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Unnatural amino acid

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https://www.readbyqxmd.com/read/28636281/aryl-and-heteroaryl-substituted-phenylalanines-as-ampa-receptor-ligands
#1
Ewa Szymańska, Paulina Chałupnik, Tommy N Johansen, Birgitte Nielsen, Ana Maria Cuñado Moral, Darryl S Pickering, Anna Więckowska, Katarzyna Kieć-Kononowicz
A series of racemic unnatural amino acids was rationally designed on the basis of recently published X-ray structures of the GluA2 LBD with bound phenylalanine-based antagonists. Twelve new diaryl- or aryl/heteroaryl-substituted phenylalanine derivatives were synthesized and evaluated in vitro in radioligand binding assays at native rat ionotropic glutamate receptors. The most interesting compound in this series, (RS)-2-amino-3-(3'-hydroxy-5-(1H-pyrazol-4-yl)-[1,1'-biphenyl]-3-yl)propanoic acid 7e, showed the binding affinity of 4...
June 21, 2017: Chemical Biology & Drug Design
https://www.readbyqxmd.com/read/28634827/highly-functionalized-cyclic-%C3%AE-amino-acid-moieties-as-promising-scaffolds-in-peptide-research-and-drug-design
#2
REVIEW
Loránd Kiss, István M Mándity, Ferenc Fülöp
Peptide-based drug research has received high attention in the field of medicinal chemistry over the past decade. For drug design, to improve proteolytic stability, it is desirable to include unnatural building blocks, such as conformationally restricted β-amino acid moieties, into the peptide sequence. Accordingly, the synthesis and incorporation of such conformationally rigid systems into novel type of peptides has gained large interest. Our research group has designed highly efficient methods for the construction of potential antimicrobial peptides...
May 30, 2017: Amino Acids
https://www.readbyqxmd.com/read/28608946/genetic-encoding-of-photocaged-tyrosines-with-improved-light-activation-properties-for-the-optical-control-of-protease-function
#3
Ji Luo, Jessica Torres-Kolbus, Jihe Liu, Alexander Deiters
We genetically encoded three new caged tyrosine analogues with improved photochemical properties by using an engineered pyrrolysyl-tRNA synthetase/tRNACUA pair in bacterial and mammalian cells. We applied the new tyrosine analogues to the photoregulation of firefly luciferase by caging its key tyrosine residue, Tyr340, and observed excellent off-to-on light switching. This reporter was then used to evaluate the activation rates of the different light-removable protecting groups in live cells. We identified the nitropiperonyl caging group as an excellent compromise between incorporation efficiency and photoactivation properties...
June 13, 2017: Chembiochem: a European Journal of Chemical Biology
https://www.readbyqxmd.com/read/28605379/voltage-clamp-fluorometry-in-xenopus-oocytes-using-fluorescent-unnatural-amino-acids
#4
Tanja Kalstrup, Rikard Blunck
Voltage-Clamp Fluorometry (VCF) has been the technique of choice to investigate the structure and function of electrogenic membrane proteins where real-time measurements of fluorescence and currents simultaneously report on local rearrangements and global function, respectively(1). While high-resolution structural techniques such as cryo-electron microscopy or X-ray crystallography provide static images of the proteins of interest, VCF provides dynamic structural data that allows us to link the structural rearrangements (fluorescence) to dynamic functional data (electrophysiology)...
May 27, 2017: Journal of Visualized Experiments: JoVE
https://www.readbyqxmd.com/read/28603976/%C3%AE-imino-esters-in-organic-synthesis-recent-advances
#5
Bagher Eftekhari-Sis, Maryam Zirak
α-Imino esters are useful precursors for the synthesis of a variety of types of natural and unnatural α-amino acid derivatives, with a wide range of biological activities. Due to the adjacent ester group, α-imino esters are more reactive relative to other types of imines and undergo different kinds of reactions, including organometallics addition, metal catalyzed vinylation and alkynylation, aza-Henry, aza-Morita-Baylis-Hillman, imino-ene, Mannich-type, and cycloaddition reactions, as well as hydrogenation and reduction...
