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https://www.readbyqxmd.com/read/28431243/cryo-em-structure-of-the-open-human-ether-%C3%A3-go-go-related-k-channel-herg
#1
Weiwei Wang, Roderick MacKinnon
The human ether-à-go-go-related potassium channel (hERG, Kv11.1) is a voltage-dependent channel known for its role in repolarizing the cardiac action potential. hERG alteration by mutation or pharmacological inhibition produces Long QT syndrome and the lethal cardiac arrhythmia torsade de pointes. We have determined the molecular structure of hERG to 3.8 Å using cryo-electron microscopy. In this structure, the voltage sensors adopt a depolarized conformation, and the pore is open. The central cavity has an atypically small central volume surrounded by four deep hydrophobic pockets, which may explain hERG's unusual sensitivity to many drugs...
April 20, 2017: Cell
https://www.readbyqxmd.com/read/28428547/the-tarantula-toxin-%C3%AE-%C3%AE-trtx-pre1a-highlights-the-importance-of-the-s1-s2-voltage-sensor-region-for-sodium-channel-subtype-selectivity
#2
Joshua S Wingerd, Christine A Mozar, Christine A Ussing, Swetha S Murali, Yanni K-Y Chin, Ben Cristofori-Armstrong, Thomas Durek, John Gilchrist, Christopher W Vaughan, Frank Bosmans, David J Adams, Richard J Lewis, Paul F Alewood, Mehdi Mobli, Macdonald J Christie, Lachlan D Rash
Voltage-gated sodium (NaV) channels are essential for the transmission of pain signals in humans making them prime targets for the development of new analgesics. Spider venoms are a rich source of peptide modulators useful to study ion channel structure and function. Here we describe β/δ-TRTX-Pre1a, a 35-residue tarantula peptide that selectively interacts with neuronal NaV channels inhibiting peak current of hNaV1.1, rNaV1.2, hNaV1.6, and hNaV1.7 while concurrently inhibiting fast inactivation of hNaV1.1 and rNaV1...
April 20, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28427612/study-of-ultrasonic-cavitation-during-extraction-of-the-peanut-oil-at-varying-frequencies
#3
Lei Zhang, Cunshan Zhou, Bei Wang, Abu El-Gasim A Yagoub, Haile Ma, Xiao Zhang, Mian Wu
The ultrasonic extraction of oils is a typical physical processing technology. The extraction process was monitored from the standpoint of the oil quality and efficiency of oil extraction. In this study, the ultrasonic cavitation fields were measured by polyvinylidene fluoride (PVDF) sensor. Waveform of ultrasonic cavitation fields was gained and analyzed. The extraction yield and oxidation properties were compared. The relationship between the fields and cavitation oxidation was established. Numerical calculation of oscillation cycle was done for the cavitation bubbles...
July 2017: Ultrasonics Sonochemistry
https://www.readbyqxmd.com/read/28424589/the-calcium-channel-c-terminal-and-synaptic-vesicle-tethering-analysis-by-immuno-nanogold-localization
#4
Robert H C Chen, Qi Li, Christine A Snidal, Sabiha R Gardezi, Elise F Stanley
At chemical synapses the incoming action potential triggers the influx of Ca(2+) through voltage-sensitive calcium channels (CaVs, typically CaV2.1 and 2.2) and the ions binds to sensors associated with docked, transmitter filled synaptic vesicles (SVs), triggering their fusion and discharge. The CaVs and docked SVs are located within the active zone (AZ) region of the synapse which faces a corresponding neurotransmitter receptor-rich region on the post-synaptic cell. Evidence that the fusion of a SV can be gated by Ca(2+) influx through a single CaV suggests that the channel and docked vesicle are linked by one or more molecular tethers (Stanley, 1993)...
2017: Frontiers in Cellular Neuroscience
https://www.readbyqxmd.com/read/28422485/fabrication-of-a-highly-sensitive-single-aligned-tio2-and-gold-nano-particle-embedded-tio2-nano-fiber-gas-sensor
#5
Alireza Nikfarjam, Seyedsina Hosseini, Nahideh Salehifar
In this research, a single-aligned nanofiber of pure TiO2 and Gold nano-particle (GNP)-TiO2 was fabricated using a novel electro-spinning procedure equipped with secondary electrostatic fields on highly sharp triangular and rectangular electrodes provided for gas sensing applications. The Sol used for spinning nanofiber consisted of Titanium Tetraisopropoxide (C12H28O4Ti), Acetic Acid (CH3COOH), Ethanol (C2H5OH) and Polyvinylpyrrolidone (PVP) and gold nanoparticle solution. FE-SEM, TEM, and XRD were used to characterize the single nanofiber...
