Human adenovirus proteinase is a cysteine proteinase required for the synthesis of infectious virus. Cofactors discovered include viral DNA, or a short oligopeptide which the enzyme itself cleaves out. The enzyme cleaves specific Gly-Ala peptides in a number of viral precursor proteins, and also cleaves host cell cytoskeleton keratins. The structure and mechanism of this enzyme suggest convergent evolution to give a catalytic mechanism similar to papain.
Defined by 4 residues: HIS:A-54GLU:A-71GLN:A-115CYS:A-122