HU Ai-jun^1,, CAO Yuan-yuan¹, QU Ying¹, SONG Fei-ying¹, ZHENG Jie¹

This study investigated the effect of ultrasonic irradiation on the hydrolytic reaction of AS1.398 neutral protease. Our results showed that the light absorbance increased dramatically under the combination of the three conditions, ultrasonic radiation, increased amount of enzyme and longer incubation period. This increase was also observed when enzyme amount and reaction duration kept constant, with ultrasonic radiation as the only variable. In addition, the changes in light absorbance followed a parabolic curve under conditions of increasing pH and temperature, reaching the peak at an optimal pH and temperature and then decreasing sharply. We concluded that ultrasonic irradiation could accelerate the velocity of the enzymatic reaction, however, did not alter the optimal pH and temperature of the reaction. With no ultrasonic irradiation, the enzyme kinetic equation was v=59.88[S]/(21.49+[S]). Ultrasonic irradiation increased the velocity constant, but decreased the Michaelis constant (Km), the equation became v=63.69[S]/(18.60+[S]) with ultrasound. In summary, ultrasound-assisted enzymatic activity of neutral protease led to higher hydrolysis.

ultrasonic irradiation, AS1.398 neutral protease, enzymatic hydrolysis