Intradiol Aromatic Ring Cleavage in a Dioxygenase Model System

1981 ◽  
Vol 36 (10) ◽  
pp. 1324-1330 ◽  
Author(s):  
Dennis G. Brown ◽  
William J. Hughes
Keyword(s):  
Oxygen Consumption ◽  
Model System ◽  
Oxidation Products ◽  
Ring Cleavage ◽  
Secondary Oxidation ◽  
Isomeric Mixture ◽  
Aromatic Ring Cleavage ◽  
Phenanthroline Ligand ◽  
Kinetics Of

Abstract Dioxygenase Model, Copper, Catechol The complex (3-n-nonylcatecholato)(1,10-phenanthroline)copper(II) reacts with molecular oxygen to give an isomeric mixture of 2-n-nonylmuconic acid and several secondary oxidation products. The catecholato ligand is oxidatively cleaved in an intradiol fashion reminescent of the reactions catalyzed by intradiol aromatic dioxygenases. The 1,10-phenanthroline ligand can be quantitatively recovered and is not oxidized. In addition to characterization of oxidation products, the kinetics of oxygen consumption have been analyzed. The rate law for oxygen uptake is -d[O2]/dt = k[O2] [copper]2 .

scholarly journals Degradation of 2,4,6-Trichlorophenol by Phanerochaete chrysosporium: Involvement of Reductive Dechlorination

1998 ◽  
Vol 180 (19) ◽  
pp. 5159-5164 ◽  
Author(s):  
G. Vijay Bhasker Reddy ◽  
Maarten D. Sollewijn Gelpke ◽  
Michael H. Gold
Keyword(s):  
Phanerochaete Chrysosporium ◽  
Reductive Dechlorination ◽  
Oxidation Products ◽  
Ring Cleavage ◽  
Fungal Metabolites ◽  
Subsequent Degradation ◽  
Metabolic Conditions ◽  
The Common ◽  
Dechlorination Reaction

ABSTRACT Under secondary metabolic conditions, the lignin-degrading basidiomycete Phanerochaete chrysosporium mineralizes 2,4,6-trichlorophenol. The pathway for the degradation of 2,4,6-trichlorophenol has been elucidated by the characterization of fungal metabolites and oxidation products generated by purified lignin peroxidase (LiP) and manganese peroxidase (MnP). The multistep pathway is initiated by a LiP- or MnP-catalyzed oxidative dechlorination reaction to produce 2,6-dichloro-1,4-benzoquinone. The quinone is reduced to 2,6-dichloro-1,4-dihydroxybenzene, which is reductively dechlorinated to yield 2-chloro-1,4-dihydroxybenzene. The latter is degraded further by one of two parallel pathways: it either undergoes further reductive dechlorination to yield 1,4-hydroquinone, which isortho-hydroxylated to produce 1,2,4-trihydroxybenzene, or is hydroxylated to yield 5-chloro-1,2,4-trihydroxybenzene, which is reductively dechlorinated to produce the common key metabolite 1,2,4-trihydroxybenzene. Presumably, the latter is ring cleaved with subsequent degradation to CO2. In this pathway, the chlorine at C-4 is oxidatively dechlorinated, whereas the other chlorines are removed by a reductive process in which chlorine is replaced by hydrogen. Apparently, all three chlorine atoms are removed prior to ring cleavage. To our knowledge, this is the first reported example of aromatic reductive dechlorination by a eukaryote.

scholarly journals Inhibition of Corn Oil Peroxidation by Extracts from Defatted Seeds of Camellia oleifera Abel

2017 ◽  
Vol 2017 ◽  
pp. 1-7
Author(s):  
Haiming Chen ◽  
Fei Song ◽  
Weijun Chen ◽  
Wenxue Chen
Keyword(s):  
Phenolic Compounds ◽  
Corn Oil ◽  
Oxidation Products ◽  
Total Phenolic ◽  
Camellia Oleifera ◽  
Secondary Oxidation ◽  
Quantitative Characterization ◽  
Qualitative And Quantitative ◽  
Seed Extracts

The defatted seed of Camellia oleifera Abel is an underexploited byproduct. In the present study, 3 solvents (isopropanol, hexane, and diethyl ether) were used to extract active compounds from defatted seeds of Camellia oleifera Abel. The qualitative and quantitative characterization of the main phenolic compounds were performed using the HPLC-DAD. In addition, the antioxidant efficacy of defatted seed extracts in the stabilization of the corn oil was estimated by monitoring its primary and secondary oxidation products. The results showed that isopropanolic extract (IE) exhibited the highest yield of total phenolic compounds (9.23±0.33 mg/g) compared with other solvents. The predominant phenolic compounds identified by HPLC-DAD in defatted seed extracts were epicatechin, naringenin, and catechin. In addition, IE exhibited the best inhibition effect on both primary and secondary oxidation products. The results reveal that IE of defatted seed of Camellia oleifera Abel is a useful antioxidant for the stabilization of corn oil.

