锌_7-金属硫蛋白与镉_7-金属硫蛋白抗羟自由基保护线粒体效应  

Protection of Mitochondria from Free Hydroxyls by Zn7and Cd7 Metallothioneins

作　　者：葛淑君[1] 程时[1] 仲崇霞 侯琳[1] 

机构地区：[1]北京医科大学生物物理系

出　　处：《生物化学与生物物理学报》1998年第3期267-271,共5页

基　　金：国家自然科学基金

摘　　要：制备了Ｚｎ７－与Ｃｄ７－金属硫蛋白。分离出大鼠心肌线粒体。用电子自旋共振自旋标记方法测定线粒体膜脂流动性及膜蛋白构象、运动性。分析了线粒体Ｃａ２＋－Ｍｇ２＋－ＡＴＰ酶活性及４５Ｃａ摄入。羟自由基损伤使线粒体膜脂流动性下降，膜蛋白构象改变及运动性降低，线粒体Ｃａ２＋－Ｍｇ２＋－ＡＴＰ酶活性降低及４５Ｃａ摄入活性下降。Ｚｎ７－金属硫蛋白与Ｃｄ７－金属硫蛋白均有抗羟自由基、保护心肌线粒体的作用，且Ｚｎ７－金属硫蛋白的作用比Ｃｄ７－金属硫蛋白的作用更明显。原因是去金属蛋白对Ｃｄ２＋的亲和力比对Ｚｎ２＋高１００００倍，因而在近ｐＨ中性的环境中，Ｚｎ７－金属硫蛋白将释放更多Ｚｎ２＋，并暴露较多的还原态巯基。Zn7and Cd7metallothioneins were prepared. Mitochondria were isolated from rat hearts. Mitochondria lipid fluidity, protein conformation and mobility were determined by using ESR spin label. Ca2+Mg2+ATPase activity and 45Ca uptake activity were assayed. It was found that, after being damaged by hydroxyl radicals, mitochondria lipid fluidity and protein mobility decreased, protein conformation changed and mitochondria Ca2+Mg2+ATPase activity, 45Ca uptake activity were inhibited. Both Zn7 and Cd7metallothioneins could antagonize hydroxyl radicals and protect myocardial mitochondria. However, this effect of Zn7 metallothiionein was stronger than that of Cd7 metallothionein, because the apometallothionein has about 10 000 fold higher affinity for Cd than for Zn, so, Zn7 metallothionein would release more Zn2+ and more reduced thiol groups would be revealed.

关 键 词：金属硫蛋白 线粒体 羟自由基 镉 锌 

分 类 号：Q513[生物学—生物化学]