-assembling and hydrogelation properties of the C-terminal amidated peptide (KIVLDSDDPLFGGF-NH2) were studied. The effect of concentration, pH, and temperature on the secondary structure of the peptide were probed by circular dichroism (CD), while its nanostructure was studied by transmission electron microscopy (TEM) and small-angle neutron scattering (SANS). Results revealed the existence of random coil, α-helix, twisted ß-sheet, and well-defined ß-sheet secondary structures, with a range of nanostructures including elongated fibrils and bundles, whose proportion was dependant on the peptide concentration, pH, or temperature. The self-assembly of the peptide is demonstrated to follow established models of amyloid formation, which describe the unfolded peptide transiting from an α-helix-containing intermediate into ß-sheet-rich protofibrils. The self-assembly is promoted at high concentrations, elevated temperatures, and pH values close to the peptide isoelectric point, and presumably mediated by hydrogen bond, hydrophobic and electrostatic interactions, and π-π interactions (from the F residue). At 15 mg/mL and pH 3.5, the peptide self-assembled and formed a self-supporting hydrogel exhibiting viscoelastic behaviour with G' (1 Hz) ~2300 Pa as determined by oscillatory rheology measurements. The study describes a straightforward method to monitor the self-assembly of plant protein derived peptides; further studies are needed to demonstrate the potential application of the formed hydrogels in food and biomedicine.
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Chenopodium quinoa , Nanoestruturas , Peptídeos/química , Hidrogéis/química , Estrutura Secundária de Proteína , Nanoestruturas/química , Dicroísmo CircularRESUMO
Peptide and protein selective modification at tyrosine residues has become an exploding field of research as tyrosine constitutes a robust alternative to lysine and cysteine-targeted traditional peptide/protein modification protocols. This review offers a comprehensive summary of the latest advances in tyrosine-selective cleavage, functionalization, and conjugation of peptides and proteins from the past three years. This updated overview complements the extensive body of work on site-selective modification of peptides and proteins, which holds significant relevance across various disciplines, including chemical, biological, medical, and material sciences.
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Re-assembled casein micelles (rCMs), were formulated in the 1970s as a model system to understand native casein micelles (nCMs) in milk. These early works allowed an understanding of the critical factors involved in the formation of rCMs, such as minerals (citrate, phosphate, and calcium), casein type (αs-, ß-, and κ-casein) and the extent of their phosphorylation. rCMs were also used to understand the effect of treatments such as ethanol, high hydrostatic pressure and heating on the stability and integrity of the micelles. More recently, the applications of rCMs have been investigated, these include their use as a nanocarrier of bioactive molecules and as electrode-bound substrates to monitor chymosin activity by electrochemistry, to cite a few. Moreover, the potential to use rCMs in both food and non-food applications remains to be fully exploited. The advantage of choosing rCMs over nCMs as an encapsulant and a lucrative food ingredient is due to their more efficient preparation and being free from impurities. In this review, we report on the formulation of rCMs, their physico-chemical properties and their behavior under different physico-chemical treatments, along with the applications and challenges of rCMs in food systems and their industrial production as a dairy ingredient.
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A novel tyrosine hyperoxidation enabling selective peptide cleavage is reported. The scission of the N-terminal amide bond of tyrosine was achieved with Dess-Martin periodinane under mild conditions, generating a C-terminal peptide fragment bearing the unprecedented hyperoxidized tyrosine motif, 4,5,6,7-tetraoxo-1H-indole-2-carboxamide, along with an intact N-terminal peptide fragment. This reaction proceeds with high site-selectivity for tyrosine and exhibits broad substrate scope for various peptides, including those containing post-translational modifications. More importantly, this oxidative cleavage was successfully applied to enable sequencing of three naturally occurring cyclic peptides, including one depsipeptide and one lipopeptide. The linearized peptides generated from the cleavage reaction significantly simplify cyclic peptide sequencing by MS/MS, thus providing a robust tool to facilitate rapid sequence determination of diverse cyclic peptides containing tyrosine. Furthermore, the highly electrophilic nature of the hyperoxidized tyrosine unit disclosed in this work renders it an important electrophilic target for the selective bioconjugation or synthetic manipulation of peptides containing this unit.
