Uricase from fish liver: isolation and some properties

The uricase (urate: oxygen oxidoreducase EC.1.7.3.3) activities in livers from rainbow trout, mackerel, lake trout, catfish, shark and tilapia were 1000, 1180, 920, 630, 490 and 420 units (n moles uric acid oxidized mg-1 protein min-1) per gram liver, respectively. The enzyme from lake trout was purified twenty fold by ammonium sulfate precipitation, protamine sulfate treatment and Sephacryl S-200 column chromatography. SDS-polyacrylamide gel-electrophoresis indicated an oligomeric enzyme containing subunits of 32,500 daltons. The pH optimum was 8.8 but the enzyme had a relatively broad pH activity profile between pH 7.0-9.5. Apparent Km and Vmax values of 80 microM and greater than 1000 was obtained for the trout liver enzyme.