Ohtake H, Koga M
Biochem J. 1979 Dec 1;183(3):683-90. doi: 10.1042/bj1830683.
Zn-binding protein in liver of the partially hepatectomized rat was purified by column chromatography on Sephadex G-75 and DEAE-cellulose. Homogeneity was judged by polyacrylamide-disc-gel electrophoresis. The molecular weight determined by gel-permeation chromatography in 6 M-guanidine hydrochloride was 6700. This value is in good agreement with the molecular weight calculated from the amino acid composition, which was 6073. Zn-binding protein was composed of 61 amino acid residues, and the distinctive features include an extremely high content of cysteine, which accounted for one-third of the total amino acid residues, and an absolute absence of aromatic amino acids as well as of histidine, leucine and arginine. The amino acid composition was similar to that of the metallothioneins previously isolated from rat liver and mouse liver. These observations suggest that the Zn-binding protein can be classified as a type of metallothionein. Zn-binding protein contained 8.2g-atoms of zinc per mol and traces of copper, but no cadmium. The molar ratio of thiol groups to zinc was calculated to be 2.5:1. Possible roles of this Zn-binding protein in the transport and storage of zinc in the liver are discussed.
通过Sephadex G - 75和DEAE - 纤维素柱色谱法对部分肝切除大鼠肝脏中的锌结合蛋白进行了纯化。通过聚丙烯酰胺圆盘凝胶电泳判断其均一性。在6M盐酸胍中通过凝胶渗透色谱法测定的分子量为6700。该值与根据氨基酸组成计算出的分子量6073非常吻合。锌结合蛋白由61个氨基酸残基组成，其显著特征包括半胱氨酸含量极高，占总氨基酸残基的三分之一，并且绝对不含芳香族氨基酸以及组氨酸、亮氨酸和精氨酸。其氨基酸组成与先前从大鼠肝脏和小鼠肝脏中分离出的金属硫蛋白相似。这些观察结果表明，锌结合蛋白可归类为一种金属硫蛋白。锌结合蛋白每摩尔含有8.2克原子的锌以及微量的铜，但不含镉。巯基与锌的摩尔比经计算为2.5:1。本文讨论了这种锌结合蛋白在肝脏中锌的运输和储存中的可能作用。
