CHARACTERIZATION OF CYTOSOLIC MALIC ENZYME IN HUMAN TUMOR-CELLS

Cytosolic NADP(+)-dependent malic enzyme (ME) from human tumor cells w as characterized in detail and compared to ME from normal human tissue s produced in recombinant E, call. Kinetic properties, size as seen in SDS gels, and HPLC elution profiles of tryptic digests of human 'norm al cell' ME and NADP(+)-ME from tumor cells were identical. Thus, NADP (+)-ME found in tumor cells does not constitute a tumor-specific isofo rm as suggested by other studies but is identical to the 'housekeeping protein' predominantly expressed in human liver and white adipose tis sue.