Aniya Y, Anders M W
Laboratory of Physiology and Pharmacology, School of Health Sciences, University of the Ryukyus, Okinawa, Japan.
Arch Biochem Biophys. 1989 Apr;270(1):330-4. doi: 10.1016/0003-9861(89)90035-0.
The regulation of purified glutathione S-transferase from rat liver microsomes was studied by examining the effects of various sulfhydryl reagents on enzyme activity with 1-chloro-2,4-dinitrobenzene as the substrate. Diamide (4 mM), cystamine (5 mM), and N-ethylmaleimide (1 mM) increased the microsomal glutathione S-transferase activity by 3-, 2-, and 10-fold, respectively, in absence of glutathione; glutathione disulfide had no effect. In presence of glutathione, microsomal glutathione S-transferase activity was increased 10-fold by diamide (0.5 mM), but the activation of the transferase by N-ethylmaleimide or cystamine was only slightly affected by presence of glutathione. The activation of microsomal glutathione S-transferase by diamide or cystamine was reversed by the addition of dithiothreitol. Glutathione disulfide increased microsomal glutathione S-transferase activity only when membrane-bound enzyme was used. These results indicate that microsomal glutathione S-transferase activity may be regulated by reversible thiol/disulfide exchange and that mixed disulfide formation of the microsomal glutathione S-transferase with glutathione disulfide may be catalyzed enzymatically in vivo.
通过检测各种巯基试剂对以1-氯-2,4-二硝基苯为底物的酶活性的影响，研究了大鼠肝脏微粒体中纯化的谷胱甘肽S-转移酶的调节作用。在不存在谷胱甘肽的情况下，二酰胺（4 mM）、胱胺（5 mM）和N-乙基马来酰亚胺（1 mM）分别使微粒体谷胱甘肽S-转移酶活性提高了3倍、2倍和10倍；谷胱甘肽二硫化物没有影响。在存在谷胱甘肽的情况下，二酰胺（0.5 mM）使微粒体谷胱甘肽S-转移酶活性提高了10倍，但谷胱甘肽的存在对N-乙基马来酰亚胺或胱胺对转移酶的激活作用影响较小。加入二硫苏糖醇可逆转二酰胺或胱胺对微粒体谷胱甘肽S-转移酶的激活作用。只有在使用膜结合酶时，谷胱甘肽二硫化物才会增加微粒体谷胱甘肽S-转移酶的活性。这些结果表明，微粒体谷胱甘肽S-转移酶活性可能受可逆的巯基/二硫键交换调节，并且微粒体谷胱甘肽S-转移酶与谷胱甘肽二硫化物形成的混合二硫键可能在体内由酶催化。
