Purification and some properties of two deoxyribonucleases from Aspergillus niger.

Two deoxyribonucleases (DNase A and DNase N) were isolated from Aspergillus niger and partially purified. The purification procedure consisted of five steps, including am-monium sulfate fractionation, column chromatographies on DEAE-cellulose and DEAE-sephadex, gel filtration on Sephadex G-100 column, and affinity chromatography on 5'-GMP-Sepharose 4B column. The purified DNase A and DNase N were the most active at pH 4.0 and pH 6.5, and their molecular weights were found to be about 39, 000 and 12, 000, respectively. The DNase A was markedly inhibited by Ag+ and Cu2+, and activated by Zn2+. DNase N hydrolyzed dG-pdG and dG-pdA linkages, and DNase A preferentially hydrolyzed dG-pdG and dG-pdA linkages of calf thymus DNA.