bluuebunny/crossref_metadata_2025_split huggingface dataset:
Visualisierung proteinspezifischer Glycosylierung in lebenden Zellen
Authors: Doll Franziska , Buntz Annette , Späte Anne‐Katrin , Schart Verena F. , Timper Alexander , Schrimpf Waldemar , Hauck Christof R. , Zumbusch Andreas , Wittmann Valentin 
Published: January 2016

AbstractDie Glycosylierung von Proteinen ist eine weit verbreitete posttranslationale Modifikation, die an der Regulation vieler Proteinfunktionen beteiligt ist. Um die biologischen Funktionen dieser Modifikation zu verstehen, wäre die Visualisierung des Glycosylierungszustandes spezifischer Proteine in lebenden Zellen von entscheidender Bedeutung. Bisher wurde dies noch nicht erreicht. Hier zeigen wir die Detektion proteinspezifischer Glycosylierung der intrazellulären Proteine OGT, Foxo1, p53 und Akt1 in lebenden Zellen. Unser breit anwendbarer Ansatz beruht auf der Fluoreszenzmarkierung intrazellulärer, metabolisch eingebauter Kohlenhydrate durch Diels‐Alder‐Chemie. Die gewählten Proteine sind mit grün fluoreszierendem Protein (EGFP) markiert. Fluoreszenzlebenszeitmikroskopie (FLIM) gestattet die Detektion von Förster‐Resonanzenergietransfer (FRET) zwischen EGFP und dem am Glycan gebundenen Fluorophor mit hohem Kontrast selbst in Gegenwart des großen Überschusses an Akzeptorfluorophor.
Optimal Synthetic Glycosylation of a Therapeutic Antibody
Authors: Parsons Thomas B. , Struwe Weston B. , Gault Joseph , Yamamoto Keisuke , Taylor Thomas A. , Raj Ritu , Wals Kim , Mohammed Shabaz , Robinson Carol V. , Benesch Justin L. P. , Davis Benjamin G. 
Published: January 2016

AbstractGlycosylation patterns in antibodies critically determine biological and physical properties but their precise control is a significant challenge in biology and biotechnology. We describe herein the optimization of an endoglycosidase‐catalyzed glycosylation of the best‐selling biotherapeutic Herceptin, an anti‐HER2 antibody. Precise MS analysis of the intact four‐chain Ab heteromultimer reveals nonspecific, non‐enzymatic reactions (glycation), which are not detected under standard denaturing conditions. This competing reaction, which has hitherto been underestimated as a source of side products, can now be minimized. Optimization allowed access to the purest natural form of Herceptin to date (≥90 %). Moreover, through the use of a small library of sugars containing non‐natural functional groups, Ab variants containing defined numbers of selectively addressable chemical tags (reaction handles at Sia C1) in specific positions (for attachment of cargo molecules or “glycorandomization”) were readily generated.
A Mononuclear CoII Coordination Complex Locked in a Confined Space and Acting as an Electrochemical Water‐Oxidation Catalyst: A “Ship‐in‐a‐Bottle” Approach
Authors: Manna Paulami , Debgupta Joyashish , Bose Suranjana , Das Samar K. 
Published: January 2016

AbstractPreparing efficient and robust water oxidation catalyst (WOC) with inexpensive materials remains a crucial challenge in artificial photosynthesis and for renewable energy. Existing heterogeneous WOCs are mostly metal oxides/hydroxides immobilized on solid supports. Herein we report a newly synthesized and structurally characterized metal–organic hybrid compound [{Co3(μ3‐OH)(BTB)2(dpe)2} {Co(H2O)4(DMF)2}0.5]n⋅n H2O (Co‐WOC‐1) as an effective and stable water‐oxidation electrocatalyst in an alkaline medium. In the crystal structure of Co‐WOC‐1, a mononuclear CoII complex {Co(H2O)4(DMF)2}2+ is encapsulated in the void space of a 3D framework structure and this translationally rigid complex cation is responsible for a remarkable electrocatalytic WO activity, with a catalytic turnover frequency (TOF) of 0.05 s−1 at an overpotential of 390 mV (vs. NHE) in 0.1 m KOH along with prolonged stability. This host–guest system can be described as a “ship‐in‐a‐bottle”, and is a new class of heterogeneous WOC.
Use of a “Catalytic” Cosolvent, N,N‐Dimethyl Octanamide, Allows the Flow Synthesis of Imatinib with no Solvent Switch
Authors: Yang Jeffrey C. , Niu Dawen , Karsten Bram P. , Lima Fabio , Buchwald Stephen L. 
Published: January 2016

