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Enzyme kinetics

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https://www.readbyqxmd.com/read/28813027/sulfonamide-linked-ciprofloxacin-sulfadiazine-and-amantadine-derivatives-as-a-novel-class-of-inhibitors-of-jack-bean-urease-synthesis-kinetic-mechanism-and-molecular-docking
#1
Pervaiz Ali Channar, Aamer Saeed, Fernando Albericio, Fayaz Ali Larik, Qamar Abbas, Mubashir Hassan, Hussain Raza, Sung-Yum Seo
Sulfonamide derivatives serve as an important building blocks in the drug design discovery and development (4D) process. Ciprofloxacin-, sulfadiazine- and amantadine-based sulfonamides were synthesized as potent inhibitors of jack bean urease and free radical scavengers. Molecular diversity was explored and electronic factors were also examined. All 24 synthesized compounds exhibited excellent potential against urease enzyme. Compound 3e (IC50 = 0.081 ± 0.003 µM), 6a (IC50 = 0.0022 ± 0.0002 µM), 9e (IC50 = 0...
August 16, 2017: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
https://www.readbyqxmd.com/read/28812762/a-facile-synthesis-of-cufe2o4-cu9s8-ppy-ternary-nanotubes-as-peroxidase-mimics-for-the-sensitive-colorimetric-detection-of-h2o2-and-dopamine
#2
Zezhou Yang, Fuqiu Ma, Yun Zhu, Sihui Chen, Ce Wang, Xiaofeng Lu
Synergistic effects play an important role in improving the catalytic activity for enzyme-like reactions. Compared to individual nanomaterials, a system consisting of multiple components usually exhibits enhanced catalytic activity as an enzyme mimic. Herein we describe the synthesis of CuFe2O4/Cu9S8/polypyrrole (PPy) ternary nanotubes as an efficient peroxidase mimic via a three-step approach involving an electrospinning process, annealing treatment and hydrothermal reaction. The remarkably enhanced catalytic activity of CuFe2O4/Cu9S8/PPy ternary nanotubes as peroxidase mimics over individual CuFe2O4 nanofibers, CuFe2O4/CuO composite nanofibers, CuFe2O4/CuS composite nanofibers, and PPy materials has been achieved, demonstrating the presence of a synergistic effect among the components...
August 16, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
https://www.readbyqxmd.com/read/28811708/involvement-of-crf2-signaling-in-enterocyte-differentiation
#3
Benjamin Ducarouge, Marjolaine Pelissier-Rota, Rebecca Powell, Alain Buisson, Bruno Bonaz, Muriel Jacquier-Sarlin
AIM: To determine the role of corticotropin releasing factor receptor (CRF2) in epithelial permeability and enterocyte cell differentiation. METHODS: For this purpose, we used rat Sprague Dawley and various colon carcinoma cell lines (SW620, HCT8R, HT-29 and Caco-2 cell lines). Expression of CRF2 protein was analyzed by fluorescent immunolabeling in normal rat colon and then by western blot in dissociated colonic epithelial cells and in the lysates of colon carcinoma cell lines or during the early differentiation of HT-29 cells (ten first days)...
July 28, 2017: World Journal of Gastroenterology: WJG
https://www.readbyqxmd.com/read/28811265/molecular-cloning-heterologous-expression-and-functional-characterization-of-gamma-tocopherol-methyl-transferase-%C3%AE-tmt-from-glycine-max
#4
Kalpana Tewari, Anil Dahuja, Archana Sachdev, Kishwar Ali, Vaibhav Kumar, Amresh Kumar, Sweta Kumari
γ-Tocopherol methyltransferase (γ-TMT) (EC 2.1.1.95) is the last enzyme in the tocopherol biosynthetic pathway and it catalyzes the conversion of γ-tocopherol into α-tocopherol, the nutritionally significant and most bioactive form of vitamin E. Although the γ-TMT gene has been successfully overexpressed in many crops to enhance their α-tocopherol content but still only few attempts have been made to uncover its structural, functional and regulation aspects at protein level. In this study, we have cloned the complete 909bp coding sequence of Glycine max γ-TMT (Gm γ-TMT) gene that encodes the corresponding protein comprising of 302 amino acid residues...
August 12, 2017: Protein Expression and Purification
https://www.readbyqxmd.com/read/28809841/measuring-neuromuscular-junction-functionality
#5
Emanuele Rizzuto, Simona Pisu, Carmine Nicoletti, Zaccaria Del Prete, Antonio Musarò
Neuromuscular junction (NMJ) functionality plays a pivotal role when studying diseases in which the communication between motor neuron and muscle is impaired, such as aging and amyotrophic lateral sclerosis (ALS). Here we describe an experimental protocol that can be used to measure NMJ functionality by combining two types of electrical stimulation: direct muscle membrane stimulation and the stimulation through the nerve. The comparison of the muscle response to these two different stimulations can help to define, at the functional level, potential alterations in the NMJ that lead to functional decline in muscle...
