作者:Stefania Nicolis、Matteo Zucchelli、Enrico Monzani、Luigi Casella
DOI:10.1002/chem.200801014
日期:2008.9.26
semiquinone radicals, giving rise to different patterns of reactions. The former type of reaction can be promoted by tyrosinase, the latter by peroxidases in the presence of H(2)O(2), which can be formed under oxidative stress conditions. Both enzymes were employed for the characterization of the thiol-catechol adducts formed by reaction of DA and cysteine or glutathione, and for the identification of specific
由多巴胺(DA)氧化产生反应性醌类(DAQ)涉及神经退行性病变,如帕金森氏病(A. Borta,GU Hoglinger,J. Neurochem。2007,100,587-595)。DA氧化为DAQ可以通过半醌基团在单个两电子过程中或在两个连续的单电子步骤中发生,从而引起不同的反应方式。前一种反应可以通过酪氨酸酶促进,后者可以通过过氧化酶在H(2)O(2)存在下进行,而H(2)O(2)可以在氧化应激条件下形成。两种酶均用于表征由DA与半胱氨酸或谷胱甘肽反应形成的巯基-邻苯二酚加合物,并用于鉴定由DAQ修饰的两个代表性靶蛋白中的特定氨基酸残基,人和马的心脏肌红蛋白。我们的结果表明,半胱氨酸-DA加合物由相同的醌中间体形成,而与DA氧化机理无关,而自由基机理的标志是胱氨酸二聚体的形成。醌类的反应性还控制DA促进蛋白质中组氨酸残基的衍生化。然而,为了修饰人肌红蛋白中的半胱氨酸残基,已经提出了一