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https://www.readbyqxmd.com/read/29345904/enzyme-initiated-quinone-chitosan-conjugation-chemistry-toward-a-general-in-situ-strategy-for-high-throughput-photoelectrochemical-enzymatic-bioanalysis
#1
Guang-Li Wang, Fang Yuan, Tiantian Gu, Yuming Dong, Qian Wang, Wei-Wei Zhao
Herein we report a general and novel strategy for high-throughput photoelectrochemical (PEC) enzymatic bioanalysis on the basis of enzyme-initiated quinone-chitosan conjugation chemistry (QCCC). Specifically, the strategy was illustrated by using a model quinones-generating oxidase of tyrosinase (Tyr) to catalytically produce 1,2-bezoquinone or its derivative, which can easily and selectively be conjugated onto the surface of the chitosan deposited PbS/NiO/FTO photocathode via the QCCC. Upon illumination, the covalently attached quinones could act as electron acceptors of PbS quantum dots (QDs), improving the photocurrent generation and thus allowing the elegant probing of Tyr activity...
January 18, 2018: Analytical Chemistry
https://www.readbyqxmd.com/read/29345430/wearable-wireless-tyrosinase-bandage-and-microneedle-sensors-toward-melanoma-screening
#2
Bianca Ciui, Aida Martin, Rupesh K Mishra, Barbara Brunetti, Tatsuo Nakagawa, Thomas J Dawkins, Mengjia Lyu, Cecilia Cristea, Robert Sandulescu, Joseph Wang
Wearable bendable bandage-based sensor and a minimally invasive microneedle biosensor are described toward rapid screening of skin melanoma. These wearable electrochemical sensors are capable of detecting the presence of the tyrosinase (TYR) enzyme cancer biomarker in the presence of its catechol substrate, immobilized on the transducer surface. In the presence of the surface TYR biomarker, the immobilized catechol is rapidly converted to benzoquinone that is detected amperometrically, with a current signal proportional to the TYR level...
January 18, 2018: Advanced Healthcare Materials
https://www.readbyqxmd.com/read/29341414/post-translational-incorporation-of-3-4-dihydroxyphenylalanine-into-the-c-terminus-of-%C3%AE-tubulin-in-living-cells
#3
Yanela M Dentesano, Yanina Ditamo, Cristian Hansen, Carlos A Arce, C Gastón Bisig
The C-terminal tyrosine (Tyr) of the α-tubulin chain is subjected to post-translational removal and re-addition in a process termed the "detyrosination/tyrosination cycle". We showed in previous studies using soluble rat brain extracts that L-3,4-dihydroxyphenylalanine (L-Dopa) is incorporated into the same site as Tyr. We now demonstrate that L-Dopa incorporation into tubulin also occurs in living cells. We detected such incorporation by determining the "tyrosination state" of tubulin before and after incubation of cells in the presence of L-Dopa...
January 17, 2018: FEBS Journal
https://www.readbyqxmd.com/read/29340478/the-long-and-successful-journey-of-electrochemically-active-amino-acids-from-fundamental-adsorption-studies-to-potential-surface-engineering-tools
#4
André H B Dourado, Fabián C Pastrián, Susana I Córdoba DE Torresi
Proteins have been the subject of electrochemical studies. It is possible to apply electrochemical techniques to obtain information about their structure due to the presence of five electroactive amino acids that can be oriented to the outside of the peptidic chain. These amino acids are L-Tryptophan (L-Trp), L-Tyrosine (L-Tyr), L-Histidine (L-His), L-Methionine (L-Met) and L-Cysteine (L-Cys); their electrochemical behavior being subject of extensive research, but it is still controversial. No spectroscopic investigations have been reported on L-Trp, and due to the short life time of the intermediates, ex situ techniques cannot be employed, leading to a never-ending discussion about possible intermediates...
