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https://www.readbyqxmd.com/read/28087615/microbial-catabolism-of-sterols-focus-on-the-enzymes-that-transform-the-sterol-3%C3%AE-hydroxy-5-en-into-3-keto-4-en
#1
Joseph Kreit
An overview on the microbial sterol catabolism is described with a focus on the catabolic step of the 3β-hydroxy-5-en structure. Cholesterol oxidase transforms this structure into the corresponding 3-keto-4-en feature, and thus initiates the sterol molecule catabolism. The oxidase has been found in a large number of microorganisms, especially in actinobacteria as species of Rhodococcus and Streptomyces Other actinobacteria as species of Mycobacterium and Nocardia possess NAD(P)-dependent dehydrogenase for this catabolic step...
January 12, 2017: FEMS Microbiology Letters
https://www.readbyqxmd.com/read/28078895/enantioselective-%C3%AE-hydroxylation-by-modified-salen-zirconium-iv-catalyzed-oxidation-of-%C3%AE-keto-esters
#2
Fan Yang, Jingnan Zhao, Xiaofei Tang, Guangli Zhou, Wangze Song, Qingwei Meng
The highly enantioselective α-hydroxylation of β-keto esters using cumene hydroperoxide (CHP) as the oxidant was realized by a chiral (1S,2S)-cyclohexanediamine backbone salen-zirconium(IV) complex as the catalyst. A variety of corresponding chiral α-hydroxy β-keto esters were obtained in excellent yields (up to 99%) and enantioselectivities (up to 98% ee). The zirconium-catalyzed enantioselective α-hydroxylation of β-keto esters was scalable, and the zirconium catalyst was recyclable. The reaction can be performed in gram scale, and corresponding chiral products were acquired in 95% yield and 99% ee...
January 12, 2017: Organic Letters
https://www.readbyqxmd.com/read/28067100/effects-of-a-single-bout-of-strenuous-exercise-on-platelet-activation-in-female-apoe-ldlr-mice
#3
K Przyborowski, H Kassassir, M Wojewoda, K Kmiecik, B Sitek, K Siewiera, A Zakrzewska, A M Rudolf, R Kostogrys, C Watala, J A Zoladz, S Chlopicki
Strenuous physical exercise leads to platelet activation that is normally counterbalanced by the production of endothelium-derived anti-platelet mediators, including prostacyclin (PGI2) and nitric oxide (NO). However, in the case of endothelial dysfunction, e.g. in atherosclerosis, there exists an increased risk for intravascular thrombosis during exercise that might be due to an impairment in endothelial anti-platelet mechanisms. In the present work, we evaluated platelet activation at rest and following a single bout of strenuous treadmill exercise in female ApoE/LDLR(-)(/-) mice with early (3-month-old) and advanced (7-month-old) atherosclerosis compared to female age-matched WT mice...
January 9, 2017: Platelets
https://www.readbyqxmd.com/read/28067045/neurotoxicity-of-%C3%AE-keto-amphetamines-deathly-mechanisms-elicited-by-methylone-and-mdpv-in-human-dopaminergic-sh-sy5y-cells
#4
Maria Joao Valente, Maria Lourdes Bastos, Eduarda Fernandes, Félix Carvalho, Paola Guedes de Pinho, Marcia Carvalho
Synthetic cathinones (β-keto amphetamines) act as potent CNS stimulants similarly to classical amphetamines, which raise concerns about their potential neurotoxic effects. The present in vitro study aimed to explore and compare the mechanisms underlying the neurotoxicity of two commonly abused cathinone derivatives, 3,4-methylenedioxymethcathinone (methylone) and 3,4-methylenedioxypyrovalerone (MDPV), with those of 3,4-methylenedioxymethamphetamine (MDMA), using undifferentiated and differentiated SH-SY5Y cells...
January 9, 2017: ACS Chemical Neuroscience
https://www.readbyqxmd.com/read/28062648/dual-chemistry-catalyzed-by-human-acireductone-dioxygenase
#5
Aditi R Deshpande, Thomas C Pochapsky, Gregory A Petsko, Dagmar Ringe
Acireductone dioxygenase (ARD) from the methionine salvage pathway of Klebsiella oxytoca is the only known naturally occurring metalloenzyme that catalyzes different reactions in vivo based solely on the identity of the divalent transition metal ion (Fe(2+) or Ni(2+)) bound in the active site. The iron-containing isozyme catalyzes the cleavage of substrate 1,2-dihydroxy-3-keto-5-(thiomethyl)pent-1-ene (acireductone) by O2 to formate and the ketoacid precursor of methionine, whereas the nickel-containing isozyme uses the same substrates to catalyze an off-pathway shunt to form methylthiopropionate, carbon monoxide and formate...
