Neutral pH and copper ions promote eumelanogenesis after the dopachrome stage
Neutral pH and copper ions promote eumelanogenesis after the dopachrome stage
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DOI：
10.1111/pcmr.12137
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发表时间：
2013-11-01
影响因子：
4.3
通讯作者：
Wakamatsu, Kazumasa
中科院分区：
文献类型：
--
作者：
Ito, Shosuke;Suzuki, Natsumi;Wakamatsu, Kazumasa
人类皮肤、毛发和眼睛中色素沉着的多样性主要归因于黑素体中pH的多样性，酸性pH被提出来抑制黑素产生。酪氨酸酶的最适pH为7.4，在较低的pH值下，其活性被大大抑制。真黑素生成的第一步是酪氨酸通过多巴醌氧化为多巴色素（DC）。然而，真黑素生成如何被pH控制超过这个阶段是未知的。在这项研究中，我们研究了pH（5.3-7.3）对DC转化为5，6-二羟基吲哚（DHI）和5，6-二羟基吲哚-2-羧酸（DHICA）以及随后DHI和DHICA氧化形成真黑素的影响。并比较了Cu ~（2+）对这些反应的影响。结果表明，酸性pH值大大抑制了真黑素生成的后期阶段，并且Cu 2+离子加速DC向DHICA的转化及其随后的氧化。
The diversity of pigmentation in the skin, hair, and eyes of humans has been largely attributed to the diversity of pH in melanosomes with acidic pH being proposed to suppress melanin production. Tyrosinase has an optimum pH of 7.4 and its activity is suppressed greatly at lower pH values. The first step of eumelanogenesis is the oxidation of tyrosine to dopachrome (DC) via dopaquinone. However, how eumelanogenesis is controlled by pH beyond this stage is not known. In this study, we examined the effects of pH (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 Cu2+ ions on those reactions were also compared. The results indicate that an acidic pH greatly suppresses the late stages of eumelanogenesis and that Cu2+ ions accelerate the conversion of DC to DHICA and its subsequent oxidation.