title: Mechanism of DNA polymerase I: exonuclease/polymerase activity switch and DNA sequence dependence of pyrophosphorolysis and misincorporation reactions.
abstract: Mechanistic features of several processes involved in the idling-turnover reaction catalyzed by the large (Klenow) fragment of Escherichia coli DNA polymerase I have been established. The exonuclease----polymerase activity switch involved in the excision/incorporation mode of idling-turnover occurs without an intervening dissociation of the enzyme from its DNA substrate. Comparative studies on the pyrophosphorolysis kinetics of related DNA substrates indicate a significant dependence of the reaction rate upon the DNA sequence within the duplex region upstream of the primer-template junction. Finally, a gel electrophoretic analysis of the products of the idling-turnover reaction has provided direct evidence for an alternative DNA sequence-dependent misincorporation/excision pathway.
mesh_terms: D001483:Base Sequence; D004256:DNA Polymerase I / Q000378:metabolism*; D011756:Diphosphates / Q000378:metabolism; D004926:Escherichia coli / Q000201:enzymology*; D005090:Exodeoxyribonucleases / Q000378:metabolism*; D007700:Kinetics; D013379:Substrate Specificity
chemical_list: D011756:Diphosphates; D004256:DNA Polymerase I; D005090:Exodeoxyribonucleases