Study of stereospecificity in mushroom tyrosinase

Espı́n, Juan Carlos; Garcı́a-Ruiz, Pedro Antonio; Tudela, José; Garcı́a-Cánovas, Francisco

doi:10.1042/bj3310547

Cited by 100 publications

(90 citation statements)

References 31 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…The K m and k cat values derived from steady-state kinetic measurements are indistinguishable for L-and D-DOPA, suggesting that Cu-S100B does not exert stereochemical selectivity. Similar kinetic data for tyrosinase oxidation of L-and D-DOPA demonstrate more than a 2-fold increase in K m for the D-over the L-stereoisomer (Table 1), establishing the ability of this enzyme to discriminate between the optical isomers (38).…”

Section: Resultsmentioning

confidence: 56%

Catecholase Activity Associated with Copper-S100B

et al. 2003

View full text Add to dashboard Cite

This study addresses the spectroscopic properties and reactivity associated with the copperloaded form of S100B isolated from bovine brain. Copper(II)-S100B displays EPR features typical of a type II copper center and is shown here to exhibit catecholase activity, the two-electron oxidation of catechols. The steady-state kinetics associated with the oxidation of several catecholamines has been probed in order to further characterize this activity. The evidence provided indicates that the catecholase chemistry is copper initiated. Superoxide dismutase has no effect on the rates of catecholamine oxidation catalyzed by Cu-S100B, establishing that superoxide is not produced during this reaction, ruling out an autoxidative mechanism. Addition of catalase to the Cu-S100B reaction with catechols reduces the amount of oxygen consumed by 50%, demonstrating that peroxide is released during this reaction. The release of peroxide is mechanistically distinct from the type III dinuclear copper proteins, catechol oxidase and tyrosinase.

show abstract

Section: Resultsmentioning

confidence: 56%

Catecholase Activity Associated with Copper-S100B

et al. 2003

View full text Add to dashboard Cite

show abstract

“…Mycobacterium leprae can oxidize both L-and D-DOPA (Prabhakaran et al, 1972). Mushroom tyrosinase can oxidize both L-and D-DOPA, albeit with a higher K m for D-DOPA, a finding that presumably reflects chiral-side-chain effects on enzyme activity (Espin et al, 1998). Similarly, polyphenoloxidase activity from the avocado plant (Persea americana) has similar reaction kinetics for the oxidation of L-and Disomers of DOPA, and for L-and D-tyrosine (Kahn & Pomerantz, 1980).…”

Section: Discussionmentioning

confidence: 81%

Cryptococcus neoformans laccase catalyses melanin synthesis from both d- and l-DOPA

et al. 2007

View full text Add to dashboard Cite

The human fungal pathogen Cryptococcus neoformans produces melanin in the presence of various substrates, including the L enantiomer of 3,4-dihydroxyphenylalanine (DOPA). The enzyme laccase catalyses the formation of melanin by oxidizing L-DOPA, initiating a series of presumably spontaneous reactions that ultimately leads to the polymerization of the pigment in the yeast cell wall. There, melanin protects the cell from a multitude of environmental and host assaults. Thus, the ability of C. neoformans to produce pigments from a variety of available substrates is likely to confer a survival advantage. A number of C. neoformans isolates of different serotypes produced pigments from D-DOPA, the stereoisomer of L-DOPA. Acid-resistant particles were isolated from pigmented C. neoformans cells grown in the presence of D-DOPA. Biophysical characterization showed the particles had a stably detectable free-radical signal by EPR, and negative zeta potential, similar to L-DOPA-derived particles. No major differences were found between L-and D-DOPA ghosts in terms of binding to anti-melanin antibodies, or in overall architecture when imaged by electron microscopy. C. neoformans cells utilized L-and D-DOPA at a similar rate. Overall, our results indicate that C. neoformans shows little stereoselectivity for utilizing DOPA in melanin synthesis. The ability of C. neoformans to use both L and D enantiomers for melanization implies that this organism has access to a greater potential pool of substrates for melanin synthesis, and this could potentially be exploited in the design of therapeutic inhibitors of laccase.

