| Abstract: | The possible existence of several species of DNA-dependent DNA polymerases in mammalian cells in addition to those 2 polymerases which are the smaller enzyme from nucleus and larger one from cytoplasm each having distinct characteristics, have been reported recently. In order to examine the heterogeneity of DNA polymerases in murine leukemia L1210 cells and to characterize their general properties, we have attempted to separate the DNA polymerase activities from L1210 cells. By diethylaminoethyl (DEAE)-cellulose chromatography (0.2 M-1M KCl) of the whole cell extract from L1210 solubilized by 1% Triton X-100 and 0.5 mM ethylenediaminetetraacetate (EDTA), 4 fractions with DNA-dependent DNA polymerase activities were obtained and designated as DD-1, DD-2, DD-3, and DD-4 for eluents with each corresponding concentration of 0.2, 0.3, 0.5, and 0.7 M KCl, respectively. They were distinguishable in properties such as template preference, divalent cation requirement, DNase sensitivity, isoelectric point (pI) and the behavior on the phosphocellulose chromatography. DD-1 preferred native DNA as template exhibiting similar characteristic as nuclear polymerase with low molecular weight and insensitivity to SH-inhibitors. DD-2, DD-3, and DD-4 utilized activated DNA most efficiently, while activity of DD-3 increased even in the presence of DNase 1 under the condition where the others were completely inhibited. Distribution of DNA polymerase activities in the cells is discussed briefly. |
