Improving the Catalytic Performance of Pectate Lyase Through Pectate Lyase/Cu(PO) Hybrid Nanoflowers as an Immobilized Enzyme.

Pectate lyases (Pels) can be used in the textile industrial process for cotton scouring and ramie degumming, and its hydrolyzed products oligo galacturonic acid, are high-value added agricultural and health products. In our previous studies, an alkaline pectate lyase PEL168 mutant, PEL3, was obtained with improved specific activity and thermostability. Here, a facile and rapid method for preparing an immobilized PEL3-inorganic hybrid nanoflower was developed, as it could improve its biocatalytic performance. With 0.02 mg/mL (112.2 U/mL) PEL3 in PBS buffer, five different divalent ions, including Mn, Ca, Co, Zn, and Cu, were used as inorganic component. The results showed that PEL3/Cu(PO) hybrid nanoflowers presented the highest relative activity with 2.5-fold increase, compared to the free PEL3. X-ray diffraction analysis confirmed that the composition of PEL3/Cu(PO) hybrid nanoflowers were pectate lyase PEL3 and Cu(PO)⋅5HO. The optimum temperature and pH of PEL3/Cu(PO) hybrid nanoflowers were ascertained to be 55°C and pH 9.0, respectively, exhibiting subtle difference from the free PEL3. However, the PEL3/Cu(PO) hybrid nanoflowers maintained 33% residual activity after 24 h incubation at 55°C, while the free PEL3 completely lost its activity after 18 h incubation at 55°C. Furthermore, over 50% residual activity of the PEL3/Cu(PO) hybrid nanoflowers was remained, even after four times of repetitive utilization, demonstrating its promising stability for practical application.