Tyrosinase: a comprehensive review of its mechanism

Sánchez‐Ferrer, Álvaro; Rodrı́guez-López, José Neptuno; Garcı́a-Cánovas, Francisco; García-Carmona, Francisco

doi:10.1016/0167-4838(94)00204-t

Cited by 1,120 publications

(803 citation statements)

References 79 publications

Supporting

Mentioning

761

Contrasting

Unclassified

Order By: Relevance

“…23 The inspection of the spectra for those complexes containing the nitrate anion, measured in the 1800 -1200 cm -1 region, allowed us to verify the coordination modes of this anion. Lever and Montovani studied the IR absorptions of the NO 3 -group in this region for diverse coordination modes. 24 The analyzed complexes showed a complicated spectrum in this region, which was consistent with the presence of both ionic and coordinated NO 3 -groups, confirmed by X-ray diffraction.…”

Section: Ir Spectroscopymentioning

confidence: 99%

“…1 Additionally some of them were used to construct exotic molecular architectures, sensitize photoelectrochemical cells, label biomaterials as the basis for selective sensors, and also to obtain new magnetic materials. 2 Copper-containing active sites are responsible, in vivo, for the catalyzed oxidation of phenols, and amines, where two-electron transfer occurs between the substrate and two metal centres, as in tyrosinase and catechol oxidases, 3 or Equilibria and Catalytic Properties of a Chloro-Bridged Diimine Copper(II) Complex Vol. 15, No.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Equilibria and catalytic properties of a chloro-bridged Diimine copper(II) complex in the N,N,N',N'-tetramethyl-p-phenylenediamine (TMPD) oxidation

Alves¹,

Almeida-Filho²,

Santos³

et al. 2004

J. Braz. Chem. Soc.

View full text Add to dashboard Cite

2 Cl 2 ]X 2 ·nH 2 O preparada como sais perclorato 3, nitrato 4 e cloreto 5, respectivamente, foram isoladas e caracterizadas por técnicas espectroscópicas (UV/Vis, IV e EPR). O composto 2 teve sua estrutura determinada por cristalografia de raios-X. Em solventes não-aquosos predomina a espécie dinuclear, enquanto em solução aquosa, ou solventes contendo água, um equilíbrio entre a espécie dinuclear e a mononuclear 1 foi observado. Estudos cinéticos, em metanol, da oxidação catalisada de TMPD indicaram uma dependência de primeira-ordem da velocidade inicial com a concentração de catalisador e um efeito de saturação com aumento da concentração de substrato. O composto dinuclear é mais reativo que o mono-, e experimentos adicionais mostraram que o contra-íon cloreto afeta significativamente os parâmetros cinéticos, deslocando o equilíbrio envolvendo as espécies 2 e 5, além de estabilizar um par iônico com o substrato.Some new copper(II) complexes with a tridentate imine ligand, bimpy (or 2-(benzimidazolyl)methylene-2-amino-1-ethylpyridine), were prepared, and had their catalytic activity in the N,N,N´,N´-tetramethyl-p-phenylenediamine (TMPD) oxidation compared. Mononuclear species, [Cu(bimpy)(H 2 O) 2 ](NO 3 ) 2 , (1) and [Cu(bimpy)Cl 2 ]·H 2 O, (2), as well as the dinuclear species containing chloro-bridges, [Cu 2 (bimpy) 2 Cl 2 ]X 2 ·nH 2 O as perchlorate 3, nitrate 4 and chloride 5 salts, respectively, were obtained and characterized by different techniques (UV/Vis, IR, EPR and X-ray crystallography). In non-aqueous solvents, the dinuclear species predominates; however, in aqueous solution or solvents containing water, equilibrium between dinuclear and correlated mononuclear species 1 was verified. Kinetic studies, in methanol solution, on the catalyzed TMPD oxidation indicated a first-order dependence of the initial rate with the catalyst concentration, and a saturation effect with increasing concentrations of the substrate. The dinuclear species was observed to be more reactive than the mononuclear one, and further experiments showed that the counter-ion chloride can significantly affect the kinetic parameters, mostly by shifting the mono-/dinuclear equilibrium, and stabilizing an ion-pair with the substrate.Keywords: copper(II) complexes, dinuclear species, equilibria, kinetics, catalytic activity IntroductionCopper complexes containing diimines have been extensively studied, and reported as good models for a variety of enzymes associated to the molecular oxygen metabolism. 1 Additionally some of them were used to construct exotic molecular architectures, sensitize photoelectrochemical cells, label biomaterials as the basis for selective sensors, and also to obtain new magnetic materials. 2 Copper-containing active sites are responsible, in vivo, for the catalyzed oxidation of phenols, and amines, where two-electron transfer occurs between the substrate and two metal centres, as in tyrosinase and catechol oxidases, 3 or 873 Equilibria and Catalytic Properties of a Chloro-Bridged Diimine Copper(II) Complex V...

