Artículos de revistas: "Peptides Synthesis"

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Padalkar, Tanaji Dnyanadev. "Chemical Synthesis of Peptides". International Journal of Scientific Research 2, n.º 2 (1 de junio de 2012): 147–49. http://dx.doi.org/10.15373/22778179/feb2013/49.

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Kang, Taek Jin y Hiroaki Suga. "Ribosomal synthesis of nonstandard peptidesThis paper is one of a selection of papers published in this Special Issue, entitled CSBMCB — Systems and Chemical Biology, and has undergone the Journal's usual peer review process." Biochemistry and Cell Biology 86, n.º 2 (abril de 2008): 92–99. http://dx.doi.org/10.1139/o08-009.

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It is well known that standard peptides, which comprise proteinogenic amino acids, can act as specific chemical probes to target proteins with high affinity. Despite this fact, a number of peptide drug leads have been abandoned because of their poor cell permeability and protease instability. On the other hand, nonstandard peptides isolated as natural products often exhibit remarkable pharmaco-behavior and stability in vivo. Although it is likely that numerous nonstandard therapeutic peptides capable of recognizing various targets could have been synthesized, enzymes for nonribosomal peptide syntheses are complex; therefore, it is difficult to engineer such modular enzymes to build nonstandard peptide libraries. Here we describe an emerging technology for the synthesis of nonstandard peptides that employs an integrated system of reconstituted cell-free translation and flexizymes. We summarize the historical background of this technology and discuss its current and future applications to the synthesis of nonstandard peptides and drug discovery.

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Mourtas, Spyridon, Christina Katakalou, Dimitrios Gatos y Kleomenis Barlos. "Convergent Synthesis of Thioether Containing Peptides". Molecules 25, n.º 1 (5 de enero de 2020): 218. http://dx.doi.org/10.3390/molecules25010218.

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Thioether containing peptides were obtained following three synthetic routes. In route A, halo acids esterified on 2-chlorotrityl(Cltr) resin were reacted with N-fluorenylmethoxycarbonyl (Fmoc) aminothiols. These were either cleaved from the resin to the corresponding (Fmoc-aminothiol)carboxylic acids, which were used as key building blocks in solid phase peptide synthesis (SPPS), or the N-Fmoc group was deprotected and peptide chains were elongated by standard SPPS. The obtained N-Fmoc protected thioether containing peptides were then condensed either in solution, or on solid support, with the appropriate amino components of peptides. In route B, the thioether containing peptides were obtained by the reaction of N-Fmoc aminothiols with bromoacetylated peptides, which were synthesized on Cltr-resin, followed by removal of the N-Fmoc group and subsequent peptide elongation by standard SPPS. In route C, the thioether containing peptides were obtained by the condensation of a haloacylated peptide synthesized on Cltr-resin and a thiol-peptide synthesized either on 4-methoxytrityl(Mmt) or trityl(Trt) resin.

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Tanaka, Masayoshi, Shogo Saito, Reo Kita, Jaehee Jang, Yonghyun Choi, Jonghoon Choi y Mina Okochi. "Array-Based Screening of Silver Nanoparticle Mineralization Peptides". International Journal of Molecular Sciences 21, n.º 7 (30 de marzo de 2020): 2377. http://dx.doi.org/10.3390/ijms21072377.

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The use of biomolecules in nanomaterial synthesis has received increasing attention, because they can function as a medium to produce inorganic materials in ambient conditions. Short peptides are putative ligands that interact with metallic surfaces, as they have the potential to control the synthesis of nanoscale materials. Silver nanoparticle (AgNP) mineralization using peptides has been investigated; however, further comprehensive analysis must be carried out, because the design of peptide mediated-AgNP properties is still highly challenging. Herein, we employed an array comprising 200 spot synthesis-based peptides, which were previously isolated as gold nanoparticle (AuNP)-binding and/or mineralization peptides, and the AgNP mineralization activity of each peptide was broadly evaluated. Among 10 peptides showing the highest AgNP-synthesis activity (TOP10), nine showed the presence of EE and E[X]E (E: glutamic acid, and X: any amino acid), whereas none of these motifs were found in the WORST25 (25 peptides showing the lowest AgNP synthesis activity) peptides. The size and morphology of the particles synthesized by TOP3 peptides were dependent on their sequences. These results suggested not only that array-based techniques are effective for the peptide screening of AgNP mineralization, but also that AgNP mineralization regulated by peptides has the potential for the synthesis of AgNPs, with controlled morphology in environmentally friendly conditions.

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Liu, Xuejian, Robert B. P. Elmes y Katrina A. Jolliffe. "Synthesis of Side-Chain Modified Peptides Using Iterative Solid Phase ‘Click' Methodology". Australian Journal of Chemistry 70, n.º 2 (2017): 201. http://dx.doi.org/10.1071/ch16567.

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A series of side-chain modified peptides have been prepared via an iterative sequence of peptide couplings and azide–alkyne cycloadditions (‘click’ reactions) using Fmoc-solid phase peptide synthesis. This efficient modular synthetic route allows the systematic and sequential incorporation of a variety of side-chain modifications onto short peptides. The versatility of this approach was demonstrated by the synthesis of a series of short peptides with appended anion recognition motifs and fluorescent indicators.

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Perich, JW y RB Johns. "Synthesis of Casein-Related Peptides and Phosphopeptides. XV. The Efficient Synthesis of Multiple-Ser(P)-Containing Peptides". Australian Journal of Chemistry 44, n.º 12 (1991): 1683. http://dx.doi.org/10.1071/ch9911683.

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The synthesis of Ac-Ser(P)- NHMe and multiple-Ser(P)-containing peptides Ac-Ser(P)-Ser(P)-NHMe and Ac-Ser(P)-Ser(P)-Ser(P)- NHMe is described. The use of Boc -Ser(PO3Ph2)-OH in the Boc mode of peptide synthesis for the preparation of the protected Ser(PO3Ph2)-containing peptides was followed by platinum-mediated hydrogenolytic deprotection.

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Liu, Dan, Ya-Li Guo, Jin Qu y Chi Zhang. "Recyclable hypervalent-iodine-mediated solid-phase peptide synthesis and cyclic peptide synthesis". Beilstein Journal of Organic Chemistry 14 (22 de mayo de 2018): 1112–19. http://dx.doi.org/10.3762/bjoc.14.97.

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The system of the hypervalent iodine(III) reagent FPID and (4-MeOC6H4)3P was successfully applied to solid-phase peptide synthesis and cyclic peptide synthesis. Four peptides with biological activities were synthesized through SPPS and the bioactive cyclic heptapeptide pseudostellarin D was obtained via solution-phase peptide synthesis. It is worth noting that FPID can be readily regenerated after the peptide coupling reaction.

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Yano, Shinya, Toshihiro Mori y Hideki Kubota. "Silylated Tag-Assisted Peptide Synthesis: Continuous One-Pot Elongation for the Production of Difficult Peptides under Environmentally Friendly Conditions". Molecules 26, n.º 12 (8 de junio de 2021): 3497. http://dx.doi.org/10.3390/molecules26123497.