AbstractA general, efficient method for C−N cross‐coupling has been developed using N,N‐dimethyloctanamide as a catalytic cosolvent for biphasic continuous‐flow applications. The described method was used to generate a variety of biarylamines and was integrated into a two‐step sequence which converted phenols into biarylamines via either triflates or tosylates. Additionally, the method was applied to a three‐step synthesis of imatinib, the API of Gleevec, in good yield without the need of solvent switches.
Stereoselective Synthesis of Polycycles Containing an Aziridine Group: Intramolecular aza‐Diels–Alder Reactions of Unactivated 2H‐Azirines with Unactivated Dienes
Authors: Xu Hua‐Dong , Zhou Hao , Pan Ying‐Peng , Ren Xin‐Tao , Wu Hao , Han Mei , Han Run‐Ze , Shen Mei‐Hua 
Published: January 2016

AbstractVinyl azide with a pendent diene can undergo thermal decomposition to a related azirine intermediate, which was used immediately in an intramolecular aza‐Diels–Alder reaction to furnish an aziridine‐containing trans‐fused tricyclic core structure with excellent stereoselectivity. The method provides a facile entry to complex polycyclic alkaliods which can be further elaborated by ring‐opening reactions and ring expansion of the aziridine moiety, as well as by dihydroxylation of the alkene group.
Total Synthesis of (±)‐Alstoscholarisine A
Authors: Bihelovic Filip , Ferjancic Zorana 
Published: January 2016

AbstractThe first total synthesis of the neuroactive indole alkaloid (±)‐alstoscholarisine A is reported. The key step of the concise synthesis is an efficient domino sequence that was used to assemble the 2,8‐diazabicyclo[3.3.1]nonane core through the formation of two C−N bonds and one C−C bond in a single step.
Strong‐Coupled Cobalt Borate Nanosheets/Graphene Hybrid as Electrocatalyst for Water Oxidation Under Both Alkaline and Neutral Conditions
Authors: Chen Pengzuo , Xu Kun , Zhou Tianpei , Tong Yun , Wu Junchi , Cheng Han , Lu Xiuli , Ding Hui , Wu Changzheng , Xie Yi 
Published: January 2016

AbstractDeveloping highly active catalysts for the oxygen evolution reaction (OER) is of paramount importance for designing various renewable energy storage and conversion devices. Herein, we report the synthesis of a category of Co‐Pi analogue, namely cobalt‐based borate (Co‐Bi) ultrathin nanosheets/graphene hybrid by a room‐temperature synthesis approach. Benefiting from the high surface active sites exposure yield, enhanced electron transfer capacity, and strong synergetic coupled effect, this Co‐Bi NS/G hybrid shows high catalytic activity with current density of 10 mA cm−2 at overpotential of 290 mV and Tafel slope of 53 mV dec−1 in alkaline medium. Moreover, Co‐Bi NS/G electrocatalysts also exhibit promising performance under neutral conditions, with a low onset potential of 235 mV and high current density of 14.4 mA cm−2 at 1.8 V, which is the best OER performance among well‐developed Co‐based OER electrocatalysts to date. Our finding paves a way to develop highly active OER electrocatalysts.
Visualization of Protein‐Specific Glycosylation inside Living Cells
Authors: Doll Franziska , Buntz Annette , Späte Anne‐Katrin , Schart Verena F. , Timper Alexander , Schrimpf Waldemar , Hauck Christof R. , Zumbusch Andreas , Wittmann Valentin 
Published: January 2016

AbstractProtein glycosylation is a ubiquitous post‐translational modification that is involved in the regulation of many aspects of protein function. In order to uncover the biological roles of this modification, imaging the glycosylation state of specific proteins within living cells would be of fundamental importance. To date, however, this has not been achieved. Herein, we demonstrate protein‐specific detection of the glycosylation of the intracellular proteins OGT, Foxo1, p53, and Akt1 in living cells. Our generally applicable approach relies on Diels–Alder chemistry to fluorescently label intracellular carbohydrates through metabolic engineering. The target proteins are tagged with enhanced green fluorescent protein (EGFP). Förster resonance energy transfer (FRET) between the EGFP and the glycan‐anchored fluorophore is detected with high contrast even in presence of a large excess of acceptor fluorophores by fluorescence lifetime imaging microscopy (FLIM).
Small‐Molecule PROTACS: New Approaches to Protein Degradation
Authors: Toure Momar , Crews Craig M. 
Published: January 2016

