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https://www.readbyqxmd.com/read/29024806/dimerization-and-oxidation-of-tryptophan-in-uv-a-photolysis-sensitized-by-kynurenic-acid
#1
Ekaterina D Sormacheva, Peter S Sherin, Yuri P Tsentalovich
Photoinduced generation of radicals in the eye lens may play an important role in the modification of proteins, leading to their coloration, aggregation, and insolubilization. The radicals can be formed via the reactions of photoexcited endogenous chromophores of the human lens with lens proteins, in particular with tryptophan residues. In the present work we studied the reactions induced by UV-A (315-400nm) light between kynurenic acid (KNA), an effective photosensitizer present in the lens, and N-acetyl-L-tryptophan (NTrpH) under aerobic and anaerobic conditions...
October 9, 2017: Free Radical Biology & Medicine
https://www.readbyqxmd.com/read/28993242/a-distinct-microrna-expression-profile-is-associated-with-%C3%AE-11-c-methyl-l-tryptophan-amt-pet-uptake-in-epileptogenic-cortical-tubers-resected-from-patients-with-tuberous-sclerosis-complex
#2
Shruti Bagla, Daniela Cukovic, Eishi Asano, Sandeep Sood, Aimee Luat, Harry T Chugani, Diane C Chugani, Alan A Dombkowski
Tuberous sclerosis complex (TSC) is characterized by hamartomatous lesions in various organs and arises due to mutations in the TSC1 or TSC2 genes. TSC mutations lead to a range of neurological manifestations including epilepsy, cognitive impairment, autism spectrum disorders (ASD), and brain lesions that include cortical tubers. There is evidence that seizures arise at or near cortical tubers, but it is unknown why some tubers are epileptogenic while others are not. We have previously reported increased tryptophan metabolism measured with α[(11)C]-methyl-l-tryptophan (AMT) positron emission tomography (PET) in epileptogenic tubers in approximately two-thirds of patients with tuberous sclerosis and intractable epilepsy...
October 7, 2017: Neurobiology of Disease
https://www.readbyqxmd.com/read/28991984/role-of-dissolved-organic-matter-in-the-release-of-chromium-from-schwertmannite-kinetics-repartition-and-mechanisms
#3
Yingying Xie, Guining Lu, Han Ye, Chengfang Yang, Xiaoyun Yi, Zhi Dang
Dissolved organic matter (DOM) is an important factor influencing mineral biogeochemistry, although the role of labile DOM in the release of chromium (Cr) from schwertmannite, a mineral with high surface area, is unclear. In this study, the interaction of DOM with synthetic CrO-schwertmannite was investigated to better understand the potential fate of Cr in high-DOM environments. Minerals and their products were analyzed using Fourier transform infrared spectroscopy, X-ray diffraction, transmission electron microscopy, scanning electron microscopy, and X-ray photoelectron spectroscopy...
September 2017: Journal of Environmental Quality
https://www.readbyqxmd.com/read/28963347/evolution-of-allosteric-regulation-in%C3%A2-chorismate-mutases-from-early-plants
#4
Kourtney Kroll, Cynthia K Holland, Courtney M Starks, Joseph M Jez
Plants, fungi, and bacteria synthesize the aromatic amino acids:  L -phenylalanine,  L -tyrosine, and  L -tryptophan. Chorismate mutase catalyzes the branch point reaction of phenylalanine and tyrosine biosynthesis to generate prephenate. In  Arabidopsis thaliana , there are two plastid-localized chorismate mutases that are allosterically regulated (AtCM1 and AtCM3) and one cytosolic isoform (AtCM2) that is unregulated. Previous analysis of plant chorismate mutases suggested that the enzymes from early plants (i...
September 28, 2017: Biochemical Journal
https://www.readbyqxmd.com/read/28948133/high-yield-production-of-indole-3-acetic-acid-by-enterobacter-sp-dmku-rp206-a-rice-phyllosphere-bacterium-that-possesses-plant-growth-promoting-traits
#5
Pumin Nutaratat, Apitchaya Monprasit, Nantana Srisuk
Enterobacter sp. DMKU-RP206 was isolated from rice leaves in Thailand and identified by the 16S rRNA gene and multilocus sequence (gyrB, rpoB, atpD, and infB genes) analysis. The bacterium was assessed on plant growth-promoting traits including indole-3-acetic acid (IAA) production. Phosphate solubilization, ammonia production, and antagonism to fungal plant pathogens, as well as siderophore production, were shown by this bacterium. However, only IAA production was focused on. The production of IAA by Enterobacter sp...