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Addition of the silylated tag (STag) enables peptides to be highly soluble in CPME, allowing them to be used at high concentrations in a coupling reaction to enhance reactivity and achieve effective synthesis of sterically hindered peptides. We described the development of a continuous one-pot STag-assisted peptide synthesis platform as a method that provides near-stoichiometric, speedy, environmentally friendly, and scalable peptide synthesis.

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Carmona, Adriana K., Maria Aparecida Juliano y Luiz Juliano. "The use of Fluorescence Resonance Energy Transfer (FRET) peptidesfor measurement of clinically important proteolytic enzymes". Anais da Academia Brasileira de Ciências 81, n.º 3 (septiembre de 2009): 381–92. http://dx.doi.org/10.1590/s0001-37652009000300005.

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Proteolytic enzymes have a fundamental role in many biological processes and are associated with multiple pathological conditions. Therefore, targeting these enzymes may be important for a better understanding of their function and development of therapeutic inhibitors. Fluorescence Resonance Energy Transfer (FRET) peptides are convenient tools for the study of peptidases specificity as they allow monitoring of the reaction on a continuous basis, providing a rapid method for the determination of enzymatic activity. Hydrolysis of a peptide bond between the donor/acceptor pair generates fluorescence that permits the measurement of the activity of nanomolar concentrations of the enzyme. The assays can be performed directly in a cuvette of the fluorimeter or adapted for determinations in a 96-well fluorescence plate reader. The synthesis of FRET peptides containing ortho-aminobenzoic acid (Abz) as fluorescent group and 2, 4-dinitrophenyl (Dnp) or N-(2, 4-dinitrophenyl)ethylenediamine (EDDnp) as quencher was optimized by our group and became an important line of research at the Department of Biophysics of the Federal University of São Paulo. Recently, Abz/Dnp FRET peptide libraries were developed allowing high-throughput screening of peptidases substrate specificity. This review presents the consolidation of our research activities undertaken between 1993 and 2008 on the synthesis of peptides and study of peptidases specificities.

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Li, Wenyi, John D. Wade, Eric Reynolds y Neil M. O'Brien-Simpson. "Chemical Modification of Cellulose Membranes for SPOT Synthesis". Australian Journal of Chemistry 73, n.º 3 (2020): 78. http://dx.doi.org/10.1071/ch19335.

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Since the development of solid-phase peptide synthesis in the 1960s, many laboratories have modified the technology for the production of peptide arrays to facilitate the discovery of novel peptide mimetics and therapeutics. One of these, known as SPOT synthesis, enables parallel peptide synthesis on cellulose paper sheets and has several advantages over other peptide arrays methods. Today, the SPOT technique remains one of the most frequently used methods for synthesis and screening of peptides on arrays. Although polypropylene and glass can be used for the preparation of peptide arrays, the most commonly used material for SPOT membranes is cellulose. Critical to the success of the SPOT synthesis is the ability to modify a cellulose membrane to make it more suitable for solid-phase peptide synthesis of peptides and their analogues. In this review, we highlight the current range of chemical modifications of cellulose that have been developed to enable SPOT synthesis and further enhance its impact on peptide drug discovery. This will contribute to further chemical modifications and applications of SPOT synthesis for peptide arrays and peptide therapeutic screening.

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Ovchinnikov, Mikhail V., Zhanna D. Bespalova, Aleksandr S. Molokoedov, Inna V. Revenko, Nikolai F. Sepetov, Olga L. Isakova y Mikhail I. Titov. "Atriopeptins. II. Synthesis of N-terminal fragments". Collection of Czechoslovak Chemical Communications 54, n.º 3 (1989): 784–95. http://dx.doi.org/10.1135/cccc19890784.

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Peptides, corresponding to the N-terminal sequence in atriopeptins, were synthesized by classical methods of peptide chemistry in solution. The obtained peptides were characterized by various physicochemical methods. The scheme and methods of the synthesis are discussed.

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Racheva, M., O. Romero, K. K. Julich-Gruner, A. S. Ulrich, C. Wischke y A. Lendlein. "Purity of mushroom tyrosinase as a biocatalyst for biomaterial synthesis affects the stability of therapeutic peptides". MRS Proceedings 1718 (2015): 85–90. http://dx.doi.org/10.1557/opl.2015.260.

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ABSTRACTThe formation of injectable implants in the presence of cells or solutes has previously been conceptualized to be based on the selectivity of bioorthogonal chemical reactions. As an alternative approach, hydrogel network synthesis by enzymatic reactions with a typically high inherent substrate specificity and low toxicity have been repeatedly proposed, e.g. using commercial mushroom tyrosinase (MTyr), which specifically catalyzes phenol oxidation. In this study, it should be explored whether MTyr is compatible with therapeutic peptides that may be delivered from such hydrogels in the future. Based on the specificity of MTyr to phenol residues, no modification of peptides lacking the amino acid tyrosine would be expected. One example of such peptides is gramicidin S (GS), a potent antimicrobial peptide. However, when GS was incubated with commercial MTyr, peptide degradation occurred as observed by HPLC analysis. Several fragments of the peptide were detected by MALDI-TOF. Contamination of MTyr with peptidases was proven as the source of undesired peptide cleavage, which needs to be considered when preparing enzymatically crosslinked hydrogels for biomedical applications.

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Chun, Candy K. Y. y Richard J. Payne. "Synthesis of MUC1 Peptide and Glycopeptide Dendrimers". Australian Journal of Chemistry 62, n.º 10 (2009): 1339. http://dx.doi.org/10.1071/ch09282.

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Several dendrimers possessing multiple copies of peptides and glycopeptides belonging to the MUC1 eicosapeptide tandem repeat sequence have been prepared. Fmoc-strategy solid-phase peptide synthesis was used to construct the peptides and glycopeptides, which were conjugated to suitably functionalized dendrimer cores using the copper-catalyzed azide-alkyne cycloaddition reaction to produce multivalent peptide and glycopeptide dendrimers.

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Abdel Malak, C. A. "Calf chymosin as a catalyst of peptide synthesis". Biochemical Journal 288, n.º 3 (15 de diciembre de 1992): 941–43. http://dx.doi.org/10.1042/bj2880941.

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Calf chymosin was shown to catalyse peptide synthesis optimally over the range pH 4-5, giving satisfactory yields of methyl esters or p-nitroanilides of benzyloxycarbonyl tetra- to hexa-peptides, provided that hydrophobic amino-acid residues form the new peptide bonds. The effectiveness of the enzyme depends also on the nature of adjacent amino-acid residues. As an aspartate-proteinase with a characteristic specificity pattern chymosin would be useful for the synthesis of middle-length peptides.

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Niquille, David L., Douglas A. Hansen y Donald Hilvert. "Reprogramming Nonribosomal Peptide Synthesis by Surgical Mutation". Synlett 30, n.º 19 (28 de octubre de 2019): 2123–30. http://dx.doi.org/10.1055/s-0039-1690711.

