REGULATION OF RAT-KIDNEY CORTEX FRUCTOSE-1,6-BISPHOSPHATASE ACTIVITY .2. EFFECTS OF ADENINE-NUCLEOTIDES

1. The native rat-kidney cortex Fructose-1,6-bisphosphatase is differe ntially regulated by adenine nucleotides in the presence of divalent c ations. 2. Binding of AMP and ADP to the enzyme is co-operative. The i nhibition by both nucleotides show an uncompetitive mechanism AMP bein g the most efficient inhibitor. 3. Mg2+ decreases the inhibition produ ced by AMP and ADP by enhancing their I-0.5 and completely annulates t he inhibitory effect of ATP. 4. In the presence of Mn2+ ADP behaves as an inhibitor but no inhibition is evident with AMP, suggesting the ex istence of different allosteric sites for each nucleotide.