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Forster resonance energy transfer

Michael R Hamblin
Photodynamic therapy (PDT) involves the combination of non-toxic dyes called photosensitizers (PS) and harmless visible light that interact with ambient oxygen to give reactive oxygen species (ROS) that can damage biomolecules and kill cells. PDT has mostly been developed as a cancer therapy but can also be used as an antimicrobial approach against localized infections. However even the longest wavelength used for exciting PS (in the 700 nm region) has relatively poor tissue penetration, and many PS are much better excited by blue and green light...
February 16, 2018: Dalton Transactions: An International Journal of Inorganic Chemistry
Satoshi Takahashi, Aya Yoshida, Hiroyuki Oikawa
We propose a hypothesis that explains two apparently contradicting observations for the heterogeneity of the unfolded proteins. First, the line confocal method of the single-molecule Förster resonance energy transfer (sm-FRET) spectroscopy revealed that the unfolded proteins possess broad peaks in the FRET efficiency plot, implying the significant heterogeneity that lasts longer than milliseconds. Second, the fluorescence correlation method demonstrated that the unfolded proteins fluctuate in the time scale shorter than 100 ns...
February 14, 2018: Biophysical Reviews
Anna M Chizhik, Carina Wollnik, Daja Ruhlandt, Narain Karedla, Alexey I Chizhik, Lara Hauke, Dirk Hähnel, Ingo Gregor, Jörg Enderlein, Florian Rehfeldt
We report a novel method, dual color axial nanometric localization by Metal Induced Energy Transfer (dcMIET), and combine it with Förster Resonant Energy Transfer (FRET) for resolving structural details in cells on the molecular level. We demonstrate the capability of this method on cytoskeletal elements and adhesions in human mesenchymal stem cells (hMSCs). Our approach is based on Fluorescence-Lifetime-Imaging Microscopy (FLIM), and allows for precise determination of the 3D architecture of stress fibers anchoring at focal adhesions, thus yielding crucial information to understand cell-matrix mechanics...
February 14, 2018: Molecular Biology of the Cell
Markus Götz, Philipp Wortmann, Sonja Schmid, Thorsten Hugel
Single-molecule Förster resonance energy transfer (smFRET) has become a widely used biophysical technique to study the dynamics of biomolecules. For many molecular machines in a cell proteins have to act together with interaction partners in a functional cycle to fulfill their task. The extension of two-color to multi-color smFRET makes it possible to simultaneously probe more than one interaction or conformational change. This not only adds a new dimension to smFRET experiments but it also offers the unique possibility to directly study the sequence of events and to detect correlated interactions when using an immobilized sample and a total internal reflection fluorescence microscope (TIRFM)...
January 30, 2018: Journal of Visualized Experiments: JoVE
Gulam Rabbani, Eun Ju Lee, Khurshid Ahmad, Mohammad Hassan Baig, Inho Choi
Tolperisone hydrochloride (TH) has muscle relaxant activity, and has been widely used for several years in clinical practice to treat pathologically high skeletal muscle tone (spasticity) and related pains. The current study was designed to explore the binding efficacy of TH with human serum albumin (HSA) using a multispectroscopic approach, FRET, esterase-like activity, and a molecular docking method. A reduction in fluorescence emission at 340 nm of HSA was attributed to florescence quenching by TH via a static quenching type...
February 12, 2018: Molecular Pharmaceutics
Anja Paulick, Victor Sourjik
Most motile bacteria follow spatial gradients of chemical and physical stimuli in their environment. In Escherichia coli and other bacteria, the best characterized chemotaxis is in gradients of amino acids or sugars, but other physiological stimuli such as pH, osmolarity, redox potentials, and temperature are also known to elicit tactic responses. These multiple environmental stimuli are integrated and processed within a highly sophisticated chemotaxis network to generate coordinated chemotaxis behavior, which features high sensitivity, a wide dynamic range, and robustness against variations in background stimulation, protein levels, and temperature...
2018: Methods in Molecular Biology
Kaleeckal G Harikumar, Yan Yan, Ting-Hai Xu, Karsten Melcher, H Eric Xu, Laurence J Miller
The bioluminescence resonance energy transfer (BRET) assay can be used as an indicator of molecular approximation and/or interaction. A significant resonance energy transfer signal is generated when the acceptor, having the appropriate spectral overlap with the donor emission, is approximated with the donor. In the example provided, proteins tagged with bioluminescent Renilla luciferase (Rlu) as donor and yellow fluorescent protein (YFP) as acceptor were co-expressed in cells. This pair of donor and acceptor have an approximate Förster distance of 4...
