Aniya Y, Daido A
Laboratory of Physiology and Pharmacology, School of Health Sciences, Faculty of Medicine, University of the Ryukyus, Okinawa, Japan.
Jpn J Pharmacol. 1993 May;62(1):9-14. doi: 10.1254/jjp.62.9.
The effect of t-butyl hydroperoxide (t-BuOOH), cumene hydroperoxide (CuOOH) or linoleic acid hydroperoxide (linoleic-OOH) on liver microsomal glutathione S-transferase of rats was studied in vitro. When microsomes were incubated with either 100 microM t-BuOOH or 25 microM CuOOH, glutathione S-transferase activity was increased 1.5-fold; activity was further increased to 2.2-fold in the presence of small amounts of glutathione. The same amounts of dithiothreitol or cysteine did not enhance the t-BuOOH or CuOOH-induced increase in transferase activity. The transferase activity was also increased 1.4-fold by 10 microM linoleic-OOH plus 1 microM glutathione. The increase in microsomal glutathione S-transferase activity after treatment of microsomes with t-BuOOH in the presence of glutathione was completely reversed by addition of dithiothreitol, whereas the activation of the transferase caused by t-BuOOH in the absence of glutathione was not reversed. Although microsomal glutathione S-transferase also possesses glutathione peroxidase activity, only transferase activity was increased by t-BuOOH in either the presence or absence of glutathione. These data indicate that microsomal glutathione S-transferase is activated by organic hydroperoxides in either the absence or presence of small amounts of glutathione, suggesting an activation of the transferase by thiol oxidation of the cysteine residue.
体外研究了叔丁基过氧化氢（t-BuOOH）、异丙苯过氧化氢（CuOOH）或亚油酸过氧化氢（亚油酸-OOH）对大鼠肝脏微粒体谷胱甘肽S-转移酶的影响。当微粒体与100 microM的t-BuOOH或25 microM的CuOOH孵育时，谷胱甘肽S-转移酶活性增加了1.5倍；在存在少量谷胱甘肽的情况下，活性进一步增加到2.2倍。相同量的二硫苏糖醇或半胱氨酸不会增强t-BuOOH或CuOOH诱导的转移酶活性增加。10 microM的亚油酸-OOH加1 microM的谷胱甘肽也使转移酶活性增加了1.4倍。在谷胱甘肽存在的情况下，用t-BuOOH处理微粒体后微粒体谷胱甘肽S-转移酶活性的增加通过添加二硫苏糖醇完全逆转，而在不存在谷胱甘肽的情况下t-BuOOH引起的转移酶激活没有被逆转。尽管微粒体谷胱甘肽S-转移酶也具有谷胱甘肽过氧化物酶活性，但无论是否存在谷胱甘肽，t-BuOOH都只会增加转移酶活性。这些数据表明，微粒体谷胱甘肽S-转移酶在不存在或存在少量谷胱甘肽的情况下均被有机过氧化物激活，提示半胱氨酸残基的硫醇氧化激活了该转移酶。
