Pirie A
Biochem J. 1968 Sep;109(2):301-5. doi: 10.1042/bj1090301.
Oxidation of tyrosine in the presence of bovine lens proteins leads to the formation of brown or black melanoproteins. Both tyrosinase and the oxidizing system of ferrous sulphate-ascorbic acid-EDTA are effective. The fluorescence of the lens proteins is both altered and enhanced by the tyrosine-oxidizing systems. Their fluorescence spectra resemble those of urea-insoluble proteins of human cataractous lens and of 1,2-naphthaquinone-proteins of naphthalene cataract. The lens proteins lose their thiol groups and, in acid hydrolysates of treated beta-and gamma-crystallins, a substance has been detected chromatographically that behaves similarly to a compound formed when 3,4-dihydroxyphenylalanine (dopa) is oxidized by tyrosinase in the presence of cysteine. Analysis and behaviour of this substance from hydrolysates of lens proteins suggest that it is a compound of cysteine and dopa.
在牛晶状体蛋白存在的情况下,酪氨酸氧化会导致棕色或黑色黑素蛋白的形成。酪氨酸酶以及硫酸亚铁 - 抗坏血酸 - 乙二胺四乙酸氧化系统均有效。酪氨酸氧化系统会改变并增强晶状体蛋白的荧光。它们的荧光光谱类似于人类白内障晶状体的尿素不溶性蛋白以及萘白内障的1,2 - 萘醌蛋白的荧光光谱。晶状体蛋白失去其巯基,并且在经处理的β - 和γ - 晶状体蛋白的酸水解物中,通过色谱法检测到一种物质,其行为类似于3,4 - 二羟基苯丙氨酸(多巴)在半胱氨酸存在下被酪氨酸酶氧化时形成的化合物。来自晶状体蛋白水解物的这种物质的分析和行为表明它是半胱氨酸和多巴的化合物。