Mixed function oxidase enzymes in human normal granulocytes and chronic myeloid leukemia cells. I. Detection and estimation.

Subcellular fractions prepared from human normal granulocytes and leukemic cells from patients with chronic myeloid leukemia (CML), were examined for 7-ethoxycoumarin O-deethylase activity as well as cytochrome P-450 and cytochrome b5 contents. The average 7-ethoxycoumarin O-deethylase activity was found to be significantly increased in all the fractions of CML cells when compared to the corresponding fractions of the normal granulocytes. The CML cells also differed from the normal cells by exhibiting decreased levels of both cytochrome P-450 and cytochrome b5. Examination of the microsomal and cytosolic fractions of both normal granulocytes and CML cells showed distribution of 7-ethoxycoumarin O-deethylase, cytochrome P-450, and cytochrome b5 in both the fractions. Such distribution seems to be unique for human leukocytes. Solubilization of protein in the postmitochondrial (S1) fractions of both the cell types with sodium cholate in the presence of 20% glycerol and further fractionation with 10% polyethylene glycol 6000 (PEG-6000) yielded a partially purified preparation with enriched 7-ethoxycoumarin O-deethylase activity and cytochrome P-450 as well as cytochrome b5 contents.