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https://www.readbyqxmd.com/read/30172332/a-facile-avenue-to-prepare-chiral-graphene-sheets-as-electrode-modification-for-electrochemical-enantiorecognition
#1
Datong Wu, Wensheng Tan, Yin Yu, Baozhu Yang, Hongda Li, Yong Kong
Electrochemical enantiorecognition has attracted much interest due to its advantages of low cost and simple equipment. In this work, a new chiral ionic liquid is prepared and applied as an electrolyte for the one-step synthesis of functional graphene sheets (GO-(S,S)-CIL). More importantly, an electrode is modified by the material for the construction of an electrochemical sensor (GO-(S,S)-CIL-GCE). Enantiomers including L/D-tryptophan, (R)-/(S)-mandelic acid, (R)-/(S)-malic acid, and L/D-tyrosine are successfully distinguished by GO-(S,S)-CIL-GCE in the response of peak currents to different forms...
November 29, 2018: Analytica Chimica Acta
https://www.readbyqxmd.com/read/29977395/novel-unit-b-cryptophycin-analogues-as-payloads-for-targeted-therapy
#2
Eduard Figueras, Adina Borbély, Mohamed Ismail, Marcel Frese, Norbert Sewald
Cryptophycins are naturally occurring cytotoxins with great potential for chemotherapy. Since targeted therapy provides new perspectives for treatment of cancer, new potent analogues of cytotoxic agents containing functional groups for conjugation to homing devices are required. We describe the design, synthesis and biological evaluation of three new unit B cryptophycin analogues. The O -methyl group of the unit B D-tyrosine analogue was replaced by an O- (allyloxyethyl) moiety, an O- (hydroxyethyl) group, or an O- (((azidoethoxy)ethoxy)ethoyxethyl) substituent...
2018: Beilstein Journal of Organic Chemistry
https://www.readbyqxmd.com/read/29953888/the-dual-role-of-the-2-oh-group-of-a76-trna-tyr-in-the-prevention-of-d-tyrosine-mistranslation
#3
Mariia Yu Rybak, Oksana P Kovalenko, Michael A Tukalo
Aminoacyl-tRNA-synthetases are crucial enzymes for initiation step of translation. Possessing editing activity, they protect living cells from misincorporation of non-cognate and non-proteinogenic amino acids into proteins. Tyrosyl-tRNA synthetase (TyrRS) does not have such editing properties, but it shares weak stereospecificity in recognition of d-/l-tyrosine (Tyr). Nevertheless, an additional enzyme, d-aminoacyl-tRNA-deacylase (DTD), exists to overcome these deficiencies. The precise catalytic role of hydroxyl groups of the tRNATyr A76 in the catalysis by TyrRS and DTD remained unknown...
August 17, 2018: Journal of Molecular Biology
https://www.readbyqxmd.com/read/29885810/targeted-photodynamic-induced-singlet-oxygen-production-by-peptide-conjugated-biodegradable-nanoparticles-for-treatment-of-skin-melanoma
#4
Aya Ahmed Sebak, Iman Imam Gomaa, Aliaa Nabil ElMeshad, Mahmoud Hashem AbdelKader
BACKGROUND: Photodynamic therapy (PDT) has been determined to be a promising treatment modality in the most resistant tumors as malignant melanoma. Meanwhile, the key cytotoxic agent of PDT, -singlet oxygen (1 O2 ) - represents a high risk of photodynamic-associated side effects e.g. skin photosensitization. Recently, controllable photosensitization, where 1 O2 is produced on demand, has received increasing attention. In our study, this could be achieved via loading the photosensitizer (PS) in nanoparticles (NPs) decorated with target-specific moieties characterized by 1 O2 quenching abilities to specifically locate the PS in the targeted cells and assure that 1 O2 is only produced where desired after cellular processing...
June 7, 2018: Photodiagnosis and Photodynamic Therapy
https://www.readbyqxmd.com/read/29803076/brush-border-enzyme-cleavable-linkers-evaluation-for-reducing-renal-uptake-of-radiolabeled-prostate-specific-membrane-antigen-inhibitors
#5
Ganesan Vaidyanathan, Choong Mo Kang, Darryl McDougald, Il Minn, Mary Brummet, Martin G Pomper, Michael R Zalutsky
INTRODUCTION: Radiolabeled, low-molecular-weight prostate-specific membrane antigen (PSMA) inhibitors based on the Glu-ureido pharmacophore show promise for the detection and treatment of castration-resistant prostate cancer; however, high renal retention of activity, related in part to overexpression of PSMA in kidneys can be problematic. The goal of the current study was to investigate the use of brush border enzyme-cleavable linkers as a strategy for reducing kidney activity levels from radiolabeled PSMA inhibitors...
