Topic
Substrate (chemistry)
About: Substrate (chemistry) is a research topic. Over the lifetime, 35902 publications have been published within this topic receiving 740722 citations. The topic is also known as: enzyme substrate.
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TL;DR: In this article, the relationship between apparent enzyme kinetic parameters and nanomaterials structure is investigated in order to rationally design the catalytic activity of the Au nanorods.
Abstract: Au nanorods @ Pt nanodots core/shell nanostructures, prepared by the Au nanorods (NRs)-mediated growth, exhibit dual functional enzyme-like (peroxidase and oxidase-like) activities. From the viewpoint of enzyme mimics, the relationship between apparent enzyme kinetic parameters and nanomaterials structure is investigated in order to rationally design the catalytic activity. Using peroxidase-like properties of the Au@Pt NRs, the determination of hydrogen peroxide (H2O2) was demonstrated with a limit of detection (LOD) of 4.5 × 10−5 M and a linear range of 4.5 × 10−5–1 × 10−3 M using o-phenylenediamine (OPD) as chromogenic substrate. Furthermore, in combination with highly specific reactions provided by natural enzymes, selective detections of glucose and lipophilic cholesterol were demonstrated with similar LODs and linear ranges. Additionally, owing to the specific oxidase-like activity of the Au@Pt NRs (ascorbate oxidase), interference of ascorbic acid in the detection of glucose could be eliminated. In conclusion, considering the flexibility in the design of nanomatererials, there is a lot of space to improve their activity and explore their potential applications, especially in relatively harsh conditions.
174 citations
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20 Nov 2009TL;DR: In this paper, a front end line (FEOL) plasma mediated ashing process for removing organic material from a substrate generally includes exposing the substrate to the plasma to selectively remove photoresist, implanted photoresists, polymers and/or residues from the substrate.
Abstract: Front end of line (FEOL) plasma mediated ashing processes for removing organic material from a substrate generally includes exposing the substrate to the plasma to selectively remove photoresist, implanted photoresist, polymers and/or residues from the substrate, wherein the plasma contains a ratio of active nitrogen and active oxygen that is larger than a ratio of active nitrogen and active oxygen obtainable from plasmas of gas mixtures comprising oxygen gas and nitrogen gas. The plasma exhibits high throughput while minimizing and/or preventing substrate oxidation and dopant bleaching. Plasma apparatuses are also described.
174 citations
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TL;DR: The term “laccase-like multi-copper oxidase” (LMCO) is proposed to be introduced in addition to the term laccase that is currently used exclusively for the enzyme originally identified from the sap of the lacquer tree Rhus vernicifera.
Abstract: Laccases (EC 1.10.3.2) are multi-copper oxidases that catalyse the one-electron oxidation of a broad range of compounds including substituted phenols, arylamines and aromatic thiols to the corresponding radicals. Owing to their broad substrate range, copper-containing laccases are versatile biocatalysts, capable of oxidizing numerous natural and non-natural industry-relevant compounds, with water as the sole by-product. In the present study, 10 of the 11 multi-copper oxidases, hitherto considered to be laccases, from fungi, plant and bacterial origin were compared. A substrate screen of 91 natural and non-natural compounds was recorded and revealed a fairly broad but distinctive substrate spectrum amongst the enzymes. Even though the enzymes share conserved active site residues we found that the substrate ranges of the individual enzymes varied considerably. The EC classification is based on the type of chemical reaction performed and the actual name of the enzyme often refers to the physiological substrate. However, for the enzymes studied in this work such classification is not feasible, even more so as their prime substrates or natural functions are mainly unknown. The classification of multi-copper oxidases assigned as laccases remains a challenge. For the sake of simplicity we propose to introduce the term “laccase-like multi-copper oxidase” (LMCO) in addition to the term laccase that we use exclusively for the enzyme originally identified from the sap of the lacquer tree Rhus vernicifera.
174 citations
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TL;DR: A mechanism for the solvent-mediated hydrolysis of substrate by sialidase that requires the formation of an endocyclic sialosyl cation transition-state intermediate is proposed.
Abstract: The enzyme mechanism of sialidase from influenza virus has been investigated by kinetic isotope methods, NMR, and a molecular dynamics simulation of the enzyme-substrate complex. Comparison of the reaction rates obtained with the synthetic substrate 4-methylumbelliferyl-N-acetyl-α-D-neuraminic acid and the [3,3-2H]-substituted substrate revealed β-deuterium isotope effects for V/Km ranging over 1.09–1.15 in the pH range 6.0–9.5, whereas the effects observed for V in this pH range increased from 0.979 to 1.07. In D2O, βDV/Km was slightly increased by 2% and 5% at pD 6.0 and 9.5 respectively, while βDV was unchanged. Solvent isotope effects of 1.74 were obtained for both βDV/Km and βDV at pD 9.5, with βDV/Km decreasing and βDV remaining constant at acidic pD. 1H-NMR experiments confirmed that the initial product of the reaction is the α-anomer of N-acetyl-D-neuraminic acid. Molecular dynamics studies identified a water molecule in the crystal structure of the sialidase-N-acetyl-D-neuraminic acid complex which is hydrogen-bonded to Asp151 and is available to act as a proton donor source in the enzyme reaction. The results of this study lead us to propose a mechanism for the solvent-mediated hydrolysis of substrate by sialidase that requires the formation of an endocyclic sialosyl cation transition-state intermediate.
174 citations
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TL;DR: By plasma-enhanced chemical vapor deposition, a molybdenum disulfide (MoS2) thin film is synthesized directly on a wafer-scale plastic substrate at below 300 °C, revealing its potential for flexible sensing devices.
Abstract: By plasma-enhanced chemical vapor deposition, a molybdenum disulfide (MoS2 ) thin film is synthesized directly on a wafer-scale plastic substrate at below 300 °C. The carrier mobility of the films is 3.74 cm(2) V(-1) s(-1) . Also, humidity is successfully detected with MoS2 -based sensors fabricated on the flexible substrate, which reveals its potential for flexible sensing devices.
174 citations