Partial Purification and Properties of a Nuclease from Chicken Pancreas

A nuclease has been isolated from an acid homogenate of chicken pancreas and purified over 300-fold. The purified preparation was free of phosphomonoesterase and phosphodiesterase activity, but rapidly hydrolyzed ribonucleic acid and deoxyribonucleic acid. The enzyme which by several criteria was a single protein required Mg ++ or Mn ++ for activity; addition of excess ethylenediaminetetraacetate completely inhibited all of the nuclease action. The pH optimum for RNA was around 9.5 and for DNA around 8.8. The enzyme was found to be completely inactivated by heating for 10 min at 70°, but on heating at 80° from one-quarter to one-third of the activity was restored. There appeared to be no free sulfhydryl groups essential for enzyme activity. Iodoacetate at the proper concentration completely inhibited ribonuclease activity, but had little or no effect on deoxyribonuclease activity.