Mimick Of Tyrosinase And Selective Ortho-Hydroxylation Of Phenol

Tyrosinase (Tyr) catalyzes ortho-hydroxylation of monophenols to catechols (phenolase activity) and oxidation of catechols into o-quinones (catecholase activity) with high efficiency and selectivity under mild conditions. Chemical and spectroscopic studies indicate that the enzyme belongs to a family of type 3 copper proteins containing a binuclear copper active site coordinated by six histidines which involves in a variety of biological functions. It is well known that mimic enzyme catalysis is a novel challenging field in bioorganic chemistry with rapid progress. In this paper, we present a review on the advances of the chemical models research, especially the mimic of tyrosinase models including their structures, functions, and catalytic mechanism.Although imidazole is a good nitrogen donor, it has only limited use in practical studies of model systems of mimicking tyrosinase so far. Many researchers often use pyridine, pyrazole, benzimidazole, imine and amine as nitrogen donors in complexes instead of imdizole. To the best of our knowledge, the tyrosinase model system that are derived from polyimidazole ligands and exhibit tyrosinase-like activity on ortho-hydroxylation of exogenous phenols in the presence of dioxygen under mild conditions have not been reported. Herein, based on previous work in our group, we further develop a new method of preparing ligands and complexes. Using 2-substituted phenols as materials, a series of reactions have been taken including phenol ethers coupling, bromomethylation, quaternization, and Hoffmann-type elimination to obtain the tyrosinase model ligands and complexes containing polyimidazoles.Moreover,the phenolase activity of tyrosinase model complexes containing...