Metal content of DNA polymerase I purified from overproducing and wild type Escherichia coli.

DNA polymerase I purified from both E. coli strain B, and from an overproducing E. coli stain lysogenized with a lambda pol A phage were analyzed for metal content. After gel filtration to remove loosely bound metals, DNA polymerase I from both strains contained less than or equal to 0.2 gm atoms Zn2+/mole enzyme and 0.09 to 0.7 Mg2+/mole enzyme. Substoichiometric amounts of Fe, Co, Ni (less than or equal to 0.2 gm atoms), and Mn (less than or equal to 0.1 gm atoms) were detected. Since the metal content does not correlate with enzymatic activity, we conclude that DNA polymerase I is not a metalloenzyme.