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Rt isomerism

Beata Morak-Młodawska, Krystian Pluta, Małgorzata Latocha, Małgorzata Jeleń, Dariusz Kuśmierz
New derivatives of two isomeric types of azaphenothiazines, 1,8- and 2,7-diazaphenothiazine, containing the triple bond substituents and additionally tertiary cyclic and acyclic amine groups, were synthesized and tested for their anticancer activity. The compounds exhibited differential inhibitory activities. Better results were obtained when the acetylenic group was transformed via the Mannich reaction to the dialkylaminobutynyl groups. The most active was 2,7-diazaphenothiazine with the N-methylpiperazine-2-butynyl substituent against the human ductal breast epithelial tumor cell line T47D, more potent than cisplatin...
December 2016: Journal of Enzyme Inhibition and Medicinal Chemistry
Flavia Autore, Catherine M Shanahan, Qiuping Zhang
Nesprins are a family of multi-isomeric scaffolding proteins that were originally identified at the nuclear envelope (NE), where they bind to lamin A/C, emerin, and SUN-domain containing proteins, to form the LInker of Nucleoskeleton-and-Cytoskeleton (LINC) complex that connects the NE to the actin cytoskeleton. However, nesprin genes also give rise to a variety of tissue-specific variants of different sizes with potential roles beyond the NE. These variants are generated through alternative initiation, termination, and splicing, which makes nesprin biology very complex to study due to the difficulty in generating specific antibodies and/or short interfering RNAs (siRNA) to particular isoforms...
2016: Methods in Molecular Biology
Xiaolei Zheng, Gaohong Zhai, Wanqing Gao, Yibo Lei, Le Yu, Chaoyuan Zhu
We have employed the SA2-CAS(4,4)/6-31G ab initio method together with an on-the-fly global-switching trajectory surface hopping algorithm to simulate photoisomerization reaction dynamics from reactant trans, trans-1,4-diphenyl-1,3-butadiene (DPB) to products cis,trans-DPB and cis,cis-DPB. This topic has been extensively studied experimentally and the present theoretical study is the first to simulate DPB photoisomerization reaction dynamics as far as we know. With total 600 sampling trajectories, 300 actively contribute to isomerization reaction via two conical intersections between the electronic ground and the first excited states...
April 7, 2016: Physical Chemistry Chemical Physics: PCCP
Hongkai Zhu, Hongwen Sun, Yanwei Zhang, Jiayao Xu, Bing Li, Qixing Zhou
To study the uptake pathways of 3 main hexabromocyclododecane diastereoisomers (α-, β-, and γ-HBCDs) in wheat, four closed chambers were designed to expose wheat to HBCDs via air and/or soil for 4 weeks. The results showed that HBCDs could be absorbed by wheat both via root from soil and via leaf from air. The Rt values (ratio of HBCDs from root-to-leaf translocation to the total accumulation in leaves) ranging from 14.4 to 29.8% suggested that acropetal translocation within wheat was limited. A negative linear relationship was found between log Rt and log Kow of the HBCD diastereoisomers (p < 0...
March 1, 2016: Environmental Science & Technology
V S Lima, A C Pinto, M S Rafael
The yellow fever mosquito Aedes (Stegomyia) aegypti is the main vector of dengue arbovirus and other arboviruses. Dengue prevention measures for the control of A. aegypti involve mainly the use of synthetic insecticides. The constant use of insecticides has caused resistance in this mosquito. Alternative studies on plant extracts and their products have been conducted with the aim of controlling the spread of the mosquito. Dillapiole is a compound found in essential oils of the plant Piper aduncum (Piperaceae) which has been effective as a biopesticide against A...
2015: Genetics and Molecular Research: GMR
Rosa Becerra, J Pat Cannady, Christian Pfrang, Robin Walsh
Time-resolved kinetics studies of silylene, SiH2, generated by laser flash photolysis of phenylsilane, were performed to obtain rate coefficients for its bimolecular reaction with 2,5-dihydrofuran (2,5-DHF). The reaction was studied in the gas phase over the pressure range of 1-100 Torr in SF6 bath gas, at five temperatures in the range of 296-598 K. The reaction showed pressure dependences characteristic of a third body assisted association. The second-order rate coefficients obtained by Rice-Ramsperger-Kassel-Marcus (RRKM)-assisted extrapolation to the high-pressure limit at each temperature fitted the following Arrhenius equation where the error limits are single standard deviations: log(k/cm(3) molecule(-1) s(-1)) = (-9...
