The chromatographic and enzymic properties, the sedimentation coefficients, and the mechanism of action on native deoxyribonucleic acid (DNA) shown by acid deoxyribonuclease (DNase) preparations obtained from different animal sources were compared. The results obtained strongly indicate that the enzymatic activity is associated with protein molecules endowed with very similar physical, chemical, and enzymic properties. The enzyme levels in the tissues may vary by as much as three orders of magnitude. The highest acid DNase levels are found in lymphatic and tumoral tissues, the lowest ones in cells like sperms and erythrocytes that do not reproduce themselves.
