Binders of intravenously administered 65-zinc in rat liver cytoplasm.

The fate of an i.v. injected trace dose of 65Zn2+ in the rat, was studied over a period of 10 days after injection. Tissue distributions were determined and a special study was made of 65Zn binders in liver cytoplasm. A total of 6 65Zn-binding fractions were observed in liver cytoplasm with apparent molecular weights of about 113,000, 66,400, 47,400, 29,000, 23,000 and 11,400. A time study showed that 4 hours after the injection the most prominent cytoplasmatic 65Zn binders are the 113,000, 66,400 and 23,000 molecular weight fractions. A tentative identification of the main Zn binders in the six 65Zn fractions is given, using the collected data regarding their apparent molecular weight, time dependent prominence and content of stable Zn.