Fig. (5) Optimal pH, pH stability, optimal temperature and heat-stability of purified cysteine protease from Actinidia arguta.(A): The purified enzyme (0.5 μg) was incubated in 50 mM citrate buffer and sodium phosphate buffer at various pHs (3.0 ~ 8.0) for 10 min at 37 °C. The activity for Z-Leu-Arg-MCA was determined, and the activity obtained at pH 7.0 was useded as the standard (100%). Each value is the mean ± SE from triplicate experiments. (○): sodium phosphate buffer; (□): sodium citrate buffer. (B): The purified enzyme (0.5 μg) was stored in 50 mM GTA buffer at various pHs (3.5 ~ 10.0) for 24 hr at 4°C, and then the activity for Z-Leu-Arg-MCA was determined. The activity obtained at pH 7.0 was used as the standard (100%). Each value is the mean ± SE from triplicate experiments. (C): The purified enzyme (0.5 μg) was incubated in 50 mM sodium phosphate buffer, pH 7.0, at various temperatures (22 ~ 60°C) for 10 min. The activity for Z-Leu-Arg-MCA was determined, and the activity obtained at 37 °C was used as the standard (100%). Each value is the mean ± SE from triplicate experiments. (D): The purified enzyme (0.5 μg) was pre-incubated in 50 mM sodium phosphate buffer, pH 7.0, at various temperatures (22 ~ 60°C) for 10 min and then incubated for an additional 10 min after an addition of the substrate. The activity obtained at 22°C was used as the standard (100%). Each value is the mean ± SE from triplicate experiments.