October 2017: 3 Biotech
https://www.readbyqxmd.com/read/28931628/type-b-response-regulators-act-as-central-integrators-in-transcriptional-control-of-the-auxin-biosynthesis-enzyme-taa1
#6
Zhenwei Yan, Xin Liu, Karin Ljung, Shuning Li, Wanying Zhao, Fan Yang, Meiling Wang, Yi Tao
During embryogenesis and organ formation, establishing proper gradient is critical for auxin function, which is achieved through coordinated regulation of both auxin metabolism and transport. Expression of auxin biosynthetic genes is often tissue specific and is regulated by environmental signals. However, the underlying regulatory mechanisms remain elusive. Here, we investigated the transcriptional regulation of a key auxin biosynthetic gene, TAA1 (L-Tryptophan aminotransferase of Arabidopsis 1). A canonical and a novel ARR (Arabidopsis response regulators) binding site were identified in the promoter and the second intron of TAA1, which were required for its tissue specific expression...
September 20, 2017: Plant Physiology
https://www.readbyqxmd.com/read/28929575/development-of-an-optical-sensor-for-chlortetracycline-detection-based-on-the-fluorescence-quenching-of-l-tryptophan
#7
Hui Zhang, Hongyun Chen, Shuang Pan, Huan Yang, Jingjing Yan, Xiaoli Hu
A simple and selective spectrofluorimetric method for the detection of chlortetracycline (CTC) was studied. In pH 7.4 buffer medium l-tryptophan (l-Trp), applied as the fluorescence probe, interacted with CTC resulting in fluorescence quenching of the probe. CTC was detected with maximum excitation and emission wavelengths at λex /λem  = 275/350 nm. Notably, quenching of fluorescence intensities was positively proportional to the CTC concentration over the range of 0.65-30 μmol L(-1) and the limit of detection was 0...
September 20, 2017: Luminescence: the Journal of Biological and Chemical Luminescence
https://www.readbyqxmd.com/read/28926717/multiple-metabolic-pathways-for-metabolism-of-l-tryptophan-in-i-fusarium-graminearum-i
#8
Kun Luo, Caro-Lyne DesRoches, Anne Johnston, Linda J Harris, Hui-Yan Zhao, Thérèse Ouellet
<i>Fusarium graminearum </i>is a plant pathogen that can cause the devastating cereal grain disease fusarium head blight (FHB) in temperate regions of the world. Previous studies have shown that <i>F. graminearum </i>can synthetize indole-3-acetic acid (auxin) using L-tryptophan (L-TRP)-dependent pathways. In the present study, we have taken a broader approach to examine the metabolism of L-TRP in <i>F. graminearum </i>liquid culture. Our results showed that <i>F. graminearum </i>was able to transiently produce the indole tryptophol when supplied with L-TRP...
September 19, 2017: Canadian Journal of Microbiology
https://www.readbyqxmd.com/read/28900168/identification-of-key-metabolic-changes-during-liver-fibrosis-progression-in-rats-using-a-urine-and-serum-metabolomics-approach
#9
Hong Chang, Hong-Yu Meng, Shu-Min Liu, Yu Wang, Xiao-Xu Yang, Fang Lu, Hong-Yu Wang
Reversibility of hepatic fibrosis is an intrinsic response to chronic injury, and with on-going damage, fibrosis can progress to its end-stage consequence, cirrhosis. Non-invasive and reliable biomarkers for early detection of liver fibrosis are needed. Based on the CCl4-induced liver fibrosis rat model, urinary and serum metabolic profiling performed by LC-QTOF-MS associated with histological progression were utilized to identify liver fibrosis-specific potential biomarkers for early prediction and to reveal significant fibrotic pathways and their dynamic changes in different stages of liver fibrosis...
September 12, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28892124/systematic-optimization-of-l-tryptophan-riboswitches-for-efficient-monitoring-of-the-metabolite-in-escherichia-coli
#10
Sungho Jang, Gyoo Yeol Jung
Riboswitches form a class of genetically encoded sensor-regulators and are considered as promising tools for monitoring various metabolites. Functional parameters of a riboswitch, like dynamic or operational range, should be optimized before the riboswitch is implemented in a specific application for monitoring the target molecule efficiently. However, optimization of a riboswitch was not straightforward and required detailed studies owing to its complex sequence-function relationship. Here, we present three approaches for tuning and optimization of functional parameters of a riboswitch using an artificial L-tryptophan riboswitch as an example...
