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https://www.readbyqxmd.com/read/28922749/unraveling-additional-o-methylation-steps-in-benzylisoquinoline-alkaloid-biosynthesis-in-california-poppy-eschscholzia-californica
#1
Ratmoyo Purwanto, Kentaro Hori, Yasuyuki Yamada, Fumihiko Sato
California poppy (Eschscholzia californica), a member of the Papaveraceae family, produces many biologically active benzylisoquinoline alkaloids (BIAs), such as sanguinarine, macarpine and chelerythrine. Sanguinarine biosynthesis has been elucidated at the molecular level, and its biosynthetic genes have been isolated and used in synthetic biology approaches to produce BIAs in vitro. However, several genes involved in the biosynthesis of macarpine and chelerythrine have not yet been characterized. In this study, we report the isolation and characterization of a novel O-methyltransferase (OMT) involved in the biosynthesis of partially characterized BIAs, especially chelerythrine...
September 1, 2017: Plant & Cell Physiology
https://www.readbyqxmd.com/read/28922313/lateral-perturbation-induced-stepping-strategies-and-predictors-in-persons-poststroke
#2
Vicki L Gray, Chieh-Ling Yang, Sandy McCombe Waller, Mark W Rogers
BACKGROUND AND PURPOSE: Falls commonly occur as weight is transferred laterally, and impaired reactive stepping responses are associated with falls after stroke. The purpose of this study was to examine differences in and the determinants of mediolateral (M-L) protective stepping strategies when pulled off balance toward the paretic and nonparetic sides. METHODS: Eighteen individuals more than 6 months poststroke were pulled in the M-L direction by a lateral waist-pull perturbation system...
October 2017: Journal of Neurologic Physical Therapy: JNPT
https://www.readbyqxmd.com/read/28921959/quantification-and-theoretical-analysis-of-the-electrophilicities-of-michael-acceptors
#3
Dominik S Allgäuer, Harish Jangra, Haruyasu Asahara, Zhen Li, Quan Chen, Hendrik Zipse, Armin R Ofial, Herbert Mayr
In order to quantify the electrophilic reactivities of common Michael acceptors, we measured the kinetics of the reactions of monoacceptor-substituted ethylenes (H2C═CH-Acc, 1) and styrenes (PhCH═CH-Acc, 2) with pyridinium ylides 3, sulfonium ylide 4, and sulfonyl-substituted chloromethyl anion 5. Substitution of the 57 measured second-order rate constants (log k) and the previously reported nucleophile-specific parameters N and sN for 3-5 into the correlation log k = sN(E + N) allowed us to calculate 15 new empirical electrophilicity parameters E for Michael acceptors 1 and 2...
September 18, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28921442/preparation-of-immunoliposomes-by-direct-coupling-of-antibodies-based-on-a-thioether-bond
#4
Raquel Petrilli, Josimar O Eloy, Robert J Lee, Renata F V Lopez
Drug delivery is of paramount importance, since the drug needs to be delivered to a specific site, in adequate concentration, avoiding degradation in order to provide therapeutic efficacy. Different nanocarriers have been used over the years for this purpose and liposomes are well-established systems due to the high biocompatibility and the possibility to vehiculate both hydrophilic and lipophilic drugs. In order to circumvent the rapid clearance by the reticuloendothelial system and to avoid the healthy cells exposure to the drug, long circulating liposomes containing polyethyleneglycol (PEG) and functionalized liposomes for targeted delivery have been developed...
2018: Methods in Molecular Biology
https://www.readbyqxmd.com/read/28914473/ethers-on-si-001-a-prime-example-for-the-common-ground-between-surface-science-and-molecular-organic-chemistry
#5
Lisa Pecher, Slimane Laref, Marc Raupach, Ralf Ewald Tonner
Using computational chemistry, we show that the adsorption of ether molecules on Si(001) under ultra-high vacuum conditions can be understood with textbook organic chemistry. The two-step reaction mechanism of (1) dative bond formation between the ether oxygen and a Lewis acidic surface atom and (2) a nucleophilic attack of a nearby Lewis basic surface atom is analysed in detail and found to mirror the acid-catalysed ether cleavage in solution. The O-Si dative bond is found to be the strongest of its kind and reactivity from this state defies the Bell-Evans-Polanyi principle...
