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cyclization peptides

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https://www.readbyqxmd.com/read/28230996/a-facile-n-mercaptoethoxyglycinamide-mega-linker-ap-proach-to-peptide-thioesterification-and-cyclization
#1
Patrick M M Shelton, Caroline E Weller, Champak Chatterjee
The C-terminal selective electrophilic activation of polypeptides is essential for site-specific peptide mod-ification and conjugation techniques such as Native Chemi-cal Ligation (NCL). Peptide C-terminal α-thioesters are par-ticularly valuable precursors for NCL, due to their hydrolytic stability in aqueous buffers and reactivity toward thiol nucle-ophiles. The synthesis of peptide α-thioesters, however, re-quires harsh acidic conditions or complex chemical manipu-lations, which ultimately limits their functional group com-patibility and broad utility...
February 23, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28222263/reaction-mechanism-of-covalent-modification-of-phosphatidylethanolamine-lipids-by-reactive-aldehydes-4-hydroxy-2-nonenal-and-4-oxo-2-nonenal
#2
Katarina Vazdar, Danijela Vojta, Davor Margetić, Mario Vazdar
4-hydroxy-2-nonenal (HNE) and 4-oxo-2-nonenal (ONE) are biologically important reactive aldehydes formed during oxidative stress in phospholipid bilayers. They are highly reactive species due to presence of several reaction centers and can react with amino acids in peptides and proteins, as well as phosphoethanolamine (PE) lipids, thus modifying their biological activity. The aim of this work is to study in a molecular detail the reactivity of HNE and ONE towards PE lipids in a simplified system containing only lipids and reactive aldehydes in dichloromethane as an inert solvent...
February 21, 2017: Chemical Research in Toxicology
https://www.readbyqxmd.com/read/28218515/chlorinated-glycopeptide-antibiotic-peptide-precursors-improve-cytochrome-p450-catalyzed-cyclization-cascade-efficiency
#3
Madeleine Peschke, Clara Brieke, Rob Goode, Ralf Schittenhelm, Max J Cryle
The activity of glycopeptide antibiotics depends upon important structural modifications to their precursor heptapeptide backbone: specifically, the Cytochrome P450-catalyzed oxidative crosslinking of aromatic side chains as well as the halogenation of specific residues within the peptide. The timing of halogenation and its effect on the cyclization of the peptide is currently unclear. Our results show that chlorination of peptide precursors improves their processing by P450 enzymes in vitro, which provides support for GPA halogenation occurring prior to peptide cyclization during non-ribosomal peptide synthesis...
February 20, 2017: Biochemistry
https://www.readbyqxmd.com/read/28212041/simultaneous-cyclization-and-derivatization-of-peptides-using-cyclopentenediones
#4
Omar Brun, Lewis J Archibald, Jordi Agramunt, Enrique Pedroso, Anna Grandas
Unprotected linear peptides containing N-terminal cysteines and another cysteine residue can be simultaneously cyclized and derivatized using 2,2-disubstituted cyclopentenediones. High yields of cyclic peptide conjugates may be obtained in short reaction times using only a slight excess of the cyclopentenedione moiety under TEMPO catalysis and in the presence of LiCl.
February 17, 2017: Organic Letters
https://www.readbyqxmd.com/read/28191919/lysine-tryptophan-crosslinked-peptides-produced-by-radical-sam-enzymes-in-pathogenic-streptococci
#5
Kelsey R Schramma, Mohammad R Seyedsayamdost
Macrocycles represent a common structural framework in many naturally-occurring peptides. Several strategies exist for macrocyclization, and the corresponding enzymes are of great interest, as they enhance our repertoire for creating complex molecules. We recently discovered a new peptide cyclization reaction involving a crosslink between the side-chains of lysine and tryptophan that is installed by a radical SAM enzyme. Herein, we characterize relatives of this metalloenzyme from the pathogens Streptococcus agalactiae and Streptococcus suis...
