Amine Oxidase and Galactose Oxidase

Rokhsana, Dalia; Shepard, Eric M.; Brown, Doreen E.; Dooley, David M.

doi:10.1002/9781118094365.ch3

Cited by 20 publications

(41 citation statements)

References 155 publications

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“…Likewise, as mentioned above, rate-limiting HAT occurs for the galactose oxidase (GO) active-site special Tyr, but PCET in copper amine oxidase (CAO) has been suggested by Klinman 7c and Roth. 8 In relevant C-H bond activation by [Cu II (O 2 ˙ − )] + species, Klinman and Blackburn reported C-H bond cleavage in N -benzoylglycine by PHM having large intrinsic isotope effects.…”

Section: Resultsmentioning

confidence: 87%

“…11 As is relevant to part of the GO catalytic cycle, recent experimental studies support a mechanism wherein O 2 -binding to this fully reduced copper ion affords a cupric superoxo species (Figure 1) and that this mediates the oxidation of the ligated tyrosine residue resulting in the formation of a cupric hydroperoxide species ( C ) plus phenoxyl radical. 7c Hydrolysis leads to the release of hydrogen peroxide, the observed stoichiometric O 2 reduction product in the overall mechanism.…”

Section: Introductionmentioning

confidence: 99%

“…6a,8 From relatively recent experimental and computational studies, the [Cu II (O 2 ˙ − )] + ( A or B ) moiety has been declared as the reactive intermediate which effects C–H 9,10 or O–H 7,8 hydrogen-atom transfer (HAT) reactions. Relevant to this is an X-ray crystallographic study on a PHM derivative, which reveals a dioxygen-derived species assigned as an endon bound cupric superoxo species ( B ) (also discussion below).…”

Section: Introductionmentioning

confidence: 99%

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Mechanistic Insights into the Oxidation of Substituted Phenols via Hydrogen Atom Abstraction by a Cupric–Superoxo Complex

et al. 2014

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To obtain mechanistic insights into the inherent reactivity patterns for copper(I)–O2 adducts, a new cupric–superoxo complex [(DMM-tmpa)CuII(O2•–)]+ (2) [DMM-tmpa = tris((4-methoxy-3,5-dimethylpyridin-2-yl)methyl)amine] has been synthesized and studied in phenol oxidation–oxygenation reactions. Compound 2 is characterized by UV–vis, resonance Raman, and EPR spectroscopies. Its reactions with a series of para-substituted 2,6-di-tert-butylphenols (p-X-DTBPs) afford 2,6-di-tert-butyl-1,4-benzoquinone (DTBQ) in up to 50% yields. Significant deuterium kinetic isotope effects and a positive correlation of second-order rate constants (k2) compared to rate constants for p-X-DTBPs plus cumylperoxyl radical reactions indicate a mechanism that involves rate-limiting hydrogen atom transfer (HAT). A weak correlation of (kBT/e) ln k2 versus Eox of p-X-DTBP indicates that the HAT reactions proceed via a partial transfer of charge rather than a complete transfer of charge in the electron transfer/proton transfer pathway. Product analyses, 18O-labeling experiments, and separate reactivity employing the 2,4,6-tri-tert-butylphenoxyl radical provide further mechanistic insights. After initial HAT, a second molar equiv of 2 couples to the phenoxyl radical initially formed, giving a CuII–OO–(ArO′) intermediate, which proceeds in the case of p-OR-DTBP substrates via a two-electron oxidation reaction involving hydrolysis steps which liberate H2O2 and the corresponding alcohol. By contrast, four-electron oxygenation (O–O cleavage) mainly occurs for p-R-DTBP which gives 18O-labeled DTBQ and elimination of the R group.

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Section: Resultsmentioning

confidence: 87%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Mechanistic Insights into the Oxidation of Substituted Phenols via Hydrogen Atom Abstraction by a Cupric–Superoxo Complex

et al. 2014

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“…[10] These cofactors, a tyrosine covalently cross-linked to a cysteine (Tyr-Cys) in GO and 2,4,5-trihy-droxyphenylalanine quinone (TPQ) in AO, are post-translationally derived.…”

Section: Enzymatic Systems Involving Cuii(o2•−)mentioning

confidence: 99%

“…These enzymes include the noncoupled binuclear enzymes peptidylglycine α-hydroxylating monooxygenase (PHM), [6,7] dopamine-β-monooxygenase (DβM), [6,7] and tyramine-β-monooxygenase (TβM), [7] and the mononuclear enzymes lytic polysaccharide monooxygenases (LPMOs), [8,9] galactose oxidase (GO), [10] and copper amine oxidases (AOs). [10] …”

Section: Introductionmentioning

confidence: 99%

Copper(I)‐Dioxygen Adducts and Copper Enzyme Mechanisms

Liu

Díaz

Quist

et al. 2016

Israel Journal of Chemistry

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Primary copper(I)-dioxygen (O2) adducts, cupric-superoxide complexes, have been proposed intermediates in copper-containing dioxygen-activating monooxygenase and oxidase enzymes. Here, mechanisms of C–H activation by reactive copper-(di)oxygen intermediates are discussed, with an emphasis on cupric-superoxide species. Over the past 25 years, many synthetically derived cupric-superoxide model complexes have been reported. Due to the thermal instability of these intermediates, early studies focused on increasing their stability and obtaining physical characterization. More recently, in an effort to gain insight into the possible substrate oxidation step in some copper monooxygenases, several cupric-superoxide complexes have been used as surrogates to probe substrate scope and reaction mechanisms. These cupric superoxides are capable of oxidizing substrates containing weak O–H and C–H bonds. Mechanistic studies for some enzymes and model systems have supported an initial hydrogen-atom abstraction via the cupric-superoxide complex as the first step of substrate oxidation.

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Copper Peroxide Bioinorganic Chemistry: From Metalloenzymes to Bioinspired Synthetic Systems

Garcia‐Bosch

Karlin

2014

Patai's Chemistry of Functional Groups

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During the last few decades, copper‐dioxygen chemistry has emerged as a new and very active field of (bio)inorganic relevance. Highlighted herein are the major findings, including the principles of dioxygen activation in metal‐containing proteins along with characterization and reactivity of natural copper‐peroxo systems which are derived from reaction of molecular oxygen with copper(I) active‐site centers. Inspired by the varied array of copper proteins‐enzymes which have been characterized, synthetic bioinorganic researchers have developed model systems which are amenable to facilitating the electron‐transfer and atom‐transfer chemistry which pervades dioxygen binding to copper complexes found in various oxidation states (+1 to +3). These studies have provided for new coordination chemistry of fundamental importance. In addition, significant contributions concerning the identity of biological or chemical reactive intermediates and insights into copper enzyme reaction mechanisms have been made. Taking advantage of this rich redox chemistry, synthetic methods combining copper and O2 (or H2O2) have been explored by organic/inorganic chemists, seeking to employ this earth abundant element to replace routes now usually carried out with precious (expensive/non‐benign) metals, developing green, sustainable and selective oxidative processes.

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Amine Oxidase and Galactose Oxidase

Cited by 20 publications

References 155 publications

Mechanistic Insights into the Oxidation of Substituted Phenols via Hydrogen Atom Abstraction by a Cupric–Superoxo Complex

Mechanistic Insights into the Oxidation of Substituted Phenols via Hydrogen Atom Abstraction by a Cupric–Superoxo Complex

Copper(I)‐Dioxygen Adducts and Copper Enzyme Mechanisms

Copper Peroxide Bioinorganic Chemistry: From Metalloenzymes to Bioinspired Synthetic Systems

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