January 11, 2018: Anais da Academia Brasileira de Ciências
https://www.readbyqxmd.com/read/29336997/modulation-of-nonessential-amino-acid-biosynthetic-pathways-in-virulent-hessian-fly-larvae-mayetiola-destructor-feeding-on-susceptible-host-wheat-triticum-aestivum
#5
Subhashree Subramanyam, Jacob T Shreve, Jill A Nemacheck, Alisha J Johnson, Brandi Schemerhorn, Richard H Shukle, Christie E Williams
Compatible interactions between wheat (Triticum aestivum), and its dipteran pest Hessian fly (Hf, Mayetiola destructor) result in successful establishment of larval feeding sites rendering the host plant susceptible. Virulent larvae employ an effector-based feeding strategy to reprogram the host physiology resulting in formation of a protein- and sugar-rich nutritive tissue beneficial to developing larvae. Previous studies documented increased levels of nonessential amino acids (NAA; that need not be received through insect diet) in the susceptible wheat in response to larval feeding, suggesting importance of plant-derived NAA in larval nutrition...
January 11, 2018: Journal of Insect Physiology
https://www.readbyqxmd.com/read/29336679/arcobacter-butzleri-ciprofloxacin-resistance-point-mutations-in-dna-gyrase-a-and-role-on-fitness-cost
#6
Susana Ferreira, Daniela R Correia, Mónica Oleastro, Fernanda C Domingues
Arcobacter butzleri is a widely distributed emerging pathogen resistant to various classes of antimicrobial agents, namely fluoroquinolones. A. butzleri resistance to fluoroquinolones is conferred by point mutations at the antibiotic target. The aim of this study was to evaluate mutations at gyrA associated with ciprofloxacin resistance and evaluate whether acquisition of resistance impacts on fitness and stress tolerance of A. butzleri. A. butzleri ciprofloxacin mutants were generated by laboratory induction...
January 16, 2018: Microbial Drug Resistance: MDR: Mechanisms, Epidemiology, and Disease
https://www.readbyqxmd.com/read/29336564/benzophenone-4-promotes-the-growth-of-a-pseudomonas-sp-and-biogenic-oxidation-of-mn-ii
#7
Yangyang Chang, Yaohui Bai, Yang Huo, Jiuhui Qu
Interactions between microbes and micropollutants (MPs) play a crucial role in water purification or treatment. Current studies have generally focused on the direct degradation or co-metabolism of MPs. Considering the increasing interest in and importance of the roles of MPs in microbial metabolism, we adopted a Mn(II)-oxidizing Pseudomonas sp. QJX-1 using tyrosine (Tyr) as the sole carbon and nitrogen source to investigate the effects of seven MPs on its growth and function. Six MPs exhibited an inhibition effect on bacterial growth and Mn(II) oxidation...
January 16, 2018: Environmental Science & Technology
https://www.readbyqxmd.com/read/29329864/antioxidant-and-anti-freezing-peptides-from-salmon-collagen-hydrolysate-prepared-by-bacterial-extracellular-protease
#8
RiBang Wu, CuiLing Wu, Dan Liu, XingHao Yang, JiaFeng Huang, Jiang Zhang, Binqiang Liao, HaiLun He
Extracted salmon skin collagen was hydrolysed with the free or immobilized extracellular protease of Vibrio sp. SQS2-3. The hydrolysate exhibited anti-freezing activity (>3 kDa) and antioxidant activity (<3000 Da) after ultrafiltration. The antioxidant peptide was further purified by size-exclusion chromatography and found to scavenge DPPH (73.29 ± 1.03%), OH (72.73 ± 3.34%,), and intracellular ROS in HUVECs; protect DNA against oxidation-induced damage; and have an ORAC of 2.78 ± 0...
