Activities and some properties of 5'nucleotidase in isolated hamster fat cells

Kinetic parameters and the possible cellular location of 5'nucleotidase were studied in isolated hamster fat cells. Measurements of the enzyme were performed using 5'IMP instead of 5'AMP as substrate. The apparent Vmax and Km values obtained support the view that two forms of 5'nucleotidase, having different affinities, are present in hamster fat cells. The major form was located in the outer surface of plasma membrane and the other one inside the cell. The effects of ADP, adenosine and inosine on the enzyme were studied. ADP and adenosine were competitive inhibitors. The enzyme was not modified by inosine.