November 20, 2017: Bio-protocol
Michael E Fealey, Benjamin P Binder, Vladimir N Uversky, Anne Hinderliter, David D Thomas
We used time-resolved Förster resonance energy transfer, circular dichroism, and molecular dynamics simulation to investigate the structural dependence of synaptotagmin 1's intrinsically disordered region (IDR) on phosphorylation and dielectric constant. We found that a peptide corresponding to the full-length IDR sequence, a ∼60-residue strong polyampholyte, can sample structurally collapsed states in aqueous solution, consistent with its κ-predicted behavior, where κ is a sequence-dependent parameter that is used to predict IDR compaction...
February 6, 2018: Biophysical Journal
Gabriel Bidaux, Corentin Le Nézet, Mariano Gonzalez Pisfil, Mélanie Henry, Alessandro Furlan, Oliver Bensaude, Bernard Vandenbunder, Laurent Héliot
Biochemical studies have revealed that the RNA Polymerase II (RNAPII) pause release is triggered by phosphorylation of the transcription machinery by the positive transcription elongation factor b (P-TEFb). However, there are no direct report that P-TEFb and RNA polymerase II interact in single living cells and the biophysical mechanisms mediating this association are still unclear. Förster resonance energy transfer (FRET) detects molecular interactions at the subcellular level. Time domain fluorescence lifetime imaging provides an accurate quantification of FRET efficiency, EFRET, because it is fluorochrome concentration-independent and insensitive to fluorescence bleed-through...
February 6, 2018: Biophysical Journal
Samie R Jaffrey
Genetically encoded sensors are important tools for measuring metabolites and other small molecules in vitro and in live cells. Until recently, genetically encoded sensors exclusively comprised fluorescent proteins that undergo changes in Förster resonance energy transfer upon binding a target analyte. However, recently a new class of fluorescent sensor has been developed composed of RNA. These RNA-based sensors rely on Spinach and other RNA mimics of green fluorescent protein. In each case, the RNA-based sensors contain an analyte-binding aptamer domain which transduces binding of the analyte into a conformational change in Spinach...
2018: Advances in Pharmacology
Ying Nan Zhang, Yu Sheng Liu, Min Ming Yan, You Wei, Qi Lun Zhang, Yong Zhang
The utilization of triplet excitons plays a key role in obtaining highly efficient quantum-dot light-emitting diodes (QD-LEDs). However, to date, only phosphorescent materials have been implemented to harvest the triplet excitons in QD-LEDs. In this work, we introduced a thermally activated delayed fluorescence (TADF) emitter, 4,5-di(9H-carbazol-9-yl)phthalonitrile (2CzPN), doped into poly(N-vinylcarbazole) (PVK) as exciton harvester in red QD-LEDs by solution-processed. As a result, electrons leaking to PVK layer will be trapped by 2CzPN to form long lifetime TADF excitons in 2CzPN:PVK layer and then these harvesting exciton energy can be effectively transferred to the adjacent QDs by Förster resonance energy transfer process...
February 7, 2018: ACS Applied Materials & Interfaces
Bárbara Gomes, Sónia Gonçalves, Anibal Disalvo, Axel Hollmann, Nuno C Santos
Recently, it was demonstrated that 25-hydroxycholesterol (25HC), an oxidized cholesterol derivative, inhibits human immunodeficiency virus type 1 (HIV) entry into its target cells. However, the mechanisms involved in this action have not yet been established. The aim of this work was to study the effects of 25HC in biomembrane model systems and at the level of HIV fusion peptide (HIV-FP). Integration of different biophysical approaches was made in the context of HIV fusion process, to clarify the changes at membrane level due to the presence of 25HC that result in the suppressing viral infection...
February 2, 2018: Biochimica et Biophysica Acta
Simone Brand, Yao-Wen Wu
Förster resonance energy transfer (FRET) probes are powerful tools to monitor protein-protein interactions and enzyme activities in a spatiotemporal manner in live cells. Using a combination of noncanonical amino acid (ncAA) mutagenesis and bioorthogonal labeling, we have developed intramolecular FRET probes consisting of a fluorescent protein and an organic dye within an individual protein. Herein we present a general approach to establish intramolecular FRET probes for imaging of protein activity in live cells...
2018: Methods in Molecular Biology
Hae Won Sohn, Joseph Brzostowski
For decades, various Förster resonance energy transfer (FRET) techniques have been developed to measure the distance between interacting molecules. FRET imaging by the sensitized acceptor emission method has been widely applied to study the dynamical association between two molecules at a nanometer scale in live cells. Here, we provide a detailed protocol for FRET imaging by sensitized emission using a confocal laser scanning microscope to analyze the interaction of the B cell receptor (BCR) with the Lyn-enriched lipid microdomain on the plasma membrane of live cells upon antigen binding, one of the earliest signaling events in BCR-mediated B cell activation...