July 2018: Nuclear Medicine and Biology
https://www.readbyqxmd.com/read/29593796/application-of-d-amino-acids-as-biofilm-dispersing-agent-in-dental-unit-waterlines
#6
Ruchanee Salingcarnboriboon Ampornaramveth, Nilada Akeatichod, Jesita Lertnukkhid, Nichakorn Songsang
Aim and Purpose: Biofilms in dental unit waterlines (DUWLs) are extremely difficult to eliminate. Aim of this study is to evaluate the efficacy of a mixture of four D-amino acids on biofilm dispersion in DUWLs. Materials and Methods: A mixture of four D-amino acids (D-methionine, D-tryptophan, D-leucine, and D-tyrosine, 10 mM each), distilled water (control), and 0.1 M hydrochloric acid (HCl) was used in the experiment. In laboratory, pieces of DUWLs covered with biofilms were submerged in different solutions for 5 days, flushed, and measured OD600 of the dispersed biofilms...
2018: International Journal of Dentistry
https://www.readbyqxmd.com/read/29231751/activation-studies-of-the-%C3%AE-and-%C3%AE-carbonic-anhydrases-from-the-pathogenic-bacterium-vibrio-cholerae-with-amines-and-amino-acids
#7
Andrea Angeli, Sonia Del Prete, Sameh M Osman, Fatmah A S Alasmary, Zeid AlOthman, William A Donald, Clemente Capasso, Claudiu T Supuran
The α- and β-class carbonic anhydrases (CAs, EC 4.2.1.1) from the pathogenic bacterium Vibrio cholerae, VchCAα, and VchCAβ, were investigated for their activation with natural and non-natural amino acids and amines. The most effective VchCAα activators were L-tyrosine, histamine, serotonin, and 4-aminoethyl-morpholine, which had KA s in the range of 8.21-12.0 µM. The most effective VchCAβ activators were D-tyrosine, dopamine, serotonin, 2-pyridyl-methylamine, 2-aminoethylpyridine, and 2-aminoethylpiperazine, which had KA s in the submicromolar - low micromolar range (0...
December 2018: Journal of Enzyme Inhibition and Medicinal Chemistry
https://www.readbyqxmd.com/read/29208656/pvdo-is-required-for-the-oxidation-of-dihydropyoverdine-as-the-last-step-of-fluorophore-formation-in-pseudomonas-fluorescens
#8
Michael T Ringel, Gerald Dräger, Thomas Brüser
Pyoverdines are important siderophores that guarantee iron supply to important pathogenic and non-pathogenic pseudomonads in host habitats. A key characteristic of all pyoverdines is the fluorescent dihydroxyquinoline group that contributes two ligands to the iron complexes. Pyoverdines are derived from the non-ribosomally synthesized peptide ferribactin, and their fluorophore is generated by periplasmic oxidation and cyclization reactions of d-tyrosine and l-diaminobutyric acid. The formation of the fluorophore is known to be driven by the periplasmic tyrosinase PvdP...
February 16, 2018: Journal of Biological Chemistry
https://www.readbyqxmd.com/read/29202342/d-tyrosine-loaded-nanocomposite-membranes-for-environmental-friendly-long-term-biofouling-control
#9
Cong Yu, Jinjian Wu, Gilherme Zin, Marco Di Luccio, Donghui Wen, Qilin Li
Strategies to control biofouling without using antimicrobial chemicals are needed to prevent the spread of antibiotic resistance genes and disruption of microbial activities in biological treatment. This study developed an environmentally friendly biofouling resistant membrane by incorporating d-tyrosine onto a commercial nanofiltration membrane using FAU type zeolite nanoparticles that covalently bound to the membrane surface as carriers for slow release. The d-tyrosine loaded membrane had similar water permeability as the unmodified membrane, but greatly reduced initial cell attachment and strongly inhibited subsequent biofilm formation without inactivating the bacteria...
March 1, 2018: Water Research
https://www.readbyqxmd.com/read/29197276/one-pot-radiosynthesis-of-o-18-f-fluoromethyl-d-tyrosine-via-intra-molecular-nucleophilic-18-f-fluorination-with-1-2-3-triazolium-triflate-salt-precursor
#10
Ho Young Kim, Chansoo Park, Ji Youn Lee, Dae Yoon Chi, Yun-Sang Lee, Jae Min Jeong
A radiolabeled amino acid O-[18 F]fluoromethyl-D-tyrosine (D-[18 F]FMT) has been reported to show high tumor uptake. However, introduction of [18 F]fluoromethyl group was difficult and was an issue to be solved. We solved it by using a precursor containing 1,2,3-triazolium salt. D-[18 F]FMT was synthesized from (R)-1-((4-(2-((tert-butoxycarbonyl)amino)-3-((3,4-dimethylbenzyl)oxy)-3-oxopropyl)phenoxy)methyl)-3-methyl-4-phenyl-1H-1,2,3-triazol-3-ium trifluoromethanesulfonate via intra-molecular 18 F-fluorination and subsequent removal of the protecting groups...
