The Crystal Structure of Catechol Oxidase:  New Insight into the Function of Type-3 Copper Proteins

Gerdemann, Carsten; Eicken, Christoph; Krebs, Bernt

doi:10.1021/ar990019a

Cited by 536 publications

(366 citation statements)

References 39 publications

(156 reference statements)

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“…In contrast, the catechol oxidase active site is, similar to tyrosinase and hemocyanin, a type 3 copper center [2,9,11,12,57]. That is, the copper centers are in nitrogen-rich coordination environments and are strongly antiferromagnetically coupled (and hence EPR-silent at X band).…”

Section: Spectroscopic Studiesmentioning

confidence: 99%

“…Dimeric copper sites play an important role in the activation of biological oxygen [2][3][4], and the study of structural and functional aspects of copper metalloenzymes via model systems is a subject of intense research [5][6][7][8][9][10]. A member of the family of dicopper proteins is catechol oxidase, which features a type 3 copper center with two proximate copper ions coordinated primarily by histidine donors [11][12][13]. This enzyme catalyzes the two-electron oxidation of o-diphenols to the corresponding quinones.…”

Section: Introductionmentioning

confidence: 99%

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Structural and spectroscopic studies of a model for catechol oxidase

et al. 2008

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A binuclear copper complex, [Cu 2 (BPMP) (OAc) 2 ][ClO 4 ]ÁH 2 O, has been prepared using the binucleating ligand 2,6-bis[bis(pyridin-2-ylmethylamino)methyl]-4-methylphenol (H-BPMP). The X-ray crystal structure reveals the copper centers to have a five-coordinate square pyramidal geometry, with the acetate ligands bound terminally. The bridging phenolate occupies the apical position of the square-based pyramids and magnetic susceptibility, electron paramagnetic resonance (EPR) and variable-temperature variable-field magnetic circular dichroism (MCD) measurements indicate that the two centers are very weakly antiferromagnetically coupled (J = -0.6 cm -1 ). Simulation of the dipole-dipole-coupled EPR spectrum showed that in solution the Cu-O-Cu angle was increased from 126°to 160°and that the internuclear distance was larger than that observed crystallographically. The high-resolution spectroscopic information obtained has been correlated with a detailed ligand-field analysis to gain insight into the electronic structure of the complex. Symmetry arguments have been used to demonstrate that the sign of the MCD is characteristic of the tetragonally elongated environment. The complex also displays catecholase activity (k cat = 15 ± 1.5 min -1 , K M = 6.4 ± 1.8 mM), which is compared with other dicopper catechol oxidase models.

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Section: Spectroscopic Studiesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Structural and spectroscopic studies of a model for catechol oxidase

et al. 2008

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“…Although the type 3 proteins fulfill different functions, the dinuclear active site seems to be highly conserved as witnessed by its characteristic spectroscopic signatures and the available crystal structures for several Hcs (9 -11) and a catechol oxidase (12). The differences in functionality are therefore thought to derive from variations in the accessibility of substrates to the active site or the ability of substrates to appropriately dock into the active center (7,13,14).…”

mentioning

confidence: 99%

Stopped-flow Fluorescence Studies of Inhibitor Binding to Tyrosinase from Streptomyces antibioticus

Tepper

Bubacco

Canters

2004

Journal of Biological Chemistry

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“…Based on the pK a values, the active species for 1 and 2 can be assigned to the aquahydroxo complex. 14,[62][63][64] The substrate dependence was carried out at pH 9, and a Michaelis-Menten profile was obtained (Figure 10 for complex 1, and Figure S3 for complex 2). The parameters obtained by a non-linear fit are presented in Table 3.…”

Section: Catechol Oxidationmentioning

confidence: 99%

Binuclear CuII complexes as catalysts for hydrocarbon and catechol oxidation reactions with hydrogen peroxide and molecular oxygen

Martins¹,

Souza²,

Fernandez³

et al. 2010

J. Braz. Chem. Soc.

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Dois ligantes tridentados, HL1, [(2-hidroxibenzil)(2-(imidazol-2-il)etil)]amina, e HL2, [(2-hidroxibenzil)(2-(piridil-2-il)etil]amina, foram usados na síntese dos complexos binucleares [Cu 2 (L1) 2 ]Cl 2• 2H 2 O, complexo 1, e [Cu 2 (L2) 2 ] (ClO 4 ) 2• 1.5H 2 O, complexo 2, para serem empregados como catalisadores em processos de oxidação. Os complexos foram caracterizados por análise elementar e espectroscopias na região do infravermelho, ultravioleta-visível e ressonância paramagnética eletrônica. Foram também estudados por voltametria cíclica e titulação potenciométrica, a fim de caracterizar seus comportamentos em solução. A resolução da estrutura cristalina do complexo 1 mostrou um cátion binuclear contendo dois grupos fenóxido em ponte. Este arranjo possui uma distância Cu … Cu de 3.043(10) Å, similar à observada na catecol oxidase (2.90 Å). Os comportamentos catalíticos destes complexos foram investigados nas oxidações de cicloexano e de catecol. Na oxidação de cicloexano observou-se baixa atividade para ambos os complexos, que pode ser atribuída ao estereoimpedimento produzido pela falta de coplanaridade entre os anéis aromáticos do arcabouço dos ligantes, sugerindo que a aproximação entre o substrato e o centro ativo binuclear é uma etapa determinante no mecanismo da reação. Com relação à atividade de catecolase, foram observadas altas eficiências, com o complexo 2 sendo mais ativo que o complexo 1. Isto indica que o ligante piridina é capaz de estabilizar melhor o intermediário proposto para esse processo, que contém o centro Cu • 1.5H 2 O, complex 2, in order to obtain catalysts for oxidative processes. Both complexes were characterized by elemental analysis, IR, UV-Vis and EPR spectroscopies. In addition, they were studied by cyclic voltammetry and potentiometric titration in order to investigate their behavior in solution. The crystal structure of complex 1 revealed a binuclear cation where the metal centers are bridged by two phenoxo groups. This arrangement provides a Cu … Cu distance of 3.043(10) Å, which is similar to the observed for catechol oxidase (2.90 Å). The catalytic reactivities of both complexes were investigated for hydrocarbon and catechol oxidations. Complexes 1 and 2 led to low overall hydrocarbon oxidation conversion values of 6.34 % and 7.15 %, respectively. However, for complex 1, only cyclohexanol (Cy-OH) and cyclohexanone (Cy=O) were isolated as reaction products, with selectivities of 68.1% for Cy-OH. This low overall conversion is tentatively attributed to steric hindrance effects produced by the non-coplanar aromatic rings of the ligand scaffolds, which suggest that the access of the hydrocarbon molecule to the binuclear active center is a determinant step in the reaction mechanism. Investigation of catecholase activities has shown high efficiencies, with complex 2 being more active than complex 1. It indicates that the pyridine-containing ligand is able to stabilize the intermediate Cu I Cu I center which is proposed to be formed in this process. This is corroborated by t...

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The Crystal Structure of Catechol Oxidase: New Insight into the Function of Type-3 Copper Proteins

Cited by 536 publications

References 39 publications

Structural and spectroscopic studies of a model for catechol oxidase

Structural and spectroscopic studies of a model for catechol oxidase

Stopped-flow Fluorescence Studies of Inhibitor Binding to Tyrosinase from Streptomyces antibioticus

Binuclear CuII complexes as catalysts for hydrocarbon and catechol oxidation reactions with hydrogen peroxide and molecular oxygen

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