Chauffe L, Windle J J, Friedman M
Biophys J. 1975 Jun;15(6):565-72. doi: 10.1016/S0006-3495(75)85838-3.
The electron spin resonances (ESR) of several native and modified melanins have been determined. Melanins isolated from black wool and synthesized from 3,4-dihydroxyl-L-phenylalanine (L-DOPA) and tyrosine all show similar ESR signals. Modification of the isolated melanins by treatment with reducing agents causes some lightening in color and slight changes in the ESR spectra. Lithium and liquid ammonia (Birch) reduction applied to melanins from wool and L-DOPA gave very different results, as reflected by ESR spectra, but in both cases the changes were much greater than those produced by other treatments. In general, reductive treatments in nonaqueous media in the presence of metals increase the free radical content and line width, whereas treatment in aqueous media resulted in decreased free radical content. These observations are consistent with a melanin pigment which is an irregular polymer and has unpaired electrons localized on different but similar monomer units.
已测定了几种天然和改性黑色素的电子自旋共振（ESR）。从黑羊毛中分离出的黑色素以及由3,4 - 二羟基 - L - 苯丙氨酸（L - DOPA）和酪氨酸合成的黑色素均显示出相似的ESR信号。用还原剂处理分离出的黑色素会导致颜色变浅以及ESR光谱发生轻微变化。将锂和液氨（伯奇还原）应用于羊毛和L - DOPA中的黑色素产生了非常不同的结果，这由ESR光谱反映出来，但在两种情况下变化都比其他处理产生的变化大得多。一般来说，在金属存在下于非水介质中进行还原处理会增加自由基含量和谱线宽度，而在水介质中处理则导致自由基含量降低。这些观察结果与一种黑色素色素一致，该色素是一种不规则聚合物，且具有位于不同但相似单体单元上的未成对电子。
