The Experts below are selected from a list of 258 Experts worldwide ranked by ideXlab platform
Ronald Breslow - One of the best experts on this subject based on the ideXlab platform.
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High Rates and Substrate Selectivities in Water by Polyvinylimidazoles as Transaminase Enzyme Mimics with Hydrophobically Bound Pyridoxamine Derivatives as CoEnzyme Mimics
Journal of the American Chemical Society, 2009Co-Authors: Rachid Skouta, Ronald BreslowAbstract:Free-radical polymers of 4-vinylimidazole and copolymers with 1-dodecyl-4-vinylimidazole were used as Enzyme Mimics to transaminate pyruvic acid to alanine, phenylpyruvic acid to phenylalanine, and indole-3-pyruvic acid to tryptophan in water at pH 7.5 and 20 °C using pyridoxamines carrying hydrophobic side chains as coEnzyme Mimics. The best Enzyme Mimic accelerated the transamination of indole-3-pyruvic acid by a factor of 4 million relative to the rate without the polymer, a higher rate ratio than we had previously achieved with a polyaziridine-based Enzyme Mimic. The properties of various polyvinylimidazoles were compared, including those prepared with the RAFT modification of the polymerization process.
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A potent polymer/pyridoxamine Enzyme Mimic.
Journal of the American Chemical Society, 2002Co-Authors: Ronald BreslowAbstract:An Enzyme Mimic consisting of pyridoxamines covalently linked to polyethyleneimine carrying long-chain alkyl groups converts pyruvic acid to dl-alanine with as much as an 8000-fold acceleration relative to the reaction with simple pyridoxamine at the same pyridoxamine concentration. The acceleration by polymer is a strong function of the length of the alkyl chains that are appended. The polymer furnishes acid and base groups to catalyze the proton transfers that are involved in transamination.
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a potent polymer pyridoxamine Enzyme Mimic
Journal of the American Chemical Society, 2002Co-Authors: Ronald BreslowAbstract:An Enzyme Mimic consisting of pyridoxamines covalently linked to polyethyleneimine carrying long-chain alkyl groups converts pyruvic acid to dl-alanine with as much as an 8000-fold acceleration relative to the reaction with simple pyridoxamine at the same pyridoxamine concentration. The acceleration by polymer is a strong function of the length of the alkyl chains that are appended. The polymer furnishes acid and base groups to catalyze the proton transfers that are involved in transamination.
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an Enzyme Mimic that hydrolyzes an unactivated ester with catalytic turnover
Tetrahedron Letters, 2000Co-Authors: Ronald BreslowAbstract:Abstract The Cu(II) complex of a cyclodextrin dimer linked by a bipyridyl unit catalyzes the hydrolysis of an unactivated doubly-bound benzyl ester.
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ester hydrolysis by a catalytic cyclodextrin dimer Enzyme Mimic with a metallobipyridyl linking group
Journal of the American Chemical Society, 1997Co-Authors: Biliang Zhang, Ronald BreslowAbstract:A β-cyclodextrin dimer with a linking bipyridyl group is synthesized as a catalyst precursor, a holoEnzyme Mimic. It binds both ends of potential substrates into the two different cyclodextrin cavities, holding the substrate ester carbonyl group directly above a metal ion bound to the bipyridyl unit. The result is very effective ester hydrolysis with good turnover catalysis. For example, a Cu(II) complex accelerates the rate of hydrolysis of several nitrophenyl esters by a factor of 104−105, with at least 50 turnovers and no sign of product inhibition. In the best case, with an added nucleophile that also binds to the metal ion, a rate acceleration of 1.45 × 107 over the background reaction rate was observed. Hydrolysis by a catalyst with only one cyclodextrin binding group is significantly slower than in the bidentate binding cases. As expected, the binding of a transition state analogue to these catalysts is stronger with the metal ion present than without. This and kinetic evidence point to a mechanism...
Jun Tang - One of the best experts on this subject based on the ideXlab platform.
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deuterohemin peptide Enzyme Mimic embedded metal organic frameworks through biomimetic mineralization with efficient atrp catalytic activity
ACS Applied Materials & Interfaces, 2017Co-Authors: Wei Jiang, Xinghuo Wang, Jiawen Chen, Yi Ding, Quanshun Li, Jun TangAbstract:An Enzyme Mimic harboring iron porphyrin (DhHP-6) embedded in zeolite imidazolate framework-8 (ZIF-8) was constructed through a biomimetic mineralization approach to obtain composite DhHP-6@ZIF-8. The composite was then used as a catalyst in the atom transfer radical polymerization (ATRP) of poly(ethylene glycol) methyl ether methacrylate (PEGMA500) in which poly(PEGMA500) could be synthesized with monomer conversion of 76.1% and Mn of 45 900 g/mol, stronger than that obtained when using free DhHP-6 as a catalyst. More importantly, it could efficiently overcome the drawbacks of free DhHP-6 and achieve the easy separation of DhHP-6 from the catalytic system and the elimination of iron residues in the synthesized polymer. In addition, it exhibited an enhanced recyclability with monomer conversion of 75.7% after five cycles and favorable stability during the ATRP reaction with <3.0% of DhHP-6 release within 100 h. Thus, the Enzyme Mimic–ZIF-8 composite developed through biomimetic mineralization can be poten...
