Rodríguez-Roldán Vicente, García-Heredia José Manuel, Navarro José A, De la Rosa Miguel A, Hervás Manuel
Instituto de Bioquímica Vegetal y Fotosíntesis, Centro de Investigaciones Científicas Isla de la Cartuja, Universidad de Sevilla and Consejo Superior de Investigaciones Científicas, Spain.
Biochemistry. 2008 Nov 25;47(47):12371-9. doi: 10.1021/bi800910v.
The effect of tyrosine nitration on the physicochemical properties and reactivity of human respiratory cytochrome c has been extensively analyzed. A set of mutants, each bearing only one tyrosine out of the five present in the wild-type molecule, has been constructed in order to study the effect of each tyrosine nitration on the properties of the whole protein. Replacement of tyrosines by phenylalanines does not promote significant changes in the properties of the cytochrome. Nitration of wild-type cytochrome c promotes a drastic decrease (ca. 350 mV) in the midpoint redox potential, probably induced by nitration of both tyrosines 48 and 67. Nitration also promotes a significant decrease in the intrinsic reactivity of all the wild-type and mutant proteins. Nitration of mutant cytochromes and, in particular, of the wild-type protein significantly decreases their reactivity with cytochrome c oxidase, thereby suggesting that this alteration is due to an accumulative effect of different nitrations. The reactivity of mutants bearing tyrosine 67 and, to a lesser extent, tyrosine 74 is more affected by nitration, indicating that the change in reactivity of nitrated wild-type cytochrome c is mainly due to nitration of these tyrosine residues. Moreover, nitration of wild-type cytochrome c induces a significant loss in its ability to activate caspases because of the additive effect of nitration of several tyrosine groups, as inferred from the behavior of monotyrosine mutants.
酪氨酸硝化对人呼吸细胞色素c的物理化学性质和反应活性的影响已得到广泛分析。为了研究每个酪氨酸硝化对整个蛋白质性质的影响，构建了一组突变体，每个突变体仅在野生型分子中存在的五个酪氨酸中含有一个酪氨酸。用苯丙氨酸取代酪氨酸不会导致细胞色素性质发生显著变化。野生型细胞色素c的硝化会使中点氧化还原电位急剧下降（约350 mV），这可能是由酪氨酸48和67的硝化所诱导的。硝化还会导致所有野生型和突变型蛋白质的固有反应活性显著降低。突变型细胞色素尤其是野生型蛋白质的硝化会显著降低它们与细胞色素c氧化酶的反应活性，从而表明这种改变是由于不同硝化的累积效应所致。带有酪氨酸67以及程度稍轻带有酪氨酸74的突变体的反应活性受硝化的影响更大，这表明硝化的野生型细胞色素c反应活性的变化主要是由于这些酪氨酸残基的硝化。此外，野生型细胞色素c的硝化会导致其激活半胱天冬酶的能力显著丧失，这是由于几个酪氨酸基团硝化的累加效应，这是从单酪氨酸突变体的行为推断出来的。