May 15, 2018: Food Chemistry
https://www.readbyqxmd.com/read/29329856/effect-of-tyrosinase-aided-crosslinking-on-the-ige-binding-potential-and-conformational-structure-of-shrimp-metapenaeus-ensis-tropomyosin
#9
Ishfaq Ahmed, Liangtao Lv, Hong Lin, Zhenxing Li, Jiaju Ma, Chen Guanzhi, Lirui Sun, Lili Xu
The present study was performed to determine crosslinking and oxidative reactions catalyzed by tyrosinase (Tyr), caffeic acid (CA) and their combination with respect to IgE binding potential and conformational structure of shrimp tropomyosin (TM). Cross-links and IgE binding potentials were analyzed by SDS-PAGE, western blot and indirect ELISA. While structural changes were characterized using surface hydrophobicity, ultraviolet (UV), fluorescence and circular dichroism (CD) spectroscopies. Maximum reduction in the IgG (37...
May 15, 2018: Food Chemistry
https://www.readbyqxmd.com/read/29327587/conformational-impact-on-amino-acid-surface-%C3%AF-%C3%AF-interactions-on-a-7-7-single-walled-carbon-nanotube-a-molecular-mechanics-approach
#10
Linda Grabill, Andreas Riemann
A study of π-π interactions between a (7,7) single-walled carbon nanotube (SWNT) and three different aromatic amino acids (AAA), namely L-Tyrosine (Tyr), L-Tryptophan (Trp), and L-Phenylalanine (Phe) was conducted with a Molecular Mechanics (MM) approach. For each of the amino acids we investigated the behavior of six different conformers. We examined the impact of the so-called edge effects by testing the parameters of the built-in switching function in MM. We found the optimal SWNT length to be approximately 80Å for the size of the molecules in our conformational studies...
January 12, 2018: Journal of Physical Chemistry. A
https://www.readbyqxmd.com/read/29322836/activation-studies-with-amines-and-amino-acids-of-the-%C3%AE-carbonic-anhydrase-encoded-by-the-rv3273-gene-from-the-pathogenic-bacterium-mycobacterium-tuberculosis
#11
Andrea Angeli, Sonia Del Prete, Sameh M Osman, Fatmah A S Alasmary, Zeid AlOthman, William A Donald, Clemente Capasso, Claudiu T Supuran
The activation of a β-class carbonic anhydrase (CAs, EC 4.2.1.1) from Mycobacterium tuberculosis, encoded by the gene Rv3273 (mtCA 3), was investigated using a panel of natural and non-natural amino acids and amines. mtCA 3 was effectively activated by D-DOPA, L-Trp, dopamine and serotonin, with KAs ranging between 8.98 and 12.1 µM. L-His and D-Tyr showed medium potency activating effects, with KAs in the range of 17.6-18.2 µM, whereas other amines and amino acids were relatively ineffective activators, with KAs in the range of 28...
December 2018: Journal of Enzyme Inhibition and Medicinal Chemistry
https://www.readbyqxmd.com/read/29322229/bioanalytical-verification-of-v-type-nerve-agent-exposure-simultaneous-detection-of-phosphonylated-tyrosines-and-cysteine-containing-disulfide-adducts-derived-from-human-albumin
#12
Andreas Kranawetvogl, Jim Küppers, Markus Siegert, Michael Gütschow, Franz Worek, Horst Thiermann, Paul W Elsinghorst, Harald John
Nerve agents still represent a serious threat to civilian and military personnel as demonstrated by the violent conflict in the Middle East. For verification of poisoning, covalent adducts with endogenous proteins (e.g., human serum albumin, HSA) are valuable long-term biomarkers. Accordingly, we developed a microbore liquid chromatography-electrospray ionization mass spectrometry/high-resolution mass spectrometry (μLC-ESI MS/HR MS) method for simultaneous detection of HSA-adducts with the V-type nerve agents VX, Chinese VX (CVX), and Russian VX (RVX)...
