Felix K, Lengfelder E, Hartmann H J, Weser U
Strahlenbiologisches Institut, Ludwig-Maximilians-Universität München, Germany.
Biochim Biophys Acta. 1993 Nov 10;1203(1):104-8. doi: 10.1016/0167-4838(93)90042-p.
In a pulse radiolytic study employing aqueous intact yeast copper(I)-thionein at pH 7 it was shown that both superoxide and hydroxyl radicals efficiently react with this Cu(I)- and thiolate-rich protein. The reaction constant of hydroxyl radicals with Cu(I)-thionein was determined by competition kinetics and was 2.2 x 10(11) M-1 s-1 at a rate close to a diffusion-controlled limit. The reaction of Cu(I)-thionein with superoxide was also successful and proceeded at a rate of 7.5 x 10(6) M-1 s-1. According to chiroptical and luminescence emission measurements minor oxidation of the copper(I)-thiolate oligonuclear binding centres was observed, leading to the release of some Cu(II). It is important to realise the dual reactivity of this yeast Cu(I)-thiolate protein in controlling copper transport and storage as well as its distinct role in the scavenging of free radicals.
在一项脉冲辐解研究中，使用pH值为7的完整酵母铜（I）-硫蛋白水溶液，结果表明超氧自由基和羟基自由基都能与这种富含铜（I）和硫醇盐的蛋白质有效反应。通过竞争动力学测定了羟基自由基与铜（I）-硫蛋白的反应常数，在接近扩散控制极限的速率下，该常数为2.2×10¹¹ M⁻¹ s⁻¹。铜（I）-硫蛋白与超氧自由基的反应也很成功，反应速率为7.5×10⁶ M⁻¹ s⁻¹。根据圆二色光谱和发光发射测量结果，观察到铜（I）-硫醇盐寡核结合中心发生了轻微氧化，导致一些铜（II）释放。认识到这种酵母铜（I）-硫醇盐蛋白在控制铜运输和储存方面的双重反应性及其在清除自由基方面的独特作用非常重要。