January 5, 2017: Protein Engineering, Design & Selection: PEDS
https://www.readbyqxmd.com/read/28062431/disseminated-histoplasmosis-presenting-as-diabetic-keto-acidosis-in-an-immunocompetent-patient
#6
Negin Niknam, Prashant Malhotra, Angela Kim, Seth Koenig
Histoplasma capsulatum causes a spectrum of manifestations from asymptomatic to fatal disseminated disease. Disseminated histoplasmosis is mostly seen in endemic areas among immunocompromised patients such as those with AIDS. Here, we present a patient living in a non-endemic area with previously undiagnosed diabetes mellitus, who presented with septic shock and diabetic ketoacidosis (DKA), and was ultimately diagnosed with disseminated histoplasmosis. The patient rapidly recovered on administration of intravenous liposomal amphotericin followed by oral itraconazole...
January 6, 2017: BMJ Case Reports
https://www.readbyqxmd.com/read/28060768/a-novel-osteoporosis-model-with-ascorbic-acid-deficiency-in-akr1a1-gene-knockout-mice
#7
Cheng-Wei Lai, Hsiao-Ling Chen, Min-Yu Tu, Wei-Yu Lin, Theresa Röhrig, Shang-Hsun Yang, Ying-Wei Lan, Kowit-Yu Chong, Chuan-Mu Chen
The AKR1A1 protein is a member of the aldo-keto reductase superfamily that is responsible for the conversion of D-glucuronate to L-gulonate in the ascorbic acid (vitamin C) synthesis pathway. In a pCAG-eGFP transgenic mouse line that was produced by pronuclear microinjection, the integration of the transgene resulted in a 30-kb genomic DNA deletion, including the Akr1A1 gene, and thus caused the knockout (KO) of the Akr1A1 gene and targeting of the eGFP gene. The Akr1A1 KO mice (Akr1A1eGFP/eGFP) exhibited insufficient serum ascorbic acid levels, abnormal bone development and osteoporosis...
January 2, 2017: Oncotarget
https://www.readbyqxmd.com/read/28058946/evaluation-of-eicosanoid-concentrations-in-stored-units-of-canine-packed-red-blood-cells
#8
Rachel R Blake, Jung Hwa Lee, Matt K Ross, Todd M Archer, Robert W Wills, Andrew J Mackin, John M Thomason
OBJECTIVE To evaluate eicosanoid concentrations in freshly prepared canine packed RBCs (PRBCs) and to assess changes in eicosanoid concentrations in PRBC units over time during storage and under transfusion conditions. DESIGN Prospective study. SAMPLE 25 plasma samples from 14 healthy Greyhounds. PROCEDURES Plasma samples were obtained during PRBC preparation (donation samples), and the PRBC units were then stored at 4°C until used for transfusion (≤ 21 days later; n = 17) or mock transfusion if expired (22 to 24 days later; 8)...
January 15, 2017: Journal of the American Veterinary Medical Association
https://www.readbyqxmd.com/read/28058421/excited-state-proton-transfer-in-2-hydroxychalcone-derivatives
#9
Michael Dommett, Rachel Crespo-Otero
Fluorophores exhibiting excited-state intramolecular proton transfer (ESIPT) are promising candidates for applications ranging from imaging and probing to laser dyes, optoelectronic devices and molecular logic gates. Recently, ESIPT-active solid-state emitters based on 2'-hydroxychalcone have been synthesized. The compounds are almost non-emissive in solution but emit in the deep red/NIR region when crystalline. Herein, we present a comprehensive theoretical investigation of the gas-phase excited state relaxation pathways in five 2'-hydroxychalcone systems, using a combination of static and non-adiabatic simulations...
January 6, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28053664/the-coptotermes-gestroi-aldo-keto-reductase-a-multipurpose-enzyme-for-biorefinery-applications
#10
Robson Tramontina, João Paulo L Franco Cairo, Marcelo V Liberato, Fernanda Mandelli, Amanda Sousa, Samantha Santos, Sarita Cândida Rabelo, Bruna Campos, Jaciane Ienczak, Roberto Ruller, André R L Damásio, Fabio Marcio Squina
BACKGROUND: In nature, termites can be considered as a model biological system for biofuel research based on their remarkable efficiency for lignocellulosic biomass conversion. Redox enzymes are of interest in second-generation ethanol production because they promote synergic enzymatic activity with classical hydrolases for lignocellulose saccharification and inactivate fermentation inhibitory compounds produced after lignocellulose pretreatment steps. RESULTS: In the present study, the biochemical and structural characteristics of the Coptotermes gestroi aldo-keto reductase (CgAKR-1) were comprehensively investigated...