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Nonribosomal peptide synthetases produce highly modified bioactive peptides, many of which are used therapeutically. As such, they have been the target of intense protein engineering to enable biosynthetic access to peptide variants with improved drug properties or altered bioactivities. In this account, we describe our ongoing efforts to reprogram nonribosomal peptide synthesis by surgical mutation. In contrast to ribosomal biosynthesis, nonribosomal peptide synthesis has proven difficult to engineer, arguably due to a lack of suitable tools. To address this limitation, we have established a high-throughput assay that provides unprecedented control over the gatekeeper adenylation domains responsible for building block selection and incorporation. Expansion of this strategy to other building blocks and domains promises to make it a powerful evolutionary platform for tailoring assembly lines for custom synthesis of peptide therapeutics.1. Nonribosomal Peptides2. Reprogramming A Domains for Clickable Amino Acids3 A High-Throughput A Domain Assay4 Reprogramming A Domains for β-Amino Acids5 Downstream Processing6 Conclusions and Outlook

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Castro, Aaron, Evelyna Derhovanessian, Ulrich Luxemburger, Michaela Beck, Franziska Gehring, Holger Wenschuh, Johannes Zerweck, Florian Kern, Ulf Reimer y Ugur Sahin. "A Fast, Flexible and Low Cost Process for Neo-Epitope Based Immune Monitoring". Journal of Immunology 198, n.º 1_Supplement (1 de mayo de 2017): 213.5. http://dx.doi.org/10.4049/jimmunol.198.supp.213.5.

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Abstract Advances in genomic technologies have paved the way to developing personalized cancer vaccines targeting neo-antigens. Patient-specific vaccines, targeting several neo-antigens in one go have already entered the clinic. Such personalized, multi-target approach poses a challenge for immune monitoring of vaccine-specific T-cell responses in a fast, flexible and cost-effective fashion. Most immune monitoring protocols use 9–15-mer synthetic peptides originating from the vaccine target antigen. In contrast to detection of shared antigen-specific T-cells, for which the same peptide batch can be used for several patients, immune monitoring of individual neo-antigen-specific T-cell responses requires small amounts of large numbers of peptides (e.g. 40 × 15-mer peptides for 10 neo-epitopes of 27 amino-acids), which can only be used for one single patient. Therefore, standard peptide synthesis approaches applying commercial peptide synthesizers not only lack required throughput and speed but also generate peptides at prohibitive costs. Here, we present data demonstrating the flexible application of our high-throughput, low cost FastTrack peptide synthesis approach in comparison with different specifications of standard peptides in ex-vivo ELISPOT to monitor neo-antigen specific immune responses in patients participating in the IVAC MUTANOME Phase I clinical trial (NCT02035956). Application of the new peptide synthesis method enables the assembly of up to 1200 peptides in less than 3 weeks at appr. 20% of standard synthesis costs.

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Naider, Fred R. y Jeffrey M. Becker. "Synthesis of prenylated peptides and peptide esters". Biopolymers 43, n.º 1 (1997): 3–14. http://dx.doi.org/10.1002/(sici)1097-0282(1997)43:1<3::aid-bip2>3.0.co;2-z.

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Schiefelbein, Kevin y Nina Hartrampf. "Flow-based Methods in Chemical Peptide and Protein Synthesis". CHIMIA International Journal for Chemistry 75, n.º 6 (30 de junio de 2021): 480–83. http://dx.doi.org/10.2533/chimia.2021.480.

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Flow chemistry has emerged as a powerful method for on-demand chemical synthesis and modification of peptides and proteins. Herein, we discuss the characteristics of flow chemistry and how they are applied to various aspects of peptide chemistry. We highlight recent advances in automated flow-based peptide synthesis, which extend the length of peptides routinely accessible to single-domain proteins and allow for the collection of time-resolved synthesis data. Applications of this data for the prediction of synthesis outcome and the potential for the development of more sustainable synthesis methods are also discussed. Finally, we will review solutionphase approaches, including flow-based ligation strategies and peptide cyclization. Throughout this review, the current challenges and potential future developments are highlighted.

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Ribeiro, Ana R. M., Helena P. Felgueiras, Susana P. G. Costa y Sílvia M. M. A. Pereira-Lima. "Synthesis of Peptaibolin, an Antimicrobial Peptide". Proceedings 78, n.º 1 (1 de diciembre de 2020): 47. http://dx.doi.org/10.3390/iecp2020-08654.

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To tackle one of the biggest global health problems, the resistance of microorganisms to antibiotics, a collective effort in the search for more effective agents against bacteria was required. Peptides with antimicrobial activity have been raising much attention as a promising alternative for antibiotics. Peptaibols, for instance, are a family of antimicrobial peptides (AMPs) with great biomedical potential, in which the Peptaibolin can be highlighted. This peptide has gained relevance due to its small amino acids content, only four, and its acetyl group and a phenylalaninol residue (Phol) at the N-terminal and C-terminal, respectively. Here, we report the synthesis of Peptaibolin through Solid Phase Peptide Synthesis assisted by Microwave heating (MW-SPPS) in a pre-loaded Phe-Wang resin. Starting from a loading of 0.51 mmol/g, two syntheses were made, using two different combinations of coupling reagents. The best option was DIC/Oxima, achieving a yield of 50.0%. Proton Nuclear Magnetic Resonance (1H-NMR) studies confirmed the peptide structure, while High Performance Liquid Chromatography (HPLC) verified the peptide purity. The peptide solubility was examined against several combinations of solvents. Peptaibolin was not soluble in water, only in organic solvents or in the combination of both. Antimicrobial testing was conducted using Staphylococcus aureus, Staphylococcus epidermidis, Escherichia coli, and Pseudomonas aeruginosa. Minimum inhibitory concentration studies demonstrated the resistance of bacteria to the peptide action and the peptide instability in bacterial growth conditions.

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Mäde, Veronika, Sylvia Els-Heindl y Annette G. Beck-Sickinger. "Automated solid-phase peptide synthesis to obtain therapeutic peptides". Beilstein Journal of Organic Chemistry 10 (22 de mayo de 2014): 1197–212. http://dx.doi.org/10.3762/bjoc.10.118.

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The great versatility and the inherent high affinities of peptides for their respective targets have led to tremendous progress for therapeutic applications in the last years. In order to increase the drugability of these frequently unstable and rapidly cleared molecules, chemical modifications are of great interest. Automated solid-phase peptide synthesis (SPPS) offers a suitable technology to produce chemically engineered peptides. This review concentrates on the application of SPPS by Fmoc/t-Bu protecting-group strategy, which is most commonly used. Critical issues and suggestions for the synthesis are covered. The development of automated methods from conventional to essentially improved microwave-assisted instruments is discussed. In order to improve pharmacokinetic properties of peptides, lipidation and PEGylation are described as covalent conjugation methods, which can be applied by a combination of automated and manual synthesis approaches. The synthesis and application of SPPS is described for neuropeptide Y receptor analogs as an example for bioactive hormones. The applied strategies represent innovative and potent methods for the development of novel peptide drug candidates that can be manufactured with optimized automated synthesis technologies.

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Hayes, Maria, Leticia Mora y Simona Lucakova. "Identification of Bioactive Peptides from Nannochloropsis oculata Using a Combination of Enzymatic Treatment, in Silico Analysis and Chemical Synthesis". Biomolecules 12, n.º 12 (2 de diciembre de 2022): 1806. http://dx.doi.org/10.3390/biom12121806.

