Research Center for Analytical Instrumentation, Institute of Cyber-Systems and Control, State Key Lab of Industrial Control Technology, Zhejiang University, Hangzhou 310058, PR China.
Int J Biochem Cell Biol. 2011 Dec;43(12):1802-11. doi: 10.1016/j.biocel.2011.08.019. Epub 2011 Sep 3.
Reactive oxygen species (ROS) are involved in cell growth, differentiation, and death. Excessive amounts of ROS (e.g., O(2)(-), H(2)O(2), and HO) play a role in aging as well as in many human diseases. Superoxide dismutase (SOD) and glutathione peroxidase (GPx) are critical antioxidant enzymes in living organisms. SOD catalyzes the dismutation of O(2)(-) to H(2)O(2), and GPx catalyzes the reduction of H(2)O(2) and other harmful peroxides by glutathione (GSH). They not only function in catalytic processes but also protect each other, resulting in more efficient removal of ROS, protection of cells against injury, and maintenance of the normal metabolism of ROS. To imitate the synergism of SOD and GPx, a 65-mer peptide (65P), containing sequences that form the domains of the active center of SOD and the catalytic triad of GPx upon the incorporation of some metals, was designed on the basis of native enzyme structural models; 65P was expressed in the cysteine auxotrophic expression system to obtain Se-65P. Se-65P was converted into Se-CuZn-65P by incorporating Cu(2+) and Zn(2+). Se-CuZn-65P exhibited high SOD and GPx activities because it has a delicate dual-activity center. The synergism of the enzyme mimic was evaluated by using an in vitro model and a xanthine/xanthine oxidase/Fe(2+)-induced mitochondrial damage model system. We anticipate that the peptide enzyme mimic with synergism is promising for the treatment of human diseases and has potential applications in medicine as a potent antioxidant.
活性氧（ROS）参与细胞的生长、分化和死亡。过量的 ROS（如 O(2)(-)、H(2)O(2) 和 HO）在衰老以及许多人类疾病中起作用。超氧化物歧化酶（SOD）和谷胱甘肽过氧化物酶（GPx）是生物体内重要的抗氧化酶。SOD 催化 O(2)(-)歧化为 H(2)O(2)，GPx 催化 H(2)O(2)和其他有害过氧化物与谷胱甘肽（GSH）的还原。它们不仅在催化过程中起作用，而且相互保护，从而更有效地清除 ROS，保护细胞免受损伤，并维持 ROS 的正常代谢。为了模拟 SOD 和 GPx 的协同作用，根据天然酶结构模型，设计了一种 65 肽（65P），其中包含形成 SOD 活性中心和 GPx 催化三联体序列的肽段，在半胱氨酸营养缺陷型表达系统中表达，获得 Se-65P。通过掺入 Cu(2+)和 Zn(2+)，将 Se-65P 转化为 Se-CuZn-65P。Se-CuZn-65P 由于具有精细的双活性中心，表现出高 SOD 和 GPx 活性。通过体外模型和黄嘌呤/黄嘌呤氧化酶/Fe(2+)-诱导的线粒体损伤模型系统评估了酶模拟物的协同作用。我们期望具有协同作用的肽酶模拟物有望用于人类疾病的治疗，并有可能作为一种有效的抗氧化剂在医学上得到应用。