February 13, 2017: ACS Chemical Biology
https://www.readbyqxmd.com/read/28165720/intein-promoted-cyclization-of-aspartic-acid-flanking-the-intein-leads-to-atypical-n-terminal-cleavage
#6
Christopher J Minteer, Nicolle M Siegart, Kathryn M Colelli, Xinyue Liu, Robert J Linhardt, Chunyu Wang, Alvin V Gomez, Julie N Reitter, Kenneth V Mills
Protein splicing is a post-translational reaction facilitated by an intein, or intervening protein, which involves the removal of the intein and the ligation of the flanking polypeptides, or exteins. A DNA polymerase II intein from Pyrococcus abyssi (Pab PolII intein) can promote protein splicing in vitro on incubation at high temperature. Mutation of active site residues Cys1, Gln185, and Cys+1 to Ala results in an inactive intein precursor, which cannot promote the steps of splicing, including cleavage of the peptide bond linking the N-extein and intein (N-terminal cleavage)...
February 15, 2017: Biochemistry
https://www.readbyqxmd.com/read/28165293/anticancer-activities-of-bovine-and-human-lactoferricin-derived-peptides
#7
Mauricio Arias, Ashley L Hilchie, Evan F Haney, Jan G M Bolscher, M Eric Hyndman, Robert E W Hancock, Hans J Vogel
Lactoferrin (LF) is a mammalian host defense glycoprotein with diverse biological activities. Peptides derived from the cationic region of LF possess cytotoxic activity against cancer cells in vitro and in vivo. Bovine lactoferricin (LFcinB), a peptide derived from bovine LF (bLF), exhibits broad-spectrum anticancer activity, while a similar peptide derived from human LF (hLF) is not as active. In this work, several peptides derived from the N-terminal regions of bLF and hLF were studied for their anticancer activities against leukemia and breast-cancer cells, as well as normal peripheral blood mononuclear cells...
February 2017: Biochemistry and Cell Biology, Biochimie et Biologie Cellulaire
https://www.readbyqxmd.com/read/28153544/post-translationally-modified-frog-skin-derived-antimicrobial-peptides-are-effective-against-aeromonas-sobria
#8
Vineethkumar Tv, Asha R, Shyla G, Sanil George
Antimicrobial peptides (brevinin1 HYba1 and brevinin1 HYba2) identified from the skin secretion of an endemic frog species of Western Ghats were studied against fish pathogens. Post-translational modifications such as c-terminal amidation and cyclization of the peptides were enhanced on the activity against Aeromonas sobria. Based on the Minimum inhibitory concentration (3 μM), cyclic amidated brevinin Hyba2 was identified as the most promising antimicrobial agent against A. sobria and can be developed further as a lead drug molecule...
January 30, 2017: Microbial Pathogenesis
https://www.readbyqxmd.com/read/28151653/full-sequence-amino-acid-scanning-of-%C3%AE-defensin-rtd-1-yields-a-potent-anthrax-lethal-factor-protease-inhibitor
#9
Yilong Li, Andrew Gould, Teshome Aboye, Tao Bi, Leonard Breindel, Alexander Shekhtman, Julio A Camarero
θ-Defensin RTD-1 is a noncompetitive inhibitor of anthrax lethal factor (LF) protease (IC50 = 390 ± 20 nM, Ki = 365 ± 20 nM) and a weak inhibitor of other mammalian metalloproteases such as TNFα converting enzyme (TACE) (Ki = 4.45 ± 0.48 μM). Using full sequence amino acid scanning in combination with a highly efficient "one-pot" cyclization-folding approach, we obtained an RTD-1-based peptide that was around 10 times more active than wild-type RTD-1 in inhibiting LF protease (IC50 = 43 ± 3 nM, Ki = 18 ± 1 nM)...
February 14, 2017: Journal of Medicinal Chemistry
https://www.readbyqxmd.com/read/28148910/intein-mediated-backbone-cyclization-of-vp1-protein-enhanced-protection-of-cvb3-induced-viral-myocarditis
#10
Xingmei Qi, Sidong Xiong
CVB3 is a common human pathogen to be highly lethal to newborns and causes viral myocarditis and pancreatitis in adults. However, there is no vaccine available for clinical use. CVB3 capsid protein VP1 is an immunodominant structural protein, containing several B- and T-cell epitopes. However, immunization of mice with VP1 protein is ineffective. Cyclization of peptide is commonly used to improve their in vivo stability and biological activity. Here, we designed and synthesizd cyclic VP1 protein by using engineered split Rma DnaB intein and the cyclization efficiency was 100% in E...
