[Kinetic properties and regulation of cyclic nucleotide phosphodiesterases in lymphoid cells].

cGMP-dependent cyclic nucleotide phosphodiesterases have been isolated from spleen lymphocytes and the whole mice spleen and shown to possess identical properties. Two structure analogues of cAMP and cGMP, viz. N6,O2'-dibutyryl-cAMP and N2,O2'-dibutyryl-cGMP, were used to investigate the properties of the phosphodiesterase and found to inhibit hydrolysis of both cAMP and cGMP. This inhibition did not affect the cGMP activation constant. Existence of two different centres of catalytic and regulatory types in cGMP-stimulated phosphodiesterase is suggested.