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cyclization peptides

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https://www.readbyqxmd.com/read/27924732/the-effect-of-a-hexanoic-acid-linker-insertion-on-the-pharmacokinetics-and-tumor-targeting-properties-of-the-melanoma-imaging-agent-99mtc-hynic-cycmsh
#1
Vania Teixeira, Marcelo Fernández, Natalia Oddone, Xiuli Zhang, Fabio Gallazzi, Hugo Cerecetto, Juan Pablo Gambini, Williams Porcal, Pablo Cabral, Thomas P Quinn
BACKGROUND: Lactam cyclized alpha-melanocyte stimulating hormone (α-MSH) analogues exhibit high stability and affinity for the MC1-R receptors over expressed in melanoma cells. Recently, we reported a novel <sup>99m</sup>Tc-HYNIC-cycMSH<sub>4-13</sub> analogue with the HYNIC chelator directly attached to the lactam cyclized ring. OBJECTIVE: In this study we proposed the introduction of a 6-aminohexanoic acid (Ahx) linker between the HYNIC chelator and lactam cyclized peptide cycMSH4-13 to reduce steric hindrance and improve the melanoma targeting and imaging proprieties of the radiolabeled peptide...
December 6, 2016: Anti-cancer Agents in Medicinal Chemistry
https://www.readbyqxmd.com/read/27900387/a-modification-specific-peptide-based-immunization-approach-using-crm197-carrier-protein-development-of-a-selective-vaccine-against-pyroglutamate-a%C3%AE-peptides
#2
Valérie Vingtdeux, Haitian Zhao, Pallavi Chandakkar, Christopher M Acker, Peter Davies, Philippe Marambaud
Strategies aimed at reducing cerebral accumulation of the amyloid-β (Aβ) peptides have therapeutic potential in Alzheimer's disease (AD). Aβ immunization has proven to be effective at promoting Aβ clearance in animal models but adverse effects have hampered its clinical evaluation. The first anti-Aβ immunization clinical trial, which assessed a full-length Aβ1-42 vaccine, increased the risk of encephalitis most likely because of autoimmune pro-inflammatory T helper 1 (Th1) response against all forms of Aβ...
November 28, 2016: Molecular Medicine
https://www.readbyqxmd.com/read/27882883/electrospray-ionization-tandem-mass-spectrometric-study-of-protonated-and-alkali-cationized-%C3%AE-%C3%AE%C2%B5-hybrid-peptides-differentiation-of-a-pair-of-dipeptide-positional-isomers
#3
A Ramesh Babu, G Raju, C Purna Chander, B Shoban Babu, R Srinivas, G V M Sharma
A new class of Boc-N-protected hybrid peptides derived from L- Ala and ε(6)-Caa (L-Ala = L-Alanine, Caa = C-linked carboamino acid derived from D-xylose) have been studied by positive ion electrospray ionization (ESI) ion-trap tandem mass spectrometry (MS/MS). MS(n) spectra of protonated and alkali-cationized hybrid peptides produce characteristic fragmentation involving the peptide backbone, the tert-butyloxycarbonyl (Boc) group, and the side chain. The dipeptide positional isomers are differentiated by the collision-induced dissociation (CID) of the protonated and alkali-cationized peptides...
2016: European Journal of Mass Spectrometry
https://www.readbyqxmd.com/read/27869694/the-c-terminal-o-s-acyl-shift-pathway-under-acidic-condition-to-propose-peptide-thioesters
#4
Bo Mi Kim
Peptide-thioester is a pivotal intermediate for peptide ligation and N-, C-terminal cyclization. In this study, desired pathway and the side products of two C-terminal handles, hydroxyethylthiol (HET) and hydroxypropylthiol (HPT) are described in different conditions as well as kinetic studies. In addition, a new mechanism of C-terminal residue racemization is proposed on the basis of differentiation of products derived from the two C-terminal handles in preparing peptide thioesters through an acid-catalyzed tandem thiol switch, first by an intramolecular O-S acyl shift, and then by an intermolecular S-S exchange...
