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cyclization peptides

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https://www.readbyqxmd.com/read/28912270/the-periplasmic-transaminase-ptaa-of-pseudomonas-fluorescens-converts-the-glutamic-acid-residue-at-the-pyoverdine-fluorophore-to-%C3%AE-ketoglutaric-acid
#1
Michael T Ringel, Gerald Draeger, Thomas Brueser
The periplasmic conversion of ferribactin to pyoverdine is essential for siderophore biogenesis in fluorescent pseudomonads, such as pathogenic Pseudomonas aeruginosa or plant growth promoting P. fluorescens The non-ribosomal peptide ferribactin undergoes cyclizations and oxidations that result in the fluorophore, and a strictly conserved fluorophore-bound glutamic acid residue is converted to a range of variants, including succinamide, succinic acid, and α-ketoglutaric acid residues. We recently discovered that the pyridoxal phosphate (PLP)-containing enzyme PvdN is responsible for the generation of the succinamide, which can be hydrolyzed to succinic acid...
September 14, 2017: Journal of Biological Chemistry
https://www.readbyqxmd.com/read/28905052/cyclic-peptide-production-using-a-macrocyclase-with-enhanced-substrate-promiscuity-and-relaxed-recognition-determinants
#2
Cristina N Alexandru-Crivac, Christian Umeobika, Niina Leikoski, Jouni Jokela, Kirstie A Rickaby, André M Grilo, Peter Sjö, Alleyn T Plowright, Mohannad Idress, Eike Siebs, Ada Nneoyi-Egbe, Matti Wahlsten, Kaarina Sivonen, Marcel Jaspars, Laurent Trembleau, David P Fewer, Wael E Houssen
Macrocyclic peptides have promising therapeutic potential but the scaling up of their chemical synthesis is challenging. The cyanobactin macrocyclase PatGmac is an efficient tool for production but is limited to substrates containing 6-11 amino acids and at least one thiazoline or proline. Here we report a new cyanobactin macrocyclase that can cyclize longer peptide substrates and those not containing proline/thiazoline and thus allows exploring a wider chemical diversity.
September 14, 2017: Chemical Communications: Chem Comm
https://www.readbyqxmd.com/read/28885830/oligoprolines-as-molecular-entities-for-controlling-distance-in-biological-and-material-sciences
#3
Stefanie Dobitz, Matthew R Aronoff, Helma Wennemers
Nature utilizes large biomolecules to fulfill tasks that require spatially well-defined arrangements at the molecular level such as electron transfer, ligand-receptor interactions, or catalysis. The creation of synthetic molecules that enable precise control over spacing and functionalization provides opportunities across diverse disciplines. Key requirements of functionalizable oligomeric scaffolds include the specific control of their molecular properties where the correct balance of flexibility and rigidity must be maintained in addition to the prerequisite of defined length...
September 8, 2017: Accounts of Chemical Research
https://www.readbyqxmd.com/read/28885004/gold-catalyzed-solid-phase-synthesis-of-3-4-dihydropyrazin-2-1h-ones-relevant-pharmacophores-and-peptide-backbone-constraints
#4
Adam Přibylka, Viktor Krchňák
Here, we report the efficient solid-phase synthesis of N-propargyl peptides using Fmoc-amino acids and propargyl alcohol as key building blocks. Gold-catalyzed nucleophilic addition to the triple bond induced C-N bond formation, which triggered intramolecular cyclization, yielding 1,3,4-trisubstituted-5-methyl-3,4-dihydropyrazin-2(1H)-ones. Conformations of acyclic and constrained peptides were compared using a two-step conformer distribution analysis at the molecular mechanics level and density functional theory...
September 12, 2017: ACS Combinatorial Science
https://www.readbyqxmd.com/read/28882503/synthesis-and-%C3%AE-sheet-propensity-of-constrained-n-amino-peptides
#5
Matthew P Sarnowski, Kyle P Pedretty, Nicole Giddings, H Lee Woodcock, Juan R Del Valle
The stabilization of β-sheet secondary structure through peptide backbone modification represents an attractive approach to protein mimicry. Here, we present strategies toward stable β-hairpin folds based on peptide strand N-amination. Novel pyrazolidinone and tetrahydropyridazinone dipeptide constraints were introduced via on-resin Mitsunobu cyclization between α-hydrazino acid residues and a serine or homoserine side chain. Acyclic and cyclic N-amino peptide building blocks were then evaluated for their effect on β-hairpin stability in water using a GB1-derived model system...