January 10, 2018: Analytical and Bioanalytical Chemistry
https://www.readbyqxmd.com/read/29320928/interaction-of-caffeine-and-sulfadiazine-with-lysozyme-adsorbed-at-colloidal-metal-nanoparticle-interface-influence-on-drug-transport-ability-and-antibacterial-activity
#13
Vikash K Sonu, Imocha Rajkumar, Kaushik Bhattacharjee, S R Joshi, Sivaprasad Mitra
The modulated bioactivity of proteins immobilized on nanoparticle (NP) interfaces is of tremendous interest towards designing better therapeutic and diagnostic tools. In this work, binding behavior and the antibacterial activity of free lysozyme (LYS) as well as its non-covalent assembly with silver (Ag) and gold (Au) colloidal NPs were compared in presence of two model drugs, viz. sulfadiazine (SDZ) and caffeine (CAF). Intrinsic protein fluorescence was found to quench due to the formation drug-protein complex in case of CAF resulting a linear Stern-Volmer (SV) plot with KSV = 1...
January 11, 2018: Journal of Biomolecular Structure & Dynamics
https://www.readbyqxmd.com/read/29317025/electrochemical-sensing-platform-based-on-kelp-derived-hierarchical-meso-macroporous-carbons
#14
Yashuang Hei, Xiqian Li, Xiao Zhou, Jingju Liu, Mimi Sun, Tianze Sha, Cuixing Xu, Wanyi Xue, Xiangjie Bo, Ming Zhou
In this paper, kelp (Laminaria japonica), as a kind of abundant biomass, is used as the precursor for the preparation of kelp-derived hierarchical meso-macroporous carbons (K-dHMMCs) through the carbonization under nitrogen (N2) atmosphere at high temperature. The K-dHMMCs exhibits the unique structure with high specific surface area of 416.02 m2 g-1, large pore volume of 0.24 cm3 g-1, the hierarchical meso-macroporous size distribution centered at 2, 12 and 82 nm and high density of defective sites, enabling K-dHMMCs attractive for the electrocatalysis...
March 20, 2018: Analytica Chimica Acta
https://www.readbyqxmd.com/read/29316507/the-%C3%AE-carbonic-anhydrase-from-the-pathogenic-bacterium-vibrio-cholerae-is-potently-activated-by-amines-and-amino-acids
#15
Andrea Angeli, Sonia Del Prete, William A Donald, Clemente Capasso, Claudiu T Supuran
The γ-class carbonic anhydrase (CAs, EC 4.2.1.1) from the pathogenic bacterium Vibrio cholerae, VchCAγ, was investigated for its activation with a panel of natural and non-natural amino acids and amines. The enzyme was effectively activated by l-tryptophan, 1-(2-minoethyl)-piperazine and 4-(2-aminoethyl)-morpholine, in the low nanomolar range (KAs 8-71 nM). In contrast, l-/d-Phe, l-/d-DOPA, d-Trp, l-/d-Tyr, 4-amino-l-Phe, histamine, dopamine, serotonin, some pyridyl-alkylamines, as well as l-adrenaline were submicromolar activators (KAs between 0...
January 4, 2018: Bioorganic Chemistry
https://www.readbyqxmd.com/read/29315673/surveillance-for-antiviral-resistance-among-influenza-viruses-circulating-in-algeria-during-five-consecutive-influenza-seasons-2009-to-2014
#16
Assia Ait Aissa, Fawzi Derrar, Djouher Hanoun, El Alia Gradi, Dino Scaravelli, Zihad Bouslama
BACKGROUND: Influenza season 2007/2008 was marked by a worldwide emergence of oseltamivir-resistant A(H1N1) viruses possessing a mutation in the neuraminidase gene causing His-to-Tyr substitution at amino acid position 275 (H275Y). These strains were isolated in Algeria where 30% of seasonal A(H1N1) viruses harbored the H275Y mutation. Emergence of resistant viruses to currently approved antiviral drug determined the need for antiviral susceptibility monitoring in Algeria especially that oseltamivir is currently used in hospitals of some provinces of the country for treatment of influenza in populations at risk...
