79566-13-5Relevant academic research and scientific papers
Novel screening assay for antioxidant protection against peroxyl radical-induced loss of protein function
Bertolini, Francesca,Novaroli, Laura,Carrupt, Pierre-Alain,Reist, Marianne
, p. 2931 - 2944 (2007)
Oxidative damage to proteins, implicated amongst other in the etiology and progression of Parkinson's disease (PD) and Alzheimer's disease (AD), results in the loss of specific biological protein function. A simple, sensitive, and cost-effective fluorimetric test to assess the antioxidant capacity of new chemical entities to protect proteins from loss of activity caused by reactive oxygen species (ROS) was developed using alkaline phosphatase (ALP) as model protein. Protein oxidation was induced by 2,2′-azobis(2- methylpropionamidine) dihydrochloride (AAPH) and the decrease in catalytic activity of ALP to hydrolyze 4-methylumbelliferyl phosphate (4-MUP) to fluorescent 4-methylumbelliferone (4-MU) was monitored as a marker of protein degradation. According to their capacity to protect ALP from peroxyl radical-induced activity loss, ten reference antioxidants were divided into three classes, namely efficient (pIC50 > 5 for quercetin, chlorogenic acid, caffeic acid, mangiferin, and resveratrol), intermediate (4 50 ≤ 5 for melatonin, trolox, and ascorbic acid), and poor antioxidants (pIC50 4 for glutathione and D-mannitol). Multifunctional drugs, having the ability to interact with several disease-related targets are of interest in PD. Therefore, the capacity of three catechol-O-methyltransferase (COMT) inhibitors, entacapone, nitecapone, and tolcapone to protect ALP from oxidative damage was also investigated and found to be very similar to the most potent reference antioxidants.
Inhibition of neuraminidase with neuraminic acid C-glycosides
Wang, Qun,Wolff, Michael,Polat, Tuelay,Du, Yuguo,Linhardt, Robert J.
, p. 941 - 944 (2000)
Neuraminic (sialic) acid based α-C-glycosides have been synthesized and their inhibitory activity towards bacterial neuraminidase (sialidase) was examined. While some C-glycosides were found to be potent inhibitors (K(i) 15-30 μM) of this neuraminidase, others afforded no measurable activity. The structure-activity relationship of these C-glycosides is discussed in the context of other previously reported sialidase inhibitors. (C) 2000 Elsevier Science Ltd. All rights reserved.
Fluorescent Neuraminidase Assay Based on Supramolecular Dye Capture after Enzymatic Cleavage
Liu, Wenqi,Gómez-Durán, César F. A.,Smith, Bradley D.
, p. 6390 - 6395 (2017)
A conceptually new type of enzymatic cleavage assay is reported that utilizes in situ supramolecular capture of the fluorescent product. A squaraine-derived substrate with large blocking groups at each end of its structure cannot be threaded by a tetralactam macrocycle until the blocking groups are removed by enzyme cleavage. A prototype design responds to viral neuraminidase, an indicator of influenza infection, and also measures susceptibility of the sample to neuraminidase inhibitor drugs. The substrate structure incorporates three key features: (a) a bis(4-amino-3-hydroxyphenyl)squaraine core with bright deep-red fluorescence and excellent photostability, (b) an N-methyl group at each end of the squaraine core that ensures fast macrocycle threading kinetics, and (c) sialic acid blocking groups that prevent macrocycle threading until they are removed by viral neuraminidase. The enzyme assay can be conducted in aqueous solution where dramatic colorimetric and fluorescence changes are easily observed by the naked eye. Alternatively, affinity capture beads coated with macrocycle can be used to immobilize the liberated squaraine and enable a range of heterogeneous analysis options. With further optimization, this new type of neuraminidase assay may be useful in a point of care clinic to rapidly diagnose influenza infection and also determine which of the approved antiviral inhibitor drugs is likely to be the most effective treatment for an individual patient. The assay design is generalizable and can be readily modified to monitor virtually any type of enzyme-catalyzed cleavage reaction.
High yield preparation of ganglioside GM1 using recombinant sialidase from Cellulosimicrobium cellulans
Yuan, Ye,Ji, Li,Hu, Yanbo,Hu, Chenxing,Chen, Honglei,Gao, Juan,Zhou, Yifa
, p. 92 - 97 (2017)
Cellulosimicrobium cellulans employs extracellular sialidase to selectively convert polysialogangliosides to ganglioside GM1. We cloned this novel sialidase gene (ccsia) from C. cellulans sp. 21, and overexpressed recombinant sialidase (CcSia) protein in E. coli BL21 (DE3) by high cell density fermentation. The presence of an N-terminal hexa-His tag allowed for purification using nickel affinity chromatography (2.3-fold, specific activity 41.5?U/mg). As determined by gel electrophoresis and gel filtration chromatography, the molecular weight of CcSia was found to be about 75?kDa, consistent with sequence analysis (75,271?Da). CcSia transformed polysialogangliosides GD1a, GD1b and GT1b into GM1. For this reaction, the response surface approach showed that optimal conditions in a 1-L system were 2?h incubation at 32.5?°C and pH 5.2, with substrate concentrations of 10?g/L and crude enzyme concentration 1?g/L, respectively. Under above conditions, 10?g/L of ganglioside was completely converted to the product GM1 with a yield of 52%. Our studies demonstrate CcSia could be used for industrial preparation of ganglioside GM1 by the pharmaceutical industry.
