Inhibition of papain activity by recombinant sesame phytocystatins. Papain was mixed with various amounts of recombinant SiCYS, SiCYS-N and His-tagged SiCYS-C, respectively. The residual hydrolytic activity was determined and present as percentage of total activity of papain. The final concentration of papain was 1.24 μM in a 350 μl reaction. The added recombinants were depicted as the concentration of cystatin, μM as well. The assay was performed three independent times and presented as mean ± S.E.