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w hydroxylation

Kyungtae Lee, Woojin Lee, Hyo Sug Lee, Jaikwang Shin, Jieun Park, Seongsuk Lee, Samjong Choi, Sueryeon Kim, Jinseong Kim, Youngseon Shim
The decomposition reactions of the Si precursor, diisopropylaminosilane (DIPAS), on W(110) and hydroxylated WO3(001) surfaces are investigated to elucidate the initial reaction mechanism of the atomic layer deposition (ALD) process using density functional theory (DFT) calculations combined with ab initio molecular dynamics (AIMD) simulations. The decomposition reaction of DIPAS on WO3(001) consists of two steps: Si-N dissociative chemisorption and decomposition of SiH3*. It is found that the Si-N bond cleavage of DIPAS is facile on WO3(001) due to hydrogen bonding between the surface OH group and the N atom of DIPAS...
October 12, 2016: Physical Chemistry Chemical Physics: PCCP
A Rugor, M Tataruch, J Staroń, A Dudzik, E Niedzialkowska, P Nowak, A Hogendorf, A Michalik-Zym, D B Napruszewska, A Jarzębski, K Szymańska, W Białas, M Szaleniec
Steroid C25 dehydrogenase (S25DH) from Sterolibacterium denitrificans Chol-1S is a molybdenum oxidoreductase belonging to the so-called ethylbenzene dehydrogenase (EBDH)-like subclass of DMSO reductases capable of the regioselective hydroxylation of cholesterol or cholecalciferol to 25-hydroxy products. Both products are important biologically active molecules: 25-hydroxycholesterol is responsible for a complex regulatory function in the immunological system, while 25-hydroxycholecalciferol (calcifediol) is the activated form of vitamin D3 used in the treatment of rickets and other calcium disorders...
October 11, 2016: Applied Microbiology and Biotechnology
Annewieke J W Verloop, Jean-Paul Vincken, Harry Gruppen
Formation of black tea thearubigins involves at least two of the following oxidation steps: (i) oligomerization, (ii) rearrangement, (iii) hydroxylation. The first two are mainly catalysed by polyphenol oxidase(PPO), whereas the enzyme responsible for hydroxylation has not yet been identified. Two main oxidative activities, peroxidase(POD) and PPO, occur in tea leaves. POD was hypothesized to be responsible for hydroxylation. Model systems with horseradish POD and mushroom tyrosinase were used investigating hydroxylation of theaflavins(TF)...
October 10, 2016: Journal of Agricultural and Food Chemistry
Ayan Pal, Rajat S Das, Weicheng Zhang, Megan Lang, Larry W McLaughlin, Jack W Szostak
The significance of the precise position of the hydroxyl at the 3'-end of an RNA primer for nonenzymatic template-directed primer extension is not well understood. We show that an RNA primer terminating in 3'-hydroxymethyl-2',3'-dideoxy-guanosine has greatly diminished activity, suggesting that the spatial preorganization of the terminal sugar contributes significantly to the efficiency of primer extension.
September 29, 2016: Chemical Communications: Chem Comm
Charles W Schindler, Eric B Thorndike, Masaki Suzuki, Kenner C Rice, Michael H Baumann
BACKGROUND AND PURPOSE: 3,4-Methylenedioxypyrovalerone (MDPV) is a synthetic cathinone with stimulatory cardiovascular effects that can lead to serious medical complications. Here we examined the pharmacological mechanisms underlying these cardiovascular actions of MDPV in conscious rats. EXPERIMENTAL APPROACH: Male Sprague-Dawley rats had telemetry transmitters surgically implanted for the measurement of blood pressure (BP) and heart rate (HR). On test days, rats were placed individually in standard isolation cubicles...
