Identification of a novel 97 kDa endonuclease capable of internucleosomal DNA cleavage

A novel 97 kDa Ca+2/Mg+2-dependent endonuclease was found to mediate apoptosis in cultured 5123tc rat hepatoma cells. The characterization of the enzyme revealed that its mechanism of action is by internucleosomal DNA cleavage which may be responsible for the secondary stages of chromatin degradation in apoptosis. It was also found to be active over a wide range of pH and inactivated by reducing agents. The identity of the new enzyme was confirmed different from known endonucleases such as DNases I and II based on its binding to rabbit polyclonal anti-p97 antibodies.