August 6, 2017: Journal of Visualized Experiments: JoVE
https://www.readbyqxmd.com/read/28809813/molecular-mechanisms-underlying-inhibitory-binding-of-alkylimidazolium-ionic-liquids-to-laccase
#6
Jianliang Sun, Hao Liu, Wenping Yang, Shicheng Chen, Shiyu Fu
Water-miscible alkylimidazolium ionic liquids (ILs) are "green" co-solvents for laccase catalysis, but generally inhibit enzyme activity. Here, we present novel insights into inhibition mechanisms by a combination of enzyme kinetics analysis and molecular simulation. Alkylimidazolium cations competitively bound to the TI Cu active pocket in the laccase through hydrophobic interactions. Cations with shorter alkyl chains (C₂~C₆) entered the channel inside the pocket, exhibiting a high compatibility with laccase (competitive inhibition constant Kic = 3...
August 15, 2017: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
https://www.readbyqxmd.com/read/28809002/probing-protein-kinase-atp-interactions-using-a-fluorescent-atp-analog
#7
Leslie E W LaConte, Sarika Srivastava, Konark Mukherjee
Eukaryotic protein kinases are an intensely investigated class of enzymes which have garnered attention due to their usefulness as drug targets. Determining the regulation of ATP binding to a protein kinase is not only critical for understanding function in a cellular context but also for designing kinase-specific molecular inhibitors. Here, we provide a general procedure for characterizing ATP binding to eukaryotic protein kinases. The protocol can be adapted to identify the conditions under which a particular kinase is activated...
2017: Methods in Molecular Biology
https://www.readbyqxmd.com/read/28808704/enzymatic-activity-inside-a-dna-peptide-complex
#8
Wei Pan, Hao Wen, Dehai Liang
The mutual interaction between enzymes and their environments plays a key role in various life processes. In this study, using the complexes formed by salmon DNA and a de novo designed peptide, Ac-RRRRRRRRRGALGLPGKGGGLQRLTALDGR-NH2 (abbreviated as RR-30), as a model, we studied the activity of collagenase encapsulated inside the complex. Collagenase is able to cleave RR-30 at a LG/LP site, generating two shorter length peptides, which decreases the stability of the complex. Results show that the complex dissociates with time in the presence of collagenase...
August 15, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28808005/conformational-dynamics-of-1-deoxy-d-xylulose-5-phosphate-synthase-on-ligand-binding-revealed-by-h-d-exchange-ms
#9
Jieyu Zhou, Luying Yang, Alicia DeColli, Caren Freel Meyers, Natalia S Nemeria, Frank Jordan
The enzyme 1-deoxy-d-xylulose 5-phosphate synthase (DXPS) is a key enzyme in the methylerythritol 4-phosphate pathway and is a target for the development of antibiotics, herbicides, and antimalarial drugs. DXPS catalyzes the formation of 1-deoxy-d-xylulose 5-phosphate (DXP), a branch point metabolite in isoprenoid biosynthesis, and is also used in the biosynthesis of thiamin (vitamin B1) and pyridoxal (vitamin B6). Previously, we found that DXPS is unique among the superfamily of thiamin diphosphate (ThDP)-dependent enzymes in stabilizing the predecarboxylation intermediate, C2-alpha-lactyl-thiamin diphosphate (LThDP), which has subsequent decarboxylation that is triggered by d-glyceraldehyde 3-phosphate (GAP)...
August 14, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28807908/activity-of-the-%C3%AE-lactamase-inhibitor-ln-1-255-against-carbapenem-hydrolyzing-class-d-%C3%AE-lactamases-from-acinetobacter-baumannii
#10
Juan Carlos Vázquez-Ucha, María Maneiro, Marta Martínez-Guitián, John Buynak, Christopher R Bethel, Robert A Bonomo, Germán Bou, Margarita Poza, Concepción González-Bello, Alejandro Beceiro
The number of infections caused by Gram-negative pathogens carrying carbapenemases is increasing, and the group of carbapenem-hydrolyzing class D β-lactamases (CHDLs) is especially problematic. Several clinically important CHDLs have been identified in A. baumannii, including OXA-23, OXA-24/40, OXA-58, OXA-143, OXA-235, and the chromosomally encoded OXA-51. The selection and dissemination of carbapenem-resistant A. baumannii strains constitutes a serious global threat. Carbapenems have been successfully utilized as last resort antibiotics for the treatment of multi-drug-resistant A...
