HRV 3C Protease encoded by human rhinovirus 14 is a highly purified recombinant cysteine protease with a His-tag. It recognizes the sequence Leu-Glu-Val-Leu-Phe-Gln↓Gly-Pro (LEVLFQ↓GP), cleaving between the Gln (Q) and Gly (G) residues. HRV 3C protease folds into two anti-parallel six-stranded β-barrels and the site cleft is located at the junction of the two β-barrels domains. The enzyme requires neither metal nor cofactors for activity. It has been demonstrated that the enzyme exhibits highest activity around neutral pH at temperature ranging from 22 to 37℃, even retaining robust activity at 4℃. Thus, cleavage can be performed at low temperature to enhance the stability of the target protein. The catalytic activity is insensitive to organic solvents (up to 10%); however, it can be strongly stimulated by high concentration of anions such as sulfate.