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In this work we report the synthesis of mono lipidated peptides containing a 3-mercaptopropionate linker in the N-terminus by means of a photoinitiated thiol-ene reaction (S-lipidation). We evaluate the self-assembling and hydrogelation properties of a library of mono S-lipidated peptides containing lipid chains of various lengths and demonstrate that hydrogelation was driven by a balance between the lipid chain's hydrophobicity and the peptide's facial hydrophobicity. We further postulate that a simple calculation using estimated values of log D could be used as a predictor of hydrogelation when designing similar systems. A mono S-lipidated peptide containing a short lipid chain that formed hydrogels was fully characterized and a mechanism for the peptide hydrogelation developed. Finally, we demonstrate that the presence of the thioether group in the mono S-lipidated peptide hydrogels, which is a feature lacking in conventional N-acyl lipidated systems, enables the controlled disassembly of the gel via oxidation to the sulfoxide by reactive oxygen species in accordance with a hydrophobicity-modulated strategy. Thus, we conclude that mono S-lipidated peptide hydrogels constitute a novel and simple tool for the development of tissue engineering and targeted drug delivery applications of diseases with overexpression of reactive oxygen species (e.g. degenerative and metabolic diseases, and cancers).
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HidrogéisRESUMO
The effect of installing different lipid chains (C6, C8, C10, and C16) on the N-terminus of an octapeptide derived from the antiparallel ß-interface of the diaminopimelate decarboxylase protein homotetramer has been investigated. Notably, the C8 peptide conjugate assembled into wide twisted nanoribbons and formed hydrogels, which to the best of our knowledge constitutes the first example of a peptide containing an eight carbon alkyl chain that demonstrates these properties, a space typically occupied by peptide amphiphiles with long lipid chains. Furthermore, this self-assembling lipopeptide exhibited pH and temperature stability with shear thinning properties suitable for biomedical applications. Importantly, in this work the application of the polystyrene-based sorbent Diaion™ HP20SS for the simple large-scale purification of self-assembling peptides is presented as an alternative to the use of time-consuming and labor-intensive reverse-phase high-performance liquid chromatography. STATEMENT OF SIGNIFICANCE: Peptides that can self-assemble into defined nanostructures are highly attractive for many biomedical applications given their unique physical and chemical properties. It is recognized that self-assembling peptides derived from naturally occurring proteins offer an unlimited source of functionalities and structures, which are hard to uncover with designed sequences. In this study, we have investigated the effect of installing different lipids chains on the N-terminus of an octapeptide derived from the antiparallel ß-interface of the diaminopimelate decarboxylase protein homo tetramer. We also reported the use of polymeric Diaionâ HP20SS beads as an alternative solid support to purify self-assembling peptides.
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Nanoestruturas , Nanotubos de Carbono , Hidrogéis , LipopeptídeosRESUMO
Increased water solubility and long-range intermolecular ordering have been introduced into the fluorescent organic molecule thiophene-diketopyrrolopyrrole (TDPP) via its conjugation to the octapeptide HEFISTAH, which is derived from the protein-protein ß-interface of the homo-tetramer protein diaminopimelate decarboxylase. The octapeptide, and its TDPP mono- and cross-linked conjugates were synthesised using 9-fluorenylmethoxycarbonyl (Fmoc) based solid-phase peptide synthesis (SPPS). Unlike the unmodified peptide, the resulting mono-linked and cross-linked peptides showed a fibrous morphology and formed hydrogels at 4 wt% in water at neutral pH, but failed to assemble at pH 2 and pH 9. Further peptide characterization showed that the TDPP organic core enhances peptide self-assembly and that both peptides assembled into fibers with a parallel ß-sheet structure. Furthermore, UV-vis spectroscopic analysis suggests that the TDPP molecules form H-type aggregates where the chromophores are likely to be co-facially packed, but rotationally and/or laterally offset from one another. This intermolecular coupling indicates that π-π stacking interactions are highly likely - a favourable sign for charge transport. The enhanced aqueous solubility and self-assembling properties of the TDPP-peptide conjugates allowed the successful preparation of thin films. Atomic force microscopy, X-ray diffraction and UV-vis spectroscopic analysis of these thin films revealed that the hybrid materials retained a fibrous morphology, ß-sheet structures and strong intermolecular coupling between neighbouring TDPP molecules. These results open an exciting avenue for bio-organic materials development, through structural and electronic tuning of the TDPP core.
