Pheomelanogenesis is Promoted at a Weakly Acidic pH.
Pheomelanogenesis is Promoted at a Weakly Acidic pH.
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弱酸性 pH 值可促进黑素生成。
DOI：
10.1111/pcmr.12587
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发表时间：
2017
期刊：
影响因子：
--
通讯作者：
S.
中科院分区：
文献类型：
--
作者：
Wakamatsu;K.;Nagao;A.;Watanabe;M.;Nakao;K.;and Ito;S.
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，特别是真黑素生成。我们以前表明，酸性pH值大大抑制了多巴色素阶段后的真黑素生成的后期阶段。在半胱氨酸存在下酪氨酸酶对酪氨酸的氧化形成半胱氨酰多巴异构体，其进一步氧化以经由苯并噻嗪中间体产生褐黑素。然而，这些步骤如何受pH控制尚未表征。因此，我们研究了在酸性pH值下是否化学促进了褐黑素的合成。我们发现，在酪氨酸酶存在下，从多巴或酪氨酸中产生的褐黑素在pH值为5.8-6.3时最大，而真黑素的产生在pH值为5.8时受到抑制。这表明混合黑素生成在弱酸性pH下化学转移到更多的褐黑素状态。
The diversity of pigmentation in the skin, hair, and eyes of humans has been largely attributed to the diversity of pH in melanosomes with an acidic pH being proposed to suppress melanin production, especially eumelanogenesis. We previously showed that an acidic pH greatly suppresses the late stage of eumelanogenesis after the dopachrome stage. The oxidation of tyrosine by tyrosinase in the presence of cysteine forms cysteinyldopa isomers, which are further oxidized to give rise to pheomelanin via benzothiazine intermediates. However, how those steps are controlled by pH has not been characterized. We therefore examined whether pheomelanin synthesis is chemically promoted at an acidic pH. We found that pheomelanin production either from dopa or tyrosine in the presence of cysteine by tyrosinase was greatest at pH values of 5.8–6.3, while eumelanin production was suppressed at pH 5.8. This suggests that mixed melanogenesis is chemically shifted to more pheomelanic states at a weakly acidic pH.