Sarna T, Sealy R C
Arch Biochem Biophys. 1984 Aug 1;232(2):574-8. doi: 10.1016/0003-9861(84)90575-7.
Formation of light-induced free radicals from natural eumelanin (from bovine eyes) and synthetic melanin (from oxidation of 3,4-dihydroxyphenylalanine) has been studied by electron spin resonance spectroscopy. Action spectra measured for natural melanins are very similar to that found for synthetic melanin, and are unaffected by the removal of associated protein. A comparison of action spectra with optical absorbance spectra shows that the former has a more marked wavelength dependence, suggesting that the chromophore that is most active in free-radical production is not the major melanin chromophore that absorbs visible light. Measurements of quantum yields for free-radical production have been made over a wavelength range from 600 to 230 nm. The efficiency of radical production from natural eumelanin is about three times greater than from the synthetic material. Although production of the melanin radicals detected is independent of oxygen, some correlation with oxygen consumption is evident; quantum yields for radical production are approximately three times those for oxygen consumption obtained under similar conditions. Possible reasons for this are discussed.
利用电子自旋共振光谱法研究了天然真黑素（来自牛眼）和合成黑素（由3,4-二羟基苯丙氨酸氧化而成）光诱导自由基的形成。天然黑素的作用光谱与合成黑素的作用光谱非常相似，并且不受相关蛋白质去除的影响。作用光谱与光吸收光谱的比较表明，前者具有更明显的波长依赖性，这表明在自由基产生中最活跃的发色团不是吸收可见光的主要黑素发色团。已在600至230nm的波长范围内测量了自由基产生的量子产率。天然真黑素产生自由基的效率约为合成材料的三倍。虽然检测到的黑素自由基的产生与氧气无关，但与氧气消耗存在一些明显的相关性；在相似条件下，自由基产生的量子产率约为氧气消耗量子产率的三倍。文中讨论了其可能的原因。