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Peptídeos , Pirróis , Hidrogéis , Concentração de Íons de Hidrogênio , CetonasRESUMO
The use of peptide hydrogels is of growing interest in bone regeneration. Self-assembling peptides form hydrogels and can be used as injectable drug delivery matrices. Injected into the defect site, they can gel in situ, and release factors that aid bone growth. We report on the design, synthesis and characterization of three ß-hairpin peptide hydrogels, and on their osteoblast cytocompatibility as well as delivery of the lactoferrin glycoprotein, a bone anabolic factor. Osteoblasts cultured in hydrogels of the peptide with sequence NH2-Leu-His-Leu-His-Leu-Lys-Leu-Lys-Val-dPro-Pro-Thr-Lys-Leu-Lys-Leu-His-Leu-His-Leu-Arg-Gly-Asp-Ser-CONH2 (H4LMAX-RGDS) increased the osteoblast cell number and the cells appeared healthy after seven days. Furthermore, we showed that H4LMAX-RGDS was capable of releasing up to 60% of lactoferrin (pre-encapsulated in the gel) over five days while retaining the rest of the glycoprotein. Thus, H4LMAX-RGDS hydrogels are cytocompatible with primary osteoblasts and capable of delivering bio-active lactoferrin that increases osteoblast cell number.
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Wollamides are cyclic hexapeptides, recently isolated from an Australian soil Streptomyces isolate, that exhibit promising in vitro antimycobacterial activity against Mycobacterium bovis Bacille Calmette Guérin without displaying cytotoxicity against a panel of mammalian cells. Here, we report the synthesis and antimycobacterial activity of 36 new synthetic wollamides, collated with all known synthetic and natural wollamides, to reveal structure characteristics responsible for in vitro growth-inhibitory activity against Mycobacterium tuberculosis (H37Rv, H37Ra, CDC1551, HN878, and HN353). The most potent antimycobacterial wollamides were those where residue VI d-Orn (wollamide B) was replaced by d-Arg (wollamide B1) or d-Lys (wollamide B2), with all activity being lost when residue VI was replaced by Gly, l-Arg, or l-Lys (wollamide B3). Substitution of other amino acid residues mainly reduced or ablated antimycobacterial activity. Significantly, whereas wollamide B2 was the most potent in restricting M. tuberculosisin vitro, wollamide B1 restricted M. tuberculosis intracellular burden in infected macrophages. Wollamide B1 synergized with pretomanid (PA-824) in inhibiting M. tuberculosisin vitro growth but did not antagonize prominent first- and second-line tuberculosis antibiotics. Furthermore, wollamide B1 exerted bactericidal activity against nonreplicating M. tuberculosis and impaired growth of multidrug- and extensively drug-resistant clinical isolates. In vivo pharmacokinetic profiles for wollamide B1 in rats and mice encourage further optimization of the wollamide pharmacophore for in vivo bioavailability. Collectively, these observations highlight the potential of the wollamide antimycobacterial pharmacophore.
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Mycobacterium tuberculosis/efeitos dos fármacos , Peptídeos Cíclicos/farmacologia , Tuberculose/tratamento farmacológico , Animais , Linhagem Celular Tumoral , Farmacorresistência Bacteriana Múltipla/genética , Células Hep G2 , Humanos , Macrófagos/microbiologia , Camundongos , Camundongos Endogâmicos C57BL , Testes de Sensibilidade Microbiana , Estrutura Molecular , Mycobacterium tuberculosis/crescimento & desenvolvimento , Mycobacterium tuberculosis/isolamento & purificação , Ratos , Relação Estrutura-AtividadeRESUMO
The development of synthetic methods to prepare conformationally constrained peptides and peptide-polyketide hybrids remain an important chemical challenge. It is known that structural rigidity correlates with the specificity, bioactivity, and stability of these peptide systems, thus rigid systems are particularly attractive leads for development of potent biopharmaceuticals. Herein we provide an overview of recent developments in the syntheses of naturally derived constrained peptides and peptide-polyketide hybrids, with a particular emphasis on those systems containing an ene-like bond.
