The author attempted and succeeded in separating and purifying the cysteine protease inhibitors from new gingers. The root and stem of new gingers were extracted with neutral buffer which subsequently underwent heat treatment at 80° C. for 10 minutes. After centrifugal separation, the supernatant was separated with acetone. The fractions that precipitated at an acetone concentration of 55-77% were injected into a chromatographic column of DEAE-cellulose and Sephadex G-75 gel for purification. The results demonstrated that there were two cysteine protease inhibitors with a molecular weight of 11,000-11,800 and 15,500-16,000, respectively, which strongly inhibit papain. The two cysteine protease inhibitors do not have high heat stability.
