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Covalent labeling

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https://www.readbyqxmd.com/read/28530188/simple-assay-for-screening-phytoestrogenic-compounds-using-the-oestrogen-receptor-immobilised-magnetite-nanoparticles
#1
Pimchanok Busayapongchai, Sineenat Siri
With increasing interests of phytoestrogens for their potential applications, a rapid and simple tool for screening these phytochemicals is still required. In this study, a simple assay to detect phytoestrogens was developed based on the competition binding between the tested samples and the fluorescently labelled oestrogen (E2) to the human ligand binding domain of oestrogen receptor (LBD-ER) that was immobilised on the magnetite nanoparticles (MNPs). The 40-kDa LBD-ER peptide was produced in an Escherichia coli system...
June 2017: IET Nanobiotechnology
https://www.readbyqxmd.com/read/28525848/an-amplified-comparative-fluorescence-resonance-energy-transfer-immunosensing-of-ca125-tumor-marker-and-ovarian-cancer-cells-using-green-and-economic-carbon-dots-for-bio-applications-in-labeling-imaging-and-sensing
#2
Somayeh Hamd-Ghadareh, Abdollah Salimi, Fardin Fathi, Saman Bahrami
CA125, is a marker in the clinical diagnosis of several cancers and currently is the best serum-based tumor marker for ovarian cancer. Here, we developed an ultrasensitive antibody-ssDNA aptamer sandwich-type fluorescence immunosensor for CA125 detection. Based on a novel signal amplification strategy the carbon dots (CDs) functionalized with aptamer (CD-aptamer) used as detection probe and PAMAM-Dendrimers/AuNPs was used for covalent attachment of CA125-antibody and completing the sandwich assay method. By measuring of fluorescence resonance energy transfer (FRET) signals between CDs and AuNPs as nanoquenchers, the fluorescence signal quenched during sandwich complex formed between anti-CA125, CA125 and CDs-Aptamer and decreasing of fluorescence response signal is related to CA125 concentrations...
May 4, 2017: Biosensors & Bioelectronics
https://www.readbyqxmd.com/read/28522327/measurement-of-bacterial-capture-and-phagosome-maturation-of-kupffer-cells-by-intravital-microscopy
#3
Bas G J Surewaard, Paul Kubes
It is central to the field of bacterial pathogenesis to define how bacteria are killed by phagocytic cells. During phagocytosis, the microbe is localized to the phagolysosome where crucial defense mechanisms such as acidification and production of reactive oxygen species (ROS) are initiated. This process has extensively been studied in vitro, however many resident tissue phagocytes will phenotypically change upon isolation from their natural environment. Therefore, interrogation of phagocytosis and phagosomal function of cells in the context of their natural tissue environment enhances our understanding of the biological process in vivo...
May 15, 2017: Methods: a Companion to Methods in Enzymology
https://www.readbyqxmd.com/read/28514494/covalent-protein-labeling-by-spytag-spycatcher-in-fixed-cells-for-super-resolution-microscopy
#4
Veronica Pessino, Yemima Rose Citron, Siyu Feng, Bo Huang
Labeling proteins with high specificity and efficiency is a fundamental prerequisite for microscopic visualization of subcellular protein structures and interactions. While the comparatively small size of epitope tags makes them less perturbative to fusion proteins, they require the use of large antibodies that often limit probe accessibility and effective resolution. Here we use the covalent SpyTag-SpyCatcher system as an epitope-like tag for fluorescent labeling of intracellular proteins in fixed cells for both conventional and super-resolution microscopy...
May 17, 2017: Chembiochem: a European Journal of Chemical Biology
https://www.readbyqxmd.com/read/28508361/photoaffinity-labeling-of-pentameric-ligand-gated-ion-channels-a-proteomic-approach-to-identify-allosteric-modulator-binding-sites
#5
Selwyn S Jayakar, Gordon Ang, David C Chiara, Ayman K Hamouda
Photoaffinity labeling techniques have been used for decades to identify drug binding sites and to study the structural biology of allosteric transitions in transmembrane proteins including pentameric ligand-gated ion channels (pLGIC). In a typical photoaffinity labeling experiment, to identify drug binding sites, UV light is used to introduce a covalent bond between a photoreactive ligand (which upon irradiation at the appropriate wavelength converts to a reactive intermediate) and amino acid residues that lie within its binding site...
