Chick embryo DNA polymerase beta. Purified enzyme consists of a single Mr = 40,000 polypeptide

J Biol Chem. 1980 Oct 25;255(20):9942-8.


DNA polymerase (EC beta was purified to near homogeneity from chick embryos. The final preparation has a specific enzyme activity of 1,100,000 units (nanomoles of dTMP incorporation/h) per mg of protein with (rA)n X (dT)12-18 as a template-primer. The molecular weight of DNA polymerase beta is about 40,000 as judged by gel filtration on Sephadex G-150 column. The results of sodium dodecyl sulfate-polyacrylamide gel electrophoresis indicated that the polypeptide of Mr = 40,000 accounted for 95% of total protein in the final preparation. The fingerprint analysis of tryptic peptides of polypeptide shows that 14 out of 24 125I-peptides from the Mr = 40,000 polypeptide are the same as those of the Mr = 40,000 polypeptide of DNA polymerase beta purified from rat ascites hepatoma cells. A Mr = 27,000 polypeptide, which was present in the less pure preparation, did not show any structure similar to Mr = 40,000 polypeptides from rat and chick cells. Thus, it is concluded that chick embryo DNA polymerase beta consists of a single polypeptide of Mr = 40,000. The minimal number of DNA polymerase beta molecules per chick embryo cell was estimated as about 5,000.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Chick Embryo
  • Chromatography, Affinity
  • DNA Polymerase I / isolation & purification*
  • DNA Polymerase I / metabolism
  • DNA, Single-Stranded
  • DNA-Directed DNA Polymerase / isolation & purification*
  • Kinetics
  • Molecular Weight
  • Peptide Fragments / analysis
  • Trypsin


  • DNA, Single-Stranded
  • Peptide Fragments
  • DNA Polymerase I
  • DNA-Directed DNA Polymerase
  • Trypsin