Mosialou E, Piemonte F, Andersson C, Vos R M, van Bladeren P J, Morgenstern R
Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden.
Arch Biochem Biophys. 1995 Jul 10;320(2):210-6. doi: 10.1016/0003-9861(95)90002-0.
Rat liver microsomal glutathione transferase was found to display glutathione peroxidase activity toward a variety of oxidized lipids. 1-Linoleoyl-2-palmitoyl phosphatidylcholine hydroperoxide, 2-linoleoyl-1-palmitoyl phosphatidylcholine hydroperoxide, 2-linoleoyl-1-palmitoyl phosphatidylethanolamine hydroperoxide, and cholesteryl linoleate hydroperoxide all served as substrates (0.02, 0.04, 0.02, and 0.02 mumol/min mg, respectively). The phospholipid hydroperoxide glutathione peroxidase activity of the enzyme was found not to require detergent and increased when liposomes containing peroxidized phospholipid were fused with liposomes containing microsomal glutathione transferase. Methyl linoleate ozonide serves as a very efficient substrate for the microsomal glutathione transferase. The unactivated and N-ethylmaleimide-activated enzyme displayed specific activities of 0.74 and 5.9 mumol/min mg, respectively. Upon examination of a series of 4-hydroxyalk-2-enals it was found that the catalytic efficiency of the enzyme increases from the 4-hydroxyhept-2-enal up to the 4-hydroxytetradec-2-enal. The specific activities with the various 4-hydroxyalk-2-enals tested varied between 0.28 and 0.95 mumol/min mg. The phospholipid dependence of the microsomal glutathione transferase was examined in proteoliposomes formed by cholate dialysis. Phosphatidyl choline, phosphatidyl serine, phosphatidyl ethanolamine, and rat liver microsomal phospholipids could all be used successfully to reconstitute the enzyme. In conclusion, microsomal glutathione transferase can detoxify a number of lipid peroxidation products as well as a fatty acid ozonide. The results imply a protective role for the enzyme under conditions of oxidative stress.
研究发现，大鼠肝脏微粒体谷胱甘肽转移酶对多种氧化脂质具有谷胱甘肽过氧化物酶活性。1-亚油酰基-2-棕榈酰基磷脂酰胆碱氢过氧化物、2-亚油酰基-1-棕榈酰基磷脂酰胆碱氢过氧化物、2-亚油酰基-1-棕榈酰基磷脂酰乙醇胺氢过氧化物和亚油酸胆固醇酯氢过氧化物均作为底物（分别为0.02、0.04、0.02和0.02 μmol/分钟·毫克）。该酶的磷脂氢过氧化物谷胱甘肽过氧化物酶活性不需要去污剂，并且当含有过氧化磷脂的脂质体与含有微粒体谷胱甘肽转移酶的脂质体融合时，活性会增加。亚油酸甲酯臭氧化物是微粒体谷胱甘肽转移酶的一种非常有效的底物。未活化和N-乙基马来酰亚胺活化的酶的比活性分别为0.74和5.9 μmol/分钟·毫克。在研究一系列4-羟基alk-2-烯醛时发现，该酶的催化效率从4-羟基庚-2-烯醛到4-羟基十四碳-2-烯醛逐渐增加。所测试的各种4-羟基alk-2-烯醛的比活性在0.28至0.95 μmol/分钟·毫克之间变化。通过胆酸盐透析形成的蛋白脂质体中检测了微粒体谷胱甘肽转移酶对磷脂的依赖性。磷脂酰胆碱、磷脂酰丝氨酸、磷脂酰乙醇胺和大鼠肝脏微粒体磷脂均可成功用于重构该酶。总之，微粒体谷胱甘肽转移酶可以解毒多种脂质过氧化产物以及一种脂肪酸臭氧化物。结果表明该酶在氧化应激条件下具有保护作用。
