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Organic chemistry*

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https://www.readbyqxmd.com/read/29792672/biosynthesis-of-lincosamide-antibiotics-reactions-associated-with-degradation-and-detoxification-pathways-play-a-constructive-role
#1
Daozhong Zhang, Zhijun Tang, Wen Liu
Natural products typically are small molecules produced by living organisms. These products possess a wide variety of biological activities and thus have historically played a critical role in medicinal chemistry and chemical biology either as chemotherapeutic agents or as useful tools. Natural products are not synthesized for use by human beings; rather, living organisms produce them in response to various biochemical processes and environmental concerns, both internal and external. These processes/concerns are often dynamic and thus motivate the diversification, optimization, and selection of small molecules in line with changes in biological function...
May 24, 2018: Accounts of Chemical Research
https://www.readbyqxmd.com/read/29792422/toward-total-synthesis-of-thiolate-protected-metal-nanoclusters
#2
Qiaofeng Yao, Tiankai Chen, Xun Yuan, Jianping Xie
Total synthesis, where desired organic- and/or biomolecules could be produced from simple precursors at atomic precision and with known step-by-step reactions, has prompted centuries-lasting bloom of organic chemistry since its conceptualization in 1828 (Wöhler synthesis of urea). Such expressive science is also highly desirable in nanoscience, since it represents a decisive step toward atom-by-atom customization of nanomaterials for basic and applied research. Although total synthesis chemistry is less established in nanoscience, recent years have witnessed seminal advances and increasing research efforts devoted into this field...
May 24, 2018: Accounts of Chemical Research
https://www.readbyqxmd.com/read/29792329/residual-complexity-does-impact-organic-chemistry-and-drug-discovery-the-case-of-rufomyazine-and-rufomycin
#3
Mary P Choules, Larry L Klein, David C Lankin, James B McAlpine, Sang-Hyun Cho, Jinhua Cheng, Hanki Lee, Joo-Won Suh, Birgit U Jaki, Scott G Franzblau, Guido F Pauli
Residual complexity (RC) involves the impact of subtle but critical structural and biological features on drug lead validation, including unexplained effects related to unidentified impurities. RC commonly plagues drug discovery efforts due to the inherent imperfections of chromatographic separation methods. The new diketopiperazine, rufomyazine (6), and the previously known antibiotic, rufomycin (7), represent a prototypical case of RC that (almost) resulted in the misassignment of biological activity. The case exemplifies that impurities well below the natural abundance of 13 C (1...
May 24, 2018: Journal of Organic Chemistry
https://www.readbyqxmd.com/read/29791132/ptml-model-of-chembl-data-for-dopamine-targets-docking-synthesis-and-assay-of-new-plg-peptidomimetics
#4
Joana Ferreira da Costa, David Silva, Olga Caamaño, José M Brea, Maria Isabel Loza, Cristian R Munteanu, Alejandro Pazos, Xerardo García-Mera, Humbert González-Díaz
Predicting Drug-Protein Interactions (DPIs) for target proteins involved in Dopamine pathways is very important goal in medicinal chemistry. We can tackle this problem using Molecular Docking or Machine Learning (ML) models for one specific protein. Unfortunately, these models fail to account for large and complex Big Data sets of preclinical assays reported in public databases. This includes multiple conditions of assay like different experimental parameters, biological assays, target proteins, cell lines, organism of the target, organism of assay, etc...
May 23, 2018: ACS Chemical Neuroscience
https://www.readbyqxmd.com/read/29790879/exploring-matrix-effects-and-quantifying-organic-additives-in-hydraulic-fracturing-associated-fluids-using-liquid-chromatography-electrospray-ionization-mass-spectrometry
#5
Marika Nell, Damian E Helbling
Hydraulic fracturing (HF) operations utilize millions of gallons of water amended with chemical additives including biocides, corrosion inhibitors, and surfactants. Fluids injected into the subsurface return to the surface as wastewaters, which contain a complex mixture of additives, transformation products, and geogenic chemical constituents. Quantitative analytical methods are needed to evaluate wastewater disposal alternatives or to conduct adequate exposure assessments. However, our narrow understanding of how matrix effects change the ionization efficiency of target analytes limits the quantitative analysis of polar to semi-polar HF additives by means of liquid chromatography electrospray ionization mass spectrometry (LC-ESI-MS)...