February 2018: Applied Radiation and Isotopes
https://www.readbyqxmd.com/read/29121440/d-tyrosine-negatively-regulates-melanin-synthesis-by-competitively-inhibiting-tyrosinase-activity
#11
Jisu Park, Hyejung Jung, Kyuri Kim, Kyung-Min Lim, Ji-Young Kim, Eek-Hoon Jho, Eok-Soo Oh
Although L-tyrosine is well known for its melanogenic effect, the contribution of D-tyrosine to melanin synthesis was previously unexplored. Here, we reveal that, unlike L-tyrosine, D-tyrosine dose-dependently reduced the melanin contents of human MNT-1 melanoma cells and primary human melanocytes. In addition, 500 μM of D-tyrosine completely inhibited 10 μM L-tyrosine-induced melanogenesis, and both in vitro assays and L-DOPA staining MNT-1 cells showed that tyrosinase activity is reduced by D-tyrosine treatment...
May 2018: Pigment Cell & Melanoma Research
https://www.readbyqxmd.com/read/28861053/enhanced-biocide-treatments-with-d-amino-acid-mixtures-against-a-biofilm-consortium-from-a-water-cooling-tower
#12
Ru Jia, Yingchao Li, Hussain H Al-Mahamedh, Tingyue Gu
Different species of microbes form mixed-culture biofilms in cooling water systems. They cause microbiologically influenced corrosion (MIC) and biofouling, leading to increased operational and maintenance costs. In this work, two D-amino acid mixtures were found to enhance two non-oxidizing biocides [tetrakis hydroxymethyl phosphonium sulfate (THPS) and NALCO 7330 (isothiazoline derivatives)] and one oxidizing biocide [bleach (NaClO)] against a biofilm consortium from a water cooling tower in lab tests. Fifty ppm (w/w) of an equimass mixture of D-methionine, D-leucine, D-tyrosine, D-tryptophan, D-serine, D-threonine, D-phenylalanine, and D-valine (D8) enhanced 15 ppm THPS and 15 ppm NALCO 7330 with similar efficacies achieved by the 30 ppm THPS alone treatment and the 30 ppm NALCO 7330 alone treatment, respectively in the single-batch 3-h biofilm removal test...
2017: Frontiers in Microbiology
https://www.readbyqxmd.com/read/28761161/mitigation-of-a-nitrate-reducing-pseudomonas-aeruginosa-biofilm-and-anaerobic-biocorrosion-using-ciprofloxacin-enhanced-by-d-tyrosine
#13
Ru Jia, Dongqing Yang, Dake Xu, Tingyue Gu
Pseudomonas aeruginosa (PA) is a ubiquitous microbe. It can form recalcitrant biofilms in clinical and industrial settings. PA biofilms cause infections in patients. They also cause biocorrosion of medical implants. In this work, D-tyrosine (D-tyr) was investigated as an antimicrobial enhancer for ciprofloxacin (CIP) against a wild-type PA biofilm (strain PAO1) on C1018 carbon steel in a strictly anaerobic condition. Seven-day biofilm prevention test results demonstrated that 2 ppm (w/w) D-tyr enhanced 30 ppm CIP by achieving extra 2-log sessile cell reduction compared with the 30 ppm CIP alone treatment...
July 31, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28286870/d-amino-acids-do-not-inhibit-pseudomonas-aeruginosa-biofilm-formation
#14
Wee Tin K Kao, Mitchell Frye, Patricia Gagnon, Joseph P Vogel, Richard Chole
OBJECTIVE: Pseudomonas aeruginosa , a known biofilm-forming organism, is an opportunistic pathogen that plays an important role in chronic otitis media, tracheitis, cholesteatoma, chronic wounds, and implant infections. Eradication of biofilm infections has been a challenge because the biofilm phenotype provides bacteria with a protective environment from the immune system and antibiotics; thus, there has been great interest in adjunctive molecules that may inhibit biofilm formation or cause biofilm dispersal...
February 2017: Laryngoscope Investigative Otolaryngology
https://www.readbyqxmd.com/read/28271098/a-dinuclear-biomimetic-cu-complex-derived-from-l-histidine-synthesis-and-stereoselective-oxidations
#15
Maria L Perrone, Elena Salvadeo, Eliana Lo Presti, Luca Pasotti, Enrico Monzani, Laura Santagostini, Luigi Casella
A dinuclear copper(ii) complex derived from the chiral N6 ligand (2S,2'S)-N,N'-(ethane-1,2-diyl)bis(2-((1-methyl-1H-imidazol-4-ylmethyl)-amino)-3-(1-trityl-1H-imidazol-4-yl)propanamide) (EHI) was synthesized and studied as a catalyst in stereoselective oxidation reactions. The ligand contains two sets of tridentate binding units, each of them giving rise to a coordination set consisting of a pair of 5- and 6-membered chelate rings, connected by an ethanediamide linker. Stereoselectivity effects were studied in the oxidations of a series of chiral l/d biogenic catechols and the pair of l/d-tyrosine methyl esters, in this case as their phenolate salts...
