Journal ArticleDOI
The catalytic cycle of catechol oxidase
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TLDR
Hybrid density functional theory with the B3LYP functional has been used to investigate the catalytic mechanism of catechol oxidase, and the calculated energetics is in reasonable agreement with experiments.Abstract:
Hybrid density functional theory with the B3LYP functional has been used to investigate the catalytic mechanism of catechol oxidase. Catechol oxidase belongs to a class of enzymes that has a copper dimer with histidine ligands at the active site. Another member of this class is tyrosinase, which has been studied by similar methods previously. An important advantage for the present study compared to the one for tyrosinase is that X-ray crystal structures exist for catechol oxidase. The most critical step in the mechanism for catechol oxidase is where the peroxide O–O bond is cleaved. In the suggested mechanism this cleavage occurs in concert with a proton transfer from the substrate. Shortly after the transition state is passed there is another proton transfer from the substrate, which completes the formation of a water molecule. An important feature of the mechanism, like the one for tyrosinase, is that no proton transfers to or from residues outside the metal complex are needed. The calculated energetics is in reasonable agreement with experiments. Comparisons are made to other similar enzymes studied previously.read more
Citations
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Quantum chemical studies of mechanisms for metalloenzymes.
TL;DR: The most often encountered reaction of the Fe(III)−O2 species is an electrophilic attack on an electron-rich (co)substrate that yields an Fe(II) intermediate with a peroxide bridge between the ferrous ion and an organic molecule (Figure 57).
Journal ArticleDOI
Synthetic models of the active site of catechol oxidase: mechanistic studies
TL;DR: This critical review extensively discusses the synthetic models of catechol oxidase, with a particular emphasis on the different approaches used in the literature to study the mechanism of the catalytic oxidation of the substrate (catechol) by these compounds.
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Catechol oxidase and phenoxazinone synthase: Biomimetic functional models and mechanistic studies
Suman Kr Dey,Arindam Mukherjee +1 more
TL;DR: The biomimetic studies strongly suggest that among the various metal ions probed for modeling the catalytic activity of CO and PHS, MnII/III based systems are so far the most promising candidates apart from the nature's choice CuII.
Journal ArticleDOI
Copper-Promoted Functionalization of Organic Molecules: from Biologically Relevant Cu/O2 Model Systems to Organometallic Transformations
TL;DR: The most relevant research in which copper promotes or catalyzes the functionalization of organic molecules, including biological catalysis, bioinspired model systems, and organometallic reactivity is summarized.
Journal ArticleDOI
Catechol oxidase activity of a series of new dinuclear copper(II) complexes with 3,5-DTBC and TCC as substrates: syntheses, X-ray crystal structures, spectroscopic characterization of the adducts and kinetic studies.
Kazi Sabnam Banu,Tanmay Chattopadhyay,Arpita Banerjee,Santanu Bhattacharya,Eringathodi Suresh,M. Nethaji,Ennio Zangrando,Debasis Das +7 more
TL;DR: 1 is observed to be effective even in TCC oxidation, a process never reported earlier, and a treatment on the basis of Michaelis-Menten model has been applied for kinetic study, suggesting that all five complexes exhibit very high turnover number.
References
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Kinetic, thermodynamic, and spectral characterization of the primary copper-oxygen (Cu-O2) adduct in a reversibly formed and structurally characterized peroxo-dicopper(II) complex
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Reversible dioxygen binding to hemerythrin.
TL;DR: The calculated total O(2) binding free energy is in good agreement with that derived from the experimental equilibrium constant.
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The catalytic cycle of tyrosinase: peroxide attack on the phenolate ring followed by O-O bond cleavage
TL;DR: The oxidation of phenols to ortho-quinones, catalyzed by tyrosinase, has been studied using the hybrid DFT method B3LYP and a preliminary investigation was made, indicating a few problems which require future QM/MM studies.
Theoretical Study of the Interconversion of O2 Binding Dicopper Complexes
Michaela Flock,Kristine Pierloot +1 more
TL;DR: In this article, the structures and interconversion pathway between the [Cu2(μ-η2: η2-O2)]2+ and [Cu 2(μ)-O)2]2+ isomers of model systems with three ammonia ligands per copper center are investigated using both density functional theory with a B3LYP functional (B3LY P-DFT) and multiconfigurational perturbation theory (CASSCF/CASPT2).
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Phenolase and Pectic Enzyme Activity in the Chocolate Spot Disease of Beans
TL;DR: In this article, it was found that the latent phenolase of bean leaves could be activated by certain pectic substances and by a soluble cellulose derivative in a way similar to that described by Kenten1 for anionic wetting agents.