September 15, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28914306/enhanced-intermediate-temperature-co2-splitting-using-nonstoichiometric-ceria-and-ceria-zirconia
#6
Zhenlong Zhao, Mruthunjaya Uddi, Nikolai Tsvetkov, Bilge Yildiz, Ahmed F Ghoniem
CO2 splitting via thermo-chemical or reactive redox has emerged as a novel and promising carbon-neutral energy solution. Its performance depends critically on the properties of the oxygen carriers (OC). Ceria is recognized as one of the most promising OC candidates, because of its fast chemistry, high ionic diffusivity, and large oxygen storage capacity. The fundamental surface ion-incorporation pathways, along with the role of surface defects and the adsorbates remain largely unknown. This study presents a detailed kinetics study of CO2 splitting using CeO2 and Ce0...
September 15, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28912168/alternative-polyadenylation-of-prelid1-regulates-mitochondrial-ros-signaling-and-cancer-outcomes
#7
Austin E Gillen, Heather M Brechbuhl, Tomomi M Yamamoto, Enos C Kline, Manoj Pillai, Jay Hesselberth, Peter Kabos
Disruption of post-transcriptional gene regulation is a critical step in oncogenesis that can be difficult to observe using traditional molecular techniques. To overcome this limitation, a modified polyadenylation site sequencing (PAS-seq) protocol was used to generate a genome-wide map of alternative polyadenylation (APA) events in human primary breast tumor specimens and matched normal tissue. This approach identified an APA event in the PRELID1 mRNA that enhances its steady state level and translational efficiency, and is a strong breast cancer subtype-dependent predictor of patient clinical outcomes...
September 14, 2017: Molecular Cancer Research: MCR
https://www.readbyqxmd.com/read/28911864/multiscale-approach-to-the-activation-and-phosphotransfer-mechanism-of-cpxa-histidine-kinase-reveals-a-tight-coupling-between-conformational-and-chemical-steps
#8
Franco Marsico, Osvaldo Burastero, Lucas A Defelipe, Elias Daniel Lopez, Mehrnoosh Arrar, Adrián G Turjanski, Marcelo A Marti
Sensor histidine kinases (SHKs) are an integral component of the molecular machinery that permits bacteria to adapt to widely changing environmental conditions. CpxA, an extensively studied SHK, is a multidomain homodimeric protein with each subunit consisting of a periplasmic sensor domain, a transmembrane domain, a signal-transducing HAMP domain, a dimerization and histidine phospho-acceptor sub-domain (DHp) and a catalytic and ATP-binding subdomain (CA). The key activation event involves the rearrangement of the HAMP-DHp helical core and translation of the CA towards the acceptor histidine, which presumably results in a autokinase-competent complex...
September 11, 2017: Biochemical and Biophysical Research Communications
https://www.readbyqxmd.com/read/28905812/carbon-fiber-on-polyimide-ultra-microelectrodes
#9
Wintrop F Gillis, Charles A Lissandrello, Jun Shen, Ben W Pearre, Alket Mertiri, Felix Deku, Stuart Cogan, Bradley J Holinski, Daniel J Chew, Alice E White, Timothy M Otchy, Timothy Gardner
OBJECTIVE: Most preparations for making neural recordings degrade over time and eventually fail due to insertion trauma and reactive tissue response. The magnitudes of these responses are thought to be related to the electrode size (specifically, the cross-sectional area), the relative stiffness of the electrode, and the degree of tissue tolerance for the material. Flexible carbon fiber ultra-microelectrodes have a much smaller cross-section than traditional electrodes and low tissue reactivity, and thus may enable improved longevity of neural recordings in the central and peripheral nervous systems...
September 14, 2017: Journal of Neural Engineering
https://www.readbyqxmd.com/read/28902992/removal-of-antibiotic-florfenicol-by-sulfide-modi%C3%AF-ed-nanoscale-zero-valent-iron
#10
Zhen Cao, Xue Liu, Jiang Xu, Jing Zhang, Yi Yang, Jun Liang Zhou, Xinhua Xu, Gregory V Lowry
Florfenicol (FF, C12H14Cl2FNO4S), an emerging halogenated organic contaminant of concern was effectively degraded in water by sulfidized nanoscale zero-valent iron (S-nZVI). Sulfidized nZVI (62.5 m2 g-1) that was prepared using a one-step method resulted in small Fe0/Fe-sulfide particles that were more stable against aggregation than unsulfidized nZVI (10.2 m2 g-1). No obvious removal of FF was observed by unsulfidized nZVI. S-nZVI degraded FF, having a surface area normalized reaction rate constant of 3.1×10-4 L m-2 min-1...
