Acrolein-detoxifying isozymes of glutathione transferase in plants.
Acrolein-detoxifying isozymes of glutathione transferase in plants.
复制标题
植物中谷胱甘肽转移酶的丙烯醛解毒同工酶。
作者：
Mano;J.;Ishibashi;A.;Muneuchi;H.;Morita;C.;Sakai;H.;Biswas;Md. S.;Koeduka;T. and Kitajima;S.
结论丙烯醛是一种脂质衍生的高活性醛，介导植物的氧化信号和损伤。我们在植物中发现了清除丙烯醛的谷胱甘肽转移酶活性，并从菠菜中纯化了一种低kmisoase。植物受到的各种环境胁迫导致丙烯醛的产生，丙烯醛是一种由脂质过氧化物产生的高毒性醛，通过促进活性氧的形成，氧化膜脂。在哺乳动物中，丙烯醛可被α、Pi和Mu类谷胱甘肽转移酶（GST; EC 2.5.1.18）同工酶清除，但植物缺乏这些GST类。我们检测了四种植物清除丙烯醛的GST活性，并从菠菜（Spinacia oleraceaL.）叶片中纯化出具有这种活性的同工酶。经亲和层析和两个离子交换层析得到的同工酶（GST-Acr）对丙烯醛的km值为93 μM，是目前已知的植物中丙烯醛解毒酶的最小值。肽序列同源性研究表明，GST- acr属于GST Tau，是植物特异性的一类。与菠菜GST-Acr序列最接近的拟南芥agst Tau19对丙烯醛也表现出较高的催化效率。这些结果表明，GST在植物中起着丙烯醛清除剂的作用。
Main conclusionAcrolein is a lipid-derived highly reactive aldehyde, mediating oxidative signal and damage in plants. We found acrolein-scavenging glutathione transferase activity in plants and purified a lowKMisozyme from spinach.Various environmental stressors on plants cause the generation of acrolein, a highly toxic aldehyde produced from lipid peroxides, via the promotion of the formation of reactive oxygen species, which oxidize membrane lipids. In mammals, acrolein is scavenged by glutathione transferase (GST; EC 2.5.1.18) isozymes of Alpha, Pi, and Mu classes, but plants lack these GST classes. We detected the acrolein-scavenging GST activity in four species of plants, and purified an isozyme showing this activity from spinach (Spinacia oleraceaL.) leaves. The isozyme (GST-Acr), obtained after an affinity chromatography and two ion exchange chromatography steps, showed theKMvalue for acrolein 93 μM, the smallest value known for acrolein-detoxifying enzymes in plants. Peptide sequence homology search revealed that GST-Acr belongs to the GST Tau, a plant-specific class. TheArabidopsis thalianaGST Tau19, which has the closest sequence similar to spinach GST-Acr, also showed a high catalytic efficiency for acrolein. These results suggest that GST plays as a scavenger for acrolein in plants.