Cloning and characterization of extradiol aromatic ring-cleavage dioxygenases of Pseudomonas aeruginosa JI104

1996 ◽  
Vol 82 (3) ◽  
pp. 217-223 ◽  
Author(s):  
Atsushi Kitayama ◽  
Tomohisa Achioku ◽  
Takahiro Yanagawa ◽  
Kenjiro Kanou ◽  
Masako Kikuchi ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Aromatic Ring ◽  
Ring Cleavage ◽  
Aromatic Ring Cleavage

scholarly journals Structural characterization of 2,6-dichloro-p-hydroquinone 1,2-dioxygenase (PcpA) fromSphingobium chlorophenolicum, a new type of aromatic ring-cleavage enzyme

2013 ◽  
Vol 88 (3) ◽  
pp. 523-536 ◽  
Author(s):  
Robert P. Hayes ◽  
Abigail R. Green ◽  
Mark S. Nissen ◽  
Kevin M. Lewis ◽  
Luying Xun ◽  
...  
Keyword(s):  
Aromatic Ring ◽  
Structural Characterization ◽  
Ring Cleavage ◽  
Cleavage Enzyme ◽  
New Type ◽  
Aromatic Ring Cleavage

Irradiation behavior of pyrolytic silicon carbide

1983 ◽  
Vol 41 ◽  
pp. 72-73
Author(s):  
R. J. Lauf
Keyword(s):  
Silicon Carbide ◽  
Fission Products ◽  
Thermodynamics And Kinetics ◽  
Neutron Fluences ◽  
Fuel Particles ◽  
Sic Coatings ◽  
Irradiation Behavior ◽  
Kinetics Of ◽  
Htgr Fuel

Fuel particles for the High-Temperature Gas-Cooled Reactor (HTGR) contain a layer of pyrolytic silicon carbide to act as a miniature pressure vessel and primary fission product barrier. Optimization of the SiC with respect to fuel performance involves four areas of study: (a) characterization of as-deposited SiC coatings; (b) thermodynamics and kinetics of chemical reactions between SiC and fission products; (c) irradiation behavior of SiC in the absence of fission products; and (d) combined effects of irradiation and fission products. This paper reports the behavior of SiC deposited on inert microspheres and irradiated to fast neutron fluences typical of HTGR fuel at end-of-life.

Prolonged Kinetics of Recovery of Oxygen Consumption After Maximal Graded Exercise in Patients With Chronic Heart Failure

Circulation ◽  
1995 ◽  
Vol 91 (12) ◽  
pp. 2924-2932 ◽  
Author(s):  
Alain Cohen-Solal ◽  
Thierry Laperche ◽  
Daniel Morvan ◽  
Michel Geneves ◽  
Bernard Caviezel ◽  
...  
Keyword(s):  
Heart Failure ◽  
Oxygen Consumption ◽  
Chronic Heart Failure ◽  
Graded Exercise ◽  
Kinetics Of

Elaboration and Characterization of the Properties of Refractory Cr Base Alloys

2010 ◽  
Vol 72 ◽  
pp. 46-52 ◽  
Author(s):  
Laurent Royer ◽  
Stéphane Mathieu ◽  
Christophe Liebaut ◽  
Pierre Steinmetz
Keyword(s):  
Mechanical Properties ◽  
Melting Point ◽  
Molten Glass ◽  
Energy Production ◽  
Creep Properties ◽  
Refractory Alloys ◽  
Industrial Use ◽  
Kinetics Of ◽  
Selection Of

For energy production and also for the glass industry, finding new refractory alloys which could permit to increase the process temperatures to 1200°C or more is a permanent challenge. Chromium base alloys can be good candidates, considering the melting point of Cr itself, and also its low corrosion rate in molten glass. Two families of alloys have been studied for this purpose, Cr-Mo-W and Cr-Ta-X alloys (X= Mo, Si..). A finer selection of compositions has been done, to optimize their chemical and mechanical properties. Kinetics of HT oxidation by air, of corrosion by molten glass and also creep properties of several alloys have been measured up to 1250°C. The results obtained with the best alloys (Cr-Ta base) give positive indications as regards the possibility of their industrial use.

scholarly journals New Trimethoprim-Like Molecules: Bacteriological Evaluation and Insights into Their Action

Antibiotics ◽  
2021 ◽  
Vol 10 (6) ◽  
pp. 709
Author(s):  
Marta Jorba ◽  
Marina Pedrola ◽  
Ouldouz Ghashghaei ◽  
Rocío Herráez ◽  
Lluis Campos-Vicens ◽  
...  
Keyword(s):  
Inhibitory Concentration ◽  
Efflux Pump ◽  
Synergistic Effects ◽  
Nicotinamide Adenine Dinucleotide Phosphate ◽  
Detailed Characterization ◽  
Low Concentrations ◽  
Pump Activity ◽  
Bacteriological Evaluation ◽  
Kinetics Of

This work reports a detailed characterization of the antimicrobial profile of two trimethoprim-like molecules (compounds 1a and 1b) identified in previous studies. Both molecules displayed remarkable antimicrobial activity, particularly when combined with sulfamethoxazole. In disk diffusion assays on Petri dishes, compounds 1a and 1b showed synergistic effects with colistin. Specifically, in combinations with low concentrations of colistin, very large increases in the activities of compounds 1a and 1b were determined, as demonstrated by alterations in the kinetics of bacterial growth despite only slight changes in the fractional inhibitory concentration index. The effect of colistin may be to increase the rate of antibiotic entry while reducing efflux pump activity. Compounds 1a and 1b were susceptible to extrusion by efflux pumps, whereas the inhibitor phenylalanine arginyl β-naphthylamide (PAβN) exerted effects similar to those of colistin. The interactions between the target enzyme (dihydrofolate reductase), the coenzyme nicotinamide adenine dinucleotide phosphate (NADPH), and the studied molecules were explored using enzymology tools and computational chemistry. A model based on docking results is reported.

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