title: Purification and properties of deoxyribonucleic acid polymerase from Bacillus stearothermophilus.
abstract: Deoxyribonucleic acid polymerase I was purified from Bacillus stearothermophilus to 50 to 70% homogeneity. Its molecular weight was 76,000. The enzyme was insensitive to sulfhydryl blocking agents and showed maximal activity at 60 degrees C, pH 8 to 9, 0.25 M KCl, and 0.02 M MgSO4. The rate of heat inactivation of the deoxyribonucleic acid polymerase followed first-order kinetics with a half-life of 90 min at 60 degrees C; the addition of 0.05% bovine serum albumin protected the enzyme, which could be heated for 180 min without loss of activity. The ratios of polymerase to nuclease activities were about 20 for 5'-3' exonuclease and more than 500 for 3'-5' exonuclease. The Km for deoxyribonucleoside-5'-triphosphates was 7 microM.
mesh_terms: D002412:Cations / Q000494:pharmacology; D004256:DNA Polymerase I / Q000302:isolation & purification* / Q000378:metabolism; D004259:DNA-Directed DNA Polymerase / Q000302:isolation & purification*; D001411:Geobacillus stearothermophilus / Q000201:enzymology*; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008970:Molecular Weight
chemical_list: D002412:Cations; D004256:DNA Polymerase I; D004259:DNA-Directed DNA Polymerase