An improved purification procedure for sulfite oxidase from bovine liver.

Sulfite oxidase (Sulfite:O2 oxidoreductase, EC 1.8.3.1) has been purified 2,440-fold from bovine liver. The procedure developed was used to isolate the enzyme from 1,000 g of liver and permitted the rapid isolation of enzyme with a very high specific activity (40,405 mU/mg). The enzyme preparations obtained have been characterized by electrophoretic and spectrophotometric analysis and the molecular mass and the Stokes radius of the enzyme have been determined.     

Purine catabolism in rat brain (author's transl)

In soluble rat brain fraction, the specific activities of purine nucleoside phosphorylase, guanine deaminase, 5'Nucleotidase and adenosine deaminase, decrease in their mentioned order. A kinetic parameter comparison between these enzymes shows that 5'Nucleotidase with AMP has the lowest KM and the greatest Vmax values, while purine nucleoside phosphorylase has its lowest KM and its greatest Vmax values with guanosine and with inosine, respectively. The enzymes activity is not modified by the metabolic intermediates differently from their own reaction products which behave as competitive inhibitors.