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In vitro ACE-1 inhibitory peptides were characterised previously from a number of microalgal species including Spirulina platensis (peptide IAPG), Chlorella vulgaris (peptides FDL, AFL, VVPPA), Isochrysis galbana (peptide YMGLDLK), Chlorella sorokiniana (peptides IW and LW) and indeed Nannochloropsis oculata (peptides GMNNLTP and LEQ). The isolation of protein from Nannochloropsis oculata using a combination of ammonium salt precipitation and xylanase treatment of resulting biomass combined with molecular weight cut off filtration to produce a permeate and characterisation of bioactive peptides is described. The Angiotensin-1-converting enzyme (ACE-1) IC50 value for the generated permeate fraction was 370 µg/mL. Ninety-five peptide sequences within the permeate fraction were determined using mass spectrometry and eight peptides were selected for chemical synthesis based on in silico analysis. Synthesized peptides were novel based on a search of the literature and relevant databases. In silico, simulated gastrointestinal digestion identified further peptides with bioactivities including ACE-1 inhibitory peptides and peptides with antithrombotic and calcium/calmodulin-dependent kinase II (CAMKII) inhibition. This work highlights the potential of Nannochloropsis oculata biomass as both a protein and bioactive peptide resource, which could be harnessed for use in the development of functional foods and feeds.

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Perich, JW y RB Johns. "Synthesis of Casein-Related Peptides and Phosphopeptides. XII. The Synthesis of O-Phosphoseryl-Containing Peptides With Site-Specific Serine Residues". Australian Journal of Chemistry 44, n.º 3 (1991): 405. http://dx.doi.org/10.1071/ch9910405.

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The synthesis of the two Ser/Ser(P)-containing peptides H-Ser-Ser(P)-Ser(P)-NHMe.CF3CO2H and H-Ser(P)-Ser-Ser(P)-NHMe.CF3CO2H is described. The selective use of Boc-Ser(PO3Ph2)-OH and Boc -Ser( Bzl )-OH in the Boc mode of peptide synthesis for the preparation of the protected Ser( Bzl )/Ser(PO3Ph2)-containing peptides is followed by platinum-mediated hydrogenolytic cleavage of the benzyl ether and phenyl phosphate groups.

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Hou, Wen, Lei Liu, Xiaohong Zhang y Chuanfa Liu. "A new method of N to C sequential ligation using thioacid capture ligation and native chemical ligation". Royal Society Open Science 5, n.º 6 (junio de 2018): 172455. http://dx.doi.org/10.1098/rsos.172455.

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Sequential peptide ligation strategy becomes more and more important in large protein or long peptides chemical synthesis due to the limited peptide/protein size obtained by solid phase synthesis of individual peptides or even one-step peptide ligation. Herein, we developed an alternative method which could perform the sequential peptide ligation of several segments from N to C direction based on the combined use of thioacid capture ligation and native chemical ligation. The sweet protein monellin was produced through this strategy on a scale of multi-milligrams.

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Shi, Yu, Chunwu Yu y Wentao Ma. "Towards an RNA/Peptides World by the Direct RNA Template Mechanism: The Emergence of Membrane-Stabilizing Peptides in RNA-Based Protocells". Life 13, n.º 2 (14 de febrero de 2023): 523. http://dx.doi.org/10.3390/life13020523.

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How functional peptides may have arisen is a significant problem for the scenario of the RNA world. An attractive idea, the direct RNA template (DRT) hypothesis, proposes that RNA molecules can bind amino acids specifically and promote the synthesis of corresponding peptides, thereby starting the RNA/peptides world. To investigate the plausibility of this idea, we modeled the emergence of a “membrane-stabilizing peptide” in RNA-based protocells—such a peptide was suggested to have appeared early in the RNA world based on experimental evidence. The computer simulation demonstrated that the protocells containing the “RNA gene” encoding this peptide may spread in the system owing to the peptide’s function. The RNA gene may either originate de novo in protocells or emerge in protocells already containing ribozymes—here we adopt a nucleotide synthetase ribozyme as an example. Furthermore, interestingly, we show that a “nucleotide synthetase peptide” encoded by RNA (also via the DRT mechanism) may substitute the nucleotide synthetase ribozyme in evolution, which may represent how “functional-takeover” in the RNA world could have occurred. Overall, we conclude that the transition from the RNA world towards an RNA/peptides world may well have been mediated by the DRT mechanism. Remarkably, the successful modeling on the emergence of membrane-stabilizing peptide in RNA-based protocells is per se significant, which may imply a “promising” way for peptides to enter the RNA world, especially considering the weak interaction between RNA and the membrane in chemistry.

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Lin, Rongcan, Yueqiao Wang, Xin Li, Yan Liu y Yufen Zhao. "pH-Dependent Adsorption of Peptides on Montmorillonite for Resisting UV Irradiation". Life 10, n.º 4 (20 de abril de 2020): 45. http://dx.doi.org/10.3390/life10040045.

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Ultraviolet (UV) irradiation is considered an energy source for the prebiotic chemical synthesis of life’s building blocks. However, it also results in photodegradation of biology-related organic compounds on early Earth. Thus, it is important to find a process to protect these compounds from decomposition by UV irradiation. Herein, pH effects on both the adsorption of peptides on montmorillonite (MMT) and the abilities of peptides to resist UV irradiation due to this adsorption were systematically studied. We found that montmorillonite (MMT) can adsorb peptides effectively under acidic conditions, while MMT-adsorbed peptides can be released under basic conditions. Peptide adsorption is positively correlated with the length of the peptide chains. MMT’s adsorption of peptides and MMT-adsorbed peptide desorption are both rapid-equilibrium, and it takes less than 30 min to reach the equilibrium in both cases. Furthermore, compared to free peptides, MMT-adsorbed peptides under acidic conditions are well protected from UV degradation even after prolonged irradiation. These results indicate amino acid/peptides are able to concentrate from aqueous solution by MMT adsorption under low-pH conditions (concentration step). The MMT-adsorbed peptides survive under UV irradiation among other unprotected species (storage step). Then, the MMT-adsorbed peptides can be released to the aqueous solution if the environment becomes more basic (releasing step), and these free peptides are ready for polymerization to polypeptides. Hence, a plausible prebiotic concentration–storage–release cycle of amino acids/peptides for further polypeptide synthesis is established.

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Susanto, Edy, Anik Fadlilah y Muhammad Fathul Amin. "Synthesis, extraction and idetification of meat bioactive peptides: a review". IOP Conference Series: Earth and Environmental Science 888, n.º 1 (1 de noviembre de 2021): 012058. http://dx.doi.org/10.1088/1755-1315/888/1/012058.

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Abstract The consumption of meat should consider the concept of functional food. The meat had a highquality protein and contain of bioactive peptide compounds. Amino acid was component of bioactive peptides compound. It joined by covalent bonds known as amide or peptide bonds. A lot of research was currently focused on the bioactive peptide compounds isolated from myofibril and sarcoplasmic proteins with the synthesis, extraction, and identification methods. This study used a systematic review to get the structure of amino acids that the source of bioactive components and the principle of synthesis, extraction and identification of bioactive peptide in the meat. This paper highlights were finding on the structure of amino acid in the meat. The proportion of amino acids was also different in each animal body location. The result identified that more than 170 peptides were released from the main structure of the myofibril (actin, myosin) and sarcoplasmic muscle proteins, and the synthesis, extraction and bioactive peptide identification in the meat as well as their potential use as functional food.

