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https://www.readbyqxmd.com/read/28088110/highly-sensitive-detection-of-cysteine-over-glutathione-and-homo-cysteine-new-insight-into-the-michael-addition-of-mercapto-group-to-maleimide
#1
Zhaoyang Chen, Qian Sun, Yuhua Yao, Xiaoxiang Fan, Weibing Zhang, Junhong Qian
A fluorescence "off-on" probe CMP for thiols was designed with coumarin as the fluorophore and maleimide as the receptor. The fluorescence of the coumarin was quenched through photoinduced electron transfer (PET) from the fluorophore to maleimide group. The Michael addition of the mercapto group toward maleimide formed a thioether with relatively weak fluorescence. The intramolecular nucleophilic substitution of amino group in cysteine (Cys) to alkylthio produced a much stronger fluorescent amino adduct, which was supported by UPLC-MS and NMR titration...
January 7, 2017: Biosensors & Bioelectronics
https://www.readbyqxmd.com/read/28081500/a-highly-sensitive-quantum-dots-dna-nanobiosensor-based-on-fluorescence-resonance-energy-transfer-for-rapid-detection-of-nanomolar-amounts-of-human-papillomavirus-18
#2
Mojtaba Shamsipur, Vahid Nasirian, Kamran Mansouri, Ali Barati, Asad Veisi-Raygani, Soheila Kashanian
A very sensitive and convenient nanobiosensor based on fluorescence resonance energy transfer (FRET) was developed for the detection of a 22-mer oligonucleotides sequence in Human Papillomavirus 18 virus (HPV18) gene. For this purpose, water-soluble CdTe quantum dots (QDs) were synthesized and, subsequently, amino-modified 11-mer oligonucleotide as one of the two necessary probes was attached to QDs surface to form functional QDs-DNA conjugates. Right after addition of the QDs-DNA and a second Cyanine5 (Cy5)-labeled 11-mer oligonucleotide probe to the DNA target solution, the sandwiched hybrids were formed...
January 3, 2017: Journal of Pharmaceutical and Biomedical Analysis
https://www.readbyqxmd.com/read/28079054/local-dimensionality-determines-imaging-speed-in-localization-microscopy
#3
Patrick Fox-Roberts, Richard Marsh, Karin Pfisterer, Asier Jayo, Maddy Parsons, Susan Cox
Localization microscopy allows biological samples to be imaged at a length scale of tens of nanometres. Live-cell super-resolution imaging is rare, as it is generally assumed to be too slow for dynamic samples. The speed of data acquisition can be optimized by tuning the density of activated fluorophores in each time frame. Here, we show that the maximum achievable imaging speed for a particular structure varies by orders of magnitude, depending on the sample dimensionality (that is, whether the sample is more like a point, a strand or an extended structure such as a focal adhesion)...
January 12, 2017: Nature Communications
https://www.readbyqxmd.com/read/28078632/fluorescent-carbon-dot-as-nanosensor-for-sensitive-and-selective-detection-of-cefixime-based-on-inner-filter-effect
#4
Farhad Akhgari, Naser Samadi, Khalil Farhadi
Here a simple and sensitive fluorescent assay for detecting Cefixime based on inner filter effect (IFE) has been proven, which is conceptually different from the previously reported CEF fluorescent assays. In this sensing platform, fluorescent carbon dots (CDs) were prepared by one-pot synthesis and was directly used as fluorophore in IFE. The method is based on the complexation reaction between cefixime and palladium ion in the presence of acidic buffer solution (pH 4). The Pd(II)-CEFcomplex was capable of functioning as a powerful absorber in IFE to influence the excitation of fluorophore (CDs)...
January 11, 2017: Journal of Fluorescence
https://www.readbyqxmd.com/read/28077373/determination-of-renal-function-and-injury-using-near-infrared-fluorimetry-in-experimental-cardiorenal-syndrome
#5
Mizuko Ikeda, Rumie Wakasaki, Katie J Schenning, Thomas Swide, Jeong Heon Lee, M Bernie Miller, Hak Soo Choi, Sharon Anderson, Michael P Hutchens
Cardiorenal syndrome type 1 causes acute kidney injury but is poorly understood; animal models and diagnostic aids are lacking. Robust noninvasive measurements of glomerular filtration rate are required for injury models and clinical use. Several have been described but are untested in translational models and suffer from biologic interference. We developed a mouse model of cardiorenal syndrome and tested the novel near-infrared fluorophore, ZW800-1, to assess renal and cardiac function. We performed murine cardiac arrest and cardiopulmonary resuscitation followed by transthoracic echocardiography, 2- and 24h later...
