3.4.22.B50 responsible for the cleavages located at the N-terminus of the replicase polyprotein - - 3.4.22.B50 responsible for the cleavages located at the N-terminus of the replicase polyprotein catalytic cycle and proposed chemical mechanism of the SARS-coronavirus papain-like protease catalyzed reaction, of the catalytic triad residues Cys112 acts as nucleophile, His273 functions as a general acid-base, and Asp287 is paired with histidine helping to align it and promote deprotonation of Cys112, structure-function relationship, overview 731149