具有谷胱甘肽过氧化物酶活力的含硒三肽

Tripeptide Containing Selenium with Glutathione Peroxidase Activity

合成了由硒代半胱氨酸(U)、谷氨酰胺(Q)和色氨酸(W)组成的QUW,QWU,WQU,WUQ,UWQ和UQW 6个具有谷胱甘肽过氧化物酶(GPx)活力的含硒三肽;采用双酶偶联法进行了GPx活力测定和稳态动力学分析;通过噻唑蓝(MTT)比色法、划痕愈合实验和Western blot技术表征了含硒三肽对肝癌Hep G2细胞生长和迁移能力的影响.结果表明,当U位于氨基端时,含硒三肽的GPx活力高于U位于中间位置或者羧基端时.UWQ催化谷胱甘肽(GSH)还原H2O2的活力最高,其催化机制为乒乓机制.UWQ可使Hep G2细胞运动能力减弱,降低肝癌细胞的浸润转移能力.

Six selenium-containing tripeptides（ QUW,QWU,WQU,WUQ,UWQ and UQW） were synthesized by solid-phase synthesis technology based on the catalytic triad of native glutathione peroxidase（ GPx）.The GPx activities and the kinetics of the tripeptide were determined by the enzyme coupling method. The effects of tripeptide on Hep G2 cells growth and migration were assessed using the 3-（ 4,5-dimethylthiazol-2-yl）-2,5-diphenyltetrazolium bromide（ MTT） assay,wound assay and Western blot method. The results showed that the GPx activity of the tripeptide with U at the amino terminal was higher than that of U at the middle position or the carboxyl terminal. Among the six tripeptide,the activity of UWQ catalyzed by glutathione（ GSH）reduced by hydrogen peroxide（ H_2O_2） was higher than those of other tripeptides,and its catalytic mechanism was Ping-Pong mechanism. UWQ can dosedependently discrease migration speed of Hep G2 cells to exercise,and reduce the invasion and metastasis of Hep G2 cells.