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Osako, Takao; Nagatomo, Shigenori; Tachi, Yoshimitsu; Kitagawa, Teizo; Itoh, Shinobu

doi:10.1002/1521-3757(20021115)114:22<4501::aid-ange4501>3.0.co;2-t

Cited by 31 publications

(57 citation statements)

References 7 publications

(10 reference statements)

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“…4. Although the reaction mechanism between the copper(II) complex and H 2 O 2 have yet to be examined in detail, the reaction may proceeds via copper(II)-hydroperoxo intermediate E and copper(II)-peroxo intermediate F as demonstrated previously using the bis(2-pyridylethyl)amine ligands [23]. If so, the second-order kinetics suggest that the reaction of mononuclear copper(II)-peroxo intermediate F and another molecule of copper(II) starting material is the rate-determining step (see Scheme 2).…”

Section: Formation Of Bis(l-oxo)dicopper(iii) Complexesmentioning

confidence: 99%

A functional model for pMMO (particulate methane monooxygenase): Hydroxylation of alkanes with H2O2 catalyzed by β-diketiminatocopper(II) complexes

Shimokawa

Teraoka

Tachi

et al. 2006

Journal of Inorganic Biochemistry

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Section: Formation Of Bis(l-oxo)dicopper(iii) Complexesmentioning

confidence: 99%

A functional model for pMMO (particulate methane monooxygenase): Hydroxylation of alkanes with H2O2 catalyzed by β-diketiminatocopper(II) complexes

Shimokawa

Teraoka

Tachi

et al. 2006

Journal of Inorganic Biochemistry

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“…[1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19] Several types of mononuclear and dinuclear copper/active-oxygen complexes have been reported, and their structures and physicochemical properties have been explored in detail. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19] However, less is known about the intrinsic reactivity of the generated copper/ active-oxygen complexes.We herein report a new copper(II)-alkylperoxo species 2 X [2-hydroxy-2-hydroperoxypropane (HHPP) adduct], which is generated by the reaction of H 2 O 2 and copper(II) complex 1 X supported by the bis(pyridylmethyl)amine tridentate ligand containing msubstituted phenyl groups at the 6-positions of the pyridine rings (L X ) in acetone in the presence of triethylamine (NEt 3 ) (Scheme 1). The alkylperoxo intermediate 2 X undergoes an efficient aromatic ligand hydroxylation reaction, producing phenolate complex 4 X via another intermediate 3 X .…”

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confidence: 99%

Aromatic Hydroxylation Reactivity of a Mononuclear Cu(II)−Alkylperoxo Complex

et al. 2007

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The reactions of copper(II) complexes and hydrogen peroxide (H 2 O 2 ) have been studied extensively in order to gain insight into reactive intermediates involved in copper monooxygenases and copper oxidases as well as copper-catalyzed oxidation reactions. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19] Several types of mononuclear and dinuclear copper/active-oxygen complexes have been reported, and their structures and physicochemical properties have been explored in detail. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19] However, less is known about the intrinsic reactivity of the generated copper/ active-oxygen complexes.We herein report a new copper(II)-alkylperoxo species 2 X [2-hydroxy-2-hydroperoxypropane (HHPP) adduct], which is generated by the reaction of H 2 O 2 and copper(II) complex 1 X supported by the bis(pyridylmethyl)amine tridentate ligand containing msubstituted phenyl groups at the 6-positions of the pyridine rings (L X ) in acetone in the presence of triethylamine (NEt 3 ) (Scheme 1). The alkylperoxo intermediate 2 X undergoes an efficient aromatic ligand hydroxylation reaction, producing phenolate complex 4 X via another intermediate 3 X . Kinetic studies on the aromatic hydroxylation process are reported here together with spectral characterization of 2 X .Starting mononuclear copper(II) complexes 1 X supported by ligand L X (X ) NO 2 , Cl, H, Me, or OMe; Y ) ClO 4 -or H 2 O; S ) CH 3 CN or H 2 O) were prepared by mixing the ligands and Cu-(ClO 4 ) 2 ‚6H 2 O in acetone or acetonitrile (Figures S1-S4). 20 The reaction of 1 X and H 2 O 2 (1 equiv) was then examined in acetone at -70°C in the presence of triethylamine (1 equiv). Figure 1A shows a spectral change for the reaction of 1 NO 2 as a typical example, where intermediate 2 NO 2 exhibiting a characteristic absorption band at 420 nm ( ) 1350 M -1 cm -1 ) together with a weak d-d band at 630 nm ( ) 200 M -1 cm -1 ) becomes apparent. Spectroscopic titration for the generation of 2 NO 2 established that the stoichiometry of 1 NO 2 to H 2 O 2 was 1:1 ( Figure S5). Similar spectral changes were obtained with other ligand systems ( Figures S6-S9). A more detailed characterization of intermediate 2 X was carried out for 2 NO 2 since it showed higher stability than any other (as discussed further below).Intermediate 2 NO 2 generated with H 2 16 O 2 showed isotope sensitive Raman bands at 855, 823, 792, and 545 cm -1 when an acetone-d 6 (CD 3 COCD 3 ) solution of 2 NO 2 was excited with a 441.6 nm laser light ( Figure S10). These Raman bands shifted to 825, 803, 785, and 525 cm -1 , respectively, when H 2 18 O 2 was used ( Figure S10). The appearance of multiple Raman bands in the 800 cm -1 region and their associated isotope shifts (∆ν ) 30, 20, and 7 cm -1 ) as well as their intensity patterns are similar to those reported from resonance Raman studies of copper(II)-alkylperoxo (Cu II -OOR) and iron(III)-alkylperoxo (Fe III -OOR) complexes (R ) tert-butyl and cumyl), where such bands have been assigned as...