January 11, 2017: American Journal of Physiology. Renal Physiology
https://www.readbyqxmd.com/read/28077285/a-fluorophore-fusion-construct-of-human-profilin-i-with-non-compromized-poly-l-proline-binding-capacity-suitable-for-imaging
#6
Michaela Nejedla, Zhilun Li, Anna E Masser, Matteo Biancospino, Matthias Spiess, Sebastian D Mackowiak, Marc R Friedländer, Roger Karlsson
Profilin is vital for actin organization in eukaryotic cells. It controls actin filament formation by binding monomeric actin and numerous proteins involved in polarized actin assembly. Important for the latter is the interaction surface formed by the N- and C-terminal helices, which pack close to each other on one side of the molecule at distance from the actin site and mediate binding to poly-proline sequences present in many of the targeted proteins. Via these interactions profilin contributes to the spatiotemporal control of actin filament growth...
January 7, 2017: Journal of Molecular Biology
https://www.readbyqxmd.com/read/28075574/visualization-of-mycobacterial-membrane-dynamics-in-live-cells
#7
Frances P Rodriguez-Rivera, Xiaoxue Zhou, Julie A Theriot, Carolyn R Bertozzi
Mycobacteria are endowed with a highly impermeable mycomembrane that confers intrinsic resistance to many antibiotics. Several unique mycomembrane glycolipids have been isolated and structurally characterized, but the underlying organization and dynamics of glycolipids within the cell envelope remain poorly understood. We report here a study of mycomembrane dynamics that was enabled by trehalose-fluorophore conjugates capable of labeling trehalose glycolipids in live actinomycetes. We identified fluorescein-trehalose analogs that are metabolically incorporated into the trehalose mycolates of representative Mycobacterium, Corynebacterium, Nocardia and Rhodococcus species...
January 11, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28069810/sensitive-versatile-fluorogenic-transmembrane-peptide-substrates-for-rhomboid-intramembrane-proteases
#8
Anežka Tichá, Stancho Stanchev, Jan Škerle, Jakub Began, Marek Ingr, Kateř Ina Švehlová, Lucie Polovinkin, Martin Růžička, Lucie Bednárová, Romana Hadravová, Edita Poláchová, Petra Rampírová, Jana Březinová, Václav Kašička, Pavel Majer, Kvido Strisovsky
Rhomboid proteases are increasingly being explored as potential drug targets, but their potent and specific inhibitors are not available, and strategies for inhibitor development are hampered by the lack of widely usable and easily modifiable in vitro activity assays. Here we address this bottleneck and report on the development of new fluorogenic transmembrane peptide substrates, which are cleaved by several unrelated rhomboid proteases, can be used both in detergent micelles and in liposomes, and contain red-shifted fluorophores that are suitable for high-throughput screening of compound libraries...
January 9, 2017: Journal of Biological Chemistry
https://www.readbyqxmd.com/read/28069502/synthesis-and-characterization-of-citrate-based-fluorescent-small-molecules-and-biodegradable-polymers
#9
Zhiwei Xie, Jimin P Kim, Qing Cai, Yi Zhang, Jinshan Guo, Ranjodh S Dhami, LiLi, Bin Kong, Yixue Su, Kevin A Schug, Jian Yang
Novel citric acid based photoluminescent dyes and degradable polymers are synthesized via a facile "one-pot" reaction. A comprehensive understanding of the fluorescence mechanisms of the resulting citric acid-based fluorophores is reported. Two distinct types of fluorophores are identified: a thiozolopyridine family with high quantum yield, long lifetime, and exceptional photostability, and a dioxopyridine family with relatively lower quantum yield, multiple lifetimes, and solvent-dependent band shifting behavior...
January 6, 2017: Acta Biomaterialia
https://www.readbyqxmd.com/read/28068315/hyperspectral-phasor-analysis-enables-multiplexed-5d-in-vivo-imaging
#10
Francesco Cutrale, Vikas Trivedi, Le A Trinh, Chi-Li Chiu, John M Choi, Marcela S Artiga, Scott E Fraser
Time-lapse imaging of multiple labels is challenging for biological imaging as noise, photobleaching and phototoxicity compromise signal quality, while throughput can be limited by processing time. Here, we report software called Hyper-Spectral Phasors (HySP) for denoising and unmixing multiple spectrally overlapping fluorophores in a low signal-to-noise regime with fast analysis. We show that HySP enables unmixing of seven signals in time-lapse imaging of living zebrafish embryos.
