Lysosomal acid deoxyribonuclease from vervet monkey livers--I. Purification and physico-chemical characterization

Acid DNase from monkey liver lysosomes was purified to homogeneity by salt extraction of lysosomal membranes at pH 3.8; (NH4)2SO4 fractionation; low salt precipitation; SP-C50 and G-150 Sephadex chromatography; and polyacrylamide gel electrophoresis. The pH for optimum activity was dual in character with a labile optimum at pH 3.8 and a less active but stable one at pH 4.2. The estimated molecular weight was 40K and the pI was 4.4. Inorganic ions such as Ca2+, Mg2+, Mn2+ and SO2-4 were more than 80% inhibitory at 10-mM levels. Fe3+ ions were 80% inhibitory at 0.1-mM levels. NaCl at 100 mM is essential for activity but becomes 100% inhibitory above 200 mM.