August 14, 2017: Antimicrobial Agents and Chemotherapy
https://www.readbyqxmd.com/read/28807888/spectroscopic-and-calorimetric-assays-reveal-dependence-on-dctp-and-two-metals-zn-2-mg-2-for-enzymatic-activity-of-schistosoma-mansoni-deoxycytidylate-dcmp-deaminase
#11
Jéssica Fernandes Scortecci, Vitor Hugo Balasco Serrão, Juliana Cheleski, Juliana Roberta Torini, Larissa Romanello, Ricardo DeMarco, Humberto D'Muniz Pereira
The parasite Schistosoma mansoni possess all pathways for pyrimidine biosynthesis, whereby deaminases play an essential role in the thymidylate cycle, a crucial step to controlling the ratio between cytidine and uridine nucleotides. In this study, we heterologously expressed and purified the deoxycytidylate (dCMP) deaminase from S. mansoni to obtain structural, biochemical and kinetic information. Small-angle X-ray scattering of this enzyme showed that it is organized as a hexamer in solution. Isothermal titration calorimetry was used to determine the kinetic constants for dCMP-dUMP conversion and the role of dCTP and dTTP in enzymatic regulation...
August 11, 2017: Biochimica et Biophysica Acta
https://www.readbyqxmd.com/read/28807679/identification-and-characterization-of-5%C3%AE-cyprinol-sulfating-cytosolic-sulfotransferases-sults-in-the-zebrafish-danio-rerio
#12
Katsuhisa Kurogi, Maki Yoshihama, Austin Horton, Isaac T Schiefer, Matthew D Krasowski, Lee R Hagey, Frederick E Williams, Yoichi Sakakibara, Naoya Kenmochi, Masahito Suiko, Ming-Cheh Liu
5α-Cyprinol 27-sulfate is the major biliary bile salt present in cypriniform fish including the zebrafish (Danio rerio). The current study was designed to identify the zebrafish cytosolic sulfotransferase (Sult) enzyme(s) capable of sulfating 5α-cyprinol and to characterize the zebrafish 5α-cyprinol-sulfating Sults in comparison with human SULT2A1. Enzymatic assays using zebrafish homogenates showed 5α-cyprinol-sulfating activity. A systematic analysis, using a panel of recombinant zebrafish Sults, revealed two Sult2 subfamily members, Sult2st2 and Sult2st3, as major 5α-cyprinol-sulfating Sults...
August 11, 2017: Journal of Steroid Biochemistry and Molecular Biology
https://www.readbyqxmd.com/read/28806521/determination-of-caspase-3-activity-and-its-inhibition-constant-by-combination-of-fluorescence-correlation-spectroscopy-with-a-microwell-chip
#13
Di Su, Xiaocai Hu, Chaoqing Dong, Jicun Ren
Caspase-3 is a key enzyme executing apoptosis during ontogenesis and homeostasis of multicellular organisms, and is a very important and potential drug target in treatment of apoptosis disturbance. So far, no commercial drugs for caspase-3 are available, and it is urgently necessitated to develop an effective method for caspase-3 activity assay and its inhibitor screening. In this paper, we propose a new method for determination of caspase-3 activity and its inhibition constant by combining single molecule fluorescence correlation spectroscopy (FCS) with a microwell chip...
August 14, 2017: Analytical Chemistry
https://www.readbyqxmd.com/read/28806505/co4n-nanowires-noble-metal-free-peroxidase-mimetic-with-excellent-salt-and-temperature-resistant-abilities
#14
Yu-Zhen Li, Tong-Tong Li, Wei Chen, Yan-Yan Song
Compared to natural enzymes, nanomaterial-based artificial enzymes have attracted immense attention because of their high stability and cost-effectiveness. In this study, cobalt nitride (Co4N) as a noble-metal-free artificial enzyme exhibiting highly intrinsic peroxidase-like activity and good stability was reported. Kinetic studies revealed that the resultant Co4N nanowires (NWs) exhibited a stronger affinity for 3,3',5,5'-tetramethylbenzidine (TMB) and H2O2 than HRP. Compared to Co3O4 NWs, Co4N NWs exhibited highly improved catalytic activities, with H2O2 exhibiting an apparent Km approximately 2 orders of magnitude less than that of Co3O4...
August 14, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28805981/noncompetitive-inhibition-of-human-cyp2c9-in%C3%A2-vitro-by-a-commercial-rhodiola-rosea-product
#15
Ole Kristian Forstrønen Thu, Olav Spigset, Bent Hellum
A commercial Rhodiola rosea (R. rosea) product has previously demonstrated CYP2C9 inhibition in humans. The purpose of this study was to provide in vitro inhibitory data for this particular interaction and to classify the mechanism of the interaction. Another aim was to examine the in vitro influence of ethanol on the CYP2C9 activity. Human CYP2C9 (wild type) isolated from a baculovirus-infected cell system was incubated with 0.8 μmol/L losartan for 20 min. Sulfaphenazole was used as a positive control...