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Deuterohemin-Peptide Enzyme Mimic-Embedded Metal-Organic Frameworks through Biomimetic Mineralization with Efficient ATRP Catalytic Activity
ACS Applied Materials & Interfaces, 2017Co-Authors: Wei Jiang, Xinghuo Wang, Jiawen Chen, Yi Ding, Quanshun Li, Jun TangAbstract:An Enzyme Mimic harboring iron porphyrin (DhHP-6) embedded in zeolite imidazolate framework-8 (ZIF-8) was constructed through a biomimetic mineralization approach to obtain composite DhHP-6@ZIF-8. The composite was then used as a catalyst in the atom transfer radical polymerization (ATRP) of poly(ethylene glycol) methyl ether methacrylate (PEGMA500) in which poly(PEGMA500) could be synthesized with monomer conversion of 76.1% and Mn of 45 900 g/mol, stronger than that obtained when using free DhHP-6 as a catalyst. More importantly, it could efficiently overcome the drawbacks of free DhHP-6 and achieve the easy separation of DhHP-6 from the catalytic system and the elimination of iron residues in the synthesized polymer. In addition, it exhibited an enhanced recyclability with monomer conversion of 75.7% after five cycles and favorable stability during the ATRP reaction with
Chunchuan Gu - One of the best experts on this subject based on the ideXlab platform.
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copper ii coated fe 3 o 4 nanoparticles as an efficient Enzyme Mimic for colorimetric detection of hydrogen peroxide
Mikrochimica Acta, 2019Co-Authors: Hanxiao Xu, Linan Zhang, Lihua Li, Chunchuan GuAbstract:The authors describe the preparation of Cu(II)-coated Fe3O4) nanoparticles (NPs) that possess excellent peroxidase-like activity. The NPs were formed by chelation between Cu(II) ions and the oxygen functional groups of sodium ligninsulfonate. The morphology and structure of the NPs were characterized by scanning electron microscopy, transmission electron microscopy, X-ray powder diffraction, X-ray photoelectron spectroscopy, and Fourier transform infrared spectroscopy. The NPs have an average diameter of 220 nm. They are shown to be viable peroxidase Mimics that can catalyze the oxidation of 3,3′,5,5′-tetramethylbenzidine by hydrogen peroxide to produce a blue coloration. The findings were used to design a colorimetric assay that has a linear response in the 2.5 to 100 μM H2O2 concentration range and a 0.2 μM detection limit. The assay excels by its selectivity, high sensitivity, good selectivity, portability and cost efficiency.
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hollow and porous nickel sulfide nanocubes prepared from a metal organic framework as an efficient Enzyme Mimic for colorimetric detection of hydrogen peroxide
Analytical and Bioanalytical Chemistry, 2019Co-Authors: Hanxiao Xu, Zhiheng Huang, Dujuan Li, Chunchuan GuAbstract:Hollow, porous NiS nanocubes were prepared by a hydrothermal method starting from Ni–Co Prussian blue analogue nanocubes as the template. The morphology and structure of the NiS nanocubes were tuned by adjustment of the ion-exchange rate and the degree of chemical etching, and they were characterized by scanning electron microscopy, energy-dispersive X-ray spectroscopy, transmission electron microscopy, X-ray diffraction, and nitrogen sorption measurements. The NiS nanocubes are shown to act as a peroxidase Mimic that can catalyze the oxidization of 3,3′,5,5′-tetramethylbenzidine by hydrogen peroxide (H2O2), producing a visible color change, for which the absorbance is best measured at 652 nm. The outstanding activity may result from the unique structure of the NiS nanocubes. The catalytic oxidation follows Michaelis–Menten kinetics and shows a ping-pong mechanism of Enzyme action. The findings were used to develop a rapid, sensitive, and selective colorimetric H2O2 assay with a response that is linear in the 4–40 μM range with a detection limit of 1.72 μM (signal-to-noise ratio of 3).
Wei Jiang - One of the best experts on this subject based on the ideXlab platform.