June 12, 2017: Chemical Reviews
https://www.readbyqxmd.com/read/28576486/construction-of-an-inducible-stable-cell-line-for-efficient-incorporation-of-unnatural-amino-acids-in-mammalian-cells
#6
Ziwei Zhang, Huan Xu, Longlong Si, Yi Chen, Bo Zhang, Yan Wang, Yiming Wu, Xueying Zhou, Lihe Zhang, Demin Zhou
The genetic incorporation of unnatural amino acids (Uaas) with defined properties into proteins at designated sites represents an extremely powerful tool for protein engineering. However, the efficient incorporation of Uaas in response to the amber stop codon in mammalian cells remains a substantial challenge due to the competition from release factor 1(RF1). Addressing this challenge will greatly broaden the power and scope of this technology. Here, we chose the eRF1 mutant, which can selectively enhance Uaa incorporation in response to the amber codon without increasing the readthrough of the opal and ochre codons...
May 31, 2017: Biochemical and Biophysical Research Communications
https://www.readbyqxmd.com/read/28566650/a-convenient-method-for-preparation-of-%C3%AE-imino-carboxylic-acid-derivatives-and-application-to-the-asymmetric-synthesis-of-unnatural-%C3%AE-amino-acid-derivative
#7
Tsubasa Inokuma, Takahisa Jichu, Kodai Nishida, Akira Shigenaga, Akira Otaka
We describe herein a manganese(IV) oxide-mediated oxidation of N-p-methoxyphenyl (PMP)-protected glycine derivatives for the synthesis of α-imino carboxylic acid derivatives. Using this methodology, utilization of unstable glyoxic acid derivatives was avoided. Furthermore, using this methodology we synthesized novel α-imino carboxylic acid derivatives such as α-imino phenyl ester, perfluoroalkyl etsers, imides, and thioester. The asymmetric Mannich reaction of those novel imine derivatives with 1,3-dicarbonyl compound is also described, and the novel α-imino imide gave improved chemical yield and stereoselectivity compared with those obtained by the use of the conventional α-imino ester-type substrate...
2017: Chemical & Pharmaceutical Bulletin
https://www.readbyqxmd.com/read/28533567/synthesis-and-incorporation-of-a-caged-tyrosine-amino-acid-possessing-a-bioorthogonal-handle
#8
Marshall S Padilla, Christopher A Farley, Lindsay E Chatkewitz, Douglas D Young
Reversing a bioconjugation in a spatial and temporal fashion has widespread applications, especially toward targeted drug delivery. We report the synthesis and incorporation of an unnatural amino acid with an alkyne modified dimethoxy-ortho-nitrobenzyl caging group. This unnatural amino acid can be utilized in a Glaser-Hay conjugation to generate a bioconjugate, but also is able to disrupt the bioconjugate when irradiated with light. These combined features allow for the preparation of bioconjugates with a high degree of site-specificity and allow for the separation of the two components if necessary...
October 19, 2016: Tetrahedron Letters
https://www.readbyqxmd.com/read/28522372/effective-antimicrobial-activity-of-a-peptide-mutant-cbf-14-2-against-penicillin-resistant-bacteria-based-on-its-unnatural-amino-acids
#9
Wei Kang, Hanhan Liu, Lingman Ma, Mengxiao Wang, Shanshan Wei, Pengbo Sun, Meiling Jiang, Min Guo, Changlin Zhou, Jie Dou
Broad spectrum activities, a unique mode of actions and rare resistant variants make antimicrobial peptide (AMP) a potential alternative to antibiotics. However, AMPs still have limitations in clinical development due to their physiological stability, toxicity and manufacturing costs. Cbf-14, derived from cathelicidin-BF has been proven to be effective against drug-resistant bacteria. Herein, a series of Cbf-14 mutants were designed to overcome these limitations. Design strategies included substitutions of lysine (Lys) or leucine (Leu) with similar residues such as ornithine (Orn) and norleucine (Ile), which are unnatural amino acids, to generate AMPs with enhanced therapeutic potential...
May 15, 2017: European Journal of Pharmaceutical Sciences
https://www.readbyqxmd.com/read/28522266/site-specific-conjugation-of-fibroblast-growth-factor-2-fgf2-based-on-incorporation-of-alkyne-reactive-unnatural-amino-acid
#10
K W Swiderska, A Szlachcic, A Czyrek, M Zakrzewska, J Otlewski
Recent advances in site-specific protein modification include the increasingly popular incorporation of unnatural amino acid(s) using amber codon, a method developed by Schultz and coworkers. In this study, we employ this technique to introduce propargyllysine (PrK) in human fibroblast growth factor 2 (FGF2). Owing to an alkyne moiety in its side chain, PrK is compatible with Cu(I)-catalyzed azide-alkyne 1,3-dipolar cycloaddition (CuAAC). We successfully tested CuAAC-mediated conjugation of FGF2 with two compounds - a fluorophore carboxyrhodamine 110 or a cytotoxic drug monomethyl auristatin E (MMAE)...