2017: Methods in Molecular Biology
https://www.readbyqxmd.com/read/28507297/a-one-pot-three-component-double-click-method-for-synthesis-of-67-cu-labeled-biomolecular-radiotherapeutics
#6
Katsumasa Fujiki, Shinya Yano, Takeshi Ito, Yuki Kumagai, Yoshinori Murakami, Osamu Kamigaito, Hiromitsu Haba, Katsunori Tanaka
A one-pot three-component double-click process for preparing tumor-targeting agents for cancer radiotherapy is described here. By utilizing DOTA (or NOTA) containing tetrazines and the TCO-substituted aldehyde, the two click reactions, the tetrazine ligation (an inverse electron-demand Diels-Alder cycloaddition) and the RIKEN click (a rapid 6π-azaelectrocyclization), could simultaneously proceed under mild conditions to afford covalent attachment of the metal chelator DOTA or NOTA to biomolecules such as to albumin and anti-IGSF4 antibody without altering their activities...
May 15, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28504684/fully-automated-5-plex-fluorescent-immunohistochemistry-with-tyramide-signal-amplification-and-same-species-antibodies
#7
Wenjun Zhang, Antony Hubbard, Tobin Jones, Adriana Racolta, Srabani Bhaumik, Nick Cummins, Liping Zhang, Karl Garsha, Frank Ventura, Mark R Lefever, Zhenqiang Lu, John K Hurley, William A Day, Lidija Pestic-Dragovich, Larry E Morrison, Lei Tang
The ability to simultaneously visualize the presence, abundance, location and functional state of many targets in cells and tissues has been described as a true next-generation approach in immunohistochemistry (IHC). A typical requirement for multiplex IHC (mIHC) is the use of different animal species for each primary (1°Ab) and secondary (2°Ab) antibody pair. Although 1°Abs from different species have been used with differently labeled species-specific 2°Abs, quite often the appropriate combination of antibodies is not available...
May 15, 2017: Laboratory Investigation; a Journal of Technical Methods and Pathology
https://www.readbyqxmd.com/read/28501859/molecular-insights-into-covalently-stained-carious-dentine-using-solid-state-nmr-and-tof-sims
#8
Ulrica S Almhöjd, Peter Lingström, Åke Nilsson, Jörgen G Norén, Sandra Siljeström, Åsa Östlund, Diana Bernin
Dyes currently used to stain carious dentine have a limited capacity to discriminate normal dentine from carious dentine, which may result in overexcavation. Consequently, finding a selective dye is still a challenge. However, there is evidence that hydrazine-based dyes, via covalent bonds to functional groups, bind specifically to carious dentine. The aim of this study was to investigate the possible formation of covalent bonds between carious dentine and 15N2-hydrazine and the hydrazine-based dye, 15N2-labelled Lucifer Yellow, respectively...
May 13, 2017: Caries Research
https://www.readbyqxmd.com/read/28485577/site-selective-conjugation-of-native-proteins-with-dna
#9
Julie B Trads, Thomas Tørring, Kurt V Gothelf
Conjugation of DNA to proteins is increasingly used in academia and industry to provide proteins with tags for identification or handles for hybridization to other DNA strands. Assay technologies such as immuno-PCR and proximity ligation and the imaging technology DNA-PAINT require DNA-protein conjugates. In DNA nanotechnology, the DNA handle is exploited to precisely position proteins by self-assembly. For these applications, site-selective conjugation is almost always desired because fully functional proteins are required to maintain the specificity of antibodies and the activity of enzymes...
May 9, 2017: Accounts of Chemical Research
https://www.readbyqxmd.com/read/28473247/oxidized-5-aminosalicylic-acid-activates-nrf2-ho-1-pathway-by-covalently-binding-to-keap1-implication-in-anti-inflammatory-actions-of-5-aminosalicylic-acid
#10
Sookjin Kang, Wooseong Kim, Seongkeun Jeong, Yonghyun Lee, Joon Nam, Sunyoung Lee, Yunjin Jung
Mesalazine (5-aminosalicylic acid, 5-ASA), a currently used drug for anti-inflammatory bowel disease, is easily oxidized by HOCl, a strong oxidant generated in gut inflammation, to produce electrophilic quinones. We investigated whether this chemical feature has an implication in the anti-inflammatory pharmacology of 5-ASA. Human colon carcinoma HCT116 cells were treated with HOCl-reacted 5-ASA. Oxidized 5-ASA activated Nrf2 while 5-ASA itself was not effective. Activation of Nrf2 led to induction of hemeoxygenase (OH)-1, an anti-inflammatory enzyme...
