The tellurium oxyanion tellurate is toxic to living organisms even at low concentrations; however, its mechanism of toxicity is poorly understood. Here, we show that exposure of Escherichia coli K-12 to tellurate results in reduction to elemental tellurium (Te[0]) and the formation of intracellular reactive oxygen species (ROS). Toxicity assays performed with E. coli indicated that pre-oxidation of the intracellular thiol pools increases cellular resistance to tellurate—suggesting that intracellular thiols are important in tellurate toxicity. X-ray absorption spectroscopy experiments demonstrated that cysteine reduces tellurate to elemental tellurium. This redox reaction was found to generate superoxide anions. These results indicate that tellurate reduction to Te(0) by cysteine is a source of ROS in the cytoplasm of tellurate-exposed cells.

碲氧阴离子碲酸盐即使在低浓度下也对生物体有毒；然而，人们对其毒性机制知之甚少。在这里，我们表明大肠杆菌K-12 暴露于碲酸盐会导致元素碲 (Te[0]) 的减少和细胞内活性氧 (ROS) 的形成。用大肠杆菌进行的毒性测定表明细胞内硫醇池的预氧化增加了细胞对碲酸盐的抗性 - 这表明细胞内硫醇在碲酸盐毒性中很重要。X 射线吸收光谱实验表明，半胱氨酸将碲酸盐还原为元素碲。发现这种氧化还原反应会产生超氧阴离子。这些结果表明，半胱氨酸将碲酸盐还原为 Te(0) 是碲酸盐暴露细胞的细胞质中 ROS 的来源。