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María M Adeva-Andany, Laura López-Maside, Cristóbal Donapetry-García, Carlos Fernández-Fernández, Cristina Sixto-Leal
Branched-chain amino acids (leucine, isoleucine and valine) are structurally related to branched-chain fatty acids. Leucine is 2-amino-4-methyl-pentanoic acid, isoleucine is 2-amino-3-methyl-pentanoic acid, and valine is 2-amino-3-methyl-butanoic acid. Similar to fatty acid oxidation, leucine and isoleucine produce acetyl-coA. Additionally, leucine generates acetoacetate and isoleucine yields propionyl-coA. Valine oxidation produces propionyl-coA, which is converted into methylmalonyl-coA and succinyl-coA. Branched-chain aminotransferase catalyzes the first reaction in the catabolic pathway of branched-chain amino acids, a reversible transamination that converts branched-chain amino acids into branched-chain ketoacids...
March 21, 2017: Amino Acids
Gulshan R Walke, Dnyanesh S Ranade, Shefali N Ramteke, Srikanth Rapole, Cristina Satriano, Enrico Rizzarelli, Gaetano A Tomaselli, Giuseppe Trusso Sfrazzetto, Prasad P Kulkarni
A variety of fluorescent probes are proposed to monitor the intracellular copper content. So far, none of the probes have been evaluated for their potential to inhibit copper-associated intracellular oxidative stress. Herein, we studied the ability of a fluorescent copper probe, OBEP-CS1, to inhibit intracellular oxidative stress associated with an amyloid β (Aβ) peptide-copper complex. The data showed that OBEP-CS1 completely inhibits the copper-catalyzed oxidation as well as decarboxylation/deamination of Aβ1-16...
March 20, 2017: Inorganic Chemistry
Yuan Yuan, Adrienne Tarres, Thomas Bessaire, Wilhelm Rademacher, Richard H Stadler, Thierry Delatour
Mepiquat (N,N-dimethylpiperidinium) is a plant growth regulator registered for use as its chloride salt in many countries on cereals and other crops. Recent model system studies have shown that natural chemicals present in crop plants, such as pipecolic acid and pipecolic acid betaine, may furnish mepiquat through different chemical pathways, when subjected to temperatures in the range of 200°C. In this study, we cooked raw vegetables that did not contain mepiquat to a palatable state using different traditional cooking methods, and detected mepiquat in 9 out of 11 oven-cooked vegetables, reaching up to 189μg/kg dry wt in oven-cooked broccoli...
August 1, 2017: Food Chemistry
Asif Noor, Jiawei Li, George N Khairallah, Zhen Li, Hossein Ghari, Allan J Canty, Alireza Ariafard, Paul S Donnelly, Richard A J O'Hair
A new palladium mediated "one pot" synthesis of thioamides from aromatic carboxylic acids (ArCO2H + RNCS → ArC(S)NHR + CO2) was discovered by gas-phase experiments and theoretical studies. Palladium-mediated decarboxylation of aromatic carboxylic acids followed by addition of substituted isothiocyanates leads to the corresponding thioamide derivatives.
March 20, 2017: Chemical Communications: Chem Comm
Stephen G Davies, Ai M Fletcher, Paul M Roberts, James E Thomson, David Zimmer
(-)-Pseudodistomin E has been prepared for the first time, allowing its structure and absolute configuration to be confirmed. The established conjugate addition of lithium (S)-N-allyl-N-(α-methyl-p-methoxybenzyl)amide to methyl (E,E)-hepta-2,5-dienoate generated the C(2)-stereocenter, and iodolactonisation of a derivative generated the remaining two stereogenic centers. Ensuing iodide displacement was achieved using a tethering strategy, to introduce the nitrogen atom to C(5). Decarboxylative coupling of a carboxylic acid with a dialkylzinc reagent completed construction of the tridecadienyl chain...
March 17, 2017: Organic Letters
Azusa Kondoh, Yuji Kamata, Masahiro Terada
An efficient synthesis of enantioenriched γ-amino-α,β-unsaturated esters was developed by utilizing the palladium-catalyzed decarboxylative rearrangement of enantioenriched allylic carbamates possessing an ester moiety at the allylic position. The reaction proceeded in good yield with a high degree of chirality transfer by making use of Xantphos as a superior ligand for the catalyst. The products directly participated in the formal [3 + 2] cycloaddition reaction with tosyl isocyanate under Brønsted base catalysis to afford enantioenriched β,γ-diamino acid derived imidazolidin-2-ones as versatile chiral building blocks...
March 17, 2017: Organic Letters
Dagmar Hackenberger, Philip Weber, David C Blakemore, Lukas J Goossen
A decarboxylative cross-coupling of 3-substituted picolinic acids with (hetero)aryl halides is presented. In the presence of catalytic Cu2O and Pd(1,5-cyclooctadiene)Cl2 with 2-dicyclohexylphosphino-2'-(N,N-dimethylamino)biphenyl as the ligand, both electron-rich and electron-deficient aryl bromides and chlorides as well as heteroaryl bromides were successfully coupled with various picolinate salts under mild conditions in yields up to 96%. This protocol provides an efficient entry to 2-(hetero)arylpyridines, an attractive substance class in drug discovery...
