DNA polymerases from Chlamydomonas reinhardii. Purification and properties.
Three DNA polymerase activities, A, B and C, were identified in extracts of exponentially growing synchronous cultures of Chlamydomonas reinhardii, and DNA polymerases A and B were characterized in detail. Both enzymes have the same binding affinity for DEAE-cellulose at pH 7.8, but can be distinguished from each other by their behaviour on phosphocellulose and DNA-agarose. 'Activated' calf thymus DNA was used as template, and the pH, K+ and bivalent-cation optima were measured. DNA polymerase A sediments at 5.3 S in glycerol gradients, with an apparent mol.wt. of 90000-100000. Polymerase B sediments between 8S and 10S in 100mM-KCl, the predominant species having an apparent mol.wt. of 200000. In 200mM-KCl, polymerase B dissociates to a single species, which sediments at 5.8S. A 3S species was found in aged preparations of both enzymes. The activity of polymerase B from cells harvested during nuclear DNA synthesis is twice that found in Chlamydomonas at other times during the cell cycle.
D002412:Cations / Q000494:pharmacology; D002453:Cell Cycle; D002499:Centrifugation, Density Gradient; D002696:Chlamydomonas / Q000166:cytology*; D002847:Chromatography, Agarose; D002848:Chromatography, DEAE-Cellulose; D004259:DNA-Directed DNA Polymerase / Q000302:isolation & purification* / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D008970:Molecular Weight
D002412:Cations; D004259:DNA-Directed DNA Polymerase