February 2, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28135077/mechanistic-understanding-of-lanthipeptide-biosynthetic-enzymes
#11
Lindsay M Repka, Jonathan R Chekan, Satish K Nair, Wilfred A van der Donk
Lanthipeptides are ribosomally synthesized and post-translationally modified peptides (RiPPs) that display a wide variety of biological activities, from antimicrobial to antiallodynic. Lanthipeptides that display antimicrobial activity are called lantibiotics. The post-translational modification reactions of lanthipeptides include dehydration of Ser and Thr residues to dehydroalanine and dehydrobutyrine, a transformation that is carried out in three unique ways in different classes of lanthipeptides. In a cyclization process, Cys residues then attack the dehydrated residues to generate the lanthionine and methyllanthionine thioether cross-linked amino acids from which lanthipeptides derive their name...
January 30, 2017: Chemical Reviews
https://www.readbyqxmd.com/read/28132916/characterization-of-ligand-binding-to-melanocortin-4-receptors-using-fluorescent-peptides-with-improved-kinetic-properties
#12
Reet Link, Santa Veiksina, Ago Rinken, Sergei Kopanchuk
Melanocortin 4 (MC4) receptors are important drug targets as they regulate energy homeostasis, eating behaviour and sexual functions. The ligand binding process to these G protein-coupled receptors is subject to considerable complexity. Different steps in the complex dynamic regulation can be characterized by ligand binding kinetics. Optimization of these kinetic parameters in terms of on-rate and residence time can increase the rapid onset of drug action and reduce off-target effects. Fluorescence anisotropy (FA) is one of the homogeneous fluorescence-based assays that enable continuous online monitoring of ligand binding kinetics...
January 26, 2017: European Journal of Pharmacology
https://www.readbyqxmd.com/read/28122173/structure-based-derivation-of-peptide-inhibitors-to-target-tgf-%C3%AE-1-receptor-for-the-suppression-of-hypertrophic-scarring-fibroblast-activation
#13
Huan Hu, Songlin Yang, Jianghong Zhang, Guangyu Mao
The intermolecular recognition and interaction between human transforming growth factor β-1 (TGF-β1) and its cognate receptor TβRII have been implicated in the pathological condition of hypertrophic scarring (HS). Here, we attempted to rationally derive peptide inhibitors from the complex interface of TGF-β1 with TβRII to disrupt such interaction for the suppression of fibroblast activation involved in HS. A synthetic strategy that integrated computational design and fluorescence-based assay was described to examine the structural basis and energetic property of TGF-β1-TβRII crystal structure, from which a small peptide segment in the complex binding site was stripped artificially...
January 25, 2017: Chemical Biology & Drug Design
https://www.readbyqxmd.com/read/28096492/identification-of-glutaminyl-cyclase-genes-involved-in-pyroglutamate-modification-of-fungal-lignocellulolytic-enzymes
#14
Vincent W Wu, Craig M Dana, Anthony T Iavarone, Douglas S Clark, N Louise Glass
: The breakdown of plant biomass to simple sugars is essential for the production of second-generation biofuels and high-value bioproducts. Currently, enzymes produced from filamentous fungi are used for deconstructing plant cell wall polysaccharides into fermentable sugars for biorefinery applications. A post-translational N-terminal pyroglutamate modification observed in some of these enzymes occurs when N-terminal glutamine or glutamate is cyclized to form a five-membered ring. This modification has been shown to confer resistance to thermal denaturation for CBH-1 and EG-1 cellulases...
January 17, 2017: MBio
https://www.readbyqxmd.com/read/28077796/tumor-cell-migration-is-inhibited-by-a-novel-therapeutic-strategy-antagonizing-the-alpha-7-receptor
#15
Chris Pepper, Henry Tu, Paul Morrill, Sara Garcia-Rates, Chris Fegan, Susan Greenfield
A 14mer peptide (T14) derived from the C-terminus of acetylcholinesterase (AChE) selectively activates metastatic breast cancer cells via the alpha-7 nicotinic receptor (α7 nAChR). This naturally occurring peptide is also present in brain, is elevated in Alzheimer's disease, and is antagonised by a cyclized variant (NBP-14). Here we investigated the effects of NBP-14 in six different cancer cell lines, primary leukemia B-cells and normal B-cells. All cells tested expressed α7 nAChR, intracellular and extracellular T14...