January 9, 2018: Journal of Medical Virology
https://www.readbyqxmd.com/read/29310310/l-tyrosine-polymerization-based-ultrasensitive-multi-analyte-enzymatic-biosensor
#17
Lanjunzi Liu, Xiuzhi Kang, Chao Chen, Heping Zhang, Chenpu Chen, Qingji Xie
Novel amperometric bi-enzyme biosensor based on tyrosinase (Tyr)-catalyzed L-tyrosine polymerization to effectively immobilize Tyr and glucose oxidase (GOx) simultaneously has been developed and is demonstrated to be efficient in monitoring multi-analyte (bisphenol A (BPA), phenol, Cr(III), glucose, and Cr(VI)). For the first time, the polymer from L-tyrosine oxidation (PLT) was utilized to in-situ immobilize biomacromolecules and was demonstrated to be effective in entrapping high-load and high-activity enzymes...
March 1, 2018: Talanta
https://www.readbyqxmd.com/read/29306981/unusual-stability-of-a-recombinant-verrucomicrobium-spinosum-tyrosinase-to-denaturing-agents-and-its-use-for-a-production-of-a-protein-with-adhesive-properties
#18
A S Axambayeva, L R Zhaparova, Zh S Shagyrova, E M Ramankulov, A V Shustov
Tyrosinases catalyze oxidation of phenols with a formation of biphenols, quinones, and highly polymerized melanins. Tyrosinases have prospects for industrial use to remove phenols, also in biosensors, in bioorganic synthesis, and for a production of biocompatible adhesives (medical glues). Despite growing fields of potential applications, a selection of commercially available tyrosinases are currently limited to a single enzyme which is isolated from fruiting bodies of mushrooms. This article describes a preparation of recombinant tyrosinase from a bacterium Verrucomicrobium spinosum using a heterologous expression in Escherichia coli...
January 6, 2018: Applied Biochemistry and Biotechnology
https://www.readbyqxmd.com/read/29305053/structure-kinetics-molecular-and-redox-properties-of-a-cytosolic-and-developmentally-regulated-fungal-catalase-peroxidase
#19
Vanessa Vega-García, Adelaida Díaz-Vilchis, Juan-Pablo Saucedo-Vázquez, Alejandro Solano-Peralta, Enrique Rudiño-Piñera, Wilhelm Hansberg
CAT-2, a cytosolic catalase-peroxidase (CP) from Neurospora crassa, which is induced during asexual spore formation, was heterologously expressed and characterized. CAT-2 had the Met-Tyr-Trp adduct required for catalase activity. Its KM for H2O2 was micromolar for peroxidase and millimolar for catalase activity. A Em = -158 mV reduction potential value was obtained and the Soret band shift suggested a mixture of low and high spin ferric iron. CAT-2 EPR spectrum at 10 K indicated an axial and a rhombic component...
January 2, 2018: Archives of Biochemistry and Biophysics
https://www.readbyqxmd.com/read/29304482/destabilization-of-ros-metabolism-in-tomato-roots-as-a-phytotoxic-effect-of-meta-tyrosine
#20
Olga Andrzejczak, Urszula Krasuska, Joanna Olechowicz, Paweł Staszek, Katarzyna Ciacka, Renata Bogatek, Kim Hebelstrup, Agnieszka Gniazdowska
meta-Tyrosine (m-Tyr) is a non-protein amino acid produced in both plants and animals. Primary mode of action of this phenylalanine analog is its incorporation into protein structure leading to formation of aberrant molecules. An increased level of m-Tyr in animal cells is detected under oxidative stress and during age-related processes characterized by overproduction of reactive oxygen species (ROS). The aim of this study was to link m-Tyr physiological action to disturbances in ROS metabolism in tomato (Solanum lycopersicum L...
December 14, 2017: Plant Physiology and Biochemistry: PPB
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