November 17, 2016: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
https://www.readbyqxmd.com/read/27862752/improving-the-binding-affinity-of-in-vitro-evolved-cyclic-peptides-by-inserting-atoms-into-the-macrocycle-backbone
#5
Jonas Wilbs, Simon J Middendorp, Christian Heinis
Cyclic peptides binding to targets of interest can be generated efficiently with powerful in vitro display techniques, such as phage display or mRNA display. The cyclic peptide libraries screened with these methods are generated by altering in a combinatorial fashion the amino acid sequence of the peptides, the number of amino acids in the macrocycle rings, and the cyclization chemistry. A structural element that cannot easily be varied in the cyclic peptides is the backbone, which is built from amino acids, each of which contributes three atoms to the macrocyclic ring structure...
November 11, 2016: Chembiochem: a European Journal of Chemical Biology
https://www.readbyqxmd.com/read/27860140/decarboxylative-peptide-macrocyclization-through-photoredox-catalysis
#6
Stefan J McCarver, Jennifer X Qiao, Joseph Carpenter, Robert M Borzilleri, Michael A Poss, Martin D Eastgate, Michael Miller, David W C MacMillan
A method for the decarboxylative macrocyclization of peptides bearing N-terminal Michael acceptors has been developed. This synthetic method enables the efficient synthesis of cyclic peptides containing γ-amino acids and is tolerant of functionalities present in both natural and non-proteinogenic amino acids. Linear precursors ranging from 3 to 15 amino acids cyclize effectively under this photoredox method. To demonstrate the preparative utility of this method in the context of bioactive molecules, we synthesized COR-005, a somatostatin analogue that is currently in clinical trials...
November 17, 2016: Angewandte Chemie
https://www.readbyqxmd.com/read/27856346/peptidomimetic-therapeutics-scientific-approaches-and-opportunities
#7
REVIEW
Nir Qvit, Samuel J S Rubin, Travis J Urban, Daria Mochly-Rosen, Eric R Gross
Natural endogenously occurring peptides exhibit desirable medicinal properties, but are often limited in application by rapid proteolysis and inadequate membrane permeability. However, editing naturally occurring peptide sequences to develop peptidomimetic analogs created a promising class of therapeutics that can augment or inhibit molecular interactions. Here, we discuss a variety of chemical modifications, including l to d isomerization, cyclization, and unnatural amino acid substitution, as well as design strategies, such as attachment to cell-penetrating peptides, which are used to develop peptidomimetics...
November 14, 2016: Drug Discovery Today
https://www.readbyqxmd.com/read/27849093/a-rapid-and-clean-synthetic-approach-to-cyclic-peptides-via-micro-flow-peptide-chain-elongation-and-photochemical-cyclization-synthesis-of-a-cyclic-rgd-peptide
#8
Yuto Mifune, Hiroyuki Nakamura, Shinichiro Fuse
A cyclic RGD peptide was efficiently synthesized based on micro-flow, triphosgene-mediated peptide chain elongation and micro-flow photochemical macrolactamization. Our approach enabled a rapid (amidation for peptide chain elongation <5 s, macrolactamization <5 min) and clean (only one column chromatographic separation) synthesis of a cyclic peptide.
November 16, 2016: Organic & Biomolecular Chemistry
https://www.readbyqxmd.com/read/27826791/rational-derivation-extension-and-cyclization-of-self-inhibitory-peptides-to-target-tgf-%C3%AE-bmp-signaling-in-onfh
#9
Zhenhong Zhu, Chi Zhang, Wenqi Song
The human transforming growth factor β (TGF-β)/bone morphogenic protein (BMP) signaling has been recognized as an attractive target to suppress fibroblast activation in osteonecrosis of the femoral head (ONFH). Here, we reported successful derivation of a self-inhibitory peptide from the crystal complex interface of TGF-β with its cognate receptor TβRI using rational molecular design and in vitro binding assay. Computational modeling suggested that the peptide possesses a large flexibility and would incur considerable entropy penalty...
November 9, 2016: Amino Acids
https://www.readbyqxmd.com/read/27819351/peplife-a-repository-of-the-half-life-of-peptides
#10
Deepika Mathur, Satya Prakash, Priya Anand, Harpreet Kaur, Piyush Agrawal, Ayesha Mehta, Rajesh Kumar, Sandeep Singh, Gajendra P S Raghava
Short half-life is one of the key challenges in the field of therapeutic peptides. Various studies have reported enhancement in the stability of peptides using methods like chemical modifications, D-amino acid substitution, cyclization, replacement of labile aminos acids, etc. In order to study this scattered data, there is a pressing need for a repository dedicated to the half-life of peptides. To fill this lacuna, we have developed PEPlife (http://crdd.osdd.net/raghava/peplife), a manually curated resource of experimentally determined half-life of peptides...
