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https://www.readbyqxmd.com/read/29774924/fluorescence-resonance-energy-transfer-fret-based-nanoparticles-composed-of-aie-luminogens-and-nir-dyes-with-enhanced-three-photon-near-infrared-emission-for-in-vivo-brain-angiography
#1
Wen Liu, Yalun Wang, Xiao Han, Ping Lu, Liang Zhu, Chaowei Sun, Jun Qian, Sailing He
Near-infrared (NIR) fluorescence is very important for high-contrast biological imaging of high-scattering tissues such as brain tissue. Unfortunately, commercial NIR dyes are excited usually by visible light, and their multi-photon absorption (MPA) cross-sections are small. Here, we design new co-encapsulated NIR nanoparticles (NPs) with a large three-photon (3PA) absorption cross-section. A form of aggregation-induced emission (AIE) luminogen (AIEgen), 2,3-bis(4'-(diphenylamino)-[1,1'-biphenyl]-4-yl) fumaronitrile (TPATCN), is introduced as the donor, and a form of NIR dye, silicon 2,3-naphthalocyanine bis-(trihexylsilyloxide) (NIR775), is adopted as the acceptor...
May 18, 2018: Nanoscale
https://www.readbyqxmd.com/read/29774421/a-fluorometric-aptasensor-for-methamphetamine-based-on-fluorescence-resonance-energy-transfer-using-cobalt-oxyhydroxide-nanosheets-and-carbon-dots
#2
Zeinab Saberi, Behzad Rezaei, Hossein Faroukhpour, Ali Ashghar Ensafi
Cobalt oxyhydroxide (CoOOH) nanosheets are efficient fluorescence quenchers due to their specific optical properties and high surface area. The combination of CoOOH nanosheets and carbon dots (CDs) has not been used in any aptasensor based on fluorescence quenching so far. An aptamer based fluorometric assay is introduced that is making use of fluorescent CDs conjugated to the aptamer against methamphetamine (MTA), and of CoOOH nanosheets which reduce the fluorescence of the CDs as a quencher. The results revealed that the conjugated CDs with aptamers were able to enclose the CoOOH nanosheets...
May 17, 2018: Mikrochimica Acta
https://www.readbyqxmd.com/read/29771640/phosphorylation-of-snap-23-at-ser95-causes-a-structural-alteration-and-negatively-regulates-fc-receptor-mediated-phagosome-formation-and-maturation-in-macrophages
#3
Chiye Sakurai, Makoto Itakura, Daiki Kinoshita, Seisuke Arai, Hitoshi Hashimoto, Ikuo Wada, Kiyotaka Hatsuzawa
SNAP-23 is a plasma membrane-localized SNARE protein involved in Fc receptor (FcR)-mediated phagocytosis. However, the regulatory mechanism underlying its function remains elusive. Using phosphorylation specific-antibodies, SNAP-23 was found to be phosphorylated at Ser95 in macrophages. To understand the role of this phosphorylation, we established macrophage lines overexpressing the non-phosphorylatable S95A or the phospho-mimicking S95D mutation. The efficiency of phagosome formation and maturation was severely reduced in SNAP-23-S95D-overexpressing cells...
May 17, 2018: Molecular Biology of the Cell
https://www.readbyqxmd.com/read/29770128/critical-functions-of-region-1-67-and-helix-xiii-in-retaining-the-active-structure-of-nhad-antiporter-in-halomonas-sp-y2
#4
Zhou Yang, Yiwei Meng, Qi Zhao, Bin Cheng, Ping Xu, Chunyu Yang
NhaD-type antiporters are mainly distributed in various Proteobacteria , especially in marine microorganisms and human pathogens. This distribution as well as the pathogenic properties of these strains suggest that these antiporters contribute to the regulation of high osmoregulation and are potential drug targets. Two NhaD homologs, NhaD1 and NhaD2, from the halotolerant and alkaliphilic Halomonas sp. Y2 exhibits similar, high in vitro activity, but remarkably different in vivo functions. To search for critical domains or residues involved in these differences of physiological functions, various chimeras composed of NhaD1 and NhaD2 segments were generated...