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Northfield, Susan E., Simon J. Mountford, Jerome Wielens, Mengjie Liu, Lei Zhang, Herbert Herzog, Nicholas D. Holliday et al. "Propargyloxyproline Regio- and Stereoisomers for Click-Conjugation of Peptides: Synthesis and Application in Linear and Cyclic Peptides". Australian Journal of Chemistry 68, n.º 9 (2015): 1365. http://dx.doi.org/10.1071/ch15146.

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The use of the click reaction for the introduction of conjugate groups, such as affinity or fluorescent labels, to a peptide for the study of peptide biochemistry and pharmacology is widespread. However, the nature and location of substituted 1,2,3-triazoles in peptide sequences may markedly affect conformation or binding as compared with native sequences. We have examined the preparation and application of propargyloxyproline (Pop) residues as a precursor to such peptide conjugates. Pop residues are available in a range of regio- and stereoisomers from hydroxyproline precursors and are readily prepared in Fmoc-protected form. They can be incorporated routinely in peptide synthesis and broadly retain the conformational properties of the parent proline containing peptides. This is exemplified by the preparation of biotin- and fluorophore-labelled peptides derived from linear and cyclic peptides.

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Wu, Jianbin, Guanghui An, Siqi Lin, Jianbo Xie, Wei Zhou, Hao Sun, Yi Pan y Guigen Li. "Solution-phase-peptide synthesis via the group-assisted purification (GAP) chemistry without using chromatography and recrystallization". Chem. Commun. 50, n.º 10 (2014): 1259–61. http://dx.doi.org/10.1039/c3cc48509a.

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The solution phase synthesis of N-protected amino acids and peptides has been achieved through GAP chemistry by avoiding disadvantages of the solid-phase-peptide synthesis (SPPS) and liquid-phase-peptide synthesis. The environmentally friendly GAP synthesis can substantially reduce the use of solvents, silica gels, energy and manpower.

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Foden, Callum S., Saidul Islam, Christian Fernández-García, Leonardo Maugeri, Tom D. Sheppard y Matthew W. Powner. "Prebiotic synthesis of cysteine peptides that catalyze peptide ligation in neutral water". Science 370, n.º 6518 (12 de noviembre de 2020): 865–69. http://dx.doi.org/10.1126/science.abd5680.

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Peptide biosynthesis is performed by ribosomes and several other classes of enzymes, but a simple chemical synthesis may have created the first peptides at the origins of life. α-Aminonitriles—prebiotic α–amino acid precursors—are generally produced by Strecker reactions. However, cysteine’s aminothiol is incompatible with nitriles. Consequently, cysteine nitrile is not stable, and cysteine has been proposed to be a product of evolution, not prebiotic chemistry. We now report a high-yielding, prebiotic synthesis of cysteine peptides. Our biomimetic pathway converts serine to cysteine by nitrile-activated dehydroalanine synthesis. We also demonstrate that N-acylcysteines catalyze peptide ligation, directly coupling kinetically stable—but energy-rich—α-amidonitriles to proteinogenic amines. This rare example of selective and efficient organocatalysis in water implicates cysteine as both catalyst and precursor in prebiotic peptide synthesis.

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30

Hlaváček, Jan, Otto Smékal, Jan Pospíšek y Tomislav Barth. "Synthesis of Peptides Influencing Growth Hormone Release". Collection of Czechoslovak Chemical Communications 59, n.º 3 (1994): 707–17. http://dx.doi.org/10.1135/cccc19940707.

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A solid phase peptide synthesis of 17 growth hormone (GH) releasing peptide analogues Ia - IIIc for their use in a pharmacological assay on GH release is described. While the linear peptide amides Ia - Ij were synthesized on p-methylbenzhydrylamine resin using Boc strategy, and cleaved by HF in the presence of scavengers the linear peptide amides Ik and Il were prepared on Merrifield benzyl ester type resin using Fmoc strategy and cleaved by ammonolysis. The deleted peptide amides IIa and IIb were obtained as by-products during HPLC purification of analogues Ic and Id. The linear precursors of cyclic peptides IIIa - IIIc were also prepared on Merrifield resin and cleaved under mild alkaline conditions. Their cyclization was performed in solution by diphenylphosphoryl azide.

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31

Khavinson, V. Kh. "Peptide medicines: past, present, future". Clinical Medicine (Russian Journal) 98, n.º 3 (16 de julio de 2020): 165–77. http://dx.doi.org/10.30629/0023-2149-2020-98-3-165-177.

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This review provides research data on drugs made on the basis of polypeptides isolated from different animal organs. They initiated the development of drugs of a peptide origin. Besides, a group of pharmaceuticals (peptide complexes), created at the Military Medical Academy named after S.M. Kirov (Thymalin, Epithalamin, Cortexin, Prostatilen, Retinalamin) under the supervision of V.Kh. Khavinson in the 80–90-ies of the 20th century has been described. At present, pharmacologists focus on isolation of short di-, tri-, tetrapeptides, identification of their primary structures and subsequent synthesis from amino acids (Thymogen, Vilon, Pinealon, Vesugen, Epitalon, Bronchogen, Cardiogen, etc.). The results of cutting edge investigations of peptide influence on various functions of an organism, gene expression and protein synthesis have been presented. A molecular mechanism of a peptide-DNA interaction has been depicted. Short peptides have been revealed to regulate gene expression, protein synthesis, chromatin state and promote telomeres elongation. Peptides regulate targeted differentiation of pluripotent cells and decrease their replicative ageing. Animals administered with peptides showed a decreased tumor incidence, normalized melatonin level and an increased average life span. To summarize the above, it is worth noting further prospects of studies aimed at creation of novel drugs on the basis of short peptides with targeted regulation of certain gene groups and protein synthesis which underlies the development of pharmacogenomics as fundamentals for future therapy.

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32

BODANSZKY, MIKLOS. "Synthesis of Vasoactive Intestinal Peptide and Related Peptides". Annals of the New York Academy of Sciences 527, n.º 1 Vasoactive In (junio de 1988): 20–28. http://dx.doi.org/10.1111/j.1749-6632.1988.tb26969.x.

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33

Stærkær, Gunnar, Mogens H. Jakobsen, Carl Erik Olsen y Arne Holmb. "Solid phase peptide synthesis of selectively phosphorylated peptides." Tetrahedron Letters 32, n.º 39 (septiembre de 1991): 5389–92. http://dx.doi.org/10.1016/s0040-4039(00)92394-3.

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34

Wang, Wei, S. Cyrus Khojasteh y Dian Su. "Biosynthetic Strategies for Macrocyclic Peptides". Molecules 26, n.º 11 (1 de junio de 2021): 3338. http://dx.doi.org/10.3390/molecules26113338.

