Cyclic 3':5'-adenosine monophosphate phosphodiesterase and cyclic 3':5'-guanosine monophosphate phosphodiesterase of normal granulocytes and granulocytes of chronic myelogenous leukaemia.

Normal human neutrophilic granulocytes and granulocytes of chronic myelogenous leukaemia (CML) were shown to possess only the "high Km type" isoenzyme of cAMP-phosphodiesterase. The properties of this enzyme are similar in both normal and CML granulocytes. cGMP-phosphodiesterase in human granulocytes was found to be composed of "high Km type" and "low Km type" isoenzymes. The high Km cGMP-phosphodiesterase of CML granulocytes showed a considerably lower apparent Km and Vm value than those in normal neutrophilic granulocytes.