2018: Frontiers in Microbiology
https://www.readbyqxmd.com/read/29769636/molecular-details-of-dimerization-kinetics-reveal-negligible-populations-of-transient-%C3%A2%C2%B5-opioid-receptor-homodimers-at-physiological-concentrations
#5
Derya Meral, Davide Provasi, Diego Prada-Gracia, Jan Möller, Kristen Marino, Martin J Lohse, Marta Filizola
Various experimental and computational techniques have been employed over the past decade to provide structural and thermodynamic insights into G Protein-Coupled Receptor (GPCR) dimerization. Here, we use multiple microsecond-long, coarse-grained, biased and unbiased molecular dynamics simulations (a total of ~4 milliseconds) combined with multi-ensemble Markov state models to elucidate the kinetics of homodimerization of a prototypic GPCR, the µ-opioid receptor (MOR), embedded in a 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC)/cholesterol lipid bilayer...
May 16, 2018: Scientific Reports
https://www.readbyqxmd.com/read/29768679/aza-macrocyclic-triphenylamine-ligands-for-g-quadruplex-recognition
#6
Enrique Victor García-España, Isabel Pont, Jorge González-García, Mario Inclán, Matthew Reynolds, Estefanía Delgado-Pinar, M Teresa Albelda, Ramon Vilar
A new series of triphenylamine-based ligands with one (TPA1PY), two (TPA2PY) or three pending aza-macrocycle(s) (TPA3PY) have been synthesised and studied by means of pH-metric titrations, UV/Vis spectroscopy and fluorescence experiments. The affinity of these ligands for G-quadruplex (G4) DNA and its selectivity over duplex DNA were investigated by FRET melting assays, fluorimetric titrations and circular dichroism (CD) spectroscopy. Interestingly, the interaction of the bi- and specially the tri-branched ligand with G4 leads to a very intense red-shifted fluorescence emission band which may be associated with intermolecular aggregation between the molecule and the DNA...
May 16, 2018: Chemistry: a European Journal
https://www.readbyqxmd.com/read/29767997/dissecting-conformational-dynamics-modulated-enzyme-catalysis-with-single-molecule-fret
#7
Shaowen Wu, Jianwei Liu, Wenning Wang
Conformational changes of enzyme proteins are often coupled with the catalytic reaction and modulate the enzyme activity. Single molecule technology is a powerful tool to study the mechanism of enzyme catalysis in these complicated cases. However, the chemical reaction cycles and conformational changes could not be monitored simultaneously in a single molecule detection experiment, resulting in some key kinetic parameters unresolved. Here, we describe a method to extract all kinetic parameters from comprehensive single molecule FRET (smFRET) measurements and model analysis...
May 16, 2018: Journal of Physical Chemistry. B
https://www.readbyqxmd.com/read/29767969/single-molecule-imaging-reveals-conformational-manipulation-of-holliday-junction-dna-by-the-junction-processing-protein-ruva
#8
Dalton Gibbs, Soma Dhakal
Interactions between DNA and motor proteins regulate nearly all biological functions of DNA such as gene expression, DNA replication and repair, and transcription. During the late stages of homologous recombination (HR), the Escherichia coli recombination machinery, RuvABC, resolves the four-way DNA motifs called Holliday junctions (HJs) that are formed during exchange of nucleotide sequences between two homologous duplex DNA. Although the formation of RuvA-HJ complex is known to be the first critical step in the RuvABC pathway, the mechanism for the binding interaction between RuvA and HJ has remained elusive...
