Cyclic AMP specific, calcium independent phosphodiesterase from a malignant murine mast cell tumor

Abstract

A cAMP specific phosphodiesterase (PDE) has been identified in a malignant tumor (P815) of murine mast cells. The PDE is found primarily (85%) in the soluble fraction of the cell. This enzyme, purified approximately 10-fold by gel filtration, occurs in a single molecular and kinetic form (low K m), and is apparently not dependent on calcium and calmodulin for optimum activity. Although cGMP is hydrolyzed at only 4% of the rate of cAMP hydrolysis, this cyclic nucleotide inhibits cAMP PDE activity by 50–60% at a concentration of 25 μM.