Nucleic Acids Research, 1988, Vol. 16, No. 14 6447-6464
© 1988
Articles |
Purification and enzymological characterization of DNA-dependent ATPase IV from the Novikoff hepatoma
Department of Biological Sciences, University of Cincinnati Cincinnati, OH 45221, USA
*To whom correspondence should be addressed
Received March 1, 1988.
DNA-dependent ATPase IV has been purified to near homogeneity from the Novikoff rat hepatoma. The enzyme is devoid of DNA polymerase, RNA polymerase, exonuclease, endonuclease, phosphomonoesterase. 3'- or 5'-phosphodiesterase, polynucleotide kinase, protein kinase, topoisomerase, helicase or DNA reannealing activities at a detection level of 10–5 to 10–7 relative to the ATPase activity. The enzyme is a monomer of Mr 110,000, has a sedimentation coefficient of 5.9 S, a Stokes radius of 40 Å and a frictional coefficient of 1.32. In the presence of Mg2+ ion and a polynucleotide effector, ATPase IV hydrolyzes either ATP or dATP to the nucleoside diphosphate plus Pi. Other ribo- or deoxyribonucleoside triphosphates are not substrates. ATPase IV utilizes double-stranded DNA and single-stranded DNA as effector; however, it does not utilize poly(dT). The Km for dsDNA or ssDNA is 2.2 µM (nucleotide). A variety of ATP analogues were found to be competitive inhibitors of ATPase IV.
+Present address: Department of Biochemistry, University of North Carolina School of Medicine, Chapel Hill, NC 27514, USA