August 31, 2017: Bioorganic & Medicinal Chemistry
https://www.readbyqxmd.com/read/28866879/versatility-of-prolyl-oligopeptidase-b-in-peptide-macrocyclization
#6
Robert Michael Sgambelluri, Miranda O Smith, Jonathan D Walton
Cyclic peptides are promising compounds for new chemical biological tools and therapeutics due to their structural diversity, resistance to proteases, and membrane permeability. Amatoxins, the toxic principles of poisonous mushrooms, are biosynthesized on ribosomes as 35-mer precursor peptides which are ultimately converted to hydroxylated bicyclic octapeptides. The initial cyclization steps, catalyzed by a dedicated prolyl oligopeptidase (POPB), involves removal of the 10-amino acid leader sequence from the precursor peptide and transpeptidation to produce a monocyclic octapeptide intermediate...
September 2, 2017: ACS Synthetic Biology
https://www.readbyqxmd.com/read/28851841/backbone-cyclization-of-analgesic-conotoxin-gexiva-facilitates-direct-folding-of-the-ribbon-isomer
#7
Xiaosa Wu, Yen-Hua Huang, Quentin Kaas, Peta J Harvey, Conan K Wang, Han-Shen Tae, David J Adams, David J Craik
Conotoxin GeXIVA inhibits the α9α10 nicotinic acetylcholine receptor (nAChR) and is analgesic in animal models of pain. α-conotoxins have four cysteines, which can have three possible disulfide connectivities: globular (CysI-CysIII and CysII-CysIV); ribbon (CysI-CysIV and CysII-CysIII) or bead (CysI-CysII and CysIII-CysIV). Native α-conotoxins preferably adopt the globular connectivity, and previous studies of α-conotoxins have focused on the globular isomers as the ribbon and bead isomers typically have lower potency at nAChRs than the globular form...
August 28, 2017: Journal of Biological Chemistry
https://www.readbyqxmd.com/read/28846367/structure-and-functional-analysis-of-clbq-an-unusual-intermediate-releasing-thioesterase-from-the-colibactin-biosynthetic-pathway
#8
Naga Sandhya Guntaka, Alan R Healy, Jason M Crawford, Seth B Herzon, Steven D Bruner
Colibactin is a genotoxic hybrid nonribosomal peptide/polyketide secondary metabolite produced by various pathogenic and probiotic bacteria residing in the human gut. The presence of colibactin metabolites has been correlated to colorectal cancer formation in several studies. The specific function of many gene products in the colibactin gene cluster can be predicted. However, the role of ClbQ, a type II editing thioesterase, has not been established. The importance of ClbQ has been demonstrated by genetic deletions that abolish colibactin cytotoxic activity, and recent studies suggest an atypical role in releasing pathway intermediates from the assembly line...
September 8, 2017: ACS Chemical Biology
https://www.readbyqxmd.com/read/28833783/intramolecular-cyclization-of-the-antimicrobial-peptide-polybia-mpi-with-triazole-stapling-influence-on-stability-and-bioactivity
#9
Beijun Liu, Wei Zhang, Sanhu Gou, Haifeng Huang, Jia Yao, Zhibin Yang, Hui Liu, Chao Zhong, Beiyin Liu, Jingman Ni, Rui Wang
Cationic antimicrobial peptides have attracted increasing attention as a novel class of antibiotics to treat infectious diseases caused by pathogenic bacteria. However, susceptibility to protease is a shortcoming in their development. Cyclization is one approach to increase the proteolytic resistance of peptides. Therefore, to improve the proteolytic resistance of Polybia-MPI, we have synthesized the MPI cyclic analogs C-MPI-1 (i-to-i+4) and C-MPI-2 (i-to-i+6) by copper(I)-catalyzed azide-alkyne cycloaddition...
August 23, 2017: Journal of Peptide Science: An Official Publication of the European Peptide Society
https://www.readbyqxmd.com/read/28833777/peptide-macrocycles-developed-from-precisely-regulated-cyclization-of-unprotected-peptides
#10
Jinghui Wang, Mirao Zha, Qianran Fei, Weidong Liu, Yibing Zhao, Chuanliu Wu
Peptide macrocycles have been attractive scaffolds for the development of ligands and inhibitors to proteins, which have the potential of being developed as potent drugs. Novel strategies for peptide macrocyclization should be of particular interest to peptide drug design and discovery. Here, we report an efficient strategy for designing and synthesizing macrocyclic peptides, which relies on the precisely-regulated and efficient one-pot cyclization of unprotected peptides with 2,3,5,6-tetrafluoroterephthalonitrile (4F-2CN)...