October 7, 2016: British Journal of Pharmacology
Mingxing Qian, Elizabeth B Engler-Chiurazzi, Sara E Lewis, Nigam P Rath, James W Simpkins, Douglas F Covey
Estrone and 17β-estradiol are phenolic steroids that are known to be neuroprotective in multiple models of neuronal injury. Previous studies have identified the importance of their phenolic steroid A-ring for neuroprotection and have identified ortho substituents at the C-2 and C-4 positions on the phenol ring that enhance this activity. To investigate the importance of the steroid ring system for neuroprotective activity, phenolic compounds having the cyclopent[b]anthracene, cyclopenta[b]phenanthrene, benz[f]indene, benz[e]indene, indenes linked to a phenol, and a phenolic spiro ring system were prepared...
October 18, 2016: Organic & Biomolecular Chemistry
Tom H Wright, Ben J Bower, Justin M Chalker, Gonçalo J L Bernardes, Rafal Wiewiora, Wai-Lung Ng, Ritu Raj, Sarah Faulkner, M Robert J Vallée, Anuchit Phanumartwiwath, Oliver D Coleman, Marie-Laëtitia Thézénas, Maola Khan, Sébastien R G Galan, Lukas Lercher, Matthew W Schombs, Stefanie Gerstberger, Maria E Palm-Espling, Andrew J Baldwin, Benedikt M Kessler, Timothy D W Claridge, Shabaz Mohammed, Benjamin G Davis
Posttranslational modification of proteins expands their structural and functional capabilities beyond those directly specified by the genetic code. However, the vast diversity of chemically-plausible (including unnatural but functionally relevant) side-chains is not readily accessible. We describe C (sp(3))-C (sp(3)) bond-forming reactions on proteins under biocompatible conditions, which exploit unusual carbon free radical chemistry, and use them to form Cβ-Cγ bonds with altered side chains. We demonstrate how these transformations enable a wide-diversity of natural, unnatural, posttranslationally-modified (methylated, glycosylated, phosphorylated, hydroxylated) and labeled (fluorinated, isotopically-labeled) side-chains to be added to a common, readily-accessible dehydroalanine precursor in a range of representative protein types and scaffolds...
September 22, 2016: Science
Myrthe W van den Dungen, Dieuwertje E Kok, Anuschka Polder, Ron L A P Hoogenboom, Stefan P J van Leeuwen, Wilma T Steegenga, Ellen Kampman, Albertinka J Murk
Globally, many river sediments are seriously contaminated with persistent organic pollutants (POPs) known to accumulate in aquatic food. In the Netherlands, toxicological risks of human exposure to dioxins and dioxin-like compounds led to a ban on eel fishing in the Rhine-Meuse delta. The aim of this study is to investigate differences in serum POP levels in consumers of eel from high-polluted areas and consumers of eel from low-polluted areas or aquaculture. In total 80 Dutch men were included, aged 40-70 years, with a habitual eel consumption of at least one portion (150 g) per month...
September 30, 2016: Environmental Pollution
Andrzej T Slominski, Tae-Kang Kim, Judith V Hobrath, Allen S W Oak, Edith K Y Tang, Elaine W Tieu, Wei Li, Robert C Tuckey, Anton M Jetten
The classical pathway of vitamin D activation follows the sequence D3→25(OH)D3→1,25(OH)2D3 with the final product acting on the receptor for vitamin D (VDR). An alternative pathway can be started by the action of CYP11A1 on the side chain of D3, primarily producing 20(OH)D3, 22(OH)D3, 20,23(OH)2D3, 20,22(OH)2D3 and 17,20,23(OH)3D3. Some of these metabolites are hydroxylated by CYP27B1 at C1α, by CYP24A1 at C24 and C25, and by CYP27A1 at C25 and C26. The products of these pathways are biologically active...
September 28, 2016: Journal of Steroid Biochemistry and Molecular Biology
Clemens Kanzler, Paul Timo Haase, Helena Schestkowa, Lothar W Kroh
It is well established that a wide range of reductones is formed in the course of the Maillard reaction and that these substances contribute to the oxidative stability of food. The aim of this study was to analyze twelve important heterocyclic intermediates with and without reductone structure as well as structural related substances under equal conditions to compare their antioxidant properties in detail. For this purpose, five methods were selected including photometrical methods like the trolox equivalent antioxidant capacity assay and an electron paramagnetic resonance spectroscopic method...
