Characterization of the chymotryptic core of the adenovirus DNA‐binding protein

A fragment of the DNA-binding protein of adenovirus type 5 has been obtained by controlled chymotryptic digestion of the entire molecule. Partial sequence determination indicates that the fragment consists of amino acids 174-525. The fragment is biologically active as measured by its ability to substitute for the entire molecule in a reconstituted DNA replication system. Crystals have been obtained that show diffraction to 2 A.