Purification and properties of human pancreatic deoxyribonuclease I.

Human pancreatic DNase I was purified extensively from duodenal juice of healthy subjects by a procedure including ammonium sulfate fractionation, ethanol fractionation, phosphocellulose fractionation, isoelectric focusing, and gel filtration. The final preparation was free of DNase II, pancreatic RNase, alkaline phosphatase, and protease. The enzyme had a molecular weight of approximately 30,000, as determined by gel filtration on Sephadex G-100, and showed maximum activity at pH 7.2-7.6. It required divalent cations for activity, and caused single-strand breaks by endonucleolytic attack on double- as well as single-stranded DNA molecules. The enzyme was inhibited by actin and bovine pancreatic DNase I antibody.