Uricase and British Anti-Lewisite is uricase a zinc-proteid?

Abstract 1. 1. The activity of uricase is estimated from the velocity of the spectral change, which is caused by the enzymatic conversion of uric acid. 2. 2. A method for quantitative determination of BAL is outlined on the basis of the spectral changes which occur when the compound is oxidized by air in an alkaline medium. 3. 3. Inhibition of the action of uricase may occur in the presence of BAL, which, being oxidized itself, reduces the oxygen tension of the system. 4. 4. The activity of uricase is unaffected by dialysis of the enzyme against BAL, and is also unaffected by incubation of the enzyme with this compound. 5. 5. BAL combines instantaneously with zinc ions with the formation of a stable compound. The oxidation of BAL ceases suddenly when equivalent amounts of zinc are added. 6. 6. By dialysis of uricase against BAL a sample of the enzyme has been prepared, the specific activity of which is as high as high as that of the best preparations hitherto reported, although the zinc content is less than 0.04%. In a later experiment with larger amount of uricase the zinc content was less than 0.008%. 7. 7. The findings do not lend support to the assumption that uricase may be a zinc-proteid.