April 19, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28422068/a-low-cost-bluetooth-low-energy-transceiver-for-wireless-sensor-network-applications-with-a-front-end-receiver-matching-network-reusing-power-amplifier-load-inductor
#6
Zhen Liang, Bin Li, Mo Huang, Yanqi Zheng, Hui Ye, Ken Xu, Fangming Deng
In this work, a low cost Bluetooth Low Energy (BLE) transceiver for wireless sensor network (WSN) applications, with a receiver (RX)-matching network-reusing power amplifier (PA) load inductor, is presented. In order to decrease the die area, only two inductors were used in this work. Besides the one used in the voltage control oscillator (VCO), the PA load inductor was reused as the RX impedance matching component in the front-end. Proper controls have been applied to achieve high transmitter (TX) input impedance when the transceiver is in the receiving mode, and vice versa...
April 19, 2017: Sensors
https://www.readbyqxmd.com/read/28422061/the-effect-of-particles-on-electrolytically-polymerized-thin-natural-mcf-rubber-for-soft-sensors-installed-in-artificial-skin
#7
Kunio Shimada, Osamu Mochizuki, Yoshihiro Kubota
The aim of this study is to investigate the effect of particles as filler in soft rubber sensors installed in artificial skin. We examine sensors made of natural rubber (NR-latex) that include magnetic particles of Ni and Fe₃O₄ using magnetic compound fluid (MCF). The 1-mm thickness of the electrolytically polymerized MCF rubber makes production of comparatively thin rubber sensors feasible. We first investigate the effect of magnetic particles Ni and Fe₃O₄ on the curing of MCF rubber. Next, in order to adjust the electric properties of the MCF rubber, we adopt Al₂O₃ dielectric particles...
April 19, 2017: Sensors
https://www.readbyqxmd.com/read/28420169/ultrasensitive-label-free-sensing-of-il-6-based-on-pase-functionalized-carbon-nanotube-micro-arrays-with-rna-aptamers-as-molecular-recognition-elements
#8
Farhad Khosravi, Seyed Masoud Loeian, Balaji Panchapakesan
This study demonstrates the rapid and label-free detection of Interleukin-6 (IL-6) using carbon nanotube micro-arrays with aptamer as the molecular recognition element. Single wall carbon nanotubes micro-arrays biosensors were manufactured using photo-lithography, metal deposition, and etching techniques. Nanotube biosensors were functionalized with 1-Pyrenebutanoic Acid Succinimidyl Ester (PASE) conjugated IL-6 aptamers. Real time response of the sensor conductance was monitored with increasing concentration of IL-6 (1 pg/mL to 10 ng/mL), exposure to the sensing surface in buffer solution, and clinically relevant spiked blood samples...
April 17, 2017: Biosensors
https://www.readbyqxmd.com/read/28420132/a-smart-voltage-and-current-monitoring-system-for-three-phase-inverters-using-an-android-smartphone-application
#9
Mohannad Jabbar Mnati, Alex Van den Bossche, Raad Farhood Chisab
In this paper, a new smart voltage and current monitoring system (SVCMS) technique is proposed. It monitors a three phase electrical system using an Arduino platform as a microcontroller to read the voltage and current from sensors and then wirelessly send the measured data to monitor the results using a new Android application. The integrated SVCMS design uses an Arduino Nano V3.0 as the microcontroller to measure the results from three voltage and three current sensors and then send this data, after calculation, to the Android smartphone device of an end user using Bluetooth HC-05...
April 15, 2017: Sensors
https://www.readbyqxmd.com/read/28416203/the-s4-s5-linker-gearbox-of-trp-channel-gating
#10
REVIEW
Laura Hofmann, Hongmei Wang, Wang Zheng, Stephan E Philipp, Patricia Hidalgo, Adolfo Cavalié, Xing-Zhen Chen, Andreas Beck, Veit Flockerzi
Transient receptor potential (TRP) channels are cation channels which participate in a wide variety of physiological processes in organisms ranging from fungi to humans. They fulfill roles in body homeostasis, are sensors for noxious chemicals and temperature in the mammalian somatosensory system and are activated by light stimulated phospholipase C activity in Drosophila or by hypertonicity in yeast. The transmembrane topology of TRP channels is similar to that of voltage-gated cation channels. TRP proteins assemble as tetramers with each subunit containing six transmembrane helices (S1-S6) and intracellular N- and C-termini...