March 16, 2017: Journal of Organic Chemistry
Fengbin Song, Rhys Salter, Lu Chen
Degradation-reconstruction approaches for isotope labeling synthesis have been known for their remarkable efficiency, but applications are scarce due to some fundamental limitations of the chemistries developed to date. The decarboxylative cyanation reaction, as a degradation-reconstruction approach, is especially useful in rapid carboxylic acid carbon isotope labeling, however development toward its application as a widespread technique has stalled at the early stages due to numerous limitations which include somewhat narrow applicability...
March 16, 2017: Journal of Organic Chemistry
Apiradee Pothipongsa, Saowarath Jantaro, Tiina A Salminen, Aran Incharoensakdi
Spermidine synthase (Spds) catalyzes the formation of spermidine by transferring the aminopropyl group from decarboxylated S-adenosylmethionine (dcSAM) to putrescine. The Synechococcus spds gene encoding Spds was expressed in Escherichia coli. The purified recombinant enzyme had a molecular mass of 33 kDa and showed optimal activity at pH 7.5, 37 °C. The enzyme had higher affinity for dcSAM (K m, 20 µM) than for putrescine (K m, 111 µM) and was highly specific towards the diamine putrescine with no activity observed towards longer chain diamines...
April 2017: World Journal of Microbiology & Biotechnology
Shima Tarahomi, Reza H Sajedi, Hossein Rahmani, Bijan Ranjbar, Majid Taghdir
Bioluminescence in Ca2+-binding photoproteins is an intramolecular reaction triggered by the addition of Ca2+. A comparative study has been done on Ca2+-depleted and Ca2+-loaded apo-mnemiopsin to understand the structural transition of the photoprotein by Ca2+ binding. Ca2+ is removed by TCA (trichloroacetic acid) precipitation to obtain Ca2+-depleted apo-mnemiopsin. UV-visible, CD and fluorescence spectroscopic studies demonstrate that the addition of Ca2+ is brought about by the overall structure of apo-mnemiopsin becomes more open in a concentration-dependent manner without significantly influencing the secondary structure and indicate that the Ca2+-depleted form of apo-mnemiopsin, in contrast to most other EF-hand calcium binding proteins, adopt a closed conformation when compared to the Ca2+-loaded form...
March 10, 2017: Protein and Peptide Letters
Xinqiang Tan, Tao Song, Zhentao Wang, He Chen, Lei Cui, Chaozhong Li
The silver-catalyzed Hunsdiecker bromination of aliphatic carboxylic acids is described. With Ag(Phen)2OTf as the catalyst and dibromoisocyanuric acid as the brominating agent, various aliphatic carboxylic acids underwent decarboxylative bromination to provide the corresponding alkyl bromides under mild conditions. This method not only is efficient and general but also enjoys wide functional group compatibility. An oxidative radical mechanism involving Ag(II) intermediates is proposed.
March 13, 2017: Organic Letters
Heike E Weber, Manuela Gottardi, Christine Brückner, Mislav Oreb, Eckhard Boles, Joanna Tripp
Biotechnological production of cis, cis-muconic acid from renewable feedstocks is an environmentally sustainable alternative to conventional, petroleum-based methods. Even though a heterologous production pathway for cis, cis-muconic acid has already been established in the host organism Saccharomyces cerevisiae, the generation of industrially relevant amounts of cis, cis-muconic acid is hampered by the low activity of the bacterial protocatechuic acid (PCA) decarboxylase AroY subunit C(iso) (AroY-C(iso)), leading to secretion of high amounts of the intermediate PCA to the medium...
March 10, 2017: Applied and Environmental Microbiology
Shu Cai, Li-Wei Chen, Yu-Chun Ai, Ji-Guo Qiu, Cheng-Hong Wang, Chao Shi, Jian He, Tian-Ming Cai
Sphingobium phenoxybenzoativorans SC_3 degrades and utilizes diphenyl ether (DE) and 2-carboxy DE as its sole carbon and energy source. In this study, we report the degradation of DE and 2-carboxy DE initiated by a novel ring-cleavage angular dioxygenase (Dpe) in the strain. Dpe functions at the angular carbon and its adjacent carbon (C1a, C2) of a benzene ring in DE (or the 2-carboxy benzene ring in 2-carboxy DE) and cleaves the C1a-C2 bond (decarboxylation is simultaneously happened for 2-carboxy DE), yielding 2,4-hexadienal phenyl ester, which is subsequently hydrolyzed to muconic acid semialdehyde and phenol...