October 2, 2016: Journal of Agricultural and Food Chemistry
Laurel Mydock-McGrane, Zachary Cusumano, Zhenfu Han, Jana Binkley, Maria Kostakioti, Thomas Hannan, Jerome S Pinkner, Roger Klein, Vasilios Kalas, Jan Crowley, Nigam P Rath, Scott J Hultgren, James W Janetka
Gram-negative uropathogenic Escherichia coli (UPEC) bacteria are a causative pathogen of urinary tract infections (UTIs). Previously developed antivirulence inhibitors of the type 1 pilus adhesin, FimH, demonstrated oral activity in animal models of UTI but were found to have limited compound exposure due to the metabolic instability of the O-glycosidic bond (O-mannosides). Herein, we disclose that compounds having the O-glycosidic bond replaced with carbon linkages had improved stability and inhibitory activity against FimH...
October 14, 2016: Journal of Medicinal Chemistry
Ilona K Jóźwik, Flora M Kiss, Łukasz Gricman, Ammar Abdulmughni, Elisa Brill, Josef Zapp, Juergen Pleiss, Rita Bernhardt, Andy-Mark W H Thunnissen
: Cytochrome P450 monooxygenases (P450s) are attractive enzymes for the pharmaceutical industry, in particular, for applications in steroidal drug synthesis. Here, we report a comprehensive functional and structural characterization of CYP109E1, a novel steroid-converting cytochrome P450 enzyme identified from the genome of Bacillus megaterium DSM319. In vitro and whole-cell in vivo turnover experiments, combined with binding assays, revealed that CYP109E1 is able to hydroxylate testosterone at position 16β...
September 30, 2016: FEBS Journal
D Mannaerts, E Faes, J Gielis, J Briedé, P Cos, E Van Craenenbroeck, W Gyselaers, J Cornette, M Spaanderman, Y Jacquemyn
AIMS: Oxidative stress is crucial in the pathophysiology of preeclampsia. Reactive oxygen species (ROS) like the superoxide radical O2-, are produced by the ischemic placenta, causing systemic inflammation and endothelial dysfunction. EPR uses microwave radiation and a high magnetic field and is the most direct and reliable method to detect free radicals. We explored the feasibility of determining O2- concentration in maternal serum and compared pre-eclamptic and uncomplicated pregnancies...
August 2016: Journal of Maternal-fetal & Neonatal Medicine
Leila Negahdar, Arturo Gonzalez-Quiroga, Daria Otyuskaya, Hilal E Toraman, Li Liu, Johann T B H Jastrzebski, Kevin M Van Geem, Guy B Marin, Joris W Thybaut, Bert M Weckhuysen
Fast pyrolysis bio-oils are feasible energy carriers and a potential source of chemicals. Detailed characterization of bio-oils is essential to further develop its potential use. In this study, quantitative (13)C nuclear magnetic resonance ((13)C NMR) combined with comprehensive two-dimensional gas chromatography (GC × GC) was used to characterize fast pyrolysis bio-oils originated from pinewood, wheat straw, and rapeseed cake. The combination of both techniques provided new information on the chemical composition of bio-oils for further upgrading...
September 6, 2016: ACS Sustainable Chemistry & Engineering
Debjani Si, Mark W Peczuh
The design, synthesis and structural characterization of a new α-d-glucose fused [15]-macrodilactone is reported. The macrolide was synthesized by a route involving sequential acylations of glucose at the C4' and C6' hydroxyl groups followed by an intramolecular Stille reaction previously established for other [15]-macrodilactones. Analysis of the X-ray crystallographic structure of the macrolide revealed a unique conformation of this macrocycle that differs from earlier models for [13]- and [15]-macrodilactones...
