Mechanistic Studies on DNA Polymerase I
The multifunctional DNA polymerase I (Pol I) of Escherichia coli has served as the most widely studied model for describing, at the molecular level, certain enzymatic processes involved in the replication of DNA (1). In addition to its polymerase activity, the enzyme also catalyzes DNA degradation by distinct 5′ → 3′and 3′ → 5′ exonuclease activities, as well as by net pyrophosphorolysis. Extensive kinetic (2, 3) and stereochemical (4, 5) studies of the various activities have elucidated the important underlying features of the phosphodiester bond-forming and bond-breaking reactions. In addition, the availability of a 3-Å resolution x-ray structure of the large proteolytic (Klenow) fragment of Pol I (6) has generated considerable interest in the area of structure—function assignment (7).
KeywordsTriphosphate dNTP Monophosphate Phospho Diester
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