May 1, 2017: Free Radical Biology & Medicine
https://www.readbyqxmd.com/read/28470883/selective-covalent-protein-modification-by-4-halopyridines-through-catalysis
#11
Christopher Schardon, Alfred Tuley, Joyce Er, Jake Swartzel, Walter Fast
4-Halopyridines are developed herein as selective, tunable, and "switchable" covalent protein modifiers for use in the development of chemical probes. Non-enzymatic reactivity of 4-chloropyridine with amino acids and thiols is ranked with respect to common covalent protein modifying reagents and found to have reactivity similar to that of acrylamide, but can be switched to a reactivity similar to that of iodoacetamide upon stabilization of the positively charged pyridinium. Diverse fragment-sized 4-halopyridines inactivate human dimethylarginine dimethylaminohydrolase-1 (DDAH1) through covalent modification of the active-site Cys, acting as quiescent affinity labels that require "off pathway" catalysis via a stabilization of the protonated pyridinium by a neighboring Asp residue...
May 3, 2017: Chembiochem: a European Journal of Chemical Biology
https://www.readbyqxmd.com/read/28467613/charged-macromolecular-rhenium-bipyridine-catalysts-with-tunable-co2-reduction-potentials
#12
Nathan Claude Gianneschi, Swagat Sahu, Po Ling Cheung, Charles Machan, Steven Chabolla, Clifford Kubiak
A series of polymeric frameworks with functional assemblies were designed to alter the catalytic activity of covalently bound Re(I) electrocatalysts. Norbornenyl polymers containing positively charged quaternary ammonium salts, neutral phenyl, or negatively charged trifluoroborate groups were end-labelled with a Re(I) fac-tricarbonyl bipyridine electrocatalyst via cross metathesis. Electrochemical studies in acetonitrile under an inert atmosphere and with saturated CO2, indicate that the quaternary ammonium polymers exhibit a significantly lower potential for CO2 reduction to CO (ca...
May 3, 2017: Chemistry: a European Journal
https://www.readbyqxmd.com/read/28451235/welcoming-natural-isotopic-abundance-in-solid-state-nmr-probing-%C3%AF-stacking-and-supramolecular-structure-of-organic-nanoassemblies-using-dnp
#13
Katharina Märker, Subhradip Paul, Carlos Fernández-de-Alba, Daniel Lee, Jean-Marie Mouesca, Sabine Hediger, Gaël De Paëpe
The self-assembly of small organic molecules is an intriguing phenomenon, which provides nanoscale structures for applications in numerous fields from medicine to molecular electronics. Detailed knowledge of their structure, in particular on the supramolecular level, is a prerequisite for the rational design of improved self-assembled systems. In this work, we prove the feasibility of a novel concept of NMR-based 3D structure determination of such assemblies in the solid state. The key point of this concept is the deliberate use of samples that contain (13)C at its natural isotopic abundance (NA, 1...
February 1, 2017: Chemical Science
https://www.readbyqxmd.com/read/28447750/biological-effects-of-bone-marrow-mesenchymal-stem-cells-on-hepatitis-b-virus-in%C3%A2-vitro
#14
Wei-Ping Zheng, Bo-Ya Zhang, Zhong-Yang Shen, Ming-Li Yin, Yi Cao, Hong-Li Song
The aim of the present study was to explore the effects of co‑culturing bone marrow‑derived mesenchymal stem cells (BM-MSCs) cultured with hepatitis B virus (HBV)‑infected lymphocytes in vitro. BM‑MSCs and lymphocytes from Brown Norway rats were obtained from the bone marrow and spleen, respectively. Rats were divided into the following five experimental groups: Group 1, splenic lymphocytes (SLCs); group 2, HepG2.2.15 cells; group 3, BM‑MSCs + HepG2.2.15 cells; group 4, SLCs + HepG2.2.15 cells; and group 5, SLCs + BM‑MSCs + HepG2...
May 2017: Molecular Medicine Reports
https://www.readbyqxmd.com/read/28445813/microfluidic-integrated-patterned-ito-immunosensor-for-rapid-detection-of-prostate-specific-membrane-antigen-biomarker-in-prostate-cancer
#15
Rajesh Seenivasan, Chandra K Singh, Jay W Warrick, Nihal Ahmad, Sundaram Gunasekaran
An optically transparent patterned indium tin oxide (ITO) three-electrode sensor integrated with a microfluidic channel was designed for label-free immunosensing of prostate-specific membrane antigen (PSMA), a prostate cancer (PCa) biomarker, expressed on prostate tissue and circulating tumor cells but also found in serum. The sensor relies on cysteamine capped gold nanoparticles (N-AuNPs) covalently linked with anti-PSMA antibody (Ab) for target specificity. A polydimethylsiloxane (PDMS) microfluidic channel is used to efficiently and reproducibly introduce sample containing soluble proteins/cells to the sensor...
