697-91-6Relevant articles and documents
Kinetic study of the oxidative dehalogenation of 2,4,6-trichlorophenol catalyzed by chloroperoxidase
Diaz-Diaz, Goretti,Blanco-Lopez, M. Carmen,Lobo-Castanon, M. Jesus,Miranda-Ordieres, Arturo J.,Tunon-Blanco, Paulino
, p. 332 - 336 (2010)
A sigmoidal behaviour of chloroperoxidase for the oxidative dehalogenation of 2,4,6-trichlorophenol is reported for the first time. Kinetic data were adjusted to the Hill equation and the kinetic parameters were obtained: n = 1.7±0.2, vmax =(8.8±0.3) × 10 -5Mmin-1, the pseudo-Michaelis constant Ks * = (8.6±0.5) × 10-5 M, kcat = 677±84min-1 and the catalytic efficiency = (8.9 ±0.6) × 106M-1 min-1. The sigmoidal curve could be related to the cooperative binding of the substrate to the enzyme, so that the binding of the first substrate molecule may help the binding of the second one. Further, both substrate molecules could establish Π-Π interactions between them, which would confer more stability to the system.
Nonphotochemical base-catalyzed hydroxylation of 2,6-dichloroquinone by H2O2 occurs by a radical mechanism
Franzen, Stefan,Sasan, Koroush,Sturgeon, Bradley E.,Lyon, Blake J.,Battenburg, Benjamin J.,Gracz, Hanna,Dumariah, Rania,Ghiladi, Reza
, p. 1666 - 1676 (2012)
Kinetic and structural studies have shown that peroxidases are capable of the oxidation of 2,4,6-trichlorophenol (2,4,6-TCP) to 2,6-dichloro-1,4- benzoquinone (2,6-DCQ). Further reactions of 2,6-DCQ in the presence of H 2O2 and OH- yield 2,6-dichloro-3-hydroxy-1,4- benzoquinone (2,6-DCQOH). The reactions of 2,6-DCQ have been monitored spectroscopically [UV-visible and electron spin resonance (ESR)] and chromatographically. The hydroxylation product, 2,6-DCQOH, has been observed by UV-visible and characterized structurally by 1H and 13C NMR spectroscopy. The results are consistent with a nonphotochemical base-catalyzed oxidation of 2,6-DCQ at pH > 7. Because H2O 2 is present in peroxidase reaction mixtures, there is also a potential role for the hydrogen peroxide anion (HOO-). However, in agreement with previous work, we observe that the nonphotochemical epoxidation by H2O2 at pH 2O2 at low pH). Analysis of the kinetics using an Arrhenius model permits determination of the activation energy of hydroxylation (Ea = 36 kJ/mol), which is significantly lower than the activation energy of the peroxidase-catalyzed oxidation of 2,4,6-TCP (Ea = 56 kJ/mol). However, the reaction is second order in both 2,6-DCQ and OH - so that its rate becomes significant above 25 °C due to the increased rate of formation of 2,6-DCQ that feeds the second-order process. The peroxidase used in this study is the dehaloperoxidase-hemoglobin (DHP A) from Amphitrite ornata, which is used to study the effect of a catalyst on the reactions. The control experiments and precedents in studies of other peroxidases lead to the conclusion that hydroxylation will be observed following any process that leads to the formation of the 2,6-DCQ at pH > 7, regardless of the catalyst used in the 2,4,6-TCP oxidation reaction.
C. fumago chloroperoxidase is also a dehaloperoxidase: Oxidative dehalogenation of halophenols
Osborne, Robert L.,Raner, Gregory M.,Hager, Lowell P.,Dawson, John H.
