[The process of cyclic adenosine-3',5'-monophosphate phosphodiesterase activation by 2',5'-oligoadenylate]

The effect of 2',5'-oligoisoadenylate on the activity of cyclic nucleotide (cAMP and cGMP) phosphodiesterase in cell (NIH 3T3) lysate was studied. It was shown that the activation of cAMP phosphodiesterase by 2',5'-oligoisoadenylate occurs via a non-competitive mechanism, i.e. the activator does not affect cAMP binding to phosphodiesterase but increases the rate constant of the reaction product (k2) formation. The kinetic parameters of this reaction, i.e. the values of activation constant, K alpha, and parameter beta characterizing the increase in the enzyme turnover number, were determined. 2'5'-Oligoisoadenylate was shown to cause specific activation of cAMP hydrolysis without affecting the activity of cGMP phosphodiesterase.