May 23, 2018: Environmental Science. Processes & Impacts
https://www.readbyqxmd.com/read/29790289/catalytic-space-engineering-in-porphyrin-metal-organic-frameworks-for-combinatorial-co2-capture-and-conversion-under-low-concentration
#6
Li Zhang, Jiewei Liu, Yan-Zhong Fan, Xin Li, Yao-Wei Xu, Cheng-Yong Su
Porous porphyrin metal-organic frameworks (PMOFs) provide a promising platform to study CO2 capture and conversion (C3) owing to their versatility in photoelectric, catalytic and redox activities and porphyrin coordination chemistry. Herein, we report the C3 application of two PMOFs by engineering the coordination space through introduction of two catalytic metalloporphyrins, Rh-PMOF-1 and Ir-PMOF-1, both of which can serve as heterogeneous catalysts for the chemical fixation of CO2 into cyclic carbonates with up to 99% yields...
May 22, 2018: ChemSusChem
https://www.readbyqxmd.com/read/29790219/metal-organic-frameworks-based-on-multicentre-bonded-mi-8-m-mn-zn-clusters-with-cubic-aromaticity
#7
Bin Zhao, Huan-Cheng Hu
A new concept for constructing metal-organic frameworks (MOFs) based on multicentre-bonded [MI]8 (M = Mn, Zn) clusters with cubic aromaticity is discussed. In principle, intermolecular/intramolecular hydrogen-bonding, π***π stacking, coordinated covalent bonding and ionic bonding usually account for the structures of MOFs, and multicentered bonds generally exist in cation, anion, neutral and zwitterionic radicals, while rarely appear in MOFs. Meanwhile, aromaticity became one of the most vexing yet fascinating key concepts in chemistry since the proposition of the structure of benzene molecule in 1865...
May 23, 2018: Chemistry: a European Journal
https://www.readbyqxmd.com/read/29788887/designing-peptidomimetics
#8
Juan J Perez
The concept of a peptidomimetic was coined about forty years ago. Since then, an enormous effort and interest has been devoted to mimic the properties of peptides with small molecules or pseudopeptides. The present report aims to review different approaches described in the past to succeed in this goal. Basically, there are two different approaches to design peptidomimetics: a medicinal chemistry approach, where parts of the peptide are successively replaced by non-peptide moieties until getting a non-peptide molecule and a biophysical approach, where a hypothesis of the bioactive form of the peptide is sketched and peptidomimetics are designed based on hanging the appropriate chemical moieties on diverse scaffolds...
May 21, 2018: Current Topics in Medicinal Chemistry
https://www.readbyqxmd.com/read/29787626/organotin-selenide-clusters-and-hybrid-capsules
#9
Stefanie Dehnen, Katharina Hanau, Niklas Rinn, Mario Argentari
Several compounds with unique structural motifs that have already been known from organotin sulfide chemistry, but remained unprecedented in organotin selenide chemistry so far, have been synthesized. The reaction of [(R1Sn)4Se6] (R1 = CMe2CH2C(O)Me) with N2H4·H2O/(SiMe3)2Se and with PhN2H3/(SiMe3)2Se led to the formation of [{(R2Sn)2SnSe4}2(µ-Se)2] (1) and [{(R3Sn)2SnSe4}2(µ-Se)2] (2) (R2 = CMe2CH2C(Me)NNH2, R3 = CMe2CH2C(Me)NNPhH), respectively. Addition of o-phthalaldehyde to [(R2Sn)4Se6] yielded a cluster with intramolecular bridging of the organic groups, [(R4Sn2)2Se6] (3, R4 = (CMe2CH2C(Me)NNCH)2C6H4)...
May 22, 2018: Chemistry: a European Journal
https://www.readbyqxmd.com/read/29786909/a-new-composite-electrode-applied-for-studying-the-electrochemistry-of-insoluble-particles-%C3%AE-hgs
#10
Minjun Yang, Richard G Compton
The redox chemistry of solid α-HgS particles is revealed using a carbon/PVDF composite containing α-HgS, carbon black, polyvinylidene fluoride (PVDF). The electrochemical behaviour of the carbon/PVDF composite is first characterised with three water insoluble organic solids. Then the reduction of solid α-HgS particles is investigated and found to occur at a high negative potential, -1.82V vs saturated mercury sulphate reference electrode, to form metallic mercury and sulphide ions. The subsequent oxidation of metallic mercury and sulphide occurs at +0...
