A Deoxyribonuclease Which Requires Nucleoside Triphosphate from Micrococcus lysodeikticus

Extracts of Micrococcus lysodeikticus contain a deoxyribonuclease, which has a specific requirement for the presence of nucleoside triphosphate. The role of nucleotide during the reaction has been investigated in detail in this study. Of nucleoside triphosphates tested, ATP and dATP are most effective, and dCTP is inactive, while other nucleoside triphosphates are relatively feeble. Nucleoside di- or monophosphates are inactive. At the low concentration of ATP the initial rate and final extent of DNA hydrolysis are proportional to the amount of ATP. The Km for ATP is 5.0 x 10-5 m, and the Km for dATP is the same as that for ATP. ATP is converted to ADP and inorganic orthophosphate during the process of DNA hydrolysis. The ratio of the amount of ATP cleaved to that of hydrolyzed phosphodiester bonds of DNA is approximately 3:1.