Tyrosinases (sometimes referred to as polyphenol oxidases, monophenol monoxygenases,
catechol oxidases, cre-solases, or catecholases) are well known for their role in producing melanin in vertebrates.
Catechol (CT), hydroquinone (HQ), and KCl were purchased from Sigma-Aldrich, and graphite (G) (>99%) was purchase from Fluka.
First, commercially available 3,4-dihydroxybenzaldehyde was converted to the corresponding
catechol aldehyde (2) by reacting it with compound 1.
Laccase from Trametes versicolor (EC 1.10.3.2), with an activity of 13.6 U/mg, was obtained from Sigma; sodium acetate trihydrate was from JT Baker; acetic acid glacial was from Laboratorios Lutz, Mexico, 60.05%; caffeic acid, gallic acid, and
catechol were from Fluka; ethanol was from Sigma-Aldrich (HPLC degree); Hg[(N[O.sub.3]).sub.2] was from Sigma-Aldrich; and deionized water was from a MilliQ Millipore equipment.
Catechol (Sigma-Aldrich, Germany) as substrate in concentrations of 0.0, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.10, 0.11 and 0.120M was prepared, and 3ml of each concentration was placed into a quartz cell along with 75[micro]l of each inhibitor or their combinations.
The researchers applied polyphenol coatings to the surface of chitosan-grafted polypropylene by using the laccase-assisted oxidative polymerization of
catechol and catechin.
For it, 0.5 mL phosphate buffer (0.1 M, PH7) was added to 200 uL enzyme solution and 200 uL
catechol solution (2%).
Alternatively, reactive oxygen species (ROS) generated from redox cycling of both stilbene and
catechol estrogens can act as signaling messengers also that are also involved in cell growth [7, 12, 13].
Multidentates [beta]-diketonates biscatecholamide ligands [6] have six binding sites due to the O-donor of
catechol aromatic ring and [beta]-diketonates [7, 8].