May 16, 2018: Biochemistry
https://www.readbyqxmd.com/read/29767755/protein-phosphatase-2c-ap2c1-interacts-with-and-negatively-regulates-the-function-of-cipk9-under-potassium-deficient-conditions-in-arabidopsis
#9
Amarjeet Singh, Akhilesh K Yadav, Kanwaljeet Kaur, Sibaji K Sanyal, Saroj K Jha, Joel L Fernandes, Pankhuri Sharma, Indu Tokas, Amita Pandey, Sheng Luan, Girdhar K Pandey
Potassium (K+) is a major macronutrient required for plant growth. In response to low- K+ condition, an adaptive mechanism entails activation of the Ca2+ signaling network consisting of calcineurin B-like proteins (CBLs) and their interacting kinases (CIPKs) in plants. The CBL-interacting protein kinase 9 (CIPK9) is previously implicated in low-K+ responses in Arabidopsis thaliana. Here, we report a protein phosphatase 2C (PP2C), AP2C1, as an interactor of CIPK9. Fluorescence resonance energy transfer (FRET), bimolecular fluorescence complementation (BiFC) and co-localization analyses revealed that CIPK9 and AP2C1 interact in the cytoplasm...
May 15, 2018: Journal of Experimental Botany
https://www.readbyqxmd.com/read/29766713/probing-dna-hybridization-equilibrium-by-cationic-conjugated-polymer-for-highly-selective-detection-and-imaging-of-single-nucleotide-mutation
#10
Zehao Li, Xu Zhou, Lidan Li, Shue Liu, Congshan Wang, Lina Li, Changyuan Yu, Xin Su
Hybridization-based probes emerge as a promising tool for nucleic acid target detection and imaging. However, the single-nucleotide selectivity is still challenging because the specificity of hybridization reaction is typically low at room temperature. We disclose an effective and simple method for highly selective detection and in situ imaging of single-nucleotide mutation (SNM) by taking the advantages of the specific hybridization of short duplex and the signal amplifying effect of cationic conjugated polymer (CCP)...
May 16, 2018: Analytical Chemistry
https://www.readbyqxmd.com/read/29764938/redistribution-of-serca-calcium-pump-conformers-during-intracellular-calcium-signaling
#11
Olga N Raguimova, Nikolai Smolin, Elisa Bovo, Siddharth Bhayani, Joseph M Autry, Aleksey V Zima, Seth L Robia
The conformational changes of a calcium transport A TPase were investigated with molecular dynamics (MD) simulations as well as fluorescence resonance energy transfer (FRET) measurements to determine the significance of a discrete structural element for regulation of the conformational dynamics of the transport cycle. Previous MD simulations indicated that a loop in the cytosolic domain of the SERCA calcium transporter facilitates an open-to-closed structural transition. To investigate the significance of this structural element, we performed additional MD simulations and new biophysical measurements of SERCA structure and function...
May 15, 2018: Journal of Biological Chemistry
https://www.readbyqxmd.com/read/29764756/straightforward-hit-identification-approach-in-fragment-based-discovery-of-bromodomain-containing-protein-4-brd4-inhibitors
#12
Petro Borysko, Yurii S Moroz, Oleksandr V Vasylchenko, Vasyl V Hurmach, Anastasia Starodubtseva, Natalia Stefanishena, Kateryna Nesteruk, Sergey Zozulya, Ivan S Kondratov, Oleksandr O Grygorenko
A combination approach of a fragment screening and "SAR by catalog" was used for the discovery of bromodomain-containing protein 4 (BRD4) inhibitors. Initial screening of 3695-fragment library against bromodomain 1 of BRD4 using thermal shift assay (TSA), followed by initial hit validation, resulted in 73 fragment hits, which were used to construct a follow-up library selected from available screening collection. Additionally, analogs of inactive fragments, as well as a set of randomly selected compounds were also prepared (3 × 3200 compounds in total)...
