Separation of three cyclic-nucleotide-phosphodiesterases from bovine aorta.

Three distinct forms of cyclic-nucleotide-phosphodiesterases were separated and purified from the media layer of bovine aorta using two successive DEAE-cellulose column chromatographies. Form A hydrolyzed both cAMP and cGMP with similar K_m and V_max and was sensitive to the calcium dependent protein activator; its activity on both substrates was inhibited by cIMP. Form B hydrolyzed specifically cGMP, was insensitive to the activator but was slightly stimulated in a proteinaceous medium; it was inhibited by cIMP. Form C was specific for cAMP and was insensitive to the activator and to a proteinaceous medium; it was poorly inhibited by cIMP.