November 19, 2015: Journal of Physical Chemistry. A
Marie Médoc, Franck Sobrio
The efficient dehydrofluorination and radiofluorination of N,N-disubstituted-β-aminoalcohols through an anchimeric-assisted mechanism was developed. An investigation into the influence of N-substituents on the ring opening of the aziridinium intermediate indicated differences in the isomeric ratio and the yields of fluorinated products obtained from N,N-disubstituted-phenylalaninol. This influence was substantial for (18)F-radiofluorination, with yields varying from 0 to 71% at room temperature (RT). Although no significant effects were observed in the fluorine-19 chemistry when the reaction was heated to 90 °C, considerable changes appeared during radiofluorination...
October 16, 2015: Journal of Organic Chemistry
Jan Stanstrup, Steffen Neumann, Urška Vrhovšek
Demands in research investigating small molecules by applying untargeted approaches have been a key motivator for the development of repositories for mass spectrometry spectra and automated tools to aid compound identification. Comparatively little attention has been afforded to using retention times (RTs) to distinguish compounds and for liquid chromatography there are currently no coordinated efforts to share and exploit RT information. We therefore present PredRet; the first tool that makes community sharing of RT information possible across laboratories and chromatographic systems (CSs)...
September 15, 2015: Analytical Chemistry
E W Kaiser, David S Pierce
The equilibrium constants for the Z to E isomerizations of CF3CF═CHF (K1) and CF3CH═CHCF3 (K2) have been measured using GC/FID analysis over the temperature ranges 360–850 and 297–850 K, respectively. At lower temperature, K was determined using Cl atom catalysis. At higher temperature, K was measured without a catalyst. The temperature-dependent expressions are K1 (Z to E) = 1.45(±0.15)e(–[2845(±100)/RT]) and K2 (Z to E) = 1.9(±0.22)e(+[4330(±120)/RT]) (where the gas constant R ≡ 1.986 cal mol(–1) K(–1))...
August 27, 2015: Journal of Physical Chemistry. A
Xiuli Sun, Meiyun Fang, Yanchun Guan, Yang Si, Liangliang Ma, Yi Wang, Zhilin Jia
Alternative splicing of the glucocorticoid receptor (GR) gene results in several GR isoforms, we examined their expression (GRα, GRβ, GRγ and GR-P) by real-time RT-PCR in glucocorticoid (GC) sensitive (CEM-C7), GC resistant (CEM-C1) cells and adult acute lymphoblastic leukemia (ALL) patients, to determine the association of GR isoform expression profiles and GC resistance in adult ALL patients. With GC treatment, GR levels in C1 cells showed no obvious changes. In C7 cells, the mRNA levels of GRα, GRβ and GRγ first increased and then decreased, whereas GR-P mRNA had a continued rising trend...
May 2015: Die Pharmazie
Xunhai Zheng, Lalith Perera, Geoffrey A Mueller, Eugene F DeRose, Robert E London
HIV-1 reverse transcriptase utilizes a metamorphic polymerase domain that is able to adopt two alternate structures that fulfill catalytic and structural roles, thereby minimizing its coding requirements. This ambiguity introduces folding challenges that are met by a complex maturation process. We have investigated this conformational maturation using NMR studies of methyl-labeled RT for the slower processes in combination with molecular dynamics simulations for rapid processes. Starting from an inactive conformation, the p66 precursor undergoes a unimolecular isomerization to a structure similar to its active form, exposing a large hydrophobic surface that facilitates initial homodimer formation...
2015: ELife
Nancy Faßheber, Nathalie Lamoureux, Gernot Friedrichs
Bimolecular reactions of the NCN radical play a key role in modeling prompt-NO formation in hydrocarbon flames. The rate constant of the so-far neglected reaction NCN + H2 has been experimentally determined behind shock waves under pseudo-first order conditions with H2 as the excess component. NCN3 thermal decomposition has been used as a quantitative high temperature source of NCN radicals, which have been sensitively detected by difference UV laser absorption spectroscopy at [small nu, Greek, tilde] = 30383...
June 28, 2015: Physical Chemistry Chemical Physics: PCCP
Anna Busch, Núria González-García, György Lendvay, Matthias Olzmann
The thermal decomposition of cyanonitrene, NCN, was studied behind reflected shock waves in the temperature range 1790-2960 K at pressures near 1 and 4 bar. Highly diluted mixtures of NCN3 in argon were shock-heated to produce NCN, and concentration-time profiles of C atoms as reaction product were monitored with atomic resonance absorption spectroscopy at 156.1 nm. Calibration was performed with methane pyrolysis experiments. Rate coefficients for the reaction (3)NCN + M → (3)C + N2 + M (R1) were determined from the initial slopes of the C atom concentration-time profiles...
