Metallothionein occurs in roots of Agrostis tolerant to excess copper
Metallothionein occurs in roots of Agrostis tolerant to excess copper
复制标题
金属硫蛋白存在于耐过量铜的剪股草根中
作者：
W. E. Rauser;N. Curvetto
金属硫蛋白在动物金属代谢中具有重要作用。这些低分子量蛋白质具有高含量的半胱氨酸基残基（高达33%），可以在巯基络合物中结合锌、铜、镉、汞或银等金属1。在正常情况下，动物组织中金属硫蛋白的浓度较低，但在给予金属2 - 4后会增加，这一反应与它们在解毒机制中的作用一致2,5,6。不同的植物基因型表现出对过量金属的耐受性，jowett8提出这些基因型含有能够进行特定金属螯合的化合物。金属硫蛋白可以起到这样的作用。我们在这里报道，铜硫蛋白出现在对过量铜耐受的巨地农（agrostis giganteoth）无性系的根部。这是第一次在维管植物中明确地证明金属硫蛋白。这些异常蛋白可能与植物的金属代谢有关，对阐明植物的金属耐受机制具有重要意义。
Metallothioneins have an important function in metal metabolism in animals1. These low molecular weight proteins have high contents of half-cystinyl residues (up to 33%) which can bind metals such as Zn, Cu, Cd, Hg or Ag in mercaptide complexes1. In normal conditions animal tissues have low concentrations of metallothioneins, but these increase on administration of metal2–4, a reaction which is consistent with their suggested role in detoxification mechanisms2,5,6. Various plant genotypes exhibit tolerance to excesses of metals7, and Jowett8proposed that such genotypes contain compounds capable of specific metal chelation. Metallothioneins could serve such a role. We report here that copper-thionein occurs in the roots of a clone ofAgrostis giganteaRoth tolerant to excess copper9. This is the first unequivocal demonstration of a metallothionein in a vascular plant. These unusual proteins may have a role in metal metabolism in plants and could be important in the elucidation of the mechanism of metal tolerance.