Epiphyseal Cartilage Cyclic Nucleotide Phosphodiesterase: Partial Purification and Kinetic Characteristics of Multiple Enzymes

Summary

Partial purification of chicken epiphyseal PDE activity by centrifugation and column chromatography has defined two distinct peaks of PDE activity. The faster eluting peak (I) has a higher apparent K_m for cyclic AMP than the slower eluting major peak (II_s and II). Peak I has greater activity towards cyclic AMP as a substrate than towards cyclic GMP but does use both substrates. Peak I is not inhibited by T-3 or indomethacin at physiological concentrations. Substrates studies demonstrate the presence of at least two overlapping PDE species in the major peak (II_s and II). There is suggestive evidence that indomethacin is a more potent inhibitor of peak II_s which can use either cyclic AMP or cyclic GMP as substrates, whereas T-3 is a more potent inhibitor of fractions eluting where the enzyme only has activity with cyclic AMP.