August 22, 2017: Chemistry: a European Journal
https://www.readbyqxmd.com/read/28833706/diversity-oriented-syntheses-by-combining-cuaac-and-stereoselective-incic-reactions-with-peptides
#11
Yuanyuan Wang, Anders Ø Madsen, Frederik Diness, Morten Meldal
Cascade reactions proceeding through peptide-derived N-carbamoyl iminium ions are reported. Two new reactions of N-carbamoyl iminium ions are described, including a stereoselective double cyclization generating N,N'-aminals and an acid-promoted auto-oxidation. Mechanistic investigations revealed that the N,N'-aminal formation is reversible under strongly acidic conditions. Both of these new reactions proved to be completely orthogonal to subsequent CuAAC chemistry. The reactions were performed in solution and on solid support...
August 18, 2017: Chemistry: a European Journal
https://www.readbyqxmd.com/read/28813139/tunable-injectable-hydrogels-based-on-peptide-cross-linked-cyclized-polymer-nanoparticles-for-neural-progenitor-cell-delivery
#12
Tianyu Zhao, Drew L Sellers, Yilong Cheng, Philip J Horner, Suzie H Pun
A PEG-based cyclized vinyl polymer was synthesized via one-step RAFT polymerization and used as a precursor of injectable hydrogels. Dithiol linkers including laminin-derived peptides containing IKVAV and YIGSR sequences and DTT were used for gelation. Fast and adjustable gelation rate was achieved through nucleophile-initiated thiol-Michael reaction under physiological conditions. Low swelling ratio and moderate degradation rate of the formed hydrogels were observed. 3D encapsulation of neural progenitor cells in the synthetic hydrogel showed good cell viability over 8 days...
August 25, 2017: Biomacromolecules
https://www.readbyqxmd.com/read/28807931/identification-of-novel-growth-regulators-in-plant-populations-expressing-random-peptides
#13
Zhilong Bao, Maureen A Clancy, Raquel F Carvalho, Kiona Elliott, Kevin M Folta
The use of chemical genomics approaches allows the identification of small molecules that integrate into biological systems, thereby changing discrete processes that influence growth, development or metabolism. Libraries of chemicals are applied to living systems, and changes in phenotype are observed, potentially leading to the identification of new growth regulators. This work describes an approach that is the nexus of chemical-genomics and synthetic biology. Here each plant in an extensive population synthesizes a unique small peptide arising from a transgene composed of a randomized nucleic acid sequence core, flanked by translational start, stop, and cysteine-encoding (for disulfide cyclization) sequences...
August 14, 2017: Plant Physiology
https://www.readbyqxmd.com/read/28799768/total-synthesis-and-stereochemical-assignment-of-gymnopeptides-a-and-b
#14
Zhengyin Pan, Chunlei Wu, Wei Wang, Zhehong Cheng, Guiyang Yao, Ke Liu, Hongchang Li, Lijing Fang, Wu Su
Gymnopeptides A and B are unprecedented highly N-methylated cyclic β-hairpin octadecapeptides with striking antiproliferative activities isolated from the mushroom Gymnopus fusipes. Using Fmoc-based solid-phase peptide synthesis, followed by macrolactamization of the resulting linear peptides, the first total synthesis of gymnopeptides A and B was successfully achieved in this study. The coupling methods used for the solid-phase synthesis and the cyclization were optimized, and the configuration of the Ser1/Thr1 residue in gymnopeptide A/B was determined to be l...
August 11, 2017: Organic Letters
https://www.readbyqxmd.com/read/28770939/chemical-optimization-of-macrocyclic-hiv-1-inactivators-for-improving-potency-and-increasing-the-structural-diversity-at-the-triazole-ring
#15
Adel A Rashad, Kriti Acharya, Ann Haftl, Rachna Aneja, Alexej Dick, Andrew P Holmes, Irwin Chaiken
HIV-1 entry inhibition remains an urgent need for AIDS drug discovery and development. We previously reported the discovery of cyclic peptide triazoles (cPTs) that retain the HIV-1 irreversible inactivation functions of the parent linear peptides (PTs) and have massively increased proteolytic resistance. Here, in an initial structure-activity relationship investigation, we evaluated the effects of variations in key structural and functional components of the cPT scaffold in order to produce a platform for developing next-generation cPTs...
