Abstract
HeLa cell DNA-dependent DNA polymerase I, a low molecular weight enzyme of 40,000 to 50,000, has been compared to DNA-dependent DNA polymerase II, a high molecular weight enzyme. Inhibiting antiserum prepared against cytoplasmic DNA polymerase II does not inhibit DNA polymerase I. DNA polymerase II, whether isolated from the nucleus or cytoplasm, shows the same inhibition pattern by antiserum. A DNA polymerase II, obtained from cultured Chinese hamster cells, is also partially inhibited by the HeLa DNA polymerase II antiserum. HeLa DNA polymerase II sediments as one band of approximately 6.5 S (122,000 daltons) in 0.125 m (NH4)2SO4. At a lower salt concentration (0.01 m ), larger aggregates of 10.3 S and 11.7 S are seen. At neither salt concentration is there any DNA polymerase activity sedimenting in the 3 to 4 S region where DNA polymerase I is found.
Highlights
Hecht [8] has reported that a high molecular weight (6 to 8 S) DNA polymerase in murine cells can be converted to a low molecular weight DNA polymerase (3.3 S) in the presence of 0.125 M (NH,)tSO+
All other enzymes were purified up to the phosphocelulose step as previously described (l), and the phosphocelulose fractions were further purified on a hydroxyapatite column previously equilibrated with 0.02 M KI’Od (PH 7.5)) 20% glycerol, 0.2% Nonidet
Our experiments show no inhibition of DNA polymerase I by antiserum prepared against DNA polymerase II
Summary
HeLa cell DNA-dependent DNA polymerase I, a low molecular weight enzyme of 40,000 to 50,000, has been compared to DNA-dependent DNA polymerase II, a high molecular weight enzyme. A DNA polymerase II, obtained from cultured Chinese hamster cells, is partially inhibited by the HeLa DNA polymerase II antiserum. The other, DNA polymerase II, has a molecular wight in the range of 100,000 to 200,000 and is generally found in the cytoplasm, it has been reported in the nucleus of cultured human cells such as KB and HeLa [1, 3]. Animal cells contain two other I)NA polymerases, a R-DNA polymerase’ which is distributed in the nucleus and cytoplasm [5] and a mitochontlrial DNA polymerax [6]. Hecht [8] has reported that a high molecular weight (6 to 8 S) DNA polymerase in murine cells can be converted to a low molecular weight DNA polymerase (3.3 S) in the presence of 0.125 M (NH,)tSO+.
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