Purification and characterization of DNase VII, a 3' leads to 5'-directed exonuclease from human placenta

An exonuclease, DNase VII, has been purified 6000-fold from human placenta. The enzyme has an apparent molecular weight of 43,000, requires Mg2+ for activity, and has a pH optimum of 7.8. The enzyme hydrolyzes single-stranded and nicked duplex DNA at the same rate proceeding in a 3' leads to 5' direction liberating 5'-mononucleotides. It does not measurably hydrolyze polyribonucleotides.