Resonance Raman evidence for tyrosine involvement in the radical site of galactose oxidase

Whittaker, Mei M.; DeVito, Valentino L.; Asher, Sanford A.; Whittaker, James W.

doi:10.1016/s0021-9258(18)83205-7

Cited by 111 publications

(49 citation statements)

References 16 publications

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“…Mononuclear Schiff-base complexes are important in modelling metallobioenzymes [1][2][3][4] as well as from the industrial perspective. 5 As a result, a great deal of research attention has been paid to understanding the reactivity of metalloradicals involved in free radical catalysis, such as galactose oxidase (GOase), [6][7][8] along with some industrially important catalytic reactions, such as oxidative coupling polymerization of phenol derivatives, 9 oxidation of hydrocarbons, [10][11][12][13] etc., which provides an environmentally benign method. Soil and sediment bacteria like Pseudomonas putida are the most extensively characterized catabolic plasmid that encodes enzymes for the mineralization of toluene, m-and p-xylenes, m-ethyl-toluene and 1,3,4-trimethylbenzene 14,15 in which the methyl group at carbon-1 in the aromatic ring is sequentially oxidized in a number of steps to give pyruvate and aldehydes as the nal products.…”

Section: Introductionmentioning

confidence: 99%

Copper(ii) induced oxidative modification and complexation of a schiff base ligand: synthesis, crystal structure, catalytic oxidation of aromatic hydrocarbons and DFT calculation

et al. 2014

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Section: Introductionmentioning

confidence: 99%

Copper(ii) induced oxidative modification and complexation of a schiff base ligand: synthesis, crystal structure, catalytic oxidation of aromatic hydrocarbons and DFT calculation

et al. 2014

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“…[32][33][34] Recently it has been observed that many transition-metal complexes, in combination with various oxidizing agents, can catalyze the oxidation of a variety of hydrocarbons including lower alkanes. 35 Monomeric copper-Schiff base complexes are important in modelling metallobioenzymes [36][37][38][39] as well as from the industrial perspective 40 and a great amount of research attention has been paid to understand the reactivity of metalloradicals involved in free-radical catalysis such as GOase [41][42][43] along with some industrially important catalytic reactions such as oxidative coupling polymerization of phenol derivatives, 44 oxidation of hydrocarbons [45][46][47][48] etc., which provide an environmentally benign method. Though, copper-Schiff base compounds have been widely used as catalysts in oxidation of hydrocarbons, yields and TON (turn over number) obtained are not very remarkable so far.…”

Section: Introductionmentioning

confidence: 99%

A novel thermally stable hydroperoxo–copper(ii) complex in a Cu(N2O2) chromophore of a potential N4O2 donor Schiff base ligand: synthesis, structure and catalytic studies

et al. 2013

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The generation and study of metal-hydroperoxo/metal-peroxo (LCu(II)-OOH or LCu(II)-OO˙) complexes is a fascinating area of research of many chemical and biochemical researchers, because of their involvement as active intermediates in many biological and industrial catalytic oxidation processes. For this purpose we have designed a bulky hexa-coordinating ligand with potential N4O2 donor atoms which could provide an opportunity to synthesize a mononuclear Cu(II) complex with an aim to utilize it in the catalytic oxidation of aromatic hydrocarbons by an environmentally benign oxidant, H2O2. The Cu(II) complex (1) was structurally characterized and found to have square-planar geometry with the two pyrazolyl groups remaining in dangling mode. A novel mononuclear complex [Et3NH][LCu(II)-OOH] (2) was found to form in the reaction between 1 and H2O2 in the presence of Et3N. The presence of this dangling groups favours the stability of hydroperoxo species, [LCu-OOH](-) (2) through H-bonding with the coordinated phenoxo oxygen atom, which was confirmed by ESI-MS(+) and MS(-) (m/z) mass analysis and DFT calculations. This complex was found to be thermally stable at room temperature [k(d) = (5.67 ± 0.03) × 10(-5) s(-1) at 25 °C] and may be due to the formation of O-O-H···O(phenoxo) H-bonding as delineated by the DFT calculations. Complex 1 was found to be an efficient catalyst for the oxidation of aromatic hydrocarbons to the corresponding aldehyde and alcohol in 2:1 mole ratio with TON ~300.

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“…This assumption is, however, incorrect. Recent studies show that the copper ion occurs in its divalent state, Cu 2+, which is antiferromagnetically coupled to a tyrosyl radical (Tyr272) and is, therefore, ESR-inactive [158].…”

Section: Structurementioning

confidence: 99%

Evolutionary aspects of copper binding centers in copper proteins

Abolmaali

Taylor

Weser

Structure and Bonding

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A great number of active centers in proteins and enzymes contain transition metals. Each metal imposes specific catalytic properties on the protein which could not be achieved when employing a different metal. The special role and characteristic reactivity of coordinated copper is illustrated by looking at the evolutionary aspects of copper proteins. The evolution of copper-binding sites is closely linked to that of copper proteins. Copper centers have evolved according to various principles, similar to the evolutionary development of proteins and enzymes. Three basic principles may be observed: the copper-binding centers of metallothioneins and type 1 copper centers developed in non-metal proteins; the transformation of the metal-binding centers of iron or manganese proteins led to the development of the type 2 copper centers; and the trinuclear copper-binding centers of the blue oxidases were formed by alterations and recombinations of type 1 copper centers. Simple, although as yet unknown, mononuclear copper centers gave rise to the type 3 copper-binding sites of the hemocyanins and tyrosinases, as well as to the Cu A-and CUB-centers of the cytochrome oxidases and N20reductase. According to this assignment, copper proteins containing either type 1 copper, type 3 copper, CUA-centers, or CUB-centers share a common ancestor. They developed at least in part by divergent evolution. Type 2 copper proteins are the products of convergent evolution and, consequently, show little or no phylogenetic homology.

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Resonance Raman evidence for tyrosine involvement in the radical site of galactose oxidase

Cited by 111 publications

References 16 publications

Copper(ii) induced oxidative modification and complexation of a schiff base ligand: synthesis, crystal structure, catalytic oxidation of aromatic hydrocarbons and DFT calculation

Copper(ii) induced oxidative modification and complexation of a schiff base ligand: synthesis, crystal structure, catalytic oxidation of aromatic hydrocarbons and DFT calculation

A novel thermally stable hydroperoxo–copper(ii) complex in a Cu(N2O2) chromophore of a potential N4O2 donor Schiff base ligand: synthesis, structure and catalytic studies

Evolutionary aspects of copper binding centers in copper proteins

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