73,010 research outputs found
Site-selective enzymatic C‒H amidation for synthesis of diverse lactams
Full text linkPlease note that this work has been retracted by the authors.After publication of the Report “Site-selective enzymatic C‒H amidation for synthesis of diverse lactams” in Science (1, also linked in metadata), efforts to reproduce the work showed that the enzymes do not catalyze the reactions with the activities and selectivities claimed. Careful examination of the first author’s lab notebook then revealed missing contemporaneous entries and raw data for key experiments. The authors therefore have retracted the article from Science and are now retracting the preprint from ChemRxiv. The original paper can be accessed by selecting “Version 1” of the preprint below, or by accessing https://doi.org/10.26434/chemrxiv.7711418.v1. Inha Cho, Zhi-Jun Jia, Frances H. Arnold*Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA 91125, USA.*Corresponding author. Email: [email protected]. I. Cho, Z.-J. Jia, F. H. Arnold, Science 364, 575 (2019). DOI: 10.1126/science.aaw9068*******************************************************************************************Directed evolution of cytochrome P450 enzymes fine-tunes site selectivity of new-to-nature C‒H amidation for modular, sustainable and scalable preparation of enantio-enriched β-, γ- and δ-lactams.</p
The ALMA-PILS survey: First detection of the unsaturated 3-carbon molecules Propenal (CHCHO) and Propylene (CH) towards IRAS 162932422 B
Full text linkAccepted for publication in A&A. 24 pages, 17 figuresInternational audienceComplex organic molecules with three carbon atoms are found in the earliest stages of star formation. In particular, propenal (CHCHO) is a species of interest due to its implication in the formation of more complex species and even biotic molecules. This study aims to search for the presence of CHCHO and other three-carbon species such as propylene (CH) in the hot corino region of the low-mass protostellar binary IRAS 16293--2422 to understand their formation pathways. We use ALMA observations in Band 6 and 7 from various surveys to search for the presence of CH and CHCHO towards the protostar IRAS 16293--2422 B (IRAS 16293B). We report the detection of both CH and CHCHO towards IRAS 16293B, however, no unblended lines were found towards the other component of the binary system, IRAS 16293A. We derive column density upper limits for CH, HCCCHO, n-CHOH, i-CHOH, CO, and cis-HC(O)CHO towards IRAS 16293B. We then use a three-phase chemical model to simulate the formation of these species in a typical prestellar environment followed by its hydrodynamical collapse until the birth of the central protostar. Different formation paths, such as successive hydrogenation and radical-radical additions on grain surfaces, are tested and compared to the observational results. The simulations reproduce the abundances within one order of magnitude from those observed towards IRAS 16293B, with the best agreement found for a rate of cm s for the gas-phase reaction C + O C + CO. Successive hydrogenations of C, HC(O)CHO, and CHOCHO on grain surfaces are a major and crucial formation route of complex organics molecules, whereas both successive hydrogenation pathways and radical-radical addition reactions contribute to the formation of CHCHO
TG, T-cho, H-cho, and cortisol levels in the serum.
No full text<p>CMS group, chronic mild stress group; C group, control group; TG, triglyceride; T-cho, total cholesterol; H-cho, HDL-cholesterol; SD, standard deviation.</p><p>TG, T-cho, H-cho, and cortisol levels in the serum.</p
CHO microRNA engineering is growing up : recent successes and future challenges
Full text linkmicroRNAs with their ability to regulate complex pathways that control cellular behavior and phenotype have been proposed as potential targets for cell engineering in the context of optimization of biopharmaceutical production cell lines, specifically of Chinese Hamster Ovary cells. However, until recently, research was limited by a lack of genomic sequence information on this industrially important cell line. With the publication of the genomic sequence and other relevant data sets for CHO cells since 2011, the doors have been opened for an improved understanding of CHO cell physiology and for the development of the necessary tools for novel engineering strategies. In the present review we discuss both knowledge on the regulatory mechanisms of microRNAs obtained from other biological models and proof of concepts already performed on CHO cells, thus providing an outlook of potential applications of microRNA engineering in production cell lines
Synthesis, Characterization, and Superconducting and Magnetic Properties of Electrochemically Oxidized La2CuO4+δ and La2-xSrxCuO4+δ (0.01 ? x ? 0.33, 0.01 ? δ ? 0.36)
No full textIridium-catalyzed borylation of secondary benzylic C-H bonds directed by a hydrosilane
No full textMost functionalizations of C-H bonds by main-group reagents occur at aryl or methyl groups. We describe a highly regioselective borylation of secondary benzylic C-H bonds catalyzed by an iridium precursor and 3,4,7,8-tetramethyl-1,10-phenanthroline as the ligand. The reaction is directed to the benzylic position by a hydrosilyl substituent. This hydrosilyl directing group is readily deprotected or transformed to other functional groups after the borylation reaction, providing access to a diverse set of secondary benzylboronate esters by C-H borylation chemistry.X115852sciescopu
Mannosylated chitosan nanoparticle–based cytokine gene therapy suppressed cancer growth in BALB/c mice bearing CT-26 carcinoma cells
No full textCancer immunotherapy relies on the ability of the immune system to destroy tumor cells selectively and to elicit a long-lasting memory of such activity. Interleukin-12 (IL-12) is an immunomodulatory cytokine produced primarily by antigen-presenting cells, which play an important role in promoting Th1-type immune response and cell-mediated immunity. To augment the antitumor immune action by in vivo IL-12 gene delivery, mannosylated chitosan (MC) was prepared to induce mannose receptor–mediated endocytosis of IL-12 gene directly into dendritic cells which reside within the tumor. Upon characterization, MC was proven to be suitable for IL-12 gene delivery due to good physicochemical properties and low cytotoxicity. In addition, MC exhibited much enhanced IL-12 gene transfer efficiency to dendritic cells rather than chitosan itself in terms of the induction of murine IL-12 p70 and murine IFN-γ. In animal studies, intratumoral injection of MC/plasmid encoding murine IL-12 complex into BALB/c mice bearing CT-26 carcinoma cells clearly suppressed tumor growth and angiogenesis, and significantly induced cell cycle arrest and apoptosis. Therefore, this study provides a new MC-mediated cytokine gene delivery system for cancer immunotherapy.Ministry of Science and Technology in Korea
(M10414030002-05N1403-00210; T.H. Kim and C.S. Cho) and Nano
Systems Institute-National Core Research Center (H. Jin, H.W. Kim, and
M.H. Cho). H. Jin and H.W. Kim are recipients of a BK21 fellowship
Letter from C. H. Gensler, Havasupai Agency to Carl Hayden
No full textLetter from C. H. Gensler expressing concern on behalf of the Havasupai Tribe regarding the proposed park boundaries
Iridium-Catalyzed, Hydrosilyl-Directed Borylation of Unactivated Alkyl C–H Bonds
No full textWe report the iridium-catalyzed borylation of primary and secondary alkyl C-H bonds directed by a Si-H group to form alkylboronate esters site selectively. The reactions occur with high selectivity at primary C-H bonds gamma to the hydrosilyl group to form primary alkyl bisboronate esters. In the absence of such primary C-H bonds, the borylation occurs selectively at a secondary C-H bond gamma to the hydrosilyl group, and these reactions of secondary C-H bonds occur with high diastereoselectivity. The hydrosilyl-containing alkyl boronate esters formed by this method undergo transformations selectively at the carbon-boron or carbon-silicon bonds of these products under distinct conditions to give the products of amination, oxidation, and arylation.112318sciescopu
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