Inhibition of adenylate cyclase by the 2',3'-dialdehyde of adenosine triphosphate.
The periodate-oxidized analog of ATP, 2',3'-dialATP, competitively inhibited bovine brain and rat liver adenylate cyclase. The apparent Ki for inhibition of brain adenylate cyclase by 2',3'-dialATP was 196 microM in the presence of Mg2+ and 37 microM in the presence of Mn2+. The Ki values for inhibition of rat liver adenylate cyclase by 2',3'-dialATP were 48 and 30 microM in the presence of Mg2+; and Mn2+, respectively. Adenylate cyclase activity was irreversibly inactivated by 2'3'-dialATP in the presence of NaCNBH3 and the kinetics for loss in enzyme activity were pseudo-first order. Both ATP and Tris protected adenylate cyclase from irreversible inhibition by 2',3'-dialATP and NaCNBH3. It is proposed that 2',3'-dialATP forms a Schiff's base with an amino group at the active site of the enzyme and that Na-CNBH3 reduction of this Schiff's base causes irreversible modification of the catalytic subunit. The Km for 2',3'-dialATP inactivation, the maximal rate constant of inactivation, and protection of the enzyme by ATP were not affected by the presence or absence of free Mg2+. These data indicate that a divalent cation is not required for binding of 2',3'-dialATP to the active site of adenylate cyclase.
D000255:Adenosine Triphosphate / Q000031:analogs & derivatives* / Q000494:pharmacology; D000067956:Adenylyl Cyclase Inhibitors; D000818:Animals; D002417:Cattle; D002462:Cell Membrane / Q000201:enzymology; D002540:Cerebral Cortex / Q000201:enzymology*; D004492:Edetic Acid / Q000494:pharmacology; D007700:Kinetics; D008099:Liver / Q000201:enzymology*; D008274:Magnesium / Q000494:pharmacology; D008345:Manganese / Q000494:pharmacology; D011485:Protein Binding; D051381:Rats
D000067956:Adenylyl Cyclase Inhibitors; D008345:Manganese; C017199:2',3'-dialdehyde ATP; D000255:Adenosine Triphosphate; D004492:Edetic Acid; D008274:Magnesium