2017: Biotechnology for Biofuels
https://www.readbyqxmd.com/read/28052596/synthesis-of-%C3%AE-keto-sulfones-via-a-catalyst-free-reaction-of-aryldiazonium-tetrafluoroborates-sulfur-dioxide-and-silyl-enol-ethers
#11
Tianshuo Liu, Danqing Zheng, Yechun Ding, Xiaona Fan, Jie Wu
A green approach for the generation of β-keto sulfones through a reaction of aryldiazonium tetrafluoroborates, sulfur dioxide, with silyl enol ether under catalyst-free and additive-free conditions is realized. This reaction proceeds efficiently at room temperature, and goes to completion in half an hour. During the reaction process, aryldiazonium tetrafluoroborate would react with DABCO.(SO2)2 to provide sulfonyl radical as the key intermediate, which would initiate the transformation. Oxidants or metal catalysts are avoided, and the presence of DABCO plays an important role in the reaction as well...
January 3, 2017: Chemistry, An Asian Journal
https://www.readbyqxmd.com/read/28052191/engineering-a-thermostable-keto-acid-decarboxylase-using-directed-evolution-and-computationally-directed-protein-design
#12
Lemuel M J Soh, Wai Shun Mak, Paul P Lin, Luo Mi, Frederic Y-H Chen, Robert Damoiseaux, Justin B Siegel, James C Liao
Keto acid decarboxylase (Kdc) is a key enzyme in producing keto acid derived higher alcohols, like isobutanol. The most active Kdc's are found in mesophiles; the only reported Kdc activity in thermophiles is 2 orders of magnitude less active. Therefore, the thermostability of mesophilic Kdc limits isobutanol production temperature. Here, we report development of a thermostable 2-ketoisovalerate decarboxylase (Kivd) with 10.5-fold increased residual activity after 1h preincubation at 60 °C. Starting with mesophilic Lactococcus lactis Kivd, a library was generated using random mutagenesis and approximately 8,000 independent variants were screened...
January 11, 2017: ACS Synthetic Biology
https://www.readbyqxmd.com/read/28039330/dissecting-the-influence-of-two-structural-substituents-on-the-differential-neurotoxic-effects-of-methamphetamine-and-mephedrone-on-dopamine-nerve-endings-with-the-use-of-4-methylmethamphetamine-and-methcathinone
#13
John H Anneken, Mariana Angoa-Perez, Girish C Sati, David Crich, Donald M Kuhn
Mephedrone (MEPH) is a β-ketoamphetamine stimulant drug of abuse that is often a constituent of illicit bath salts formulations. While MEPH bears remarkable similarities to methamphetamine (METH) in terms of chemical structure, as well as its neurochemical and behavioral effects, it has been shown to have a reduced neurotoxic profile compared to METH. The addition of a β-keto moiety and a 4-methyl ring substituent to METH yields MEPH, and a loss of direct neurotoxic potential. In the present study, 2 analogs of METH, methcathinone (MeCa) and 4-methylmethamphetamine (4MM), were assessed for their effects on mouse dopamine (DA) nerve endings to determine the relative contribution of each individual moiety to the loss of direct neurotoxicity in MEPH...
December 30, 2016: Journal of Pharmacology and Experimental Therapeutics
https://www.readbyqxmd.com/read/28029044/oxidative-aza-annulation-of-enynyl-azides-to-2-keto-formyl-1h-pyrroles
#14
Chada Raji Reddy, Sujatarani A Panda, Andhavaram Ramaraju
A method for the construction of pyrroles bearing 2-keto or formyl group through the intramolecular oxidative aza-annulation of enynyl azides is reported for the first time. It involves a sequential carbon-nitrogen/carbon-oxygen bond formations and the combination of AuCl3 with AgSbF6 was identified as suitable reagent system to promote the present reaction. The required enynyl azides are readily prepared from Morita-Baylis-Hillman (MBH) acetates of acetylenic aldehydes.
December 28, 2016: Journal of Organic Chemistry
https://www.readbyqxmd.com/read/28028106/imaginal-feeding-for-progression-of-diapause-phenotype-in-the-two-spotted-spider-mite-acari-tetranychidae
#15
Shoko Kawaguchi, Yuki Manabe, Tatsuya Sugawara, Masahiro Osakabe
Adult females of the two-spotted spider mite (Tetranychus urticae Koch) enter diapause under conditions of short-day length and low temperature. A conspicuous body color change, from greenish yellow to bright orange, accompanies diapause induction. This pigmentation is attributed to accumulation of keto-carotenoids produced internally from β-carotene, which is a precursor of vitamin A essential for inducing diapause. The quantity of β-carotene transferred from females to eggs has been considered sufficient to induce diapause...
