Sodium salts of four n-alkyl xanthate compounds, C2H5OCS2Na (I), C3H7OCS2Na (II), C4H9OCS2Na (III), and C6H13OCS2Na (IV) were synthesized and examined for inhibition of both cresolase and catecholase activities of mushroom tyrosinase (MT) in 10 mM sodium phosphate buffer, pH 6.8, at 293 K using UV spectrophotometry. 4-[(4-Methylbenzo)azo]-1,2-benzendiol (MeBACat) and 4-[(4-methylphenyl)azo]-phe...

Background: Tyrosinase is a copper-containing enzyme, which is widely distributed in microorganisms, animals and plants. It is also a key enzyme in melanin biosynthesis, which plays a crucial role in determining the color of mammalian skin and hair. In addition, unfavorable enzymatic browning of plant-derived foods by tyrosinase causes a decrease in nutritional quality and economic loss of food...

Phenoloxidase activity in crayfish haemocyte lysates and extracts of haemocyte membranes were studied using native PAGE and SDS-PAGE gels and staining for cresolase, catecholase and laccase activities. The activation of the proenzyme, prophenoloxidase to phenoloxidase, in native PAGE was demonstrated following exposure to SDS. By staining samples separated in SDS-PAGE followed by renaturation, ...

Polyphenol oxidase from Black mulberrys was extracted and partially purified through (NH4)2SO4 precipitation, dialysis and ion exchange chromatography. P-cresol was the better substrate for cresolase activity with a Km (11.5 mM) and catechol for catecholase activity with Km (6.4 mM) at pH 5. Km for cresolase and catecholase activity of IsoPPOII at pH 6.5 were 12 and 8.5 and for IsoPPOIII at pH ...

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...

background tyrosinase is a copper-containing enzyme, which is widely distributed in microorganisms, animals and plants. it is also a key enzyme in melanin biosynthesis, which plays a crucial role in determining the color of mammalian skin and hair. in addition, unfavorable enzymatic browning of plant-derived foods by tyrosinase causes a decrease in nutritional quality and economic loss of food ...

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...

Polyphenol oxidase (PPO) (monophenol, o-diphenol: oxygen oxidoreductase; EC 1.14.18.1) is a binuclear copper-cluster-containing monooxygenase ubiquitously present in biological systems (1, 2). PPO may be distinguished from the related oxidase laccase [p-diphenol:oxygen oxidoreductase; EC 1.10.3.2] by its substrate specificity and the type and number of catalytic coppers. PPO catalyzes the oxida...