show abstract

“…Plant tyrosinase is different from mammalian tyrosinase because of its unique requirements for substrate and cofactor as well as its different sensitivity to inhibitors. 7,8) Several papers published in Chinese indicated that many plant extracts showing inhibitory activity to mushroom tyrosinase in vitro did not reduce pigmentation activity in cells. Also, some compounds tested on mammalian tyrosinase did not give comparable results with mushroom tyrosinase.…”

Section: -3)mentioning

confidence: 99%

Depigmentation of Melanocytes by the Treatment of Extracts from Traditional Chinese Herbs: a Cell Culture Assay

Zhong

Ahn

et al. 2006

Biological & Pharmaceutical Bulletin

View full text Add to dashboard Cite

Current therapies are still unsatisfied for skin pigmentation disease conditions. Furthermore, Asian women prefer lighter skin color and there is a great demand to develop more safe and effective skin whitening agents. Recently, many efforts have been paid to develop new therapeutic agents against pigmentation abnormalities, especially using novel biologically active compounds from natural plants. Many tyrosinase inhibitors that suppress melanogenesis have been actively studied with the aim of developing new whitening agents. 1-3)Medicinal plants are most suitable for pharmacological research and drug development, because their constituents can be used not only as therapeutic agents but also as starting materials or models for the synthesis of drugs or pharmacologically active compounds. We are interested in re-evaluation of traditional Chinese herbs on melanogenesis from huge resources of famous whitening formulations and recipes in ancient literature. Traditional Chinese medicine has been used for the treatment of chloasma for a long history. Many famous ancient formulations and recipes are still in use to treat pigmentation disorders. Though these drugs were reported to be clinically effective in China, the mechanism and the active components have not been studied yet. Evaluation of Chinese herbal medicine in the treatment of skin pigmentation abnormalities may be beneficial for the development of new and more efficient remedies. In China, search for depigmentation medicine from traditional Chinese herbs is currently focused on those having inhibitory activity to tyrosinase. In a previous screening study performed by Japanese researchers with mushroom tyrosinase, several extracts of crude traditional Chinese drugs showed highly inhibitory activity. 4) Results from these studies provided important information about traditional Chinese herbs on melanogenesis. However, melanin biosyntheis is a complicated process involving many factors including the key enzymes tyrosinase, tyrosinase related protein-1 (TRP-1), tyrosinase related protein-2 (TRP-2), cytokines from autocrine and paracrine and those related to melanin transportation and decomposition. 5,6) Mushroom tyrosinase test is a simple method but with some disadvantages. Plant tyrosinase is different from mammalian tyrosinase because of its unique requirements for substrate and cofactor as well as its different sensitivity to inhibitors. 7,8) Several papers published in Chinese indicated that many plant extracts showing inhibitory activity to mushroom tyrosinase in vitro did not reduce pigmentation activity in cells. Also, some compounds tested on mammalian tyrosinase did not give comparable results with mushroom tyrosinase.9) Thus, this study was undertaken to evaluate the depigmentation effect of traditional Chinese herbs based on melanocyte cell culture assays. MATERIALS AND METHODS Preparation of Herb ExtractsIdentification of the herbs used in this study was provided by the Union Bioengineering Institute (Beijing, China). The raw herbs were extracted wit...

show abstract

Study of stereospecificity in mushroom tyrosinase

Cited by 100 publications

References 31 publications

Catecholase Activity Associated with Copper-S100B

Catecholase Activity Associated with Copper-S100B

Cryptococcus neoformans laccase catalyses melanin synthesis from both d- and l-DOPA

Depigmentation of Melanocytes by the Treatment of Extracts from Traditional Chinese Herbs: a Cell Culture Assay

Contact Info

Product

Resources

About