Effect of reductones on cyclic 3', 5'-adenosine monophosphate phosphodiesterase.

The effect of some reductones such as ascorbic acid (AsA), triose reductone (TR), epinephrine (Ep) and their derivatives on cyclic 3', 5'-adenosine monophosphate phosphodiesterase (cAMP PDE) was studied in the presence or absence of Cu2+. AsA, TR, Ep and the reductones related to them inhibited cAMP PDE activity. Among the reductones, TR showed the highest inhibition. AsA, 5-methyl-3,4-dihydroxytetrone, pyrocatechol, p-hydroxyquinone and resorcinol had a relatively high inhibiting activity. The type of inhibition of AsA, TR and Ep was uncompetitive, competitive and noncompetitive, respectively. Cu2+ enhanced the inhibitory action of the reductones markedly and altered the type of inhibition of the reductones.