AbstractThe current inhibitor‐based approach to therapeutics has inherent limitations owing to its occupancy‐based model: 1) there is a need to maintain high systemic exposure to ensure sufficient in vivo inhibition, 2) high in vivo concentrations bring potential for off‐target side effects, and 3) there is a need to bind to an active site, thus limiting the drug target space. As an alternative, induced protein degradation lacks these limitations. Based on an event‐driven model, this approach offers a novel catalytic mechanism to irreversibly inhibit protein function by targeting protein destruction through recruitment to the cellular quality control machinery. Prior protein degrading strategies have lacked therapeutic potential. However, recent reports of small‐molecule‐based proteolysis‐targeting chimeras (PROTACs) have demonstrated that this technology can effectively decrease the cellular levels of several protein classes.
Reactive Oxygen Species Play an Important Role in the Bactericidal Activity of Quinolone Antibiotics
Authors: Kottur Jithesh , Nair Deepak T. 
Published: January 2016

AbstractRecent studies posit that reactive oxygen species (ROS) contribute to the cell lethality of bactericidal antibiotics. However, this conjecture has been challenged and remains controversial. To resolve this controversy, we adopted a strategy that involves DNA polymerase IV (PolIV). The nucleotide pool of the cell gets oxidized by ROS and PolIV incorporates the damaged nucleotides (especially 8oxodGTP) into the genome, which results in death of the bacteria. By using a combination of structural and biochemical tools coupled with growth assays, it was shown that selective perturbation of the 8oxodGTP incorporation activity of PolIV results in considerable enhancement of the survival of bacteria in the presence of the norfloxacin antibiotic. Our studies therefore indicate that ROS induced in bacteria by the presence of antibiotics in the environment contribute significantly to cell lethality.
Direct Observation of Self‐Organized Water‐Containing Structures in the Liquid Phase and Their Influence on 5‐(Hydroxymethyl)furfural Formation in Ionic Liquids
Authors: Kashin Alexey S. , Galkin Konstantin I. , Khokhlova Elena A. , Ananikov Valentine P. 
Published: January 2016

AbstractWater‐containing organic solutions are widespread reaction media in organic synthesis and catalysis. This type of multicomponent liquid system has a number of unique properties because of the tendency for water to self‐organize in mixtures with other liquids. The characterization of these water domains is a challenging task because of their soft and dynamic nature. In the present study, the morphology and dynamics of micrometer‐ and nanometer‐scale water‐containing compartments in ionic liquids were directly observed by electron microscopy. A variety of morphologies, including isolated droplets, dense structures, aggregates, and 2D meshworks, have been experimentally detected and studied. Using the developed method, the impact of water on the acid‐catalyzed biomass conversion reaction was studied at the microscopic level. The process that produced nanostructured domains in solution led to better yields and higher selectivities compared with reactions involving the bulk system.
Single‐Cell Mass Spectrometry for Discovery Proteomics: Quantifying Translational Cell Heterogeneity in the 16‐Cell Frog (Xenopus) Embryo
Authors: Lombard‐Banek Camille , Moody Sally A. , Nemes Peter 
Published: January 2016

AbstractWe advance mass spectrometry from a cell population‐averaging tool to one capable of quantifying the expression of diverse proteins in single embryonic cells. Our instrument combines capillary electrophoresis (CE), electrospray ionization, and a tribrid ultrahigh‐resolution mass spectrometer (HRMS) to enable untargeted (discovery) proteomics with ca. 25 amol lower limit of detection. CE‐μESI‐HRMS enabled the identification of 500–800 nonredundant protein groups by measuring 20 ng, or <0.2% of the total protein content in single blastomeres that were isolated from the 16‐cell frog (Xenopus laevis) embryo, amounting to a total of 1709 protein groups identified between n=3 biological replicates. By quantifying ≈150 nonredundant protein groups between all blastomeres and replicate measurements, we found significant translational cell heterogeneity along multiple axes of the embryo at this very early stage of development when the transcriptional program of the embryo has yet to begin.
Catalyst‐Controlled Switch in Chemo‐ and Diastereoselectivities: Annulations of Morita–Baylis–Hillman Carbonates from Isatins
Authors: Zhan Gu , Shi Ming‐Lin , He Qing , Lin Wei‐Jia , Ouyang Qin , Du Wei , Chen Ying‐Chun 
Published: January 2016