July 16, 2015: Journal of Physical Chemistry. A
Abdellatif Bahaji, Ángela M Sánchez-López, Nuria De Diego, Francisco J Muñoz, Edurne Baroja-Fernández, Jun Li, Adriana Ricarte-Bermejo, Marouane Baslam, Iker Aranjuelo, Goizeder Almagro, Jan F Humplík, Ondřej Novák, Lukáš Spíchal, Karel Doležal, Javier Pozueta-Romero
Phosphoglucose isomerase (PGI) catalyzes the reversible isomerization of glucose-6-phosphate and fructose-6-phosphate. It is involved in glycolysis and in the regeneration of glucose-6-P molecules in the oxidative pentose phosphate pathway (OPPP). In chloroplasts of illuminated mesophyll cells PGI also connects the Calvin-Benson cycle with the starch biosynthetic pathway. In this work we isolated pgi1-3, a mutant totally lacking pPGI activity as a consequence of aberrant intron splicing of the pPGI encoding gene, PGI1...
2015: PloS One
Meng-Yang Chang, Yu-Chieh Cheng, Yi-Ju Lu
A novel Bi(OTf)3-mediated cycloisomerization of γ-alkynyl arylketones 4, 7, or 10 with molecular sieve (MS) in MeNO2 affords 3-substituted furans 3, 8, or 11 at rt for 3 h in moderate to good yields. The method provides mild, less-toxic, atom-economic and efficient conditions. The mechanism has been studied and proposed. Moreover, this route can be enlarged to gram scale.
March 6, 2015: Organic Letters
Radhe Shyam Bahare, Swastika Ganguly, Kiattawee Choowongkomon, Supaporn Seetaha
BACKGROUND: Structural modifications of thiazolidinediones at 3rd and 5th position have exhibited significant biological activities. In view of the facts, and based on in silico studies carried out on thiazolidine-2,4-diones as HIV-1- RT inhibitors, a novel series of 2,4-thiazolidinedione analogs have been designed and synthesized. METHODS: Title compounds were prepared by the reported method. Conformations of the structures were assigned on the basis of results of different spectral data...
2015: Daru: Journal of Faculty of Pharmacy, Tehran University of Medical Sciences
Jun Jiang, Jie Li, Xiaobin Jia
Central-icaritin (CIT) is a flavonoid aglycone first discovered in our laboratory, which is an isomeric aglycone of icaritin (IT). We wanted to know whether CIT also had anti-osteoporosis activity. In this study, CIT was investigated in an ovariectomized rat (OVX) model. Fifty-six 6-month old female Sprague-Dawley rats were randomly assigned to sham operated group (Sham) and six OVX subgroups (n=8 each). The OVX rats were then subdivided into six groups treated with vehicle (OVX), icaritin (IT, 40 mg/kg body weight/day), estradiol valerate (EV, 100 μg/kg body weight/day) or CIT (10, 20, and 40 mg/kg body weight/day) for 12 weeks, respectively...
2014: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
Formijn J van Hemert, Ben Berkhout, Hans L Zaaijer
INTRODUCTION: Resistance of the reverse transcriptase (RT) of hepatitis B virus (HBV) to the tenofovir nucleotide drug has not been observed since its introduction for treatment of hepatitis B virus (HBV) infection in 2008. In contrast, frequent viral breakthrough and resistance has been documented for adefovir. Our computational study addresses an inventory of the structural differences between these two nucleotide analogues and their binding sites and affinities to wildtype (wt) and mutant RT enzyme structures based on in silico modeling, in comparison with the natural nucleotide substrates...
2014: PloS One
Marina Kovaliov, Chaim Wachtel, Eylon Yavin, Bilha Fischer
Nowadays, most nucleic acid detections using fluorescent probes rely on quenching of fluorescence by energy transfer from one fluorophore to another or to a non-fluorescent molecule (quencher). The most widely used quencher in fluorescent probes is 4-((4-(dimethylamino)phenyl)azo)benzoic acid (DABCYL). We targeted a nucleoside-DABCYL analogue which could be incorporated anywhere in an oligonucleotide sequence and in any number, and used as a quencher in different hybridization sensitive probes. Specifically, we introduced a 5-(4-((dimethylamino)phenyl)azo)benzene)-2'-deoxy-uridine (dU(DAB)) quencher...
October 21, 2014: Organic & Biomolecular Chemistry
N Sharath, K P J Reddy, E Arunan
Thermal decomposition of propargyl alcohol (C3H3OH), a molecule of interest in interstellar chemistry and combustion, was investigated using a single pulse shock tube in the temperature ranging from 953 to 1262 K. The products identified include acetylene, propyne, vinylacetylene, propynal, propenal, and benzene. The experimentally observed overall rate constant for thermal decomposition of propargyl alcohol was found to be k = 10((10.17 ± 0.36)) exp(-(39.70 ± 1.83)/RT) s(-1). Ab initio theoretical calculations were carried out to understand the potential energy surfaces involved in the primary and secondary steps of propargyl alcohol thermal decomposition...
August 7, 2014: Journal of Physical Chemistry. A
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