Dinucleotides as Products of an Exonucleolytic Activity Associated with the Micrococcus luteus DNA Polymerase

The partially purified DNA polymerase from Micrococcus luteus contains a low level of exonucleolytic activity. The enzyme preparation (1200-fold purified) contains approximately 100 times more polymerase than exonuclease activity. Both single- and double-stranded DNA are degraded at the same rate. The predominant products are dinucleoside diphosphates (d-pXpY); mononucleotides and a trace of trinucleotides are also produced. Each of these products is formed at a constant rate throughout the course of the reaction. The nuclease degrades a DNA chain from the 5'-end. The enzyme preparation contains no detectable endonuclease activity.