Premium
Neutral p H and copper ions promote eumelanogenesis after the dopachrome stage
Author(s) -
Ito Shosuke,
Suzuki Natsumi,
Takebayashi Shiori,
Commo Stéphane,
Wakamatsu Kazumasa
Publication year - 2013
Publication title -
pigment cell and melanoma research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.618
H-Index - 105
eISSN - 1755-148X
pISSN - 1755-1471
DOI - 10.1111/pcmr.12137
Subject(s) - melanosome , chemistry , tyrosinase , melanin , tyrosine , copper , ion , photochemistry , biochemistry , biophysics , nuclear chemistry , enzyme , organic chemistry , biology
Summary 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 Cu 2+ ions accelerate the conversion of DC to DHICA and its subsequent oxidation.