Immobilization of phospholipase D on macroporous SiO2/cationic polymer nano-composited support for the highly efficient synthesis of phosphatidylserine

• Novel nano-composites were prepared for immobilization of phospholipase D (PLD). • The storage stability and reusability of PLD were greatly improved through ion exchange. • Application of amphiphilic supports in biphasic enzymatic reactions. Novel nano-composites were prepared by coating epoxy resin-based cationic polymer in nano-thickness via in-situ curing on the nano-wall of macroporous SiO 2 with pore size of 0.5∼1 μm. By changing the thickness of polymer coating the specific surface area and porosity varied in range of 115∼74 m 2 /g and 90.4∼83.9 %, respectively. Through ion exchange phospholipase D (PLD, from Streptomyces sp ) was efficiently immobilized on the nano-composites as support and the immobilized PLD was applied for the highly efficient synthesis of phosphatidylserine (PS). The loading amount of PLD on the nano-composited support reached to a maximum of 90.2 mg/g support , 4 times as high as that on the pure macroporous silica. The specific activity of the immobilized PLD reached as high as 16,230 U/g protein , while that of free PLD was 18,780 U/g protein . Under a wide range of temperature and pH the stability and activity of the immobilized PLD were greatly improved as compared with the free ones. Under optimized conditions at 45 °C and pH 7.0, the PS yield reached as high as 96.2 % within 40 min. After 28 days storage the immobilized PLD retained 82.2 % of original activity, and after 12 cycling reuses it retained 79.3 % of PS yield, which indicated that the immobilized PLD exhibited good stability.