April 4, 2017: Cell Calcium
https://www.readbyqxmd.com/read/28408328/trpa1-expression-levels-and-excitability-brake-by-kv-channels-influence-cold-sensitivity-of-trpa1-expressing-neurons
#11
Tosifa Memon, Kevin Chase, Lee S Leavitt, Baldomero M Olivera, Russell W Teichert
The molecular sensor of innocuous (painless) cold sensation is well-established to be transient receptor potential cation channel, subfamily M, member 8 (TRPM8). However, the role of transient receptor potential cation channel, subfamily A, member 1 (TRPA1) in noxious (painful) cold sensation has been controversial. We find that TRPA1 channels contribute to the noxious cold sensitivity of mouse somatosensory neurons, independent of TRPM8 channels, and that TRPA1-expressing neurons are largely non-overlapping with TRPM8-expressing neurons in mouse dorsal-root ganglia (DRG)...
April 10, 2017: Neuroscience
https://www.readbyqxmd.com/read/28406893/the-chemical-basis-for-electrical-signaling
#12
REVIEW
William A Catterall, Goragot Wisedchaisri, Ning Zheng
Electrical signals generated by minute currents of ions moving across cell membranes are central to all rapid processes in biology. Initiation and propagation of electrical signals requires voltage-gated sodium (NaV) and calcium (CaV) channels. These channels contain a tetramer of membrane-bound subunits or domains comprising a voltage sensor and a pore module. Voltage-dependent activation occurs as membrane depolarization drives outward movements of positive gating changes in the voltage sensor via a sliding-helix mechanism, which leads to a conformational change in the pore module that opens its intracellular activation gate...
April 13, 2017: Nature Chemical Biology
https://www.readbyqxmd.com/read/28402882/gating-charge-calculations-by-computational-electrophysiology-simulations
#13
Jan-Philipp Machtens, Rodolfo Briones, Claudia Alleva, Bert L de Groot, Christoph Fahlke
Electrical cell signaling requires adjustment of ion channel, receptor, or transporter function in response to changes in membrane potential. For the majority of such membrane proteins, the molecular details of voltage sensing remain insufficiently understood. Here, we present a molecular dynamics simulation-based method to determine the underlying charge movement across the membrane-the gating charge-by measuring electrical capacitor properties of membrane-embedded proteins. We illustrate the approach by calculating the charge transfer upon membrane insertion of the HIV gp41 fusion peptide, and validate the method on two prototypical voltage-dependent proteins, the Kv1...
April 11, 2017: Biophysical Journal
https://www.readbyqxmd.com/read/28400471/a-novel-tarantula-toxin-stabilizes-the-deactivated-voltage-sensor-of-bacterial-sodium-channel
#14
Cheng Tang, Xi Zhou, Phuong Tran Nguyen, Yunxiao Zhang, Zhaotun Hu, Changxin Zhang, Vladimir Yarov-Yarovoy, Paul G DeCaen, Songping Liang, Zhonghua Liu
Voltage-gated sodium channels (NaVs) are activated by transiting the voltage sensor from the deactivated to the activated state. The crystal structures of several bacterial NaVs have captured the voltage sensor module (VSM) in an activated state, but structure of the deactivated voltage sensor remains elusive. In this study, we sought to identify peptide toxins stabilizing the deactivated VSM of bacterial NaVs. We screened fractions from several venoms and characterized a cystine knot toxin called JZTx-27 from the venom of tarantula Chilobrachys jingzhao as a high-affinity antagonist of the prokaryotic NaVs nonselective voltage-gated, Bacillus alcalophilus (NsVBa) and bacterial sodium channel from Bacillus halodurans(NaChBac) (IC50 = 112 nM and 30 nM, respectively)...
