Characterization of the pH 4.0 endonuclease from adenovirus-type-2-infected KB cells

The properties of the pH 4.0 endonuclease from adenovirus-type-2-infected KB cells were determined. The enzyme has a molecular weight of approximately 40000. Its pH optimum is at pH 4.0, it is not inhibited by ethylenediaminetetraacetate (EDTA), and it is active at temperatures up to 60 degree C. The enzyme cleaves adenovirus DNA in a stepwise manner. The limit digestion product has a molecular weight of 120000-200000. There is evidence that the cleavage reaction proceeds via an initial single-strand nick. Under the conditions tested the endonuclease did not seem to reveal a high degree of specificity as to the recognition of cleavage sites, or else the sites recognized occurred very frequently.