2018: Methods in Molecular Biology
Ting Xiao, Jian Sun, Jiahui Zhao, Shuang Wang, Guoyong Liu, Xiurong Yang
As an essential and universal hydrolase, alkaline phosphatase (ALP) has been identified as a crucial indicator of various diseases. Herein, we for the first time expanded the application of fluorescent polydopamine (F-PDA) nanoparticles to nanoquencher-based biosensing system, as well as we discovered the reversible quenching effect of manganese dioxide (MnO2) nanosheets on the fluorescence of F-PDA nanoparticles and intensively confirmed the quenching mechanism of Förster resonance energy transfer (FRET) by using TEM, UV/vis, FT-IR spectroscopy and fluorescence lifetime experiments...
January 31, 2018: ACS Applied Materials & Interfaces
Daniëlle R J Verboogen, Maksim V Baranov, Martin Ter Beest, Geert van den Bogaart
Soluble N-ethylmaleimide sensitive fusion protein (NSF) attachment protein receptor (SNARE) proteins are key for membrane trafficking, as they catalyze membrane fusion within eukaryotic cells. The SNARE protein family consists of about 36 different members. Specific intracellular transport routes are catalyzed by specific sets of 3 or 4 SNARE proteins that thereby contribute to the specificity and fidelity of membrane trafficking. However, studying the precise function of SNARE proteins is technically challenging, because SNAREs are highly abundant and functionally redundant, with most SNAREs having multiple and overlapping functions...
December 29, 2017: Journal of Visualized Experiments: JoVE
Burhan Gulbahar, Gorkem Memisoglu
Biological particle tracking systems monitor cellular processes or particle behaviors with the great accuracy. The emissions of fluorescent molecules or direct images of particles are captured with cameras or photodetectors. The current imaging systems have challenges in detection, collection, and analysis of imaging data, penetration depth, and complicated set-ups. In this paper, a signaling-based nanoscale acousto-optic radar and microfluidic multiple particle tracking (MPT) system is proposed based on the theoretical design providing nanoscale optical modulator with vibrating Förster resonance energy transfer and vibrating cadmium selenide/zinc sulfide quantum dots (QDs) on graphene resonators...
December 2017: IEEE Transactions on Nanobioscience
Samsuzzoha Mondal, Amitava Chandra, Ravindra Venkatramani, Ankona Datta
We present a systematic experimental and computational study of phospholipid induced peptide coil-helix transitions which are relevant in the context of proteins mediating cytoskeletal rearrangement via membrane binding. We developed a sensitive Förster resonance energy transfer (FRET) based assay to address whether coil-helix transitions in phospholipid binding motifs of actin-binding proteins can be induced by physiologically-relevant concentrations (1-20 μM) of phosphatidylinositol-4,5-bisphosphate (PI(4,5)P2) phospholipids...
January 24, 2018: Faraday Discussions
Amjad Horani, Alessandro Ustione, Tao Huang, Amy L Firth, Jiehong Pan, Sean P Gunsten, Jeffrey A Haspel, David W Piston, Steven L Brody
Motile cilia are characterized by dynein motor units, which preassemble in the cytoplasm before trafficking into the cilia. Proteins required for dynein preassembly were discovered by finding human mutations that result in absent ciliary motors, but little is known about their expression, function, or interactions. By monitoring ciliogenesis in primary airway epithelial cells and MCIDAS-regulated induced pluripotent stem cells, we uncovered two phases of expression of preassembly proteins. An early phase, composed of HEATR2, SPAG1, and DNAAF2, preceded other preassembly proteins and was independent of MCIDAS regulation...
January 22, 2018: Proceedings of the National Academy of Sciences of the United States of America
Kazuhiro Maeshima, Tomoki Matsuda, Yutaka Shindo, Hiromi Imamura, Sachiko Tamura, Ryosuke Imai, Syoji Kawakami, Ryosuke Nagashima, Tomoyoshi Soga, Hiroyuki Noji, Kotaro Oka, Takeharu Nagai
For cell division, negatively charged chromatin, in which nucleosome fibers (10 nm fibers) are irregularly folded [1-5], must be condensed into chromosomes and segregated. While condensin and other proteins are critical for organizing chromatin into the appropriate chromosome shape [6-17], free divalent cations such as Mg2+ and Ca2+, which condense chromatin or chromosomes in vitro [18-28], have long been considered important, especially for local condensation, because the nucleosome fiber has a net negative charge and is by itself stretched like "beads on a string" by electrostatic repulsion...
January 15, 2018: Current Biology: CB
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