AbstractRegulating both the chemo‐ and diastereoselectivity, divergently, of a reaction is highly attractive but extremely challenging. Presented herein is a catalyst‐controlled switch in the chemo‐ and diastereodivergent annulation reactions of Morita–Baylis–Hillman carbonates, derived from isatins and 2‐alkylidene‐1H‐indene‐1,3(2H)‐diones, in exclusive α‐regioselectivity. α‐Isocupreine efficiently catalyzed [2+1] reactions to access cyclopropane derivatives, and the diastereodivergent [3+2] annulations were accomplished by employing either a chiral phosphine or a DMAP‐type molecule. All reactions exhibited excellent chemoselectivities, and good to remarkable stereoselectivities were furnished, thus leading to a collection of compounds with skeletal and stereogenic diversity. Moreover, DFT computational calculations elucidated the catalyst‐based switch in mechanism.
Electroresponsive Structurally Colored Materials: A Combination of Structural and Electrochromic Effects
Authors: Kuno Tomoya , Matsumura Yoshimasa , Nakabayashi Koji , Atobe Mahito 
Published: January 2016

AbstractElectroresponsive structurally colored materials composed of ordered arrays of polyaniline@poly(methyl methacrylate) (PANI@PMMA) core–shell nanoparticles have been successfully prepared. The core–shell nanoparticles were synthesized by deposition of PANI shells on the surfaces of the PMMA cores by the oxidative polymerization of anilinium chloride. Ordered arrays were then fabricated by using the fluidic cell method. Because the ordered arrays and the PANI shells generate structural and electrochromic colors, respectively, these core–shell colloidal crystals exhibited colors resulting from the combined effects of these materials. The crystal colors depended greatly on the size of PANI@PMMA particles and could also be varied by the application of a voltage. The electrochromic colors of these arrays were found to be quite different from those exhibited by pure PANI films prepared by electrochemical oxidation.
Synthesis of a perfluorooctanoic acid molecularly imprinted polymer for the selective removal of perfluorooctanoic acid in an aqueous environment
Authors: Cao Fengmei , Wang Lei , Ren Xinhao , Sun Hongwen 
Published: January 2016

ABSTRACTPerfluorooctanoic acid (PFOA) contamination in the environment is a global problem. The aqueous phase is the main medium for PFOA because of its moderate solubility. Adsorption is a feasible way to remove PFOA because of its chemical and biological stability. In this study, a new type of molecularly imprinted polymer (MIP) for the selective adsorption of PFOA in aqueous solutions was synthesized by the precipitation polymerization method with PFOA as the template molecule after optimization. The adsorption kinetics and isotherms of the MIP adsorbent toward PFOA were studied, and the effects of the pH and cations on the adsorption were investigated with batch experiments. The results show that acrylamide (AAM) was the best functional monomer, and the optimal molar ratio of PFOA to AAM to ethylene glycol dimethacrylate (crosslinker) was 1:6:25. The optimized MIP adsorbent had a high affinity for PFOA, and the uptake percentage by the MIP adsorbent was 1.3–2.5 times that of the nonimprinted polymer (NIP) when PFOA existed alone. A maximum PFOA sorption capacity of 5.45 mg/g based on the Langmuir isotherm model was achieved with the MIP adsorbent. The MIP adsorbent exhibited a high selectivity for PFOA over competitive compounds (other perfluorinated alkyl carboxylic and sulfonic acids), whereas the NIP did not. Approximately 90% of the PFOA in the mixture was removed by the MIP adsorbent; this was 18 times that of the NIP. Moreover, the regenerability of the MIP adsorbent was confirmed in five sequential adsorption–desorption cycles without a significant reduction in the PFOA uptake. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43192.
Tissue Levels of Stefin A and Stefin B in Hepatocellular Carcinoma
Authors: Lin Yang‐Yuan , Chen Zhi‐Wei , Lin Zhi‐Ping , Lin Li‐Bin , Yang Xue‐Ming , Xu Li‐Yan , Xie Qun 
Published: January 2016

ABSTRACT Stefins have been reported to be associated with the progression and metastasis of various malignant tumors. However, the expressions of stefins in hepatocellular carcinoma (HCC) have not been well‐defined. In this study, the protein levels of stefin A and stefin B were assessed by immunohistochemical staining, and the mRNA levels were quantified by real‐time polymerase chain reaction in 85 primary HCC tissues, 85 surrounding non‐cancerous tissues, and 9 normal hepatic tissues. The immunohistochemical staining of cathepsin B and cathepsin D, and the ratio of cathepsins to stefins were assessed. The mRNA expressions of stefin A and stefin B in HCC tissues were significantly higher than surrounding noncancerous tissues and normal hepatic tissues, respectively. A significant positive relationship of stefin A and stefin B was found with node metastasis, tumor size, and Edmondson grade for HCC. Univariate and multivariate analyses revealed that Edmondson grade and stefin B expression were independent factors associated with the risk of lymph node metastasis in HCC. The ratios of cathepsin B to stefin A, cathepsin D to stefin A, cathepsin B to stefin B and cathepsin D to stefin B of the HCC group were significantly higher than that of the surrounding noncancerous group. A significant positive correlation between the ratio of cathepsins to stefins (cathepsin B/stefin A, cathepsin B/stefin B and cathepsin D/stefin B) and node metastasis was demonstrated. We concluded that high expressions of stefin A and stefin B may be an important factor contributing to the development and metastasis of HCC. Anat Rec, 299:428–438, 2016. © 2016 Wiley Periodicals, Inc.
Free‐Standing Membranes to Study the Optical Properties of Anodic TiO2 Nanotube Layers
Authors: Cha Gihoon , Schmuki Patrik , Altomare Marco 
Published: January 2016

