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https://www.readbyqxmd.com/read/28534477/decoding-and-reprogramming-fungal-iterative-nonribosomal-peptide-synthetases
#1
Dayu Yu, Fuchao Xu, Shuwei Zhang, Jixun Zhan
Nonribosomal peptide synthetases (NRPSs) assemble a large group of structurally and functionally diverse natural products. While the iterative catalytic mechanism of bacterial NRPSs is known, it remains unclear how fungal NRPSs create products of desired length. Here we show that fungal iterative NRPSs adopt an alternate incorporation strategy. Beauvericin and bassianolide synthetases have the same C1-A1-T1-C2-A2-MT-T2a-T2b-C3 domain organization. During catalysis, C3 and C2 take turns to incorporate the two biosynthetic precursors into the growing depsipeptide chain that swings between T1 and T2a/T2b with C3 cyclizing the chain when it reaches the full length...
May 23, 2017: Nature Communications
https://www.readbyqxmd.com/read/28520410/proteolytically-stable-cyclic-decapeptide-for-breast-cancer-cell-targeting
#2
Yogita Raghuwanshi, Hashem Rajab Etayash, Rania Soudy, Igor Paiva, Afsaneh Lavasanifar, Kamaljit Kaur
Starting with a previously reported linear breast cancer targeting decapeptide WxEAAYQkFL, here we report the synthesis of a novel cyclic peptide analogue cyclicWXEAAYQkFL. The N- to C-terminus amide cyclized peptide with one D-amino acid (k) displayed higher uptake by breast cancer cells, with minimal uptake by the non-cancerous cells compared to the linear peptide with two D-amino acids (x and k), and was stable toward proteolytic degradation. When immobilized on gold microcantilever surface, the cyclic peptide was able to capture breast cancer cells specifically and sense samples with ≥25 cancer cells/mL...
May 18, 2017: Journal of Medicinal Chemistry
https://www.readbyqxmd.com/read/28504677/%C3%AE-lactone-formation-during-product-release-from-a-nonribosomal-peptide-synthetase
#3
Jason E Schaffer, Margaret R Reck, Neha K Prasad, Timothy A Wencewicz
Nonribosomal peptide synthetases (NRPSs) are multidomain modular biosynthetic assembly lines that polymerize amino acids into a myriad of biologically active nonribosomal peptides (NRPs). NRPS thioesterase (TE) domains employ diverse release strategies for off-loading thioester-tethered polymeric peptides from termination modules typically via hydrolysis, aminolysis, or cyclization to provide mature antibiotics as carboxylic acids/esters, amides, and lactams/lactones, respectively. Here we report the enzyme-catalyzed formation of a highly strained β-lactone ring during TE-mediated cyclization of a β-hydroxythioester to release the antibiotic obafluorin (Obi) from an NRPS assembly line...
May 15, 2017: Nature Chemical Biology
https://www.readbyqxmd.com/read/28498670/palladium-catalyzed-aminocarbonylation-in-solid-phase-peptide-synthesis-a-method-for-capping-cyclization-and-isotope-labeling
#4
Anna Skogh, Stig D Friis, Troels Skrydstrup, Anja Sandström
A new synthetic approach for introducing N-capping groups onto peptides attached to a solid support, combining aminocarbonylation under mild conditions using a palladacycle precatalyst and solid-phase peptide synthesis, is reported. The use of a silacarboxylic acid as an in situ CO-releasing molecule allowed the reaction to be performed in a single vial. The method also enables versatile substitution of side chains, side-chain-to-side-chain cyclizations, and selective [(13)C] acyl labeling of modified peptides...
May 12, 2017: Organic Letters
https://www.readbyqxmd.com/read/28483279/macrocyclization-of-a-potent-pace4-inhibitor-benefits-and-limitations
#5
Teresa Łepek, Anna Kwiatkowska, Frédéric Couture, Kévin Ly, Roxane Desjardins, Yves Dory, Adam Prahl, Robert Day
PACE4, one of the seven members of the proprotein convertase family, plays an important role in the progression of prostate cancer. Therefore, its inhibition has become an attractive target to develop new therapies against this disease. Recently, we have developed a highly potent and selective PACE4 inhibitor, known as the multi-Leu peptide with the following sequence Ac-LLLLRVKR-NH2. Herein, with the aim of improving the stability profile of this inhibitor for potential in vivo application, we investigated the impact of different cyclization strategies...
