1. Neutral p H and copper ions promote eumelanogenesis after the dopachrome stage.
- Author
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Ito, Shosuke, Suzuki, Natsumi, Takebayashi, Shiori, Commo, Stéphane, and Wakamatsu, Kazumasa
- Subjects
MELANINS ,PHYSIOLOGICAL effects of hydrogen-ion concentration ,COPPER ions ,PHENOL oxidase ,PIGMENTATION disorders ,BIODIVERSITY ,TYROSINE ,DOPACHROME tautomerase - Abstract
The diversity of pigmentation in the skin, hair, and eyes of humans has been largely attributed to the diversity of p H in melanosomes with acidic p H being proposed to suppress melanin production. Tyrosinase has an optimum p H of 7.4 and its activity is suppressed greatly at lower p H values. The first step of eumelanogenesis is the oxidation of tyrosine to dopachrome ( DC) via dopaquinone. However, how eumelanogenesis is controlled by p H beyond this stage is not known. In this study, we examined the effects of p H (5.3-7.3) on the conversion of DC to 5,6-dihydroxyindole ( DHI) and 5,6-dihydroxyindole-2-carboxylic acid ( DHICA) and the subsequent oxidation of DHI and DHICA to form eumelanin. The effects of Cu
2+ ions on those reactions were also compared. The results indicate that an acidic p H greatly suppresses the late stages of eumelanogenesis and that Cu2+ ions accelerate the conversion of DC to DHICA and its subsequent oxidation. [ABSTRACT FROM AUTHOR]- Published
- 2013
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