January 9, 2017: Nature Methods
https://www.readbyqxmd.com/read/28067855/detection-of-naja-atra-cardiotoxin-using-adenosine-based-molecular-beacon
#11
Yi-Jun Shi, Ying-Jung Chen, Wan-Ping Hu, Long-Sen Chang
This study presents an adenosine (A)-based molecular beacon (MB) for selective detection of Naja atra cardiotoxin (CTX) that functions by utilizing the competitive binding between CTX and the poly(A) stem of MB to coralyne. The 5'- and 3'-end of MB were labeled with a reporter fluorophore and a non-fluorescent quencher, respectively. Coralyne induced formation of the stem-loop MB structure through A₂-coralyne-A₂ coordination, causing fluorescence signal turn-off due to fluorescence resonance energy transfer between the fluorophore and quencher...
January 7, 2017: Toxins
https://www.readbyqxmd.com/read/28067802/stabilization-of-nucleosomes-by-histone-tails-and-by-fact-revealed-by-spfret-microscopy
#12
Maria E Valieva, Nadezhda S Gerasimova, Kseniya S Kudryashova, Anastasia L Kozlova, Mikhail P Kirpichnikov, Qi Hu, Maria Victoria Botuyan, Georges Mer, Alexey V Feofanov, Vasily M Studitsky
A correct chromatin structure is important for cell viability and is tightly regulated by numerous factors. Human protein complex FACT (facilitates chromatin transcription) is an essential factor involved in chromatin transcription and cancer development. Here FACT-dependent changes in the structure of single nucleosomes were studied with single-particle Förster resonance energy transfer (spFRET) microscopy using nucleosomes labeled with a donor-acceptor pair of fluorophores, which were attached to the adjacent gyres of DNA near the contact between H2A-H2B dimers...
January 6, 2017: Cancers
https://www.readbyqxmd.com/read/28067769/identification-of-a-potent-allosteric-inhibitor-of-human-protein-kinase-ck2-by-bacterial-surface-display-library-screening
#13
Christian Nienberg, Claudia Garmann, Andreas Gratz, Andre Bollacke, Claudia Götz, Joachim Jose
Human protein kinase CK2 has emerged as promising target for the treatment of neoplastic diseases. The vast majority of kinase inhibitors known today target the ATP binding site, which is highly conserved among kinases and hence leads to limited selectivity. In order to identify non-ATP competitive inhibitors, a 12-mer peptide library of 6 × 10⁵ variants was displayed on the surface of E. coli by autodisplay. Screening of this peptide library on variants with affinity to CK2 was performed by fluorophore-conjugated CK2 and subsequent flow cytometry...
January 5, 2017: Pharmaceuticals
https://www.readbyqxmd.com/read/28067438/chemoselective-reactions-for-the-synthesis-of-glycoconjugates-from-unprotected-carbohydrates
#14
Klaus Villadsen, Manuel C Martos-Maldonado, Knud J Jensen, Mikkel Boas Thygesen
Glycobiology is the comprehensive biological investigation of carbohydrates. The study of the role and function of complex carbohydrates often requires the attachment of carbohydrates to surfaces, their tagging with fluorophores, or conversion into natural or non-natural glycoconjugates, such as glycopeptides or -lipids. Glycobiology and its 'omics', glycomics, require easy and robust chemical methods for the construction of these glycoconjugates. This review gives an overview of the rapidly expanding field of chemical reactions that selectively convert unprotected carbohydrates into glycoconjugates through the anomeric position...
January 9, 2017: Chembiochem: a European Journal of Chemical Biology
https://www.readbyqxmd.com/read/28064458/label-free-multiphoton-microscopy-reveals-altered-tissue-architecture-in-hippocampal-sclerosis
#15
Ortrud Uckermann, Roberta Galli, Susann Leupold, Roland Coras, Matthias Meinhardt, Susanne Hallmeyer-Elgner, Thomas Mayer, Alexander Storch, Gabriele Schackert, Edmund Koch, Ingmar Blümcke, Gerald Steiner, Matthias Kirsch
The properties and structure of tissue can be visualized without labeling or preparation by multiphoton microscopy combining coherent anti-Stokes Raman scattering (CARS), addressing lipid content, second harmonic generation (SHG) showing collagen, and two-photon excited fluorescence (TPEF) of endogenous fluorophores. We compared samples of sclerotic and nonsclerotic human hippocampus to detect pathologic changes in the brain of patients with pharmacoresistant temporomesial epilepsy (n = 15). Multiphoton microscopy of cryosections and bulk tissue revealed hippocampal layering and micromorphologic details in accordance with reference histology: CARS displayed white and gray matter layering and allowed the assessment of axonal myelin...
