Riordan J R, Richards V
J Biol Chem. 1980 Jun 10;255(11):5380-3.
Metallothionein was purified under anaerobic conditions from livers of human fetuses ranging from 19 weeks gestational age to term. Homogeneous metallothionein obtained in the absence of reducing agents from the soluble fraction of the tissue which contained 24% and 85% of the total liver copper and zinc, respectively, had less than 1 g atom of copper and about 3.1 g atoms of zinc/mol. Extraction with 1% 2-mercaptoethanol of the insoluble fraction of the tissue (containing 76% and 15% of the liver copper and zinc, respectively) yielded a metallothionein with approximately 2.5 g atoms of copper and 1.3 g atoms of zinc. When the whole tissue was extracted similarly by the procedure of Rydén and Deutsch ((1978) J. Biol. Chem. 253, 519), nearly equal proportions of the two metals were obtained in the soluble fraction from which metallothionein, with about 3.0 g atoms of zinc and 1.5 g atoms of copper, was purified. Thus, zinc- and copper-rich forms of metallothionein are differently distributed between the soluble and insoluble fractions of fetal liver. Nevertheless, the predominant metal in metallothionein of human fetal liver is zinc as is the case in the adult; significant amounts of copper are also present, consistent with the elevated quantity of this metal in the fetal tissue relative to the adult. Cadmium was not detected. Zinc is much more easily removed from the protein than is copper.
在无氧条件下，从妊娠19周龄至足月的人类胎儿肝脏中纯化金属硫蛋白。在无还原剂的情况下，从组织的可溶部分获得的均一金属硫蛋白，分别含有肝脏总铜和锌的24%和85%，每摩尔含铜少于1克原子，锌约为3.1克原子。用1% 2-巯基乙醇提取组织的不溶部分（分别含肝脏铜和锌的76%和15%），得到的金属硫蛋白约含2.5克原子铜和1.3克原子锌。当按照Rydén和Deutsch（(1978) J. Biol. Chem. 253, 519）的方法类似地提取整个组织时，在可溶部分获得了几乎等量的两种金属，从中纯化出含约3.0克原子锌和1.5克原子铜的金属硫蛋白。因此，富含锌和铜的金属硫蛋白在胎儿肝脏的可溶部分和不溶部分中分布不同。然而，与成人情况一样，人类胎儿肝脏金属硫蛋白中的主要金属是锌；也存在大量铜，这与胎儿组织中该金属相对于成人的含量升高一致。未检测到镉。锌比铜更容易从蛋白质中去除。
