All adenoviruses (Ads) sequenced so far encode a single endopeptidase of the cysteine class, named adenain. The Ad2 adenain is a 204-residue, nearly inactive monomer, which is activated during virus maturation by an 11-residue cleavage fragment of capsid protein pVI. This chapter describes the synthesis, purification, activation, and assay of recombinant human Ad type adenain.