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Produtos Biológicos/síntese química , Peptídeos Cíclicos/síntese química , Policetídeos/síntese química , Técnicas de Síntese em Fase Sólida/métodos , Alcaloides/síntese química , Alcaloides/química , Alfa-Amanitina/síntese química , Alfa-Amanitina/química , Sequência de Aminoácidos , Aminoácidos/síntese química , Aminoácidos/química , Produtos Biológicos/química , Iminas/síntese química , Iminas/química , Compostos Macrocíclicos/síntese química , Compostos Macrocíclicos/química , Conformação Molecular , Peptídeos Cíclicos/química , Policetídeos/químicaRESUMO
The proposed structure of talarolide A, a cycloheptapeptide featuring a hydroxamate moiety within the peptide backbone, was successfully synthesized. An initial attempt to synthesize a linear peptide precursor containing a C-terminal N-benzyloxy glycine residue was problematic due to an unreported on-resin reduction of N-benzyloxy glycine to glycine. After repositioning the peptide cyclization point, a new linear peptide sequence was successfully prepared using Fmoc-solid-phase peptide synthesis. Subsequent solution-phase cyclization and removal of protecting groups furnished the synthetic talarolide A in good yield. Despite the mismatch of the NMR data between the synthetic talarolide A and the natural product, a detailed structural analysis using 2D NMR spectroscopy, together with re-synthesis of the same synthetic material using two additional cyclization sites, confirmed that our synthetic product has the reported structure of talarolide A.
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The first synthesis of the anti-TB cyclic peptide callyaerinâ A (1), containing a rare (Z)-2,3-diaminoacrylamide bridging motif, is reported. Fmoc-formylglycine-diethylacetal was used as a masked equivalent of formylglycine in the synthesis of the linear precursor to 1. Intramolecular cyclization between the formylglycine residue and the N-terminal amine in the linear peptide precursor afforded the macrocyclic natural product 1. Synthetic 1 possessed potent anti-TB activity (MIC100 =32â µm) while its all-amide congener was inactive. Variable-temperature NMR studies of both the natural product and its all-amide analogue revealed the extraordinary rigidity imposed by this diaminoacrylamide unit on peptide conformation. The work reported herein pinpoints the intrinsic role that the (Z)-2,3-diaminoacrylamide moiety confers on peptide bioactivity.
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Antituberculosos/síntese química , Produtos Biológicos/síntese química , Peptídeos Cíclicos/síntese química , Acrilamida/química , Sequência de Aminoácidos , Aminoácidos/química , Catálise , Ciclização , Oxirredução , Conformação ProteicaRESUMO
There is an increasing demand for biocompatible materials in biomedical applications. Herein, we report a modified α-helical decapeptide segment from the cardiac troponin C, which self-assembles into fibers with a secondary ß-sheet structure. These fibers cross-link via a novel supramolecular threading mechanism which results in an atypical stiff hydrogel (G' ≈ 13 kPa). In this work, we provide a first insight into the understanding of such remarkable cross-linking mechanism, which will aid in the development of new biomaterials with unique properties.
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We report the design and characterization of a peptide that assembles as ß-hairpins and forms hydrogels under physiological conditions. These hydrogels formed both in the absence and presence of several metal ions and displayed characteristic sheer-thinning properties. In particular, in the presence of Zn2+, we observed a novel hydrogel that proceeded via an intermolecular metal-coordination mechanism - intermolecular assembly that was previously reported instead to promote amyloid type aggregates.
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Hidrogel de Polietilenoglicol-Dimetacrilato/química , Peptídeos/química , Zinco/química , Sequência de Aminoácidos , Modelos Moleculares , Conformação Proteica em Folha betaRESUMO
We report the synthesis and characterization of multifunctional peptides comprised of a hydrogel forming ß-sheet peptide segment and a matrix metalloproteinase 2 substrate containing a propargylglycinyl linker that is further derivatized with an RGD peptide sequence via "click" chemistry. In contrast to currently known systems, these multifunctional peptides formed gels that are stiffer than those formed by their respective precursors. All the peptides showed reversible thermoresponsive properties, which render them as suitable lead systems for a variety of possible biomedical applications. STATEMENT OF SIGNIFICANCE: In general, it has been frequently observed that chemical biofunctionalization of peptide hydrogels adversely affects peptide assembly, hydrogel formation or mechanical properties, which severely compromises their application. A functionalization protocol that allows to generate peptide hydrogels that display significantly improved mechanical properties over their unfunctionalized counterparts is reported in this work. These peptides also showed thermoresponsive viscoelastic characteristics, including an example of a peptide hydrogel that displays lower critical solution temperature behaviour.
