[Separation of the enzyme catalyzing polymerization of deoxyribonucleoside diphosphates from preparations of E. coli DNA-polymerase I].
The enzyme which catalyses template independent synthesis of polydeoxynucleotides from deoxynucleoside diphosphates was separated from E. coli DNA polymerase I by DEAE-cellulose chromatography followed by ultrafiltration through the M-50 Amicon filter. The ultrafiltration data indicate that the molecular weight of the enzyme is not higher than 50,000. The enzyme is not able to use deoxynucleoside triphosphates, ribonucleoside di- or triphosphates as substrates for the polymerization. The reaction of template independent polymerization proceeds with a lag period varying from 2 to 20 hours (for different preparations of enzyme) and is activated by Mg2+ (the optimal concentration 1-2 . 10(-3) M). The pH optimum of the reaction is at 8.5. The optimal concentration of deoxyribonucleoside diphosphates is 10(-3) M, and its increase strongly inhibits polymerization. The enzyme was supposed to be called deoxynucleoside diphosphate: olygonucleotide deoxynucleotidyltransferase (catalyzing polymerization without template). The presence of the enzyme in the preparations of E. coli DNA-polymerase I can explain the ability of the latter to catalyze the untemplated synthesis of poly dG : poly dC.
D004256:DNA Polymerase I / Q000378:metabolism*; D004259:DNA-Directed DNA Polymerase / Q000378:metabolism*; D003854:Deoxyribonucleotides; D004789:Enzyme Activation; D004926:Escherichia coli / Q000201:enzymology*; D007700:Kinetics; D008274:Magnesium / Q000494:pharmacology; D008970:Molecular Weight
D003854:Deoxyribonucleotides; D004256:DNA Polymerase I; D004259:DNA-Directed DNA Polymerase; D008274:Magnesium
Vydelenie fermenta kataliziruiushchego polimerizachiiu dezoksinykleoziddifatov, iz preparatov DNK-polimerazy I E. coli.