Chedekel M R, Murr B L, Zeise L
Facility for Advanced Instrumentation, University of California, Davis 95616.
Pigment Cell Res. 1992 Sep;5(3):143-7. doi: 10.1111/j.1600-0749.1992.tb00010.x.
Melanin isolated from the ink sac of cuttle fish (Sepia melanin) is a proposed standard for natural eumelanin. Sepia melanin isolated by a standard protocol was submitted for both elemental analysis and quantitative amino acid analysis. The contribution of the detected amino acids to the elemental composition is subtracted from the total elemental analysis, and the resultant elemental composition reflects the composition of the Sepia melanin backbone chromophore. The assumption is made that, for eumelanins, there is only one nitrogen atom per monomeric unit, and thus, the empirical formula for the average monomeric Sepia melanin backbone chromophore was determined. Three key parameters can be determined for any melanin sample; namely, the molar C/N for the average monomeric unit, the formula weight of the average monomeric unit, and the total percent composition of amino acid residues. Three commonly used melanin preparations, namely, natural Sepia melanin, melanin prepared by the in vitro tyrosinase catalyzed polymerization of tyrosine (tyrosine-enzymatic melanin), and a polymer synthesized by the peroxide oxidative polymerization of tyrosine (tyrosine-chemical melanin), have been subjected to this standard method of characterization. Tyrosine-enzymatic and Sepia melanin are quite similar and tyrosine-chemical melanin is fundamentally different from the other two melanins.
从乌贼墨囊中分离出的黑色素（乌贼黑色素）被提议作为天然真黑素的标准。按照标准方案分离出的乌贼黑色素被送去进行元素分析和定量氨基酸分析。从总元素分析中减去检测到的氨基酸对元素组成的贡献，所得的元素组成反映了乌贼黑色素主链发色团的组成。假定对于真黑素，每个单体单元只有一个氮原子，因此确定了乌贼黑色素平均单体主链发色团的经验式。对于任何黑色素样品都可以确定三个关键参数；即平均单体单元的摩尔碳/氮比、平均单体单元的分子量以及氨基酸残基的总百分比组成。三种常用的黑色素制剂，即天然乌贼黑色素、通过酪氨酸的体外酪氨酸酶催化聚合制备的黑色素（酪氨酸酶促黑色素）以及通过酪氨酸的过氧化物氧化聚合合成的聚合物（酪氨酸化学黑色素），都采用了这种标准的表征方法。酪氨酸酶促黑色素和乌贼黑色素非常相似，而酪氨酸化学黑色素与其他两种黑色素有根本区别。