May 5, 2017: Bioorganic & Medicinal Chemistry
https://www.readbyqxmd.com/read/28507719/broad-substrate-tolerance-of-tubulin-tyrosine-ligase-enables-one-step-site-specific-enzymatic-protein-labeling
#11
Dominik Schumacher, Oliver Lemke, Jonas Helma, Lena Gerszonowicz, Verena Waller, Tina Stoschek, Patrick M Durkin, Nediljko Budisa, Heinrich Leonhardt, Bettina G Keller, Christian P R Hackenberger
The broad substrate tolerance of tubulin tyrosine ligase is the basic rationale behind its wide applicability for chemoenzymatic protein functionalization. In this context, we report that the wild-type enzyme enables ligation of various unnatural amino acids that are substantially bigger than and structurally unrelated to the natural substrate, tyrosine, without the need for extensive protein engineering. This unusual substrate flexibility is due to the fact that the enzyme's catalytic pocket forms an extended cavity during ligation, as confirmed by docking experiments and all-atom molecular dynamics simulations...
May 1, 2017: Chemical Science
https://www.readbyqxmd.com/read/28498103/a-selectivity-filter-at-the-intracellular-end-of-the-acid-sensing-ion-channel-pore
#12
Timothy Lynagh, Emelie Flood, Céline Boiteux, Matthias Wulf, Vitaly V Komnatnyy, Janne M Colding, Toby W Allen, Stephan A Pless
Increased extracellular proton concentrations during neurotransmission are converted to excitatory sodium influx by acid-sensing ion channels (ASICs). 10-fold sodium/potassium selectivity in ASICs has long been attributed to a central constriction in the channel pore, but experimental verification is lacking due to the sensitivity of this structure to conventional manipulations. Here, we explored the basis for ion selectivity by incorporating unnatural amino acids into the channel, engineering channel stoichiometry and performing free energy simulations...
May 12, 2017: ELife
https://www.readbyqxmd.com/read/28487404/long-range-proton-coupled-electron-transfer-in-the-escherichia-coli-class-ia-ribonucleotide-reductase
#13
REVIEW
Steven Y Reece, Mohammad R Seyedsayamdost
Escherichia coli class Ia ribonucleotide reductase (RNR) catalyzes the conversion of nucleotides to 2'-deoxynucleotides using a radical mechanism. Each turnover requires radical transfer from an assembled diferric tyrosyl radical (Y•) cofactor to the enzyme active site over 35 Å away. This unprecedented reaction occurs via an amino acid radical hopping pathway spanning two protein subunits. To study the mechanism of radical transport in RNR, a suite of biochemical approaches have been developed, such as site-directed incorporation of unnatural amino acids with altered electronic properties and photochemical generation of radical intermediates...
May 9, 2017: Essays in Biochemistry
https://www.readbyqxmd.com/read/28485427/chemoenzymatic-synthesis-of-polypeptides-containing-the-unnatural-amino-acid-2-aminoisobutyric-acid
#14
Kousuke Tsuchiya, Keiji Numata
Polypeptides containing 2-aminoisobutyric acid (Aib) units as an unnatural amino acid residue were synthesized by papain-catalyzed chemoenzymatic polymerization of a tripeptide ethyl ester l-Ala-Aib-l-Ala-OEt in an aqueous medium. The Aib-containing polypeptide adopted an α-helix conformation in both the solid and solution phases, which was induced by the periodic Aib residue.
May 9, 2017: Chemical Communications: Chem Comm
https://www.readbyqxmd.com/read/28481537/designing-peptide-and-protein-modified-hydrogels-selecting-the-optimal-conjugation-strategy
#15
Stephanie A Fisher, Alexander E G Baker, Molly S Shoichet
Hydrogels are used in a wide variety of biomedical applications including tissue engineering, biomolecule delivery, cell delivery, and cell culture. These hydrogels are often designed with a specific biological function in mind, requiring the chemical incorporation of bioactive factors to either mimic extracellular matrix or to deliver a payload to diseased tissue. Appropriate synthetic techniques to ligate bioactive factors, such as peptides and proteins, onto hydrogels are critical in designing materials with biological function...