December 2016: Environmental Entomology
https://www.readbyqxmd.com/read/28027839/countercurrent-chromatography-separation-of-saponins-by-skeleton-type-from-ampelozizyphus-amazonicus-for-off-line-ultra-high-performance-liquid-chromatography-high-resolution-accurate-mass-spectrometry-analysis-and-characterisation
#16
Fabiana de Souza Figueiredo, Rita Celano, Danila de Sousa Silva, Fernanda das Neves Costa, Peter Hewitson, Svetlana Ignatova, Anna Lisa Piccinelli, Luca Rastrelli, Suzana Guimarães Leitão, Gilda Guimarães Leitão
Ampelozizyphus amazonicus Ducke (Rhamnaceae), a medicinal plant used to prevent malaria, is a climbing shrub, native to the Amazonian region, with jujubogenin glycoside saponins as main compounds. The crude extract of this plant is too complex for any kind of structural identification, and HPLC separation was not sufficient to resolve this issue. Therefore, the aim of this work was to obtain saponin enriched fractions from the bark ethanol extract by countercurrent chromatography (CCC) for further isolation and identification/characterisation of the major saponins by HPLC and MS...
December 19, 2016: Journal of Chromatography. A
https://www.readbyqxmd.com/read/28025170/instability-of-c154y-variant-of-aldo-keto-reductase-1c3
#17
Satoshi Endo, Sayaka Takada, Ryo P Honda, Kathrin Müller, Jochen H Weishaupt, Peter M Andersen, Albert C Ludolph, Yuji O Kamatari, Toshiyuki Matsunaga, Kazuo Kuwata, Ossama El-Kabbani, Akira Ikari
Aldo-keto reductase (AKR) 1C3 is a cytosolic enzyme that metabolizes steroids, prostaglandins, toxic aldehydes and drugs. Recently, some nonsynonymous single nucleotide polymorphisms of AKR1C3 have been suggested to impact steroid and drug metabolism. In this study, we examined the effects of C154Y and L159V variants of AKR1C3 on stability and function of the enzyme. Both variants had been detected in patients with the neurodegenerative disease amyotrophic lateral sclerosis. Recombinant wild-type (WT), C154Y and L159V enzymes were similar in specific activity, but C154Y displayed much lower thermostability than WT and L159V...
December 23, 2016: Chemico-biological Interactions
https://www.readbyqxmd.com/read/28024247/noncovalent-interactions-from-electron-density-topology-and-solvent-effects-on-spectral-properties-of-schiff-bases
#18
S Gandhimathi, C Balakrishnan, M Theetharappan, M A Neelakantan, R Venkataraman
Two Schiff bases were prepared by the condensation of o-allyl substituted 2,4-dihydroxy acetophenone with 1,2-diaminopropane (L1) and ethanediamine (L2) and characterized by elemental analysis, and ESI-MS, IR, UV-Vis, (1)H and (13)C NMR spectral techniques. The effect of solvents with respect to different polarities on UV-Vis and emission spectra of L1 and L2 was investigated at room temperature show that the compounds exist in keto and enol forms in solution and may be attributed to the intramolecular proton transfer in the ground state...
December 13, 2016: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
https://www.readbyqxmd.com/read/28012254/enantioselective-tandem-oxidation-michael-aldol-approaches-to-tetra-substituted-cyclohexanes
#19
Nirmal K Rana, Harshit Joshi, Rupesh K Jha, Vinod Kumar Singh
Enantioselective tandem Michael-aldol and oxidative Michael-aldol approaches have been achieved for the formation of diversely substituted cyclohexanes in total regio-, diastereo- and enantioselective fashion. The presence of nitro, hydroxy and keto groups in the product provides a wide scope for further structural transformations. Furthermore, the utility of the catalytic process is demonstrated in the context of enantioselective formal synthesis of ABT-341, inhibitor.
December 24, 2016: Chemistry: a European Journal
https://www.readbyqxmd.com/read/28012094/clinical-pharmacology-of-the-synthetic-cathinone-mephedrone
#20
Esther Papaseit, José Moltó, Robert Muga, Marta Torrens, Rafael de la Torre, Magí Farré
4-Methyl-N-methylcathinone (mephedrone) is a popular new psychoactive substance (NPS) that is structurally related to the parent compound cathinone, the β-keto analogue of amphetamine. Mephedrone appeared on the street drug market as a substitute for 3,4-methylenedioxy-N-methylamphetamine (MDMA, ecstasy) and was subsequently banned due to the potential health risks associated with its use. Nevertheless, mephedrone continues to be widely consumed among specific populations, with unique patterns of misuse. To date, most information about the biological effects of mephedrone comes from user experiences, epidemiological data, clinical cases, toxicological findings, and animal studies, whilst there are very few data regarding its human pharmacodynamics and pharmacokinetics...
December 24, 2016: Current Topics in Behavioral Neurosciences
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