Activity assay of recombinant AaJHA15. Purified His-JHA15 fusion protein was tested for chymotrypsin activity using synthetic substrate AAPF (N-succinyl-Ala-Ala-Pro-Phe-nitroanilide). The experiment was performed as described in Materials and Methods. JHA15 was activated by trypsin treatment, and the enzyme activity is shown as the increase in the absorption at 410 nm. A blank control was used to correct the spontaneous hydrolysis of the substrate. Chymostatin is a strong inhibitor of many proteinases, including chymotrypsin, chymotrypsin-like serine proteinases, chymases, and lysosomal cysteine proteinases. Values are means ± SEM.