May 9, 2018: Bioorganic & Medicinal Chemistry
https://www.readbyqxmd.com/read/29763760/multispectroscopic-and-bioimaging-approach-for-the-interaction-of-rhodamine-6g-capped-gold-nanoparticles-with-bovine-serum-albumin
#13
N Manjubaashini, Mookkandi Palsamy Kesavan, Jegathalaprathaban Rajesh, T Daniel Thangadurai
Binding interaction of Bovine Serum Albumin (BSA) with newly prepared rhodamine 6G-capped gold nanoparticles (Rh6G-Au NPs) under physiological conditions (pH 7.2) was investigated by a wide range of photophysical techniques. Rh6G-Au NPs caused the static quenching of the intrinsic fluorescence of BSA that resulted from the formation of ground-state complex between BSA and Rh6G-Au NPs. The binding constant from fluorescence quenching method (Ka  = 1.04 × 104  L mol-1 ; LoD = 14.0 μM) is in accordance with apparent association constant (Kapp  = 1...
May 7, 2018: Journal of Photochemistry and Photobiology. B, Biology
https://www.readbyqxmd.com/read/29763544/multi-fluorophore-dna-origami-beacon-as-a-biosensing-platform
#14
Denis Selnihhin, Steffen Møller Sparvath, Søren Preus, Victoria Birkedal, Ebbe Sloth Andersen
Biosensors play increasingly important roles in many fields, from clinical diagnosis to environmental monitoring, and there is a growing need for cheap and simple analytical devices. DNA nanotechnology provides methods for the creation of sophisticated biosensors, however many of the developed DNA-based sensors are limited by cumbersome and time-consuming readouts involving advanced experimental techniques. Here we describe design, construction and characterization of an optical DNA origami nano-biosensor device exploiting arrays of precisely positioned organic fluorophores...
May 15, 2018: ACS Nano
https://www.readbyqxmd.com/read/29763513/child-onset-thrombotic-thrombocytopenic-purpura-caused-by-p-r498c-and-p-g259pfsx133-mutations-in-adamts13
#15
An-Sofie Schelpe, Christelle Orlando, Bogaç Ercig, Chloë Geeroms, Inge Pareyn, Nele Vandeputte, Leydi Carolina Velásquez Pereira, Elien Roose, Karel Fostier, Gerry A F Nicolaes, Hans Deckmyn, Simon F De Meyer, Karen Vanhoorelbeke, Kristin Jochmans
INTRODUCTION: Patients suffering from congenital thrombotic thrombocytopenic purpura (cTTP) have a deficiency in ADAMTS13 due to mutations in their ADAMTS13 gene. OBJECTIVE: The aim of this study was to determine ADAMTS13 parameters (activity, antigen and mutations), to investigate if the propositus suffered from child-onset cTTP and to study the in vitro effect of the ADAMTS13 mutations. METHODS: ADAMTS13 activity and antigen were determined using the FRETS VWF73 assay and ELISA and ADAMTS13 mutations via sequencing of the exons...
May 15, 2018: European Journal of Haematology
https://www.readbyqxmd.com/read/29762718/cell-penetrating-thiazole-peptides-inhibit-c-myc-expression-via-site-specific-targeting-of-c-myc-g-quadruplex
#16
Debasish Dutta, Manish Debnath, Diana Müller, Rakesh Paul, Tania Das, Irene Bessi, Harald Schwalbe, Jyotirmayee Dash
The structural differences among different G-quadruplexes provide an opportunity for site-specific targeting of a particular G-quadruplex structure. However, majority of G-quadruplex ligands described thus far show little selectivity among different G-quadruplexes. In this work, we delineate the design and synthesis of a crescent-shaped thiazole peptide that preferentially stabilizes c-MYC quadruplex over other promoter G-quadruplexes and inhibits c-MYC oncogene expression. Biophysical analysis such as Förster resonance energy transfer (FRET) melting and fluorescence spectroscopy show that the thiazole peptide TH3 can selectively interact with the c-MYC G-quadruplex over other investigated G-quadruplexes and duplex DNA...
