The Experts below are selected from a list of 234 Experts worldwide ranked by ideXlab platform
Yan Chen - One of the best experts on this subject based on the ideXlab platform.
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dual emission fluorescent silver nanoclusters for sensitive detection of the biological Coenzyme NAD NADh
Analytical Biochemistry, 2016Co-Authors: Yufeng Yuan, Kehan Huang, Mengfang Chang, Cuifang Qin, Sanjun Zhang, Haifeng Pan, Yan ChenAbstract:Fluorescent silver nanoclusters (Ag NCs) displaying dual-excitation and dual-emission properties have been developed for the specific detection of NAD(+) (nicotinamide adenine dinucleotide, oxidized form). With the increase of NAD(+) concentrations, the longer wavelength emission (with the peak at 550 nm) was gradually quenched due to the strong interactions between the NAD(+) and Ag NCs, whereas the shorter wavelength emission (peaking at 395 nm) was linearly enhanced. More important, the dual-emission intensity ratio (I395/I550), fitting by a single-exponential decay function, can efficiently detect various NAD(+) levels from 100 to 4000 μM, as well as label NAD(+)/NADH (reduced form of NAD) ratios in the range of 1-50.
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Dual emission fluorescent silver nanoclusters for sensitive detection of the biological Coenzyme NAD+/NADH
Analytical biochemistry, 2015Co-Authors: Yufeng Yuan, Kehan Huang, Mengfang Chang, Cuifang Qin, Sanjun Zhang, Haifeng Pan, Yan ChenAbstract:Fluorescent silver nanoclusters (Ag NCs) displaying dual-excitation and dual-emission properties have been developed for the specific detection of NAD(+) (nicotinamide adenine dinucleotide, oxidized form). With the increase of NAD(+) concentrations, the longer wavelength emission (with the peak at 550 nm) was gradually quenched due to the strong interactions between the NAD(+) and Ag NCs, whereas the shorter wavelength emission (peaking at 395 nm) was linearly enhanced. More important, the dual-emission intensity ratio (I395/I550), fitting by a single-exponential decay function, can efficiently detect various NAD(+) levels from 100 to 4000 μM, as well as label NAD(+)/NADH (reduced form of NAD) ratios in the range of 1-50.
Yi-si Feng - One of the best experts on this subject based on the ideXlab platform.
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Selective Aerobic Oxidation of Sulfides to Sulfoxides Catalyzed by Coenzyme NAD+ Models.
ChemInform, 2011Co-Authors: Yi-cheng Lin, Xin Wan, Chun-yan Yang, Yi-si FengAbstract:Chemoselective oxidation of aromatic sulfides towards sulfoxides is smoothly achieved using oxygen as oxidant and an NAD+ model as organocatalyst.
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Selective aerobic oxidation of sulfides to sulfoxides catalyzed by Coenzyme NAD+ models
Tetrahedron, 2010Co-Authors: Yi-cheng Lin, Xin Wan, Chun-yan Yang, Yi-si FengAbstract:Abstract Coenzyme NAD+ models can be applied in the photooxygenation of sulfides to sulfoxides as organocatalysts at room temperature. A series of sulfoxides are synthesized easily with this protocol and the possible mechanism is discussed. This procedure provides a reliable approach to the clean production of useful sulfoxides in synthetic chemistry.
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Photocatalytic oxidation of primary and secondary benzyl alcohol catalyzed by two Coenzyme NAD+ models
Chinese Chemical Letters, 2007Co-Authors: Yi-si FengAbstract:Abstract Photocatalytic oxidation of primary and secondary benzyl alcohol to corresponding benzaldehyde or acetophenone using Acr+ClO4− or PhAcr+ClO4− as photocatalysts under visible light irradiation at room temperature.
Yufeng Yuan - One of the best experts on this subject based on the ideXlab platform.
