Centro de Investigación en Alimentación y Desarrollo, A. C (CIAD). Carretera a Ejido La Victoria km 0.6, PO Box 1735, Hermosillo, Sonora 83000, México.
J Biochem Mol Toxicol. 2010 Jul-Aug;24(4):218-22. doi: 10.1002/jbt.20326.
Glutathione S-transferases (GSTs) are a family of detoxifying enzymes that catalyze the conjugation of glutathione (GSH) to electrophiles, thereby increasing the solubility of xenobiotics and aiding its excretion from the cell. The present work presents the inhibition of a mu-class GST of the marine shrimp Litopenaeus vannamei by copper (Cu2+) and cadmium (Cd2+). The protein was overexpressed in bacteria and its enzymatic activity measured using 1-chloro-2,4-dinitrobenzene. The mean inhibitory concentration (IC(50)) for shrimp GST against Cu2+) was 4.77 microM and for Cd2+ was 0.39 microM. A molecular model of the protein based on the crystal structure of a maize GST bound to cadmium showed that the metal binds in the GSH-binding site by coordination with Asp and Gln residues. These results are consistent with the experimental data and suggest that sublethal concentration of metals may affect the capacity of the organism to detoxify pesticides or xenobiotics.
谷胱甘肽 S-转移酶（GSTs）是一组解毒酶，可催化谷胱甘肽（GSH）与亲电试剂的结合，从而增加外来化合物的溶解度并有助于其从细胞中排出。本工作研究了铜（Cu2+）和镉（Cd2+）对海洋虾 Litopenaeus vannamei 的 mu 类 GST 的抑制作用。该蛋白在细菌中过表达，并使用 1-氯-2,4-二硝基苯测量其酶活性。虾 GST 对 Cu2+）的半数抑制浓度（IC（50））为 4.77 microM，对 Cd2+为 0.39 microM。基于与镉结合的玉米 GST 的晶体结构的蛋白质分子模型表明，金属通过与 Asp 和 Gln 残基的配位结合在 GSH 结合位点。这些结果与实验数据一致，表明亚致死浓度的金属可能会影响生物体解毒农药或外来化合物的能力。