AbstractIn the present work we investigate various optical properties (such as light absorption and reflectance) of anodic TiO2 nanotube layers directly transferred as self‐standing membranes onto quartz substrates. This allows investigation in a transmission geometry which provides significantly more reliable data than measurements on the metallic Ti substrate. Light transmission and reflectance measurements were carried out for layers of thickness varying from 1.8 to 50 μm, and the layers were investigated in their amorphous and crystalline forms. A series of wavelength‐dependent light attenuation coefficients are extrapolated and found to match the photocurrent versus irradiation wavelength behavior. A feature specific to anodic nanotubes is that their intrinsic carbon contamination content causes a proportional sub‐bandgap response. Overall, the extracted data provide a valuable basis and understanding for the design of photo‐electrochemical devices based on TiO2 nanotubes.
Optimization and modeling for the synthesis of sterol esters from deodorizer distillate by lipase‐catalyzed esterification
Authors: Zhang Xinyu , Yu Jiang , Zeng Aiwu 
Published: January 2016

AbstractIn this paper, cotton seed oil deodorizer distillate (CSODD), was recovered to obtain fatty acid sterol ester (FASE), which is one of the biological activated substances added as human therapeutic to lower cholesterol. Esterification reactions were carried out using Candida rugosa lipase as a catalyst, and the conversion of phytosterol was optimized using response surface methodology. The highest conversion (90.8 ± 0.4%) was reached at 0.84 wt% enzyme load, 1:25 solvent/CSODD mass ratio, and 44.2 °C after 12 H reaction. A kinetic model based on the reaction rate equation was developed to describe the reaction process. The activation energy of the reaction was calculated to be 56.9 kJ/mol and the derived kinetic parameters provided indispensable basics for further study. The optimization and kinetic research of synthesizing FASE from deodorizer distillate provided necessary information for the industrial applications in the near future. Experimental results showed that the proposed process is a promising alternative to recycle sterol esters from vegetable oil deodorizer distillates in a mild, efficient, and environmental friendly method.
Optimization of a cytochrome P450 oxidation system for enhancing protopanaxadiol production in Saccharomyces cerevisiae
Authors: Zhao Fanglong , Bai Peng , Liu Ting , Li Dashuai , Zhang Xiangmei , Lu Wenyu , Yuan Yingjin 
Published: January 2016

ABSTRACTGinsenosides, the major bioactive components of Panax ginseng, are regarded as promising high‐value pharmaceutical compounds. In ginseng, ginsenosides are produced from their precursor protopanaxadiol. Recently, an artificial biosynthetic pathway of protopanaxadiol was built in Saccharomyces cerevisiae by introducing a P. ginseng dammarenediol‐II synthase, a P. ginseng cytochrome P450‐type protopanaxadiol synthase (PPDS), and a Arabidopsis thaliana NADPH‐cytochrome P450 reductase (ATR1). In this engineered yeast strain, however, the low metabolic flux through PPDS resulted in a low productivity of protopanaxadiol. Moreover, health of the yeast cells was significantly affected by reactive oxygen species released by the pool coupling between PPDS and ATR1. To overcome the obstacles in protopanaxadiol production, PPDS was modified through transmembrane domain truncation and self‐sufficient PPDS–ATR1 fusion construction in this study. The fusion enzymes conferred approximately 4.5‐fold increase in catalytic activity, and 71.1% increase in protopanaxadiol production compared with PPDS and ATR1 co‐expression. Our in vivo experiment indicated that the engineered yeast carrying fusion protein effectively converted 96.8% of dammarenediol‐II into protopanaxadiol. Protopanaxadiol production in a 5 L bioreactor in fed‐batch fermentation reached 1436.6 mg/L. Our study not only improved protopanaxadiol production in yeast, but also provided a generic method to improve activities of plant cytochrome P450 monooxygenases. This method is promising to be applied to other P450 systems in yeast. Biotechnol. Bioeng. 2016;113: 1787–1795. © 2016 Wiley Periodicals, Inc.