November 7, 2016: Scientific Reports
https://www.readbyqxmd.com/read/27793068/cyclization-improves-membrane-permeation-by-antimicrobial-peptoids
#11
Konstantin Andreev, Michael W Martynowycz, Andrey Ivankin, Mia L Huang, Ivan Kuzmenko, Mati Meron, Binhua Lin, Kent Kirshenbaum, David Gidalevitz
The peptidomimetic approach has emerged as a powerful tool for overcoming the inherent limitations of natural antimicrobial peptides, where the therapeutic potential can be improved by increasing selectivity and bioavailability. Restraining conformational flexibility of a molecule may reduce the entropy loss upon its binding to the membrane. Experimental findings demonstrate that cyclization of linear antimicrobial peptoids increases their bactericidal activity against Staphylococcus aureus, while maintaining high hemolytic concentrations...
October 28, 2016: Langmuir: the ACS Journal of Surfaces and Colloids
https://www.readbyqxmd.com/read/27791103/structural-elements-of-an-nrps-cyclization-domain-and-its-intermodule-docking-domain
#12
Daniel P Dowling, Yan Kung, Anna K Croft, Koli Taghizadeh, Wendy L Kelly, Christopher T Walsh, Catherine L Drennan
Epothilones are thiazole-containing natural products with anticancer activity that are biosynthesized by polyketide synthase (PKS)-nonribosomal peptide synthetase (NRPS) enzymes EpoA-F. A cyclization domain of EpoB (Cy) assembles the thiazole functionality from an acetyl group and l-cysteine via condensation, cyclization, and dehydration. The PKS carrier protein of EpoA contributes the acetyl moiety, guided by a docking domain, whereas an NRPS EpoB carrier protein contributes l-cysteine. To visualize the structure of a cyclization domain with an accompanying docking domain, we solved a 2...
November 1, 2016: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/27779387/engineering-an-affinity-enhanced-peptide-through-optimization-of-cyclization-chemistry
#13
Chayanon Ngambenjawong, Julio Marco B Pineda, Suzie H Pun
Peptide cyclization is a strategy used to improve stability and/or activity of peptides. The most commonly used cyclization method is disulfide bridge formation of cysteine-containing peptides as typically found in nature. Over the years, an increasing number of alternative chemistries for peptide cyclization with improved efficiency, kinetics, orthogonality, and stability have been reported. However, there has been less appreciation for the opportunity to fine-tune peptide activity via the diverse chemical entities introduced at the site of linkage by different cyclization strategies...
October 25, 2016: Bioconjugate Chemistry
https://www.readbyqxmd.com/read/27752134/the-b1-protein-guides-the-biosynthesis-of-a-lasso-peptide
#14
Shaozhou Zhu, Christopher D Fage, Julian D Hegemann, Andreas Mielcarek, Dushan Yan, Uwe Linne, Mohamed A Marahiel
Lasso peptides are a class of ribosomally synthesized and post-translationally modified peptides (RiPPs) with a unique lariat knot-like fold that endows them with extraordinary stability and biologically relevant activity. However, the biosynthetic mechanism of these fascinating molecules remains largely speculative. Generally, two enzymes (B for processing and C for cyclization) are required to assemble the unusual knot-like structure. Several subsets of lasso peptide gene clusters feature a "split" B protein on separate open reading frames (B1 and B2), suggesting distinct functions for the B protein in lasso peptide biosynthesis...
