College of Food Science and Technology, Guangdong Provincial Key Laboratory of Aquatic Product Processing and Safety, Guangdong Provincial Engineering Technology, Research Center of Marine Food, Key Laboratory of Advanced Processing of Aquatic Products of Guangdong Higher Education Institution, Cunjin College, Guangdong Ocean University, Zhanjiang, China.
Institute for Food and Drug Control, Zhanjiang, China.
J Basic Microbiol. 2021 Apr;61(4):339-350. doi: 10.1002/jobm.202100012. Epub 2021 Feb 11.
Environment and food contamination with cadmium (Cd) can cause serious toxicity, posing a severe threat to agricultural production and human health. However, how amino acids contribute to defenses against oxidative stress caused by Cd in cells is not fully understood. As a model eukaryote with a relatively clear genetic background, Saccharomyces cerevisiae has been commonly used in Cd toxicity research. To gain insight into Cd toxicity and cell defenses against it, 20 amino acids were screened for protective roles against Cd stress in S. cerevisiae. The results showed that threonine (Thr, T) had the strongest protective effect against Cd-induced mortality and membrane damage in the cells. Compared to the antioxidant vitamin C (VC), Thr exhibited a higher efficacy in restoring the superoxide dismutase (SOD) activity that was inhibited by Cd but not by H O in vivo. Thr exhibited evident DPPH (2,2-diphenyl-1-picrylhydrazyl) activity but weak ABTS (2,2'-azino-bis(3-ethylbenzothiazoline-6-9 sulfonic acid)) scavenging activity, giving it a weaker effect against Cd-induced lipid peroxidation and superoxide radical O , compared to VC. More importantly, compared to the chelating agent EDTA, Thr showed stronger chelation of Cd, giving it a stronger protective effect on SOD against Cd than VC in vitro. The results of the in vivo and in vitro experiments revealed that the role Thr plays in cell defenses against Cd may be attributed to its protection of the SOD enzyme, predominantly through the preferential chelation of Cd. Our results provide insights into the protective mechanisms of amino acid Thr that ameliorate Cd toxicity and suggest that a supplement of Thr might help to reduce Cd-induced oxidative damage.
环境和食物中的镉（Cd）污染会导致严重的毒性，对农业生产和人类健康构成严重威胁。然而，氨基酸如何帮助细胞抵御 Cd 引起的氧化应激尚不完全清楚。作为一种具有相对清晰遗传背景的模式真核生物，酿酒酵母已广泛应用于 Cd 毒性研究。为了深入了解 Cd 毒性和细胞的防御机制，我们筛选了 20 种氨基酸，以研究它们在酿酒酵母细胞中对 Cd 胁迫的保护作用。结果表明，苏氨酸（Thr，T）对 Cd 诱导的细胞死亡率和膜损伤具有最强的保护作用。与抗氧化维生素 C（VC）相比，Thr 在体内恢复 Cd 抑制但 H O 不抑制的超氧化物歧化酶（SOD）活性方面的效果更高。Thr 表现出明显的 DPPH（2,2-二苯基-1-苦肼基）活性，但 ABTS（2,2'-联氮-双(3-乙基苯并噻唑啉-6-磺酸)）清除活性较弱，与 VC 相比，对 Cd 诱导的脂质过氧化和超氧自由基 O 作用较弱。更重要的是，与螯合剂 EDTA 相比，Thr 对 Cd 的螯合作用更强，在体外对 SOD 具有比 VC 更强的保护作用。体内和体外实验结果表明，Thr 在细胞抵御 Cd 中的作用可能归因于其对 SOD 酶的保护，主要是通过优先螯合 Cd。我们的研究结果为 Thr 减轻 Cd 毒性的保护机制提供了新的见解，并表明补充 Thr 可能有助于减少 Cd 诱导的氧化损伤。
