No abstract

1. A study has been made by gel-filtration techniques of the soluble copper- and zinc-binding proteins in livers from calves and sheep of widely differing Cu and Zn status.2. Cu and Zn generally occurred together in three main fractions, with approximate molecular weights of > 75000, 35000 and 12000, and Zn also in one other fraction with molecular weight about 65000. The distribution of the metals between these fractions was variable and dependent on both the Cu and Zn status of the animals.3. Zn was usually absent from the low-molecular-weight fraction in Zn-deficient or high-Cu livers, with Cu also being absent in the former instance.4. The fraction with molecular weight of 35000 was tentatively identified as hepatocuprein. It generally accounted for only 4% of the total hepatic Cu except in Cu-deficient livers.5. The possible relationship of these findings to the mutual antagonism between Cu and Zn is discussed.

1. A metal-binding fraction with a molecular weight of about 12000 in calf and sheep liver has been characterized as a metallothionein-like protein.2. The combined concentrations of copper and zinc in the fraction (as μg/g liver) are a direct function of liver Zn concentration.3. The relative proportions of Cu and Zn in the fraction are dependent on the Cu: Zn ratio in the liver.4. These findings may be relevant to the mutual interaction between Cu and Zn.