title: A study on the unprimed poly (dA-dT) synthesis catalyzed by preparations of E. coli DNA polymerase I.
abstract: Evidence was obtained indicating that the initiation of poly (dA-dT) de novo synthesis is provided by deoxynucleoside diphosphate: oligonucleotide deoxynucleotidyl transferase (dNDP-transferase present in preparations of E. coli DNA polymerase I and capable of catalyzing the unprimed polymerization of dNDP. dNDP-transferase synthesyzes short oligonucleotides which form template-primer complexes repeatedly replicated by DNA polymerase I. This conclusion was based on the following observations: the abolition of the lag period of poly (dA-dT) synthesis by preincubation of DNA-polymerase I preparations with dADP and dTDP; the presence of oligo (dA-dT) among the preincubation products; the suppressive effect of dithiothreitol and N-ethylmaleimide (inhibitors of dNDP-transferase) on the de novo, but not on the primed synthesis of poly (dA-dT), catalyzed by preparations of DNA-polymerase I.
mesh_terms: D004256:DNA Polymerase I / Q000378:metabolism*; D004259:DNA-Directed DNA Polymerase / Q000378:metabolism*; D004229:Dithiothreitol / Q000494:pharmacology; D004926:Escherichia coli / Q000201:enzymology*; D005033:Ethylmaleimide / Q000494:pharmacology; D007700:Kinetics; D011067:Poly dA-dT / Q000096:biosynthesis*; D011089:Polydeoxyribonucleotides / Q000096:biosynthesis*
chemical_list: D011089:Polydeoxyribonucleotides; D011067:Poly dA-dT; D004256:DNA Polymerase I; D004259:DNA-Directed DNA Polymerase; D005033:Ethylmaleimide; D004229:Dithiothreitol