Electron transfer and photoprotective properties of melanins in solution.
Electron transfer and photoprotective properties of melanins in solution.
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DOI：
10.1111/j.1600-0749.1997.tb00487.x
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发表时间：
1997-08
期刊：
影响因子：
--
通讯作者：
J. Menter;I. Willis
中科院分区：
文献类型：
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作者：
J. Menter;I. Willis
真黑素的多醌性质使它们能够将电子供体的氧化与电子受体的还原偶联。我们研究了合成（西格玛）和“生物”（乌贼乌贼）黑色素介导羟基苯供体（酪氨酸，多巴，化学脱色剂）和模型受体（铁氰化物，酪氨酸酶）之间的电子转移的能力。1)根据还原剂的不同，黑色素可以延缓或加速铁氰化物的还原。反应动力学是一致的机制，涉及非相互作用的结合的羟基苯和铁氰化物的黑色素之前，耦合电子转移。2)黑色素还充当电子导管，显著加速酪氨酸酶催化的对羟基苯甲醚（MMEH）的氧化。活性物质似乎是黑色素和MMEH之间的复合物。这两种效应的大小取决于黑色素的类型及其氧化状态。乌贼（欧盟）黑色素似乎保护免受紫外线诱导的损害酸溶性胶原蛋白，作为判断的内在胶原蛋白荧光的不可逆损失。针对这种类型的损伤的光保护似乎主要涉及颜料的光吸收/散射。
The polyquinoid nature of eumelanin(s) enables them to couple oxidation of electron donors with the reduction of electron acceptors. We have studied the ability of synthetic (Sigma) and "biological" (cuttlefish sepia) melanins to mediate electron transfer between hydroxybenzene donors (tyrosine, dopa, chemical depigmenters) and model acceptors (ferricyanide, tyrosinase). 1) Depending on the reductant, melanin either retards or accelerates ferricyanide reduction. Reaction kinetics are consistent with a mechanism involving non-interactive binding of both hydroxybenzene and ferricyanide to melanin prior to coupled electron transfer. 2) Melanins also act as an electron conduit in markedly accelerating the tyrosinase-catalyzed oxygenation of p-hydroxyanisole (MMEH). The active species appears to be a complex between melanin and MMEH. The magnitude of both effects depend on the type of melanin as well as its oxidation state. Sepia (eu)melanin appears to protect against UV-induced damage to acid-soluble collagen, as judged by irreversible loss of intrinsic collagen fluorescence. Photoprotection against this type of damage appears primarily to involve optical absorption/scattering by the pigment.