May 22, 2018: Chemistry: a European Journal
https://www.readbyqxmd.com/read/29785762/special-award-in-synthetic-organic-chemistry-japan-for-koji-nakanishi-european-federation-for-medicinal-chemistry-awards
#11
(no author information available yet)
No abstract text is available yet for this article.
May 22, 2018: Angewandte Chemie
https://www.readbyqxmd.com/read/29785499/on-the-current-role-of-hydratases-in-biocatalysis
#12
REVIEW
Matthias Engleder, Harald Pichler
Water addition to carbon-carbon double bonds provides access to value-added products from inexpensive organic feedstock. This interesting but relatively little-studied reaction is catalysed by hydratases in a highly regio- and enantiospecific fashion with excellent atom economy. Considering that asymmetric hydration of (non-activated) carbon-carbon double bonds is virtually impossible with current organic chemistry, enzymatic hydration reactions are highly attractive for industrial applications. Hydratases have been known for several decades but their biocatalytic potential has only been explored over the past 15 years...
May 21, 2018: Applied Microbiology and Biotechnology
https://www.readbyqxmd.com/read/29785431/slow-magnetic-relaxation-and-luminescence-properties-in-lanthanide-iii-anil-complexes
#13
Diamantoula Maniaki, Ioannis Mylonas-Margaritis, Julia Mayans, Aikaterini Savvidou, Catherine P Raptopoulou, Vlasoula Bekiari, Vassilis Psycharis, Albert Escuer, Spyros P Perlepes
The initial use of anils, i.e. bidentate Schiff bases derived from the condensation of anilines with salicylaldehyde or its derivatives, in 4f-metal chemistry is described. The 1 : 1 reactions between Ln(NO3)3·xH2O (Ln = lanthanide) or Y(NO3)3·6H2O and N-(5-bromosalicylidene)aniline (5BrsalanH) in MeCN has provided access to complexes [Ln(NO3)3(5BrsalanH)2(H2O)]·MeCN (Ln = Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Yb) and [Y(NO3)3(5BrsalanH)2(H2O)]·MeCN, respectively, in good yields. The structures of the isomorphous complexes with Ln = Pr(1·MeCN), Sm(3·MeCN), Gd(5·MeCN), Dy(7·MeCN) and Er(9·MeCN) have been determined by single-crystal X-ray crystallography...
May 22, 2018: Dalton Transactions: An International Journal of Inorganic Chemistry
https://www.readbyqxmd.com/read/29782690/stable-carboxylate-terminated-gold-surfaces-produced-by-spontaneous-grafting-of-an-alkyl-tin-compound
#14
Mayreli Ortiz, Ahmed Mehdi, Christophe Methivier, Serge Thorimbert, Bernold Hasenknopf, Ciara K O'Sullivan
Self-assembled monolayers formed by chemisorption of thiolated molecules on gold surfaces are widely applied for biosensing. Moreover, and due to the low stability of thiol-gold chemistry, contributions to the functionalisation of gold substrates with linkers that provide a more stable platform for the immobilisation of electroactive or biological molecules are highly appreciated. In the work reported here, we demonstrate that a carboxylated organotin compound can be successfully grafted onto gold substrates to form a highly stable organic layer with reactivity for subsequent binding to an aminated molecule...
May 21, 2018: Chemistry: a European Journal
https://www.readbyqxmd.com/read/29782519/increased-circulating-microrna-122-is-a-biomarker-for-discrimination-and-risk-stratification-in-patients-defined-by-sepsis-3-criteria
#15
Tim Rahmel, Simon T Schäfer, Ulrich H Frey, Michael Adamzik, Jürgen Peters
BACKGROUND: Sepsis is now operationally defined as life-threatening organ dysfunction caused by an infection, identified by an acute change in SOFA-Score of at least two points, including clinical chemistry such as creatinine or bilirubin concentrations. However, little knowledge exists about organ-specific microRNAs as potentially new biomarkers. Accordingly, we tested the hypotheses that micro-RNA-122, the foremost liver-related micro-RNA (miR), 1) discriminates between sepsis and infection, 2) is an early predictor for mortality, and 3) improves the prognostic value of the SOFA-score...