August 2017: Pharmacology Research & Perspectives
https://www.readbyqxmd.com/read/28805378/in-vitro-modulation-of-renin-angiotensin-system-enzymes-by-amaranth-amaranthus-hypochondriacus-protein-derived-peptides-alternative-mechanisms-different-from-ace-inhibition
#16
Alejandra V Quiroga, Paula Aphalo, Agustina Estefanía Nardo, María Cristina Añón
Among the factors affecting the development of cardiovascular diseases, hypertension is one of the most important. Research done on amaranth proteins has demonstrated their hypotensive capacity in vivo and in vitro; nevertheless the mechanism underlying this effect remains unclear. The aim of this study was to analyze in vitro the inhibition of peptides derived from an amaranth hydrolysate (AHH) on other RAS enzymes other than ACE. The chymase and renin activities were studied. AHH was not able to inhibit chymase activity although a dose-response effect was found on renin activity (IC50 0...
August 14, 2017: Journal of Agricultural and Food Chemistry
https://www.readbyqxmd.com/read/28805084/covalent-immobilisation-of-transglutaminase-stability-and-applications-in-protein-pegylation
#17
Antonella Grigoletto, Anna Mero, Hiroki Yoshioka, Oddone Schiavon, Gianfranco Pasut
Microbial transglutaminase enzyme (mTGase) is an extremely useful enzyme that is increasingly employed in the food and pharmaceutical industries and as a tool for protein modification and tagging. The current study describes how we immobilised mTGase (iTGase) on a solid support to improve its stability during the PEGylation process by which polyethylene glycol chains are attached to protein and peptide drugs. When the enzyme was immobilised at the N-terminal sequence on agarose beads, it retained more than 53% of its starting activity...
August 13, 2017: Journal of Drug Targeting
https://www.readbyqxmd.com/read/28805060/substrate-induced-facilitated-dissociation-of-competitive-inhibitor-from-the-active-site-of-o-acetyl-serine-sulfhydrylase-reveal-a-competitive-allostery-mechanism
#18
Appu Kumar Singh, Mary Krishna Ekka, Abhishek Kaushik, Vaibhav Kumar Pandya, Ravi Pratap Singh, Srijita Banerjee, Monica Mittal, Vijay Singh, Sangaralingam Kumaran
By classical competitive-antagonism, substrate and competitive-inhibitor must bind mutually exclusively to the active site. The competitive inhibition of O-acetyl serine sulfhydrylase (OASS) by C-terminal of serine acetyltransferase (SAT) presents a paradox, because the C-terminal of SAT binds to the active site of OASS with 4-6 log fold (104 -106) more affinity than that of the substrate. Therefore, we employed multiple approaches to understand how substrate gains access to OASS active site under physiological conditions...
August 14, 2017: Biochemistry
https://www.readbyqxmd.com/read/28805014/time-temperature-indicator-based-on-enzymatic-degradation-of-dye-loaded-polyhydroxybutyrate
#19
Preetam Anbukarasu, Dominic Sauvageau, Anastasia L Elias
An enzyme activated time-temperature indicator (TTI) which produces a direct colour change concomitant to variations in integrated time and temperature conditions is described. This direct colour change is realised by degrading a dye-loaded polyhydroxybutyrate (PHB) film by a depolymerase enzyme. The degradation of the PHB film by the enzyme causes the release of the dye in solution, which in turn undergoes an optical transition from clear to coloured with elapsing time. Macroscopic and microscopic optical observations confirms the uniform distribution of the dye in the PHB film...
August 14, 2017: Biotechnology Journal
https://www.readbyqxmd.com/read/28803882/changes-in-coumarin-kinetics-and-subcellular-localization-of-cyp2e1-contribute-to-bile-duct-damage-and-reduce-hepatocellular-damage-after-repeated-administration-of-coumarin-in-rats
#20
Yasuhiro Tanaka, Wataru Fujii, Hisako Hori, Yoshinori Kitagawa, Kiyokazu Ozaki
Coumarin exhibits different hepatotoxicity in rats depending on the administration frequency. To investigate the underlying mechanisms for the differences, we administered coumarin to rats as a single dose or repeatedly for 4 weeks. We found large increases in blood levels of liver enzymes and noticeable centrilobular hepatic necrosis after a single dose of coumarin. After repeated administration, enzyme levels mildly increased, while those of γ-GTP and total bilirubin significantly increased, suggesting bile duct damage...
August 10, 2017: Toxicology Letters
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