August 29, 2016: Carbohydrate Research
Shogo Takahashi, Tatsuki Fukami, Yusuke Masuo, Chad N Brocker, Cen Xie, Kristopher W Krausz, C Roland Wolf, Colin J Henderson, Frank J Gonzalez
Bile acids are synthesized from cholesterol in the liver and subjected to multiple metabolic biotransformations in hepatocytes, including oxidation by cytochromes P450 (CYP)s and conjugation with taurine, glycine, glucuronic acid, and sulfate. Mice and rats can hydroxylate chenodeoxycholic acid (CDCA) at the 6-position to form α-muricholic acid (α-MCA), and ursodeoxycholic acid (UDCA) to form β-muricholic acid (-MCA). However, MCA is not formed in humans to any appreciable degree and the mechanism for this species difference is not known...
September 16, 2016: Journal of Lipid Research
Natalie J German, Haejin Yoon, Rushdia Z Yusuf, J Patrick Murphy, Lydia W S Finley, Gaëlle Laurent, Wilhelm Haas, F Kyle Satterstrom, Jlenia Guarnerio, Elma Zaganjor, Daniel Santos, Pier Paolo Pandolfi, Andrew H Beck, Steven P Gygi, David T Scadden, William G Kaelin, Marcia C Haigis
While much research has examined the use of glucose and glutamine by tumor cells, many cancers instead prefer to metabolize fats. Despite the pervasiveness of this phenotype, knowledge of pathways that drive fatty acid oxidation (FAO) in cancer is limited. Prolyl hydroxylase domain proteins hydroxylate substrate proline residues and have been linked to fuel switching. Here, we reveal that PHD3 rapidly triggers repression of FAO in response to nutrient abundance via hydroxylation of acetyl-coA carboxylase 2 (ACC2)...
September 15, 2016: Molecular Cell
Spencer L Giles, Nicholas W M Heller, Clive R Clayton, Mark E Walker, Mark J Wytiaz, James H Wynne
Novel methods were developed to generate and characterize surface structures formed from polymer segregation within a powder coating system. A blend of unique acrylic polyol resins and low concentrations of matting agent afforded a durable coating exhibiting consistent low reflectance. An enhanced synergistic effect was observed from the phase separation and domain formation of the two polymeric resins with varying pendent hydroxyl group functionality and the incorporated matting agents. Together the domains and incorporated matting agents produced a significantly lower reflectance coating than the matting agent in combination with either polymeric resin alone...
October 5, 2016: ACS Applied Materials & Interfaces
Andrzej T Slominski, Igor Semak, Tobias W Fischer, Tae-Kang Kim, Konrad Kleszczyński, Ruediger Hardeland, Russel J Reiter
Melatonin is produced in almost all living taxa and is probaly 2-3 billion years old. Its pleiotropic activities are related to its local concentration that is secondary to its local synthesis, delivery from distant sites and metabolic or non-enzymatic consumption. This consumption generates metabolites through indolic, kynuric and cytochrome P450 (CYP) mediated hydroxylations and O-demethylation or non-enzymatic processes, with potentially diverse phenotypic effects. While melatonin acts through receptor dependent and independent mechanism, receptors for melatonin metabolites remain to be identified, while their receptor independent activities are well documented...
September 13, 2016: Experimental Dermatology
Na Han, Lin Wang, Zehai Song, Junyu Lin, Chun Ye, Zhihui Liu, Jun Yin
Polysaccharide from the herb of Plantago depressa (PDP) was obtained through ethanol precipitation preceded by a water extraction step. The optimum extraction yield of 5.68±0.46% was obtained with the treatment of raw material in water (w/v, 1:25.34) at 80.44°C during 1.97h, 3.28 times. Under these conditions, obtained yield value was in total agreement with value predicted by the model executed by Box-Behnken design (BBD). Following analysis by IR, HPLC-UV, MS and (1)H NMR, the composition of PDP was found to be l-rhamnose, galactose, arabinose, glucose and d-galacturonic acid...
September 13, 2016: International Journal of Biological Macromolecules
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