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Macrocyclic peptides are predominantly peptide structures bearing one or more rings and spanning multiple amino acid residues. Macrocyclization has become a common approach for improving the pharmacological properties and bioactivity of peptides. A variety of ribosomal-derived and non-ribosomal synthesized cyclization approaches have been established. The biosynthesis of backbone macrocyclic peptides using seven new emerging methodologies will be discussed with regard to the features and strengths of each platform rather than medicinal chemistry tools. The mRNA display variant, known as the random nonstandard peptide integrated discovery (RaPID) platform, utilizes flexible in vitro translation (FIT) to access macrocyclic peptides containing nonproteinogenic amino acids (NAAs). As a new discovery approach, the ribosomally synthesized and post-translationally modified peptides (RiPPs) method involves the combination of ribosomal synthesis and the phage screening platform together with macrocyclization chemistries to generate libraries of macrocyclic peptides. Meanwhile, the split-intein circular ligation of peptides and proteins (SICLOPPS) approach relies on the in vivo production of macrocyclic peptides. In vitro and in vivo peptide library screening is discussed as an advanced strategy for cyclic peptide selection. Specifically, biosynthetic bicyclic peptides are highlighted as versatile and attractive modalities. Bicyclic peptides represent another type of promising therapeutics that allow for building blocks with a heterotrimeric conjugate to address intractable challenges and enable multimer complexes via linkers. Additionally, we discuss the cell-free chemoenzymatic synthesis of macrocyclic peptides with a non-ribosomal catalase known as the non-ribosomal synthetase (NRPS) and chemo-enzymatic approach, with recombinant thioesterase (TE) domains. Novel insights into the use of peptide library tools, activity-based two-hybrid screening, structure diversification, inclusion of NAAs, combinatorial libraries, expanding the toolbox for macrocyclic peptides, bicyclic peptides, chemoenzymatic strategies, and future perspectives are presented. This review highlights the broad spectrum of strategy classes, novel platforms, structure diversity, chemical space, and functionalities of macrocyclic peptides enabled by emerging biosynthetic platforms to achieve bioactivity and for therapeutic purposes.

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35

Roice, M. y V. N. Rajasekharan Pillai. "Preparation of protected peptides by gel-phase synthesis on butanediol dimethacrylate cross-linked polystyrene support". Protein & Peptide Letters 7, n.º 6 (diciembre de 2000): 365–72. http://dx.doi.org/10.2174/092986650706221207161246.

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Abstract: Preparation of fully protected peptide C-terminal esters in high yield and purity by making use of gel-phase synthesis on chloromethyl butanediol dimethacrylate (BDODMA) crosslinked polystyrene is described. The C-terminal amino acid of the peptide was incorporated by cesium salt method and the step-wise synthesis was carried out using HOBt active ester coupling procedure. The protected peptides were cleaved from the support by trans-esterification. The crude peptides were purified by HPLC and characterized by amino acid analysis, tic and MALDI TOF MS.

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36

Sajapin, Johann y Michael Hellwig. "Studies on the synthesis and stability of α-ketoacyl peptides". Amino Acids 52, n.º 10 (octubre de 2020): 1425–38. http://dx.doi.org/10.1007/s00726-020-02902-8.

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Abstract Oxidative stress, an excess of reactive oxygen species (ROS), may lead to oxidative post-translational modifications of proteins resulting in the cleavage of the peptide backbone, known as α-amidation, and formation of fragments such as peptide amides and α-ketoacyl peptides (α-KaP). In this study, we first compared different approaches for the synthesis of different model α-KaP and then investigated their stability compared to the corresponding unmodified peptides. The stability of peptides was studied at room temperature or at temperatures relevant for food processing (100 °C for cooking and 150 °C as a simulation of roasting) in water, in 1% (m/v) acetic acid or as the dry substance (to simulate the thermal treatment of dehydration processes) by HPLC analysis. Oxidation of peptides by 2,5-di-tert-butyl-1,4-benzoquinone (DTBBQ) proved to be the most suited method for synthesis of α-KaPs. The acyl side chain of the carbonyl-terminal α-keto acid has a crucial impact on the stability of α-KaPs. This carbonyl group has a catalytic effect on the hydrolysis of the neighboring peptide bond, leading to the release of α-keto acids. Unmodified peptides were significantly more stable than the corresponding α-KaPs. The possibility of further degradation reactions was shown by the formation of Schiff bases from glyoxylic or pyruvic acids with glycine and proven through detection of transamination products and Strecker aldehydes of α-keto acids by HPLC–MS/MS. We propose here a mechanism for the decomposition of α-ketoacyl peptides.

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37

Vivenzio, Giovanni, Maria Carmina Scala, Pasquale Marino, Michele Manfra, Pietro Campiglia y Marina Sala. "Dipropyleneglycol Dimethylether, New Green Solvent for Solid-Phase Peptide Synthesis: Further Challenges to Improve Sustainability in the Development of Therapeutic Peptides". Pharmaceutics 15, n.º 6 (20 de junio de 2023): 1773. http://dx.doi.org/10.3390/pharmaceutics15061773.

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In recent years, peptides have gained more success as therapeutic compounds. Nowadays, the preferred method to obtain peptides is solid-phase peptide synthesis (SPPS), which does not respect the principles of green chemistry due to the large number of toxic reagents and solvents used. The aim of this work was to research and study an environmentally sustainable solvent able to replace dimethylformamide (DMF) in fluorenyl methoxycarbonyl (Fmoc) solid-phase peptide synthesis. Herein, we report the use of dipropyleneglycol dimethylether (DMM), a well-known green solvent with low human toxicity following oral, inhalant, and dermal exposure and that is easily biodegradable. Some tests were needed to evaluate its applicability to all the steps of SPPS, such as amino acid solubility, resin swelling, deprotection kinetics, and coupling tests. Once the best green protocol was established, it was applied to the synthesis of different length peptides to study some of the fundamental parameters of green chemistry, such as PMI (process mass intensity) and the recycling of solvent. It was revealed that DMM is a valuable alternative to DMF in all steps of solid-phase peptide synthesis.

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38

Zheng, Mengjun, Ruina Wang, Si Chen, Yan Zou, Lan Yan, Linjing Zhao y Xiang Li. "Design, Synthesis and Antifungal Activity of Stapled Aurein1.2 Peptides". Antibiotics 10, n.º 8 (9 de agosto de 2021): 956. http://dx.doi.org/10.3390/antibiotics10080956.

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Aurein1.2 is a 13-residue antimicrobial peptide secreted by the Australian tree frog Litoria aurea. In order to improve its stabilities, the helical contents and corresponding biological activities of Aurein1.2 (a series of stapled analogues) were synthesized, and their potential antifungal activities were evaluated. Not surprisingly, the stapled Aurein1.2 peptides showed higher proteolytic stability and helicity than the linear counterpart. The minimum inhibitory concentration (MIC) of ten stapled peptides against six strains of common pathogenic fungi was determined by the microscale broth dilution method recommended by CLSI. Of them, Sau-1, Sau-2, Sau-5, and Sau-9 exhibited better inhibitory effects on the fungi than the linear peptide. These stapled Aurein1.2 peptides may serve as the leading compounds for further optimization and antifungal therapy.

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39

Eichler, Jutta y Richard A. Houghten. "Synthesis of cyclic disulfide peptides: comparison of oxidation methods". Protein & Peptide Letters 4, n.º 3 (junio de 1997): 157–64. http://dx.doi.org/10.2174/092986650403221017100014.

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Abstract: Seven cyclic disulfide peptides (oxytocin, salmon calcitonin 1-10, CTP, crustacean cardioactive peptide, somatostatin 3-14, [C2•6]-P-endorphin 1-6 and endothelin-P 3-11) were synthesized on soli<:1 phase and cyclized either on the resin, simultaneously with the cleavage from the resin, or in solution after cleavage, using eight different oxidation methods. The purities of the crude peptides were compared in order to evaluate the efficacy of the different oxidation methods with respect to the peptide sequences.

