Specific for apurine-apyrimidine DNA endodeoxyribonuclease from the rat brain

Endodeoxyribonuclease was detected in rat neocortex chromatin. The partly purified enzyme was found to influence the superhelical apurine-apyrimidine DNA 50 times as effectively as compared to the native substrate. The enzyme hydrolyzes the phosphodiester bond with the formation of 3'-OH- and 5'-phosphate terminal groups. The enzyme-hydrolyzed DNA is an effective primer for DNA-polymerase I from E. coli. It was assumed that DNAase from rat brain chromatin is an apurine-apyrimidine endonuclease II.