, p. 1036 - 1037 (2006)
We have examined the H2O2-dependent oxidative dehalogenation of 2,4,6-trihalophenols and p-halophenols catalyzed by Caldariomyces fumago chloroperoxidase (CCPO). CCPO is significantly more robust than other peroxidases and can function under harsher reaction conditions, and so its ability to dehalogenate halophenols could lead to its use as a bioremediation catalyst for aromatic dehalogenation reactions. Optimal catalysis occurred under acidic conditions (100 mM potassium phosphate solution, pH 3.0). UV-visible absorption spectroscopy, high-performance liquid chromatography, and gas chromatography/mass spectrometry clearly identified the oxidized reaction product for CCPO-catalyzed dehalogenation of 2,4,6-trihalophenols as the corresponding 2,6-dihalo-1,4-benzoquinones. This reaction has previously been reported for two His-ligated heme-containing peroxidases (see Osborne, R. L.; Taylor, L. O.; Han, K. P.; Ely, B.; Dawson, J. H. Biochem. Biophys. Res. Commun. 2004, 324, 1194-1198), but this is the first example of a Cys-ligated heme-containing peroxidase functioning as a dehaloperoxidase. The relative catalytic efficiency (turnover number) of CCPO reported herein is comparable to that of horseradish peroxidase (Ferrari, R. P.; Laurenti, E.; Trotta, F. J. Biol. Inorg. Chem. 1965, 4, 232-237). The mechanism of dehalogenation has been probed using p-halophenols as substrates. Here the major product is a dimer with 1,4-benzoquinone as the minor product. An electron-transfer mechanism is proposed that accounts for the products formed from both the 2,4,6-trihalo- and p-halophenols. Finally, we note that this is the first case of a peroxidase known primarily for its halogenation ability being shown to also dehalogenate substrates. Copyright
Determination of separate inhibitor and substrate binding sites in the dehaloperoxidase-hemoglobin from Amphitrite ornata
Davis, Michael F.,Bobay, Benjamin G.,Franzen, Stefan
, p. 1199 - 1206 (2010)
Dehaloperoxidase-hemoglobin (DHP A) is a dual function protein found in the terrebellid polychaete Amphitrite ornata. A. ornata is an annelid, which inhabits estuary mudflats with other polychaetes that secrete a range of toxic brominated phenols. DHPA is capable of binding and oxidatively dehalogenating some of these compounds. DHP A possesses the ability to bind halophenols in a distinct, internal distal binding pocket. Since its discovery, the distal binding pocket has been reported as the sole binding location for halophenols; however, data herein suggest a distinction between inhibitor (monohalogenated phenol) and substrate (trihalogenated phenol) binding locations. Backbone 13Cα, 13Cβ, carbonyl 13C, amide 1H, and amide 15N resonance assignments have been made, and various halophenols were titrated into the protein. 1H- 15N HSQC experiments were collected at stoichiometric intervals during each titration, and binding locations specific for mono- and trihalogenated phenols have been identified. Titration of monohalogenated phenol induced primary changes around the distal binding pocket, while introduction of trihalogenated phenols created alterations of the distal histidine and the local area surrounding W120, a structural region that corresponds to a possible dimer interface region recently observed in X-ray crystal structures of DHP A. 2010 American Chemical Society.
Photophysical and photocatalytic properties of β-sulfonatoporphycenes
Baba, Tatsushi,Shimakoshi, Hisashi,Endo, Ayataka,Adachi, Chihaya,Hisaeda, Yoshio
, p. 264 - 265 (2008)
The photophysical properties and photooxidation ability of the β-sulfonatoporphycenes are reported. The photophysical parameters depend on the number of substitutions. The disulfonated porphycene 2 is expected to be a new photosensitizer due to its high catalytic activity and photostability. Copyright
Conversion of Human Neuroglobin into a Multifunctional Peroxidase by Rational Design
Chen, Shun-Fa,Liu, Xi-Chun,Xu, Jia-Kun,Li, Lianzhi,Lang, Jia-Jia,Wen, Ge-Bo,Lin, Ying-Wu
, p. 2839 - 2845 (2021/02/16)
Protein design has received much attention in the last decades. With an additional disulfide bond to enhance the protein stability, human A15C neuroglobin (Ngb) is an ideal protein scaffold for heme enzyme design. In this study, we rationally converted A15C Ngb into a multifunctional peroxidase by replacing the heme axial His64 with an Asp residue, where Asp64 and the native Lys67 at the heme distal site were proposed to act as an acid-base catalytic couple for H2O2 activation. Kinetic studies showed that the catalytic efficiency of A15C/H64D Ngb was much higher (~50-80-fold) than that of native dehaloperoxidase, which even exceeds (~3-fold) that of the most efficient native horseradish peroxidase. Moreover, the dye-decolorizing peroxidase activity was also comparable to that of some native enzymes. Electron paramagnetic resonance, molecular docking, and isothermal titration calorimetry studies provided valuable information for the substrate-protein interactions. Therefore, this study presents the rational design of an efficient multifunctional peroxidase based on Ngb with potential applications such as in bioremediation for environmental sustainability.
Electrochemical chlorination and bromination of electron-deficient C[sbnd]H bonds in quinones, coumarins, quinoxalines and 1,3-diketones
Yu, Dan,Ji, Ruixue,Sun, Zhihui,Li, Wenjie,Liu, Zhong-Quan
supporting information, (2021/11/16)
The electrochemistry-promoted chlorination and bromination of electron-deficient C[sbnd]H bonds was developed, using quinones, coumarins, quinoxalines and 1,3-diketones. This protocol features readily available and safe halogen sources (hydrochloric acid and KBr), high site-selectivity and mild reaction conditions. It could provide an efficient access to a series of chlorinated and brominated quinones, coumarins, quinoxalines and 1,3-diketones.