[Influence of age on the 5'-nucleotidase activity of the plasma membrane of rat liver: note II].

The effect of age on the kinetic properties of the plasma membrane 5'-nucleotidase in liver cells is studied. Vmax and Km and the discontinuity temperature are lower in the 230 +/- 15 days old rats. It appears that lipids do not affect the isotermic kinetic of the enzyme, while the decrease in the discontinuity temperature in the 230 +/- 15 days old animals might be related to the higher percent of insaturated fatty acids.