September 15, 2017: Biosensors & Bioelectronics
https://www.readbyqxmd.com/read/28434875/covalent-protein-labeling-at-glutamic-acids
#16
Pablo Martín-Gago, Eyad K Fansa, Michael Winzker, Sandip Murarka, Petra Janning, Carsten Schultz-Fademrecht, Matthias Baumann, Alfred Wittinghofer, Herbert Waldmann
Covalent labeling of amino acids in proteins by reactive small molecules, in particular at cysteine SH and lysine NH groups, is a powerful approach to identify and characterize proteins and their functions. However, for the less-reactive carboxylic acids present in Asp and Glu, hardly any methodology is available. Employing the lipoprotein binding chaperone PDE6δ as an example, we demonstrate that incorporation of isoxazolium salts that resemble the structure and reactivity of Woodward's reagent K into protein ligands provides a novel method for selective covalent targeting of binding site carboxylic acids in whole proteomes...
May 18, 2017: Cell Chemical Biology
https://www.readbyqxmd.com/read/28430191/activating-lattice-oxygen-redox-reactions-in-metal-oxides-to-catalyse-oxygen-evolution
#17
Alexis Grimaud, Oscar Diaz-Morales, Binghong Han, Wesley T Hong, Yueh-Lin Lee, Livia Giordano, Kelsey A Stoerzinger, Marc T M Koper, Yang Shao-Horn
Understanding how materials that catalyse the oxygen evolution reaction (OER) function is essential for the development of efficient energy-storage technologies. The traditional understanding of the OER mechanism on metal oxides involves four concerted proton-electron transfer steps on metal-ion centres at their surface and product oxygen molecules derived from water. Here, using in situ (18)O isotope labelling mass spectrometry, we provide direct experimental evidence that the O2 generated during the OER on some highly active oxides can come from lattice oxygen...
May 2017: Nature Chemistry
https://www.readbyqxmd.com/read/28429595/ultrasensitive-detection-of-micrornas-with-morpholino-functionalized-nanochannel-biosensor
#18
Tangbin Liao, Xiaorui Li, Qian Tong, Kai Zou, Hang Zhang, Lina Tang, Zhongyue Sun, Guo-Jun Zhang
Here, we demonstrate a phosphorodiamidate morpholino oligos (PMO)-functionalized nanochannel biosensor for label-free detection of microRNAs (miRNAs) with ultrasensitivity and high sequence specificity. PMO, as a capture probe, was covalently anchored on the nanochannel surface. Because of the neutral character and high sequence-specific affinity of PMO, hybridization efficiency between PMO and miRNAs was enhanced, thus largely decreasing background signals and highly improving the detection specificity and sensitivity...
April 28, 2017: Analytical Chemistry
https://www.readbyqxmd.com/read/28420127/glycosaminoglycan-binding-and-non-endocytic-membrane-translocation-of-cell-permeable-octaarginine-monitored-by-real-time-in-cell-nmr-spectroscopy
#19
Yuki Takechi-Haraya, Kenzo Aki, Yumi Tohyama, Yuichi Harano, Toru Kawakami, Hiroyuki Saito, Emiko Okamura
Glycosaminoglycans (GAGs), which are covalently-linked membrane proteins at the cell surface have recently been suggested to involve in not only endocytic cellular uptake but also non-endocytic direct cell membrane translocation of arginine-rich cell-penetrating peptides (CPPs). However, in-situ comprehensive observation and the quantitative analysis of the direct membrane translocation processes are challenging, and the mechanism therefore remains still unresolved. In this work, real-time in-cell NMR spectroscopy was applied to investigate the direct membrane translocation of octaarginine (R8) into living cells...
April 15, 2017: Pharmaceuticals
https://www.readbyqxmd.com/read/28417900/green-approach-to-photoluminescent-carbon-dots-for-imaging-of-gram-negative-bacteria-escherichia-coli
#20
Poushali Das, Madhuparna Bose, Sayan Ganguly, Subhadip Mondal, Amit Kumar Das, Susanta Banerjee, Narayan Chandra Das
Fluorescent carbon dots, zero-dimensional nanomaterials with surface ligands, have been studied extensively over the past few years in biolabelling or fluorescence-based live cell assays. In the past, synthetic organic dyes have been used as cell tracking materials, but they have severe limitations; fluorescent carbon dots may pave the way to biolabelling and cell imaging. In this work, green fluorescent carbon dots have been synthesized from a green source, gram, without any sort of covalent or ionic modifications...
May 12, 2017: Nanotechnology
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