January 6, 2017: Oncotarget
https://www.readbyqxmd.com/read/28074955/total-synthesis-and-biological-activity-of-dolastatin-16
#16
Loida O Casalme, Arisa Yamauchi, Akinori Sato, Julie G Petitbois, Yasuyuki Nogata, Erina Yoshimura, Tatsufumi Okino, Taiki Umezawa, Fuyuhiko Matsuda
The total synthesis of dolastatin 16, a macrocyclic depsipeptide first isolated from the sea hare Dolabella auricularia as a potential antineoplastic metabolite by Pettit et al., was achieved in a convergent manner. Dolastatin 16 was reported by Tan to exhibit strong antifouling activity, and thus shows promise for inhibiting the attachment of marine benthic organisms such as Amphibalanus amphitrite to ships and submerged artificial structures. Therefore, dolastatin 16 is a potential compound for a new, environmentally friendly antifouling material to replace banned tributyltin-based antifouling paints...
February 1, 2017: Organic & Biomolecular Chemistry
https://www.readbyqxmd.com/read/28065500/activation-of-lysine-specific-demethylase-1-inhibitor-peptide-by-redox-controlled-cleavage-of-a-traceless-linker
#17
Yuichi Amano, Naoki Umezawa, Shin Sato, Hisami Watanabe, Takashi Umehara, Tsunehiko Higuchi
We have previously employed cyclization of a linear peptide as a strategy to modulate peptide function and properties, but cleavage to regenerate the linear peptide left parts of the linker structure on the peptide, interfering with its activity. Here, we focused on cyclization of a linear peptide via a "traceless" disulfide-based linkage that would be cleaved and completely removed in a reducing environment, regenerating the original linear peptide without any linker-related structure. Thus, the linker would serve as a redox switch that would be activated in the intracellular environment...
December 23, 2016: Bioorganic & Medicinal Chemistry
https://www.readbyqxmd.com/read/28029647/peptide-guided-targeting-of-gpr55-for-anti-cancer-therapy
#18
Maria Mangini, Enrico Iaccino, Maria Giovanna Mosca, Selena Mimmi, Rosa D'Angelo, Ileana Quinto, Giuseppe Scala, Stefania Mariggiò
Expression of the lysophosphatidylinositol receptor GPR55 correlates with invasive potential of metastatic cells and bone metastasis formation of different types of tumors. These findings suggest a role for GPR55 signaling in cancer progression, including in lymphoproliferative diseases. Here, we screened a M13-phage-displayed random library using the bait of HEK293 cells that heterologously expressed full-length HA-GPR55. We selected a set of phagotopes that carried 7-mer insert peptides flanked by a pair of cysteine residues, which resulted in cyclized peptides...
December 23, 2016: Oncotarget
https://www.readbyqxmd.com/read/28013146/rational-design-of-cyclic-peptides-to-disrupt-tgf-%C3%AE-smad7-signaling-in-heterotopic-ossification
#19
Biao Zhong, Chi Zhang, Shang Guo, Changqing Zhang
The human TGF-β/SMAD7 signaling has been recognized as an attractive target of heterotopic ossification (HO). Here, we report a successful rational design of cyclic peptides to disrupt the signaling pathway by targeting TGF-β-receptor complex. The intermolecular interaction between TGF-β and its cognate receptor is characterized in detail using molecular dynamics simulation, binding energetic analysis, and alanine scanning. With the computational analysis a binding loop of receptor protein is identified that plays an essential role in the peptide-mediated TGF-β-receptor interaction...
December 7, 2016: Journal of Molecular Graphics & Modelling
https://www.readbyqxmd.com/read/27982494/polar-hinges-as-functionalized-conformational-constraints-in-bi-cyclic-peptides
#20
Helmus van de Langemheen, Valerijs Korotkovs, Joachim Bijl, Claire Wilson, Sangram S Kale, Christian Heinis, Rob M J Liskamp
Two polar hinges for cyclization of peptides have been developed, leading to bicyclic peptides and cyclized peptides with improved solubility and biological activity. Increasingly, we note that a good aqueous solubility of peptides is an absolute prerequisite, not only to allow handling and purification of our target peptides but also being crucial for biological activity characteristics. Compared to earlier hinges, the 1,1',1"-(1,3,5-triazinane-1,3,5-triyl)tris(2-bromoethanone) (TATB) and 2,4,6-tris(bromomethyl)-s-triazine (TBMT), each containing three nitrogen atoms are structurally similar but chemically very different...
December 16, 2016: Chembiochem: a European Journal of Chemical Biology
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