Highly sensitive peptide-based probes for protein tyrosine phosphatase activity utilizing a fluorogenic mimic of phosphotyrosine
Mitra, Sayantan,Barrios, Amy M.
, p. 5142 - 5145 (2005)
Fluorescent probes that can be incorporated into peptides and proteins are in high demand, with applications ranging from cellular imaging to binding and activity assays. Here, we report the high yielding synthesis of an enantiomerically pure phosphocoumarin-based amino acid and its incorporation into peptides via standard solid-phase peptide synthesis methodologies. Peptides containing this new amino acid serve as highly sensitive fluorogenic probes for protein tyrosine phosphatase activity.
The phosphatase-like activity of zirconium oxide nanoparticles and their application in near-infrared intracellular imaging
Hu, Lianzhe,Hu, Xilu,Huang, Ting,Liao, Hong,Wang, Min
, p. 4428 - 4433 (2020)
In this study, the phosphatase mimetic activity of zirconium oxide nanoparticles (ZrO2NPs) has been demonstrated. They can effectively catalyze the dephosphorylation of a series of commercial fluorogenic and chromogenic substrates of natural phosphatases. Compared with natural phosphatases, ZrO2NPs possess several advantages such as low cost, facile preparation procedures, and high stability in a broader pH range or at high temperatures. In addition, the activity of ZrO2NPs toward some important biomolecules was investigated. The ZrO2NPs can catalyze the dephosphorylation of ATP ando-phospho-l-tyrosine, but they cannot react with DNA strands. These data are important for the further bio-related applications of ZrO2NPs. Finally, the potential application of ZrO2NPs in intracellular imaging is also demonstrated by using a near-infrared fluorescent substrate of alkaline phosphatase.
Visualizing the reaction coordinate of an O-GlcNAc hydrolase
He, Yuan,Macauley, Matthew S.,Stubbs, Keith A.,Vocadlo, David J.,Davies, Gideon J.
, p. 1807 - 1809 (2010)
(Chemical Presented) N-Acetylglucosamine β-O-linked to serine and threonine residues of nucleocytoplasmic proteins (O-GlcNAc) has been linked to neurodegeneration, cellular stress response, and transcriptional regulation. Removal of O-GlcNAc is catalyzed by O-GlcNAcase (OGA) using a substrate-assisted catalytic mechanism. Here we define the reaction coordinate using chemical approaches and directly observe both a Michaelis complex and the oxazoline intermediate. Copyright
Design and characterization of immobilized enzymes in microfluidic systems
Mao, Hanbin,Yang, Tinglu,Cremer, Paul S.
, p. 379 - 385 (2002)
Herein we report the fabrication, characterization, and use of total analytical microsystems containing surface-immobilized enzymes. Streptavidin-conjugated alkaline phosphatase was linked to biotinylated phospholipid bilayers coated inside poly(dimethylsiloxane) microchannels and borosilicate microcapillary tubes. Rapid determination of enzyme kinetics at many different substrate concentrations was made possible by carrying out laminar flowcontrolled dilution on-chip. This allowed Lineweaver-Burk analysis to be performed from a single experiment with all the data collected simultaneously. The results revealed an enzyme turnover number of 51.1 ± 3.2 s-1 for this heterogeneous system. Furthermore, the same enzyme immobilization strategy was extended to demonstrate that multiple chemical reactions could be performed in sequence by immobilizing various enzymes in series. Specifically, the presence of glucose was detected by two coupled steps employing immobilized avidinD-conjugated glucose oxidase and streptavidin-conjugated horseradish peroxidase.
Characterization of partially purified α-glucosidase in the insoluble fraction of bovine crystalline lens
Kamei,Fujiyama
, p. 1133 - 1137 (1995)
Two fractions of neutral α-glucosidase were partially purified from the insoluble fraction of bovine lens. This is the first report of such an event to the best of our knowledge. The apparent native molecular weights of these fractions were 121 kDa (fraction-I) and 254 kDa (fraction-II). Both fractions contained three polypeptides with molecular weights of 21, 25 and 30 kDa, although the proportion of these peptides was different in both fractions. The optimal pH of fraction-I and fraction-II was pH 6.0 and 6.5, and the optimal temperature for both fractions was approximately 50°C. The K(m) values of fractions-I and -II for 4-methylumbelliferyl-α-glucopyranoside were 0.086, and 0.192 mM. The activities of these enzymes were inhibited strongly by HgCl2 and slightly by D-iodoacetic acid, but not by D-turanose. From this, we suggest that the enzyme in the insoluble fraction of bovine lens may he a cytoplasmic neutral α-glucosidase which binds to the cell membrane.
Psammaplin A, a chitinase inhibitor isolated from the Fijian marine sponge Aplysinella rhax
Tabudravu,Eijsink,Gooday,Jaspars,Komander,Legg,Synstad,Van Aalten
, p. 1123 - 1128 (2002)
Several brominated tyrosine derived compounds, psammaplins A (1), K (2) and (3) as well as bisaprasin (4) were isolated from the Fijian marine sponge Aplysinella rhax during a bioassay guided isolation protocol. Their structures were determined using NMR and MS techniques. Psammaplin A was found to moderately inhibit chitinase B from Serratia marcescens, the mode of inhibition being non-competitive. Crystallographic studies suggest that a disordered psammaplin A molecule is bound near the active site. Interestingly, psammaplin A was found to be a potent antifungal agent. Copyright