June 7, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28480699/right-handed-helical-foldamers-consisting-of-de-novo-d-aapeptides
#16
Peng Teng, Ning Ma, Darrell Cole Cerrato, Fengyu She, Timothy Odom, Xiang Wang, Li-June Ming, Arjan van der Vaart, Lukasz Wojtas, Hai Xu, Jianfeng Cai
New types of foldamer scaffolds are formidably challenging to design and synthesize, yet highly desirable as structural mimics of peptides/proteins with a wide repertoire of functions. In particular, the development of peptidomimetic helical foldamers holds promise for new biomaterials, catalysts, and drug molecules. Unnatural l-sulfono-γ-AApeptides were recently developed and shown to have potential applications in both biomedical and material sciences. However, d-sulfono-γ-AApeptides, the enantiomers of l-sulfono-γ-AApeptides, have never been studied due to the lack of high-resolution three-dimensional structures to guide structure-based design...
May 16, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28471671/quantifying-biomolecular-recognition-with-site-specific-2d-infrared-probes
#17
Philip J M Johnson, Klemens L Koziol, Peter Hamm
Azidohomoalanine (Aha) is an unnatural amino acid containing an infrared active azido side chain group that can, through frequency shifts of the azido stretch vibration, act as a probe of local structure. To realize the potential of such structural probes for protein science, we have developed a two-dimensional infrared spectrometer employing fast mechanical scanning and intrinsic phasing of the resulting spectra, leading to a lower sensitivity limit of ∼100 μOD level samples. Using this approach, we quantify the biomolecular recognition between a PDZ2 domain and two Aha-mutated peptides...
May 8, 2017: Journal of Physical Chemistry Letters
https://www.readbyqxmd.com/read/28463513/characterization-of-the-polymyxin-d-synthetase-biosynthetic-cluster-and-product-profile-of-paenibacillus-polymyxa-atcc-10401
#18
Charles A Galea, Meiling Han, Yan Zhu, Kade Roberts, Jiping Wang, Philip E Thompson, Jian L, Tony Velkov
The increasing prevalence of polymyxin-resistant bacteria has stimulated the search for improved polymyxin lipopeptides. Here we describe the sequence and product profile for polymyxin D nonribosomal peptide synthetase from Paenibacillus polymyxa ATCC 10401. The polymyxin D synthase gene cluster comprised five genes that encoded ABC transporters (pmxC and pmxD) and enzymes responsible for the biosynthesis of polymyxin D (pmxA, pmxB, and pmxE). Unlike polymyxins B and E, polymyxin D contains d-Ser at position 3 as opposed to l-α,γ-diaminobutyric acid and has an l-Thr at position 7 rather than l-Leu...
May 2, 2017: Journal of Natural Products
https://www.readbyqxmd.com/read/28454062/self-assembled-dehydropeptide-nano-carriers-for-delivery-of-ornidazole-and-curcumin
#19
Smriti Rekha Deka, Santosh Yadav, Dheeresh Kumar, Sumit Garg, Manohar Mahato, Ashwani Kumar Sharma
In the recent studies, it has been demonstrated that incorporation of unnatural amino acid, α,β-dehydrophenylalanine, in small peptides results in stable self-assembled nanostructures with different sizes and shapes. Here, we have replaced the natural amino acid, phenylalanine, from our earlier reported work on self-assembled peptide, Boc-Pro-Phe-Gly-OMe, with a constrained dehydro amino acid, α,β-dehydrophenylalanine, to study its influence on self-assembled nanostructures. Dehydrotripeptide, Boc-Pro-ΔPhe-Gly-OMe, self-assembled into nanostructures in aqueous solutions and formed hydrophobic matrix with improved encapsulation efficiency of hydrophobic molecules...
April 20, 2017: Colloids and Surfaces. B, Biointerfaces
https://www.readbyqxmd.com/read/28453915/documenting-and-harnessing-the-biological-potential-of-molecules-in-distributed-drug-discovery-d3-virtual-catalogs
#20
Milata M Abraham, Ryan E Denton, Richard W Harper, William L Scott, Martin J O'Donnell, Jacob D Durrant
Virtual molecular catalogs have limited utility if member compounds are (1) difficult to synthesize or (2) unlikely to have biological activity. The Distributed Drug Discovery (D3) program addresses the synthesis challenge by providing scientists with a free virtual D3 catalog of 73,024 easy-to-synthesize N-acyl unnatural α-amino acids, their methyl esters, and primary amides. The remaining challenge is to document and exploit the bioactivity potential of these compounds. In the current work, a search process is described that retrospectively identifies all virtual D3 compounds classified as bioactive hits in PubChem-cataloged experimental assays...
April 28, 2017: Chemical Biology & Drug Design
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