April 23, 2017: European Journal of Cell Biology
https://www.readbyqxmd.com/read/28475844/a-blind-test-of-computational-technique-for-predicting-the-likelihood-of-peptide-sequences-to-cyclize
#6
Jonathan Booth, Christina-Nicoleta Alexandru-Crivac, Kirstie A Rickaby, Ada F Nneoyiegbe, Ugochukwu Umeobika, Andrew R McEwan, Laurent Trembleau, Marcel Jaspars, Wael E Houssen, Dmitrii V Shalashilin
An in silico computational technique for predicting peptide sequences that can be cyclized by cyanobactin macrocyclases, e.g., PatGmac, is reported. We demonstrate that the propensity for PatGmac-mediated cyclization correlates strongly with the free energy of the so-called pre-cyclization conformation (PCC), which is a fold where the cyclizing sequence C and N termini are in close proximity. This conclusion is driven by comparison of the predictions of boxed molecular dynamics (BXD) with experimental data, which have achieved an accuracy of 84%...
May 18, 2017: Journal of Physical Chemistry Letters
https://www.readbyqxmd.com/read/28466571/synthesis-of-relaxin-2-and-insulin-like-peptide-5-enabled-by-novel-tethering-and-traceless-chemical-excision
#7
Kishore Thalluri, Binbin Kou, Xu Yang, Alexander N Zaykov, John P Mayer, Vasily M Gelfanov, Fa Liu, Richard D DiMarchi
This report presents an entirely chemical, general strategy for the synthesis of relaxin-2 and insulin-like peptide 5. Historically, these two peptides have represented two of the more synthetically challenging members of the insulin superfamily. The key synthetic steps involve two sequential oxime ligations to covalently link the individual A-chain and B-chain, followed by disulfide bond formation under aqueous, redox conditions. This is followed by two chemical reactions that employ diketopiperazine cyclization-mediated cleavage and ester hydrolysis to liberate the connecting peptide and the heterodimeric product...
May 3, 2017: Journal of Peptide Science: An Official Publication of the European Peptide Society
https://www.readbyqxmd.com/read/28460065/sbspksv2-structure-based-sequence-analysis-of-polyketide-synthases-and-non-ribosomal-peptide-synthetases
#8
Shradha Khater, Money Gupta, Priyesh Agrawal, Neetu Sain, Jyoti Prava, Priya Gupta, Mansi Grover, Narendra Kumar, Debasisa Mohanty
Genome guided discovery of novel natural products has been a promising approach for identification of new bioactive compounds. SBSPKS web-server has been a valuable resource for analysis of polyketide synthase (PKS) and non-ribosomal peptide synthetase (NRPS) gene clusters. We have developed an updated version - SBSPKSv2 which is based on comprehensive analysis of sequence, structure and secondary metabolite chemical structure data from 311 experimentally characterized PKS/NRPS gene clusters with known biosynthetic products...
April 29, 2017: Nucleic Acids Research
https://www.readbyqxmd.com/read/28457894/lipophilic-peptide-character-what-oral-barriers-fear-the-most
#9
REVIEW
Ožbej Zupančič, Andreas Bernkop-Schnürch
Peptide therapeutics is currently one of the fastest growing markets worldwide and consequently convenient ways of administration for these drugs are highly on demand. In particular, oral dosage forms would be preferred. A relative large molecular weight and high hydrophilicity, however, result in comparatively very low oral bioavailability being in most cases below 1%. Lipid based formulations (LBF), in particular self-emulsifying drug delivery systems (SEDDS) and solid lipid nanoparticles (SLN) as well as liposomes are among the most promising tools for oral peptide delivery...
April 28, 2017: Journal of Controlled Release: Official Journal of the Controlled Release Society
https://www.readbyqxmd.com/read/28451290/activation-and-characterization-of-a-cryptic-gene-cluster-reveals-a-cyclization-cascade-for-polycyclic-tetramate-macrolactams
#10
Subhasish Saha, Wenjun Zhang, Guangtao Zhang, Yiguang Zhu, Yuchan Chen, Wei Liu, Chengshan Yuan, Qingbo Zhang, Haibo Zhang, Liping Zhang, Weimin Zhang, Changsheng Zhang
Polycyclic tetramate macrolactams (PTMs) are a growing class of natural products and are derived from a hybrid polyketide synthase (PKS)/non-ribosomal peptide synthetase (NRPS) pathway. PTM biosynthetic gene clusters are conserved and widely distributed in bacteria, however, most of them remain silent. Herein we report the activation of a PTM gene cluster in marine-derived Streptomyces pactum SCSIO 02999 by promoter engineering and heterologous expression, leading to the discovery of six new PTMs, pactamides A-F (11-16), with potent cytotoxic activity upon several human cancer cell lines...