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Hidrogéis/química , Peptídeos/química , Temperatura , Cromatografia Líquida de Alta Pressão , Dicroísmo Circular , Metaloproteinase 2 da Matriz/metabolismo , Peptídeos/síntese química , Espalhamento a Baixo Ângulo , Espectroscopia de Infravermelho com Transformada de Fourier , Difração de Raios XRESUMO
Many secretory tissues release Zn(II) ions along with other molecules in response to external stimuli. Here we demonstrate that secretion of Zn(II) ions from normal, healthy prostate tissue is stimulated by glucose in fasted mice and that release of Zn(II) can be monitored by MRI. An â¼50% increase in water proton signal enhancement is observed in T1-weighted images of the healthy mouse prostate after infusion of a Gd-based Zn(II) sensor and an i.p. bolus of glucose. Release of Zn(II) from intracellular stores was validated in human epithelial prostate cells in vitro and in surgically exposed prostate tissue in vivo using a Zn(II)-sensitive fluorescent probe known to bind to the extracellular surface of cells. Given the known differences in intracellular Zn(II) stores in healthy versus malignant prostate tissues, the Zn(II) sensor was then evaluated in a transgenic adenocarcinoma of the mouse prostate (TRAMP) model in vivo. The agent proved successful in detecting small malignant lesions as early as 11 wk of age, making this noninvasive MR imaging method potentially useful for identifying prostate cancer in situations where it may be difficult to detect using current multiparametric MRI protocols.
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Meios de Contraste/administração & dosagem , Imageamento por Ressonância Magnética/métodos , Neoplasias da Próstata/diagnóstico por imagem , Zinco/metabolismo , Animais , Modelos Animais de Doenças , Corantes Fluorescentes , Humanos , Masculino , Camundongos , Próstata/diagnóstico por imagem , Próstata/metabolismo , Neoplasias da Próstata/metabolismo , Neoplasias da Próstata/patologia , Zinco/químicaRESUMO
Peptide based hydrogels have received much attention due to their potential biomedical applications. The majority of the gel forming peptides present a ß-sheet motif that is composed of alternating hydrophobic/hydrophilic amino acids. Furthermore, structural characterization of the assembly of these ß-sheet peptides has been refined recently. However, the relationship between peptide residue composition, molecular structure and the mechanical properties of the resulting hydrogel is not entirely understood. In this review, an analysis of the structural features of different ß-sheet peptide hydrogels and their mechanical properties is discussed, in order to provide further insight on the molecular features that are relevant for the design of effective ß-peptide hydrogels.
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Hidrogel de Polietilenoglicol-Dimetacrilato/química , Peptídeos/química , Conformação Proteica em Folha beta , Fenômenos Mecânicos , Modelos MolecularesRESUMO
The first syntheses of the naturally occurring cyclic peptides dianthin I (1), pseudostellarin A (2), and heterophyllin J (3) are described. The linear protected peptide precursors were prepared efficiently via Fmoc-solid-phase synthesis and subsequently cyclized in solution under dilute conditions. The structures of the synthetic cyclopentapeptides were confirmed by NMR spectroscopy and mass spectrometry and were in agreement with the literature data reported for the natural products.
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Dianthus/química , Peptídeos Cíclicos/isolamento & purificação , Estrutura Molecular , Peptídeos Cíclicos/química , Técnicas de Síntese em Fase SólidaRESUMO
The human cardiac troponin C peptide fragment H-V(9)EQLTEEQKNEFKAAFDIFVLGA(31)-OH, which covers helix-A in the native protein, self-assembles into ß-sheet fibrils in solution. These fibrils further entangle to give a hydrogel. This peptide may therefore serve as a template for development of novel biomaterials.
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Hidrogel de Polietilenoglicol-Dimetacrilato/química , Hidrogel de Polietilenoglicol-Dimetacrilato/síntese química , Fragmentos de Peptídeos/química , Fragmentos de Peptídeos/síntese química , Peptídeos/química , Peptídeos/síntese química , Troponina C/química , Humanos , Modelos Moleculares , Estrutura Secundária de Proteína , Difração de Raios XRESUMO
Mycobacterium tuberculosis is the causative agent of tuberculosis (TB), an infection that has been declared a global public health emergency by the World Health Organization. Current anti-TB therapies are limited in their efficacy and have failed to prevent the spread of TB, due to the long term drug compliance required and the genesis of multidrug-resistant strains (MDR). The number of chemotherapeutic agents currently available to treat MDR is limited, therefore there is a great need for new anti-TB drugs. Anti-TB peptides and peptidomimetics have emerged as an important and growing class of chemotherapeutic agents. This mini-review provides an update on peptides that exhibit very potent anti-TB activity, and their chemical syntheses, which could potentially be included in the pipeline for new anti-TB drug development.