Purification and partial characterization of a 33 000 molecular weight endonuclease associated with human adenovirus type 5

An endonuclease activity has been purified from human adenovirus type 5 (HAd5) virions and HAd5-infected cell extracts. The endonuclease activity is associated with a monomeric protein of molecular weight approximately 33 000. The endonuclease activity is more active at pH 4.5 than pH 7.2. Incubation of the enzyme at room temperature for periods of longer than 96 h results in a substantial increase in activity. The endonuclease activity is sensitive to EDTA at concentrations 10 mM or greater but is insensitive to 500 mM NaCl. Immunological analysis with endonuclease specific antiserum indicates that the endonuclease may be a host cell derived, viral modified, and incorporated protein.