Tyrosinase Kinetics: Failure of Acceleration in Oxidation of Ring‐Blocked Monohydric Phenol Substrate

Naish-Byfield, S; Riley, Patrick A.

doi:10.1111/j.1600-0749.1998.tb00716.x

Cited by 26 publications

(23 citation statements)

References 16 publications

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“…9,10) The melanocytes produce melanin by a process that involves the transformation of tyrosine into 3,4-dihydroxyphenylalanine (DOPA) by the enzyme tyrosinase and the subsequent transformation of DOPA into melanin. 5,11,12) Tyrosinase is the key enzyme in the pathway of melanogenesis. Tyrosinase plays a regulatory role in the production of melanin.…”

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confidence: 99%

Effect of Radix Ginseng and Radix Trichosanthis on the Melanogenesis

Kim

Yun

et al. 2003

Biological & Pharmaceutical Bulletin

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Skin diseases are a hyperpigmentation, hypopigmentation and melanoma, etc. Among them, recent studies have focused on the hyperpigmentation, which is especially abnormally increased colorations or spots. Hyperpigmentation such as chloasma, coloration or freckles increased abnormally the amount of melanin in the epidermis. [1][2][3][4][5] Some of the principle causes of hyperpigmentation are exposured to ultraviolet light, genetic reasons, metabolism, inflammation, infection, the endocrine system and reminded scars. [6][7][8] Melanin is synthesized in melanosomes of the melanocyte. The formed melanin granules are moved from the melanocytes cytoplasmic extensions to keratinocytes. 9,10) The melanocytes produce melanin by a process that involves the transformation of tyrosine into 3,4-dihydroxyphenylalanine (DOPA) by the enzyme tyrosinase and the subsequent transformation of DOPA into melanin. 5,11,12) Tyrosinase is the key enzyme in the pathway of melanogenesis. Tyrosinase plays a regulatory role in the production of melanin.13-15) Accordingly, the regulation of tyrosinase may not only control melanin production but also develop new therapy for pigmentation. Pharmaceutical agents which control melanin production or melanin metabolism are used as whitening agents. A number of whitening compounds have been screened for their effectiveness in reducing melanogenesis. 16)Radix Trichosanthis (RT) is the dry roots of Trichosanthis kirilowii MAXIM. (Cucurbitaceae) collected in the spring and fall. It is used in traditional Chinese medicine as an antiphlogistic, antifebrile, and cough remedy. It was also found to be effective as an abortifacient.17) It was found that the active principle of RT is a basic protein named trichosanthin.18) Recently, we have demonstrated that the water extracts of RT dose-dependently inhibit melanin synthesis and also abrogate cAMP-induced melanogenesis in B16 cells, but develops cytotoxicity.19) Thus, it would be important to abrogate the deleterious effects of RT using agents with a more physiological action.Radix Ginseng (RG) is the dry root of Panax ginseng C.A. MEY. (Araliaceae), a worldwide well-known traditional Chinese medicine with the popular name "ginseng". The wildgrowing or cultivated ginseng root is collected in the fall and used as a tonic.20) The major constituents of ginseng are the saponins, which include 30 kinds of ginsenoside. 21,22) Recently, it has been shown that panaxadiol fraction and its ginsenosides could induce the antioxidant enzymes, such as superoxide dismutase and catalase, which are important for maintaining cell viability.23) Also RG possess adaptogen-like effect to foreign deleterious infringement. 24) In view of the above reports, it can be considered that RG inhibits the cytotoxicity caused by RT.Therefore, the present study was conducted to investigate the effects of RG and RT on the melanogenesis in B16 melanoma cells. MATERIALS AND METHODS Sample and Preparation of ExtractRT and RG were standardized articles of the Korean pharmacopoeia (KP). The extracts...

