researchers have used a method called ‘crystallization’ through which they have been able to isolate and further investigate role of ns2-3 protease. his143, cys184 and glu 163 are the three crucial resides responsible for proteolytic activity. these three residues together form an active site. although ns2 protease has been proposed to have a unique fold, it is shown that superimposing three critical residues from other cysteine proteases revealed a major characteristic which would allow for more specific inhibitor studies. researchers in this case used cysteine proteases such as papain and poliovirus 3c protease. ns2 dimer contains two active sites and requires dimerization for proteolytic activity.