重金属中毒体内解毒机理研究——金属硫蛋白在动物铜、镉中毒与解毒中的作用

STUDY ON THE MECHANISM OF DETOXIFICATION OF HEAVIER METAL POISONING IN VIVO——THE EFFECTS OF METALLOTHIONEIN ON THE TOXIFICATION AND DETOXIFICATION OF COPPER AND CADMIUM

金属硫蛋白(Metallo thioncin,MT)是动物体内泛在性蛋白质,能捕获进入体内的重金属如铜、镉等。起固定、保存重金属元素、解除离子态重金属的毒性作用,三硫钼酸钠可以使与金属硫蛋白结合的铜、镉解离,但MT的分子量不变。离开MT后的金属离子可进入血液,与白蛋白结合,使血浆铜浓度及血浆三氯醋酸(TCA)沉淀物中铜浓度升高,更多的铜则进入胆汁,经粪便排出体外。硒酸钠和亚硒酸钠有类似的作用,可使与MT结合的镉解离,并转移到结合强度较小,而分子量较大的蛋白质上,有一定的促进镉排泄的作用。因此,血浆铜及血浆TCA沉淀物中铜浓度升高,可作为监测钼诱导缺铜病早期阶段的指标,硫钼酸钠可作为绵羊、山羊铜中毒,人的Wilson氏病的特效治疗药,亦可作为鱼铜中毒时的去铜剂,甚至可望成为慢性镉中毒的去镉剂。

Metallothionein (MT) is an unique protein exsisted in variety tissues and organs. MTselectively bound heavy metal ions entered in body such as copper, cadmium, mercury etc. preserved, fixedand dctoxified the ionic heavy metals. Trithiomolybdatc might strip the copper and cadmium from MT.The ions left from MT catered mainly into bile and excreted through feces, a part of ions might enter intoblood, combined on the albumin, clcvcted the levels of plasma copper and trichloroacetic acid (TCA) insoluble copper. However, there is no change of the MT's molecular weight. Sodium selenate and selenitemight possess a similar function of striping cadmium from MT, metals left from MT were transfered intolarge molecular weight proteins which had a weakly binding strength, cadmium might be easier to be excreted. The experimental results showed here suggested that the increased copper in the plasma fractionscould be as an index for diagnosing copper deficiency induced by molybdenum in ruminants.Trithiomolybdate can be as a drug for treating copper poisoning of sheep and goats, wilson's disease andhopefully as a decadmium drug for human and animals.