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Effect of Radix Ginseng and Radix Trichosanthis on the Melanogenesis

Kim

Yun

et al. 2003

Biological & Pharmaceutical Bulletin

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“…The cells were detached from culture bottles using 0.025% trypsin and 0.5 mM ethylenediaminetetra acetic acid in phosphate-buffered saline (PBS). B16F0 melanoma cells were seeded into 6-well plates at a density of 1ϫ10 5 Amino acids, the building blocks of proteins, play significant roles in numerous physiological events in mammals. As the effects of amino acids on melanogenesis have yet to be demonstrated, the present study was conducted to identify whether amino acids, in particular alanine, glycine, isoleucine and leucine, influence melanogenesis in B16F0 dose of sample reagent was added to a well and incubated for another 72 h. After each incubation, cells were washed with cold PBS.…”

Section: Methodsmentioning

confidence: 99%

“…2,3) Melanin is synthesized in the melanosomes of melanoma cells, which produce melanin by a process that involves the transformation of tyrosine into 3,4-dihydroxyphenylalanine (L-DOPA) by the enzyme tyrosinase and the subsequent transformation of L-DOPA into melanin. 4,5) Tyrosinase is the key enzyme in the pathway of melanogenesis, and plays a regulatory role in the production of melanin. [6][7][8] Accordingly, the regulation of tyrosinase may not only control melanin production but also provide a strategy for hypopigmentation.…”

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Combination of Amino Acids Reduces Pigmentation in B16F0 Melanoma Cells

Ishikawa¹,

Kawase²,

Ishii³

2007

Biological & Pharmaceutical Bulletin

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“…It was reported that the presence of at least small amount of oxytyrosinase in the native enzyme is essential to produce sufficient amount of diphenol and establish the active monophenolase cycle [41]. The met-tyrosinase form lacks monophenolase activity since binding of monophenol to this form scavenges part of tyrosinase from the catalytic turnover as a dead-end complex in the steady state of monophenolase activity [41][42][43][44]. The change of the pH stability for oxy-tyrosinase in different mushroom PPOs may be related with differences in the environmental conditions during development of mushrooms and/or differences in maturity stage of mushrooms that may be Fig.…”

Section: Ph Stabilitymentioning

confidence: 99%

Partial purification and kinetic characterization of mushroom stem polyphenoloxidase and determination of its storage stability in different lyophilized forms

Şimşek¹,

Yemenicioğlu²

2007

Process Biochemistry

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Monophenolase (1011 AE 626 U/g AP) and diphenolase activities (5163 AE 3059 U/g AP) of PPO in acetone powders (APs) of different mushroom stems varied considerably. However, the limited variation of average dipenolase (L-DOPA) to monophenolase (L-tyrosine) activity ratio (5.4 AE 0.7) in crude extracts showed the homogeneity of PPO from different mushroom stems. The change in extraction material or partial purification method (ammonium sulfate or acetone precipitation) did not affect the temperature stability, temperature and pH dependency and K m of monophenolase activity considerably. However, some changes were observed in pH stability and substrate specificity of PPO in different parties of mushroom stems. The most important aspects of mushroom stem PPO are its lower diphenolase to monophenolase activity ratio than mushroom cap PPO, low temperature dependency of activity between 25 and 40 8C (E a = 30 kJ/mol), broad optimum pH between 6 and 8, but lack of activity pH 5, and ability to use phloridzin as substrate. The mushroom stem PPOs partially purified and lyophilized by using sucrose, dextran or alginate showed moderate to high stability at À18 8C for 6-6.5 months. Thus, the mushroom stems obtained as a waste material during mushroom processing may be used as a more homogenous source than whole mushrooms to obtain PPO used for different industrial, clinical or research purposes. #

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Tyrosinase Kinetics: Failure of Acceleration in Oxidation of Ring‐Blocked Monohydric Phenol Substrate

Cited by 26 publications

References 16 publications

Effect of Radix Ginseng and Radix Trichosanthis on the Melanogenesis

Effect of Radix Ginseng and Radix Trichosanthis on the Melanogenesis

Combination of Amino Acids Reduces Pigmentation in B16F0 Melanoma Cells

Partial purification and kinetic characterization of mushroom stem polyphenoloxidase and determination of its storage stability in different lyophilized forms

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