January 2017: Epilepsia
https://www.readbyqxmd.com/read/28064073/exploring-the-effect-of-bisphenol-s-on-sludge-hydrolysis-and-mechanism-of-the-interaction-between-bisphenol-s-and-%C3%AE-amylase-through-spectrophotometric-methods
#16
Hang Yang, Guangying Hou, Li Zhang, Lei Ju, Chunguang Liu
Sewage sludge, as a very significant sources of BPS (up to 523mg/kg dw) introduction into the environment, must be handled properly. Therefore, it is important to access BPS removal and its effect on sludge treatment with the biological treatment. However, it is unclear for its effect on the hydrolysis of sludge. In this research, impact of BPS on sludge hydrolysis by α-Amylase is studied from the respect of component of soluble organic matter in sludge using three-dimensional fluorescence spectra. Enzyme activity assay suggests that sludge hydrolysis is inhibited due to the denaturation of α-Amylase with BPS exposure...
December 22, 2016: Journal of Photochemistry and Photobiology. B, Biology
https://www.readbyqxmd.com/read/28064068/the-naphthoate-modifying-cu-2-detective-bodipy-sensors-with-the-fluorescent-on-off-performance-unaffected-by-molecular-configuration
#17
Yuting Chen, Luyang Zhao, Jianzhuang Jiang
Two new boron-dipyrromethenes decorated with 8-hydroxyquinoline-naphthoate moiety, namely 4,4-difluoro-8-(5-(8-hydroxyquinoline-naphthoate))-3,5-dimethyl-4-bora-3a,4a-diaza-s-indacene (8-HQ-N-DMe-Bodipy) (1) and 4,4-difluoro-8-(5-(8-hydroxyquinoline-naphthoate))-1,3,5,7-tetramethyl-4-bora-3a,4a-diaza-s-indacene (8-HQ-N-TMe-Bodipy) (2) have been synthesized. Single crystal X-ray diffraction analysis discloses the very much similar steric arrangement of 8-hydroxyquinoline-naphthoate moiety in these two compounds as revealed by the close torsion angle of C-C-O-C bridge, 174...
December 21, 2016: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
https://www.readbyqxmd.com/read/28063491/fluorescence-based-in-situ-quantitative-imaging-for-cellular-lipids
#18
W Cho, Y Yoon, S-L Liu, K Baek, R Sheng
Membrane lipids are dynamic molecules and their local concentrations serve as regulatory signals for diverse biological processes. To achieve quantitative in situ imaging of various lipids, we developed a ratiometric analysis using fluorescence biosensors, each of which is composed of an engineered lipid-binding protein and a covalently attached solvatochromic fluorophore. To cover a wide range of lipid concentration, lipid-binding proteins are engineered to have variable dynamic ranges. These tunable sensors allow robust and sensitive in situ quantitative lipid imaging in mammalian cells, providing new insight into the spatiotemporal dynamics and fluctuation of key signaling lipids...
2017: Methods in Enzymology
https://www.readbyqxmd.com/read/28062034/integrating-optical-tweezers-dna-tightropes-and-single-molecule-fluorescence-imaging-pitfalls-and-traps
#19
J Wang, J T Barnett, M R Pollard, N M Kad
Fluorescence imaging is one of the cornerstone techniques for understanding how single molecules search for their targets on DNA. By tagging individual proteins, it is possible to track their position with high accuracy. However, to understand how proteins search for targets, it is necessary to elongate the DNA to avoid protein localization ambiguities. Such structures known as "DNA tightropes" are tremendously powerful for imaging target location; however, they lack information about how force and load affect protein behavior...
2017: Methods in Enzymology
https://www.readbyqxmd.com/read/28060890/developing-and-testing-a-bayesian-analysis-of-fluorescence-lifetime-measurements
#20
Bryan Kaye, Peter J Foster, Tae Yeon Yoo, Daniel J Needleman
FRET measurements can provide dynamic spatial information on length scales smaller than the diffraction limit of light. Several methods exist to measure FRET between fluorophores, including Fluorescence Lifetime Imaging Microscopy (FLIM), which relies on the reduction of fluorescence lifetime when a fluorophore is undergoing FRET. FLIM measurements take the form of histograms of photon arrival times, containing contributions from a mixed population of fluorophores both undergoing and not undergoing FRET, with the measured distribution being a mixture of exponentials of different lifetimes...
2017: PloS One
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