April 11, 2017: FASEB Journal: Official Publication of the Federation of American Societies for Experimental Biology
https://www.readbyqxmd.com/read/28398555/biophysical-and-functional-characterization-of-hippocalcin-mutants-responsible-for-human-dystonia
#15
Nordine Helassa, Svetlana V Antonyuk, Lu-Yun Lian, Lee P Haynes, Robert D Burgoyne
Dystonia is a neurological movement disorder that forces the body into twisting, repetitive movements or sometimes painful abnormal postures. With the advent of next-generation sequencing technologies, the homozygous mutations T71N and A190T in the neuronal calcium sensor (NCS) hippocalcin were identified as the genetic cause of primary isolated dystonia (DYT2 dystonia). However, the effect of these mutations on the physiological role of hippocalcin has not yet been elucidated. Using a multidisciplinary approach, we demonstrated that hippocalcin oligomerises in a calcium-dependent manner and binds to voltage-gated calcium channels...
April 7, 2017: Human Molecular Genetics
https://www.readbyqxmd.com/read/28397819/size-dependent-magnetic-tuning-of-lateral-photovoltaic-effect-in-nonmagnetic-si-based-schottky-junctions
#16
Peiqi Zhou, Zhikai Gan, Xu Huang, Chunlian Mei, Yuxing Xia, Hui Wang
In this article, we report a magnetic tuning lateral photovoltaic effect (LPE) in a nonmagnetic Si-based Schottky junctions. In the magnetic field intensity range of 0 to 1.6 T, the variation amplitude of LPE sensitivity is as high as 94.8%, the change of LPV is and the change rate of lateral photo-voltage even reaches 520 mV/T at 1.5 T, which is apparently higher than the results of previous reported researches in magnetic materials. This effect is attributed to the combined result of the influence of magnetic field on diffusion current and the rectification property of our anisotropic structure...
April 11, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28387114/light-induced-conformational-changes-of-lov2-kinase-and-the-linker-region-in-arabidopsis-phototropin2
#17
Akira Takakado, Yusuke Nakasone, Koji Okajima, Satoru Tokutomi, Masahide Terazima
Phototropins (phots) are blue light sensors found in a variety of higher plants and algae. The photochemical reactions of this family of proteins have attracted much attention since their discovery. Phots have two light sensor domains called light-oxygen-voltage 1 (LOV1) and LOV2. After the formation of the characteristic adduct of the LOV domain, a conformational change of the C-terminal region of the LOV2 domain occurs, and characterizing this change is important for understanding biological function, that is, kinase activation...
April 19, 2017: Journal of Physical Chemistry. B
https://www.readbyqxmd.com/read/28383569/gating-mechanisms-underlying-deactivation-slowing-by-two-kcnq1-atrial-fibrillation-mutations
#18
Gary Peng, Rene Barro-Soria, Kevin J Sampson, H Peter Larsson, Robert S Kass
KCNQ1 is a voltage-gated potassium channel that is modulated by the beta-subunit KCNE1 to generate IKs, the slow delayed rectifier current, which plays a critical role in repolarizing the cardiac action potential. Two KCNQ1 gain-of-function mutations that cause a genetic form of atrial fibrillation, S140G and V141M, drastically slow IKs deactivation. However, the underlying gating alterations remain unknown. Voltage clamp fluorometry (VCF) allows simultaneous measurement of voltage sensor movement and current through the channel pore...
April 6, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28378799/non-photonic-sensing-of-membrane-delimited-reactive-species-with-a-na-channel-protein-containing-selenocysteine
#19
Navin K Ojha, Enrico Leipold, Roland Schönherr, Toshinori Hoshi, Stefan H Heinemann
Photonic experiments are of key importance in life sciences but light-induced side effects are serious confounding factors. Here we introduce roNaV2, an engineered voltage-gated Na(+) channel harboring a selenocysteine in its inactivation motif, as a non-photonic, sensitive, gateable, and reversible sensor for membrane-delimited reactive species. roNaV2 allows for the assessment of chemical modification induced in fluorescence microscopy settings with high sensitivity and time resolution and it demonstrates the usefulness of ion channels as highly sensitive reporters of membrane processes...
April 5, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28373676/x-ray-induced-electrostatic-graphene-doping-via-defect-charging-in-gate-dielectric
#20
Pavel Procházka, David Mareček, Zuzana Lišková, Jan Čechal, Tomáš Šikola
Graphene field effect transistors are becoming an integral part of advanced devices. Hence, the advanced strategies for both characterization and tuning of graphene properties are required. Here we show that the X-ray irradiation at the zero applied gate voltage causes very strong negative doping of graphene, which is explained by X-ray radiation induced charging of defects in the gate dielectric. The induced charge can be neutralized and compensated if the graphene device is irradiated by X-rays at a negative gate voltage...
April 3, 2017: Scientific Reports
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