March 10, 2017: Applied and Environmental Microbiology
Mathias Schäfer, Katrin Peckelsen, Mathias Paul, Jonathan Martens, Jos Oomens, Giel Berden, Albrecht Berkessel, Anthony J H M Meijer
While hydrogen tunneling at elevated temperatures has, for instance, often been postulated in biochemical processes, spectroscopic proof is thus far limited to cryogenic conditions, under which thermal reactivity is negligible. We report spectroscopic evidence for H-tunneling in the gas phase at temperatures around 320-350K observed in the isomerization reaction of a hydroxycarbene into an aldehyde. The charge-tagged carbene was generated in situ in a tandem mass spectrometer by decarboxylation of oxo[4-(trimethylammonio)phenyl]acetic acid upon collision induced dissociation...
March 10, 2017: Journal of the American Chemical Society
Jill A Caputo, Leah C Frenette, Norman Zhao, Kelly L Sowers, Todd D Krauss, Daniel J Weix
Photoredox catalysis has become an essential tool in organic synthesis because it enables new routes to important molecules. However, the best available molecular catalysts suffer from high catalyst loadings and rely on precious metals. Here we show that colloidal nanocrystal quantum dots (QDs) can serve as efficient and robust, precious-metal free, photoassisted redox catalysts. A single-sized CdSe quantum dot (3.0 ± 0.2 nm) can replace several different dye catalysts needed for five different photoredox reactions (β-alkylation, β-aminoalkylation, dehalogenation, amine arylation, and decarboxylative radical formation)...
March 10, 2017: Journal of the American Chemical Society
Wei Chen, Ruiqing Fan, Huijie Zhang, Yuwei Dong, Ping Wang, Yulin Yang
A series of lanthanide coordination polymers(LnCPs) containing both light and heavy rare-earth elements, namely {[Eu2(pydc)3(H2O)]·2H2O}n (1-Eu, H2pydc = pyridine-2,3-dicarboxylic acid), [Ln(pyc)2(Hpyc)(NO3)]n (Ln = Nd (2-Nd), Sm (3-Sm), Eu (4-Eu), Gd (5-Gd), Tb (6-Tb), Ho (7-Ho), and Er (8-Er), Hpyc = pyridine-3-carboxylic acid), has been synthesized under hydro(solvo)thermal conditions and fully characterized. The crystal structure analysis indicates that in situ decarboxylation of H2pydc occurred in the synthesis process of 2-Nd-8-Er...
March 10, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
Bo Fang, Huifang Xu, Yi Liu, Fengxia Qi, Wei Zhang, Hui Chen, Cong Wang, Yilin Wang, Wenxia Yang, Shengying Li
The cytochrome P450 enzyme OleTJE from Jeotgalicoccus sp. ATCC 8456 is capable of converting free long-chain fatty acids into α-alkenes via one-step oxidative decarboxylation in presence of H2O2 as cofactor or using redox partner systems. This enzyme has attracted much attention due to its intriguing but unclear catalytic mechanism and potential application in biofuel production. Here, we investigated the functionality of a select group of residues (Arg245, Cys365, His85, and Ile170) in the active site of OleTJE through extensive mutagenesis analysis...
March 9, 2017: Scientific Reports
Yuan Yuan, Adrienne Tarres, Thomas Bessaire, Richard H Stadler, Thierry Delatour
This study describes, for the first time, the role of pipecolic acid betaine and pipecolic acid, naturally present in some foods, in the formation of the plant growth regulator N,N-dimethylpiperidinium (mepiquat) under dry thermal conditions. The formation of mepiquat and intermediate compounds was investigated in model systems using high performance liquid chromatography-quadrupole/time-of-flight mass spectrometry. Mepiquat is released with a yield of up to 0.66mol% after thermal treatment (>150°C) of pipecolic acid betaine...
July 15, 2017: Food Chemistry
S Habran, T Desaive, Ph Morimont, B Lambermont, P C Dauby
Extracorporeal CO2 Removal device is used in clinics when a patient suffers from a pulmonary insufficiency like Acute Respiratory Distress Syndrome and allows to decarboxylate blood externally. In this work, a model of the respiratory system coupled with such a device is proposed to analyze the decrease of CO2 partial pressure in blood. To validate the model, some parameters are estimated thanks to experimental data. Metabolism is a crucial parameter and we show that its time evolution must be taken into account in order to have correct CO2 partial pressure simulations in arteries and in veins...
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
Ye Wei, Peng Hu, Min Zhang, Weiping Su
C-H bond activation and decarboxylation are two significant processes in organic synthesis. The combination of these processes provides a novel synthetic strategy, that is, decarboxylative C-H bond functionalization. Considerable attention has been focused on such an active research field. This review offers an overview of the utility of decarboxylative C-H bond functionalization in the synthesis of various organic compounds, such as styrenes, chalcones, biaryls, and heterocycles, covering most of the recent advances of the decarboxylative functionalization of Csp-H, Csp(2)-H, and Csp(3)-H bonds, as well as their scopes, limitations, practical applications, and synthetic potentials...
March 7, 2017: Chemical Reviews
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