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40

Peng, Zhenghong. "NMR conformational analysis on cyclic decapeptide template molecule". Canadian Journal of Chemistry 77, n.º 8 (1 de agosto de 1999): 1394–404. http://dx.doi.org/10.1139/v99-128.

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We report the synthesis and conformational analysis of a series of cyclic and bicyclic decapeptide templates for combinatorial chemistry. The peptides were synthesized via solid phase synthesis and followed by solution cyclization. The conformation of the peptides was studied by proton NMR spectroscopy in DMSO and in TFE-water. The structure of the peptide template was calculated with the program DIANA and followed by SA from the NMR experimental constraints. The peptide adopts a fold comprising two β-strands and two type II β-turns. The design of such a restained cyclic decapeptide template will be discussed along with Template Assembled Synthetic Proteins (TASP).Key words: solid phase peptide synthesis, cyclic decapeptide, NMR, conformational analysis, β-sheet.

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41

Maeda, Kentaro, Yu-ichi Kiniwa, Yasufumi Ohfune, Shinichi Ishiguro, Koichi Suzuki, Kazuya Murata, Hideaki Matsuda y Tetsuro Shinada. "Solid phase synthesis of α-amino squaric acid-containing peptides". RSC Adv. 4, n.º 92 (2014): 50639–43. http://dx.doi.org/10.1039/c4ra10442k.

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A new method has been developed for the synthesis of 3-(1-aminoalkyl)-4-hydroxycyclobut-3-ene-1,2-dione [(α-amino squaric acid (α-Asq)]-containing peptides using solid phase peptide synthesis according to an Fmoc protecting group strategy.

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42

Graf, Michael, Mario Mardirossian, Fabian Nguyen, A. Carolin Seefeldt, Gilles Guichard, Marco Scocchi, C. Axel Innis y Daniel N. Wilson. "Proline-rich antimicrobial peptides targeting protein synthesis". Natural Product Reports 34, n.º 7 (2017): 702–11. http://dx.doi.org/10.1039/c7np00020k.

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Proline-rich antimicrobial peptides (PrAMPs) bind within the exit tunnel of the ribosome and inhibit translation elongation. Structures of ribosome-bound PrAMPs reveal the interactions with ribosomal components and could pave the way for the development of novel peptide-based antimicrobial agents.

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43

Li, Wenyi, Neil M. O'Brien-Simpson, Mohammed Akhter Hossain y John D. Wade. "The 9-Fluorenylmethoxycarbonyl (Fmoc) Group in Chemical Peptide Synthesis – Its Past, Present, and Future". Australian Journal of Chemistry 73, n.º 4 (2020): 271. http://dx.doi.org/10.1071/ch19427.

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The chemical formation of the peptide bond has long fascinated and challenged organic chemists. It requires not only the activation of the carboxyl group of an amino acid but also the protection of the Nα-amino group. The more than a century of continuous development of ever-improved protecting group chemistry has been married to dramatic advances in the chemical synthesis of peptides that, itself, was substantially enhanced by the development of solid-phase peptide synthesis by R. B. Merrifield in the 1960s. While the latter technology has continued to undergo further refinement and improvement in both its chemistry and automation, the development of the base-labile 9-fluorenylmethoxycarbonyl (Fmoc) group and its integration into current synthesis methods is considered a major landmark in the history of the chemical synthesis of peptides. The many beneficial attributes of the Fmoc group, which have yet to be surpassed by any other Nα-protecting group, allow very rapid and highly efficient synthesis of peptides, including ones of significant size and complexity, making it an even more valuable resource for research in the post-genomic world. This review charts the development and use of this Nα-protecting group and its adaptation to address the need for more green chemical peptide synthesis processes.

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44

Silva, Rúben D. M., João Franco Machado, Kyle Gonçalves, Francisco M. Lucas, Salete Batista, Rita Melo, Tânia S. Morais y João D. G. Correia. "Ultrasonication Improves Solid Phase Synthesis of Peptides Specific for Fibroblast Growth Factor Receptor and for the Protein-Protein Interface RANK-TRAF6". Molecules 26, n.º 23 (3 de diciembre de 2021): 7349. http://dx.doi.org/10.3390/molecules26237349.

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Considering our interest in the use of peptides as potential target-specific drugs or as delivery vectors of metallodrugs for various biomedical applications, it is crucial to explore improved synthetic methodologies to accomplish the highest peptide crude purity in the shortest time possible. Therefore, we compared “classical” fluorenylmethoxycarbonyl (Fmoc)-solid phase peptide synthesis (SPPS) with ultrasound(US)-assisted SPPS based on the preparation of three peptides, namely the fibroblast growth factor receptor 3(FGFR3)-specific peptide Pep1 (VSPPLTLGQLLS-NH2) and the novel peptides Pep2 (RQMATADEA-NH2) and Pep3 (AAVALLPAVLLALLAPRQMATADEA-NH2), which are being developed aimed at interfering with the intracellular protein-protein interaction(PPI) RANK-TRAF6. Our results demonstrated that US-assisted SPPS led to a 14-fold (Pep1) and 4-fold time reduction (Pep2) in peptide assembly compared to the “classical” method. Interestingly, US-assisted SPPS yielded Pep1 in higher purity (82%) than the “classical” SPPS (73%). The significant time reduction combined with high crude peptide purity attained prompted use to apply US-assisted SPPS to the large peptide Pep3, which displays a high number of hydrophobic amino acids and homooligo-sequences. Remarkably, the synthesis of this 25-mer peptide was attained during a “working day” (347 min) in moderate purity (approx. 49%). In conclusion, we have reinforced the importance of using US-SPPS towards facilitating the production of peptides in shorter time with increased efficacy in moderate to high crude purity. This is of special importance for long peptides such as the case of Pep3.

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Chen, Ming, Shuanglong Wang y Xihan Yu. "Cryptand-imidazolium supported total synthesis of the lasso peptide BI-32169 and its d-enantiomer". Chemical Communications 55, n.º 23 (2019): 3323–26. http://dx.doi.org/10.1039/c8cc10301a.

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The first total synthesis of natural lasso peptide is reported, in which cryptand-imidazolium complex support manipulates the peptide chain to achieve a lasso peptide configuration of BI-32169. Moreover, the synthesis of d-enantiomeric lasso peptide via this new method opens up new horizons in the study of lasso peptides.

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46

Rademann, Jörg, Ahsanullah Ahsanullah, Abbas Hassan y Farzana L. Ansari. "Integration of C-Acylation in the Solid-Phase Synthesis of Peptides and Peptidomimetics Employing Meldrum’s Acid, Phosphorus, and Sulfur Ylides". Synthesis 54, n.º 06 (12 de octubre de 2021): 1503–17. http://dx.doi.org/10.1055/a-1667-3648.

