Properties and sidedness of 5'-nucleotidase in rat red cell ghosts.

The occurrence of a Mg++-activated 5'-AMPase activity in rat ghosts is demonstrated. This activity is inhibited by the alpha, beta-methyleneadenosine 5'-diphosphate, a specific inhibitor of 5'-nucleotidase. The enzyme has an apparent Km of approximately 90 microM, and is located on the exterior side of the plasma membrane.

[Influence of thyroid condition on 5'-nucleotidase activity of the plasma membrane in the rat liver]. / Influenza dello stato tiroideo sull'attivita' 5'-nucleotidasica della membrana plasmatica nel fegato di ratto.

The effect of thyroid hormones on the Kinetic properties of plasmatic membrane 5'-nucleotidase in rat liver is studied. The Vmax and Km which increased significatively a week after thyroidectomy were reported to the normal values by the chronic administration of T3. The decrease in Vmax and Km observed five weeks after thyroid ablation may be attributed to secondary effects occurring with time.

[Influence of age on the 5'-nucleotidase activity of the plasma membrane of rat liver: note II]. / Influenza dell'eta' sull'attivita' della 5'-nucleotidasi associata alla membrana plasmatica di fegato di ratto: nota 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.

[Influence of the age on 5'-nucleotidase activity associated with the rat liver plasma membrane]. / Influenza dell'età sull'attività della 5'-nucleotidasi associata alla membrana plasmatica da fegato di ratto.

The influence of age on the isothermic and temperature-induced kinetics of the plasma membrane 5'-nucleotidase was studied in rat liver. The apparent Km values increased with age, while the Vmax, the temperature discontinuity and the Ex above and below the max break were unaffected.