February 1, 2017: Chemical Science
https://www.readbyqxmd.com/read/28444893/catalytic-reductive-synthesis-and-direct-derivatization-of-unprotected-aminoindoles-aminopyrroles-and-iminoindolines
#11
Leonardus H Leijendekker, Jens Weweler, Tobias M Leuther, Jan Streuff
A titanium(III)-catalyzed radical cyclization to unprotected 3-aminoindoles, 3-aminopyrroles, or 3-iminoindolines is reported. The reaction is non-hazardous, scalable, and allows facile isolation of the free products by extraction. The method is demonstrated on a large substrate scope and it further allows the direct installation of various nitrogen protecting groups or the synthesis of building blocks for peptide chemistry in a single sequence. Fused bisindoles can be directly accessed from the cyclization products...
April 26, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28428776/mapping-and-identification-of-antifungal-peptides-in-the-putative-antifungal-protein-afpb-from-the-filamentous-fungus-penicillium-digitatum
#12
Sandra Garrigues, Mónica Gandía, Attila Borics, Florentine Marx, Paloma Manzanares, Jose F Marcos
Antifungal proteins (AFPs) from Ascomycetes are small cysteine-rich proteins that are abundantly secreted and show antifungal activity against non-producer fungi. A gene coding for a class B AFP (AfpB) was previously identified in the genome of the plant pathogen Penicillium digitatum. However, previous attempts to detect the AfpB protein were not successful despite the high expression of the corresponding afpB gene. In this work, the structure of the putative AfpB was modeled. Based on this model, four synthetic cysteine-containing peptides, PAF109, PAF112, PAF118, and PAF119, were designed and their antimicrobial activity was tested and characterized...
2017: Frontiers in Microbiology
https://www.readbyqxmd.com/read/28406518/a-multicomponent-macrocyclization-strategy-to-natural-product-like-cyclic-lipopeptides-synthesis-and-anticancer-evaluation-of-surfactin-and-mycosubtilin-analogues
#13
Micjel C Morejón, Annegret Laub, Goran N Kaluđerović, Alfredo R Puentes, Ali N Hmedat, Anselmo J Otero-González, Daniel G Rivera, Ludger A Wessjohann
A multicomponent macrocyclization strategy towards cyclic lipopeptides is described. The approach relies on the utilization of the Ugi and Passerini multicomponent reactions for the cyclization of peptides and oxo-peptides, and here it is employed for the construction of a small library of analogues of the natural products mycosubtilin and surfactin A. A key feature of this method is the simultaneous incorporation of either one or two exocyclic lipid tails along with the macrocyclic ring closure, which is only possible due to the multicomponent nature of the macrocyclization step...
May 3, 2017: Organic & Biomolecular Chemistry
https://www.readbyqxmd.com/read/28395122/cu-%C3%B0-mediated-denitrogenative-macrocyclization-for-the-synthesis-of-cyclic-%C3%AE-3%C3%AE-tetrapeptide-analogs
#14
Chun-Chi Chen, Sheng-Fu Wang, Yung-Yu Su, Yuya A Lin, Po-Chiao Lin
A copper(I)-mediated denitrogenative reaction has been successfully developed in the preparation of cyclic tetrapeptides. A key reactive intermediate, ketenimine, triggers the key intramolecular cyclization by the terminal amine group and therefore generates an internal β-amino acid with an amidine linkage. The chemistry developed here provides a new synthetic route for the preparation of cyclic α3β-tetrapeptide analogs which are rich in information to the conformational study of macrocycles as well as important biologically active peptides...
April 10, 2017: Chemistry, An Asian Journal
https://www.readbyqxmd.com/read/28387471/arrangement-of-proteinogenic-%C3%AE-amino-acids-on-a-cyclic-peptide-comprising-alternate-biphenyl-cored-%C3%AE-amino-acids
#15
Shohei Tashiro, Masayuki Chiba, Mitsuhiko Shionoya
Aiming at precisely arranging several proteinogenic α-amino acids on a folded scaffold, we have developed a cyclic hexapeptide comprising an alternate sequence of biphenyl-cored ζ-amino acids and proteinogenic α-amino acids such as l-leucine. The amino acids were connected by typical peptide synthesis, and the resultant linear hexapeptide was intramolecularly cyclized to form a target cyclic peptide. Theoretical analyses and NMR spectroscopy suggested that the cyclic peptide was folded into an unsymmetrical conformation, and the structure was likely to be flexible in CHCl3 ...