September 13, 2017: Environmental Science & Technology
https://www.readbyqxmd.com/read/28901757/metal-free-borylation-of-heteroarenes-using-ambiphilic-aminoboranes-on-the-importance-of-sterics-in-frustrated-lewis-pair-c-h-bond-activation
#11
Julien Légaré Lavergne, Arumugam Jayaraman, Luis C Misal-Castro, Etienne Rochette, Frédéric-Georges Fontaine
Two novel frustrated Lewis pair (FLP) aminoboranes, (1-Pip-2-BH2-C6H4)2 (2; Pip = piperidyl) and (1-NEt2-2-BH2-C6H4)2 (3; NEt2 = diethylamino), were synthesized and their structural features were elucidated both in solution and in the solid state. The reactivity of these species for the borylation of heteroarenes was investigated and compared to previously reported (1-TMP-2-BH2-C6H4)2 (1; TMP = tetramethylpiperidyl) and (1-NMe2-2-BH2-C6H4)2 (4; NMe2 = dimethylamino). It was shown that 2 and 3 are more active catalysts for the borylation of heteroarenes than the bulkier analogue 1...
September 13, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28898786/catalytic-activation-of-o2-molecule-by-transition-metal-atoms-deposited-on-the-outer-surface-of-bn-nanocluster
#12
Akbar Omidvar
The activation of the O2 molecule and yielding two separated O atoms is an essential step for the oxygen reduction reaction processes. Dissociation of the strong bond in the O2 often involves large activation barriers on metal particles used as catalysts. Here, the catalytic activity for the O2 dissociation of the transition metals (Fe, Co, Ni, Cu, Rh, Pd, Ag, Ir, Pt, and Au) deposited on the BN nanocluster have been studied theoretically using density functional theory. The following outcomes can be derived from our calculations: (1) The strong interaction between the Fe and Ni metal atoms and boron atom in BN nanocluster suggests that these transition metals deposited on BN nanocluster should be stable under high temperatures...
September 4, 2017: Journal of Molecular Graphics & Modelling
https://www.readbyqxmd.com/read/28898063/catalytic-c-sp3-h-alkylation-via-an-iron-carbene-intermediate
#13
Jennifer R Griffin, Chloe I Wendell, Jacob A Garwin, M Christina White
The catalytic transformation of a C(sp3)-H bond to a C(sp3)-C bond via an iron carbene intermediate represents a long-standing challenge. Despite the success of enzymatic and small molecule iron catalysts mediating challenging C(sp3)-H oxidations and aminations via high-valent iron oxos and nitrenes, C(sp3)-H alkylations via isoelectronic iron carbene intermediates have thus far been unsuccessful. Iron carbenes have been inert, or shown to favor olefin cyclopropanation and heteroatom-hydrogen insertion. Herein we report an iron phthalocyanine-catalyzed alkylation of allylic and benzylic C(sp3)-H bonds...
September 12, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28894619/immunological-reactivity-using-monoclonal-and-polyclonal-antibodies-of-autoimmune-thyroid-target-sites-with-dietary-proteins
#14
Datis Kharrazian, Martha Herbert, Aristo Vojdani
Many hypothyroid and autoimmune thyroid patients experience reactions with specific foods. Additionally, food interactions may play a role in a subset of individuals who have difficulty finding a suitable thyroid hormone dosage. Our study was designed to investigate the potential role of dietary protein immune reactivity with thyroid hormones and thyroid axis target sites. We identified immune reactivity between dietary proteins and target sites on the thyroid axis that includes thyroid hormones, thyroid receptors, enzymes, and transport proteins...
2017: Journal of Thyroid Research
https://www.readbyqxmd.com/read/28893984/nanoswitch-linked-immunosorbent-assay-nlisa-for-fast-sensitive-and-specific-protein-detection
#15
Clinton H Hansen, Darren Yang, Mounir A Koussa, Wesley P Wong
Protein detection and quantification play critical roles in both basic research and clinical practice. Current detection platforms range from the widely used ELISA to more sophisticated, and more expensive, approaches such as digital ELISA. Despite advances, there remains a need for a method that combines the simplicity and cost-effectiveness of ELISA with the sensitivity and speed of modern approaches in a format suitable for both laboratory and rapid, point-of-care applications. Building on recent developments in DNA structural nanotechnology, we introduce the nanoswitch-linked immunosorbent assay (NLISA), a detection platform based on easily constructed DNA nanodevices that change conformation upon binding to a target protein with the results read out by gel electrophoresis...