May 14, 2018: Nucleic Acids Research
https://www.readbyqxmd.com/read/29762682/molecular-detection-of-mutations-involved-in-helicobacter-pylori-antibiotic-resistance-in-algeria
#17
Meryem Bachir, Rachida Allem, Lucie Benejat, Abedelkarim Tifrit, Meriem Medjekane, Amine El-Mokhtar Drici, Francis Megraud, Kara Turki Douidi
Objectives: In Algeria, there are limited data regarding the pattern of Helicobacter pylori primary antibiotic resistance. The aim of this study was to evaluate the primary resistance of H. pylori to clarithromycin, ciprofloxacin, tetracycline and rifampicin and to determine the molecular mechanisms involved in the resistance. Methods: Two hundred and seventy Algerian adults who had never received H. pylori treatment were enrolled in this study. Human biopsies were obtained for culture and antimicrobial susceptibility testing was performed by Etest for clarithromycin, ciprofloxacin, tetracycline and rifampicin...
May 11, 2018: Journal of Antimicrobial Chemotherapy
https://www.readbyqxmd.com/read/29760772/engineering-a-palette-of-eukaryotic-chromoproteins-for-bacterial-synthetic-biology
#18
Josefine Liljeruhm, Saskia K Funk, Sandra Tietscher, Anders D Edlund, Sabri Jamal, Pikkei Wistrand-Yuen, Karl Dyrhage, Arvid Gynnå, Katarina Ivermark, Jessica Lövgren, Viktor Törnblom, Anders Virtanen, Erik R Lundin, Erik Wistrand-Yuen, Anthony C Forster
Background: Coral reefs are colored by eukaryotic chromoproteins (CPs) that are homologous to green fluorescent protein. CPs differ from fluorescent proteins (FPs) by intensely absorbing visible light to give strong colors in ambient light. This endows CPs with certain advantages over FPs, such as instrument-free detection uncomplicated by ultra-violet light damage or background fluorescence, efficient Förster resonance energy transfer (FRET) quenching, and photoacoustic imaging. Thus, CPs have found utility as genetic markers and in teaching, and are attractive for potential cell biosensor applications in the field...
2018: Journal of Biological Engineering
https://www.readbyqxmd.com/read/29759177/highly-sensitive-detection-of-hepatitis-c-virus-dna-by-using-a-one-donor-four-acceptors-fret-probe
#19
Ping Zeng, Peng Hou, Chun Ju Jing, Cheng Zhi Huang
Sensitive detection of Hepatitis C virus (HCV) DNA is critical to treat and prevent the propagation of hepatitis C diseases. Herein a FRET probe of One-Donor-Multi-Acceptors (D-mA) assembly is designed through the formation of triple-helix DNA structure, which can greatly reduce the background of FRET system so as to greatly increase the detection sensitivity of hepatitis C virus DNA with the limit of detection (3σ) being 24.57 nmol/L, making the detection of clinic samples successful and showing that the newly developed FRET probe of D-mA assembly could be applied for the early diagnosis and treatment of hepatitis C disease...
August 1, 2018: Talanta
https://www.readbyqxmd.com/read/29751735/identification-of-compounds-that-prolong-type-i-interferon-signaling-as-potential-vaccine-adjuvants
#20
Nikunj M Shukla, Kei-Ichiro Arimoto, Shiyin Yao, Jun-Bao Fan, Yue Zhang, Fumi Sato-Kaneko, Fitzgerald S Lao, Tadashi Hosoya, Karen Messer, Minya Pu, Howard B Cottam, Dennis A Carson, Tomoko Hayashi, Dong-Er Zhang, Maripat Corr
Vaccines are reliant on adjuvants to enhance the immune stimulus, and type I interferons (IFNs) have been shown to be beneficial in augmenting this response. We were interested in identifying compounds that would sustain activation of an endogenous type I IFN response as a co-adjuvant. We began with generation of a human monocytic THP-1 cell line with an IFN-stimulated response element (ISRE)-β-lactamase reporter construct for high-throughput screening. Pilot studies were performed to optimize the parameters and conditions for this cell-based Förster resonance energy transfer (FRET) reporter assay for sustaining an IFN-α-induced ISRE activation signal...
May 1, 2018: SLAS Discovery
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