April 7, 2017: Chemistry, An Asian Journal
https://www.readbyqxmd.com/read/28382155/preclinical-melanoma-imaging-with-68-ga-labeled-%C3%AE-melanocyte-stimulating-hormone-derivatives-using-pet
#16
Chengcheng Zhang, Zhengxing Zhang, Kuo-Shyan Lin, Jinhe Pan, Iulia Dude, Navjit Hundal-Jabal, Nadine Colpo, François Bénard
It is estimated that melanoma accounted for 76,380 new cases and 10,130 deaths in the United States in 2016. The melanocortin 1 receptor (MC1R) is highly expressed in the vast majority of melanomas, which makes it an attractive target for molecular imaging and radionuclide therapy. Lactam bridge-cyclized α-melanocyte-stimulating hormone (Ac-Nle(4)-cyclo[Asp(5)-His-D-Phe(7)-Arg-Trp-Lys(10)]-NH2, or Nle-CycMSHhex) analogues have been successfully developed and studied for MC1R-targeted imaging, predominantly with single-photon emission computed tomography (SPECT)...
2017: Theranostics
https://www.readbyqxmd.com/read/28378889/the-prebiotic-c-terminal-elongation-of-peptides-can-be-initiated-by-n-carbamoyl-amino-acids
#17
Ninette Abou Mrad, Ghinwa Ajram, Jean-Christophe Rossi, Laurent Boiteau, Fabrice Duvernay, Robert Pascal, Gregoire Danger
The formation of peptides upon EDC promoted activation of N-carbamoylamino acids (CAA), was considered in the scope of our recent works on carbodiimide promoted C-terminus elongation of peptides in a prebiotic context. Thus EDC promoted activation of CAA derivatives of Tyr(Me) or Ala in dilute aqueous medium pH 5.5-6.5 in the presence of excess of AA, resulted in peptide formation via C-terminus activation / elongation. Kinetic results similar to those of EDC-mediated activation of N-acyl-AA lead us to postulate the formation of a 2-amino-5(4H)-oxazolone intermediate by cyclization of the activated CAA, in spite of the absence of epimerization occurred at CAA residues...
April 5, 2017: Chemistry: a European Journal
https://www.readbyqxmd.com/read/28377579/vlp-based-vaccine-induces-immune-control-of-staphylococcus-aureus-virulence-regulation
#18
Seth M Daly, Jason A Joyner, Kathleen D Triplett, Bradley O Elmore, Srijana Pokhrel, Kathryn M Frietze, David S Peabody, Bryce Chackerian, Pamela R Hall
Staphylococcus aureus is the leading cause of skin and soft tissue infections (SSTIs) and mounting antibiotic resistance requires innovative treatment strategies. S. aureus uses secreted cyclic autoinducing peptides (AIPs) and the accessory gene regulator (agr) operon to coordinate expression of virulence factors required for invasive infection. Of the four agr alleles (agr types I-IV and corresponding AIPs1-4), agr type I isolates are most frequently associated with invasive infection. Cyclization via a thiolactone bond is essential for AIP function; therefore, recognition of the cyclic form of AIP1 may be necessary for antibody-mediated neutralization...
April 4, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28370688/impact-of-the-amino-acid-sequence-on-the-conformation-of-side-chain-lactam-bridged-octapeptides
#19
Saskia Neukirchen, Viktoria Krieger, Cornelia Roschger, Mario Schubert, Brigitta Elsässer, Chiara Cabrele
Synthetic helical peptides are valuable scaffolds for the development of modulators of protein-protein interactions involving helical motifs. Backbone-to-side chain or side chain-to-side chain constraints have been and still are intensively exploited to stabilize short α-helices. Very often, these constraints have been combined with backbone modifications induced by Cα-tetrasubstituted, β-, or γ-amino acids, which facilitate the α-peptide or α/β/γ-peptide adopting an α-helical conformation. In this work, we investigated the helical character of octapeptides that were cyclized by a Lys-Asp-(i,i + 4)-lactam bridge...
March 29, 2017: Journal of Peptide Science: An Official Publication of the European Peptide Society
https://www.readbyqxmd.com/read/28333237/new-paenibacillus-strain-produces-a-family-of-linear-and-cyclic-antimicrobial-lipopeptides-cyclization-is-not-essential-for-their-antimicrobial-activity
#20
En Huang, Xu Yang, Liwen Zhang, Sun Hee Moon, Ahmed E Yousef
A new bacterial isolate, Paenibacillus sp. OSY-N, showed potent antimicrobial activity against Gram-negative and Gram-positive bacteria. Antimicrobials produced by this strain were purified by reverse-phase high performance liquid chromatography (HPLC). Structural analysis, using mass spectrometry (MS), of a single active HPLC fraction revealed two known cyclic lipopeptides, BMY-28160 and permetin A, a new cyclic lipopeptide, and the linear counterparts of these cyclic compounds. The latter were designated as paenipeptin A, B and C, respectively...
February 25, 2017: FEMS Microbiology Letters
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