October 18, 2016: Scientific Reports
https://www.readbyqxmd.com/read/27750005/catalytic-formation-of-disulfide-bonds-in-peptides-by-molecularly-imprinted-microgels-at-oil-water-interfaces
#15
Xiantao Shen, Chuixiu Huang, Sudhirkumar Shinde, Kishore Kumar Jagadeesan, Simon Ekström, Emelie Fritz, Börje Sellergren
This work describes the preparation and investigation of molecularly imprinted polymer (MIP) microgels (MGs) stabilized Pickering emulsions (PE) for their ability to catalyze the formation of disulfide bonds in peptides at the O/W interface. The MIP MGs were synthesized via precipitation polymerization and a programmed initiator change strategy. The MIP MGs were characterized using DLS analysis, SEM measurement and optical microscopy analysis. The dry and wet MIP MGs showed a hydrodynamic diameter of 100 nm and 280 nm, respectively...
October 17, 2016: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/27734922/cellular-uptake-of-a-cystine-knot-peptide-and-modulation-of-its-intracellular-trafficking
#16
Xinxin Gao, Karen Stanger, Harini Kaluarachchi, Till Maurer, Paulina Ciepla, Cecile Chalouni, Yvonne Franke, Rami N Hannoush
Cyclotides or cyclic cystine-knot peptides have emerged as a promising class of pharmacological ligands that modulate protein function. Interestingly, very few cyclotides have been shown to enter into cells. Yet, it remains unknown whether backbone cyclization is required for their cellular internalization. In this report, we studied the cellular behavior of EETI-II, a model acyclic cystine-knot peptide. Even though synthetic methods have been used to generate EETI-II, recombinant methods that allow efficient large scale biosynthesis of EETI-II have been lagging...
October 13, 2016: Scientific Reports
https://www.readbyqxmd.com/read/27718641/discovery-and-optimization-of-peptide-macrocycles
#17
Andrew M White, David J Craik
Macrocyclic peptides are generally more resistant to proteolysis and often have higher potency than linear peptides and so they are excellent leads in drug design. Their study is significant because they offer potential as a new generation of drugs that are potent and specific, and thus might have fewer side effects than traditional small molecule drugs. Areas covered: This article covers macrocyclic drug leads based on nature-derived cyclic peptides as well as synthetic cyclic peptides and close derivatives...
October 10, 2016: Expert Opinion on Drug Discovery
https://www.readbyqxmd.com/read/27714610/ribosomal-synthesis-of-thioether-bridged-bicyclic-peptides
#18
Nina Bionda, Rudi Fasan
Many biologically active peptides found in nature exhibit a bicyclic structure wherein a head-to-tail cyclic backbone is further constrained by an intramolecular linkage connecting two side chains of the peptide. Accordingly, methods to access macrocyclic peptides sharing this overall topology could be of significant value toward the discovery of new functional entities and bioactive compounds. With this goal in mind, we recently developed a strategy for enabling the biosynthesis of thioether-bridged bicyclic peptides in living bacterial cells...
2017: Methods in Molecular Biology
https://www.readbyqxmd.com/read/27714608/intracellular-production-of-cyclic-peptide-libraries-with-siclopps
#19
Eliot L Osher, Ali Tavassoli
Cyclic peptides are an important class of molecules that are increasingly viewed as an ideal scaffold for inhibition of protein-protein interactions (PPI). Here we detail an approach that enables the intracellular synthesis of cyclic peptide libraries of around 10(8) members. The method utilizes split intein mediated circular ligation of peptides and proteins (SICLOPPS), taking advantage of split intein splicing to cyclize a library of peptide sequences. SICLOPPS allows the ring size, set residues and number of random residues within a library to be predetermined by the user...
2017: Methods in Molecular Biology
https://www.readbyqxmd.com/read/27714190/solid-phase-synthesis-and-fluorine-18-radiolabeling-of-cyclorgdyk
#20
Ryan A Davis, Kevin Lau, Sven H Hausner, Julie L Sutcliffe
Solid-phase peptide synthesis, head-to-tail cyclization, and subsequent radiolabeling provided a reproducible, simple, rapid synthetic method to generate the cyclic peptide radiotracer cRGDyK([(18)F]FBA). Herein is reported the first on-resin cyclization and (18)F-radiolabeling of a cyclic peptide (cRGDyK) in an overall peptide synthesis yield of 88% (cRGDyK(NH2)) and subsequent radiolabeling yield of 14 ± 2% (decay corrected, n = 4). This approach is generally applicable to the development of an automated process for the synthesis of cyclic radiolabeled peptides for positron emission tomography (PET)...
September 21, 2016: Organic & Biomolecular Chemistry
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