PURIFICATION AND CHARACTERIZATION OF DNA METHYLASE FROM HL-60 CELLS

A solid leukemia sarcoma has been successfully developed after subcuta neous inoculation of the cultured human promyelocytic leukemia cells ( HL-60 cells) into unde mice. The solid leukemia sarcoma is a more plan tiful source than the cultured cells for enzymatic study and its growi ng environment is closer to that of the human body than the cultured c ells. We establish an efficient procedure or purifying HL-60 cells DNA methylase which includes: disruption of HL-60 cells by homogenization and sonication, removing the cell fragments and cellular particles by centrifuge and ultracentrifuge (105;000 g); removing endogenous DNA b y streptomycin sulfate, salting but by (NH4)(2)SO4, ion exchange chrom atography on DEAE-cellulose (DE-52), gel filtration over Sephadex G-10 0 column. The DNA methylase from HL-60 cells has been purified 204 fol d by this procedure. The purified enzyme shows a single-band on PG-PAG E. A 479-kD molecular weight of this enzyme is measured by PG-PAGE. Th e enzyme properties of HL-60 DNA methylase are also studied.