September 11, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28892873/combination-of-pcr-and-dual-nanoparticles-for-detection-of-plasmodium-falciparum
#16
Tienrat Tangchaikeeree, Duangporn Polpanich, Abderrazzak Bentaher, Abdoullatif Baraket, Abdelhamid Errachid, Geraldine Agusti, Abdelhamid Elaissari, Kulachart Jangpatarapongsa
Highly reactive particle-based DNA amplification was developed for the detection of the Pfg377 gene from P. falciparum gametocytes using functional magnetic latex particles (MLPs) and quantum dots encapsulated polymer particles (QDs-PPs). Firstly, MLPs were prepared from the precipitation of iron oxide, polymerization using initiator, and adsorption of aminodextran (AMD) so as to provide amino-functionalized MLPs. Furthermore, amino-containing polymer particles (PPs) were prepared by emulsifier-free polymerization and encapsulated with fluorescent quantum dots (QDs) for use as a signaling support...
September 2, 2017: Colloids and Surfaces. B, Biointerfaces
https://www.readbyqxmd.com/read/28892493/control-of-multidimensional-systems-on-complex-network
#17
Giulia Cencetti, Franco Bagnoli, Giorgio Battistelli, Luigi Chisci, Duccio Fanelli
Multidimensional systems coupled via complex networks are widespread in nature and thus frequently invoked for a large plethora of interesting applications. From ecology to physics, individual entities in mutual interactions are grouped in families, homogeneous in kind. These latter interact selectively, through a sequence of self-consistently regulated steps, whose deeply rooted architecture is stored in the assigned matrix of connections. The asymptotic equilibrium eventually attained by the system, and its associated stability, can be assessed by employing standard nonlinear dynamics tools...
2017: PloS One
https://www.readbyqxmd.com/read/28890176/a-%C3%AE-subunit-point-mutation-in-chlamydomonas-reinhardtii-chloroplast-f1fo-atp-synthase-confers-tolerance-to-reactive-oxygen-species
#18
Felix Buchert, Benjamin Bailleul, Toru Hisabori
The chloroplast F1Fo-ATP synthase (CF1Fo) drives ATP synthesis and the reverse reaction of ATP hydrolysis. The enzyme evolved in a cellular environment where electron transfer processes and molecular oxygen are abundant, and thiol modulation in the γ-subunit via thioredoxin is important for its ATPase activity regulation. Especially under high light, oxygen can be reduced and forms reactive oxygen species (ROS) which can oxidize CF1Fo among various other biomolecules. Mutation of the conserved ROS targets resulted in a tolerant enzyme, suggesting that ROS might play a regulatory role...
September 7, 2017: Biochimica et Biophysica Acta
https://www.readbyqxmd.com/read/28887385/prior-learning-of-relevant-non-aversive-information-is-a-boundary-condition-for-avoidance-memory-reconsolidation-in-the-rat-hippocampus
#19
Andressa Radiske, Maria Carolina Gonzalez, Sergio Conde-Ocaziones, Anatildes Feitosa, Cristiano A Köhler, Lia R Bevilaqua, Martín Cammarota
Reactivated memories can be modified during reconsolidation, making this process a potential therapeutic target for post-traumatic stress disorder (PTSD), a mental illness characterized by the recurring avoidance of situations that evoke trauma-related fears. However, avoidance memory reconsolidation depends on a set of still loosely defined boundary conditions, limiting the translational value of basic research. In particular, the involvement of the hippocampus in fear-motivated avoidance memory reconsolidation remains controversial...
September 8, 2017: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
https://www.readbyqxmd.com/read/28887171/some-observations-on-solasodine-reactivity
#20
Izabella Jastrzebska, Jacek W Morzycki
This article presents new transformations of solasodine - a representative steroid alkaloid sapogenin from the Solanum family. Oxidation of N,O-diacetylated solasodine with either NaNO2/BF3·Et2O or t-BuONO/BF3·Et2O resulted in partial degradation of the side chain to (20S)-3β-acetoxypregn-5-ene-20,16β-carbolactone (vespertilin acetate). The same starting compound when treated with TMSOTf afforded the corresponding pseudosapogenin after aqueous work-up. However, when the crude reaction mixture was directly subjected to purification on a silica gel column, efficient autoxidation to pregna-5,16-dien-3β-ol-20-one acetate was observed...
September 5, 2017: Steroids
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