March 21, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
https://www.readbyqxmd.com/read/28151960/d-amino-acids-reduce-enterococcus-faecalis-biofilms-in-vitro-and-in-the-presence-of-antimicrobials-used-for-root-canal-treatment
#16
Peter S Zilm, Victor Butnejski, Giampiero Rossi-Fedele, Stephen P Kidd, Suzanne Edwards, Krasimir Vasilev
Enterococcus faecalis is the most frequent species present in post-treatment disease and plays a significant role in persistent periapical infections following root canal treatment. Its ability to persist in stressful environments is inter alia, due to its ability to form biofilms. The presence of certain D-amino acids (DAAs) has previously been shown to reduce formation of Bacillus subtilis biofilms. The aims of this investigation were to determine if DAAs disrupt biofilms in early and late growth stages for clinical E...
2017: PloS One
https://www.readbyqxmd.com/read/27780756/spectrophotometric-assays-for-monitoring-trna-aminoacylation-and-aminoacyl-trna-hydrolysis-reactions
#17
REVIEW
Eric A First, Charles J Richardson
Aminoacyl-tRNA synthetases play a central role in protein synthesis, catalyzing the attachment of amino acids to their cognate tRNAs. Here, we describe a spectrophotometric assay for tyrosyl-tRNA synthetase in which the Tyr-tRNA product is cleaved, regenerating the tRNA substrate. As tRNA is the limiting substrate in the assay, recycling it substantially increases the sensitivity of the assay while simultaneously reducing its cost. The tRNA aminoacylation reaction is monitored spectrophotometrically by coupling the production of AMP to the conversion of NAD+ to NADH...
January 15, 2017: Methods: a Companion to Methods in Enzymology
https://www.readbyqxmd.com/read/27716985/d-tyrosine-affects-aggregation-behavior-of-pantoea-agglomerans
#18
Jing Yang, Jiajia Yu, Jing Jiang, Chen Liang, Yongjun Feng
D-amino acids have been proved to disassemble biofilms by disassociating the matrix. Pantoea agglomerans is characterized by the formation of another kind of multicellular structure called symplasmata, which also remains the ability to form biofilms. In this study, a rice diazotrophic endophyte P. agglomerans YS19 was selected as a model strain to explore the effects of D-amino acids on these two kinds of cell aggregate structures. It was discovered that D-tyrosine disassociates biofilm, yet promotes symplasmata formation...
February 2017: Journal of Basic Microbiology
https://www.readbyqxmd.com/read/27379039/enhanced-biocide-mitigation-of-field-biofilm-consortia-by-a-mixture-of-d-amino-acids
#19
Yingchao Li, Ru Jia, Hussain H Al-Mahamedh, Dake Xu, Tingyue Gu
Microbiologically influenced corrosion (MIC) is a major problem in the oil and gas industry as well as in many other industries. Current treatment methods rely mostly on pigging and biocide dosing. Biocide resistance is a growing concern. Thus, it is desirable to use biocide enhancers to improve the efficacy of existing biocides. D-Amino acids are naturally occurring. Our previous work demonstrated that some D-amino acids are biocide enhancers. Under a biocide stress of 50 ppm (w/w) hydroxymethyl phosphonium sulfate (THPS) biocide, 1 ppm D-tyrosine and 100 ppm D-methionine used separately successfully mitigated the Desulfovibrio vulgaris biofilm on carbon steel coupons...
2016: Frontiers in Microbiology
https://www.readbyqxmd.com/read/27064538/hyperactive-editing-domain-variants-switch-the-stereospecificity-of-tyrosyl-trna-synthetase
#20
Charles J Richardson, Eric A First
d-Amino acids are excluded at three different steps during protein synthesis: the aminoacylation of tRNA, binding of aminoacyl-tRNAs to EF-Tu, and selection of the aminoacyl-tRNA by the ribosome. We previously altered the enantioselectivity of tyrosyl-tRNA synthetase (TyrRS) by inserting the editing domain from phenylalanyl-tRNA synthetase (FRSed) between Gly 161 and Ile 162 in tyrosyl-tRNA synthetase (the editing domain hydrolyzes l-Tyr-tRNA but not d-Tyr-tRNA). In this paper, we test the hypothesis that the enantioselectivity of this TyrRS-FRSed chimera can be shifted further toward the formation of d-Tyr-tRNA by introducing activating mutations into the editing site...
May 3, 2016: Biochemistry
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