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“…Although no precedent exists for such a binding mode among non-heme copper proteins, the possibility of rearrangement of an end- on hydroperoxo ligand to a side-on coordination has been examined in small molecule model chemistry. The findings of low-temperature stopped-flow studies of the reaction of copper(II) complexes with H 2 O 2 [59] were interpreted as indicating that the initially formed end-on hydroperoxo ligand rearranges into a side-on peroxo ligand to give a copper(II)–peroxo complex. In bioinorganic chemistry there has been much interest in understanding how O 2 /H 2 O 2 -derived species interact with copper sites.…”

Section: Resultsmentioning

confidence: 99%

Coordination of peroxide to the CuM center of peptidylglycine α-hydroxylating monooxygenase (PHM): structural and computational study

et al. 2012

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Many bioactive peptides, such as hormones and neuropeptides, require amidation at the C terminus for their full biological activity. Peptidylglycine α-hydroxylating monooxygenase (PHM) performs the first step of the amidation reaction—the hydroxylation of peptidylglycine substrates at the Cα position of the terminal glycine. The hydroxylation reaction is copper- and O2-dependent and requires 2 equiv of exogenous reductant. The proposed mechanism suggests that O2 is reduced by two electrons, each provided by one of two nonequivalent copper sites in PHM (CuH and CuM). The characteristics of the reduced oxygen species in the PHM reaction and the identity of the reactive intermediate remain uncertain. To further investigate the nature of the key intermediates in the PHM cycle, we determined the structure of the oxidized form of PHM complexed with hydrogen peroxide. In this 1.98-Å-resolution structure (hydro)peroxide binds solely to CuM in a slightly asymmetric side-on mode. The O–O interatomic distance of the copper-bound ligand is 1.5 Å, characteristic of peroxide/hydroperoxide species, and the Cu–O distances are 2.0 and 2.1 Å. Density functional theory calculations using the first coordination sphere of the CuM active site as a model system show that the computed energies of the side-on L3CuM(II)–O22− species and its isomeric, end-on structure L3CuM(I)–O2·− are similar, suggesting that both these intermediates are significantly populated within the protein environment. This observation has important mechanistic implications. The geometry of the observed side-on coordinated peroxide ligand in L3CuM(II)O22− is in good agreement with the results of a hybrid quantum mechanical–molecular mechanical optimization of this species.

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Untitled

Cited by 31 publications

References 7 publications

A functional model for pMMO (particulate methane monooxygenase): Hydroxylation of alkanes with H2O2 catalyzed by β-diketiminatocopper(II) complexes

A functional model for pMMO (particulate methane monooxygenase): Hydroxylation of alkanes with H2O2 catalyzed by β-diketiminatocopper(II) complexes

Aromatic Hydroxylation Reactivity of a Mononuclear Cu(II)−Alkylperoxo Complex

Coordination of peroxide to the CuM center of peptidylglycine α-hydroxylating monooxygenase (PHM): structural and computational study

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