August 3, 2017: Organic & Biomolecular Chemistry
https://www.readbyqxmd.com/read/28767081/new-insights-in-the-design-of-bioactive-peptides-and-chelating-agents-for-imaging-and-therapy-in-oncology
#16
REVIEW
Anna Lucia Tornesello, Luigi Buonaguro, Maria Lina Tornesello, Franco Maria Buonaguro
Many synthetic peptides have been developed for diagnosis and therapy of human cancers based on their ability to target specific receptors on cancer cell surface or to penetrate the cell membrane. Chemical modifications of amino acid chains have significantly improved the biological activity, the stability and efficacy of peptide analogues currently employed as anticancer drugs or as molecular imaging tracers. The stability of somatostatin, integrins and bombesin analogues in the human body have been significantly increased by cyclization and/or insertion of non-natural amino acids in the peptide sequences...
August 2, 2017: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
https://www.readbyqxmd.com/read/28741926/redesigned-spider-peptide-with-improved-antimicrobial-and-anticancer-properties
#17
Sónia Troeira Henriques, Nicole Lawrence, Stephanie Chaousis, Anjaneya S Ravipati, Olivier Cheneval, Aurélie H Benfield, Alysha G Elliott, Angela Maria Kavanagh, Matthew A Cooper, Lai Yue Chan, Yen-Hua Huang, David J Craik
Gomesin, a disulfide-rich antimicrobial peptide produced by the Brazilian spider Acanthoscurria gomesiana, has been shown to be potent against Gram-negative bacteria and to possess selective anticancer properties against melanoma cells. In a recent study, a backbone cyclized analogue of gomesin was shown to be as active but more stable than its native form. In the current study, we were interested in improving the antimicrobial properties of the cyclic gomesin, understanding its selectivity toward melanoma cells and elucidating its antimicrobial and anticancer mode of action...
September 15, 2017: ACS Chemical Biology
https://www.readbyqxmd.com/read/28719188/phage-selection-of-cyclic-peptides-for-application-in-research-and-drug-development
#18
Kaycie Deyle, Xu-Dong Kong, Christian Heinis
Cyclic peptides can bind to protein targets with high affinities and selectivities, which makes them an attractive modality for the development of research reagents and therapeutics. Additional properties, including low inherent toxicity, efficient chemical synthesis, and facile modification with labels or immobilization reagents, increase their attractiveness. Cyclic peptide ligands against a wide range of protein targets have been isolated from natural sources such as bacteria, fungi, plants, and animals...
July 18, 2017: Accounts of Chemical Research
https://www.readbyqxmd.com/read/28715095/a-self-sacrificing-n-methyltransferase-is-the-precursor-of-the-fungal-natural-product-omphalotin
#19
Sascha Ramm, Bartlomiej Krawczyk, Agnes Mühlenweg, Annette Poch, Eva Mösker, Roderich D Süssmuth
Research on ribosomally synthesized and posttranslationally modified peptides (RiPPs) has led to an increasing understanding of biosynthetic mechanisms, mostly drawn from bacterial examples. In contrast, reports on RiPPs from fungal producers, apart from the amanitins and phalloidins, are still scarce. The fungal cyclopeptide omphalotin A carries multiple N-methylations on the peptide backbone, a modification previously known only from nonribosomal peptides. Mining the genome of the omphalotin-producing fungus for a precursor peptide led to the identification of two biosynthesis genes, one encoding a methyltransferase OphMA that catalyzes the automethylation of its C-terminus, which is then released and cyclized by the protease OphP...
July 17, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28715083/macroevolution-a-new-method-for-the-rapid-generation-of-novel-scaffold-diverse-macrocyclic-libraries
#20
Jörn Saupe, Oliver Kunz, Lars Ole Haustedt, Sven Jakupovic, Christian Mang
Macrocycles are a structural class bearing great promise for future challenges in medicinal chemistry. Nevertheless, there are few flexible approaches for the rapid generation of structurally diverse macrocyclic compound collections. Here, an efficient method for the generation of novel macrocyclic peptide-based scaffolds is reported. The process, named here as "MacroEvoLution", is based on a cyclization screening approach that gives reliable access to novel macrocyclic architectures. Classification of building blocks into specific pools ensures that scaffolds with orthogonally addressable functionalities are generated, which can easily be used for the generation of structurally diverse compound libraries...
July 17, 2017: Chemistry: a European Journal
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