Mammalian metallothioneins (MT’s) are small molecular weight proteins consisting of 20 cysteine thiolates which serve to bind 7 divalent metal ions.  It has been postulated that MT plays a pivotal role in the regulation of cellular pools of metal including zinc, and may be the regulated factor controlling the activation and innactivation of certain zinc dependent enzymes.  It is hypothesized that MT donates zinc to apo-metalloproteins such as alkaline phosphatase via glutathione which acts as an intermediary transport molecule in this process.  In order to test this hypothesis it is necessary to generate apo-metallothionein and reconstitute the protein using a form of metal, such as a radio or stable isotope, that can be distinguished from extrinsic sources of the metal.  Preparation of the purified apo-mt product was accomplished by acidification and pressure dialysis.  Quantification of metal removal was determined by HPLC-ICP-MS from the integrated areas of FIA injections constituting 2.5 ng of metal.  The results showed a 83.7% reduction in copper, a 92.4% reduction cadmium, a 100% reduction of zinc, and a 100% reduction in molybdenum.