2018: PloS One
https://www.readbyqxmd.com/read/29782168/rapid-aqueous-phase-hydrolysis-of-ester-hydroperoxides-arising-from-criegee-intermediates-and-organic-acids
#16
Ran Zhao, Christopher M Kenseth, Yuanlong Huang, Nathan F Dalleska, Xiaobi Michelle Kuang, Jierou Chen, Suzanne E Paulson, John H Seinfeld
Stabilized Criegee intermediates react with organic acids in the gas phase and at the air-water interface to form a class of ester hydroperoxides, α-acyloxyalkyl hydroperoxides (αAAHPs). A number of recent studies have proposed the importance of αAAHPs to the formation and growth of secondary organic aerosol (SOA). The chemistry of αAAHPs has not been investigated due to a lack of commercially available chemical standards. In this work, the behavior of αAAHPs in condensed phases is investigated for the first time...
May 21, 2018: Journal of Physical Chemistry. A
https://www.readbyqxmd.com/read/29780983/the-predictive-power-of-aromaticity-quantitative-correlation-between-aromaticity-and-ionization-potentials-and-homo-lumo-gaps-in-oligomers-of-benzene-pyrrole-furan-and-thiophene
#17
Renana Gershoni-Poranne, Anuja P Rahalkar, Amnon Stanger
Aromaticity is a central and ubiquitous concept in organic chemistry, and is used extensively to explain various phenomena. Yet, aromaticity cannot be observed or measured as a property in its own right and, to date, only qualitative and semi-quantitative relationships have been described between aromaticity and an observable property. We now demonstrate for the first time a robust quantitative relationship between the HOMO-LUMO gap and adiabatic ionization potential of a polycyclic aromatic hydrocarbon oligomer - both measurable physical quantities - and its aromaticity, as quantified by the Nucleus Independent Chemical Shift (NICS) index...
May 21, 2018: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/29780551/protein-surface-functionalisation-as-a-general-strategy-for-facilitating-biomimetic-mineralisation-of-zif-8
#18
Natasha K Maddigan, Andrew Tarzia, David M Huang, Christopher J Sumby, Stephen G Bell, Paolo Falcaro, Christian J Doonan
The durability of enzymes in harsh conditions can be enhanced by encapsulation within metal-organic frameworks (MOFs) via a process called biomimetic mineralisation. Herein we show that the surface charge and chemistry of a protein determines its ability to seed MOF growth. We demonstrate that chemical modification of amino acids on the protein surface is an effective method for systematically controlling biomimetic mineralisation by zeolitic imidazolate framework-8 (ZIF-8). Reaction of surface lysine residues with succinic (or acetic) anhydride facilitates biomimetic mineralisation by increasing the surface negative charge, whereas reaction of surface carboxylate moieties with ethylenediamine affords a more positively charged protein and hinders the process...
May 14, 2018: Chemical Science
https://www.readbyqxmd.com/read/29779661/characterization-and-biochemical-assays-of-streptomyces-vanadium-dependent-chloroperoxidases
#19
Shaun M K McKinnie, Zachary D Miles, Bradley S Moore
Vanadium-dependent haloperoxidases (VHPOs) are fascinating enzymes that facilitate electrophilic halogen incorporation into electron-rich substrates, simply requiring vanadate, a halide source, and cosubstrate hydrogen peroxide for activity. Initially characterized in fungi and red algae, VHPOs were long believed to have limited regio-, chemo-, and enantioselectivity in the production of halogenated metabolites. However, the recent discovery of homologues in the biosynthetic gene clusters of the stereoselectively halogenated meroterpenoids from marine-derived Streptomyces bacteria has revised this paradigm...
2018: Methods in Enzymology
https://www.readbyqxmd.com/read/29778594/differetial-toxin-profiles-of-ciguatoxins-in-marine-organisms-chemistry-fate-and-global-distribution
#20
REVIEW
Lucía Soliño, Pedro Reis Costa
Ciguatoxins (CTXs) are fish metabolism products and a result of biotransformation of precursor gambiertoxins produced, in the first instance, by benthic dinoflagellates Gambierdiscus and Fukuyoa. Ciguatoxins are potent neurotoxins that selectively open voltage gated sodium channels in excitable cells causing the human food poisoning known as Ciguatera (CFP). Endemic from tropical areas in central Pacific and West Indian Ocean, and the Caribbean Sea, CTX may affects up to 500,000 people annually due to fish consumption...
May 17, 2018: Toxicon: Official Journal of the International Society on Toxinology
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