September 11, 2017: Biotechnology and Bioengineering
https://www.readbyqxmd.com/read/28884633/oxidative-removal-of-aromatic-amino-acids-by-manganese-dioxide-kinetic-modeling-and-effect-of-co-solutes
#11
Yong Chen, Jing Su, Lu Liu, Yiling Zhou, Jiaolan Zuo, Zongping Wang, Tao Tao
The degradation of aromatic amino acids including L-tryptophan, L-tyrosine and L-phenylalanine by δ-MnO2 was investigated. L-tryptophan and L-tyrosine underwent rapid oxidative degradation in the δ-MnO2 suspension solution. In contrast, L-phenylalanine was not oxidized by δ-MnO2. The degradation of L-tryptophan was faster than that of L-tyrosine. The oxidation rates of amino acids increased with increasing concentration of δ-MnO2. The increase of concentrations of substrates and pH disfavored the degradation...
September 8, 2017: Environmental Technology
https://www.readbyqxmd.com/read/28880969/anti-inflammatory-activities-of-garlic-sprouts-a-source-of-%C3%AE-linolenic-acid-and-5-hydroxy-l-tryptophan-in-raw-264-7-cells
#12
Joanna Gdula-Argasińska, Paweł Paśko, Katarzyna Sułkowska-Ziaja, Katarzyna Kała, Bożena Muszyńska
The purpose of this study was to analyze the indolic, phenolic, and fatty acid content and antioxidant activity of garlic sprouts growing in the dark and in the daylight. The pro- or anti-inflammatory properties of the garlic sprout extract were investigated by evaluating the cyclooxygenase-2 (COX-2), prostaglandin E synthase (cPGES), glutathione S transferase (GSTM1), nuclear factor NF-κB, peroxisome proliferator-activated receptors (PPARs), and aryl hydrocarbon receptor (AhR) protein levels in the RAW 264...
2017: Acta Biochimica Polonica
https://www.readbyqxmd.com/read/28841296/maltose-utilization-as-a-novel-selection-strategy-for-continuous-evolution-of-microbes-with-enhanced-metabolite-production
#13
Shu-De Liu, Yi-Nan Wu, Tian-Min Wang, Chong Zhang, Xin-Hui Xing
We have developed a novel selection circuit based on carbon source utilization that establishes and sustains growth-production coupling over several generations in a medium with maltose as the sole carbon source. In contrast to traditional antibiotic resistance-based circuits, we first proved that coupling of cell fitness to metabolite production by our circuit was more robust with a much lower escape risk even after many rounds of selection. We then applied the selection circuit to the optimization of L-tryptophan (l-Trp) production...
September 6, 2017: ACS Synthetic Biology
https://www.readbyqxmd.com/read/28820583/processing-2-methyl-l-tryptophan-through-tandem-transamination-and-selective-oxygenation-initiates-indole-ring-expansion-in-the-biosynthesis-of-thiostrepton
#14
Zhi Lin, Jia Ji, Shuaixiang Zhou, Fang Zhang, Jiequn Wu, Yinlong Guo, Wen Liu
Thiostrepton (TSR), an archetypal member of the family of ribosomally synthesized and post-translationally modified thiopeptide antibiotics, possesses a biologically important quinaldic acid (QA) moiety within the side-ring system of its characteristic thiopeptide framework. QA is derived from an independent l-Trp residue; however, its associated transformation process remains poorly understood. We here report that during the formation of QA, the key expansion of an indole to a quinoline relies on the activities of the pyridoxal-5'-phosphate-dependent protein TsrA and the flavoprotein TsrE...
August 23, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28809103/chiral-pedot-based-enantioselective-electrode-modification-material-for-chiral-electrochemical-sensing-mechanism-and-model-of-chiral-recognition
#15
Liqi Dong, Youshan Zhang, Xuemin Duan, Xiaofei Zhu, Hui Sun, Jingkun Xu
The development of electrochemical methods for enantioselective recognition is a focus of research in pharmaceuticals and biotechnology. In this study, a pair of water-soluble chiral 3,4-ethylenedioxythiophene (EDOT) derivatives, (R)-2'-hydroxymethyl-3,4-ethylenedioxythiophene ((R)-EDTM) and (S)-2'-hydroxymethyl-3,4-ethylenedioxythiophene ((S)-EDTM), were synthesized and electrodeposited on the surface of a glassy carbon electrode (GCE) via current-time (I-t) polymerization in an aqueous LiClO4 electrolyte...