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deuterohemin peptide Enzyme Mimic embedded metal organic frameworks through biomimetic mineralization with efficient atrp catalytic activity
ACS Applied Materials & Interfaces, 2017Co-Authors: Wei Jiang, Xinghuo Wang, Jiawen Chen, Yi Ding, Quanshun Li, Jun TangAbstract:An Enzyme Mimic harboring iron porphyrin (DhHP-6) embedded in zeolite imidazolate framework-8 (ZIF-8) was constructed through a biomimetic mineralization approach to obtain composite DhHP-6@ZIF-8. The composite was then used as a catalyst in the atom transfer radical polymerization (ATRP) of poly(ethylene glycol) methyl ether methacrylate (PEGMA500) in which poly(PEGMA500) could be synthesized with monomer conversion of 76.1% and Mn of 45 900 g/mol, stronger than that obtained when using free DhHP-6 as a catalyst. More importantly, it could efficiently overcome the drawbacks of free DhHP-6 and achieve the easy separation of DhHP-6 from the catalytic system and the elimination of iron residues in the synthesized polymer. In addition, it exhibited an enhanced recyclability with monomer conversion of 75.7% after five cycles and favorable stability during the ATRP reaction with <3.0% of DhHP-6 release within 100 h. Thus, the Enzyme Mimic–ZIF-8 composite developed through biomimetic mineralization can be poten...
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Deuterohemin-Peptide Enzyme Mimic-Embedded Metal-Organic Frameworks through Biomimetic Mineralization with Efficient ATRP Catalytic Activity
ACS Applied Materials & Interfaces, 2017Co-Authors: Wei Jiang, Xinghuo Wang, Jiawen Chen, Yi Ding, Quanshun Li, Jun TangAbstract:An Enzyme Mimic harboring iron porphyrin (DhHP-6) embedded in zeolite imidazolate framework-8 (ZIF-8) was constructed through a biomimetic mineralization approach to obtain composite DhHP-6@ZIF-8. The composite was then used as a catalyst in the atom transfer radical polymerization (ATRP) of poly(ethylene glycol) methyl ether methacrylate (PEGMA500) in which poly(PEGMA500) could be synthesized with monomer conversion of 76.1% and Mn of 45 900 g/mol, stronger than that obtained when using free DhHP-6 as a catalyst. More importantly, it could efficiently overcome the drawbacks of free DhHP-6 and achieve the easy separation of DhHP-6 from the catalytic system and the elimination of iron residues in the synthesized polymer. In addition, it exhibited an enhanced recyclability with monomer conversion of 75.7% after five cycles and favorable stability during the ATRP reaction with
Xingguang Su - One of the best experts on this subject based on the ideXlab platform.
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a novel Enzyme Mimic nanosensor based on quantum dot au nanoparticle silica mesoporous microsphere for the detection of glucose
Analytica Chimica Acta, 2014Co-Authors: Yang Li, Xinyan Wang, Xingguang SuAbstract:Abstract QD-Au NP@silica mesoporous microspheres have been fabricated as a novel Enzyme-Mimic nanosensor. CdTe quantum dots (QDs) were loaded into the core, and Au nanoparticles (NPs) were encapsulated in the outer mesoporous shell. QDs and Au NPs were separated in the different space of the nanosensor, which prevent the potential energy or electron transfer process between QDs and Au NPs. As biomimetic catalyst, Au NPs in the mesoporous silica shell can catalytically oxidize glucose as glucose oxidase (GOx)-Mimicking. The resultant hydrogen peroxide can quench the photoluminescence (PL) signal of QDs in the microsphere core. Therefore the nanosensor based on the decrease of the PL intensity of QDs was established for the glucose detection. The linear range for glucose was in the range of 5–200 μM with a detection limit (3 σ ) of 1.32 μM.
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A novel Enzyme-Mimic nanosensor based on quantum dot-Au nanoparticle@silica mesoporous microsphere for the detection of glucose
Analytica Chimica Acta, 2014Co-Authors: Yang Li, Xinyan Wang, Qiang Ma, Xingguang SuAbstract:Abstract QD-Au NP@silica mesoporous microspheres have been fabricated as a novel Enzyme-Mimic nanosensor. CdTe quantum dots (QDs) were loaded into the core, and Au nanoparticles (NPs) were encapsulated in the outer mesoporous shell. QDs and Au NPs were separated in the different space of the nanosensor, which prevent the potential energy or electron transfer process between QDs and Au NPs. As biomimetic catalyst, Au NPs in the mesoporous silica shell can catalytically oxidize glucose as glucose oxidase (GOx)-Mimicking. The resultant hydrogen peroxide can quench the photoluminescence (PL) signal of QDs in the microsphere core. Therefore the nanosensor based on the decrease of the PL intensity of QDs was established for the glucose detection. The linear range for glucose was in the range of 5–200 μM with a detection limit (3 σ ) of 1.32 μM.