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dual emission fluorescent silver nanoclusters for sensitive detection of the biological Coenzyme NAD NADh
Analytical Biochemistry, 2016Co-Authors: Yufeng Yuan, Kehan Huang, Mengfang Chang, Cuifang Qin, Sanjun Zhang, Haifeng Pan, Yan ChenAbstract:Fluorescent silver nanoclusters (Ag NCs) displaying dual-excitation and dual-emission properties have been developed for the specific detection of NAD(+) (nicotinamide adenine dinucleotide, oxidized form). With the increase of NAD(+) concentrations, the longer wavelength emission (with the peak at 550 nm) was gradually quenched due to the strong interactions between the NAD(+) and Ag NCs, whereas the shorter wavelength emission (peaking at 395 nm) was linearly enhanced. More important, the dual-emission intensity ratio (I395/I550), fitting by a single-exponential decay function, can efficiently detect various NAD(+) levels from 100 to 4000 μM, as well as label NAD(+)/NADH (reduced form of NAD) ratios in the range of 1-50.
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Dual emission fluorescent silver nanoclusters for sensitive detection of the biological Coenzyme NAD+/NADH
Analytical biochemistry, 2015Co-Authors: Yufeng Yuan, Kehan Huang, Mengfang Chang, Cuifang Qin, Sanjun Zhang, Haifeng Pan, Yan ChenAbstract:Fluorescent silver nanoclusters (Ag NCs) displaying dual-excitation and dual-emission properties have been developed for the specific detection of NAD(+) (nicotinamide adenine dinucleotide, oxidized form). With the increase of NAD(+) concentrations, the longer wavelength emission (with the peak at 550 nm) was gradually quenched due to the strong interactions between the NAD(+) and Ag NCs, whereas the shorter wavelength emission (peaking at 395 nm) was linearly enhanced. More important, the dual-emission intensity ratio (I395/I550), fitting by a single-exponential decay function, can efficiently detect various NAD(+) levels from 100 to 4000 μM, as well as label NAD(+)/NADH (reduced form of NAD) ratios in the range of 1-50.
Đurđa Vasić-rački - One of the best experts on this subject based on the ideXlab platform.
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A new concept for production of (3S,4R)-6-[(benzyloxycarbonyl)amino]-5,6-dideoxyhex-2-ulose, a precursor of D-fagomine
RSC Advances, 2015Co-Authors: Martina Sudar, Đurđa Vasić-rački, Zvjezdana Findrik, Anna Soler, Pere ClapésAbstract:A novel cascade reaction for the production of aldol adduct (3S,4R)-6-[(benzyloxycarbonyl)amino]-5,6-dideoxyhex-2-ulose was studied in this work. The strategy combines three enzymes in one pot: (i) horse liver alcohol dehydrogenase for the oxidation of N-Cbz-3-aminopropanol to the corresponding aldehyde, (ii) NADH oxidase for the regeneration of Coenzyme NAD+ and (iii) D-fructose-6-phosphate aldolase from E. coli A129S variant for the aldol addition of dihydroxyacetone to N-Cbz-3-aminopropanal. On the basis of preliminary experiments, optimization of the initial reaction conditions was done using statistical methods, i.e. factorial design of experiments. 79% yield of aldol adduct was achieved in the batch reactor after optimization.
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Coenzyme Regeneration in Hexanol Oxidation Catalyzed by Alcohol Dehydrogenase
Applied Biochemistry and Biotechnology, 2012Co-Authors: Ana Vrsalović Presečki, Katja Makovšek, Đurđa Vasić-račkiAbstract:The enzymatic ways of Coenzyme regeneration include the addition of a second enzyme to the system or the addition of the co-substrate. In the present study, both methods of enzymatic Coenzyme (NAD+) regeneration were studied and compared in the reaction of hexanol oxidation catalyzed by alcohol dehydrogenase (ADH). As a source of ADH, commercial isolated enzyme and the whole baker’s yeast cells were used. First, Coenzyme regeneration was employed in the reaction of acetaldehyde reduction catalyzed by the same enzyme that catalyzed the main reaction, and then NAD+ regeneration was applied in the reaction of pyruvate reduction catalyzed by l-lactate dehydrogenase (l-LDH). Hexanal was obtained as the product of hexanol oxidation catalyzed by isolated ADH while hexaonic acid was detected as a product of the same reaction catalyzed by baker’s yeast cells. All of the used biocatalysts were kinetically characterized. The mass reactions were described by the mathematical models. All models were validated in the batch reactor. One hundred percent hexanol conversion was obtained using permeabilized yeast cells using both methods of cofactor regeneration. By using isolated enzyme ADH, the higher conversion was achieved in a system with cofactor regeneration catalyzed by l-LDH.