August 25, 2017: Analytical Chemistry
https://www.readbyqxmd.com/read/28795267/cyp79-p450-monooxygenases-in-gymnosperms-cyp79a118-is-associated-with-the-formation-of-taxiphyllin-in-taxus-baccata
#16
Katrin Luck, Qidong Jia, Meret Huber, Vinzenz Handrick, Gane Ka-Shu Wong, David R Nelson, Feng Chen, Jonathan Gershenzon, Tobias G Köllner
Conifers contain P450 enzymes from the CYP79 family that are involved in cyanogenic glycoside biosynthesis. Cyanogenic glycosides are secondary plant compounds that are widespread in the plant kingdom. Their biosynthesis starts with the conversion of aromatic or aliphatic amino acids into their respective aldoximes, catalysed by N-hydroxylating cytochrome P450 monooxygenases (CYP) of the CYP79 family. While CYP79s are well known in angiosperms, their occurrence in gymnosperms and other plant divisions containing cyanogenic glycoside-producing plants has not been reported so far...
August 9, 2017: Plant Molecular Biology
https://www.readbyqxmd.com/read/28791767/the-delivery-of-doxorubicin-of-multifunctional-%C3%AE-cyclodextrin-modified-cdse-zns-quantum-dots-for-bioactivity-and-nano-probing
#17
Mei-Xia Zhao, Bing-Jie Zhu, Wen-Jing Yao, Di-Feng Chen, Chaojie Wang
The modified quantum dots (QDs), have been used in intracellular probing and drug delivery because of their special chemical and physical properties. In this paper, two β-cyclodextrin (β-CD)-modified CdSe/ZnS QDs with strong optical emission properties were synthesized as drug carriers to induce apoptosis. The positively charged L-Arginine (L-Arg) and neutral L-Tryptophan (L-Trp) were selected as ligands to compare the effect of charge on bioactivity of QDs nanoparticles. The in vitro assays revealed that these modified QDs showed good Dox carrier ability and significantly high inhibition rate to cancer cells...
August 9, 2017: Chemical Biology & Drug Design
https://www.readbyqxmd.com/read/28782925/adsorption-and-separation-of-aromatic-amino-acids-from-aqueous-solutions-using-metal-organic-frameworks
#18
Dries Jonckheere, Julian A Steele, Birgit Claes, Bart Bueken, Laurens Claes, Bert Lagrain, Maarten B J Roeffaers, Dirk E De Vos
Metal-organic frameworks (MOFs) are investigated for the adsorption of aromatic amino acids l-phenylalanine (l-Phe), l-tryptophan (l-Trp), and l-tyrosine (l-Tyr) from aqueous solutions. After screening a range of water-stable MOFs, the hydrophobic Zr-MOF MIL-140C emerged as the best performing material, exhibiting uptakes of 15 wt % for l-Trp and 20 wt % for l-Phe. These uptakes are 5-10 wt % higher than those of large-pore zeolites Beta and Y. Both single-compound and competitive adsorption isotherms for l-Phe and l-Trp were experimentally obtained at the natural pH of these amino acid mixtures (pH 6...
August 22, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28782794/overproduction-of-l-tryptophan-via-simultaneous-feed-of-glucose-and-anthranilic-acid-from-recombinant-e-coli-w3110-kinetic-modelling-and-process-scale-up
#19
Keju Jing, Yuanwei Tang, Chuanyi Yao, Ehecatl Antonio Del Rio-Chanona, Xueping Ling, Dongda Zhang
L-tryptophan is an essential amino acid widely used in food and pharmaceutical industries. However, its production via Escherichia coli fermentation suffers severely from both low glucose conversion efficiency and acetic acid inhibition, and to date effective process control methods have rarely been explored to facilitate its industrial scale production. To resolve these challenges, in the current research an engineered strain of Escherichia coli was used to overproduce L-tryptophan. To achieve this, a novel dynamic control strategy which incorporates an optimised anthranilic acid feeding into a dissolved oxygen-stat (DO-stat) glucose feeding framework was proposed for the first time...
August 7, 2017: Biotechnology and Bioengineering
https://www.readbyqxmd.com/read/28782636/embryo-yolk-sac-membrane-kynurenine-formamidase-of-l-tryptophan-to-nad-pathway-as-a-primary-target-for-organophosphorus-insecticides-opi-in-opi-induced-nad-associated-avian-teratogenesis
#20
Josef Seifert
The objective of this study was to provide in ovo evidence for the proposed role of kynurenine formamidase of l-tryptophan to NAD(+) pathway in embryo yolk sac membranes as a primary target for organophosphorus insecticide (OPI) teratogens in OPI-induced NAD-associated avian teratogenesis. Slices prepared from yolk sac membranes or embryo livers of chicken eggs treated with the OPI dicrotophos and/or methyl parathion were incubated with l-tryptophan. Yolk sac membrane slices metabolized l-tryptophan in the pathway to NAD(+) before that function was established in livers...
October 2017: Toxicology in Vitro: An International Journal Published in Association with BIBRA
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