show abstract

Section: Ir Spectroscopymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Equilibria and catalytic properties of a chloro-bridged Diimine copper(II) complex in the N,N,N',N'-tetramethyl-p-phenylenediamine (TMPD) oxidation

Alves¹,

Almeida-Filho²,

Santos³

et al. 2004

J. Braz. Chem. Soc.

View full text Add to dashboard Cite

show abstract

“…Due to their capabilities, like molecular oxygen transport (hemocyanin) or oxidation (tyrosinase), they have been subject to many theoretical [1][2][3][4][5][6][7][8] and experimental [9][10] investigations. Theoretically, their complicated electronic structures are particularly interesting due to the possibility of an antiferromagnetic coupling related to the open-shell singlet nature of the central metallic core.…”

Section: Introductionmentioning

confidence: 99%

Comments on the nature of the bonding in oxygenated dinuclear copper enzyme models

Piquemal

Pilmé

2006

Journal of Molecular Structure: THEOCHEM

View full text Add to dashboard Cite

show abstract

“…In the same work, experimental data showed that tyrosinase was inhibited by an excess of monophenol [5]. In a series of works [4,21], our group proposed the mechanism described in Scheme l, whereby tyrosinase is not inhibited by monophenol [21,22]. However, the inhibition of mushroom tyrosinase by excess of substrate has been described, but note that the absorbance is measured at 475 nm during the first three minutes following the start of the reaction, regardless of the concentration of substrate.…”

Section: Action Of 6bhmentioning

confidence: 99%

Effect of tetrahydropteridines on the monophenolase and diphenolase activities of tyrosinase

Molina

Muñoz

Varón

et al. 2007

Journal of Enzyme Inhibition and Medicinal Chemistry

View full text Add to dashboard Cite

This study explains the action of compounds such as 6-tetrahydrobiopterin, (6BH 4 ) and 6,7-dimethyltetrahydrobiopterin (6,7-di-CH 3 BH 4 ) on the monophenolase and diphenolase activities of tyrosinase. These reductants basically act by reducing the o-quinones, the reaction products, to o-diphenol. In the case of the diphenolase activity a lag period is observed until the reductant is depleted; then the system reaches the steady-state. In the action of the enzyme on monophenol substrates, when the reductant concentration is less than that of the o-diphenol necessary for the steady-state to be reached, the system undergoes an apparent activation since, in this way, the necessary concentration of o-diphenol will be reached more rapidly. However, when the reductant concentration is greater than that of the o-diphenol necessary for the steady-state to be reached, the lag period lengthens and is followed by a burst, by means of which the excess o-diphenol is consumed, the steady-state thus taking longer to be reached. Moreover, in the present kinetic study, we show that tyrosinase is not inhibited by an excess of monophenol, although, to confirm this, the system must be allowed to pass from the transition state and enter the steady-state, which is attained when a given amount of o-diphenol has accumulated in the medium.

show abstract

Tyrosinase: a comprehensive review of its mechanism

Cited by 1,120 publications

References 79 publications

Equilibria and catalytic properties of a chloro-bridged Diimine copper(II) complex in the N,N,N',N'-tetramethyl-p-phenylenediamine (TMPD) oxidation

Equilibria and catalytic properties of a chloro-bridged Diimine copper(II) complex in the N,N,N',N'-tetramethyl-p-phenylenediamine (TMPD) oxidation

Comments on the nature of the bonding in oxygenated dinuclear copper enzyme models

Effect of tetrahydropteridines on the monophenolase and diphenolase activities of tyrosinase

Contact Info

Product

Resources

About