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AbstractThe modification of native peptides to peptidomimetics is an important goal in medicinal chemistry and requires, in many cases, the integration of C-acylation steps involving amino acids with classical peptide synthesis. Many classical C-acylation protocols involving Claisen condensations and the use of ylides are not compatible with peptide synthesis, mostly due to the requirements for strong bases leading to epimerization or deprotection of peptides. Meldrum’s acid as well as several specific phosphorus and sulfur ylides, however, are acidic enough to provide reactive C-nucleophiles under mildly basic conditions tolerated during peptide synthesis. This review provides an overview of peptide-compatible C-acylations using Meldrum’s acid and phosphorus and sulfur ylides, and their application in the medicinal chemistry of peptides.1 Introduction2 C-Acylation of Meldrum’s Acid2.1 C-Acylation of Meldrum’s Acid on Solid Phase3 Ylides as Substrates for C-Acylation3.1 C-Acylation of Phosphorus Ylides in Solution Phase3.2 C-Acylation of Solid-Supported Phosphorus Ylides3.3 C-Acylation of Sulfur Ylides3.4 C-Acylation of Solid-Supported Sulfur Ylides4 Miscellaneous Ylides as Acyl Anion Equivalents5 Summary

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47

Chen, W., N. J. Ede, D. C. Jackson, J. McCluskey y A. W. Purcell. "CTL recognition of an altered peptide associated with asparagine bond rearrangement. Implications for immunity and vaccine design." Journal of Immunology 157, n.º 3 (1 de agosto de 1996): 1000–1005. http://dx.doi.org/10.4049/jimmunol.157.3.1000.

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Abstract The extent to which peptides containing chemically and post-translationally modified amino acid side chains are recognized by primed CTL has not been clearly defined. We report on the CTL recognition of a MHC class I-restricted peptide containing a cyclized asparagine (succinimide) residue. This modification of the asparagine side chain is a common intermediate structure during deamidation, isomerization, and bond rearrangements of amide-containing amino acids and also occurs as a side reaction in peptide synthesis. The CTL specifically recognized the succinimide-containing peptide showing only weak cross-reactivity at high concentrations of the parent peptide containing unmodified asparagine. Similarly, CTL raised against the parent peptide did not recognize the succinimide derivative of this peptide. Naturally processed forms of these structures are likely to occur given the importance and frequency of deamidation both in vitro and in vivo. Moreover, since succinimide intermediates of deamidated peptides can occasionally be very stable, these peptides have the potential to act as altered self-Ags with significant implications for autoimmunity. In addition, unwanted and potentially hazardous specificities may be elicited when using synthetic peptides in subunit vaccines in which succinimide residues may form spontaneously during storage or chemical synthesis.

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48

Jacob, Sunil, Nissy Ann Harry, K. K. Binoj K. K. Binoj, Preethy Soosan Thomas y Janey Mary Mathew. "Synthesis of Biologically Active Peptides using Newly Designed N-Vinyl Pyrrolidone Incorporated Flexible Cross linked Polystyrene". Oriental Journal Of Chemistry 38, n.º 5 (31 de octubre de 2022): 1217–26. http://dx.doi.org/10.13005/ojc/380517.

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Synthesis of NS1 and NS2 peptide fragment of hepatitis C virus polyprotein was carried out on a terpolymer- polystyrene, N-vinylpyrrolidone, 1,6-hexanediol diacrylate resin (PS-NVP-HDDA). The radical aqueous suspension polymerisation resulted in the resin, that exhibited high swelling capacity in various solvents. The peptides were synthesized step-wise by Fmoc strategy, established with amino acid analysis and purified using HPLC. The polymer's high degree of swelling might facilitate free reagent interaction with resin-bound functional sites, resulting in an increased rate of amide bond production. The peptides yield and purity obtained from new support was high when compared to Merrifield resin. These peptides synthesis depicts the application of PS-NVP-HDDA resin developed for synthesis of long chain peptides in high homogeneity and high yield.

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49

Cahill, P. A. y A. Hassid. "ANF-C-receptor-mediated inhibition of aortic smooth muscle cell proliferation and thymidine kinase activity". American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 266, n.º 1 (1 de enero de 1994): R194—R203. http://dx.doi.org/10.1152/ajpregu.1994.266.1.r194.

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We have investigated the inhibition of DNA synthesis and cell proliferation by rat atrial natriuretic factor [rANF-(99-126)] and several synthetic peptides that bind selectively to the ANF-C-type clearance receptors in subcultured aortic smooth muscle cells. These peptides decreased serum-induced 1) [3H]thymidine incorporation, 2) cell proliferation, and 3) thymidine kinase activity without altering basal or elevated cAMP or cGMP levels. In contrast, another ANF-C-receptor-binding peptide, des[Gln116,Ser117,Gly118,Leu119,Gly120] rANF-(102-121)-NH2 (cANF), failed to decrease serum-induced mitogenesis, yet 100 nM cANF reversed the inhibition of DNA synthesis and cell proliferation and the decrease of thymidine kinase activity elicited by other C receptor-binding peptides, including rANF-(99-126), rANF-(103-125), and porcine C-type natriuretic peptide [pCNP-(1-22)]. Delayed addition experiments indicated that atrial peptides influence a relatively late event (or events) during the G1 phase of the cell cycle. The inhibition of DNA synthesis by C-receptor-binding atrial peptides appeared to be selective for aortic smooth muscle cells, inasmuch as a potent inhibitory agonist peptide, Cys116-rANF-(102-116), was without significant influence on the incorporation of thymidine in cultured rat mesangial cells or bovine pulmonary artery endothelial cells. These results indicate that atrial natriuretic peptide analogues decrease vascular smooth muscle cell mitogenesis and proliferation by a cyclic nucleotide-independent mechanism involving the C-type receptor. Moreover the inhibition of DNA synthesis by rANF-(99-126) and the neuropeptide pCNP-(1-22) appears to be mediated by the ANF-C-type receptor and is associated with inhibition of thymidine kinase activity.

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50

Grünewald, Jan y Mohamed A. Marahiel. "Chemoenzymatic and Template-Directed Synthesis of Bioactive Macrocyclic Peptides". Microbiology and Molecular Biology Reviews 70, n.º 1 (marzo de 2006): 121–46. http://dx.doi.org/10.1128/mmbr.70.1.121-146.2006.

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SUMMARY Non-ribosomally synthesized peptides have compelling biological activities ranging from antimicrobial to immunosuppressive and from cytostatic to antitumor. The broad spectrum of applications in modern medicine is reflected in the great structural diversity of these natural products. They contain unique building blocks, such as d-amino acids, fatty acids, sugar moieties, and heterocyclic elements, as well as halogenated, methylated, and formylated residues. In the past decades, significant progress has been made toward the understanding of the biosynthesis of these secondary metabolites by nonribosomal peptide synthetases (NRPSs) and their associated tailoring enzymes. Guided by this knowledge, researchers genetically redesigned the NRPS template to synthesize new peptide products. Moreover, chemoenzymatic strategies were developed to rationally engineer nonribosomal peptides products in order to increase or alter their bioactivities. Specifically, chemical synthesis combined with peptide cyclization mediated by nonribosomal thioesterase domains enabled the synthesis of glycosylated cyclopeptides, inhibitors of integrin receptors, peptide/polyketide hybrids, lipopeptide antibiotics, and streptogramin B antibiotics. In addition to the synthetic potential of these cyclization catalysts, which is the main focus of this review, different enzymes for tailoring of peptide scaffolds as well as the manipulation of carrier proteins with reporter-labeled coenzyme A analogs are discussed.

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