Chick embryo DNA polymerase beta. Purified enzyme consists of a single Mr = 40,000 polypeptide.
DNA polymerase (EC 2.7.7.7) 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.
D000818:Animals; D002642:Chick Embryo; D002846:Chromatography, Affinity; D004256:DNA Polymerase I / Q000302:isolation & purification* / Q000378:metabolism; D004277:DNA, Single-Stranded; D004259:DNA-Directed DNA Polymerase / Q000302:isolation & purification*; D007700:Kinetics; D008970:Molecular Weight; D010446:Peptide Fragments / Q000032:analysis; D014357:Trypsin
D004277:DNA, Single-Stranded; D010446:Peptide Fragments; D004256:DNA Polymerase I; D004259:DNA-Directed DNA Polymerase; D014357:Trypsin