Tyrosinase, the enzyme that controls the synthesis of melanin, is a unique product of melanocytes. Normal and malignant human melanocytes grown in culture were used to study the factors that regulate the expression of tyrosinase. Immunoprecipitation experiments showed that newly synthesized tyrosinase appeared as a protein with an apparent molecular weight of 70,000 that was processed to a prot...

Pigmentation of the skin, hair and eyes is regulated by tyrosinase, the critical rate-limiting enzyme in melanin synthesis by melanocytes. Tyrosinase is degraded endogenously, at least in part, by the ubiquitin proteasome system (UPS). Several types of inherited hypopigmentary diseases, such as oculocutaneous albinism and Hermansky-Pudlak syndrome, involve the aberrant processing and/or traffic...

Tyrosinase was found to catalyze the oxidation of phenylhydrazine to phenol in a reaction that did not resemble those typically performed by tyrosinase. The kinetics of this reaction was investigated by measuring the initial velocity of the formation of phenol (25 °C). The values of k cat and K M for the oxidation of phenylhydrazine were obtained as 11.0 s(-1) and 0.30 mM, respectively. The gen...

Dopamine is one of the important medications of Portulaca oleracea L. To optimize the production of dopamine, one of the methods is the identification and engineering of metabolite pathways. To investigate the tyrosine decarboxylase (TDC) and tyrosinase, which seem to be the most important genes in dopamine synthesis pathway, hairy roots were produced from Portulaca oleracea using Agrobacterium...

melanin pigment plays a critical role in camouflage and   protection against harmful effects of solar radiation. melanogenesis is under   complex regulatory control by multiple agents. tyrosinase is a   multifunctional, which catalyzes the first two steps in mammalian   melanogenesis. in this study, inhibitory effects of astragalus fasciculifolius   and astragalus gypsicolus on diphenolase acti...

In mammalian melanocytes, melanosome is a highly specialized organelle where melanin is synthesized. Melanin synthesis is controlled by tyrosinase, the vital enzyme in melanogenic pathway. The present investigation is based on an effect of purified mushroom tyrosinase of Agaricus bisporus on B16F10 melanocytes for the melanin production via blocking pigment cell machinery. Using B16F10 melanocy...

The melanosome is a highly specialized organelle where melanin is synthesized. Tyrosinase and tyrosinase-related protein-1 (Tyrp1) are major melanosomal membrane proteins and key enzymes for melanin synthesis in melanocytes. Inulavosin, a melanogenesis inhibitor isolated from Inula nervosa (Compositae), reduced the melanin content without affecting either the enzymatic activities or the transcr...

In the presence of tyrosinase, red blood cells are Ipsed. Lysis follows an enzyme-mediated reaction, with the amount of lysis being proportional to the tyrosinase concentration. Cyanide, which inhibits tyrosinase, prevents lysis of the red blood cells by tyrosinase. Heat-denatured tyrosinase has no effect on red blood cells. Tyrosinase also exhibits a pronounced effect on the permeability of is...

The effects of lucidone on tyrosinase and antimelanogenic activity were investigated. Initially, we found that lucidone strongly inhibits the activity of mushroom tyrosinase. The effects of lucidone on tyrosinase were further examined in alpha-MSH-induced B16 melanoma cells. Lucidone significantly inhibits tyrosinase activity and leads to decreased melanin content in cultured B16 melanoma cells...

Tyrosinase inhibition studies are needed due to the medicinal applications such as hyperpigmentation. For probing effective inhibitors of tyrosinase, a combination of computational prediction and enzymatic assay via kinetics was important. We predicted the 3D structure of tyrosinase, used a docking algorithm to simulate binding between tyrosinase and phthalic acid (PA), and studied the reversib...