Sarna T, Mailer C, Hyde J S, Swartz H M, Hoffman B M
Biophys J. 1976 Oct;16(10):1165-70. doi: 10.1016/S0006-3495(76)85765-7.
Electron-nuclear double resonance (ENDOR) signals from matrix protons interacting with the stable free radicals of "A"- and "B"-type melanins have been observed as a function of pH. In all samples the single line is similar in width and unusually narrow. The ENDOR reduction varies by more than a factor of 10, indicating a large sensitivity of relaxation properties of melanin to sample type. Signals were observed over a wide range of experimental conditions with good signal-to-noise ratio, establishing feasibility for further more detailed ENDOR studies. Incubation in D2O resulted in little change, indicating that the free radical is well buried or protected. No resolved hyperfine structure was seen, consistent with the generally accepted view that melanin is a heterogeneous polymer.
已经观察到与“A”型和“B”型黑色素的稳定自由基相互作用的基质质子的电子-核双共振（ENDOR）信号随pH的变化情况。在所有样品中，单线的宽度相似且异常狭窄。ENDOR信号强度的降低变化超过10倍，表明黑色素的弛豫特性对样品类型具有很大的敏感性。在广泛的实验条件下都观察到了信号，且信噪比良好，这为进一步进行更详细的ENDOR研究奠定了可行性。在D2O中孵育几乎没有变化，这表明自由基被很好地埋藏或保护。未观察到分辨出的超精细结构，这与黑色素是一种非均质聚合物这一普遍接受的观点一致。
