The distribution of soluble copper- and zinc-binding proteins in goat liver.

The distribution of copper and zinc in the soluble proteins from goat liver after gel filtration were determined. Samples from normal slaughtered animals as well as from experimentally copper-loaded goats were tested. The copper- and zinc-binding proteins were mainly separated into 3 different fractions. The approximate molecular weights were greater than 65,000, 35,000 and 10,000. Varying amounts of zinc were eluted in a fourth fraction of molecular weight less than 2000. The results indicate that the distribution of copper and zinc among soluble metal-binding proteins are highly dependent on the total liver zinc concentration. In the majority of samples, with zinc levels within 20 to 45 microgram/g wet weight, the dominating copper- and zinc-binding protein fraction was the high-molecular weight fraction. This did not seem to be influenced by the total liver copper level. In the samples with high total zinc levels (greater than 60 microgram/g w.w.) there was a shift in protein distribution of both metals toward the low-molecular weight fractions.