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Coenzyme regeneration in the oxidation of amino acids
2007Co-Authors: Zvjezdana Findrik, Đurđa Vasić-račkiAbstract:There are various methods available for the stereoselective synthesis of optically pure amino acids [1]. One of these methods includes the use of L-amino acid dehydrogenases. Using these enzymes the synthesis of L-amino acid can be carried out from an -keto acid as a starting material, while D-amino acid can be synthesized from the corresponding racemate, by complete oxidation of L-amino acid followed by separation of an -keto acid [2]. Besides enantiomerically pure amino acids as valuable products, L-amino acid dehydrogenases can be used for an α -keto acid synthesis. In all cases Coenzyme regeneration [3] system is necessary to ensure the equilibrium shift towards the wanted products. In this paper three different Coenzyme (NAD+) regeneration systems were compared in their action in the reaction of L-methionine oxidation. L-methionine oxidation catalyzed by L-phenylalanine dehydrogenase (L-PheDH) from Rhodococcus sp. M4 is an equilibrium reaction. Without Coenzyme (NAD+) regeneration only 5 % of L-methionine conversion can be achieved. This is the reason why three different regeneration methods were tested. The first one was NAD+ regeneration catalyzed by NADH oxidase from Lactobacillus brevis – relatively new and unstudied enzyme (Figure 1A). Using this regeneration method 100 % L-methionine conversion was achieved in the batch system. The second method was NAD+ regeneration in the pyruvate reduction catalyzed by L-lactate dehydrogenase from rabbit muscle (Figure 1B). 81 % L-methionine conversion was achieved using this regeneration system. The third regeneration method used was NAD+ regeneration in the phenylpyruvate reduction (Figure 1C) catalyzed by the same enzyme which catalyzes the main reaction (L-PheDH). Only 20 % of L-methionine was converted using this regeneration method.
Christopher R. Lowe - One of the best experts on this subject based on the ideXlab platform.
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Synthesis and properties of a naphthalene-containing artificial redox Coenzyme
Enzyme and Microbial Technology, 1997Co-Authors: Shahrzad Dilmaghanian, C. Vivian Stead, Richard J. Ansell, Christopher R. LoweAbstract:Abstract An analogue of the reactive triazine dye C.I. Reactive Blue 2 containing nicotinamide, Blue N-3, was shown previously to be coenzymically active with horse liver alcohol dehydrogenase (HLADH). 1,2 Blue N-3 contains an anthraquinone chromophore which is believed to mimic the adenine group of the natural Coenzyme NAD + , 3 but which gives rise to a strong absorption in the visible region of the spectrum. This, together with its relatively low solubility in water, has hindered the development of a simple spectrophotometric assay for monitoring its coenzymic activity and kinetics. Based on the knowledge that modifications to the adenine moiety of the natural Coenzyme NAD + do not greatly affect its coenzymic activity, 4 the blue anthraquinone chromophore of Blue N-3 was replaced with a terminal naphthalene group to yield the analogue Nap 1 ( Figure 1 ). This modification resulted in a markedly reduced molar extinction coefficient at 630 nm, increased water solubility, and an improved coenzymic performance. This paper describes the synthesis of Nap 1 and the characterization of its UV-visible absorption properties, pH stability, alcohol substrate specificity, electrochemical reversibility, and kinetic properties. These characteristics are compared and contrasted with those of Blue N-3 and NAD + .