An amperometric biosensor based on the enzyme polyphenoloxidase (PPO), which makes the bioelectrocatalysis of phenolic compounds, was developed and optimized using cathecol as substrate. Polyethersulphone membranes were used for enzyme immobilization. Polyphenoloxidase oxidizes monophenols (cresolase activity) and diphenols (catecholase activity) into the corresponding o-quinones; the o-quinone...

Neste trabalho, reportamos a síntese, caracterização e atividade de catecolase do complexo binuclear de cobre [Cu2(H2bbppnol)(μ-OAc)(μ-ClO4)] ClO4·H2O·EtOAc contendo o ligante N,N’-2-hidroxibenzil-N,N’-2-piridilmetil-2-hidroxipropano-1,3-diamina (H3bbppnol). O complexo foi caracterizado através de espectroscopias no infravermelho e eletrônica, ressonância paramagnética eletrônica, medidas de su...

In this work, we report on the catalytic activity of a manganese complex [(Cl)2Mn(RCOOET)], where RCOOET is ethyl-5-methyl-1-(((6-methyl-3-nitropyridin-2-yl)amino)methyl)-1H-pyrazole-3-carboxylate, in oxidation phenol or catechol by atmospheric oxygen to form o-quinone. The [(Cl)2Mn(RCOOET)] catalyzes at rate 3.74 µmol L−1 min−1 tetrahydrofuran (THF), similar manner catecholase tyrosinase.

We have undertaken the purification of mushroom tyrosinase to obtain homogeneous enzyme for a study of its mechanism, which is unknown. Purified mushroom tyrosinases have already been reported (l-9). Some of these preparations were homogeneous, or almost homogeneous, by either electrophoresis or ultracentrifugation; one was homogeneous by both criteria (3, 9). However, there are discrepancies a...

background tyrosinase, as a copper-containing enzyme, is widely distributed in different levels of life span. it is also a key enzyme in melanin biosynthesis, which plays a crucial role in determining the color of mammalian skin and hair. objectives the current study aimed to determine the effect of a palladium complex on cresolase and catecholase reactions of mushroom tyrosinase (mt). material...

Conjugation of naturally occurring catecholic compounds with thiols is a versatile and facile entry to a broad range of bioinspired multifunctional compounds for diverse applications in biomedicine and materials science. We report herein the inhibition properties of the caffeic aciddihydrolipoic acid S-conjugate, 2-S-lipoylcaffeic acid (LC), on mushroom tyrosinase. Half maximum inhibitory conce...