Transformation of rare ginsenoside Compound K from ginsenoside Rb1 catalyzed by snailase immobilization onto microspheres / 中草药

ABSTRACT

Objective: To prepare snailase immobilization onto microspheres and to optimize the process conditions for the transformation of rare ginsenoside Compound K (CK) from ginsenoside Rb1 (Rb1) catalyzed by snailase immobilization onto microspheres. Methods: Considering the recovery rate of enzyme activity as the target, crosslink-embedding method was used for preparing the snailase immobilization onto microspheres and optimizing the preparation technology by orthogonal test. Furthermore, the enzyme characterization of temperature, enzymatic properties of pH value, thermal stability, pH stability, and storage stability was studied, and the effectiveness of temperature, concentration reaction time, and transformational times on the bioconversion rate was studied to optimize the preparation conditions. Results: The best process was achieved at 2% sodium alginate, 2% CaCl2, SiO2 and snail enzyme mass ratio of 11, with the above conditions, the enzyme activity recovery rate was 81.94%, immobilization snailase and free snailase exhibit different properties about thermal stability and pH stability, the optimum temperature was 60℃, and the optimum pH was 5.0. Under these conditions, the snailase immobilization onto microspheres remained 55.17% enzyme activity when storaged at 15℃ for 30 d. The best process was achieved at 55℃, the substrate concentration was 1.0 mg/mL, the conversion time was 36 h, the effective continuous transformational times were five rounds and the average transformational ratio for rare ginsenoside CK was up to 36.79%. Conclusion: The results concluded from the experiments indicate that the immobilization procedure could promote the resistance of enzyme against temperature, pH shift, and some other tough reaction conditions, meanwhile prolong the enzymatic lifetime for storage. The bioconversion rate is impoved and it is feasible to prepare rare ginsenoside CK by enzymolysis with snailase immobilization onto microspheres. Besides, the condition is moderate and it is suitable for industrialization.