A new mammalian DNA polymerase with 3' to 5' exonuclease activity: DNA polymerase delta

Biochemistry. 1976 Jun 29;15(13):2817-23. doi: 10.1021/bi00658a018.


A new species of DNA polymerase has been purified more than 10 000-fold from the cytoplasm of erythroid hyperplastic bone marrow. This DNA polymerase, in contrast to previously described eukaryotic DNA polymerases, is associated with a very active 3' to 5' exonuclease activity. Similar to the 3' to 5' exonuclease activity associated with prokaryotic DNA polymerases, this enzyme catalyzes the removal of 3'-terminal nucleotides from DNA, as well as a template-dependent conversion of deoxyribonucleoside triphosphates to monophosphates. The exonuclease activity is not separable from the DNA polymerase activity by chromatography on DEAE-Sephadex or hydroxylapatite, and upon sucrose density gradient centrifugation the two activities cosediment at 7 S or at 11 S depending on the ionic strength. Both exonuclease and polymerase activities have identical rates of heat inactivation and both are equally sensitive to hemin and Rifamycin AF/013, inhibitors of DNA synthesis that act by binding to DNA polymerase and causing its dissociation from its template/primer. These results are consistent with the coexistence of two enzyme activities in a single protein.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Bone Marrow / enzymology*
  • DNA Nucleotidyltransferases / isolation & purification
  • DNA Nucleotidyltransferases / metabolism*
  • Drug Stability
  • Erythroblasts / enzymology*
  • Erythrocytes / enzymology*
  • Exonucleases / isolation & purification
  • Exonucleases / metabolism*
  • Hemin / pharmacology
  • Humans
  • Kinetics
  • Temperature


  • Hemin
  • DNA Nucleotidyltransferases
  • Exonucleases